Torque control capability is provided to a position controlled robot by
calculating joint position inputs from transformation of the desired
joint torques. This is based on calculating the transfer function 1/E(s),
which relates the desired joint torque to joint position. Here E(s) is a
servo transfer function D(s) or an effective servo transfer function
D*(s). The use of an effective servo transfer function D*s) is helpful in
cases where joint nonlinearities are significant. The effective servo
transfer function D*(s) is defined with respect to an ideal joint
transfer function G*(s)=1/(I.sub.effs.sup.2+b.sub.effs), where I.sub.eff
is an effective moment of inertia and b.sub.eff is an effective damping
coefficient.