Redundantly actuated 3-RRR spherical parallel manipulator used as a haptic device: improving dexterity and eliminating singularity

Abstract

This paper discusses the study of a spherical parallel manipulator (SPM) used as a haptic device for tele-operation applications. The SPM presents poor behavior in singular configurations. Redundancy is used to eliminate the parallel singularity without major changes in the mechanical structure. Comparisons in terms of kinematic and dynamic behavior between the non-redundant and redundant SPM are presented. The results prove the advantage of introducing redundancy in the actuator and sensor to improve the behavior of the SPM. A new control strategy for the redundant SPM is also proposed. The control strategy has been successfully tested and validated on a SimMechanics model.

Forward kinematic model improvement of a spherical parallel manipulator using an extra sensor

“…As described in [14], the inverse Jacobian matrix of the SPM with a redundant sensor located on the joint with Z 3A axis can easily be obtained as follows: with,…”

“…This device reproduces the force feedback to the user's hand. A solution based on actuator redundancy is proposed in [14] to eliminate the effect of the singularity in the haptic control.…”

Analytical Dynamic Analysis of a Kinesthetic Haptic Device

“…; = 1, 2, 3 (15) Virtual work equality by taking into account the gravitational forces of the parallelogram links can be expressed as…”

“…Today, still most of the published designs in the literature are based on Delta structure [13]. Nevertheless, there are other studies that make use of various types of parallel mechanisms to construct their haptic systems [14,15].…”

Optimal design of a new spherical parallel manipulator

“…In a previous work [9], a solution avoiding the singularity problem was proposed. This solution is based on the use of a redundant actuator without changing the design of the SPM.…”