Impedance Control

What is The Joint Impedance? The Automatic Capability of the System to Resist an Applied Load before Voluntary Intervention Takes Place (Winters et al. 1988) Stiffness is defined as the ratio of change in force or torque to change in length or angle Viscosity is defined as the ratio of change in force or torque to change in velocity or angular velocity

Stiffness Control F = k ( X – X0) :رابطه يك فنر (عضله) K = σ (α )

How Joint Impedance May Be Control? 1- Nonlinear Muscle and Joint Prpperties. 2- Co-contractions 3- Reflexes and co-activation

Stiffness Control Hassan, 1986

Stiffness Control

Roughly Speaking, The Axis of Maximum stiffness is a Line that Connect The Hand to a Point between Shoulder and Half Way Through the Elbow Mussa-Ivaldi et al. 1985

Adapted From Gomi & Osu 1998

Co-Contraction Increase The Mechanical Stability of The Joint But at Greater Metabolic Cost Burdet et al. 2001

Experimental Setup Arm Configuration During The Experiment Interactive Motion Technologies, Cambridge MA

EPH Generalization