The VEX EDR Tank

Over the last few month’s, I have been building a vehicle out of VEX EDR with the aim of it to self-drive. This is my first big project with VEX EDR, I usually build large stuff out of LEGO Mindstorms or VEXIQ. My view was that VEX EDR would be easier as it is a) made out of metal as opposed to plastic, and b) more powerful. I thought it would take me a week to make the vehicle, and the rest of the time would be on software. I had to also learn ROS (Robotic Operating System).

It actually turned out more challenging than I expected. Due to my lack of experience with EDR, I just assumed metal would just be stronger, and the motors would just work. However the first version of the Tank collapsed under my weight, and it took around 10 versions to get it to move me (95kg) without the motors shutting down after 5 seconds. Unlike LEGO and VEXIQ, EDR motors had a protection circuit in (PTC) which shut down the motor if it gets too hot or draws too much power. This is, of course, a good feature to protect the motor, however, it made my project very difficult.

I went from 8 motors, direct drive to 14 motors geared down to 2.44. The 8 motors could move me at a rapid speed but would just shut down after a few second.

Here is the progress of how it went

Current state

So I managed to get the Tank to a point where it worked, it was not as fast as I hoped however it seems reliable.  Next is the software.  ROS is a big subject to learn, there are lot of books on it and it is not the easiest thing to learn.  I have actually made some good progress on this thanks to the community.  Stay tuned to my next post about ROS.



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