Spring 2018: BiPed Preliminary Budget

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By: Miguel Gonzalez (Project Manager & Manufacturing)

Approved by: Miguel Garcia (Quality Assurance)

updated: 4/29/2018

Related Requirement

L1-10: Micro FOBO shall not exceed a cost of $250 to construct.

Objective

Project BiPed is one of this semesters robot production division in which a bipedal robot will be designed, engineered, and produced by the end of the semester. One of the most important tasks of any project is to evaluate and determine the cost of production of said products. In this post, we will be looking at the estimated cost of producing the BiPed robot. These costs will solely rely on physical component cost and any design and research development cost will not be mentioned in this post.

As part of the requirements stated by the customer, a budget was set for each project divisions. This is a loosely budget of $250 in which all material bought can be reimbursed in full. Any additional items and/or services that exceeded this budget will be covered by the team members working on the project. To help reduce costs, the customer has allowed access to his lab stock inventory of electronics, hardware, and materials. Borrowed items will be included in the budget table but the costs of the items will not be included in the total money spent.

Fig.1 Spring 2018 BiPed Budget Table

Budget Table (for access to links found on the table)

Summary

The above table shows the cost of components we have used and purchased as of April 18, 2018. The budget table above is divided into ten separate columns indicating important information about the used and purchased products. In the left column are the names of the parts and items used by the team to produce the biped robot. To the right of the parts column, is a link section that allows viewers to find the same parts we used for this project online. The table is also set up for invoice collection for any items that were purchased these invoices/receipts are linked on the second column to the right of the table. The budget table tries to incorporate all useful information that may be needed for future part purchases, replacement of parts, and for reimbursements.

Overall, we wanted to make sure not to spend any unnecessary money and to reuse as many electrical components and hardware as we could. It is important to note that some additions to the table will be made as the project continues and more items are needed. Multiple hours of reading past blogs as well as research were done to reduce unnecessary consumption of resources and to allocate as much possible reused parts from previous semester projects. Our total expenditures as of April 18, 2018, is a grand total of $226.54 which is under the customer’s project funding of $250.

References

  1. https://www.arxterra.com/wp-content/uploads/2018/04/Budget-Table.pdf

Spring 2018: Biped Mass Report

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By: Jeffery De La Cruz (Mission, Systems, and Test Engineer)

Verified By: Miguel Gonzalez (Project Manager)

Approved by: Miguel Garcia (Quality Assurance)

Fig.1 Mass Report

The total mass of the Micro FOBO is at around 351.5 grams. This mass consists of the following:

  • Part 0: Hip Bracket x1
  • Part 1: Foot x2
  • Part 2: Servo Band x4
  • Part 3: Servo Bracket x2
  • Part 4: Servo Wrap x2
  • Part 5: Bearing Frame x1
  • Part 6: Body Riser x1
  • Part 7: Electronics Frame x1
  • Part 8: Head Compartment x1
  • Micro Servos x8
  • Samsung ICR18650 x1
  • Arduino UNO x1
  • Servo Shield x1
  • Ultrasonic HC-SR04 x1

To view the excel file of the mass report, click here.

 

The mass of the Micro FOBO will change because the material used to print the parts of the Micro FOBO will change from regular PLA to carbon fiber PLA. The Micro FOBO will become just lighter but not by much. The mass of the Arduino UNO and servo shield is included at the moment but will be updated once the 3DoT Board of the Sparkfun Pro Micro 3.3V/8MHz is included. Also, the battery case was not included because the position of the battery is to be determined.

References

  1. https://drive.google.com/open?id=1d0iSAl9_i4ClQRSkrW_wMS650_uzvDZU

Spring 2018: Updated Prototype Fritzing Diagram

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By: Jorge Hernandez (Electronic & Controls Engineer)

Verified By: Miguel Gonzalez (Project Manager)

Approved by: Miguel Garcia (Quality Assurance)

Fig.1 Updated Prototype Fritzing Diagram

This is an updated Fritzing diagram, especially for Micro Fobo. A PCA9865 servo expander was used because we need to drive 8 micro servos and this expander breakout board lets us use up to 16 micro servos if needed. We only need 8 and that is why 8 headers are empty as they are not needed. A TCS9648A multiplexer board was used as we are using 2 UV’s and they will need different addresses If we want to gather information from them individually. This multiplexer board allows us to have 8 of the same sensor all with different addresses but we will only be using 2. We also have an external power source that will be connected directly to the Ultrasonic that is connected to the Pro Micro. The external power source is also connected to the servo expander and the micro servos will need much more than just 3.3V that is provided from the pro-Micro to run.

References

  1. https://www.arxterra.com/spring-2016-rofi-pcb-design-alternative-arduinos-and-custom-eagle-components/

Spring 2018: BiPed Planning and Schedule

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By: Miguel Gonzalez (Project Manager & Manufacture)

Approved by: Miguel Garcia (Quality Assurance)

updated: 4/21/2018

Objective

The objective of this post is to implement organization for the overall schedule of our BiPed project. This schedule is comprehensive and accounts for all tasks that should be completed by the displayed due dates. Using Project Libre, we can list the tasks needed to have a successful project. By using the Gantt chart feature we can see the tasks in a much more comprehensive chart that clearly demonstrates time frames and work periods. All tasks and due dates listed were imported from our class task matrix.

Overall Goal

Of course, like any project, our goal for BiPed robot is to finish every task on time while meeting our initial level one and level two requirements. To succeed, the following Gantt Chart was created with very precise timelines and due dates for procedural tasks that must be met to succeed in completing the BiPed robot on time. When creating the Gantt Chart, we notice three major tasks that are important to the success of the project. These tasks were the general project plan, finalization of the 3D model, and the final blog post. The deadlines for these tasks are March 15th, April 12, and May 8th in that order. Because the completion of these tasks is important we made sure to leave time after deadlines for adjustment and revisions. It is allowable to miss a deadline for tasks, but a penalty exists that increases as time passes. To prevent loss of points, additional precautions were put in place. As a group, we set the goal to complete these important tasks and blogs one class day in advance to confirm the completion of tasks within the timeframe.

 

Fig.1 Gantt Chart pt1

Fig.2 Gantt Chart pt2

Fig.3 Gantt Chart pt3

Burndown Chart

Fig.4 Burndown Chart

At the start of the semester, our team was quick and productive in submitting material and doing research for the project. Initially, the number of tasks was low and amount of time was high thus, we were more productive compared to the actual workload that was given. As the weeks passed our team fell behind as other classes also increased in workload. The increase of work, unfortunately, caused our group to fall behind on assignments that resulted in our group to work overtime during the spring break. This inrush of productivity allowed our team to regain a proper schedule by the end of our spring break.

Now that we are approaching the end of the semester we are tasked to meeting tough deadlines and yet again when looking at the breakdown chart we can see have more stuff to work on compared to the time that we have.  At this time our group has developed a mutual consensus that we need to increase our productivity and work together for the success of our robot.

Spring 2018: Micro FOBO Mechanical Designs

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By: Miguel Gonzalez (Project Manager & Manufacturing)

Approved by: Miguel Garcia (Quality Assurance)

Table of Contents

Notice

In this blog post, you will learn about initial mechanical designs for the Micro FOBO. We will discuss our thought process for each design component and relate it back to the customer’s requirements. Note that this the first post for the mechanical drawings of the miniaturized FOBO design created by Jonathan Dowdall. New advances in construction and design of the robot will be updated in a future post and linked at the bottom of this page. It is important to note the models shown in this post have yet to be physically tested. But plans to 3D print them have been made and the parts will be tested together. All results will be posted in a follow-up update blog post detailing our results of the models introduced here.

Introduction

The ROFI and FOBO bipeds can be considered as aging robots in which the designs have been used in many occasion for EE 400D projects. This can be particularly helpful if new students like ourselves would like to make such robots, considering resources for these models are plentiful on Arxterra.com. Unlike previous semesters our biped design will not encapsulate the same model but instead be a miniaturized version of those robots. Our group will particularly focus on the FOBO design by Jonathan Dowdall which is found on projectbiped.com. The miniaturized FOBO will be much smaller than the original approximately 60 percent its size and be controlled via micro servos (SG90S). We hope that in miniaturizing the design we can achieve a more efficient way of making the robot walk, turn, and avoid obstacles; all which are some design criteria for the maze.

Related Requirements

Level One Requirements

L1-3: Micro FOBO will have 2 legs.

L1-4: Micro FOBO will be a toy robot based on the design of the FOBO by Jonathan Dowdall.

L1-11: Micro FOBO shall be 60% or less of the overall size of Jonathan Dowdall’s FOBO

Level Two Requirements

L2-2: Micro FOBO dimensions will need to be small enough to fit in a 4in by 4in box for maze purposes.

L2-14: Micro FOBO shall measure within 4.5” x 3.25” x 7.25”.

Micro FOBO Design

For some clarification and for better understanding our design of the Micro FOBO, I have created a color-coded assembly of the robot with matching titles indicating the names of each component. Below I discuss the design of these components that make up the Micro FOBO.

 

Fig.1 Micro FOBO Colored Parts

As you can see from the image above, the Micro FOBO consist of 9 different parts: Servo Hip, Foot, Servo Band, Servo Bracket, Servo Wrap, Bearing Frame, Body Riser, Electronics Frame, and the Head. Note that Micro FOBO can be made up of multiple copies of the same part component and thus colored coded with the same color. For example, there are four servo bands in Micro FOBO which are shown in light green on the picture. Now that we know which parts make up the robot we can begin looking at the design of each part individually.

Part 0: Servo Hip

Fig.2 Servo Hip

The “Servo Hip” component of the Micro FOBO is responsible for attaching the two upper micro servos which are the hip servos. This bracket connects both servos (right and left legs) together to act as a hip bone that allows the robot to move its legs left to right. The connection to the servos is made via servo horns that are provided by the manufacturer. This part has two allocated trenches that match the dimensions of the servo horns allowing the servos to mount to the part. The horns are then screwed onto the servo hip using M2.5 screws that are 8mm in length.

Drawing File

Part 1: Foot

Fig.3 Foot

The “Foot” component is the same for both legs and is a simple shoe like design with wide pads on its sides. The extra material on the sides allows a greater amount of surface to touch the floor allowing the robot to balance easier. Currently, this part is in its simplified state as there is not much detail design put on it. This is because the team plans on mounting UV sensors onto the bottom of the foot where the hole is located. This would allow the sensor to be as close to the ground as possible to maintain an accurate reading. Once we receive the sensor additional design changes will be made to this part. Currently, the part allows the ankle servo, which is the servo closest to the ground, to be mounted onto one side of the foot though servo horn cutouts. The horn cutout is located on the inside wall of the part. The hole then allows an M2.5 X8 screw to secure the servo onto the foot piece.

Drawing File

Part 2: Servo Band

Fig. 4 Servo Band

There is a total of four “Servo Bands” located on the Micro FOBO. This part is responsible for grouping two micro servos together which forms a section of a leg. The two servos are pressure fitted into the square cutout and thus this part must be dimensionally precise to prevent servos to come loose. This piece had several revisions to satisfy the dimensional accuracy need to keep the servos secure. The servos were measured with a caliper and the thickness of the servos stickers even had to be considered when designing this piece. Due to leg movement constraints, only one servo can have extra material to be screwed onto the part.

Drawing File

Part 3: Servo Bracket

Fig.5 Servo Bracket

The ‘Servo Bracket” is a shorter version of part 0: servo hip and serves a similar purpose. This component mounts onto two servos that are located on the servo bands. This allows the second to the top servo to move the lower leg. This piece is located in the middle of the leg and connects the top and lower sections. This piece can be thought as the knee of the robot. Just like the other brackets, there are two cutout trenches that allow servo horns to be mounted and secured through a single screw. This piece can be varied in length to adjust the height of the robot and adjust the walking stride of the robot itself.

Drawing File

Part 4: Servo Wrap

Fig.6 Servo Wrap

The “Servo Wrap” is a small piece that attaches the back of the hip servo (top leg servo) to be mounted onto part 5: Bearing Frame. It is connected via an M2 screw that is 18mm in length. The screw goes through the servo, through the servo band, and screws into this piece. A hole on the left side of the wall was added to allow the servo wires to feed through and connect back to the electronics. Notice there is a hexagon trench located near the middle of the part. This trench allows an M3 nut to be placed in that location and lets a screw to secure Part 4 with Part 5. Another key design feature is the chamfer cutout located on the backside of the part. This permits higher degrees of movement from the hip servos by at least 45 degrees more.

Drawing File

Part 5: Bearing Frame

Fig.7 Bearing Frame

The “Bearing Frame” is a mirror-like component to part 0 as both pieces work together to provide the connection of legs to body. One of the key differences is that this piece contains two large circular trenches in which a bearing can fit onto. Using a 10mm circular bearing we place it on the part to provide free angular movement to the left and right sides of the pieces. Once the bearings are fitted inside, we can use M3X14 bolts to attach the servo wrap pieces to the left and right side of the Bearing Frame. Since the legs servos are already attached to the servo wrap we effectively attached the two legs to the body of the robot.

Drawing File

Part 6: Body Riser

Fig.8 Body Riser

Micro FOBO mainly consists of a head and two legs but this part, body riser, can be considered the body of the robot. This component connects the two attached legs with the head. There are two fork-like structures located at the top of the piece that allows part 0 and part 5 to fit in snugly effectively connecting the two legs to this piece. Part 0 and part 6 are secured through a couple of M3 screws with an approximate length of 16 mm. The back side of this component is flat and has two holes for connecting to part 7 which is the electronics frame. The body riser can be increased in height allowing the robot’s head to be located higher above the legs. We can experiment with changing the height to allow shifting the robot’s center of mass higher or lower as needed.

Drawing File

Part 7: Electronics Frame

Fig.9 Electronics Frame

The Electronics Frame is a thin component that is responsible for connecting the PCB to the body riser. The PCB will contain four mounting holes which will allow the board to connect to this part. Note that the part contains extruded cubes that correspond to the location of the PCB hole mounts. These extruded cubes also have a hole cut out to fit M3 screws that secure the board in place. Finally, the part can be secured to the head via similar M3 screws on the side of the part and head

Drawing File

Part 8: Head

Fig.10 Head

One of the first challenges in creating a miniature FOBO we observed was that our robot would need to support large amounts of electronic components that used to be on the regular size FOBO. These electronics would need to be smaller in size or our head design would need to optimize to fit all the electronics. Our first design was based on the prediction that the new electronics would have a smaller footprint and thus the head of the Micro FOBO is much smaller. The exact dimensions can be found on the link below. Once the size of the head was set I began to look at some redesigns that I can implement to change the look and functionality of the robot’s head. That is when I stumbled on an image of a tin toy robot from the 1950s.

Fig.11 1950’s Tin Toy

As you can see from the image above this robot has a similar head as the FOBO which gave me the idea of emulating the design of the face. The ultrasonic sensor will take place as the robot’s eyes and the mouth and nose features would simply be aesthetics. Another thing that I noticed was that the tin toy contained antennas on the left and right side of the head. One of the redesigns I wanted to incorporate since the beginning was adding turn signals to the robot and the antennas can certainly be used for that. My idea is to have small 5mm red LED’s as the tip of the antennas that would blink indicating when the robot will turn and in what direction. Finally, we see that there is a small red light on top of the robot that can be designed to indicate on/off status of the robot.

Fig.12 Mechanical Design Improvements

Drawing File        Tin Robot Toy

 

Spring 2018: BiPed Work Breakdown Structure

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By: Miguel Gonzalez (Project Manager & Manufacturing)

Approved by: Miguel Garcia (Quality Assurance)

Table of Contents

Work Breakdown Structure

For project BiPed, the group consisted of three members fulfilling the roles of Project Manager, E&C, MST, and Manufacturing Engineer. Since the group consisted of fewer members than the positions to fill the manufacturing role of the team was given to the Project Manager.

The diagram below shows the workload of the project and how it is distributed among the team. It is based on the job descriptions and shows major tasks that each person is responsible for. We will be taking a look at each team members role more closely to better understand the structure of the team and its workload.

Fig.1 BiPed Work Breakdown Structure

Miguel Gonzalez (Project Manager)

Fig.2 PM and Manufacturing Engineer Tasks (Blue)

At the top of the WBS in blue, we have the project manager section. Note that in our case the project manager is also the manufacturing engineer and thus the tasks for both roles are given to the same person. The second blue icon shows the tasks specific to the project manager which has the project manager responsible for the following tasks:

  • Creating and managing schedule
  • Creating a budget list
  • Creating the preliminary report
  • Creating the final blog post
  • Creating project video
  • Define Work Breakdown Schedule

The manufacturing tasks given to the project manager are listed to the right side of the WBS also in blue. These tasks are broken down into three sections Mechanical Design, 3D Modeling, and Assembly. These sections were created based on which tasks are needed to be done before moving on to the next section. For example, Mechanical Design is a prerequisite for 3D Modeling and Assemble thus it is located on top of the other tasks.

Jeffery De La Cruz (MST)

Fig.3 MST Tasks (Red)

Moving on to the left side of the WBS (in red), we have all the tasks assigned to the MST engineer. Once again, these tasks are divided up into three sections System Designs, Software, and System Tests. The system designs include tasks that have a focus on research and trade studies that will end up helping with the software development and system test. Once those tasks are done the MST engineer can proceed with implementing the software with the Arxterra control panel and onto an android application. The final tasks for the MST engineer focus on verifying and testing all sections of the robot to see if they are operational.

Jorge Hernandez (E&C)

Fig.4 E&C Tasks (Green)

The final branch in the WBS applies to the E&C engineer and his tasks needed for a successful project. The E&C has the greatest responsibility for the success of the robot becoming operational. His roles are divided into 4 categories Electronics Design, Experiments, Microcontroller, and Control. These categories cover a wide range of taks that need to be realized to proceed with the overall goal of the Biped project which is stated in our preliminary design blog post and here.

Spring 2018: Biped Fabrication Methods (Trade-off Study)

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By: Miguel Gonzalez (Project Manager & Manufacturing)

Approved by: Miguel Garcia (Quality Assurance)

Table of Contents

Related Requirements

L1-3: Micro FOBO will have 2 legs.

L1-4: Micro FOBO will be a toy robot based on the design of the FOBO by Jonathan Dowdall.

L1-18: Micro FOBO shall be able to traverse cloth, paper, and linoleum materials.

Introduction

When thinking about manufacturing our robot we looked at the many fabrication methods available that we could use to create the BiPed. Of course, the list of ways we can manufacture our robot can be endless, but we made sure to focus our research to limit this list. Our goal for this study is to list the most feasible methods of fabricating our robot and compare the pros and cons of each method. The top three most feasible fabrication methods we could implement on our robot was sheet metal folding, laser cutting, and 3D printing. This blog study will look at each method mentioned to see the benefits and disadvantages of incorporating them into our design. Below you can find our study and the results we arrived when conducting a few tests.

Sheet Metal Folding Method

Fig.1 Sheet metal folding example

The first fabrication method we looked at was sheet metal folding which is a process of getting thin metal sheets and cutting them into specific shapes that would be folded to produce a three-dimensional shape. This shape can be a servo mount, 3DoT casing, robot feet, and so much more. Sheet metal folding is cheap and is a good way to produce sturdy parts rapidly without much effort. One of the drawbacks of this method is that complicated designs are almost impossible to produce. Accurately measured pieces are hard to produce and making exact copies of parts that share the exact dimensions are nearly impossible to make using this method. These drawbacks are too big to ignore especially when we plan on creating a robot that requires precision measurements and complicated design.

Laser Cutting Wood

Fig.2 Laser cutting example

The next fabrication method we consider was laser cutting. Laser cutting is a very niche fabrication method for hobbyists but has been gaining traction in the recent years. With the laser cutting method, you can use various materials for your builds such as sheet metal, plastics, and even wood. This method of fabrication utilizes the precision of a powerful laser to cut material into a predefined shape. This means that you can achieve very accurate and precise cuts. Laser cutting, in general, is very versatile but our team realized that we lacked knowledge on how to use a laser cutter. It was also clear that laser cutting would only be used for a section of our robot design and can’t make complicated three-dimensional shapes that extend well above the laser’s cutting threshold. This takes us to the third fabrication method mentioned below.

3D Printing

Fig.3 3D Printing Diagram

Out of all the fabrication methods described in this blog post, 3D Printing was the only method of creating stuff that has been used by a team member. 3D Printing is a fabrication process of creating a three-dimensional object by adding small amounts of material upon itself until the desired shape/object is obtained. There are multiple ways a 3D printer can produce a design, but we focused on an additive manufacturing process called Fused Filament Fabrication (FFF). This is the most common consumer grade process that is readily available.

With 3D printing, we can model our robot’s chassis designs and print them out at the same dimensions specified in the CAD model. This would allow us to expedite the design and manufacturing process in our project. 3D printing also allows us to create precise measurements and make exact copies of parts while maintaining constant measurement accuracy at each copy. With FFF 3D printing we are limited to using only plastic materials but fortunately, we can choose from various plastics that have different properties. In a later blog post, we will be looking at the different materials available for FFF 3D printing and looking at their properties.

Conclusion

After considering all three methods of fabrication we decided that we should use 3D printing to create all the designs in our robot. 3D printing’s only drawback was that it can only produce stuff in plastics, but our team has concluded that plastic has enough robustness to make our robot function and complete the maze. Lastly, our class has been informed that multiple 3D printers are available in house to produce our robot parts and thus this method of fabrication is also the most available for us.

Sources

  1. https://www.tractorsupply.com/know-how_hardware-tools_metalworking_working-with-sheet-metal-safety-tools-and-sheetmetal-projects
  2. https://www.wikihow.com/Use-a-Laser-Cutter
  3. https://library.ucalgary.ca/makerspace_equipment/3D_printing
  4. https://www.3diy.org/