Spring 2016 Velociraptor: Sensors

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By: Ashlee Chang (E&C)

Updated: 04/05/16

Table of Contents

Fulfilling the Requirements

Level 2 requirements #9 and #10 are stated as follows:

9. For the Velociraptor to have the ability to travel up a 6.5-degree incline, a gyroscope/accelerometer shall be implemented to preserve the chassis balance and thus meeting the Project Level 1, requirement 6.

10. In order for the robot to detect obstacles at a range of 20 cm in its path, an ultrasonic sensor shall be implemented to the build of the Velociraptor and thus meeting the Project Level 1, requirement 7. 

Thus, the two sensors that will be implemented on the Velociraptor will be an ultrasonic sensor and a gyroscope/accelerometer. Below are the trade-off studies conducted, analyses on the best option, and the team’s final decision.

How the Sensors Work

Ultrasonic Range Finder

Ultrasonic sensors use a process called echolocation, which uses sound as a form of location. A high frequency sound wave is generated; the time it takes for the sound to bounce off an object and back to the sensor determines the distance away from the object it is.

Gyroscope/Accelerometer

A gyroscope/accelerometer is a device to measure acceleration forces. Using this information, one can determine the plane at which the robot is tilted at with respect to Earth. It has crystal structures contained within it that generates vibrational stress to acceleration, inducing a voltage level reading.

Trade-off Studies

Ultrasonic Range Finder

tradeoffultrasonic

Ultrasonic Sensors Comparison

The first option is the component used for last semester’s MicroBiped. The neck and head length of the velociraptor will be approximately 15-20 cm long, which is the minimum distance the ultrasonic sensor must be able to detect. All of the ultrasonic sensors compared have at least a 2 cm minimum range. The velociraptor must be able to respond to an object forward-facing it, most likely 5-10 distance away from the end of its head. All of the maximum ranges for the ultrasonic sensors are well over 400 cm, which makes any of the options fine. Most standard sensors have a dimension of 50 x 15 x 14 mm, weight 10 g, need a 5 V power supply, and generate ultrasonic waves at 40 kHz. The resolutions range from 0.3 to 1 cm, all which are exceptional as the Arduino coding can be set up to respond at any point. The angle at which the echoes can bounce back is documented in the last column of the table. The RB-See-90 has an angle measurement double than the other ultrasonic sensors, but is also 5x the price. As demonstrated below, as the velociraptor approaches the hindering obstacle, the obstacle takes up a wider view within the vision of the ultrasonic sensor. Thus, a measuring angle of 15* is sufficient. These ultrasonic sensors use a PWM interface; a 10 micro-s pulse will initiate the ranging, and a pulse duration is outputted based on if and how far an object is away. The calculation for distance is Distance = [(Duration of high level)*(Sonic 340 m/s)]/2.

pic3

Measuring Angle and Distance

  • List of Products:
[SainSmart HC-SR04]: http://www.sainsmart.com/ultrasonic-ranging-detector-mod-hc-sr04-distance-sensor.html

[Banggood HY-SRF05]: http://www.banggood.com/HY-SRF05-Ultrasonic-Distance-Sensor-Module-Measuring-Sensor-Module-p-91444.html?currency=USD&createTmp=1&utm_source=google&utm_medium=shopping&utm_content=saul&utm_campaign=Electronic-xie-us&gclid=CK7pwoHpissCFYVCaQodpXIBbw

[GearBest HC-SR04]: http://www.gearbest.com/development-boards/pp_58067.html?currency=USD&gclid=CIeQwMrsissCFYM8aQodFM4FOw

[SeeedStudio RB-See-90]: http://www.robotshop.com/en/seeedstudio-ultrasonic-range-finder.html?gclid=CJ7LmePtissCFYSDaQodBvQOsg#productsReviewBoxTitle

[MaxBotix MB1030]: http://www.maxbotix.com/Ultrasonic_Sensors/MB1030.htm

Gyroscope/Accelerometer

gyroacceltradeoff

Gyroscope/Accelerometers Comparison

With accelerometers, there is a trade-off between the measuring range and its sensitivity. A smaller range will provide a more accurate reading, but won’t be able to handle higher velocities, and vice versa. For stationary tilting. Range notation is written as +#g. For tilting, +1.5g is recommended, robots +2g is recommended, for sudden stops +5g is recommended, and for vehicles such as a spaceship +250g is recommended. So the choice in range for the velociraptor should at least +2g. The weight and dimensions of the accelerometers are all similar, and won’t be a factor in the final decision. Ideally, a PWM output type would be ideal to work with in the Arduino because of its simplicity. However, all accelerometers researched seemed to either have an analog or a serial interface; the serial interface uses SPI (serial peripheral interface) and I2C (inter-integrated circuit). The E&C division manager recommended not to use such interface as it is difficult to master dealing with such data. Analog Device’s ADXL335 supports an analog interface, which will provide data that will be easy to work with.

  • List of Products:
[Freescale Semiconductor MMA8451]: https://www.adafruit.com/products/2019?gclid=CISlz8P1issCFQmQaQodjKwLqQ

[Freescale Semiconductor MMA8452Q]: http://www.robotshop.com/en/triple-axis-accelerometer-breakout-board-mma8452q.html?gclid=CNfjjqWEi8sCFQmqaQodNSYPGQ

[Analog Devices ADXL345]: https://www.adafruit.com/products/1231

[Analog Devices ADXL335]: https://www.sparkfun.com/products/9269

[Kootek GY-521]: http://www.amazon.com/Kootek-MPU-6050-MPU6050-sensors-Accelerometer/dp/B008BOPN40

Conclusion

pic5

GearBest HC-SR04 and Analog Device ADXL335

The sensors the velociraptor team would like to go with are GearBest’s HC-SR04 ultrasonic sensor and Analog Device’s ADXL335 accelerometer. The former was chosen based on an economical decision, as all ultrasonic sensors met the requirements in distance detection, resolution, and angle sensitivity. The latter was chosen because it not only has a more than sufficient measurement range of +3g, but also outputs analog data, a much easier interface to work with over SPI and I2C.

Update: Due to unforeseeable circumstances, the velociraptor team had to make some changes regarding the sensor choices. In regards to the ultrasonic sensor HC-SR04, the sensor was no longer functional once the object in front was out of range capability. Most HC-SR04s cheaply manufactured in China overlooked this important flaw. Once a high frequency wave was sent out, the sensor would standby and wait until this wave bounced off the object and returned. With no object in front of the sensor, the HC-SR04 would continue waiting. A clap of the hands or even shaking the sensor would act as a return signal, and the Arduino serial monitor would stop returning the error value -1. This is why the velociraptor team decided on investing in a nicer, better quality rangefinder that met the velociraptor requirements. The E&C division manager had a quality ultrasonic sensor on-hand, which our team purchased. For the gyroscope/accelerometer, there was miscommunication on what sensor was to be used for sensing orientation. Initially the team was told to use an accelerometer, hence the ADXL335 choice. However a couple weeks ago, the team was informed that a gyroscope was to be used, as analog inputs are actually more difficult to handle. Testing the GY-521 gyroscope/accelerometer combination board, a sample code was uploaded provided online, which was hundreds of lines long, using serial output type. Upon uploading to the Arduino, the code took up over an outstanding 50% of flash memory. Because the current walking code and Bluetooth code are approximately 20% each already, the team saw using this serial output type orientation sensor as unfeasible. Therefore, the team is sticking with the ADXL335 choice. Both the MaxSonar ultrasonic sensor and ADXL335 accelerometer codes have been tested and work successfully with some degree of accuracy.

IMG_4506

MaxBotix LV-MaxSonar-Ez3 MB1030 and Kootek GY-521

Works Cited

[1] Ultrasonic transducer: https://en.wikipedia.org/wiki/Ultrasonic_transducer

[2] Accelerometer: https://en.wikipedia.org/wiki/Accelerometer

[3] A beginner’s guide to accelerometers: http://www.dimensionengineering.com/info/accelerometers

[4] Accelerometer, Gyro and IMU Buying Guide: https://www.sparkfun.com/pages/accel_gyro_guide

 

Spring 2016 Velociraptor: Material Trade-Off Study

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By Mingyu Seo (Manufacturing & Design)

Approved by Khoi Vu (Project Manger)

For the Velociraptor Project, we have considered several materials for manufacturing prototypes as well as for our final robot. The chart shows advantages and disadvantages of the material, to help us consider the different materials we’ll use for the velociraptor:

Capture

Through careful consideration, we chose to use 3D material to build our prototype. Using a 3D printer will give use the advantages of faster printing speed, quick solidification, and are easily accessible. 3D materials shown above such as PLA, ABS, and PVA are flexible, strong durability, and have sharp printed corners which are made for ideal small parts. Although the plastic material may have lower temperature resistance compare to Aluminum, building a prototype with a 3D model will let us make adjustments by applying heat to it.  We have considered using PLA (Polylactic Acid) material due to its advantages of sharper printing corners, low material cost, maximum printing speed, and accessibility on campus. All 4 materials were considered as a possible material for our final robot. But Aluminum was chosen to be used as the material to build the final robot due to its economical, strong durability and non-magnetic/electrical conductive traits. Due to aluminum’s disadvantages of the necessity of specific printing machine and non-malleability, our team has considered it should be used after finalization of the dimension of our robot in order to minimize cost as well as time.

Spring 2016 Velociraptor: Course Analysis

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By Khoi Vu (Project Manager)

IMG_0047 (2)

Figure 1: Actual Course

This is the analysis of the course in which the Velociraptor biped robot will need to complete. This course contains multiple surfaces that the robot will need to be able to walk on. Furthermore, the course will also have an obstacle that the robot will lift its leg high enough to walk over. It will also encounter another obstacle that it will have to avoid and navigate itself around it. This obstacle will be the size of a textbook.

Surfaces:

1.The first surface the robot will encounter will be linoleum. The coefficient of friction of linoleum tiles will vary from 0.3 to 0.5 depending on the amount of waxed that is on the tiles. (Refer to works cited 1)

12

Figure 2: Linoleum Tiles

 

2.In the second surface, the robot will encounter is a 3.5 cm rubber bar with the height 0.3 cm. According to the Engineer’s Handbook, the coefficient of friction between rubber and a solid is 1.0. The rubber bar separates the Linoleum tiles and Berber Carpet.(Refer to works cited 2)

IMG_0047

Figure 3: Rubber Bar

 

3.Finally, the robot will also walk on Berber Carpet for the remainder of the course. The carpet has a 0.58 as its coefficient of friction. (Refer to works cited 3)

IMG_0557Figure 4: Berber Carpet

 

course

Figure 5: Measured Course Using SolidWorks

IMG_0594

Equation 1: Calculation of the Incline angle

In Equation 1, the formula calculates the angle of the incline of the course by measuring the adjacent side of the angle and the maximum height of the ramp.

Works Cited

  1. http://www.floorcare-usa.com/pdf/CoefficientFriction.pdf
  2. http://www.engineershandbook.com/Tables/frictioncoefficients.htm
  3. http://www.am20.com/pdf/AthleticFloor8pg.pdf

Spring 2016 Velociraptor: Preliminary Project Plan

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Khoi Vu (Project Manager)

Camilla Jensen ( Systems and Test Engineer)

Table of Contents

Work Breakdown Structure

Figure 1 describes the work distribution for project Velociraptor. There are three branches which consist of Mission, Systems, and Test, Electronics and Control, and Design & Manufacturing. Each branch has its unique work breakdown headed by individual engineers. All three branches will be overseen by the Velociraptor’s Project Manager

 

WBS

Figure 1

Project Schedule

Top Level Schedule

The charts shown below are the preliminary work schedule that Velociraptor’s team members are assigned. Each task has a start and a deadline that must be completed. Tasks are divided based on the Work Breakdown Structure (WBS) in figure 1.

Capture

Figure 2

gantt

Figure 3

Burn Down and Project Percent Completion

The burndown chart provides an insight on the hours of  work that had been contributed and the remaining hours that are needed to complete the project. This chart shows how productive the team has been for the past two months.

Screen Shot 2016-02-23 at 9.11.25 PM

Figure 4

System/Subsystem Level Tasks

 

Camilla Jensen (Systems Engineer)

1.  Learning C++ programming language to write algorithms using the Arduino IDE to

decode instructions to the Velociraptor from the Arxterra Application on an Android

device.

2. Learning how to use the HC-06 Bluetooth wireless device and configure with the

Arxterra Application.

3. Generated system resource reports (Mass, Power and Budget) that will define the size of

battery for Velociraptor.

4. Will work with E&C to optimize walking codes for Velociraptor.

5. Will create verification and validation test plan and perform tests to ensure each device

meets all defined requirements.

 

Ashlee Chang (Electronics & Control Engineer)

1. Research servo options and conduct a trade-off study to select the most fitting servo to handle the total mass of the velociraptor.

2. Research sensor options and conduct a trade-off study to select the most fitting ultrasonic sensor and accelerometer to meet the object detection and adaption to incline requirements.

3. Generate a fritzing diagram with all electrical components to map out all wire connections and testing on a breadboard

4. Prepare a circuit schematic in Eagle CAD that will be passed on to M&D for manufacturing

5. Research power subsystem requirements, selecting an appropriate battery, and meeting the specific voltage and amperage requirements of each component

6. Test the PCB to ensure all electrical components are fully operational.

7. Write the Arduino C++ walking code to control the servos; this includes static walking, dynamic walking, adapting to an incline using the accelerometer sensor, being able to turn in response to an object hindrance

8. Work with S&T on the interfacing between the velociraptor Bluetooth and Arxterra app

 

Mingyu Seo (Manufacturing & Design)

1. Create a complete 3D model of the Velociraptor by using Solidworks for the prototype.

2. Perform stress analysis, Center of Mass, and breaking points to determine the acceptability of

the robot.

3. Build a prototype for Electronics and Systems Engineer to validate MCU subsystem & Control

Firmware as well as for final robot validation.

4. Fabricate the PCB design provided by Electronics Engineer and order an SMT solder paste stencil.

5. Manufacture mechanical parts for velociraptor using the laser cutter.

6. Specify and order off-the-shelf parts for final assembly of the robot.

 

System Resource Reports

Since the goal for this semesters Velociraptor was to reduce the mass from last semesters MicroBiped, the project allocation has been set to 1.00kg and thus reduce the bulkiness and increase stability for the robot.

Mass

Figure 5: Mass Report

In the figure below (figure 6) presents the estimated power consumption of the Velociraptor biped robot. The majority of the power will be consumed by the eight servos that is used to provide torque for movement of legs, tail, and head.

Power

Figure 6: Power Report

Project Cost Estimate

Cost

Figure 7: Estimated Project Cost

Figure 7 is the estimated cost that will be required to manufacture the Velociraptor biped robot. The margins of the Cost Report displays an estimated price for shipping. Many of the parts had free shipping or it was included in the price of the product. The Battery charger’s  shipping costs were 4 times the cost of the charger since it’s shipped from China.

Spring 2016 A-TeChToP Preliminary Project Plan

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By: Cody Dunn (Project Manager)

Omar Rojas (Systems Engineer, Central Sensor Suite)

Robin Yancey (Systems Engineer, Seizure Watch)

Read more

Spring 2016 Millennium Falcon Preliminary Design Document

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BY:

Luis Valdivia (Project Manger)

Anthony Becerril (Systems Engineer)

Juan Mendez (Manufacturing Engineer)

Kevin Nguyen (Electronics Engineer)

Table of contents: 

  • Program Objective 
  • Level 1 Requirements
  • Level 2 Requirements
  • Design Innovation
  • Subsystem Requirements
    • Product Breakdown Structure
    • Electronics System Design
      • System Block Design
      • Interface Definition
    • Manufacturing Design
  • Design and Unique Task Descriptions

 

Program Objective:

The Program Objective of the Millennium Falcon is to produce a safe, low cost, and durable quadcopter using ducted fans. The Millennium Falcon quadcopter will allow user friendly connectivity to an RC controller or any smartphone device using the Arxterra application. The project shall explore multiple innovative design solutions for yaw control leading to stable flight during operation of quadcopter. Stable horizontal flight control will also be addressed, as a design feature. The aircraft will resemble the famous spaceship from the Star Wars movie franchise with a newly designed shell and programmable lights.

Mission Profile:

The Mission Profile for the Millennium Falcon is to complete a flight course outside out CSULB property. The Millennium Falcon quadcopter must maintain stable flight as it circles around a tree in the field across the Whaley Park Community Center. Before attempting flight, the aircraft must be registered with the Federal Aviation Administration to ensure a safe environment for others.  

Level 1 Requirements:

  1. The Millennium Falcon quadcopter team, aims to maintain flight stability.
  2. An enclosure box will protect battery.
  3. A new Printed Circuit Board (PCB) must be re-designed.
  4. New shell for aircraft intends to resemble aesthetic requirements.
  5. Millennium Falcon quadcopter must have longer landing legs to support vehicle.
  6. Quadcopter is expected to implement user input from wireless communication.
  7. The Millennium Falcon quadcopter must display a programmable light show during flight.
  8. Quadcopter will perform designated flight path while meeting safety requirements
  9. Purchases and services for material items must not exceed budget.

 

Level 2 Requirements:

  1. The Millennium Falcon quadcopter team, aims to maintain stability by using a fifth Electric Ducted Fan (EDF) for yaw rotation control. If side fan solution is not implemented, EDF orientation, specifically bracket angle, will be optimized for Millennium Falcon quadcopter stability during flight.
  2. A battery enclosure box must structurally support the weight of the battery and protect it from impact.
  3. New PCB will be required to keep all wiring internal and not exposed. Crystal oscillator, resistors, capacitors will be internally designed contrary to previous semesters design.
  4. New shell casing will meet aesthetics by resembling the Millennium Falcon spaceship from the Star Wars movies. New shell casing also will feature a latching system to secure shell onto Millennium Falcon quadcopter frame.
  5. Removable landing legs must support the entire weight of the vehicle and lift it at least one inch off the ground.
  6. Wireless control of the Millennium Falcon quadcopter will be done by communicating via the Arxterra smartphone application supported on both android and apple as well as via bluetooth remote control.
  7. The Millennium Falcon quadcopter light show must be customizable via Arxterra smartphone application.
  8. The Millennium Falcon quadcopter will perform designated flight path at the CSULB traffic circle while meeting requirements set by the Federal Aviation Administration (FAA) , Unmanned Aircraft Systems (UAS) and College of Engineering (COE).
  9. All purchases and services cannot exceed $400.00 with the guidance of project manager and customer approval.

Design innovation:

Below you can see the creative design process used in the creativity exercise.

Creative solution for vehicle protection: 

Creative Desing

Creative solution for controlling yaw rotation:

Creative Desing2

Subsystem Requirements:

Product Breakdown Structure (PBS):

Below in the product breakdown structure, all components of focus are outlined with details explaining their purpose.

pbs

Electronics System Design:

Wireless Communication

  • An RC control will be created to control the Millennium Falcon quadcopter.
  • A smartphone application will be implemented to control the Millennium Falcon quadcopter. This application will be compatible with android and apple mobile devices.

Light Show

  • Light show must be controlled through Arxterra application.

5th Ducted Fan

  • 5th EDF must have enough thrust to counter the yaw rotation.

Battery

  • Since 5 EDFs are used this semester, battery must be able to supply power to 5 motors.  

New PCB

  • All components must lie within the PCB.

System Block Diagram:

sys block

 

This is the Signal Block Diagram for the Millennium Falcon Quadcopter. To maintain stability during flight, the microcontroller will constantly read data from the sensors and the data would then be analyzed using a PID algorithm. The PID controller would determine how much power to supply to the ESCs to keep the Quadcopter in a stable position. The ESCs are directly connected to the Electric Ducted Fans and will control the speed accordingly. The microcontroller will be setup with a bluetooth module for communication with any mobile device. As an alternative to bluetooth communication, an RF transceiver will be connected to an input pin of the GPIO. A Remote Controller will be designed to communicate with the RF transceiver to control the quadcopter. The advantages of using radio communication instead of bluetooth communication is that radio waves are capable of travelling much longer distances than bluetooth. A 14.5 V LiPo battery will be used to supply power to the device.

Interface Definition:

Resource Map

MultiWii 328p Bluetooth ESC LED
1 3.3V Vcc
2 A0
3 A1
4 A2
5 AX1 Vin
6 AX2(RX1) RXD
7 AX3(TX0) TXD
8 AX4/D3
9 BAT
10 D10 Front Right ESC
11 D11 Rear Right ESC
12 D12 Side ESC
13 D2
14 D3 Rear Left ESC
15 D9 Front Left ESC
16 D13
17 LCD
18 PIT
19 PSE
20 PWR
21 ROL
22 THR
23 YAW
24 GND GND GND

 

Based on last semester’s resource map, the pin connections for the components will be similarly placed with addition to the 5th ESC that will be used for yaw control. The LED is moved to Auxiliary Pin 1 to make room for the 5th ESC. Pin layout for the sensors are not needed since they are embedded within the microcontroller.

 

Manufacturing Design:

Lightshow

  • Mount neopixel light ring under the battery casing.

Electric Ducted Fan

  • A 5th fan will be purchased and mounted on to the side of the Millennium falcon quadcopter.
  • An additional bracket will be designed on Solidworks and 3D printed.

Picture of Electric Ducted Fan (EDF):

Fan1

Picture of prototype EDF bracket:

Fan2

Orientation (Alternate solution for yaw control)

  • A series of case studies will be performed in order to determine an accurate angle to tilt the ducted fans.
  • Additional brackets may be designed and 3D printed if necessary to replace the current ones.

Battery Protection

 

  • A protective case will be designed on Solidworks and 3D printed. The case will be dimensioned to fit the applicable battery which will be used.
  • The case will be tested in order to determine if it can withstand impact without damaging the battery.

Picture of battery enclosure prototype:

Battery case prototype

 

  • A lid to close off the battery will be designed using Solidworks and be 3D printed. The lid will be designed to have landing legs added or removed. The lid and legs will be tested if they can support the Millennium Falcon quadcopter.

Picture landing leg prototype:

Legs

 

Printed Circuit Board

  • PCB will be laid out and have components properly mounted on.
  • PCB shall be mounted on to the current Millennium falcon frame.

Shell Casing

  • Shell will be modeled to look the the Millennium Falcon. Techniques used in prior semesters will be used such as using foam to fabricate the mold and then vacuumed. Previous semester reference
    • Additional brackets will be designed and 3D printed in order to be added onto the current frame which will serve as mounting brackets for the shell.
    • Holes will dimensioned to be bigger in order to make more space for the ducted fans.
    • A 5th hole will be cut out in order to make space for the additional bracket and ducted fan.

Picture of Millennium Falcon prototype shell:

MF Shell

 

 

Design and Unique Task Descriptions:

Task: Landing Legs must be able to support more than the estimated mass of the quadcopter.

Solution: Manufacture legs of best material in mass and strength combination.

 

Task: Test wireless control capabilities.

Solution: For bluetooth and RC control, test signal strength for best control.

 

Task: Power complete quadcopter electronics system.

Solution: Upon quadcopter completion, choose a battery best fit for quadcopter.

 

Task: Create quadcopter stability during flight.
Solution: Test EDFs thrust capability and trial and error placement and direction of EDF .

 

Cite references:

  1. Huynh, Tien-Phuc. “UFO Shell’s Production.” Arxterra. N.p., 6 Dec. 2015. Web. 18 Feb. 2016. <https://www.arxterra.com/ufo-shells-production/>.
  2. Arechiga, Danny. “Level 1 Requirements.” Arxterra. N.p., 16 Sept. 2015. Web. 11 Feb. 2016. <https://www.arxterra.com/level-1-requirements-4/>.
  3. Hatori, Ayaka. “Arxterra | Mission Objective and Level 1 Requirements.” Arxterra. N.p., 18 Mar. 2015. Web. 11 Feb. 2016. <https://www.arxterra.com/mission-objective-and-level-1-requirements/>.
  4. Hatori, Ayaka. “Mission Objective and Level 1 Requirements.” Arxterra. N.p., 8 Mar. 2015. Web. 11 Feb. 2016. <https://www.arxterra.com/ufo-intro/>.
  5. Vo, Tuan, and Elaine Doan. “Level 1 Requirements.” Arxterra. N.p., 21 Apr. 2014. Web. 11 Feb. 2016. <https://www.arxterra.com/level-1-requirements/>.

Spring 2016 AdBot Preliminary Design Documentation & Plan

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AdBot is a rover that will climb stairs.

Preliminary Design Document

By Dang Le, Project Manager, and Don Tran, System Engineer

  • Dang Le (Project Manager)
  • Don Tran (System Engineer)
  • Muhammad Ali Siddiqui (Electronic Engineer)
  • Muhammad Maqbool (Manufacturing Engineer)

Program Objective/Mission Profile
The customer wants a stair climbing robot to advertise his company in front of a building, and wants wireless steering using the Arxterra app for smartphones. We will give the customer Bluetooth. We will design the rover by May 14, 2016 around a $400 starting budget. The customer wants to use any parts available in the Electrical Engineering department or from the previous semester’s RoSco. We will document our thinking across the semester. The mission profile will be a test course consisting of the 9 steps in front of the USU building, then the concrete path clockwise leading down some inclines back to the bottom of the stairs. The images below show the bird’s eye view, front, and side of the test course.

AdBotRoute FrontUSU LeftUSU

Project Program Requirements

Level 1 Requirements
1. The project involving making AdBot and the blog posts shall be completed by 5/13/2016, which is last day of this 400D course:
2. The budget shall be $250, which is an estimate of most parts needed.
3. AdBot shall follow CSULB regulations for activities and for advertising.

4. AdBot shall travel 160 feet on concrete. This distance is the length of the test course counting inclines and stairs.
5. AdBot shall travel up 9 or more steps. The stairs in front of the University Student Union building consists of 9 4.3″x16″ steps.
6. AdBot shall use the Arxterra application for smartphones.
7. AdBot shall protect its hardware from rainfall and from a 50 psi water sprinkler.
8. The rover shall have at least one 3D-printed wheel, track, or parts.

ADVERTISING/PUBLICIZING EVENTS
All programs must be properly scheduled, confirmed and cleared prior to any notice or advertising of the event. All advertisements must include the sponsoring organization, name of program, date, time, location and contact information. Advertising in the USU of events hosted in the University Student Union and Soroptimist House require posting approval by ASI Communications, USU-235.

Level 2 Requirements

Level 1 requirements below are the same as the ones above, but restated.

Mission

L1: The primary focus of AdBot’s design is to make sure that it shall be able to travel up and down stairs in order for it to complete the test course that the president and division manager laid out.

  • The front of the University Student Union building consists of nine 4.3″x16″ steps. AdBot shall be able to travel up and down at this 15-degree incline.
  • AdBot shall be operational approximately 30′ from the smartphone-controller when no obstacles are obstructing. HC-06 Bluetooth receiver is rated for approximately 30 feet.
  • AdBot shall lift its front end at least 4.3 inches with the use of two servos.
  • The time to complete one circle of the test course shall be approximately sixteen minutes, at this point. This is time does not consider longer times going up stairs. For now, the following calculations are guessed for the 64 rpm free run speed, 800 mA stall current motors.

Budget

The budget shall maintain a low cost. The cost shall stay below $216 to $366. RoSco last had problems with 3D-printing driving up their costs from $216 to $366, and some cost was having to even pay for printer errors and problematic parts.

  • RoSco’s four motors and six servos uses 3 to 6 V input. The current 7.2 V battery is capable of driving those parts. It shall be used while prototyping AdBot.
  • It is important for AdBot that the amount of power it uses shall allow it to run for the proper length of time. The best case is it can travel the test course laid out one or more times. The current motors have a free run speed of 64 rpm and a stall current of 800 mA. When torque is calculated, then one can find the exact total power consumption. http://www.me.mtu.edu/~wjendres/ProductRealization1Course/DC_Motor_Calculations.pdf

AdBot shall have one or more 3D printed wheel, tracks, or parts. The manufacturing division within the company focuses on 3D modeling and 3D printing.

  • AdBot shall use ABS plastic against other types. When printed correctly, this material is durable. One ABS plastic track on RoSco can withstand 150 pounds placed upon it.
  • AdBot shall keep its tracks from coming off while AdBot is moving. The current treads are approximately 12 inches when loose. AdBot’s design will consider stretching the treads or shielding it around the wheels. The treads may also be cut and melted to a shorter size.

Size

AdBot shall build upon RoSco’s design while conforming to CSULB regulations for activities and for advertising.

  • AdBot shall fix the loose tracks that was the main problem that RoSco had.
  • RoSco protected its components from direct rainfall, such has having a waterproof chassis and motors inside its legs, but the cover for the chassis did not close its gap fully. Therefore, AdBot shall also protect its hardware from both rainfall and puddles, for as long as its mission duration. One solution would be using weatherstrip tape as one can cut it to exact dimensions.
  • AdBot shall remain under 3 feet. The regulations for activities and advertising, in short, issues that signs must not exceed 3×3 feet. The height of the rover and the stake together will be designed under this height.

Feature

AdBot shall require the use of the Arxterra application on smartphones and the Arxterra Control Panel on the internet browser to control it.

  • Arxterra has a setting called community where controls are on the Control Panel at http://cp.arxterra.com/# and the camera on the smartphone turns on for visible capability. AdBot shall be able to move the camera around separate from its main body. The solution is to have a pan, tilt system, because the firmware code for Arduino has a pan and tilt function.
  • The smartphone shall have internet access. Arxterra’s Control Panel does not connect to the phone when the phone is not on a wireless internet network.

Timing

The project involving making AdBot and the blog posts shall be completed by 5/13/2016, which is last day of this 400D course.

Design Innovation
AdBot’s design will take to consideration a maximum load weight placed upon the tracks or the chassis-to-track connections in order to keep the tracks aligned. AdBot may or may not have a pan and tilt system holding a picket sign. The priority is to make AdBot work and have enough power to complete the mission profile.

Systems Design
System Design Diagram
AdBot’s tracks shall have up to 1 motor each. It will have free spinning wheels on opposite ends of the tracks. Parts from the old PCB will be reused. More blocks will be added to the systems design as we learn more about the project.

Product Breakdown Structure
AdBot PCB
The PBS lists the software and hardware needed for a running prototype.

Manufacturing and Design

By Muhammad Maqbool, Manufacturing Engineer

The big tracks on each side of the robot consist of a total of four wheels, two in the back connected together with a steel rod and two in the front connected with another steel rod. We are thinking about using any spare leather belt so we don’t go out and buy it. on the belt we are thinking to layering wood patches so our track can have a firm grip which we will obtain through popsicle sticks. The wheels will be rotating at all times hence rotating the belt with it. As you can see the big tracks are attached to two small tracks called legs. The legs are attached to the gear system hence moving up while climbing up the stairs. The legs consist of four wheels total, two on each side.

For the wheels we will be needing reliable 3D printer, if not then we will be using the wheels from the old rosco as they are in good condition. Our main goal is to cut the cost as much as we can when it comes to the designing. So we can save money and buy some heavy duty motors and battery that can last longer once our robot performing its task.

The chassis and tracks shall be constructed after the dimensions are finalized in SolidWorks.

We shall use a 3D printer to print our desired components. ABS plastic will used to cut the cost to lower than $90.

Muhammad Maqbool shall obstain good 3D prints with the desired dimensions.

He will use Eagle CAD to design the PCB. The PCB will then be tested.

Small tracks on the AdBot will help it climb up, as it will be facing up while climbing up the stairs.

These are 3D models of AdBot:

4 5 6 7
2 1

Electronic and Test

By Muhammad Ali Siddiqui, Electronic Engineer

System Interface Matrix

Pinout1
Pinout2

The interface diagram shows the connections of the Bluetooth sensor, motor control board, and motors.

  1. Work with systems engineer to create interface definitions and to create functions/subroutines for microphone, speake
  2. r, camera, and graphics display unit.
  3. Create fritzing diagram from the interface matrix.
  4. Create fritzing diagram for custom servo controller board.
  5. Create pcb layout for the custom servo controller board.
  6. Work with systems engineer to determine the type of battery to be used.
  7. Perform tests and run simulations to determine suitability of sensors being used.
  8. Consult with the division manager to determine audio and video encoding to be used for the AdBot.
  9. Shall be testing battery the to determine if it is capable to complete task 100% with 55 to 65% of battery consumption.

Unique Task Descriptions

By Muhammad Maqbool, Manufacturing Engineer

1. Create 3D models using solid works and obtain good 3D prints using 3D printer. (5 weeks)
2. Manufacture PCB design using EagleCAD. (2 weeks)
3. Run simulation of AdBot in solidworks. (3 weeks)
4. Research which material is best for the Wheels, the body and the arms of AdBot. (3 weeks)

Preliminary Plan Document

By Dang Le, Project Manager

The AdBot diagram of work breakdown structure below shows individual responsibility during the project. Don is responsible for Mass report, Power report, Arduino coding, and verification test plan and report.
Muhammad Ali Siddiqui is in charge of PCB design, build breadboard, and coding for the motors, servo, Bluetooth, camera, audio, etc.
Muhammad Maqbool is responsible for 3D modeling and solid works design for chassis, wheels, and track.
Dang Le is responsible for project update, photo/video editing and order parts. He will take some work load from manufacturing like soldering components on PCB, cable tree wiring, and assembly AdBot.

Work Breakdown Structure

WBS-72dpi

This work breakdown structure exists to provide task coordination in this project team. Each block indicates the responsibility of only one engineer designated it.

Project Schedule

By Dang Le, Project Manager

We have been working on the prototype of the AdBot. Muhammad and Don was testing the motor, servo, and Bluetooth device. In the mean time, Muhammad Maqbool was designing the wheels and chassis. We will test our prototype when everything ready and fully assembled. Using the Projectlibre tool, we should see our task move along with our schedule as we planned or not. This schedule allowed us to focus closely on each stage as we move on until the completion date. This is our final schedule in planning to complete our project.

Top level Schedule

projectschedule1-72dpi

projectschedule2-72dpi

The schedule begins on Feb-12 and ends on May-13. Both planned and actual remaining time will be measured in days.

System/Subsystem Level Tasks

System-subsystem-72dpi

The system and subsystem level have defined by our work breakdown structure

Burn Down and Project Percent Completion

BurnDown-72dpi

The burn down chart is measured by weekly progress.

System Resource Reports: Power Report, Mass Report, and Cost Report

Power Report

Power Report MAS

The projected values on the power report are all estimates based on research on components. Since the maximum current allowed was undefined, a reasonable value was chosen for the project allocation. By the end of this week, measured free and stall current for servos and motors will be added. This requires using an Arduino, spring scale torque-measurer, and more.

Mass Report

Mass Report MAS

The projected values on the mass report are estimates based on research on components, and since the upper weight limit was undefined, the projected weight seems reasonable. By the end of this week, actual weights will be included.

The mass report came about this way:
1. Label all the parts in the AdBot blueprint/mockup drawing or check the PBS.2. Search available components from retailers/Sparkfun.
(Parts may change depending on torque decisions, etc.)
3. Search for model datasheet PDF files on Google to find component masses.
4. Estimate the mass for 3D-printed parts.

Project Cost Estimate

Cost Report

The cost report from 2/26 is replaced with an alternate cost estimate made earlier by Don Tran. A better table will replace this in a few days once midterms are completed. The table currently excludes four motors and four servos from RoSco. A prototype rover is being assembled and more idea about the handling of mass and load by the current motors will be found out.

Spring 2016 Pathfinder Preliminary Design Documentation

/in , /by

opp rover

By:

Peiyuan Xu                        (Project Manager)

Xiong Lee                          (Mission, System and Test Engineer)

Juan Acosta                      (MCU Subsystem and Control Firmware)

Tuong Vu                          (Sensors, Actuators and Power)

Lindsay Levanas             (Design and Manufacturing)

Table of Contents

Program Objective/Mission

By:  Peiyuan Xu (Project Manager)

The spring 2016 Pathfinder Rover was inspired by the design of NASA’s MARs Exploration Rover-“Sojourner”. The purpose of this Rover is to explore the beauty of CSULB campus at night in a self-sufficient way. The Pathfinder is allowed to have the solar panel charging the battery for up to 8 hours during the day time. Then the customer will spend 4 hours at night walking and exploring with the Pathfinder . The customer can use Arxterra control panel on the PC to navigate the Rover by using the cursor to click a point on the map. This generation of Pathfinder Rover is designed to test and implement SLAM (Simultaneous Localization and Mapping) technology for autonomous vehicles.

Program Requirement

  1. The Pathfinder project must be completed by May 2, 2016, the last day of EE 400D class. (From the Syllabus here)
  2. The cost of the project should be limited to $800 (Need customer verification)
  3. The Project Final Documentation must be turned in by April 25th, 2016. (From the syllabus here)

Project Level 1 Requirement

  1. The pathfinder shall be able to explore the terrain at CSULB campus at night
  2. The speed of the pathfinder shall be slower than human walking speed and faster than the Sojourner rover.
  3. The pathfinder shall be able to explore the campus at an interval of 8 hours charging (during day time) and 4 hours run time (during night time).
  4.  Sealed electronic enclosure required to protect electronics from dust
  5.  The pathfinder shall be self-sufficient by using 3 solar panels
  6.  Sealed pan and tilt system for the Android phone/Google Tango Tablet.
  7.  The tango will be able to gather depth perception data and send it to the Arxterra control panel.
  8. The pathfinder shall be able to go to the place wherever the cursor points on the Arxterra control panel.
  9. The customer shall be able to see what the rover sees on the camera

Source Materials

  1. Fall 2014 Pathfinder Preliminary Design here
  2. Curiosity Rover Wiki here
  3. Getting start with Project Tango API here
  4. Google Project Tango Overview here
  5. Project Tango Indoor Mapping here
  6. Project Tango Intro to Point Cloud here
  7. Project Tango Intro to Depth Perception here
  8. Autonomous Quadrotor Flight Based on Google’s Project Tango here

Design Innovationcreativity3

creativity1 creativity2 creativity4
creativity6

 

System Requirements (Level 2 Requirements)

By:  Xiong Lee (Mission, System&Test)

  1. In order to navigate through the terrain of the CSULB campus, the suspension and chassis will be designed to clear at least twice the diameter of the wheel. (found in the mars rovers) The Rocker Bogie design will be implemented to achieve a clearance of at least two times the diameter of the wheel.
  2. Due to the customer’s request to not go faster than walking speed, the pathfinder will not exceed 3ft/sec (about 2 mph).
  3. The motors will be calculated to ensure it will not go faster than 3ft./sec.
  4.  Results: TBD
  5.  The motors will be able to climb up an incline of 45 degrees. An experiment will be conducted to see what motors we need to get to achieve this requirement.
  6. The pathfinder will go faster than the curiosity rover (3in/sec). The motors will be calculated to go faster than 100m/sol.
  7. To explore the campus for 4 hours at night, we will install the battery or batteries to handle this run time.
  8. The solar panel will be able to charge the pathfinder 8 hours so it can finish its mission of running for 4 hours.
  9. The electronic enclosure will be made out of ABS plastic material to protect the electronics.
  10. The pan and tilt system will be 3D printed and designed like the previous semester.
  11. The pan and tilt system will be slightly modify to accommodate the dimensions of the Google tango tablet.
  12. The Tango tablet will need to be able to communicate with an app to receive data from its point cloud to the control panel.
  13. To see whatever the rover sees, LED lights will be installed onto the pathfinder, so the customer can see whatever the rover is in front of.
  14. To make sure we don’t waste power to the LED lights when it’s still got enough light to see, there will be a switch and light sensor to turn the lights on and off.
  15.  The pathfinder will go from 0.5 to 4 meters when clicked on the control panel. (The tango can scan approximately from 0.5 meters to 4 meters).

Source Materials:

  1. Mars Exploration Mission (Overcoming Obstacles) here
  2. Bogie Runt Rover (with chassis and Rocker Bogie Suspension) here
  3. Study Compared Older and Younger Pedestrian Walking Speed here
  4. The Mars Science Laboratory Mission here
  5. Arxterra Mini-Rosco Pan and Til System here
  6. Google Project tango overview here

Product Breakdown Structure

pbs

 

The main parts from hardware to software of our pathfinder is shown in the above PBS (product breakdown structure). Starting from the hardware, the chassis needs to be chosen to be able to handle the terrain in CSULB campus. One of the better idea we got was to use a rocker bogie system similar to the mars rovers. (Curiosity, Spirit and Opportunity, and Sojourner). The mars rovers are able to handle the harsh terrain of mars so choosing this suspension system would be a good choice to start the design. A pan and tilt system need to be installed to the pathfinder so we can scan the area with our Google Tango and android phone to be able to gather data on how far everything is. The solar panel needs to be able to charge up our battery during the daytime so we can have the Pathfinder running for good amount of time at night. Lastly, the software needs to be able to control everything on the hardware side to make sure the pathfinder will run correctly.

Electronic System Design

By: Juan Acosta (MCU Subsystem and Control Firmware)

Tuong Vu (Sensors, Actuators and Power)

System Block Diagram

system block diagram pathfinder

In the system block diagram, it shows how everything is connected to be able to control the pathfinder. The pathfinder will be running on mainly the arduino. The arduino will have a bluetooth module to communicate with the android phone and the control panel. On the arduino, there is a motor shield that will be able to run the motors in forward or reverse. It will also control the servos of the pan and tilt system to scan 180 degrees. To run the arduino, a battery will be installed and charged with the solar panels. Our main component is the Google Tango which will be use to 3D scanning the environment and send the depth perception data to the PC which will then give command to Arduino to control the Rover.

Subsystem Requirements

  1. The solar panels will have to charge the batteries for the Pathfinder in order to allow a 1:2 run ratio. (ex. 30 mins. run, requires 60 mins. charging time.) Current candidates require more testing of motor current draw.
  2. The solar panel(s) will resemble the Arxterra shape logo. In order to achieve this, we will be using multiple solar panels. (minimum of 3, maximum of 6 for weight and size concerns.)
  3. The Arduino Mega will act as a Voltage controller for the motor shield for the PWM supplied to drive the motors.
  4. The Arduino Mega will act as a charge controller in order to prevent the batteries from over charging and generating unwanted heat.
  5. The software code will allow the Pathfinder to drive forward, turn left or right, and rotate 90, 180, or 270 degrees.
  6. The Arduino UNO will control the pan and tilt servo for field of view through the android phone.
  7. The android phone will be used to communicate with the Bluetooth component and the Arxterra Control Application.

Power Flow Diagram

Power Flow Diagram

Battery is going to be the source of the power for the pathfinder, and many type of battery can be used in this application. The battery has to be able to deliver enough voltage and current to both the Arduino and motors & servos. High voltage has the potential of damaging the motors & servos and Arduino. Thus, buck regulators are installed in order to lower the incoming voltage from the battery. Over charging the circuit will result in damaging the battery, so a charge/discharge circuit will govern when the battery will connect to the solar panel or not.

Code Block Diagram

code block diagram

The Code Flow Chart shows how the Pathfinder will operate. It will be able to operate manually or on autopilot. Manually controlling the Pathfinder will involve the Android phone being used as a medium between the Arxterra Control Center and the Pathfinder’s commands. On the other hand, the autopilot feature will involve the Point Cloud System. Based on the depth perception data from the Google Tango tablet, communication will occur between the Tango tablet and the Arduino and allowing the pathfinder to voyage to set destination.

Interface Definitions

interfacematrix

The interface matrix above details the connection between the microcontroller and the motor- shield, solar panels, and Bluetooth module. It also indicates that the Arduino UNO will use pins to control a servo, monitor voltage, and act as a charge controller by monitoring the solar panels.

Mechanical Design

By:  Lindsay Levanas (Design and Manufacturing)

Mechanical Design

The above model illustrates Pathfinder’s conceptual design based off of both the level 1 and level 2 requirements. As stated in the level one requirements, Pathfinder must be solar powered, hence the thin rectangles on the top of the body.  A pan and tilt system for either an Android phone and Tango tablet is required and is modeled as a box (the length and width of an Android phone2) on a pole. The box will contain the phone (and Google Tango) and the wires will run down the inside of the pole into the body of Pathfinder. Pathfinder’s body then will house the electronics in a sealed enclosure as defined in the level 1 requirements. Lastly, Pathfinder will utilize a rocker bogie suspension system as a level 2 requirement to meet the level 1 requirement of being able to explore the CSULB campus

Source Materials

Axterra Website here

Android Phone size  here

 

Design and Unique Task Description

Power System Design

By:  Tuong Vu (Sensors, Actuators and Power)

Here are the specifications of our motors, wheels, and chassis.

motors (6) 140 Pre-wired motors
wheels (6) 2.55” Press Fit Wheels
Chassis (1) ABS Robot Chassis

Our servos with be the same servo used by the previous team. Using lithium battery will reduce the charging time of our rover, the specification of the battery is as the following (Tenergy 31016 Lithium Li-Ion 18650 11.1V 4400mAh Battery Pack).  We are planning to use two of them, one for two front wheels and the other for the two wheels in the back.  Our solar panel is going to be Solar Panel – 9W; we need 3-4 panels to have enough voltage to charge the batteries. Using two DC-to-DC (4.5 – 45V to 3.0 – 35V) Converter Module Board Step Down Transformer Module – BLUE, we can step down the incoming voltage from the battery.

Power system design

 

Source Materials

  1. Battery we need is here
  2. Dimension of the solar panel here
  3. DC to DC converter module board here

More on Mechanical Design

By:  Lindsay Levanas (Design and Manufacturing)

  • Rocker bogie design

    • Structure must be such that Pathfinder’s chassis can clear twice the wheel’s diameter. To do this, the distance between the bottom of the chassis and the bottom of the wheel must equal twice the wheel’s diameter.
    • The struts must be calculated to allow for level orientation of the chassis. Back-of-the-envelope calculations used for the 3D model are provided below however more formal calculations will be needed for the final design.
  • Rocker Bogie back of envelope
    • Material and cable tree for the rocker bogie suspension system will need to be defined.

  • Solar panel layout and shape

solar panel designOnce the power systems engineer has selected the solar panels, they will be balanced on the top of Pathfinder in the shape of the Arxterra logo. The rough sketch the 3D model is based on is shown above, however more accurate measurements will need to be made once the solar panel dimensions are known.

  • Pan and tilt system

    • The materials, dimensions and location of the pan and tilt system will be based around the mapping device (either Android phone or LIDAR) selected for Pathfinder.
    • The servos will be housed inside the main body of Pathfinder.
    • Wires will be contained inside the pan and tilt structure.

     

 

 

Spring 2016 3D SMD: Preliminary Design Document

/in /by

By: Bao Loc Doan (Project Manager)

Christine Vu (Systems Engineer)

Henry Nguyen (Electronics Engineer)

Nasser Alsharafi (Manufacturing)

Table of Contents

Program Objectives/Mission Profile

by Bao Loc Doan (Project Manager)

Program Objective Statement

When humans manually pick and place surface mount components onto a printed circuit board (PCB), there are problems with human accuracy and time efficiency. A pick and place surface mount device (SMD) is an automated device that can populate a PCB with surface mount components (resistors, capacitors, and IC chips) by referencing a Gerber file through the use of software. The pick and place SMD machine will be able to pick up the surface mount technology (SMT) components from 8 mm reel feeders and an integrated circuit (IC) tray and place the components down at the correct location until the board is finished. The customer has expressed the desire to create a pick and place SMD machine that can populate surface mount components as small as 0402 on all EE400D boards of Spring 2016 with the same specifications as the Madell Corporation Model DP2006-2.  The customer has expressed the desire to keep the budget of the project below $650 and finished before the end of Spring 2016.

Mission Profile

Once a gerber file provided by any project from EE400D up until Spring 2016 is uploaded, the pick and place SMD machine shall begin populating SMT components from four 8 mm reel feeders and one IC tray onto the PCB. The smallest SMT component that will be placed is component size 0402. The pick and place SMD machine will be modified from a Makeblock XY plotter and replicate the error specification of the Madell Corporation Model DP2006-2.

Requirements

Level 1 Program/Project Requirements

by Bao Loc Doan (Project Manager)

To satisfy our customer, a list of requirements that our end product needs to meet were created. These requirements will move the design forward and provide traceability to our program objectives and mission profile.

  1. The pick and place SMD machine shall be able to assemble all EE400D PCB’s by the end of Spring 2016.
  2. The pick and place SMD machine shall pick up a component and place down a component with a maximum of 0.05 mm error (specification of Madell Corporation Model DP2006-2).
  3. Software for the pick and place SMD machine shall accept all Gerber files of EE400D projects up until Spring 2016.
  4. The pick and place SMD machine shall have four 8mm reel feeders and one IC tray.
  5. SMT component size 0402 shall be the smallest component that the pick and place SMD machine can pick up. 
  6. Total cost of finished project must be under $650.
  7. Deadline to complete the pick and place SMD machine shall be before the end of Spring 2016.

Level 2 System/Subsystem Requirements

by Christine Vu (Systems Engineer)

Level 2 System and Level 2 Subsystem Requirements are listed below. The process of forming requirements is not only crucial to the overall design of the project but also difficult to form due to the customer’s needs and the nonlinearity of designing. Through many revisions, the level 2 requirements were officially determined. Because this project is new to the Arxterra blog, references were obtained through scholarly journal research and outside resources other than the Arxterra blog.

Source Material:

Arra, M. , Geiger, D. , Shangguan, D. , & Sjöberg, J. (2004). A study of smt assembly processes

for fine pitch csp packages. Soldering & Surface Mount Technology, 16(3), 16-21.

CadSoft Computer GmbH and CadSoft Inc. (2011). EAGLE Freeware. Retrieved from:

http://www.cadsoftusa.com/download-eagle/freeware/

Changzhou Douwei Electric Co. Ltd. (n.d.). 42BYG Stepping Motor. Datasheet.

Makeblock. (2014, June 9). XY Plotter 2.0 How it works? Retrieved from:

https://www.youtube.com/watch?v=gY0xMYrWBDg

Panasonic. (2014, Feb. 4). Precision Thick Film Chip Resistors. Datasheet.

Shenzhen Maker Works Technology Co., Ltd. (2013). X-Y Plotter Robot Kit. Retrieved from:

http://www.makeblock.cc/xy-plotter-robot-kit/

TCI Precision. (2005). Blanchard Grinding. Retrieved from: http://tciprecision.com/machine-ready-blanks/capabilities/Blanchard%20Grinding

Telecommunications Industry Association. (2001). TIA/EIA-568-B.1: Commercial Building

Telecommunications Cabling Standard.

VBsProjects. (2014, July 12). Homemade SMD Pick and Place Machine – complete cycle.

Retrieved from: https://www.youtube.com/watch?v=CRSLbo_8nTQ#t=7m34s

Notes on Requirements:

L2 – # – Level 2 System Requirements (i.e. L2 – 1)

L2 – #x – Level 2 Subsystem Requirements (i.e. L2 – 1a)

L2 – 1 Working area must be within 12.2”x15.35” (310mmx390mm) based on the Makeblock X-Y Plotter.

Explanation: The MakeBlock X-Y Plotter Robot Kit design specifications indicated the working area size as shown above (Shenzhen Maker Works Technology Co., Ltd., 2013). The working area is the area that the motors can move. This requirement will be verified through the use of a measuring tape tool. Tolerances will be taken account depending on the measuring tape that will be used.

L2-1a   Working Area shall fit a 4″ x 3.2″ PCB for EE400D students.

Explanation: EE400D Students will be using EagleCAD software to design their PCB.

The free version limits the PCB design size as 4” x 3.2” (CadSoft Computer GmbH and CadSoft Inc., 2011). This can be verified by the use of a measurement tape tool.

L2-1b  Surface to hold PCB shall be smooth with dimension tolerances to ±.001″, parallelism to .001″, and flatness to .001″.

Explanation: The process to place SMT components will begin with the application of solder paste by hand. This requires a very smooth surface that may require Blanchard grinding. These tolerances were taken from industrial Blanchard grinding standards (TCI Precision, 2005). This will be verified from the company that we plan on using.

L2-1c   PCBs laid out for assembly shall be on a surface at 0° with respect to the floor. A test shall be used to determine a safe tolerance.

Explanation: To improve precision, it is important to ensure that the machine will run in a straight line and parallel to the floor. This will keep the SMT components from falling off the PCB. A digital leveler will be used. Tolerances will depend on the leveler used.

L2-1d  All wires shall refrain from contact with the working surface.

Explanation: The Makeblock X-Y Plotter lacks the placement of wires. During plotting, wires are touching the surface (Makeblock, 2014). This should be avoided due to the addition of more wires, reel feeders, and IC trays in the working area. Wires dragging against the surface may also cause problems with wire protection.

L2-1e   All wires using RJ25 connectors shall have a minimum bend radius of 4x its diameter.

Explanation: The pick and place SMD machine has repetitive movement, where a vacuum system will pick up a SMT component and place it down a PCB one at a time. Since wires will be moving along the vacuum system, repetitive movement may affect the lifespan of the wires. Therefore, a general rule-of-thumb to prevent wire fatigue is to set a minimum bend radius of 4 times its diameter (Telecommunications Industry Association, 2001). The bend radius shall be measured from the start of the curve to the end of the curve using measuring tape. Tolerances will depend on the tool being used.

L2-1f   A clamping system shall hold all PCBs for EE400D students with maximum size 4″ x 3.2″.

Explanation: A clamping system will provide stability when the vacuum system is placing down the SMT components and indicate the maximum PCB size 4” x 3.2”, which is the limited PCB size for the free version of EagleCAD (CadSoft Computer GmbH and CadSoft Inc., 2011). This will be verified by clamping a 4” x 3.2” PCB. The clamped PCB should not be able to move once the machine is operating.

L2 – 2 The pick and place SMD machine shall pick up and place down all required integrated circuit chips according to EE400D PCB’s provided up until Spring 2016.

Explanation: The purpose of a pick and place SMD machine is to assemble a PCB design given by EE400D Students. It is important to note that integrated chips will also be placed down. This will be verified by the provided Gerber file.

L2-2a   A vacuum system shall pick up all required IC chips according to EE400D PCB’s provided.

Explanation: A vacuum system is the subsystem that will be used to pick up SMT components such as the integrated circuit (IC) chip. It also indicates that a vacuum system must be strong enough to hold the IC chip. This will be verified by testing the worst-case scenario, where the heaviest IC chip will be picked up by the vacuum system.  Explanation of the duration will be indicated in the next requirement, L2-2b.

L2-2b  Duration of suction to pick up IC chips shall begin from picking at IC tray to the placement on the PCB.

Explanation: Although picking up the SMT components are lightweight, it may be important to verify the duration of how long the vacuum system takes to pick up a component and place it on the PCB. A stopwatch will be used to time the process.

L2-2c   A solenoid valve shall close airway of the vacuum tubing each time IC chips are placed down.

Explanation: The vacuum system will be controlled through the opening and closing of a solenoid valve. This can be verified by testing the software to control the solenoid valve picking and placing the IC chip. This requirement is also noted for the rest of the SMT components in L2-8b.

L2 – 3 Pick and place SMD machine shall self-correct all orientation of IC chips before placement.      

Explanation: This requirement is to ensure that the pick and place machine is able to auto-orientate IC chips in case the chip is placed incorrectly on the IC tray. This can be verified through testing of the worse-case IC chip.

L2-3a   A sensor area shall detect the number of pins on IC chips.

Explanation: A feature that may be included to support our pick and place SMD machine is to create an area to correct the configuration of the IC chip when it is removed from the IC tray. This idea was based on one of a homemade pick and place SMD machine (VBsProjects, 2014).

L2-3b  In order to keep suction of the IC chip after pick-up, all IC chips shall be rotated about the A-axis.

Explanation: As stated in L2-3a, it is important to note how the IC chip will be corrected. That is, a motor may be used to move about the A-axis. VBsProjects (2014) demonstrates how the IC chip will be corrected. This will be verified by test – an IC chip will be picked up by the vacuum system and taken to the sensor area, where it will be corrected.

L2 – 4  Makeblock X-Y Plotter motors shall be modified to a maximum of 0.05 mm error.        

Explanation: The Makeblock X-Y Plotter online specifications indicate that the precision error is 0.1 mm (Shenzhen Maker Works Technology Co., Ltd., 2013). Calculations may be verified based on the distance between the SMT mounting holes (Arra etc., 2004).  

L2-4a   Resolution of all axes motors shall be less than 1.8°/step.

Explanation: The Makeblock X-Y plotter uses 42BYG Stepper motors to control the x-axis and y-axis, which indicate a resolution of 1.8°/step (Changzhou Douwei Electric Co. Ltd., n.d.). To improve the precision, a possible solution is to switch the stepper motors into better ones. This may be verified through the use of datasheets.

L2-4b  Z-axis motor shall move the vacuum system at 90° with a tolerance of 1° with respect to the floor.

Explanation: The Z-axis control on the Makeblock X-Y plotter uses a servo motor that moves up and down at an angle (Makeblock, 2014). If the z-axis is not modified, then the vacuum tubing may be bent and the vacuum system will not function properly if it is picking up the SMT components at an angle.

L2 – 5 Software shall translate all Gerber files from EE400D PCB’s to G-Code files.     

Explanation: The Makeblock X-Y Plotter plots using G-code files. Arduino sketches have already been made to control the motors.

L2-5a   Software shall include all x-y coordinates for pick and place SMD machine to read.

Explanation: G-Code will be viewed on CNCViewer, a program that can present the locations of the SMT components on a PCB.

L2 – 6: All SMT resistors and capacitors shall remain in cut-tape of the reel feeders until the vacuum nozzle is ready to pick up the component.     

Explanation: This requirement is to acknowledge that the reel feeders are secure and in place. This will be verified using a checklist – determine whether the vacuum nozzle moves other SMT components when the nozzle picks up one SMT component, determine whether the motors cause vibrations of the working area, and determine whether the SMT components will be isolated while the system is placing the components.

L2-6a   Reel feeders shall be placed within working area, 12.2”x15.35”(310mmx390mm).

Explanation: Because our working area is confined to the Makeblock X-Y Plotter Robot Kit (Shenzhen Maker Works Technology Co., Ltd., 2013), the vacuum system must be able to reach the SMT components. Therefore, the reel feeders must be placed in an area where it is reachable.

L2-6b  Bracket to hold cut-tape of the reel feeders shall be higher than 1.10 mm.

Explanation: The reel feeder tape specifies the tape thickness to be 1.00 ± 0.10 mm (Panasonic, 2014). In order to hold the reel feeders in place, the bracket should be higher than this. This can be verified by placing the reel feeders in the bracket.

L2-6c   Micro servos shall automate all reel feeders.

Explanation: The pick and place SMD machine shall be automatic; therefore, a motor would be used to control each of the reel feeders. A trade-off study will be conducted on micro-servos.

L2-6d  All micro servos shall remove plastic covering from the reel feeder.

Explanation: A solution to control the feeder is to have a pulley attached to the micro servos. A specification on a pulley shall be determined.

L2 – 7: IC tray shall store all IC chips required for one PCB assembly.    

Explanation: The worst-case scenario will be used to determine the size of the IC tray.  

L2-7a   IC tray shall be placed within working area, 12.2”x15.35”(310mmx390mm).

Explanation: Similar to the L2-6a, the vacuum system must be able to reach the working area of the Makeblock X-Y Plotter Robot Kit (Shenzhen Maker Works Technology Co., Ltd., 2013).

L2 – 8: Vacuum system shall be able to pick up all SMT components as small as size 0402.

Explanation: This requirement was based on the customer requirement to pick up small components. This will be verified by picking up the SMT component size 0402.

L2-8a   Vacuum nozzle shall be smaller than 0.50 ± 0.05 mm.

Explanation: The nozzle size is based on the smallest component to pick up, which is 0402. According to the datasheet, SMT size 0402, 0.05 0.50 ± 0.05 mm (Panasonic, 2014)

L2-8b  A solenoid valve shall close airway of the vacuum tubing each time SMT resistor and capacitor components are placed down.

Explanation: Similar to L2-2c, a solenoid valve will be used to control the passageways of the vacuum tubing. A test shall be conducted to control the solenoid valve with ArduinoUno.


Design Innovation

Creativity Presentation

System/Subsystem Design

Product Breakdown Structure

By Christine Vu (Systems Engineer) and Henry Nguyen (Electronics Engineer)

Product Breakdown Structure


Figure 1. Product Breakdown Structure

The Product Breakdown Structure (PBS) shows all the functional blocks of our pick and place 3D SMD machine. The hardware is split into three different categories: Component Feeders, Vacuum Head, and X-Y Table. We will need a minimum of 4x micro servos to control our 4x 8mm reel feeders and an IC chip tray. The Vacuum head will consist of a vacuum to suction the components, a syringe or vacuum pen to pick up our components, a solenoid valve to block airflow and allow our components to be placed, and finally a stepper motor for rotation of the A axis. The X-Y Table is purchased from MakeBlock; however, we will need an aluminum surface table, slider rods, stepper motors, and calibration sensors to orientate our components. For software, we plan on using Arduino to program the Arduino Uno and Me Orion microcontrollers. Software must be able to convert Gerber files into G-code which can be read by our Me Orion microcontroller. We will need to be able to control all axis of our machine, the calibration sensor, component feeders, and solenoid valve through software.

Electronic System Design

by Henry Nguyen (Electronics Engineer)

Source Material

Me Orion:

Me Stepper Driver:

System Block Diagram

System Block Diagram

Fig. 2. System Block Diagram

The image above is the system block diagram for our pick and place 3D SMD Machine. We will have 4 stepper motors, 4 micro servos, a vacuum, and a solenoid valve as our actuators. The 4 stepper motors are used to control our axis on our machine. We will have a X,Y,Z, and A axis. The A axis is for the rotating our vacuum nozzle in order to orientate our integrated circuits in the right position to place onto our PCB. We will also have 4 micro servos to control our reel feeders. We are planning on using these servos to move our components forward after our machine picks up the component from the reel feeders. The solenoid valve is to control our vacuum. Our vacuum will be constantly running on a separate power source. The solenoid valve will close off the vacuum to prevent suction. This will allow our components to be placed onto our PCB after our machine picks it up.

Interface Definition

Interface Matrix

Fig. 3. Interface Matrix

The image above is the interface matrix for our pick and place 3D SMD machine. We will be utilizing an Arduino Uno, Me Orion, and Me Stepper Driver. Me Orion and the Me Stepper Driver came with our X-Y Plotter. This Me Orion is based off of an Arduino Uno, which will allow us to code using Arduino, Scratch. and AduBlock. We will be using this microcontroller because it has 8 RJ25 ports which will be useful for all of our actuators. The Me Stepper Driver will be used to precisely control our stepper motors by operating our motors in full, half, quarter, eighth, and sixteenth step modes. This modes can be easily changed using the built-in DIP Switch. We will need 4 Me Stepper Drivers in order to control all of our stepper motors on each axis (x,y,z,A).

Me Orion Schematic

Fig. 4. Me Orion Schematic

Me Stepper Driver Schematic

Fig. 5. Me Stepper Driver Schematic

Specification for  Me Orion:

Operating Voltage: 6-12V DC power;

Microcontroller: ATmega238;

Detecting Angle: prefer at 30 degree angle;

Dimension: 80 x 60 x 18 mm (Length x Width x Height);

Specification for Me Stepper Driver:

  • Max current: ±1.35A
  • Max motor drive voltage: 25V    
  • Note: Me BaseBoard max supply  voltage 12V
  • Logic voltage: 5V
  • Dimensions: 48mm*24mm(Length × Width)

Mechanical Design

By Nasser Alsharafi (Manufacturing)

In this part of the project for the XY plotter I am coming up with the design of a Reel Feeder. The main purpose of a reel feeder is to feed the machine with the surface mounted parts. The reel feeder is made of aluminum. The main function of the Reel Feeder wheel is to roll and pass on the parts to the Reel Feeder base, which then the parts will be picked up by the vacuum.

FeederReelAssembly

Fig. 6. Complete reel feeder assembly 3D model

Reel Feeder Base

Fig. 7. Reel feeder base

The base sheet of the reel feeder has four channels called the grooves in which the tape passes through. The base sheet of the reel feeder has a length of 270 mm and a width of 82 mm. Each of the grooves on the base sheet of the reel feeder has a width of 8 mm. The main function of the reel feeder is to guide the tape to the part of the feeder where the chip is first pulled and then picked by a vacuum pen. This action helps in preparation of the next chip. After, the chip is taken by the vacuum pen and is placed on the PBC board.

Reel Feeder Wheel

Fig. 8. Reel feeder wheel

Initial Sketch of Reel Feeder Base

Fig. 9. Drawing of initial reel feeder base

Currently, our reel feeder is manual, so there can be further improvements by making the reel feeder automatic. In order to make the reel feeder automatic, I have to design a mounting bracket for 4 micro-servos. Each channel has single micro-servo to pull back the tape while pushing the reel forward. This will be implemented by working with Henry Nguyen to control the micro-servos.   

Design and Unique Tasks

By Henry Nguyen (Electronics Engineer)

  • Work with our X-Y Plotter and given programs in order to see how to control our actuators through software (02/19/16 – 02/28/16).
  • Research Flatcam which can take Gerber files and generate G-Code for isolation routing.
    • This is for our precision software that will tell our machine exactly where to pick and place components (02/19/16 – 02/28/16)
  • Look for local connections and prices for our aluminum surface table by 02/28/16.
  • Review DIY tutorials on how to configure an aquarium pump into a vacuum system (02/22/16).
  • Understand how to define actuators and power subsystems.
    • President Watts said he will review this in our division meeting (02/20/16).
  • Research how to incorporate gyro, accelerometer, and/or magnetometer into inertial measurement unit in order to measure the angular rotation of our A-axis stepper motor (03/18/16).

 

Spring 2016 RoFi: Preliminary Design Documentation

/in /by

Christopher Andelin (Project Manager)

Mario Ramirez (Systems Engineer)

Qui Du (Manufacturing Engineer)

Andrew Laqui (Electronics and Controls Engineer)

Henry Ruff (Electronics and Controls Engineer)

 

Table of Contents

Program Objectives

The objective of Project RoFi’s is to design and implement a compact biped robot based on the original RoFi design by Jonathan Dowdall as described on the Project Biped website and quoted here.

ROFI is the fifth prototype from Project Biped.  It is a self-contained, bipedal robot that uses accelerometer feedback to balance. It has 12 DOF (degrees of freedom) and can walk around while avoiding obstacles using an ultrasonic range sensor. A small Android tablet in ROFI’s head provides the brains and an Arduino Mega provides the hardware interface.

All CSULB versions of RoFi add telerobotic control (including navigation) and monitoring of the robotic system by incorporating the Arxterra application and control panel.

The initial objective for the Spring 2016 project is to make operational the RoFi (Fifth Generation Robot), which was built during the Fall 2014 semester, as defined in the “BiPed Final Documentation.” The major change made in the Fall 2014 version of RoFi from the original, was to upgrade the head assembly to include a rotating mirror allowing the robot to view its surroundings.

Once operational this RoFi will run the course defined in the Mission Profile to the best of its abilities.  The Spring 2016 version of RoFi will identify and correct any design problems identified during this test.

The major change to be incorporated into the 2016 semester’s RoFi is the replacement of the overlarge head with a more compact design. Identified changes include:

  • Remove pan and tilt mirror assemble. While an Android or iPhone is still a requirement, vision may be provided by a commercially available periscope lens subassembly.
  • Replace the Arduino Mega with an Arduino with a much smaller form factor.
  • Replace the fuse and switch with more compact designs.
  • Replace the polyfuse array with an SMT equivalent design.
  • Replace all PCBs with custom designed SMT solutions.

Finally, the design will correct problems identified as part of the creativity exercise as documented in Creativity Section of the “Spring 2016 RoFi: Research Projects and Creative Exercise.” These include…

  • Bolts screwed into a plastic frame, which can come loose over time.
  • A running time of only 10 to 15 minutes.
  • Cables that are exposed and can easily come loose.
  • Moving parts that can cause harm.

Mission Profile

RoFi must complete an obstacle course on a figure 8 track. The course, shown in Figure 1, and located in VEC-501 was designed to validate RoFi’s design. The course will test RoFi’s ability to navigate in different directions and inclinations, over different surfaces, while keeping its balance.

track

Figure 1 The VEC-501 Course

As shown in Figure 2, the obstacle course will require RoFi to cross over a threshold, at approximately a 45° angle and a 2 cm height. From there RoFi must ascend an incline that is initially an 8° slope which then decreases to a 6° slope. Half way through the course RoFi must then start its descent down the incline towards the threshold again crossing over it at about a 45° angle proceeding towards its start position. Additionally, RoFi must acknowledge and avoid an object (i.e. a wall) and be able to traverse multiple types of surfaces which will include carpet, linoleum tile, and metal as defined here.  All of this must be completed while using the Arxterra™ application as per requirements.

slope

Figure 2 Course Details

*The above diagram was created in AUTOCAD™ 2014.

*Measurements were provided by the microSegway group, and confirmed by the microBiPed group as documented in the Micro BiPed Introduction.

Requirements

Program/Project

  1. Modifications to RoFi shall not exceed $320
  2. RoFi shall acknowledge and avoid objects within 3 feet
  3. RoFi shall traverse carpet, linoleum tile, and metal surfaces
  4. RoFi’s runtime shall be greater than 15 minutes
  5. RoFi shall cross over a threshold, at approximately a 45° angle and a height of 2 cm
  6. RoFi shall ascend an incline that is initially an 8° slope which then decreases to a 6° slope
  7. RoFi shall complete the figure 8 obstacle course through the Arxterra Application during finals week (Monday, May 9 – Saturday, May 14, 2016)
  8. Vision shall be provided through the onboard phone

Source: https://www.arxterra.com/fall-2015-microbiped-preliminary-design-documentaion/

 

Requirements (System/Subsystem)

Mario Ramirez (Systems Engineer)

  1. To satisfy requirement 1.5 and 1.6, RoFi shall use a gyroscope sensor to walk up an incline of up to 45 degrees.

a. A gyroscope sensor detects change in circular motion and orientation. Therefore a gyroscope sensor can be used for sensing: angular velocity, angle, and motion.  Such sensors are used in items such as cameras, aircrafts, and space shuttles.  This will therefore allow RoFi to adapt to inclines and accomplish requirement 1.7.

b. Our value of 45 degrees was obtained from the angle of the threshold within the obstacle course.

http://www5.epsondevice.com/en/information/technical_info/gyro/

  1. To satisfy requirement 1.2, RoFi shall use an ultrasonic sensor with a range of 3cm to 400cm.

a. An ultrasonic sensor emits sounds waves and are received back after reflecting off an object or surface. This type of sensor works on metal, nonmetal, clear, liquid, or solid materials.  The received waves can calculate the distance from an object using echolocation similar to that of a bat. The previous semester’s ultrasonic sensor has a range of 3-400 cm.  Other sensors have a range of 3-400cm. Our software will determine the range at which RoFi will avoid an obstacle.  This distance will be determined once the head design is complete and we know the height placement for the sensor. An ultrasonic sensor will allow RoFi to detect and avoid objects even in the dark within an optimal range.

b. The optimal distance for RoFi to begin his avoidance maneuver will be tested.

http://www.ab.com/en/epub/catalogs/12772/6543185/12041221/12041229/print.html

https://www.teachengineering.org/view_lesson.php?url=collection/umo_/lessons/umo_sensorswork/umo_sensorswork_lesson06.xml

http://www.seeedstudio.com/wiki/Ultra_Sonic_range_measurement_module#Introduction

 

  1. To satisfy requirement 1.3, RoFi shall have material with a coefficient of friction on the bottom of his feet.      

a. The material that RoFi will have on his feet will be based on our research of what material allows RoFi to walk on multiple surfaces, but still be able to move freely.

 

  1. To satisfy requirement 1.4, RoFi shall use two Glacier 2600mAh 2S 7.4V LiPo Receiver Batteries

a. More information is found here https://www.arxterra.com/spring-2016-rofi-battery-trade-off-study/

  1. To satisfy requirement 1.7, RoFi shall use a power class 2 Bluetooth module, which has a range of 10 meters between the module and cell phone.

a. Bluetooth operates in a band of 2.4 to 2.485GHz. A Bluetooth module will allow for communication between a cellphone and our Arduino.  From here we can use the ArxRobot app in order to control our Arduino which is ultimately controlling our robot.

https://learn.sparkfun.com/tutorials/bluetooth-basics/how-bluetooth-works

  1. To satisfy requirement 1.7, RoFi shall use servos that can supply a minimum torque of 288 kg*cm.      

a. To insure that RoFi can walk the torque stated above is needed to move the largest mass attached to our servos. To calculate this torque we used torque=r*F*sin(theta).  Where r is the distance and F is F=mass*gravity.

Link to the finalized torque report will be provided soon.

  1. To satisfy requirement 1.1, We shall:

a. Use 11 out of 12 servos from the previous group, one is broken and must be replaced.

b. Test sensors and use all operational components.

c. Re-use wires.

d. Allocate most budget resources to updating the Arduino and parts needed to implement our design on a smaller Arduino. These parts are referring to components such as servo drivers.

      8. To satisfy requirement 1.8, We shall be implementing a parascope that attaches to the onboard phone

a. TBD

 

Product Breakdown Structure

pbs

System Block Diagram

Adapted from,  https://www.arxterra.com/fall-2015-microbiped-system-block-diagram-update/

system block diagram

The sensors subsystem will be in charge of telling RoFi his next action.  When the gyroscope senses an incline/decline this will alert the Arduino which ultimately leads to the Actuators subsystem to adapt accordingly based on our code.  The same process will occur when the Ultrasonic sensor senses an object or a wall ahead of RoFi.  Bluetooth is considered a sensor because it collects inputs from a source, in this case an Android phone, then sends that data to the Arduino thus telling RoFi what to do based on our code.  The communication subsystem is connected to the sensors subsystem because through Bluetooth the Arduino will obtain information on the action it will take.  The Power subsystem consists of the battery which has been tested for our overall system and a regulator to insure the safety of the system and the user(s).  Our Actuator subsystem is our output, RoFi’s desired movement, based on our sensors and code

Interface Definitions

https://www.arduino.cc/en/Hacking/PinMapping2560

https://www.arxterra.com/project-documentation/

table1

table2

table3

arduino mega

Taken from, https://www.arxterra.com/project-documentation/

This Eagle schematic shows direct connections from the sensors and actuators to the Arduino Mega.

 

Mechanical Design

Qui Du (Manufacturing Engineer)

Objectives for this Design

The Android device is attached to RoFi’s head to control the Aduino Mega board. A phone with dimensions 124.6 X 61.3 X 8.94 is used for this project. As Manufacturing Engineer, I need to design phone brackets that will attach to the android phone on RoFi’s head. After doing research on this topic, I have ended up with the “RoFi- Next Generation Head- DAREL” designed  by Mike Pluma. I used the phone brackets prototype from this design to remodel brackets using SolidWorks that could fit with our android device dimensions.

SolidWorks 3D Modeling Design

The phone brackets attach to the back of the body base of RoFi. The screws go through the slots on the brackets and the holes in the body base. In this design, the bracket will support the phone in either verital or horizontal orientation. To achieve this goal, I design the width of  each bracket to have the dimensions of half the phone’s width.

Width dimension of bracket=(width dimension of phone)/2 = 61.3/2= 30.65mm

Brackets Dimension Analysis Model (Printed parts from RoFi Project)

Source: http://web.csulb.edu/~hill/ee400d/Project%20Folder/Robots%20and%20Drones/BiPed%20Robot/RoFi%20Project/

Bracket Dimension Model

SolidWorks Brackets Design

Step 1: SolidWorks model of right bracket:

Right Bracket design

Drawing modeling of right bracket:

Drawing_Right_Bracket

Step 2: SolidWorks model of left bracket:

left bracket design

Drawing Model of left bracket

Drawing_Left_Bracket

Step 3: SolidWorks model of the Android device

Phone’s dimensions: 124.6 x 61.3 x 8.94mm

Android Mobile figure

Step 4: Assembly modeling and exploded view

The high sides of the brackets support the phone in the vertical orientation

Exploded View_Vertical

Phone_Brackets_Vertical_Assembly

The high sides of the brackets support the phone in the horizontal orientation

Exploded View_Horizontal

Phone_Brackets_Horizontal_Assembly

 

Electronic System Design

Subsystem Descriptions

Henry Ruff (Electronics and Controls Engineer)

 

Servos:

The core part of ROFI utilizes 12 servos working together to create bipedal movement. Each of the servos will be controlled by appropriate code, to construct frame-by-frame animation of ROFI walking.

 

Gyroscope Testing:

In order to utilize the gyroscope for stabilization purposes, experiments will be conducted to read sample data from a force being applied, and then coding the servos to respond appropriately in order to correct ROFI’s center of balance, allowing him to recover from the force that was applied to him.

 

Ultrasonic Sensor:

The ultrasonic sensor will be appropriately tested to be able to have the servos respond in a way that allows for suitable avoidance of objects.

 

Power Consumption:

Applicable to all electronic aspects of the project, it is essential to the project to know the overall expected power consumption of ROFI. In this case, each component’s rated specifications can be used to calculate their power consumption, and altogether an estimate can be made for ROFI. Listed below are the maximum power consumption of each component, their datasheets, and the expected total.

As for the Arduino Mega in particular, the amount of current it draws is dependent on the amount of pins used, the code being run, and components of the Arduino board itself. Because of this, its power consumption will be measured once fully assembled.

table rev.2

 

Fritzing Diagram

Andrew Laqui (Electronics and Controls Engineer)

Fritzing Diagram:
The diagram shows a simple way of wiring the Arduino MEGA, Bluetooth communicator, accelerometer, and servos together using a breadboard and power supply. This is the beginning of how we will design our group’s PCB.

Fritzing Diagram

Fritzing Schematic:
The schematic is a more detailed depiction of how the parts will be wired together. The schematic shows on the Arduino MEGA which pins will be used. As seen in the schematic, all twelve PWM pins will be used for the twelve servos that are predicted to be used for RoFi.

Fritzing Schematic