Five-bar linkage haptic device with DC motors and MR brakes

This paper presents the design and implementation of a five-bar linkage haptic device with DC motors and MR brakes. To apply MR brakes to the 2-DOF haptic device, its kinematic requirement is described by Jacobian analysis. Through the analysis, MR brakes can be used to display the damping force in a multi-DOF haptic device when it has the orthogonal Jacobian such as Cartesian manipulator. The proposed haptic device has a backlashless cable transmission linking the DC motors and MR brakes in parallel. The quasi-quantitative Z-width for performance evaluation illustrates the displayable force range of the haptic device. Results indicate that the collaboration of DC motors and MR brakes has the broader Z-width than that of the single use of DC motors. The control method based on the power flow for the force display is applied to the proposed haptic device. Results show that this control method can provide the realistic force display with stability to the proposed haptic device. The conclusions indicate that the haptic device with DC motors and MR brakes can be used interchangeably in all multi-DOF haptic applications, and further studies must be done to find the quantitative performance measure and to improve the suggested control method.