Abstract-Semi active devices to modify the stiffness or the damping of systems received significant attention in the recent years. In this paper, two solutions of a variable compliance device to change the physiotherapists feeling of the thorax compliance of a 6-month old infant torso training simulator are presented. A first solution, using a variable orifice device which allows to change the compliance by changing the radius of a flow pipe is proposed. Another solution is to use a magnetorheological fluid damper. Both systems are presented in detail and discussed especially for their applicability to be integrated in the simulator.

Semi-active energy dissipation devices are used in various domains like the automotive industry or seismic protection structures. This article presents the design and the implementation of a cylinder/piston energy dissipation system in a 6-month old infant simulator for respiratory physiotherapy training. The system is supposed to modify the compliance of the simulators thorax by equipping it with a flow changing device connected between the two cylinder chambers. The principle consists in modifying the geometry of the flow pipe section. For that purpose, two solutions are proposed and implemented.