Analysis, development, and control of multi-degree-of-freedom passive haptic devices

Abstract

Stability and transparency are key design requirements in haptic devices. Replacing conventional electric motors with passive actuators such as brakes or dampers can improve both stability and transparency as passive actuators can display a wide range of impedance while guaranteeing stability. However, passive haptic devices suffer from a serious drawback; their force output is difficult to control. This issue was addressed extensively for planar manipulators but devices with higher degrees-of-freedom (DOF) have not been examined. This thesis proposes a generalized framework for analyzing and controlling higher-DOF devices and examining the effects of the kinematic structure on the force output capability. A first of its kind 3-Degree-of-Freedom (DOF) parallel passive haptic device was developed along with a novel controller designed specifically for the 3-DOF passive device. This thesis also investigates the use of a nonlinear disturbance observer to aid in the control of passive haptic devices.