[StavrosK]

That makes sense, thanks! Regarding the build, I didn't see any information regarding the control system on the material I saw, but I probably wouldn't want to make it as autonomous as you have. I'd probably connect an ESP8266 as the controller and a receiver for my RC radio and control it that way.

Out of curiosity, is there more detailed information about the controller somewhere?

[TaylorAlexander]

Well do you mean the motor controller, the control computer, or the remote control?

I’ve got some info on the motor controllers I’m using: https://reboot.love/t/vesc-mods-for-robotics-use/

The control computer is a raspberry pi running python. It looks like I’ve not committed the code in a while, but this repo may be helpful: https://github.com/tlalexander/rover_control

Though for the above, I’ve recently found that I can use velocity control on the VESC, which is easier than doing velocity control on the Pi as I had done in that repo.

For the wireless remote control I use, it’s my own design and they’re not for sale or well documented. I’d recommend any wireless controller that you can read in python.

The software should be pretty simple now that I’ve switched to velocity control mode. You just need to read a joystick and convert that to velocity commands for each VESC. Technically even the VESCs could do that onboard if you wanted to modify the firmware.

But if you can drive the VESC from an esp32 that would work too.

[StavrosK]

Oh huh, that's pretty involved, thanks. Can I ask why you rolled your own instead of using off the shelf RC components, like what is used in RC cars, for example? For the remote control and ESC, at least, it seems like it would be simpler.

[TaylorAlexander]

Well for the remote control, I already had the one I used. I started a wireless electronics company in 2013 (and eventually failed), so it’s a point of pride to use my own remote. But any RC remote would work.

For the ESC it’s more complicated. The VESC is off the shelf, but it has a feature most ESCs don’t. The VESC supports encoders. The use of an encoder is very important to get full motor torque on the brushless motors even at zero velocity. This allows Rover to slow down or stop even on a slope. The encoder is also used for precise velocity control, which keeps all the wheels spinning in concert. Additionally, the encoder data is sent up the CAN bus to the raspberry pi so my program knows wheel velocities.

You could certainly build a rover without encoders and with a regular ESC, but it may have trouble starting from a standstill and it may not always drive in a straight line if the wheel velocities are not all the same. Another thing to note is that if you spin the motors really fast you’d probably melt the gearboxes. I’m moving the motors pretty slowly compared to their maximum speed. But a regular ESC might work fine! I’ve not tried it.

[StavrosK]

That's very helpful, thank you. So you're basically turning the brushless motors into stepper motors with the VESC, that's very interesting. Again, great project, congratulations.