Machine Description

The Cleansweep 7 machine concept is a robot intended to lower an arm into the slot, and then use this arm to push and lift the ping-pong balls into the opponent’s side of the arena. In order to achieve this functionality the robot consists of a chassis, driven by a dual gearbox, an arm that is moved via a rack and pinion mechanism, and a “finger” which is driven via a pulley located within the arm. The arm is raised and lowered by a lift system that constrains the arm via slots “pins” made of 2 blocks of PVC. Aluminum plates bolted to the PVC helped to keep the arm from deforming and popping off the plates. Ball bearings were used to support the axle that housed the pinion gear, due the high loads placed on the axle. All the mechanical elements performed as expected at the point of the competition.

Alterations to the original design included the aluminum plates bolted to the PVC, The method of fixing gears to the shafts, and the coupling of the dual gearbox motors to their drive axles. The aluminum plates were added to the design after it was realized that the arm, although already supported, could deform enough to pop off the constraining pins. The plates not only prevented this from happening, but minimized jamming, reducing the coefficient of friction and significantly improving the performance of the machine. The gears were intended to be glued to the shaft after viewing other teams design, but it was clear that the epoxy could not support the torques that would be applied to it due to its poor strength under a shear stress. Set screws were then used. Although many other teams used inflexible couplings due to their simplicity, we later opted to use flexible couplings because they followed better engineering principles. This required small changes from the original design.

Our machine was able to utilize an unexpected quality to great effect, and this quality was discovered during the testing of our machine in the arena. The elasticity of the pulley belt created a spring like effect and allowed our machine to toss balls in a trajectory that most teams could not block or achieve. This quality was also very exciting and drew a lot of cheers from the crowd during the competition! However we were unable to defeat our first opponent despite the valiant efforts of our machine and its driver Travis in battle.

Here are some pictures of the completed machine: