Path tracking of parallel manipulators in the presence of singularities

Parallel manipulators are uncontrollable at singularities due to the unfeasibly high actuator forces required. Existing remedies for singularities generally focus on actuation redundancy and singularity avoidance. While actuation redundancy increases cost and design complexity, singularity avoidance reduces the effective workspace of a parallel manipulator.; This thesis presents a path tracking type of approach to operate parallel manipulators in the presence of singularities. We study motion feasibility in the singular neighbourhood and conclude that a parallel manipulator may track a singular path if its velocity and acceleration are properly constrained. Techniques for path verification and tracking are presented, and a modified control method that takes actuator bounds into account is examined. Simulation results are given to demonstrate the usefulness of this approach.