Redesign of robust controllers for rigid-link flexible-joint robotic manipulators actuated with harmonic drive gearing

The authors have redesigned a previously developed robust tracking controller for rigid-link flexible-joint (RLFJ) robot manipulators to handle flexibilities specifically induced by harmonic drive gearing. A more realistic, and consequently more complex model for the torque transmission dynamics which includes frictional losses, kinematic error and nonlinear compliance is utilised. The stability result achieved for the authors´ proposed controller ensures that the link tracking error is `globally uniformly ultimately bounded´ (GUUB), in spite of additive bounded disturbances, parametric uncertainty, and the presence of complex nonnegligible actuator dynamics