Dynamically optimal trajectories for earthmoving excavators

Abstract We consider the problem of generating time-efficient, minimum torque motions for earthmoving excavators. Limits on actuator forces, as well as on joint velocities and accelerations, are assumed given, and the objective is to produce the fastest possible minimum torque motions while avoiding torque saturation limits. Relying on a set of recursive geometric algorithms for calculating the excavator dynamics that also calculates analytic gradients and Hessians of the dynamics as a by-product, we develop robust, reliable algorithms that generate such optimal trajectories. The resulting trajectories are compared with actual digging motions of experienced operators.