An Inverse Dynamic Model of a Spherical Electrohydraulic Actuator for Use in a Dexterous Mechanical Hand

The purpose of this paper is the development of an inverse dynamic model of a two degree of freedom electrohydraulic actuator. The actuator is to be incorporated at the base of each of three fingers of a nine degree of freedom mechanical hand, currently under development. Motion in the proposed actuator is facilitated about intersecting pitch and yaw axes, thus creating spherical actuation. The dynamic model incorporates frictional and hydraulic losses, commonly overlooked sources of energy dissipation. The model is to be used in the control scheme of the mechanical hand and in the optimal synthesis procedure of the actuator. The latter application, briefly described here, takes into account specified motion and torque requirements, pressure, peak input force and size constraints. Particular attention is paid to traditional performance indices, such as mechanical advantage.