A High-Voltage Optocoupler-Based Controlled Discharge Method for Improving the Driving Performance of Electrohydraulic Actuators

Electrohydraulic actuators (EHAs) exhibit broad application potential in soft robotics and bio-inspired systems due to their high energy density and structural compliance. However, conventional square-wave high-voltage driving tends to induce charge accumulation, leading to attenuation of actuation amplitude, unstable responses, and degraded repeatability. To address this issue, this paper proposes a driving performance enhancement method based on controlled discharge using high-voltage optocouplers. By connecting high-voltage optocouplers in parallel across the actuator to form a transient discharge pathway and coordinating them with the main driving optocoupler, residual charges are actively released during the charging and switching-off phases, thereby suppressing charge accumulation. This paper presents the working principle and fabrication of the electrohydraulic actuator, as well as the design and implementation of the driving circuit. Comparative experimental results demonstrate that, with the introduction of the controlled discharge mechanism, both the actuation amplitude and cyclic stability of the actuator are significantly improved, providing an effective circuit-level solution for the stable operation of electrohydraulic actuators.