Modeling and control of an improved dissipative passive haptic display

Abstract

This work investigates the modeling and control of a new dissipative passive haptic display that uses magnetorheological (MR) brakes as actuators. The device is energetically passive, meaning that it can only remove energy from the system. All motive force must be generated by the user, which guarantees stability of the system and safety of the human operator. A first order system approach is presented as a tool for modeling MR fluid behavior in a low-speed braking device. A simulation was developed that uses the brake model and the equations of motion to predict robot motion based on force input and actuator commands. The accuracy of these models was demonstrated with comparisons to experimental data. Two forms of path following velocity control were successfully implemented and shown to significantly reduce path error in preliminary experiments with human operators.