Improved actuator and retraction mechanisms for force feedback exoskeletons are described. An actuator assembly for a force-feedback exoskeleton comprising: a rotating body coupled to a tendon and to a spring, said spring configured to produce a torque on the rotating body; and a second body having a surface configured to apply a variable force to a surface of the rotating body by means of a membrane enclosing a volume fluidically coupled to at least one control valve and to a pressurized fluid source, wherein the volume enclosed by the membrane comprises: a first pressure state in which the rotating body contacts the second body; and a second pressure state in which the rotating body does not contact the second body.