Patent ID: 7390309

Claim:
A method for obtaining an assist torque to be applied to a human joint, in a human assist system for applying an assist torque to the human joint, comprising the steps of: determining a gravity compensation control torque value for a first joint; identifying said gravity compensation control torque as being feasible if the relative angular velocity between first and second segment of said first joint is substantially zero; and identifying a gravity compensation control torque feasibility value when said relative angular velocity between said first and second segments of said first joint is not substantially zero, including the steps of: determining a mechanical energy feasibility value of said gravity compensation control torque, determining a metabolic energy feasibility value of said gravity compensation control torque, the metabolic energy feasibility value based on metabolic efficiencies associated with concentric work and eccentric work, and calculating said gravity compensation control torque feasibility value based upon said mechanical energy feasibility value and said metabolic energy feasibility value.