Fig. 2: Characterizations of arc discharge, vibration, and recovery in the AH actuator and robot.

A Simulated spatial temperature distribution during electrode discharge, calculated using COMSOL 6.0 with an electrode distance of 1.2 mm and a voltage of 6500 V. B Thermal infrared imaging of the actuator during operation, maintaining the same electrode distance and voltage as the simulation. The core temperature of the AH actuator reached 548 K, as measured using an infrared thermometer (FLUKE TIS60+). C Plot of experimental data on the relative amplitude of the actuator at different electrode distances and voltages. D Comparison of theoretical (thick dashed line) and experimental (thin gray line) results for actuator output displacement, with the thick solid line representing the average across multiple experiments. E Optical images capturing the robot’s crawling and forward movement (∆x) during one driving cycle, with operating conditions of 6500 V and a pulse width of 200 ns. F Sequence of recovery processes post-damage due to external force (F) during motion: initial velocity (v₁), post-recovery velocity (v₂), and recovery time (∆t). Includes optical images of the actuator recovering in 1.75 s after being crushed by a force equivalent to 20,000 times its weight (200 g). G Continued robot performance post-recovery from damage induced by a force 50,000 times its weight (500 g). H Recovery time as a function of input pulse frequency and width after a 500 g weight damages the robot. No recovery was observed at 50 Hz–100 ns input parameters, all tested at a voltage of 6500 V. The error bars indicate the standard deviation of three trials. I Recovery time and speed decay ratio post-damaged by varying weights (50 g, 500 g, 50 kg). The speed decay ratio is defined as the post-recovery speed relative to the pre-damage speed, measuring at a constant voltage of 6500 V. The error bars indicate the standard deviation of three trials.