Our group has adopted a catapult design throwing arm. We originally had two inch pvc tubes for the throwing arm combined with bungy cords to provide the necessary tension to launch a tennis ball. The bungy cord provided more than enough force using a pully (we may replace the bungy cords with surgical tubing), we were able to lower the friction on the bungy cord and increase energy to throw the ball. Our design is aproximately two and a half feet tall and two feet wide. As of now the design is too heavy and the throwing arm is too long. In the future design, we plan to implement a shorter throwing arm. Additionally, we plan to implement a reloading mechanism and develop a hooking mechanism to latch the throwing arm. One last item we plan to implement is the ball release mechanism.
Items that we have not developed yet is the logic system with sensors and the recocking of the throwing arm.