Week 3

Progress

This week an initial test of stepper motor control and the robot arm logic was successfully completed. Stepper motors will be used to control the height and length of the robot arm, as well as the four-bar block clamp. In the demonstration video shown below an Arduino Uno microcontroller was used in conjunction with two L298N H-Bridge breakout boards to control two stepper motors. An active-low push button was used to trigger an interrupt indicating the start of the robot's turn. An IR break beam sensor was used to trigger an interrupt indicating there is a block to clamp.

Challenges

Initially the design for the clamping system included the solenoid shown in the video below to quickly pull the blocks quickly from the tower once the four-bar mechanism had secured a block. However, during testing it was found that the solenoid current draw exceeded that of the H-Bridge motor driver. The solenoid pulled roughly 2.5A continuous current when driven into the stops, but the H-Bridge motor driver used was only rated for 2A continuous. Because of this limitation, the new design for the clamping system will use a stepper motor instead of the solenoid to pull blocks. A potential issue with the stepper motor design will be stability, and thus the robot arm will be made as rigid and sturdy as possible to support fast lateral movement with minimal arm pitch fluctuation.

Action Items

• ToF and IR sensor testing
• robot structure design concept
• flowchart updates
• block diagram updates
• wiring diagram