wheel tracking

[javalynt344]

My team uses a crab drive for driving the robot. All four wheels are on mounts, which are connected to a chain that goes around all four mounts. There is then another motor that turns the chain, in turn, rotating all of the wheels at the same time.

Anyway, I need some help. I have been trying to figure out how I can track the rotation of the wheels. This way, the driver can see which way the wheels are pointing on the dashboard.

I need help finding out how to do this, do I use encoders, gear tooth sensors, mathmatical equations, etc. Any help would be appreciated.

[RyanCahoon]

Welcome to the forum :) Take a look around, there's a lot of info here already.

While it depends on what kind of crab you're building, what you probably want is called an absolute encoder, which you can think of as like a potentiometer, except that it can twist forever, and outputs the angle from the zero position. My personally preferred brand when it comes to encoders is US Digital, but shop around. Connect it near one of your wheels, so that one rotation of the sensor equals one rotation of the wheels.

Alternatively, if you're using a non-coaxial design, i.e. your modules can only turn a certain number of times in one direction before your cables get wound up, you can use a multi-turn potentiometer, which will allow you to sense where in their entire rotational range your modules are.

Good luck,
--Ryan

[javalynt344]

Thanks Ryan, great idea, I will look into it!