Shear force feedback control of flexible robot arms

For flexible robots with rotational joints it has been shown previously, by the first author, that direct strain feedback can damp out vibrations very satisfactorily. In this paper, a simple sensor-based output feedback control law, called shear force feedback, is newly proposed to control vibrations arising from structural flexibility of robots of Cartesian or SCARA types. Closed-loop exponential stability of such shear force feedback system is proved. Experimental results on set point control and trajectory tracking control are reported. It is found that the simple PI + shear force feedback can yield good performance for both robot motion and vibration suppression.