Pulse-width-modulated charging of ionic and capacitive actuators

We report on using a pulse-width-modulated (PWM) signal for driving the ionic electroactive polymer (IEAP) actuators. The traditional approach for driving the IEAP actuators involves generation of complex analog signals. The proposed control method is substantially different: a digital PWM driving waveform is applied using an H-bridge driver. The two outputs of the H-bridge driver are switched between three states - they are either connected to the positive or negative power supply terminal, or disconnected, with a high-impedance output. An H-bridge can also be used for short-circuiting of the actuator, in turn improving the power-efficiency of the IEAP actuator. This control method is particularly beneficial in applying IEAP actuators in soft robotics.