Nonlinear disturbance compensation for haptic device

The Sensor Glove II (The SG II) is a glove type haptic device. The SG II supports 20 degrees of freedom which corresponds to the total DOF of the human hand. It can measure the force and the angle of each joint and feedback the force from the manipulated environment in each joint. The motors move pulleys of the device through wires in tubes. The nonlinear friction causes disturbances and difficulties in the control. This paper proposes a control method with disturbance compensation based on a sliding mode observer for SG II. If the system is held on a sliding surface, the system is robust against certain parameter changes and certain nonlinearity. The sliding mode observer is an efficient scheme for compensating nonlinear disturbance. The results of free motion experiments show good performances