Design Process - WG

We decided early on to use plywood to construct our mechanism. This decision was due to our easy access to wood and a laser cutter to create the unique profiles. We also used wooden dowels as our shafts. 

To design the cam profile, we used a circle with an offset from the center. This resulted in a sinusoidal motion. The waves are the follower in the system and we wanted them to fully capture the cam. This results in horizontal and vertical movement. This allowed us to mount our paddleboarder to one of the waves and it would move back and forth and up and down. This was important in our design because we wanted it to mimic the true motion of waves. 

In order to attach the back of the wave, we had to accommodate for the vertical and horizontal motion. To do this, we used a slot in the back of the wave plate that would have a fixed shaft as its pin. The shaft is stationary and it allows each of the waves to individually move along its slot and follow the cam profile.

Solidworks Wave Animation.mp4

To mount the paddleboarder, we wanted it to look like he was resting on the top of the waves and moving with them. We could not mount the board directly on a single wave because each of the waves have a different position at any given moment and would provide interference to the board. We decided to change the wave profile of the center wave to have a lower connection bar. Then we mounted the board higher than the waves so it would always be above the waves. To allow the board to have fluid movement above the waves and rest on the waves that are at their peak, we used a 3D printed ball joint that we fixed to the center wave. The ball joint was then mounted to the bottom of the paddleboard. 

To motorize the mechanism, we used a 360° continuous servo connected to the camshaft through a gear train. The output rpm of the servo was slow enough that we didn’t need to gear it down. This made it a lot simpler to design and machine since we created a gear train with a series of the same size gear. To make it as simple and cheap as possible, we downloaded a gear profile for a 40T spur gear and cut the profile out of ⅛” acrylic on the laser cutter. Even though we didn’t need to gear down the speed, we wanted to locate the servo at the back of the mechanism rather than the front. We also originally wanted to include another shaft with rotating fish that would be connected to the gear train. However we were not able to include it in our final prototype.