Coordinating control of a two degrees of freedom universal joint structure driven by three servos

A structure of 3 servos driving a 2 d.o.f, universal joint through wire is introduced. A lower level coordinate transformation set is developed and includes positional, velocity and force transformations. Inverse transformations are included. Special attention is given to the inverse force transformation which is obtained using linear optimization. As an example a joint control system including servos under force control is outlined.