Wheel Chair Motor Controller

Ok I received my new wheel chair and now I want to interface my arduino with the controller from my old chair. The cool thing is the Microcontroller portion is a seperate board from the power control circuitry. But I want to play with both! My problem is I am unable to find any info about the controller no schematics nadda! :( Where do I begin? oh and how do I upload pics?

Also from looking up some of the components it looks like this thing will handle up 40v and 10a cont.

SubMicro

how do I upload pics

Put the pictures on a sharing web site like flicker. Copy the ULR and then click the third icon from the top in the reply window and paste the URL between the two commands that appear.

It is likely that the schematics don't exist on the web. However, a start would be the manufacturers name and that should be on the PCB. Failing that the part numbers of the components will give you a clue. For example the one with the most legs is probably the micro controller.

Then for the motor control board you could always trace a schematic from the PCB board given a multi meter.

Thanks grumpy sounds like alot of work to trace the board. I've already located the Microcontroller. I'll see if I can get some pics up.

Here ya go

I'm tried but no luck on pics. I can't seem to get them to show up so i'll post the url

http://www.flickr.com/photos/33536645@N06/

To post you need to put the URL of the actual photo in the links for you just do:-

img http://farm4.static.flickr.com/3265/3120067363_8777bdce7e_o_d.jpg /img

Only replace the stars * with straight brackets [, this is because it I use the straight bracket the it would display the picture and not the line of code. Even so it is picking up the http and treating it as a link.

Also those controllers look like two FET H bridges.

Thanks for the tip. I'll give it a try

I was posting the wrong link like you said thanks heres the controller board for the dual H bridge

It was actually this one that looked like the H bridges:-

Shouldn't I be able to use the H-bridge board with the arduino it has a 34 pin header which plugs into the controller board right below that yellowish chip bottom middle of pic.

If I supply the H bridge with 12V then supply a PWM signal to different pins on the connector that attaches to the micro-controller board would this help me figure out the pin out? i.e. pin 12 ccw left motor 13 ccw right motor etc... :-/

That sounds good although I wouldn't use a PWM signal but just a straight logic one and zero to start with. The PWM signal only complicates things that you don't need complicating at this stage.

Remember there may be more than one signal needed to get it going, there might be a go signal, a direction signal and an enable signal. All need driving at the appropriate logic levels.

Thanks Grumpy

That makes sense, you just saved me hours of cursing and desk slapping! ;D

Hey Grumpy As I was putting off the tedious task of checking the pin out. I had an idea, what if I hook the digital IO pins from the arduino to the H brigde couldn't I write a little program to go through and give each pin a high and then low signal? And somehow keep a log of which pins did what? :o

Rather than trying to randomly hook up arduino, you might try to observe the signals sent by the original controller to the power board. Hook up the original controller to the power board, tell the motor to move a direction, and observe the inputs.

If you don't have a scope, you can make a simple logic probe with a led (or flashlight bulb) and some wire.

Good idea! actually that sounds obvious, why didn't I think of that in the first place? DOH! sometimes I'm such an idiot! :-?

I have the same problem and it looks like I have the same wheel chair controller. My problem is I don't have the joystick interface to figure out the logic that controls the motors. I believe this controller is using PWM via the joystick interface, but I can't be positive. Did you ever figure out the control pins from the H-bridge board? If I can find a cheap joystick for the controller I should be able to help you out with the control signals.

I realize that the hacking aspect of this might be what's holding your interest, but if you just want to control the motors here's a great option: http://www.trossenrobotics.com/store/p/5105-Sabertooth-dual-10A-motor-driver.aspx

It has a lot of fully documented interface methods, and even does regenerative braking. There are other options with more amps and control features, with somewhat higher prices. Pololu has some nice ones, I used one of these to control a large gearmotor as a steering servo on an electric car project: http://www.pololu.com/catalog/product/425

This is another decent controller: http://www.pololu.com/catalog/product/1112

This post is fairly old but I stumbled on to it looking for a motor controller for a wheel chair sized motor to be controlled from an arduino and figuring others might do the same i thought I'd add that none of the controllers mentioned are anywhere near robust enough for a wheel chair motor - e.g. they may actually run the wheel motor fine but I'm fairly certain that pushing any normal wheel chair motor anywhere near stall will fry all of these controllers very quickly. Most wheel chair controllers i've seen (which is only 3 or 4 but enough to see a trend I think) are built for ~120A per leg (3 very Heavy Duty MOSFETs like an IRF1405 per leg of H-bridge) with the smallest one I've seen in a wheelchair built explicitly for children with only 2 MOSFETs per leg probably putting it at ~80A. OSMC seems to be the defacto standard for this type of application and is conservatively rated at 160-200A as it contains 4 MOSFETs per leg each spec'd to well over 100A - e.g. 16 transistors per H-bridge! So getting a 10A or even 25A version of the controller is substantially lighter duty than what is probably necessary.