In this paper. an optimal PID controller is introduced for an antagonistic variable stiffness actuator (AVSA) based on Hammerstein models. A set of Hammerstein models is developed for the AVSA using the voltage difference method. For each stiffness level. https://www.bekindtopets.com/mega-save-NHL-Florida-Panthers-Frozen-iPhone-13-Pro-MagSafe-Case-p93068-save-extra/