This season’s robot was a mobile launch platform that was a hybrid between a catapult and a crossbow . A rail, running down the center of the robot guided a wire frame carriage that would cradle the ball to launch it. A chain drive would draw the carriage back, extending two large springs int he process. When the carriage had been drawn back sufficiently, it would be released to launch the ball. The center guide was mounted on a pivot and a winch assembly was used to adjust the launch angle.
To collect balls from the floor, a pair of arms would cradle the ball and pivot it into the launcher.
The team decided that the most important capability for the robot to have, was the ability to catch and shoot the ball. With this in mind, the following objectives were set and prioritized as follows:
- A launch mechanism with adjustable height and power
- A perimeter that allowed us to catch the ball
- Some means of lifting balls from the floor into our launcher
In order to meet the objectives outlined above, we had to adhere to the following parameters:
- A catapult/crossbow hybrid launching mechanism that was light so as not to increase the weight being propelled.
- A pivoting mechanism to tilt the catapult.
- Arms to collect balls from the floor
We had significant challenges to overcome this season. One of our most significant design factors was the size and weight of the ball. The team successfully calculated the necessary angles, velocities and the force required in designing our launcher. We were able to generate the force required by loading springs and generate the force required to extend those springs, storing the energy.
When were able to get a ball into the launcher, it could throw it, quite loudly, as the springs unloaded the energy stored very rapidly.
We chose to use PVC pipe for our ball collection mechanism, however they proved too weak in the heat of competition and we broke them several times before scrambling to rebuild them out of aluminum.
Our launch mechanism, while effective, was loud, and difficult to control and we broke several guide wheels from the sudden release of force, and broke the winch cable for our tilting system making the robot generally unreliable.