A Review on the Dynamic Control of Parallel Kinematic Machines: Theory and Experiments

In this article, we review the dynamic control of parallel kinematic machines. It is shown that the classical control strategies from serial robotics generally used for parallel kinematic machine have to be rethought. Indeed, it is first shown that the joint space control is not relevant for these mechanisms for several reasons such as mechanical behavior or computational efficiency. Consequently, Cartesian space control should be preferred over joint space control. Nevertheless, some modifications to the well-known Cartesian space control strategies of serial robotics are proposed to make them perfectly suited to parallel kinematic machines, particularly a solution using an exteroceptive measure of the end-effector pose. The expected improvement in terms of accuracy, stability and robustness are discussed. A comparison between the main presented strategies is finally performed both in simulation and experiments.