Damping enhancement of haptic devices by using velocities from accelerometers and encoders

High-stiffness environment emulation requires a haptic device to have a large damping coefficient in order to keep the stability during a virtual contact. Aimed at increasing the maximum allowable damping coefficient, two new approaches of using a velocity derived from both acceleration and position measurements are presented in this paper. An adaptive mechanism is provided to accommodate both offset and gain uncertainties of the accelerometer. The feasibility of using the velocity derived from both accelerometer and encoder is demonstrated experimentally when a one-degree of freedom (DOF) haptic device contacts with a virtual wall. The contribution of this paper suggests that any existing haptic device would be able to expand its capacity of emulating high-stiffness virtual environments when velocities estimated from both accelerometers and encoders are used.