Arduino control of 4 wheelchair motors?

I want to build an offroad/all terrain mobility vehicle and have simultaneous motor control using an Arduino, raspberry Pi, or similar mini board. I have very limited mobility and want to enjoy the outdoors more. Can this be done?

I have 24volt motors, but not sure yet as to the watts.M

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iceng1 month ago

Understand a pair of ten pound gear motors which are probably 150 watts each.. Also, older wheelchair motors were 12 VDC though 24 VDC are preferred because of semiconductor forward drop... (Example batt volts; 240 watts at 12V is 20A and a simple 0.7V semiconductor wastes 14 watts BUT at 24V is 10A and that same semiconductor only wastes 7 watts)..

I strongly recommend you avoid laptops...

rickharris1 month ago

Such things do exist although I think the problems of building one are considerable.


However, to answer your question you need to look for Pulse width Modulation (PWM) control. you will neeed some BIG FETs to carry the power for such big motors.

poppaIT (author)  rickharris1 month ago

This video is a very good starting idea as well as something called "terrainHopper" which is manufactured in Germany, I think. I understand a little bit about PWM but know 'very' little about FETs at this point....are these BIG FETs something that can be reclaimed off other electronics? Also, I still need to address whether a mini control board such as the Arduino can handle the task.

iceng poppaIT1 month ago

Field Effect Transistor works on voltage control signals as opposed NPN, PNP, bipolar transistors that work on current control signals..

Pulse Width Modulation is depicted with an NPN Darlington bipolar and the preferred MOSFET MetalOxideSemi-FET.

MotorPWM.gifpwmFastMotorController555.jpgPWM-Mid.jpgPWM-Low.jpg
iceng iceng1 month ago

Yea,.. Be sure to click the pics to see the whole circuits

How FAts work. You will be using them as high speed switches.

However if you use brushless motors your in a different field.

poppaIT (author) 1 month ago

My apologies for not giving more detail in my initial question(s) here and I sincerely appreciate everyone's feedback, but I'm trying to ascertain can I/how/if/how much $$ to design my own controller using an Arduino, Pi, or other mini dev board. Essentially, I want to take modeling with electric motors to a much larger scale; I could also incorporate the use of one or more desktop or laptop computers.

iceng1 month ago

How heavy are the motors and do the have a small gear box ?

poppaIT (author)  iceng1 month ago

It's been my experience that wheelchair motors come with at least a simple gearbox for engage/disengage functions and some sort of ratio increase/decrease. The adult mobility scooters that I have use a single 700watt 48volt brushless motor, attached to a transaxle using planetary gears, and solid axle tubes.

The wheelchair motors weigh about 10# each (+, -) a couple of #......It's the weight of the batts for those motors that'll kill me the most.

In theory everything is possible, done this already so it is confirmed ;)
But electrical is a big problem in terms of weight and range, especially if you need to drive on gravel or similar loose surfaces.
A typical mobility scooter has one or sometimes 2 motors on the rear axle.
They come in 24 or 48V, modern oves might use even higher voltages.
The power they consume is between 300 and 500W per motor!
So if you need to drive 4 of them you are looking at 1kW already and I doubt you have enough room for the batteries required.
One option would be to use lithuim ion batteries if you can afford it but of course they need special chargers.

We got around all this by using a leftover model airplane engine that drives a small alternator when required.
Not enough to get to a decent speed but good enough to make it home a bit slower if the batteries run out.
A modern alternative might be to use a smal ATV instead of a mobility scooter.

poppaIT (author)  Downunder35m1 month ago

I own several mobility scooters such as the cm-72 by Charged Mobility, which uses a 700watt 48volt brushless motor. The ECM is rated for a 500watt motor which makes me suspicious from the get-go. I had to purchase a replacement controller for one machine and it cost me around $300.00 out of pocket. So, I am also curious if I can incorporate an Arduino or such when I have future issues. In terms of my original question....Two of the donor motors are coming out of a "Promobil c400" powered wheelchair along with the joystick controls and electric actuators. There are so many applications for the raising of the seat, such as seeing above large crowds, elevated gardening in my backyard, star-gazing...I could probably get by with just two 900watt motors on limited-slip diffs, but the idea of one motor on each wheel is alluring.

I'm also considering solar power to keep the batts up on charge, if I can generate enough charging amps quickly enough before depletion of them.

+1

I concur..

Maybe not ;)
There is the option of using brushless motors of the really high speed kind in combination with a proper reduction gear, like a planetary gearbox.
Correctly matched these systems can deliver the same torque as conventional systems but at less than half the power consumption.
At least until you start to max out the motor.
Downside for a big system like this is that you can no longer use standard motors as used for model cars or quadcopters.
This means costly, especially if you have to experiment to get it right.

The principle is similar to the modern cordless drills using brushless motors.
But instead of aiming for a balance of torque, speed and max power consumption for the battery run time you opt for minimum power consumption together with a high speed motor and bigger or multi stage gear box.
But considering the costs of making a trailer with a generator to charge the batteries on the go it is only for those with enough money and the need for something fancy.