Jul 192014
 

Lately I’ve been getting less joy out of my wheelchair joystick.

As my upper body strength has declined, I have found it more and more difficult to control my wheelchair using a conventional joystick. I am able to maneuver the chair okay but when I first take hold of the joystick I need to sling my arm up and around and let it drop onto the knob. Frequently that results in me jerking the joystick in one direction or another and running my feet into a wall or backing the chair into furniture. A few months ago, my physiatrist at the MDA clinic recommended I be evaluated for an alternative control system. After trying several of them, I decided that my only hope was to try to design one myself. Before I show you my concept, let me explain what I found wrong with all of the others that were available.

The first idea was a micro joystick that would require much less strength to operate. However it had a very short “excursion” in other words the distance from zero movement to full speed was something like 1/10 of an inch. Also, it was designed to be moved with a finger. Those of you with IBM will immediately see the flaws there as our fingers are among the first parts of our bodies to lose strength. I could barely get the wheelchair through the door out of my room to try it out. Even when I tried to use my thumb, the amount of fine motor control needed far exceeded my capabilities.

The next experiment was a device that would be controlled by my chin. Once again my weakness got in the way. If I reclined the chair at all, my head collapsed back into the headrest and I no longer could even reach the chin control, let alone operate it. However this control did have a longer excursion and therefore I was able to at least get the chair out the door but I found it extremely difficult to keep it going in a straight line. Furthermore any distraction to either side that caused me to turn my head also turned the chair. Picture that happening while you’re going down a sidewalk with a steep curb!

There is another type of control that is similar to the chin control and that is a head array. We determined that it would have the same failings as the chin control for me.

There are other, more extreme types of alternative controls such as the sip and puff which uses your breath for control (another of my weaknesses). One that sounded fascinating was a trackpad system which would be very similar to using the mouse on a computer. Hwever it relies on being able to control your fingers which I can’t.

In this proposed control, my thumb rests on a miniaturized joystick. My remaining shoulder muscles would slide my hand forward and back for controlling wheelchair speed while my thumb muscle (the only one left in my hand) would control the direction left and right.

In this proposed control, my thumb rests on a miniaturized joystick. My remaining shoulder muscles would slide my hand forward and back for controlling wheelchair speed while my thumb muscle (the only one left in my hand) would control the direction left and right.

So now we get to my proposed solution. I need a flat panel to rest my hand on when I first reach for the control. I have the most strength in my thumb, so it would be ideal if the joystick were waiting for me near, but slightly forward, of where my thumb would normally rest on the flat panel. I could then make a motion quite similar to the same one I use when I am controlling the mouse on my computer. I have become skilled with those motions out of necessity.

Access Medical sent my design to a company that specializes in making alternative wheelchair controls and I will let you know if they are able to come up with something for me.