Model based landing control for a bistable electromagnetic actuator with discontinuous dynamics

A design approach is presented to address the soft landing problem for electromagnetic actuators with discontinuous dynamics. The approach uses finite-element-analysis to generate the static functions that make up the dynamic model, as opposed to traditional methods of deriving/fitting an analytical model of the system. The mappings are then implemented as look-up-tables to form a feedback controller. The actuator is also challenging for control: it is bistable due to the presence of a permanent magnet for holding, and consists of multiple springs that are active at different regions of operation, creating discontinuities in the dynamics. The discontinuous dynamics are handled by designing a corresponding discontinuous trajectory in state space and feed-forward control signals, thereby avoiding undesired transients when switching between the springs. Simulation results are presented showing the robustness of the controller in the presence of model perturbations and measurement noise, as well as successfully crossing the dynamic discontinuity without transients.