Design Challenges

We faced three main challenges when constructing this sculpture: connecting a Lego motor to the chaos kit tracks, aligning the arm to the ramp, and positioning a touch sensor for 'zeroing' the motor.

The Lego motor did not have very many parts that could match with the chaos kit parts, meaning we had to use a mixture of Lego parts, chaos kit parts, and a lot of tape. In the end, we were able to mount the motor onto a small pipe that could connect to the ramp. 

For the ramp and arm, the hard part was aligning the rotation point of the arm with the end of the ramp. Since the arm had to be mounted onto the motor, it had to be longer than needed so it would balance on the motor meaning that the rotation point was harder to find. In the end, we decided to use paper and tape to create a 'V' shape that the ball could bounce off of as a safety incase it couldn't hit the arm.

For the motor encoder to become zero at the same point every time the code was run, we decided to use a touch sensor to let the motor know it had reached the zero point for the encoder. The problem was that the touch sensor required a hard and flat surface to record the press of the button, and that this surface was hard to mount at the right angle. We overcame this by mounting the sensor on the motor instead, and used tape and chaos kit parts to mount a flat surface on the frame of the sculpture.

A challenge we faced when programming was that we wanted to use the built-in PID system for smoothly turning the motor to a specific angle, but were unable to get it working reliably. We eventually decided to write custom code to replace it, which works perfectly. 

Results

This is a side-by-side comparison of our WM2D simulation of the structure and the real life structure.

Apart from the ramp and color sensor, our WM2D model is a birds-eye view of our mini-sculpture.