Planning longest pitch trajectories for compliant serial manipulators

Abstract

Our work addresses the problem of planning an optimal pitching trajectory for compliant serial manipulators. We propose a generic framework for finding the longest possible pitch given angle, velocity, and torque constraints. Within this framework we can decompose an original infinite-dimensional task to finite number of similar steps. As a result, the implemented procedure gives an optimal release configuration, temporal control torque profiles satisfying dynamic constraints, and optimal stiffness coefficients for compliant joints. Computational complexity of the nonlinear optimization task was reduced applying a novel motion parametrization method. The proposed method was illustrated for a particular example and experimentally verified with the KUKA LWR4+ arm.