Thread: How do you aim your shooter?
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Unread 02-02-2006, 16:06
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Jared Russell Jared Russell is offline
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FRC #0254 (The Cheesy Poofs), FRC #0341 (Miss Daisy)
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Re: How do you aim your shooter?
Quote:
Originally Posted by DjAlamose
I don't know where you got this from but good luck then.

We have our robot fully automated for just about everything. All you need are the equations for speed, angle, height, and distance. Once you have those the RC can control the robot fully based on where it is. In reality you dont need the camera if your robot can keep track of where it is on the field at all times (much easier to use cmucam).

But we plan on haveing 3 different modes for our shooter, fire, off, and store. Can't give details other than 270 degrees, 4 balls per second, and 2 shooting angles. Pneumatics and window motors will be used for aiming the shooter as well as the small cim motors which will provide the speed for throwing the ball, vary that and you can send the ball just about anywhere.
Finding a reliable ball kinematics equation that takes into account spin and air resistance is VERY hard to do on the RC (but not impossible). And that's not even taking into account the trig needed for angle adjustments and converting the x and y coordinates of the target seen by the camera to angles. Try doing the math yourself - in order to get a full-fidelity representation of what your camera sees, you not only need to convert between pixel offset and angle (which is fairly easy), but also take into account that the 2D space represented by the camera's data feedback is in actuality a representation of 3D space. To combine all of these factors together, you have to use some matrix math.

It is MUCH simpler to use look-up tables, and in addition they are always going to be faster. They do all the dirty work of physics for you.

Our team's solution is to slave camera pan to the turret (turret rotation controlled by a feedback loop) and use a constant camera tilt. Then, a look up table for flywheel speed is indexed by the y pixel offset of the target. With the right choice of camera tilt angle and lens, you can see the goal from pretty much anywhere that you could realistically shoot from. It really doesn't get much simpler than that.