Towards efficient elastic actuation in bio-inspired robotics using dielectric elastomer artificial muscles

In nature, animals reduce their cost of transport by utilising elastic energy recovery. Emerging soft robotic technologies such as dielectric elastomer actuators (DEAs) offer an advantage in achieving biomimetic energy efficient locomotion thanks to their high actuation strain and inherent elasticity. In this work, we conduct a comprehensive study on the feasibility of using antagonistic DEA artificial muscles for bio-inspired robotics. We adopt a double cone DEA configuration and develop a mathematical model to characterise its dynamic electromechanical response. It is demonstrated that this DEA design can be optimised in terms of the maximum work output by adjusting the strut height design parameter. Using this optimised design, we analyse the power/stroke output and the electromechanical efficiency of the DEA and show how these actuation characteristics can be maximised for different payload conditions, excitation frequencies and actuation waveforms. The elastic energy recovery from the DEA is then demonstrated by reducing the duty ratio of the actuation signal and thus allowing the stored elastic energy in the DEA membranes to contribute to the work output. A bio-inspired three-segment leg prototype driven by the same actuator is presented to demonstrate that the same energy recovery principle is feasible for bio-inspired robotics.