Design of a novel 3-DOF parallel-type haptic device with redundant actuation (ICCAS 2007)

In this paper, a novel 3-DOF parallel-type haptic device with one redundant actuator is presented. The haptic device has a similar kinematic structure with the well-known Delta manipulator. However, it has the special arrangement of actuators and one redundant actuator to increase the workspace with high stiffness. Specifically, the axes of two rotary actuators are placed on the same line and the axis of the third rotary actuator is perpendicular to the line. The redundant actuator rotates the third actuator and the corresponding leg about the line. With the special arrangement of the actuators and the employment of the redundant actuator, the total workspace can be greatly enlarged. The control methodology for the redundant actuator is suggested, which maximizes the stiffness of the manipulator. The kinematic and stiffness analyses have been performed. The design optimization to maximize the stiffness in the prescribed workspace is presented. Finally, a prototype haptic device has been developed.