Robotics and Mechanisms Laboratory

Singularity-based Calibration

In this paper a new calibration strategy that does not require any sensors beyond those used to control actuators is applied to the 3-PRS parallel manipulator. Parallel manipulators have several advantages over their serial counterparts, but have seen limited use because of low accuracy, among other reasons. Calibration allows the kinematic model that is used to control the manipulator to be adjusted to more closely replicate the physical manipulator. The architecture and kinematics of the 3-PRS are presented, as well an explanation of this new calibration strategy. The strategy makes use of direct kinematic singularities to obtain the redundant information required for calibration. Implementation of the algorithm is accomplished via a nested series of optimisation problems, each one accomplishing a simpler stage of the overall procedure. A simulated calibration is performed, and the algorithm successfully returns the exact values used to generate the test data.