Quote:
Originally Posted by 6600gt
The reason I am going after this is because I want to use the accelerometer for same purpose(get position form it). And if this is true then everything I believed is completely false!
I think you might be forgetting the INERTIA of the robot... It can't physically accelerate that fast!!!
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As I said, this was in perfect conditions. In reality, this isn't possible for a few reasons:
1. The wheel traction won't allow for it. Going through the math, an odd coincidence is that the coefficient of friction between your wheels and the ground is the same as the maximum amount of gs your robot can accelerate at before the wheels slip (assuming your robot has no dead weight and has the same friction on all wheels). This means FIRST robots using skyway wheels can't get above .8gs of acceleration, and the roughtop/wedgetop tread are limited to 1.3 gs.
2. This is an instantaneous acceleration where your robot has not moved yet and your motors are instantly outputing stall torque. Your motors can't output that much torque without ramping up to it first, and applying torque through the wheels will start your robot to move, which means you won't be stalling anymore.
Under very unique (and basically impossible) conditions, I believe these motors could create that much acceleration; however, as I said, I believe that is impossible.
Don't be surprised if you get readings like these from collisions though; collisions are capable of creating accelerations of several 1000s of gs, meaning collisions will still render position sensing invalid much like they do for encoders.
I didn't discover some of these numbers until trying to prove everything again; seeing the new data about what gs are possible with the wheel traction we have, I'm no longer worried about choosing an accelerometer.
Feel free to try the code I developed for position sensing. It took me over a week to develop it working on no other code, and that's alot of valuable time come build season. It does work, better accelerometers are needed for better accuracy is all.