Passive and active constant force-displacement characteristics and optimization of a long-stroke linear actuator

In applications such as vibration isolation, gravity compensation, pick and place machines, etc., the applicability of commercial low force passive devices is limited and hence would benefit from an improved and preferably variable force level. This paper presents and investigates such a long stroke constant-force versus displacement actuator topology, where analytical and equivalent circuit models are detailed and compared with comprehensive three dimensional (3D) finite element analyses. Furthermore, the optimization of such an actuator by means of aggressive output space mapping is considered. This technique employs a combination of a single analytical equation and a 3D finite element model. Specifically, the optimization is applied to obtain a passive and active force level of 200 N and 300 N, respectively, where the force- displacement response is constant over 60% to 90% of the total stroke.