On the Design of a Low-Force 5-DOF Force-Feedback Haptic Mechanism

Virtual reality is becoming very important for training medical surgeons in various operations. Interfacing users with a virtual training environment, requires the existence of a properly designed haptic device. This paper presents the design of a new force feedback haptic mechanism with five active degrees of freedom (dof), which is used as part of a training simulator for urological operations. The mechanism consists of a two dof, 5-bar linkage and a three dof spherical joint, designed to present low friction, inertia and mass, to be statically balanced, and have a simple mass matrix. The device is suitable for the accurate application of small forces and moments. All five actuators of the haptic device are base-mounted DC motors and use a force transmission system based on capstan drives, pulleys and miniropes. The paper describes the chosen design, and its kinematics, dynamics, and control algorithm and hardware employed.