Hi folks,
I’m working on a new rover style drive unit to attach different impliments to, mower, plow, trolley etc.
I’ve sourced 2 electric scooter type motors, I’ve wired them up to a Sabertooth 2x32, they are being chain driven and attached to 2 x 12 inch mini-motorbike wheels.
On a basic level, everything is wired up and running, things are working, BUT, where I’m struggling is the fine tuning aspect of it all.
A few issues I’ve noticed from the get go;
-
The right motor/wheel spins faster than the left, they are the same brand new motors with the same settings in the Describe software. Is there a setting I can change to make them identical? (I seem to remember my Roboclaw had such a setting?) - the chain on the left may be slightly tighter than the right, would that cause this?
-
If I put my foot infront of the rover as to block its path and stop it from moving it has what I can only describe as a “freak out” where it starts to go left/right/back/forward … anywhere BUT where I’m telling it to go, is that a regenerative issue? or volatage clamp issue? (complete newbie here!)
-
The motors I’m using are a little overspec’d, 450w/28a/2600rpm, any easy way to limit their rpm? - only running them at 12v for now.
I’m totally open to any help, thanks for reading folks 
@AussieBloke
- The right motor/wheel spins faster than the left, they are the same brand new motors with the same settings in the Describe software. Is there a setting I can change to make them identical? (I seem to remember my Roboclaw had such a setting?) - the chain on the left may be slightly tighter than the right, would that cause this?
It’s very rare that two geared motors will spin at the exact same speed, and even if they did, differences in the terrain would cause them to differ over time (friction etc.). This is where encoders come in - they measure the rotation of each motor and these are communicated to a microcontroller which then in turn communicates with the motor controller to adjust the speed. Without that setup, you’ll just need to change the input from the RC remote and/or output range to the motor controller until they are “roughly” equal.
- If I put my foot in front of the rover as to block its path and stop it from moving it has what I can only describe as a “freak out” where it starts to go left/right/back/forward … anywhere BUT where I’m telling it to go, is that a regenerative issue? or voltage clamp issue? (complete newbie here!)
Not sure. Really sounds like a control or wiring issue where the motor stalls, then starts back… would need to see a video.
- The motors I’m using are a little overspec’d, 450w/28a/2600rpm, any easy way to limit their rpm? - only running them at 12v for now.
The Roboclaw controller is what would limit the RPM. Running them well outside of their nominal voltage likely greatly reduces their efficiency.
