A device for guiding and detecting motions of a target joint , the device comprising: - a motion generator having a plurality of actuators (5-7), a driver in communication with the plurality of actuators (5-7), a moving component and a network of joints and linkages interconnected with the plurality of actuators (5-7), a coordinated action of the plurality of actuators (5-7) and network of joints and linkages of the motion generator generating motion at the moving component with a first center of rotation that does not coincide with a center of rotation of the target joint ; - a motion transfer and target interfacing unit connected to the moving component of the motion generator and the target joint , the motion transfer and target interfacing unit comprising at least one rotary joint, at least one linear-motion joint comprising a sliding component and a track component , a mounting means coupling the motion transfer and interfacing unit to the target joint and a network of linkages and joints interconnected together to join the at least one rotary joint and the at least one linear-motion joint, the sliding component interfacing the track component to slide along the track component , the motion transfer and target interfacing unit configured to transfer the motion generated by the motion generator at the moving component to provide a 3-DOF rotational motion at the mounting means with a center of rotation that coincide with a center of rotation of the target joint , while the center of rotation of the moving component of the motion generator does not overlap with the center of rotation of the target joint ; and - a controller in communication with the motion generator and the motion transfer and target interfacing unit , the controller comprising an input unit, an output unit and a processing unit, the controller sending output signal to the motion generator to actuate the driver of the at least one actuator (5-7). - a motion generator having a plurality of actuators (5-7), a driver in communication with the plurality of actuators (5-7), a moving component and a network of joints and linkages interconnected with the plurality of actuators (5-7), a coordinated action of the plurality of actuators (5-7) and network of joints and linkages of the motion generator generating motion at the moving component with a first center of rotation that does not coincide with a center of rotation of the target joint ; - a motion transfer and target interfacing unit connected to the moving component of the motion generator and the target joint , the motion transfer and target interfacing unit comprising at least one rotary joint, at least one linear-motion joint comprising a sliding component and a track component , a mounting means coupling the motion transfer and interfacing unit to the target joint and a network of linkages and joints interconnected together to join the at least one rotary joint and the at least one linear-motion joint, the sliding component interfacing the track component to slide along the track component , the motion transfer and target interfacing unit configured to transfer the motion generated by the motion generator at the moving component to provide a 3-DOF rotational motion at the mounting means with a center of rotation that coincide with a center of rotation of the target joint , while the center of rotation of the moving component of the motion generator does not overlap with the center of rotation of the target joint ; and - a controller in communication with the motion generator and the motion transfer and target interfacing unit , the controller comprising an input unit, an output unit and a processing unit, the controller sending output signal to the motion generator to actuate the driver of the at least one actuator (5-7). <EOS>