Size vs. power-to-weight ratio in integrated actuation

Investigates whether there exists some universal trend such that an actuator utilizing the same kind of energy source but having a small size will have an intrinsic advantage in terms of power-to-weight ratio (PWR). The results indicate that this trend does not exist in general. In fact it is found that the maximum PWR of most electric motors is independent of motor size even though their force-to-weight ratio (FWR) may vary, except that the PWR of striated muscles of vertebrates increases with muscle size. Therefore, the advantage of integrated actuation must come from other aspects such as flexibility in controlling shape, velocity and force, robustness, etc.