Modeling and instrumentation for position and torque control of a 4DOF force-feedback device

This paper deals with the modeling and instrumentation design for position and torque control of a new designed 4 degrees of freedom (DOF) haptic device to be used in a virtual reality laparoscopic simulator or as an input device for telepresence applications. Low-cost instrumentation is designed for torque/force control using no-contact current sensors and a force sensor. The relations between the applied force/torques and the output voltages are determined by calibration that shows that such low-cost sensors perform just as well as highly accurate sensors. The forward and inverse kinematics models of the 4-DOF are also formulated explicitly by using analytical methods. Based on this models and by introducing the kinematics constraints defined for the parallel part of the device, position control is performed successfully using PD controller. We carried out a PID controller for efficient torque control thanks to the introduced torque sensors. Experimental results that validate and encourage the proposed design are presented.