Control of a passively steered rover using 3-D kinematics

This paper describes and evaluates a 3-D kinematic controller for passively-steered rovers. Passively-steered rovers have no steering motors, but rely on differential wheel velocities to change the axle steer angles. This passive steering design is reliable and efficient but more challenging to control than powered steering designs, especially when driving on rough terrain. A controller based on 2-D kinematics fails to accurately maintain the desired trajectory when traversing obstacles. The presented 3-D kinematic controller uses inertial and proprioceptive sensing to modify commanded steer angles and wheel velocities, greatly improving steering accuracy. Validation in simulation and physical experiments is presented. These results are significant because they establish the viability of the passive-steering configuration for precise navigation.