By: Samuel K. Yoo (Electronics & Control – Software)

Verified By: Intiser Kabir (Project Manager)

Approved By: Miguel Garcia (Quality Assurance)

Introduction

The main objective of this code is to make the robot follow a line. The initial part of the program has two motors turning wheels to move forward. After accomplishing this first part of the code, the next is to create the line follower. There would be four sensors not touching the line, and if the sensor hit the line, the robot would swerve away and continue to head straight. The AT-ST would not use motors for forwarding motion, instead, it uses servos. The four sensors will still be the same for the AT-ST.

Code

Figure 1: Code Screenshot

Figure 2: Code Screenshot cont.

Explanation

The beginning of the code initializes all the pin definitions and the I/O for each pin.  After that part of the program, the main loop contains the movement code. This code allows two motors to spin in opposite directions, attached to the wheels to move the robot forward. However, this movement code will be modified at a later date, as the AT-ST uses servos. The servos do not work like the motors and require a lot more analog pins. These pin requirements will need an analog extension. The sensor reading code, however, can mostly stay the same. The concept of slowing one part and increasing the speed of the other part will stay the same. However, it would not be the torque but the movement of the leg. Another huge difference in the code is the values. If this program would run on a robot right now it would crash or not move straight at all. This is because each motor is made with different values. There is no minimum value for the speed and the delay values might be too long.

Conclusion

So this line code main purpose is to move the robot forward and to follow a line. One of the issues is the AT-ST does not use motors for movement, it instead uses servos, which at the moment of this blog post, there is no research on. Another issue is the values inside the code are not accurate. These values need to be tested in real life to get value for the code. Overall, the general idea of the code in this blog post, however, needs to be updated with servos code and the real values in the final code.  

By: Joseph Cho (Mission, Systems, and Testing)

Verified By: Intiser Kabir (Project Manager)

Approved By: Miguel Garcia (Quality Assurance)

Introduction

The resource report contains three parts: Mass report, power report, and cost report). These reports will be covering the resources’ mass, power, and cost. An estimate of the total mass will be shown on the mass report. For power report, the current values were taken from previous projects’ blog posts as reference. Lastly, cost report will show that the AT-ST project is within the budget.

List of Parts

• 3DoT Board
• Bluetooth: HM11
• Dual Motor Driver: DRV8835
• (2) Motor: 50:1 Micro Metal gear motor
• (2) Servos: HTX900
• (2) Shaft Encoders : Pololu product 3081
• I2C Expander: TCA9548A
• Gyro : GY-521 (MPU6050)
• Ultrasonic: HC-SR04
• IR LED 1 (rated for 16~18mA)
• Light sensor 1: Si1145
• IR LED 2 (rated for 16~18mA)
• Light sensor 2: Si1145

Mass Report

Figure 1: Mass Report

Description:

Comparing our AT-ST to last generation of velociraptor, the mass will be around 800g. 3D printing mass is estimated on the mass report blog post. Since the custom PCB will be made with the same materials with 3DoT board, we can estimate that the mass of the PCB will be similar to the 3DoT board. Our main PCB is slightly smaller and two other sensor PCB are half the size. Further more information about how the masses were estimated and weighed are in Mass report blog post. There are also couple of measured weight as 0. This is due to those parts being included in the body of the mass measurement.

Power Report

Figure 2: Power Report

Description:

The power report shows the expected current draw needed from the power supply. Each servo is rated at 270 mA with a load. The 3DoT board current draw is also counting these parts: Bluetooth and dual motor driver. Measured currents have been added. The motor uses 29mA with load and 170mA when stalled. Power budget was used to determine if a battery with higher capacity was needed.

Link to Power Budget

Cost Report

Final Cost

Figure 3: Cost Report

The cost report shows the total expected cost to be slightly more than half of the budget. After totaling up the spendings, we are still under the budget of $250. There are some components that are given or borrowed; therefore, the actual cost is zero for those items. Our total cost for the AT-ST materials is $199.58 with shipping included.

Extra Cost

Figure 4: Extra costs (included in Cost Report)

Description:

There were additional costs to AT-ST, but not included in final cost report because these resources were not used on the AT-ST.

Conclusion

The reports show that the AT-ST had all resources within the project allocation. The final mass of AT-ST was 256.80 grams, which is very light compared to 2nd generation of Velociraptor. Total cost of the final product was $199.58 and the prices could have been lowered if parts were ordered earlier.

Resources

1. http://www.custompcb.com/faq.php
2. https://docs.google.com/spreadsheets/d/1_q0K2hwcqDshcp3e7MT1azD3lbXh80qJeSJ1bALZQZ0/edit?usp=sharing
3. https://docs.google.com/spreadsheets/d/1P0TaSyV01-3muaii-rDUmqtotstaM6gV4AgC4sjzqFQ/edit?usp=sharing
4. https://docs.google.com/spreadsheets/d/1j9I_ts227pN5yA5srDkUxOWhMTKYiYWG9uBwJw8IQA8/edit?usp=sharing