SUMMARY: 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.

This paper deals with a special architecture of Spherical Parallel Manipulators (SPMs) designed to be a haptic device for a medical tele-operation system. This architecture is obtained by replacing the kinematic of one leg of a classical 3-RRR SPM (R for revolute joint). The Forward Kinematic Model (FKM) is particularly addressed to allow the new master device to control the motion of a slave surgical robot. For this purpose, three methods are presented to solve the FKM and compared based on the criterion of time consuming and accuracy. For each method, namely, classic FKM, Improved method and serial FKM, the resolution procedure is detailed and the experimental validation is presented. After comparison, the serial approach involving the use of three sensors located on one leg of the master device is revealed as the most suitable. Experimental validation of the real-time motion control is successfully performed using the serial FKM.

This paper discusses the design of a new spherical parallel manipulator (SPM), which is used as a master device for medical tasks. This device is obtained by changing the kinematics of a classic SPM to eliminate the singularity from the device's useful workspace. The kinematic models of the new device are studied. The geometric parameters of the new device are optimized to eliminate the singularity. A prototype of the new master device is presented. Experiments are carried out using the device which allowed the control of a surgical robot.

This paper deals with a spherical parallel manipulator developed for a master device, used in a teleoperation system for surgical application. The aim is to improve the calculation of the direct kinematic model (DKM) even when the parallel manipulator is in a singular configuration by using an extra sensor for a passive joint. A new simple approach for the DKM calculation of the haptic device, in order to meet requirement of real time applications, is developed. The measure of a passive joint's angle reduces the calculation time and improves the accuracy of the direct model particularly in the vicinity of the singular positions. Experiments were conducted on tele-operation system despite of the presence of singularities in the master workspace. The obtained results demonstrate the feasibility of the approach.