A powered device (450) for augmenting a joint function of a human during a gait cycle, the device comprising a powered actuator (454) for supplying at least one of an augmentation torque and an impedance to a joint, and a controller configured to modulate the augmentation torque, the impedance, and a joint equilibrium according to a phase of the gait cycle to provide at least a biomimetic response, characterized in that the controller is further configured to modulate, within the gait cycle, the augmentation torque, the impedance, and the joint equilibrium according to a speed of ambulation or terrain.
