Team Vision for Subsystem-Level Design Phase
After our last design review we decided to work towards an updated leg design, full electrical system diagram, and begin prototyping of electrical system components. We have modeled the leg design with both motors and actuators, tested the second revision of Tigerbot V’s ADC PCB, and have created a test plan to be initiated by the end of MSD I. We intend to choose between actuators and motors, create a lower body design, and have a full circuit schematic for the next review.
Action Items from Systems Design Review:
- Begin design process
- Acquire all 15201 materials
- Achieve Final understanding of 15201 materials
- Begin ordering parts
Feasibility: Prototyping, Analysis, Simulation
ADC REV1 TEST
Purpose of Test:
To ensure proper functionality of the ADC rev1 board
The ADC board will be connected to the Arduino using the main connector (bottom left, next to MC). There are five connections made; two address select (SDA and SDL), two supply power (5V and 3.3 V) and the ground. Then the test code is compiled to check the ADC for proper voltage selects.
Description of Code
This code is for testing the basic functionality of the ADC128D818 chip, on the Tigerbot V ADC PCB Rev1 by Ben Haag. It reads the input voltage on the In_1 header, and prints the result to the Arduino serial terminal. It assumes that the address is set to 0x1D, and an external reference voltage is being used. These settings can easily be changed within the code. There is a lot of room for improvement in this code, but its only purpose at this point is to verify that the board works correctly.
Result of Test
After the completion of the code, the serial terminal showed the proper voltage reading ( 3.3, 5.0 or 0) depending on which pin the connector was on. The figures below show the code and the result terminal.
Necessary ADC Board Changes
ADC Board Rev 2
Actuator and General Torque Analysis
We will be using a similar method to 15201 to calculate required torque to each joint, but will replace their worst case scenarios with a more conservative method involving the full range of motion of the Tigerbot. Once 3d models are somewhat finalized we can update and change this spreadsheet to accommodate our designs and our torque estimation method.
Drawings, Schematics, Flow Charts, etc.
Electrical subsystem Diagram
3D models (WIP)
Nick (actuator method)
Motors and gearboxes:
During the modelling process, several problems were found:
- No actuators fit our requirements "just right"
- In order to achieve required torque, speed must be sacrificed, and vice-versa.
- No middle ground has yet been found among commercially available linear actuators.
- Decision on path forward will be made soon. (Within the week)
AJ (motor method)
Full Lower Half View:
Front Ankle View:
Side Ankle View:
Front Leg View:
Side Leg View:
Top Torso View:
Bottom Torso View:
Bill of Materials (BOM)
Risk Assessment Snapshot
15201 Item Search Update:
We are still in the process of pulling together materials purchased by 15201 team. As we find pieces, we have been moving them to our team locker on the Senior Design Center floor. To date we have 15201’s machined leg, a power supply for testing, an extra cycloidal gearbox, and an ADC PCB (rev. 1). There is also one Tigerbot V Teensy board being used in Tigerbot II in the robotics lab.
Design Review Materials
Plans for next phase
For the next review we plan to:
- Continue and complete testing of available electrical components
- Finalize lower body designs
- Begin prototyping mechanical components
- Amend the test plan as necessary
- Finalize BOM and begin ordering parts