Synthesis and dynamics of statically balanced direct-drive manipulators with decoupled inertia tensors

This paper addresses conceptual design of direct-drive manipulators which have good promise for high speed, high precision manipulation. In the design methodology presented, the procedure begins by considering the kinematic aspects and ends by configuring manipulator structures with promising kinematic and dynamic characteristics. Based on the conceptual design considerations, two novel manipulator designs, a 2 and 3 DOF manipulator, are proposed and analyzed. Conditions for static balancing and decoupled invariant dynamics for the 2 DOF manipulator are derived. Design guidelines are also derived for static balance of the 3 DOF manipulator and for achieving decoupled and nearly invariant inertia tensor (two constant diagonal elements out of three). The two designs have the advantage over the currently known direct-drive manipulators of achieving both of the two desirable mechanical features, namely: static balancing and decoupled inertia tensor.