A method includes determining, on a processor, a current movement phase for a compound joint function based on sensor data. The method further includes determining, on the processor, a respective robot state parameter trace for each movement phase in a normal and impaired subject. The method further includes determining, on the processor, a deficit parameter for each movement phase. The method further includes determining, on the processor, an adaptive magnitude for the robot applied torque based on the deficit parameter of the current movement phase. The method further includes applying, to the robot joint, the adaptive magnitude for the robot applied torque for the current movement phase, based on an adaptive timing for the current movement phase. An apparatus is also described for providing deficit-adjusted adaptive assistance during movement phases of the impaired joint.