A Passivity/Lyapunov Approach for the Control of Flexible Joint Manipulators

A passivity and Lyapunov based approach for the control design is presented for the trajectory tracking problem of flexible joint robots. The basic structure of the proposed controller is the sum of a model-based feedforward and a model-independent feedback. Feedforward selection is analyzed and passivity theory is used to design a motor state-based controller in order to input-output stabilize the error system generated by the feedforward. Observability conditions for asymptotic stability are stated and verified, and global convergence is obtained.