by LROBBINS » 27 Apr 2015, 22:43
To adjust the joystick response, you will have to find someone with the Dynamic software, computer dongle (a gadget that plugs into a PC and contains the license for using the software) and a programming cable. The dongles come in different "flavors", the most common, a dealer level dongle, doesn't let one adjust everything, the harder-to-get OEM level dongle lets you adjust everything. There are quite a few parameters that affect joystick response, but usually a slow response (reduced turn acceleration and deceleration) leads to worse control - the chair will not start to turn when you move the stick, and will continue to turn after you center the stick. Banging into doorways is the common result.
More precise control is achieved if you set turn acceleration and deceleration as high as possible, but set turn rate way down - this will give slower turns, but better response. You may also want to turn down speeds as well until you get used to things, or if your controller has a speed pot turn it way down. There are other, less important, settings that are sometimes pretty useful - tremor damping if your hand isn't steady, deadband so nothing happens until the stick is moved some distance from center, and others. A very important one is motor compensation, but you should only adjust that after your really understand what it does and why it has to be adjusted in very small steps - if it's too little, the chair can be very sluggish, if too much the chair can be very jittery, and if really too much the chair can run away and be COMPLETELY uncontrollable. Adjusting that needs a lot of caution.
I strongly recommend that you download all of the manuals for the Shark from the Dynamic web site - you will have to register as some kind of professional (but no one checks on your credentials). Once you've done that you can get all of the installation, operation, programming and user manuals. I have only worked with Dynamic DX controllers and not the Shark so I can't be any more specific, but the manuals are quite detailed. One or more of them will contain a list, with descriptions, of all of the programming parameters. Warning though, the explanations are sometimes less than crystal clear (at least if the Shark manuals are like the DX manuals that I'm actually familiar with). Burgerman has a good walk through of programming on the main WheelchairDriver pages - it refers the the parameters used in P&G controllers, so they're not exactly the same as on Dynamic controllers, but not all that different either.
If you don't feel up to doing that yourself, you will have to find someone to help you with this, but re-programming the controller really can make a world of difference.
I'm glad that you say you rest your arm on something solid. One of the things that often leads to poor control is trying to move the stick with your hand not supported. If you do that, every little bump will make the stick move. I like to rest the heel of my hand on the joystick housing and use index and middle finger on one side of the stick and thumb on the other and usually make very small movements. Steering a chair is very different from steering a car - it's much more like using a joystick for computer games. You are not pointing the joystick where you want to go. You're not commanding "where" you want to turn to, but how fast you want to be turning and the chair really needs to be programmed so that when you command x turn rate for y time it then gets you to z angle. At that point you center the stick and the turning should stop right then and there. Most chairs out of the factory are not programmed that way.
Consider posting on the Everything Powerchair part of this forum and asking if there's anyone in your area who could help you with programming the Shark, or could point you toward a tech who actually knows how to do this - rather few do. It might also help to put your location in your "profile" (look for a button that, I think, says "User control panel").
Ciao,
Lenny