Spring 2018 AT-ST Resource Reports (Mass, Power, and Cost)
By: Joseph Cho (Mission, Systems, and Testing)
Verified By: Intiser Kabir (Project Manager)
Approved By: Miguel Garcia (Quality Assurance)
Table of Contents
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
- http://www.custompcb.com/faq.php
- https://docs.google.com/spreadsheets/d/1_q0K2hwcqDshcp3e7MT1azD3lbXh80qJeSJ1bALZQZ0/edit?usp=sharing
- https://docs.google.com/spreadsheets/d/1P0TaSyV01-3muaii-rDUmqtotstaM6gV4AgC4sjzqFQ/edit?usp=sharing
- https://docs.google.com/spreadsheets/d/1j9I_ts227pN5yA5srDkUxOWhMTKYiYWG9uBwJw8IQA8/edit?usp=sharing