Projectile Motion

[commonsense]

Hey does anyone have a good algorithm for finding the velocity needed for the ball to go a certain distance and height. We have been working on it, but it has been pretty drab, and one of our programmers walked out on us because of it (of course he was pretty tired and needed food.) Or if you already have it programmed in LABview that's what we are using. This would be amazing cause it has been really nerve racking to try and do the physics (it's been months since I have had to do this work.) Thanks

[Jon Stratis]

Doing the math can certainly help (and is very educational)... but personally, I would rather set it up with trial and error. Get your robot set up so you can easily change the shooter speed (using a potentiometer on the OI, for example), and feed in balls until you find the right speed for a given distance. Do this for several different distances, plot the results, and find a line of best fit (linear, quadratic, whatever gives the best results).

[RyanCahoon]

Do this for several different distances, plot the results, and find a line of best fit (linear, quadratic, whatever gives the best results).

Or discretize your parameters and use a lookup table (optionally add interpolation to this to get a piecewise model).

[dbeckwith]

Yeah trying to figure it out yourself is probably way too hard. I don't think you necessarily have to come up with a model by trial and error though (even though that might be conceptually the simplest solution). You could probably find many models online that are very accurate (i.e. they incorporate drag, backspin and frontspin, and other factors). I think there might even be some that were created specifically for FRC, and are modeled off the balls we are using. With the material and weight of these balls, a simple parabolic motion model is definitely not going to be accurate.