Can I use mBot board to control a Jazzy Chair?

#1

I recently acquired the base of an electric wheelchair. It works perfectly but is not wireless. The power it has is crazy!

I have an mBot from a few years ago that I know very little about to be honest. Life got busy.

I was wondering if I could get rid of the computer on the wheelchair and somehow incorporate the brains of the mBot to control the motors on the chair. It is exactly the same setup of two rear wheels that do all of the steering.

The wheelchair obviously uses a lot more power so I don’t know how to go about it. It has two 12v batteries that are 33 amp hrs. I’m sure it can be done, but I don’t know where to start.

Any help would be greatly appreciated!!!

#2

The mCore board is essentially an Arduino Uno. I suspect the electric wheelchair motors will require some sort of add-on to deal with the power load that is more than the mCore will handle. From a control perspective, you might be able to make it go though using some sort of step-down circuitry and relays. Just some random thoughts (Disclaimer: I am not an electrical engineer and you should probably seek out one. :wink: )

#3

I have seen through some Googling that some have used a Sabertooth board with an Arduino to control a wheelchair. I assume that this is to handle and amperage for the motors.

Essentially I am trying to get to the final result at with the least effort. I know, I know…lazy. It would be nice to use the mBot interface with very little change in code. I don’t even know if it is possible though.

#4

When you say the mBot interface, are you referring to mBlock? That might be more of a challenge because mBlock is essentially Scratch with a custom code generator that calls the Arduino IDE to compile the code behind the scenes.

#5

Yes. My thoughts were to use the board from my mBot along with a Sabertooth 2x32 to control the motors of the chair. The Sabertooth would allow me to handle the increased power from the batteries and power the mBot board as well . The chair is set up exactly like the mBot in that it has two motors with each controlling one motor separately and swivel wheels on the front.

In my head this all works out perfectly. But how many times have I said that in the past on other projects? Lol.

#6

Hmm, off the top if you want to use mBlock 3 (Scratch-based), you’d need to write the Arduino library for the Sabretooth board (if it’s not already written) and then write the extension for mBlock in ActionScript then compile that in Adobe Air. I’m not sure what’s involved with mBlock 5 because I haven’t had time to dig into that area. The major area of concern for me would be to make sure that the mCore board doesn’t get smoked by the voltage and amperage of the wheel chair batteries.

#7

Yeah. That’s what I was worried about too at first. Apparently the Sabertooth has a 5v out to power the board safely.

I am probably wrong, but if I understand correctly the Sabertooth takes the commands in and passes them along with the increased power to the motors. I don’t know that it has to be added to the code library.

Like I said though, I am probably wrong. I am waiting to get it tomorrow in the mail before I dive in too much.

But if that is the case, the mBot board would basically still think it is powering the mBot motors and the Sabertooth will be handling the power.

If I am right…thank god! I have been wanting to learn this stuff for a long time but two full time jobs puts a damper on my time.

#8

Motors are usually controlled via pulse width modulation where the microcontroller sends pulses at a certain frequency. The more pulses, the faster the motor turns. This concept is kind of important because the motors get the same level of voltage/amperage with each pulse rather than actually changing the power, per se.

Here are a couple of articles on building a robot using the Sabretooth and an Arduino (Part 1) (Part2) that you might find helpful although the code is C/C++.

#9

Awesome! Thanks for the help!

#10

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