Sunday, May 31, 2009

Update to Keys & Tips for DWB

I added some info to my previous blog entry (Keys & Tips for Dynamic Wheelchair Bowling) but since it's so long, I thought I should post the new info here for anyone who read that previously.

In this blog entry, I elaborate on:



All three of the above topics are long, so I have headers below.

* * * * *


I thought my chair was fixed. It's a little better, but there's still something wrong with my sip-and-puff. It isn't as responsive as it used to be, or should be. My sip-and-puff control system has a difficult time recognizing a hard sip and a hard puff -- which, depending on whether I'm driving forward or in reverse -- those are my braking/stop inputs.

Sip-and-puff users have four different inputs available: hard sip, soft sip, hard puff, and soft puff. For the difference between a sip and a puff, think about drinking a glass of milk with a straw. Take a drink -- that's a sip. A puff would be "blowing milk bubbles" with your straw.

Even when I conscientiously sip or puff as hard as I can (my ability to do so is strong; that isn't the problem) the control unit doesn't immediately recognize the hard sip (or puff). Before it recognizes the sip (or puff) as hard, it first recognizes the sip (or puff) as soft -- and those are turning inputs. So as it "takes time" to recognize the sip (or puff) as hard, it turns me until it recognizes I am trying stop (by giving the correct hard input). Does that make sense?

That explains why I thought my right brake wasn't engaging. Because trying to stop while going forward, my hard sip was initially misinterpreted as a soft sip, which means turn left. So I would turn left for about a second, before stopping, and since I tried to stop with my Bowler aimed at my target, a second-worth of turning left would make me miss the shot by a LOT.

Granted, I have been trying to compensate for this left turn by aiming significantly to the right of my target, but I estimated one second of turning (i.e. soft sip recognition) before stopping (hard sip recognition) and I'm certain sometimes it would recognize the hard sip faster than others (meaning it could turn left anywhere from a half-second, to one and a half seconds, roughly). That means I simply had to get lucky and hope however far right I aimed would match how much left I would get turned before the stop was recognized.

* * * * *


Ben mentioned stopping his chair with his kill switch. Since the kill switch is supposed to immediately stop the chair, I thought I could use it to stop straight (from my earlier thoughts on this, it seemed to work great in Publix). What I found when bowling, was that the kill switch seemed to have a slight delay before it stopped me. Again, from my earlier thoughts on this, you may remember my chair pulls to the right as I go forward. However, that is influenced by the direction of my casters. For example, with my chair pulling right, my casters are going to the right, and if I hit the kill switch, the slight delay would result in my chair "drifting" farther right than I wanted.

However, if I gave a left turn input and got my casters going a little left, and then hit the kill switch, with the short delay, the amount of "right drift" was significantly less than the scenario in the above paragraph. But to execute shots, I often am turning either right or left (slightly either way) as I approach, to get my chair and Bowler in the proper position. So there were times when I would turn slightly left before hitting the kill switch, and my chair would only drift back right slightly before it stopped. Then other times, if I made a slight right turn before hitting the kill switch, it would drift right more than the previous scenario. THAT DROVE ME NUTS! :-)

As you can imagine (if I described that well) I had an extremely difficult time trying to execute shots with any consistency, and of course, I missed many. I think my four scores ranged from like 109-128, and when my sip-and-puff stops me "immediately," my average game is usually about 150 (sometimes, when I'm bowling particularly well, my average can be quite a bit over 150, but there are times my average is under 150 even with a properly functioning chair).

* * * * *


In the previous blog entry, I mentioned I initially setup two drive modes for bowling.

The below link shares roughly what my actual drive settings are.

Note of caution: depending on your motors and driving system, my settings may not be good for you.

I actually think the torque settings (the amount of "power" available for turning) is wrong on the below PDF, because that list was initially setup using my chair's original two-pole motors, not the more powerful four-pole motors that it currently has. The torque settings I think are about half (or even less than half) of the percentages shown in the file.

I think the key is the turning speed. I have my turning speed at only 20% in my bowling mode, whereas it's 35% in Drive 1, which is my safe/indoors mode.

If you aren't sure how to read that table, Drive 2 has my forward speed at 60%, but notice it's "latched type" is three speed. That means I have essentially three "gears" to get up to 60% of my chair's maximum speed. Maximum speed for my chair, I think is six mph. So when I am in Drive 2, one hard puff gets me rolling forward at probably 20% speed and that is essentially first gear (it's like an electronic gear). Another hard puff is essentially second gear and is probably about 40% speed. In order to reach the programmed setting of 60% speed in Drive 2, I have to give another hard puff to put it in third gear.

Now that you know what the three-speed gears are like, I bowl only in first gear. As described above, it's probably about 22% of my chair's maximum speed, but my moderately-paced approach allows me to adjust as I go forward and when my chair is behaving properly, I'm usually pretty accurate.

You might wonder what the alternative to "three speed" latched type is, and for my chair, I believe it's one-speed. That means that whatever speed percentage the Drive mode is set for, the chair will accelerate and reach that speed as fast as possible. This can be fun -- DANGEROUS -- but fun in the right situation. Just for fun, I had my wheelchair guy setup Drive 4 with 100% speed, on one-speed. With the vent on the back of my chair, if I tilted back a little from my most-upright seating position, I can actually pop wheelies and have my two front casters off the ground for about 8-10 feet before they come back down.

I actually don't know if my Drive 4 is still set on the dangerous 100% one-speed setting. It's dangerous because if I get put into Drive 4 and don't realize it, I could easily crash into something -- and that happened once. One time in my bedroom, I guess my nurse kept hitting the toggle switch which turns my chair on, but if it's pulled in the on-direction while it's already on, that advances the Drive mode. So I actually accelerated like a maniac and crashed into my bed. Fortunately I was wearing shoes and there was no damage to my body, chair, or bed.

If you're curious as to why the below file has two tables, the top is my current/previous/old settings. The blank table is so we can make note of any changes to new settings, if I want or need something changed. (Then I can later add the new/current settings to my file; I'll share the Word file if anyone wants to put their name and settings into a file like mine.)

Bill Miller's wheelchair settings (Drive 3 is my bowling mode):

Again, I'll be happy to try answering any questions you may have.


Bill Miller :-)
C1-2 Quadriplegic with a 206 High Bowling Game
Co-founder of Manufacturing Genuine Thrills Inc. d/b/a MGT
My blog:
Business website:
Personal website: