Singularity-free algorithms and design scheme for a new 6-DOF parallel haptic device

It is known that parallel-type mechanisms have more singularities than serial-type mechanisms. In haptic application, these singularities deteriorate the system performance generating reflecting force. Moreover, different from general manipulators, haptic systems can´t avoid the singular point, because they are operated by user random command. Although many singularity-free algorithms for serial mechanisms have been proposed and studied, singularity-free algorithms for parallel haptic application have not been deeply discussed. In this paper various singularity-free algorithms, which are appropriate to parallel haptic system, will be discussed. Furthermore, to overcome singularity problems, a new design including redundant actuation is proposed. The proposed mechanism has fairly large workspace and is relatively light by employing non-floating actuators.