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With much help here trying to handle speed ramping for a sabertooth 2x25 controller driving the G-Bot last year with limited success, I bought a Kanagroo motion controller in hopes of having it handle the ramping for the differential drive on my B9 replica, the G-bot. I want to use it in speed control / RC mode (only dip switch 1 up). The documentation states the kangaroo REQUIRES at least one feedback signal. I am using two wheelchair motors without encoders on them. I am having a little trouble trying to figure out how or where to add feedback for a B-9 robot using differential drive.

Two questions:

Anyone know if the kangaroo work for speed control without feedback with the dip switches set as above?

If not, any suggestions on what type of encoders and where/how I might mount them?

Any help is appreciated. Smile


I have found a few conversations, tutorials and activities that may help with your question. Take a look at these links. I've sorted them by what I believe to be most relevant but that is not always the case as I'm still learning.

Also, consider reviewing the Learn section for informative lessons and activities. Check it out!


The kangaroo is a smart controller for a sabortooth 2x12 or larger. It handles all of its functions by using either encoders or potiometers. It can also use stop switches but it needs some way to know where the motor is at and how fast the motor is moving.

There are some encoders designed to work with some wheelchair motors. There are some wheelchair motors available that already have encoders in them. Which motors do you have? ( EDIT - asking this question to see if we can find encoders that would fit your motors)

The encoder is normally mounted to the motor shafts on the back end of the motor (the opposite end from the wheel). The encoder should have at least a 4 wires. The kangaroo will work with either 4 or 5 wire encoders.


I will have to disassemble the tread section to get the model number of the motors. I assembled it a few years ago. I'll post again when I know.

Thanks for your input.



If you are using treads, you might be able to place an encoder on one of the rods that are holding the rollers on your treads to accomplish the same thing. Just a thought.


The motors are CM808-75A


I would suggest reading this thread. There are some links to some encoders that look like they might work for you. You will need to measure the diameter of the shaft at the back of the motor to see if they will fit.


Gwen, I've been using these encoders for a while and they do an excellent job. The company offers many different options as far as mounting type and shaft sizes they can adapt to. Do you know what size the shaft is that the encoder will mount to? If you can tell me the shaft size and how you want to mount it I can try to find the proper part number to order. If you can't get it mounted to the motor shaft and have the room perhaps you can mount it on the opposite side of the wheel or gear that is attached to the shaft. You could then somehow attach a shaft to that wheel or gear and then mount the encoder to that shaft. Kinda like I did here:

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