Suddenly the chair looks smarter and I am the one with the control issues

by Michael S. Kaplan, published on 2009/07/08 10:01 -04:00, original URI: http://blogs.msdn.com/b/michkap/archive/2009/07/08/9823397.aspx


Just about every day I learn new things about the iBot.

Mostly it is just consequences stuff, like when I think through logically how it works I understand why this new understanding is something that just logically makes sense.

And of course each day, as one becomes smarter, one realizes how dumb one was the day before....

Like way back in From I SCOOT to IBOT, #2 of ??, where I mentioned

I decide to slip down to standard mode for speed as soon as I hit the walk outside the apartment . It's faster (up to 6.8mph!) with a bit less control, but good for wide open spaces when the best thing you can do is move through the place and on to some place interesting.

Now if you search on the web, you will find other people making the same observation about standard function in the iBot. People pretty routinely talk about how the control of the iBot in standard simply isn't as good as the other modes.

Now fast forward to From I SCOOT to IBOT, #7 of ?? (Unintended movement of the joystick will result in unintended movement of the product), and the diagram from the manual.

This page:

http://www.trigeminal.com/images/ibot_steer01.jpg

or more specifically, the following small part of that page:

http://www.trigeminal.com/images/ibot_steer02.jpg

Now speaking as someone who grew up accustomed to joysticks, I know how they work.

I have logged countless hours in video arcades, with Atari 2600 and 5200 consoles, with games on the computer, and so on.

Look really closely at that diagram, though.

That is NOT how joysticks work in all of that rich history of mine.

Mind you, for short distances, the behavior of a diagonal push forward (e.g. diagonally to the upper-left) will be almost what I expected -- what I wanted was a diagonal move and what I get is a move forward and and a counterclockwise turn that if I move back to center quickly will do pretty much what I wanted.

Though that move back to center is me compensating for what looks like the chair being a little out if my control, doing something I didn't expect.

Which in a way is unfair of me -- judging the device's behavior based on my own joystick expectations and prejudices.

Now in 4-wheel mode a similar effect happens, but there is also a bit of a "shuffle" that the wheels do at the same time as they turn which makes the behavior feel more like that diagonal move. So I get the illusion of the joystick working more like I expected, and can thus claim that the control is better in 4-wheel mode.

But really both situations are just my prejudices about the joystick and what I think it should be doing, and noticing it fall short.

All of this implies a solution, of course -- just retrain myself on this altered usage if the joystick. And whether this means I

is really up to me and how comfortable I feel with solving such ballistics problems in my head as I am riding along.

I suspect how tired and/or drunk and/or hungover I am might turn out to be crucial variables in that equation, but only time will tell on that one.

In the meantime, I feel a lot smarter about all this today than I did last year. And a lot smarter than those other reviewers who dismissed the iBot's control in standard function and perhaps never had the chance to realize they were wrong.... :-)


Igor Tandetnik on 9 Jul 2009 12:22 AM:

I guess the behavior might make sense if you think of it as driving a car.

The tip of the joystick, when pushed all the way away from straight-up position, describes a circle. Imagine that this circle is a tiny steering wheel, mounted horizontally on a vertical column. When pushed straight forward, it's like holding the wheel with one hand at a 12 o'clock position. To make, say, a left turn in a car, you rotate the wheel left, and then, when the car completes the turn and faces in the right direction, move the wheel back to its original position. Same with the joystick - you move it to a diagonal position, complete the turn, then move back to straight-forward.

Erzengel on 12 Jul 2009 5:15 AM:

I've seen that control scheme used in a computer game before. The X-Axis is bound to rotation instead of movement. It feels very unintuitive though. Usually the X axis allows you to strafe, while another joystick (on relatively modern consoles at least) allows for rotation. It would be awesome if wheelchairs, cars, etc, were capable of strafing like that.

Michael S. Kaplan on 12 Jul 2009 9:34 AM:

Of course putting it all in one joystick is in part to handle the fact that some paraplegics might only have full use of one hand (bad enough that quads can't use the chair since they need to be able to control the joystick)...

But what would strafing look like in wheelchair, exactly? :-)


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