The teleoperation system is composed of two geometrically similar parallel manipulators based on the Modified Gough-Stewart Platform, designed to have uniform force and moment actuating capability at the end-effector (load capacity = 100 N). Each manipulator is controlled by a personal computer PC. Both computers are able to communicate with each other through a bus adaptor. Master and slave force data are transfered to each other by dual port memories (MEMOLINK/Interface). A material of contact object and a tool are steel, the peg and the hole are 20 [mm] in diameter, and the clearance is 10 [µm]. The controller of each parallel manipulator is based on the hybrid position/force controller. The master and slave manipulators are controlled by force which are measured by the 6 axis F/T sensors on the end plate of manipulators. Stability of the system is improved by the proposed control method so called Symmetric Damping Bilateral Control and by smaller lag time in the control loop, since the system has the symmetric structure. Since the forward kinematics is extremely difficult to solve analytically, utilisation of the available sensor redundancy on each manipulator provides a minimum least squared error solution and allows to determine efficiently the position and orientation of the end-effector. The master and slave computers have the same sampling period including force-velocity command conversion, constraint velocity using link interference checking, solution of forward kinematics, Jacobian calculations, solution of inverse kinematics and position servo.
