This 6-wheeled robot has 4-wheel steering that allows for very tight turns. The remote control program allows you to steer at any angle from 0 degrees (going straight) all the way up to 90 degrees, which pivots the robot directly in place.
In addition to controlling the steering, the program also calculates the correct speeds for the two center drive wheels to match the steering angle. Getting these calculations right required a little trigonometry, a little geometry, and a little algebra. See the Steering Geometry diagram below if you want to see how it was done.
For other ways to steer with 4 wheels on a 6-wheeled rover, see the Mars 2020 Rover.