“Rotary vehicle” that moves with three degrees of freedom

This paper proposes a new control method of a land vehicle with at least two steer-drive wheels. We call this vehicle a “rotary vehicle”. By analyzing a general three degrees of freedom motion Q, an algorithm for computing each wheel´s driving speed and steering angle is presented. Through this method, we can superimpose an arbitrary rotation on an arbitrary translational motion. When we know the current wheel steering angles and incremental movements of all the wheels on a rotary vehicle in the last sampling time, computing an estimated incremental motion is a non-trivial problem, because all the wheel axes may not meet at one point. An explicit algorithm to find the incremental motion (odometry) is also presented in this paper. The first version of a rotary vehicle called “Shepherd” is being constructed at the Naval Postgraduate School. This vehicle is going to be applied for the mine/unexploded-ordnance clearing mission