28 October 2012
Google's self-driving cars are an increasingly common sight around Mountain View. The spinning LIDAR[?] sensor on the roof makes them quite distinctive. Engineers take the fleet out every morning to test new hardware and software on the local roads.
Last Halloween I dressed up as Google Street View. This Halloween I went as a self-driving engineer. It was a fun and easy costume to make. The key was creating a convincing spinning LIDAR sensor. It was made with a soda can, a plastic cup, a CD, and a small motor.
First, find some scissors you no longer love, and cut the top and bottom off the can. Discard the top, but keep the bottom for later. Then cut the rectangle of aluminum into an arc that can wrap neatly around the slightly tapered cup.
Turn the aluminum inside out, wrap it around the the cup, using clear tape to secure it in place. Add a strip of black electrical tape to represent the lenses of the LIDAR. In operation it will be rotating so fast that all one will be able to see is a blur. Next, cut the bottom off the cup.
Expand the hole of the CD so that its inner diameter can fit around the motor with about a millimeter of play on each side. Then cut the CD so that its outer diameter matches the bottom of the cup. Hot-melt glue the CD to the cup. This forms the lower bearing of the LIDAR.
The upper bearing of the LIDAR is made from what was the bottom of the can. Drill a hole in the middle for the motor's shaft. Trim down the diameter of the can so that it fits snugly part-way down the cup. Glue the can to the cup, and glue the shaft to the can.
Moving on to the helmet and mounting rig. This requires a hardhat, a strip of wood, a couple of nuts and bolts, and two 30 cm long lengths of 1/4 inch copper tube.
Bend the pipe to fit over the hard hat. One might try using a soup can to get the radius consistent. Flatten out both ends, and drill a vertical hole in the middle. Corresponding holes are needed in the wood.
Assemble the mount, and paint white with a couple of coats.
Finally, either glue or bolt the mount to the hardhat. Glue the motor to the middle of the wood. Attach a couple of D-sized batteries to the inside of the hardhat, running a couple of wires out the back, to a switch, then to the motor. The costume is now complete.
I made four copies of the costume. The resulting fleet of self-driving engineers was quite a hit at Google's internal Halloween party (Googleween).
The highlight of the event was when we were endorsed by 'Mitt Romney' (with his binder of women). At the end of the evening we presented one of the LIDAR helmets to the self-driving car team as a souvenir.