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Unread 15-07-2006, 12:13
Unsung FIRST Hero
Al Skierkiewicz Al Skierkiewicz is offline
Broadcast Eng/Chief Robot Inspector
AKA: Big Al WFFA 2005
FRC #0111 (WildStang)
Team Role: Engineer
 
Join Date: Jun 2001
Rookie Year: 1996
Location: Wheeling, IL
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Re: Voltage-to-resistance converter for using any joysticks

Jack,
When I am thinking of what takes place (pot to input to A/D to software) I look at what most accurately translates hand motion on the joystick to movement. I am stuck in the mindset of audio and video where the smoothest transitions for audio mixing or video shading take place when the operator has the ability to use the maximum travel over a fixed distance. In the majority of the high end audio consoles fader travel is over 100mm. This translates to the approximate actuating distance of the average human hand/fingers without strain or cramping. Dividing the full range of the A/D (256 steps) over that 100mm gives a step change of 0.39mm/value change. What you do with that range in software is up to the user but I think it gives the max range for accuracy at the A/D. We all know that the cheap pots in any given joystick do not travel the full 100K (+/-50k) so either calibrating the speed controlers or using software to approximate the full travel is essential I know we modify range and acceleration with software for all input regardless of the device that is connected. BTW, I still find teams that do not calibrate controllers in the absence of calibration elsewhere in their system. It must be hard for those drivers to try and compensate for the lack of range in their interface.
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Good Luck All. Learn something new, everyday!
Al
WB9UVJ
www.wildstang.org
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Storming the Tower since 1996.