The aim of the project was to make a robot that can pick-up upto 2 ping-pong balls from the ground and shoot them such that it lands on a point 3m away with a margin of error of 3 cms. The robot was supposed to participate in IIT Bombay’s Techfest in 2015.
The arm of the robot was made using corrugated plastic sheet and was controlled by a servo motor using a microcontroller. The manipulator(gripper) comprised of a PVC tube with a servo shutting a cap such that the ball is forced into the tube. The mechanism could load 2 balls at once and store them for later use.
The shooting mechanism was made of another PVC tube with a motor at each end. The motor on the bottom end had a crank mechanism attached to it in order to push the ball into the throwing mechanism. The motor on the top-end was the main component of the shooting mechanism. It had a rubber wheel attached to it which would spin and impart momentum to the ball by pushing on it very hard.
The control was done through a wearable glove with two flex sensors and an accelerometer. The operator could switch modes by bending the fingers which had flex sensors. The combination of two fingers could trigger 2^2 modes on the robot.
Mode-1 (One finger pinched) : Tilting the hand left and right operated the loading cap. Tilting the hand up and down changed the angle of the arm itself.
Mode-2 (Two fingers pinched) : Tilting the hand forward or backward would move the robot forward or backward. Tilting left and right controlled CW and CCW rotations about its axis respectively.
Mode-3 (Other finger pinched) : Shooting mode triggered a pre-programmed sequence of actions of loading the ball into the shooting tube and then moving the crank for loading. The wheel starts spinning as soon as the mode is executed and picks enough momentum before the crank shaft shoves the ball into the space between the tube and the wheel.