Power/energy metrics for controller evaluation of actuators similar to biological systems

An evaluation of controller design is performed on an actuator, which resembles a biological system (pneumatic muscle actuator). The procedures studied herein do not require any presumptions of linearity or stationarity. A comparison across various controllers was obtained by considering a pneumatic muscle system being used in a force control sense over a full cycle of operation. Such an actuator has many advantages (extremely high power/weight, power/volume and power/energy ratios). A number of power and energy related measures were assessed including: (1) a workloop metric to specify the external work output of the actuator produced on the environment, (2) a power ellipsoid method to examine efficiency over one cycle of operation, and (3) other key power and energy related criteria, e.g. when peak power varies as a function of the velocity produced.