A system comprises one or more wearable devices including a first bodyinterface adapted to be secured to a first bodilypart. A second body interface is adapted to be secured to a second bodily partseparated from the first bodily part by a physiologicaljoint. One or more joints provide one or more degrees of freedom between thefirst body interface and the second body interface. Amagnetorheological (MR) fluid actuator unit comprises one or more powersources. An MR fluid clutch apparatus receiving torque fromthe at least one power source, the at least one MR fluid clutch apparatusoperable to generate a variable amount of torque transmissionwhen subjected to a magnetic field. A transmission couples the MR fluidactuator unit to the wearable device for converting torquefrom the MR fluid actuator unit to relative movement of the body interfaceswith respect to one another.
