motor drivers for a electric wheelchair

[andd64]

Hey guys,

I have in my possession an old "fortress" electric wheelchair, except everything is stripped but the base (the wheels), the motors, and the battery.  There is no model information anywhere on it - i tried looking online for schematics but this brand of wheelchair is no longer operating, and there's absolutely no information.  Only markings i found on it was a sticker with this information: its 2.2 (could be a 1.2, the stickers really old) Amps, possibly 183 RPMS (this seems low though).

Does anyone know what kind of motor controllers i can get that will work with this? I have no other information about the wheelchair. 

[ArcMan]

2.2 A does seem low for a wheelchair motor.  The wheelchair motors on my yard robot are 24 VDC @ 11 A full load.  I use the Dimension Engineering Sabertooth 2X25 for them.  There are other drives out there, but the Dimension Engineering drives are well-engineered.  It's amazing to me that some other drives are rated for high amperages like 25A but only have terminal blocks rated for 10A.  Buyer beware.

[dsheller]

I agree with the above, those are some good drivers... as for the markings. I highly doubt it's running at only 2.2 A...  Also, are you sure there isn't a gearbox attached that is gearing it down to 183 RPMS?

[andd64]

Also, are you sure there isn't a gearbox attached that is gearing it down to 183 RPMS?

i have no idea about the gearbox, it could be a possibility, i'll try taking a picture of it sometime this weekend and putting it up.

I use the Dimension Engineering Sabertooth 2X25 for them.  There are other drives out there, but the Dimension Engineering drives are well-engineered.

Will any driver from Dimension Engineering do? Can you suggest any that are "generic" enough for me to use?

[dsheller]

Dimension sells different size drivers for different motors... you're going to have to find out what the stall current is on that motor before you can pick a suitable driver.

[ArcMan]

That's definitely the best course of action.

But if you are not able to determine the stall current of you motor, you should be safe with the 2X25 for wheelchair motors.  They're not going to draw > 25A each.

[Admin]

They're not going to draw > 25A each

not guaranteed . . . get some batteries and hook it up directly to the motors, and then measure the current draw under load

[airman00]

I recall that someone made a motor driver PCB on the forum. I don't remember if it was for this kind of high amperage or not .Anyone remember ?

[andd64]

so i decided to get the sabertooth 2x25 motor drivers.  but before i buy them i need to ask you guys one more thing - i need to connect a joystick to the wheelchair, the problem is that it currently doesnt have the joystick or any wiring.  Is there any website/info you guys could give me on how to connect a joystick to what to drive the wheelchair?  Lets say i want to do this without a microcontroller if that's even possible.  Also any recommendations on where to get the joystick? Or maybe its better to get it from a dump.

[ArcMan]

You will definitely need some kind of "translation" control system if you use a single joystick.  You will have to convert the joystick's left/right/fwd/rev inputs into differential drive signals for the motor drive.  A microcontroller is very well suited to this task.

I'm sure you'll want an analog type joystick to give you variable speed control.  Google is your friend.  There are many analog joysticks out there.

[hudbrog]

About joystick... I really enjoyed interfacing playstation 2 gamepad to microcontroller(and it is really easy. took me less than hour to write ARM code and processing sketch). And you'll still have lots of additional control elements for anything you'll ever want to attach to your chair.. like rocket launchers or anything )

[andd64]

hmm ok so if i get the dimension engineering drivers, i would connect the drivers to the motor and the mcu, and the joystick directly to the mcu? or would i also connect the joystick to the motor drivers?

[hudbrog]

joystick only to mcu.

[Admin]

hmm ok so if i get the dimension engineering drivers, i would connect the drivers to the motor and the mcu, and the joystick directly to the mcu? or would i also connect the joystick to the motor drivers?

Instead of a mcu, another option is to buy a remote control and receiver. You can hook it directly up to the sabertooth without a mcu. Any rule against a remote control joystick?

[andd64]

Admin would this be done through infrared?  That sounds like a viable idea - but i can't imagine this.  Please explain?

[Admin]

Nope, through RF.

Its the same remote control system used for RC toys/planes/etc.

Basically you will have a remote control wheelchair.

Here is a perfect example:
http://www.societyofrobots.com/robotforum/index.php?topic=5442.0

[andd64]

Here is a perfect example:
http://www.societyofrobots.com/robotforum/index.php?topic=5442.0

That is a great example - the problem is i want to stay away from batteries and have the joystick controller powered by the wheelchair battery.

I really enjoyed interfacing playstation 2 gamepad to microcontroller(and it is really easy. took me less than hour to write ARM code and processing sketch). And you'll still have lots of additional control elements for anything you'll ever want to attach to your chair.. like rocket launchers or anything )

hudbrog that sounds pretty cool, do you have any more information about this?  Like what would i connect where?

EDIT

nvm hudbrog i found a lot of stuff online and even on SOR to explain how.