Control of port Hamiltonian systems by dissipative devices and its application to improve the semi-active suspension behaviour

The port Hamiltonian framework is a powerful tool for modeling a wide class of nonlinear systems such as robots and, more generally, mechatronic systems. A wide variety of mechatronic systems are controlled by operating dissipative components and the standard approaches for the control of port Hamiltonian systems are not applicable. Facing the limitation that the controlled devices can only dissipate power, the issue is to find a proper control law to satisfy the control requirements. This paper proposes to choose the control inputs to lead the input power of a subsystem in oder to satisfy the requirements by controlling the energy stored or the power dissipated in that subsystem. A slight extension of the definition of port Hamiltonian system is proposed to allow the description of a larger set of mechatronic systems. Although some important issues remain open, the example of the semi-active suspension shows that some positive results can be achieved by applying the proposed approach. Copyright © 2006 IFAC.