6
$\begingroup$

We have an electric wheel chair, and are looking to add a rotary encoder to each wheel. We don't want to hack the motor itself, so want to add the encoder without harming the motor-to-wheel connection. We will be using an arduino to read the signal.

Does anyone have any experience adding rotary encoders to already assembled wheel assemblies?

$\endgroup$
  • $\begingroup$ Im trying to do the same. But im thinking mounting it under the motors end caps. Where the solenoid brakes was originally. Beside tucked a way from the elements it also would give a much smoother signal or higher definition. If you using sabertooth controller I can show you a board that might helps you. $\endgroup$ – Peter Nov 19 '17 at 15:07
6
$\begingroup$

An optical encoder is fairly simple to add to an existing wheel.

enter image description here

Essentially you mount a photosensor that can detect notches or patches on a disk as it rotates with the wheel. You could use through hole light detection as well.

The circuit design is fairly straight foward enter image description here

And your arduino program counts the number of pulses it receives. Knowing the number of ticks per revolution, and wheel size, you can get accurate odometry.

Another solution that may work for you is add on encoders for DC motors. Their original intent is to make a regular motor a Servo motors, but would work great for this task as well. The only real difference being that a servo motor uses the information in a closed loop to position the motor, as opposed to just keeping track of it.

enter image description here

And one other solution I thought of - if your wheel chair has spokes like a bicycle, then a magnet like this would be easy to attach, and a magnetic sensor, very similar to the above light detection circuit could be located on the chair/frame. That would probably be the least intrusive to implement. If you needed more than 1 per revolution accuracy, just add more magnets to more spokes, as long as they are distributed evenly.

enter image description here

$\endgroup$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.