Videos

Marty: The Performance Art Robot

The version of Marty in the following video, was programmed to allow one to enter values for vehicle distance in centimeters, and vehicle spin in degrees. This made it possible to plot the lengths and angles of the shapes on paper with a simple measuring stick and protractor.
The following image reveals the formula used to calculate the motor axle duration, from a request to spin the vehicle 120 degrees.

Circumference of a 360 degree spin ( the red circle)
Circumference = 3.14 x diameter = 3.14 x 11.9cm = 37.37 cm
So for a 120 degree spin the vehicle wheels will need to rotate 12.46 cm ( 37.37 / 3 ).