On the regulation of the energy of elastic joint robots: Excitation and damping of oscillations

The paper presents a new control law for elastic joint robots that allows to regulate the energy stored in the system to a desired value. Being able to either remove energy from the system or inject it, oscillations can be both damped out and induced. Therefore the control law can be used for asymptotic regulation to a desired configuration and (in case of additional constraints) generation of asymptotically stable limit cycles. Compared to other methods, we can formally guarantee the previous property keeping at the same time the control law simple and easy to implement. Furthermore, using the energy stored by the intrinsic elastic elements in the joints, high energy efficiency is achieved. Simulations and experiments are also provided, in order to further validate the theoretical results.