Deals with control and performance evaluation of a two degree-of-freedom five-bar haptic interface driven by harmonic DC servomotors. The presented haptic display has nonlinear effects such as friction and motor cogging which affect impedance fidelity. Force feedback control strategies including a feedforward friction compensator based on joint torque and a disturbance observer have been proposed and are evaluated through experiments. The first set of experiments was conducted to measure how well the impedance fidelity could be achieved for various control strategies. The second set of experiments was conducted to investigate the influence of the control strategies on discontinuity perception and to measure the upper limit of the haptic simulation range of the haptic display.

A microsurgical telerobot system has been developed based on the results of the operation task analysis. The telerobot system is composed of a 6-DOF parallel micromanipulator attached to the macro-motion industrial robot and a 6-DOF force-reflecting haptic master device. The master device uses five-bar parallel mechanisms driven by harmonic DC servomotors. The proposed 6-DOF master hand controller has nonlinear coupled dynamics and friction. Since the disturbance force due to friction, gravity and coupled inertia can distort the operator's perception, a disturbance observer is introduced in the operational space and implemented in the microsurgery master hand controller.

A force-reflecting hand controller can provide the kinesthetic information obtained from a slave manipulator to the operator of a telerobotic system. Our goal is to construct a compact hand controller that can provide large workspace and good force-reflecting capability. This paper presents the design and the analysis of a 6-DOF force-reflecting hand controller using fivebar parallel mechanisms. The forward kinematics of the fivebar parallel mechanism has been calculated in real-time using three pin-joint sensors in addition to six actuator position sensors. A force decomposition approach is used to compute the Jacobian. To evaluate the characteristics of the fivebar parallel mechanism, it has been compared with the other three parallel mechanisms in terms of workspace and manipulability measure. The hand controller using the fivebar parallel mechanism has been constructed and tested to verify the feasibility of the design concept and the force reflecting control schemes.

A microsurgical telerobot system has been developed according to the results of the microsurgery task analysis. Several fields of the microsurgery have been investigated and the surgery tasks and tool motions are analyzed to acquire guidelines for specifications of a microsurgical telerobot system. A slave robot system consists of a 6-DOF parallel micromanipulator, that is our own modified Stewart platform type, and a 6-DOF macro-motion industrial robot that mounts the parallel micromanipulator at the end. A 6-DOF force-reflecting master device has also been developed using five-bar parallel mechanisms driven by harmonic DC servomotors. A bilateral control algorithm has been proposed based on the force-position loop, and the local position controller for the master has been developed to minimize the effect of gravity, friction, and inertia.