Slippery Wheels and RC Control

This week we made significant progress on the mobile base for the robot. We 3D printed the CAD model we created last week, then attached the motors and tested functionality.

Our prototype base.

We made a simple program to control our H-bridge and drive the wheels. It's hard to see them turn, but they do!


When we ran the prototype on the ground, we realized that we needed significantly more traction than what we had in order for the robot to drive properly. We attempted to use rubber bands, but the shape of the wheels made them impractical.


You can see that our robot wanders a bit in this test. We think that's due to friction differences between the wheels.


When the rubber bands we put on for traction fell off, things got a little...janky.

As a consequence, we decided to redesign the wheels of the robot. We purchased silicone O-rings to provide additional traction.
The two O-rings seat on the wheel, and the wheel press-fits on the shaft.

We also made some minor changes to the CAD model to improve the fits of some of the parts, as well as to add stability to the motors. We hope to have the shell of the tank snap onto the base. This way, multiple shells could be designed to interface with the same base. We’re finding that 3D printed snap fits, however, are a lot harder to do than we thought!

This week we also connected the H-Bridge to the motors and were able to run them using the joystick. We discovered that our joysticks rail to GND or 5V of output with minimal input, so we determined that we’ll need better hardware for the final product. The joysticks we have now are sufficient for prototyping purposes. We also connected the turret control to momentary switches.

Our two circuits function independently, able to communicate remotely. We have yet to nail down the algorithm to convert joystick position to the correct speed of each wheel.
Overall, we are making great progress! Apart from waiting from for parts for our remote controls to come in from China, we are far ahead of schedule.

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