The effect of load conditions on the design and performance of actuators

This paper demonstrates the effect of dynamic load conditions on the design and performance of actuators. Actuators have both active and passive properties that determine their overall performance. The interaction between the active and passive components of an actuator, and hence the performance, will depend on both the objective (i.e., the actuator used in a control system or as a source) and the dynamics of the structure to which the actuator is attached. It is shown that it is mainly the active properties of an actuator which are affected by the load conditions of the structure. Changes in the active properties due to varying load conditions are demonstrated for various actuator types. By altering the passive properties of an actuator (i.e., mass and stiffness) it is possible to enhance the performance of the actuator used in a particular application. It is shown that the optimal actuator design depends on both the dynamics of the structure to which the actuator is attached and the performance objective. It will be demonstrated that actively changing the passive properties of an actuator allows significant enhancement of performance.