In some embodiments, a method of provided boosted actuation to an aircraft flight control device includes receiving an input from a pilot input device via a mechanical input member, providing mechanical energy to a driving member of a controlled-slippage actuator, and varying the strength of a magnetic field applied to a magnetorheological (MR) fluid disposed between the driving member and a driven member of the controlled-slippage actuator based on the relative positions of the mechanical input member and a mechanical output member that is in mechanical communication with the driven member and the aircraft flight control device.