CHUTnI: Compensated Holonomic Uneven Terrain Isolator

We present CHUTNI (Compensated Holonomic Uneven Terrain Isolator), an off-road differential-drive with offset turret platform that delivers holonomic control of a stabilized turret on uneven terrain. CHUTNI uses simple drive wheels on a rocker suspension to keep both wheels in contact with the ground, while an actively stabilized gimbal with three degrees of freedom, i.e., roll, pitch, and yaw, holds the turret at a commanded pose with respect to the world frame. The result is lateral, longitudinal, yaw, roll, and pitch motions that can be commanded independently at the turret, with the robot chassis free to absorb the terrain irregularities. We evaluate the physical CHUTNI and also in simulation on test courses and quantify its holonomicity using mobility ellipsoid. Experiments demonstrate holonomic turret motion and arbitrary trajectory execution without stop-to-reorient behavior as seen in robots with non-holonomic bases.