AutoTurret
Here comes my first project using the Mindstorms NXT kit... I started off with building a slingshot-type device that could automatically fire a ball using a rubber band and one of the servo motors in the Mindstorms kit. Once I was finished, though, I decided that having a rotating base and a possibility to move the robot's "head" up and down would be nice. So, after about three days of constant re-designing of about every component of the robot (first, the base was not stable enough for rapid movement, then I realized that the slingshot triggering mechanism could not handle rubber bands with a lot of tension on them and that it tended to jam, and so on), I came up with this - see the video on the right.
If everything goes well, the slingshot device is able to shoot the ball about 3-4m which is more than enough for this first experiment provided that the ultrasonic sensor used for activation is only accurate to less than one meter. A thing that I would have loved to add (but have no idea how to do it) would be an automatic re-loading mechanism for the rubber band as I found the motors to be quite strong, but that might be a thing to do in another experiment...
Software
AutoTurret's (fairly simple) software was written in NXC and ran on the default Mindstorms Firmware. See the
source code. Is there any other way to make one of the servo motors simply hold its position even though there are forces pushing against it than using RotateMotor with a quickly alternating series of +1 degrees, -1 degrees, etc.?
