How to Build the Bumpers

•  Attach rodjoints to purple tube on both sides of tube
•  Attach lighthouses to rodjoints
•  Attach lighthouses to yellow arm with a perpendicular grey joint
•  Attach black arms to yellow arms with minirod and black joint to create side bumpers
• Attach the 1x12 customized black rod piece on one edge of a 2x8 grey plate. The black rod piece should be fitted with the switches that have been wired with the resistors. Make sure the wires lead away from
• In the middle of this grey plate in front of the black rod, attach the two green tiles.
• Place minirods in the ends of the yellow arms. Place minirods through the holes in 2x8 grey plate, one on either side of the green tiles. Make sure the  small knobs of the grey plate are facing upwards towards the yellow arms. 
•  You may need to enlarge the holes in the black rod a bit so that the sensors arms swing freely.  If the holes are too small, the sensor arms will not spring back into the open position, thus continuously activating the sensor.
• Place another grey plate, face up over the other end of the minirods.

The two front switches and the two back switches are all spliced together with a Lego input block. This block can then be attached to the sensor input on the brick.  Because each switch carries a different amount of charge, due to the varied resistors they contain, the sensor input can now registor which switch has been hit.

To customize our parts, we used a milling machine to cut the holes we needed. The machine was run using a computer program in G-Code .