A stiffness control schema for perturbed and unperturbed joint movement

A model for controlling the position of a joint is presented. The model is based on the stiffness control strategy which is supposed to play an important role in the control of both human posture and human movement. To compensate for the effect of external disturbances, a feedforward mechanism is used in the model. Two cases are considered: unperturbed, inertial-visco-stiffness loaded movements, and perturbed movements by additive measurable disturbance. The optimal trajectory for both cases is computed by using the subject effort as a criterion function, as was proposed by Z. Hasan (1986).