Electronics > Electronics

Jazzy select motors and motor controller interfaced for RC

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headrc:
Hi everyone ....a Newbie here.  I recently acquired a Jazzy select electric wheelchair that I want to use the motors, batteries and possibly other electronics for a RC controlled lawn mower (and other tasks).  I have not been able to find an answer to this question.  Why would I have to buy something like a Sabretooth motor controller when there obviously is one in the Jazzy.  Could that motor controller not be interfaced with an RC set and be controlled by it?  I know I may be missing something here ....but if it can be done ...it saves another $140 or more to do what I want to do.  Great forum here ....and I know I will learn a lot !

jlp:
I also acquired two motors, wheels (12"), a controller, and joystick that I have just started to build a robot with.

The motors are 24v @ 3amps, 100rpm. Took the controller apart and it uses 8 N-channel MOS fet's. (2sk1426)

I am doing the same thing that you are going to do. This is where I am at now. Built a frame using angle iron just bolted together. Everything works the way it should, of course everything is controlled for safety reasons.

Testing in the house wasn't a good plan, got hole in wall that I have to fix now.

Went to radio shack and bought a RC car for the plastics of the controller. (30$) Took the controller apart and there is lots of room for modification. Gave the car (red porche) to the neighbour's kid.

This is my plan to make it wireless, after I take some measurements for this motor controller.
I will be using 433mhz transmitter and receiver along with the pt series encoder and decoder. A few bucks.

I will be using the attiny4313 that has 4k of flash and built in PWM. I have all the parts, just time now involved.

I have two controllers so I am going to cut the fet's off with my bandsaw keeping them attached so I can screw it back to the case. (heat sink)






headrc:
So you are using the original motor controller from the wheelchair then.  Still trying to figure out why others don't do this.  Candidly, I am not technically up on everything you outline here.  I will probably have to get to that point ...but would like to know if I could not just purchase an RC set made by someone like Futaba and get everything under control using the wheelchairs motor controller.  I know I could buy a Sabretooth or equivalent motor controller and I may end up doing this if the motor controller from the wheelchair cannot be used without a lot of hacking (and learning how to do this). 

jlp:
I think why ppl don't do this, is that you are at the mercy of the controller such as speed and acceleration. For example, with my unit there is a switch on the joystick, off, drive a, and drive b. When I switch to drive a, then I move the joystick forward, the acceleration and speed are predefined by the software (firmware). Same with drive b. With turning, left or right to the extreme, it will spin in a circle, one wheel forward and the other reverse, also the speed is reduce for safety reason. Lot of design put into these controllers for safety.

With that being said, I am going to do what you suggested and use my cheap RC transmitter and receiver for basic control. I took my transmitter apart, there is regular speed and turbo speed, on or off, same with left or right, nothing fancy, servo will turn hard left or right. Put my Oscope and there was nothing to measure except on or off.

Checked out the Futuba online but could not find any technical info on them. I am sure there is other members that can help us there.

Will take some more measurements of motor controller today to see what will be involved to hook up receiver. 

headrc:
Hi again ...you are certainly a lot more knowledgeable than me (as many others here are) regarding the whole electronics aspect of this.  So anything you discover on how to do this please let me know.  Another thought going through my mind is to just sell the wheelchairs motor controller on fleabay and use the funds to buy something like the Sabretooth motor controller.  They seem to be pretty easy to set up ...and for a newbie I like that.  If I could basically do a swap that way with no major cost it could make life simpler ...unless it turns out hacking the existing wheelchair controller is no big issue.  It would be nice to also have this thing under manual control as well ...which would be an advantage of hacking the wheelchair motor controller.  My application for this thing when up and running will be taking it over some fairly rough terrain at times so I definitely to make sure it is under good control.  As far as RC set .....I have not done a lot of research there yet.  I just poked around and found the Futaba and it seems to be a recognized name and commonly found ...which indicates possibly something used might also be found that will do what I want to do.  In my reading it seems that PCM is the best method for what I want to do ....so I am looking for that first unless I am guided otherwise.  Thanks for the response and please do let me know what you discover.

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