Comparative study of robotic artificial actuators and biological muscle

Biological muscles exhibit a high level of integration, in which actuators, sensors and transmission elements can be included in one component. Artificial muscles or actuators refer to intelligent stimuli-responsive materials that could reversibly deform with the trigger of various external stimuli. These materials, which have attracted tremendous attention, produce natural muscle-like actuation performance and show promising applications in robotics. After an introduction of various actuator technologies that contribute to robotic applications, a comparative analysis of the main actuation parameter is provided. The comprehensive comparisons of each kind of artificial muscle are summarised, and the promising properties that are required in robotics are presented, which highlight the development of their actuation performances and the challenges that limit their further employments. Future developmental prospects and perspectives of artificial actuators are discussed.