Spring 2017 Final Blog Post – Pick and Place

Belinda Vivas (Project Manager)

Tyler Jones (Manufacturing)

Kevin Ruelas (Electronics)

By: Chastin Realubit (MST)

Executive Summary

Program Objective

By: Belinda Vivas (Project Manager)

The objective of the Second Generation of the Pick and Place is to:

❖Build up from the First Generation of the Pick and Place machine and create an user friendly design.

❖Create a user friendly manual:

  • Softwares
  • Step by Step
  • Wiring
  • Troubleshooting

❖It shall be built in stages.

❖Make the Pick and Place consistent with the manufacturer of only a few boards per semester.

Mission Profile

By: Belinda Vivas

The mission plan for the Second Generation Pick and Place is to place all components used for the 3Dot Board 4.54 faster than a person. Manufacturing time of a person is 4 hours, so anything less than that is acceptable, with 1 hour being the target time.

The overall goal of this project is to have a working Pick and Place machine for future EE400D students to build their custom PCB. The 3Dot Board that will be constructed is more difficult than any PCB students will make, therefore, this machine can theoretically make any board future students plan to do.

Because this machine is supposed to be used by students, we will include manuals (written and video) so that future generations can operate this machine with ease. We will conduct experiments using Electrical Engineering students to see if they can operate the machine using only the given manuals.

The overall summary for the Mission Profile is:

❖To create a 3-Dot 4_54 PC Board.

❖Ensure precision and calibration through the addition of a camera system (Edge Detection).

❖Create a CSV file to implement a better interface between the user and the machine.

❖Multiple feeder assemblies

❖Incorporate better materials

❖Tape feeder for the following component parts:

  • 0402
  • 0603
  • 0805

Design

Project Features

By: Belinda Vivas (Project Manager)

Figure 1 – Detailed Design of Generation 2

Electronics:

❖Camera System

  • Edge Detection

❖Two Arduinos System

  • Independent from each other

❖Vacuum System

❖Servos System

❖Power Emergency Switch

  • Relay to cut power on the motors

Manufacturing:

❖Higher legs with rubber on the base to provide better stability due that more weight is being added causing for higher vibration.

❖Higher amount of component feeders.

❖IC Chip component holder

❖Power Switch

❖Camera

❖Component Cabinet

❖Electronics Cabinet

❖Tape waste bin

System Design

By: Chastin Realubit (MST)

Figure 2 – System Block Diagram

Testing

Solenoid and Vacuum Test

By: Tyler Jones (Manufacturing)

The vacuum by itself was powerful enough to carry the Atmega chip but experiments show that we need a bigger nozzle to increase airflow.

Figure 3 – Solenoid Circuit

Blog Post: http://www.arxterra.com/pick-and-place-solenoid-valve-design-and-control-2/

Z-Axis Test

By: Chastin Realubit (MST)

Z-Axis Motor: We did an experiment to see the load that the Z-Axis can handle and we found that it will still carry up to 2000 g. This experiment was done so that we can see if the motor can still move up and down even with more load. This was needed because we are adding a camera on the Z-Axis and we needed the system to still function with extra weight.

Figure 4 – Nozzle System

Blog Post: http://www.arxterra.com/pick-and-place-z-axis-and-nozzle-test/

Rubber Vibration Damping Test

By: Tyler Jones (Manufacturing)

-The machine has a basic feature of rubber shoes for legs of the platform stand.

-This will aid in damping vibrational disturbances.

-A 4” x 4” x 1” block of butyl rubber shaped using a bandsaw and miter saw.

-The block was fitted to form shoes that fit over the legs of the machine.

-The blocks have been tested on one leg for stability.

-The use of a milling router machine should be used

Additional Testing

Emergency Power Switch: http://www.arxterra.com/pick-and-place-emergency-power-switch/

By: Tyler Jones (Manufacturing)

3Dot IC Tray:http://www.arxterra.com/pick-and-place-3dot-ic-tray/

By: Tyler Jones (Manufacturing)

12 Servo Mount & Tape Feeder System:http://www.arxterra.com/pick-and-place-12-servo-mount-tape-feeder-system/

By: Tyler Jones (Manufacturing) and Belinda Vivas (Project Manager)

Camera Test: http://www.arxterra.com/pick-and-place-camera-test/

By: Kevin Ruelas (Electronics)

Solenoid Valve Design and Control:

By: Tyler Jones (Manufacturing) and Kevin Ruelas (Electronics)

Servo Driver: http://www.arxterra.com/pick-and-place-servo-driver/

By: Kevin Ruelas (Electronics)

Camera System: http://www.arxterra.com/pick-and-place-trade-off-study-camera-system/

By: Kevin Ruelas (Electronics)

User Interface

GRemote

By: Kevin Ruelas (Electronics)

Though the user can type commands manually in the GRemote, once the machine is running and calibrated, use command G28 to set the origin then send the CNC file and wait for the machine to do the rest.

Figure 7 – GRemote controller

Figure 8 – GCode Commands

Figure 9 – Arduino 1 Interface Definitions

Figure 10 – Eagle CAD to Pick and Place

Camera Fritzing Diagram

By: Kevin Ruelas (Electronics)

Figure 11 – Camera Fritzing Diagram

Recalibration of Origin

By: Kevin Ruelas (Electronics)

Since the 1st Gen. already defined the origin, the edge detection of a “target” will be used to calibrate this location and prompt the user to make this correction via GRemote.

Electronics Design

By: Kevin Ruelas (Electronics)

The overall Pick and Place was composed of various subsystems which were all ran by a common code. The motors, the nozzle, calibration, camera, LCD display, servo driver, and solenoid.

Figure 12 – High Level Software

Blog Post: https://drive.google.com/open?id=0B9iWYCBTJWEEeEFxc1pjU0ZFTjQ

SolidWorks Model

By: Tyler Jones (Manufacturing)

Figure 13 – Side View of SolidWork Design

Figure 14 – SolidWorks Top View Design

Verification and Validation Test

By: Chastin Realubit (MST)

The purpose of this section is to provide a comprehensive Verification and Validation (V&V) Test Plan of the Spring 2017 Pick and Place including the Project ConOps/Mission, Test Methodology, Verification and Validation Matricies, Test Cases, and Exit Criteria.

https://drive.google.com/open?id=0B9iWYCBTJWEEU05NMy1SMUs2ajQ

Resource Allocations

Power Allocation

By: Chastin Realubit (MST)

Components Expected Current Draw (A) Uncertainty (%) Margin (±A) Measured Current Draw(A)
Stepper Motor (X-Axis) 1.35 5% .0675 .44
Stepper Motor (Y-Axis) 1.35 5% .0675 .44
Stepper Motor (Z-Axis) 1.35 5% .0675 2.83
Stepper Motor (A-Axis) 1.35 5% .0675 .44
Detection Camera .75 5% .0375 TBA
Solenoid Valve .40 5% .02 .42
Display Screen .75 5% .0375 TBA
Servo fs90r (12) .2 5% .01 .21
Project Allocation 6 A (Calculated knowing that we will be using two Arduinos with separate power supplies)
Total Expected Current 3.45 A (The motors and servos will not run simultaneously)
Total Margin .375 A
Contingency 2.175 A

 

Mass Allocation

By: Chastin Realubit (MST)

Vacuum System Components Preliminary Mass (g) Uncertainty (%) Margin (±g) Expected Mass (g) Actual Mass (g)
Stepper Motor (A-Axis) 245.00 5% 12.25 245.00 247
Stepper Motor (Z-Axis) 245.00 5% 12.25 245.00 246
Vacuum Nozzle 2 5% .1 2 TBA
Z-Axis Actuator 292.00 5% 14.6 300 244.12
Detection Camera 3 5% .15 3 TBA
Project Allocation .Preliminary allocation is 2000g
Total Expected Mass 795 g
Total Margin 39.35 g
Total Actual Mass TBA
Contingency  1165.65 g

Cost Report

By: Belinda Vivas (Project Manager)

For the Second Generation of the Pick and Place, our allotted project budget was of $500, in which a total of $469.04 was spent; it was divided as follow:

Receipt Vendor                Item            Unit Quantity Total Cost (Including Shipping) Purchased By
1 Makeblock RJ25 Adapter $4.98 1 $15.65 Kevin Ruelas
RJ25 cable-20cm (4-pack) 1
2 Amazon 12 Bit PWM Servo Driver $11.99 1 $11.99 Kevin Ruelas
3 Amazon Blue Backlight LCD Module $7.99 1 $7.99 Kevin Ruelas
4 Amazon 3-Pin Extension Lead Wire $6.99 1 $6.99 Kevin Ruelas
5 Amazon Arduino Power Supply Adapter $6.29 1 $6.29 Kevin Ruelas
6 Amazon 120 pcs Dupont Wire $8.86 1 $8.86 Kevin Ruelas
7 This item was removed. Arduino Uno will not be needed for the project anymore and the student requested to keep the board.
8 AdaFruit MicroSD Card $7.50 1 $52.56 Kevin Ruelas
JPEG Camera $35.95 1
9 Pololu Rotation Servo $4.95 9 $49.50 Chastin Realubit
10 GearBest LCD Display Screen $4.53 1 $17.18 Chastin Realubit
11 Amazon PWM Servo Driver $11.99 1 $15.98 Chastin Realubit
12 Ebay Rubber Bench Block $7.48 1 $7.48 Tyler Jones
13 Sewvac LTD Bobbins for Servos $3.29 1 $3.29 Tyler Jones
14 RadioShack Mosfet IRF 510 $1.78 1 $1.78 Tyler Jones
15 ACE Hardware Nuts & Bolts $5.40 1 $5.93 Tyler Jones
16 The Home Depot Wood $29.98 1 $29.98 Tyler Jones
17 The Home Depot Aluminum Plates & Epoxy $35.68 1 $38.45 Tyler Jones
18 MicroCenter 3D Printer Filament $14.99 1 $16.15 Tyler Jones
19 The Home Depot Screws $18.49 1 $18.49 Tyler Jones
20 The Home Depot Plastic Sheet $140.06 1 $140.06 Tyler Jones
21 ACE Hardware Screws $14.44 1 $14.44 Tyler Jones
Total: $469.04  
Name of Individual Position Total Amount Reimbursed
Kevin Ruelas Electronics $110.33
Chastin Realubit MST $82.66
Tyler Jones Manufacturing $276.05
Total** $469.04

Updated Schedule

Top Level Schedule

By: Belinda Vivas (Project Manager)

 

Sub System Schedule

By: Belinda Vivas (Project Manager)

Concluding Thoughts

By: Belinda Vivas (Project Manager) and Tyler Jones (Manufacturing)

We were able to incorporate more extensive and higher technology subsystems into the Second Generation of the Pick and Place; by implementing a more user friendlier systems and introducing a camera system, LCD Display system, redesign of the nozzle, better calibration system, higher servo driver system, and an overall new manufacturing design.

The pick and place was successful in picking and placing parts onto the 3DoT board. The machine when calibrated can place parts into the respective locations where they can be soldered using the IR reflow machine. It is important however to note that the pick and place machine can be improved in the following areas. Its mechanical, and electronic design can be updated with simple solutions that require more time. They are discussed below.

The pick and place mechanical design can be improved in a noticeable and easily recognizable ways with more time for development. The first is the belt system.

1) The belt system does work well, and the X and Y stepper motors move to positions accurately, sometimes during design of the machine the tensioner plates that hold the 3 belts into place were loosened. This is so that parts in the machine can be easily worked on. Therefore it is important to make sure that belts are tight, as well as lubricated. Loose belts cause the machine to make a noticeable sound that is not as fluid as when they are tight. The best solution would be to incorporate threaded drives instead of belts, however this is more costly.

 

2) The pick and place uses a 3DoT board that was 3D printed with more than 6 iterations. This was due to numerous errors in the printing temperature, malfunction, and design limitations. There is a table that corresponds to part sizes and dimensions and adjustments made to account for error of the 3D print. It is found here, 3DoT IC Tray. A decent 3D printer and filament must be used in order to get the precise dimensions necessary. An alternative solution would be to cut a small rectangular piece of plastic that is about 0.5-0.75 inches thick, and have it precisely laser cut. The laser cutter used in the design center was not accessible in this generation later on in the project timeline.
3) The Z-axis is supported by two aluminium slider rods. These slider rods must be spaced as far apart as possible so that the heavier Z-Axis can have a wider more stable base and center of gravity. This design was used in the pick and place and must be incorporated if further design iterations will be made. The camera is mounted on a bracket that allows makes it so that the Z-Axis only can be bolted to two of the aluminium sliders. This must be made able to be bolted into all four of the sliders. It is shown below

4) The pick and place currently uses a locked position origin. This is so that the the machine can be turned off and moved back to the locked position manually. From here the pick and place machine can be moved to the function “L” bracket origin. It would be a much safer design if limit switch can be placed on the X and Y axis so that if the user were to accidentally enter the wrong code in the machine the motors would not grind. This can be accomplished by using the current limit switches and adding the limit switch code to the stepper motor.ino Arduino code. The limit switch acts as an electromechanical disconnect that simply switches off the stepper motors when the machine makes contact with the switches. An image of the switch is shown below.

5) The electronic design can be further enhanced if the 12 channel servo driver can be made to separate the digital power source which carries Arduino logic level signals of +3.7V and +5.0V, and the analog power source which carries +12V signals. The connection is made through the Me Uno RJ25 board. This connects an an RJ 25 communications signal with a 12 V analog signal.
6) The edge detection camera code was functional and the code calculated the position of the origin by comparing picture taken by the camera, and comparing the pixel lengths. The edge detection however was off by about 0.3 which is about 1mm in actual length. In order to improve the accuracy of the machine a higher resolution camera must be used.

Project Resources

Video – https://www.youtube.com/watch?v=2Cn5abf5Arw

Preliminary Design Document – http://www.arxterra.com/pick-and-place-preliminary-design-document/

Preliminary Project Plan – http://www.arxterra.com/pick-and-place-preliminary-project-plan/

PDR: https://drive.google.com/open?id=0B9iWYCBTJWEES1g1emo3NklpTmc

CDR: https://drive.google.com/open?id=1tGSSGGry0n6I4EDJ9IYzM1PXZUMOc_jJTCyYj9YSV1E

Blog Posts: https://drive.google.com/open?id=0B0hJ_mPvve6CRVpqOU1mdUN2aFk

Code Files: https://drive.google.com/open?id=0B0hJ_mPvve6CY0t5SjNuWk1OOEk

3Dot BOM: https://drive.google.com/open?id=1rC5BPWV3KqwXsGQ3CgFeVNoKTumOvdZjCftwd7t0eEU

Servos BOM: https://drive.google.com/open?id=0B7gruONfGRYcUExJeVBxMzNYblU

GCode Commands: https://drive.google.com/open?id=1CKODeCrm8FpmgrmSp363mjAMPNYaCCe5904dLSit4cs

3Dot 3D print File: https://drive.google.com/open?id=0B0hJ_mPvve6CNXVTQVNyVGxCT3c

3Dot Board: https://drive.google.com/open?id=0B0hJ_mPvve6CN25OSU01aEcwWlE

https://drive.google.com/open?id=0B0hJ_mPvve6CN2dIZHZXTzAtSWs

Ace Converter: https://drive.google.com/open?id=0B0hJ_mPvve6CTlI1NzNHX1BTLTQ

Arduino: https://drive.google.com/open?id=0B0hJ_mPvve6Ca1BpM3FGNDYzWVE

GCode: https://drive.google.com/open?id=0B0hJ_mPvve6CM2pNZ2hCWl9ZMXc

Me Uno Shield: https://drive.google.com/open?id=0B0hJ_mPvve6CUmtDcEN5LUxQSjg

Meeting Minutes: https://drive.google.com/open?id=0B0hJ_mPvve6CNXRhRFd5RThkR1k

Research: https://drive.google.com/open?id=0B0hJ_mPvve6CeS1tQmFRQ3hqQ3c

SolidWorks Files: https://drive.google.com/open?id=0B0hJ_mPvve6CaFVoR1RaRl93bkE

XY-Plotter: https://drive.google.com/open?id=0B0hJ_mPvve6CckVuWkJvOU53eEE

All Files: https://drive.google.com/open?id=0B0hJ_mPvve6CNXVTQVNyVGxCT3c

Instructional Manual: https://drive.google.com/open?id=1eXx-_8FduTJi8nRR356R3nj0DHnTqq50er3VYreTGXA

Project Libre Schedule: https://drive.google.com/open?id=0B9iWYCBTJWEET2pLMHVJVVd2am8

Verification and Validation: https://drive.google.com/open?id=0B9iWYCBTJWEEU05NMy1SMUs2ajQ

 

 

 

Pick and Place – Emergency Power Switch

By: Tyler Jones (Manufacturing)

In order for the pick and place machine to have a safe and orderly operation the pick and place needs to incorporate an emergency switch. This should be obviously labeled and easily accessible to the user. If something were to occur as the machine is operating it might take too long to disconnect the microcontroller located in the electronics housing. A large black button clearly labeled “STOP” was added to the exterior of the pick and place. The dimensions of the switch are included below in Figure 1.

Figure 1

 

There are two major power sources that are used in the pick and place machine. The first is a AC to DC power supply that connects the machine to an AC wall or power strip receptacle. Once converted to DC power, bundle of 2 wires feeds the Me Uno Arduino Uno shield. This then powers up both the arduino and shield on top of the arduino. All devices are run from power on the arduino or solenoid switch board circuit. For more information on how to connect the power supply and run the machine please read the instruction manual, or visit the INSTRUCTION MANUAL FOR PICK AND PLACE OPERATION. The other source of power that feeds the machine is the USB connection of +5V from the user’s computer to the pick and place. In testing the pick and place while operating it was found that the +5V is able to still have the code run for the pick and place. It does not however allow the motors, solenoid, or servo motors to run if the +12V power supply is disconnected.

Now by implementing a switch on the +12V line after the AC power has been rectified and converted, the user now has a way to easily stop all motion of the machine. The switch a black colored DPST (Double Pole Single Throw) switch. The switch is wired by splicing the power cord of the DC power supply at the DC end, and routing the power to the switch. In the “OFF” state the switch is open and nothing will run on the machine. In the “ON” state the power will connect to the Me Uno Shield and the machine will run. The Double Pole Switch allows 2 circuits to connect to the switch and the single throw controls the 2 circuits simultaneously. The second circuit is for the other arduino and second power supply if used. A simple diagram on the setup of a DPST switch is shown below in Figure 2

Figure 2

Pick and Place – 3DoT IC Tray

By: Tyler Jones (Manufacturing)

The pick and place needs to have a way that it can easily access all the integrated circuits, and components that cannot fit in SMT part reels. This means that an IC tray must be created to house all the components for the nozzle to pick up. The IC tray must also be very accurate in dimension that way there is no room for error for the nozzle to pick and place the part in the center of the part. The IC tray must also stand up off the picking surface and be able to to have small wells, or housings were the parts can fit into. The IC tray is shown below in Figure 1 It shows the basic dimensions of the overall build of the IC tray.

                                                    Figure 1

The 3DoT tray contains 22 unique part wells, as well as 6 copies. The copies of the wells exist on the tray because there are sometimes multiple of the same components necessary to complete the 3DoT board. The 3DoT board also contains components that need to be flipped or oriented at 45,90, or 180 degrees from the well. The A axis stepper motor accomplishes the task of flipping the component while it is already on the nozzle. This is done by programming the A axis stepper motor to turn using the GCODE commands. The A axis stepper motor is the axis that handles rotation of the parts, it also is connected to the nozzle and vacuum pump tubing. For further information on how to control the A axis stepper motor, or the design of the motors please refer to INSTRUCTION MANUAL FOR PICK AND PLACE OPERATION blog post, or the CALIBRATION blog post.

There was a problem in creating the wells of the IC tray. The first issue was that the Lulzbot TAZ 5 3D printer has an error of printing thickness of about 0.1-0.2mm. This means that after taking into account all the sizes of components an oversizing of about + 0.1 -0.4mm needs to be used in order to have the wells a little bigger than the part. Every part that goes onto the 3DoT tray was measured using calipers, and also cross-referenced with the datasheets from the manufactures. The following tables below in Table 1 Table 2 shows the size, part, number, description, dimension, error margin calculation, and other information for each part. The table is contained in the INSTRUCTION MANUAL FOR PICK AND PLACE OPERATION in order to aid the user in knowing where to place the components into the IC tray.

                                                                                                Table 1

                                                                                                 Table 2

The positions outlined in column 1 of Table 1 correspond to the positions used on the 3DoT board. They are organized from left to right and top to bottom, with the number of the part corresponding to the same number on the IC tray itself.

The 3DoT IC tray was designed so that the centerline of each part is consistent. This allows for much easier programming and calibration as the X coordinate does not move when the G CODE is running. Similarly, the height of the tray does not change which allows for the Z coordinate of the pick and place to not change. This also makes the machine much more time efficient. For information on troubleshooting the code corresponding to the 3DoT tray or how to calibrate the machine, please see the CALIBRATION blog post.

 

 

Pick and Place – SOLENOID VALVE DESIGN AND CONTROL

By: Tyler Jones (Manufacturing) and Kevin Ruelas (Electronics)

                                                                            Figure 1 

                                                                       Figure 2

The above Figure 1 and Figure 2 schematics show the solenoid circuit simulated in LTSpice. The circuit on the left shows that when the arduino pin is set to high the circuit turns on allowing the current to flow through drain and source to the solenoid valve. The circuit on the right shows that when the arduino is set to low, there is no current flowing through the drain and source to the solenoid.

This creates an electronically controlled switch, and can be programmed to turn the pump on when picking a part, and off when placing a part. This is vital to the pick and place control system because it needs to be able to switch on using power from the Me Adapter board of +5V, to control a larger voltage of +11.7V from the Me Uno header pins. The IRF 530 MOSFET switches the gate voltage of +4.7V to the source drain voltage of +11.7V This voltage can is now large enough to drive a current to the solenoid and turn it on and off.n The diode is placed from power across to the solenoid as a flyback diode. This means that the cathode points toward the positive power rail. The diode is a 1N4001 1 amp diode. The sole purpose of the flyback diode is to prevent the unwanted voltage spike that can be created in the inductive solenoid coil. The IRF 530 MOSFET was chosen based on the datasheet values that it can handle lower logic level voltages to turn on, and can channel about 20V across the source drain channel. This is more than enough to handle our 12V source drain voltage The +4.7V control voltage from the arduino is programmed to correspond to the following values.

CODE SENT $9 (GCODE) $10 (GCODE)
ARDUINO PIN +4.7V (HIGH) +0V (LOW)
IRF 530 MOSFET ON OFF
SOLENOID ON OFF
SUCTION PUMP ON OFF
ACTION PICK PLACE

 The solenoid was tested using an ammeter in series with the Drain of the MOSFET and wire of the solenoid. The current draw shown in Figure 3 through the MOSFET into the load was about 410mA. The turn on current needed to excite the coil in the solenoid was found to be about 310mA. This means that the solenoids resistance value can be modeled most accurately as an inductive coil load in series with a resistive load. The total resistance of the solenoid based on current draw was an operating range of about 24-35 ohms. The circuit works as designed and tested.

                                                                Figure 3

The tested circuit shown above was translated into a custom soldered PCB, in order to have the wires and components secured to a fixed location within the electronics housing. The PCB board will be mounted on standoffs inside the electronics housing.

Pick and Place – 12 Servo Mount & Tape Feeder System

By: Tyler Jones (Manufacturing) and Belinda Vivas (Project Manager)

 

Figure 1

In order for the pick and place machine to be able to complete one board, it must be able to pick and place many different devices for a whole board. It must be able to pick and place capacitors, and resistors of varying sizes 0402, 0603, and larger. For the purpose of the 3DoT board the components must be 0603 sized. The parts are dispensed either using the mounted reels, or the individual manually feed part tape. In order for the tape to advance the parts into the reel feeder system uses servos to run and pull the plastic cover from the SMT part tape.

Directions on how to correctly set up the tape is contained in the instruction manual. The 12 servos are mounted on an equally spaced servo mount shown in Figure 1. Additionally two sides must be created to create a “U” shaped servo mount. Shown below are the aluminium side pieces in Figure 2.

Figure 2

 Regardless of whether the user chooses to use the reels or the individual manually cut strips, the servos must advance the tape and be able to not only collect the protective outer tape film that encloses the parts, but also move the second part into the same position as the first part was in, after the first part has been placed.
Fabrication of the servo mount must incorporate 12 or more servos to be mounted on to a platform above the surface so that they can be programmed and calibrated to turn a certain distance that is calculated to move the second part forward to the same position. The servos are equally spaced in 1 inch intervals. It is important that the servos are positioned at the same distance from the base of the feeder trays. This is to ensure that the individual calibration of each servo is relatively in the same range of motion for turning, and that the force of tension on the tape is relatively similar. This can be seen in Figure 3 below.

Figure 3

The entire platform must be mounted on to two legs that support the servo platform. This is shown in Figure 4.

Figure 4

The servo platform and two sides had to be cut from 6061 0.125 inch aluminium. The aluminium was donated by the SAE. The aluminium was cut using a programmable plasma cutter. The plasma cutter utilizes a DXF file in order to create cutting lines. The part was created in SOLIDWORKS. The part was then converted to a DXF file in SOLIDWORKS. These are shown in Figure 5 and Figure 6 below.

Figure 5

 

Figure 6

The servo mount was drilled in twenty four locations with a drill bit that can accept M3 sized bolts. The servo mount was then assembled using very small M3 sized bolts. The bolts. were fitted with M3 sized nuts, and washers. The servo platform was welded to the two sides using a TIG welder system in order to join aluminium. The welding is shown below in Figure 7 and Figure 8.

Figure 7

Figure 8

After the full assembly has been welded together, and the holes were drilled, now the servo holder can be mounted. It is important to bolt the entire platform tightly to the legs which are bolted to the tape feeder platforms. The servo platform must be placed on the legs at a 45 degree angle. This helps to create a optimal pulling force of the outer tape. The completed servo mount is shown in Figure 9 and Figure 10. The servo motors come with circular discs that attach to the shafts of the motors. Some gorilla epoxy was applied to standard sewing spools shown in Figure 9. The spools are then fitted onto the servos and can now function as a tape cover collector, and as a way to force the tape onto the aluminium table. Information and instructions on how to force the tape onto the table is contained in the instruction manual, as well as the Feeder Tray post.

Figure 9

Figure 10

Pick and Place – Camera Test

By: Kevin Ruelas (Electronics)

Using the interface definitions defined in the camera document. I was able to test the camera to make sure it worked and was taking a photo correctly. The microSD board was a big part of this test as it was required to test the image before figuring out how to send it to Processing and if it was receiving the correct data. In terms of edge detection, I used an open source library called OpenCV. Upon looking at all their libraries I found the Canny edge detection to be the best for defining an edge. The photo is sent 64 bytes at a time and it may take up to 10 seconds for it to completely transfer the photo. From here, calibration code can be written to analyze the photo taken pixel by pixel and reference it to a calibrated photo in order to determine how much the X and Y axis needs to move so it can be at the origin.

 

Pick and Place – Z-Axis and Nozzle Test

By: Tiler Jones (Manufacturing) and Chastin Realubit (MST)

Z-Axis Motor: We did an experiment to see the load that the Z-Axis can handle and we found that it will still carry up to 2000 g. This experiment was done so that we can see if the motor can still move up and down even with more load. This was needed because we are adding a camera on the Z-Axis and we needed the system to still function with extra weight.

As seen on the pictures below, the Nozzle was completely removed due to its instability, the rods were replaced, and wires routed differently to reconnect and replace the nozzle to be stable so it does not move while the Pick and Place is running.

 

Pick and Place – Solenoid Valve Design and Control

By: Tyler Jones (Manufacturing) and Kevin Ruelas (Electronics)

The above Figure 1 and Figure 2 schematics show the solenoid circuit simulated in LTSpice. The circuit on the left shows that when the arduino pin is set to high the circuit turns on allowing the current to flow through drain and source to the solenoid valve. The circuit on the right shows that when the arduino is set to low, there is no current flowing through the drain and source to the solenoid.

This creates an electronically controlled switch, and can be programmed to turn the pump on when picking a part, and off when placing a part. This is vital to the pick and place control system because it needs to be able to switch on using power from the Me Adapter board of +5V, to control a larger voltage of +11.7V from the Me Uno header pins. The IRF 530 MOSFET switches the gate voltage of +4.7V to the source drain voltage of +11.7V This voltage can is now large enough to drive a current to the solenoid and turn it on and off. The +4.7V control voltage from the arduino is programmed to correspond to the following values.

CODE SENT $9 (GCODE) $10 (GCODE)
ARDUINO PIN +4.7V (HIGH) +0V (LOW)
IRF 530 MOSFET ON OFF
SOLENOID ON OFF
SUCTION PUMP ON OFF
ACTION PICK PLACE

The solenoid was tested using an ammeter in series with the Drain of the MOSFET and wire of the solenoid. The current draw shown in Figure 3 through the MOSFET into the load was about 410mA. The turn on current needed to excite the coil in the solenoid was found to be about 310mA. This means that the solenoids resistance value can be modeled most accurately as an inductive coil load in series with a resistive load. The total resistance of the solenoid based on current draw was an operating range of about 24-35 ohms. The circuit works as designed and tested.

The tested circuit shown above was translated into a custom soldered PCB, in order to have the wires and components secured to a fixed location within the electronics housing. The PCB board will be mounted on standoffs inside the electronics housing.

Pick and Place – Updated Requirements and Mass Reports

By: Chastin Realubit (Missions Systems and Testing)

Level 2 Requirements:

  • L2-1: Attached compartments shall not interfere with the functionality of the machine.
    • L2-1a: Wires shall be shielded or incorporate heat shrinks in all areas of the pick and place machine.
    • L2-1b: The RJ-25 cables shall be able to reach every operable part of the aluminum picking surface, while maintaining a standard of bend radii of 2 inches to prevent fatigue while running.
    • L2-1c: All microcontrollers, shields, electronics, and precision sensitive running gear shall be isolated from vibrational or other outside disturbances.
    • L2-1d: Compartments to house, wires, electronics, pumps, tape, and accessories will not occupy more space than half a foldable table.
    • L2-1e: The legs of the machine will be raised so that the cabinet can be placed.
    • L2-1f: The cabinet shall be used to hide the hardware (i.e. vacuum, Arduino, etc).
    • L2-1g: The cabinet should be formed using vacuform to make the machine look neat and professional.
    • L2-1h: The legs of the machine will enclosed with a material that can reduce the vibration of the machine to make it more accurate.
  • L2-2: The camera of the pick and place shall be used to incorporate edge detection technology (used as an alignment camera, the same as the Madell Pick and Place).
    • L2-2a: Pick and place shall incorporate edge detection to determine origins
    • L2-2b: Pick and place will have dedicated Arduino for camera system
  • L2-3: The Pick and Place will include video tutorial, written manual, sample test files.
    • L2-3a: Pick and place shall have detailed instructions on how to operate the machine through the software
    • L2-3b: Pick and place will incorporate LCD to make machine more user-friendly (Display status, component being placed etc.)
    • L2-3c: The user will be able to interface with the machine, and control the machine with an emergency power button.
    • L2-3d: The user manual should include a video to guide users on how to use it. (The video will show step by step how the user will interface with the GUI, where to download all software, and how to turn gerber file into cnc file.)
    • L2-3e: The manual will include a troubleshooting section that will help users fix the machine in case hardware was accidentally disconnected.
  • L2-4: The case should enclose the machine, and hold its weight in a manner of minimal movement when carrying.
    • L2-4a: The pick and place should be remained locked and secure to it location of setup.
  • L2-5: The machine shall be faster than human production time of 4 Hours.
    • L2-5a: Pick and place will incorporate the addition of eight additional servos
    • L2-5b: All part tape shall be managed and hassle free throughout the entire operational procedure of the machine.
    • L2-5c: All parts needed to create a 3DoT board shall be able to be picked and placed within tolerances of + or – 0.2mm.

Mass Report

Vacuum System Components Preliminary Mass (g) Uncertainty (%) Margin (±g) Expected Mass (g) Actual Mass (g)
Stepper Motor (A-Axis) 245.00 5% 12.25 245.00 247
Stepper Motor (Z-Axis) 245.00 5% 12.25 245.00 246
Vacuum Nozzle 2 5% .1 2 TBA
Z-Axis Actuator 292.00 5% 14.6 300 244.12
Detection Camera 3 5% .15 3 TBA
Project Allocation Experiment: The Z-Axis motor can still function after attaching 2000g as a load.

The vacuum will still need to be experimented on to see how much load can be placed on it.

So our preliminary allocation is 2000g

Total Expected Mass 795 g
Total Margin 39.35 g
Total Actual Mass TBA
Contingency  1165.65 g

 

Experiment:

Z-Axis Motor: We did an experiment to see the load that the Z-Axis can handle and we found that it will still carry up to 2000 g. This experiment was done so that we can see if the motor can still move up and down even with more load. This was needed because we are adding a camera on the Z-Axis and we needed the system to still function with extra weight.

Next steps:

We will now need to test the suction of the pump to check if it can carry the ICs that the 3Dot will require of us.

Power Report

Components Expected Current Draw (A) Uncertainty (%) Margin (±A) Measured Current Draw(A)
Stepper Motor (X-Axis) 1.35 5% .0675
Stepper Motor (Y-Axis) 1.35 5% .0675
Stepper Motor (Z-Axis) 1.35 5% .0675
Stepper Motor (A-Axis) 1.35 5% .0675  
Detection Camera .75 5% .0375
Display Screen .75 5% .0375  
Servo fs90r (12) .3 .05 .015  
Project Allocation 6 A (Calculated knowing that we will be using two Arduinos with separate power supplies)
Total Expected Current 3.15 A (The motors and servos will not run simultaneously)
Total Margin .36 A
Contingency 2.49 A

Pick and Place – Servo Driver

By: Kevin Ruelas (Electronics)

The system block diagram presented in the PDR is undergoing changes, especially regarding the additional servos. The system block diagram that was made currently has two micro controllers connected via I2C. Both utilize the Me UNO shield and one port could generally house two servos.

Using a 12-bit PWM/Servo Driver we can hook up all twelve of our servos utilizing just one Ethernet port on the existing Me UNO shield. It would still require an RJ25 adapter in order to make all the right connections.

Figure 1. PWM Servo Driver via adafruit

Figure 2. Makeblock RJ25 Adapter via Makeblock

 A general Ethernet port for the Me UNO shield consists of two digital/analog pins, 5V, GND, SDA and SCL for I2C. For the driver, the 5V (Vcc), GND, SDA, and SCL pins will be used. The 5V (Vcc) from the Arduino is power for the driver, not the servos. So in order to make sure that there is enough power for the servos, an additional battery pack shown in Figure 3 will be required.

Figure 3. 4 AA Battery Pack via adafruit

Figure 4. Block Diagram for the servos

Using this driver would get rid of the Master-Slave micro controller combo and will also enable us to dedicate the second Arduino for an independent camera system. The main Arduino would house all the motors, limit switches, servos, solenoid valve, as well as the new LCD.

References

https://www.adafruit.com/product/815 (Servo Driver)

https://www.adafruit.com/products/830 (Battery Holder)

http://www.makeblock.com/me-rj25-adapter (RJ25 Adapter)