Energy saving by extremum-seeking control using an Actuator with Adjustable Stiffness (AwAS)

In repetitive motions, Actuator with Adjustable Stiffness (AwAS) can realize resonance and largely reduce energy consumption thanks to its ability to change the level of stiffness and adjust its natural frequency to the desired motion´s frequency. In conventional method, an ideal stiffness value is calculated from frequency of the target motion and parameters of AwAS beforehand. This is an off-line system. Extremum-seeking control allows AwAS to optimize its stiffness on-line. Therefore, even if the frequency of the desired motion or parameters of AwAS change in unexpected time, it can optimize the stiffness and realize energy saving continuously. It was confirmed by numerical simulations.