Development of a Magneto-Rheological Fluid-Based Trim Actuator with Active Tactile Cueing Capabilities

A magneto-rheological (MR) fluid-based trim actuator is being developed for rotorcraft applications. The device can provide active tactile cues to the pilot in the form of infinitely variable force gradients, stick shaking, and soft stops. Tactile cueing has proved to be an effective method of increasing situational awareness, especially during emergency situations and can reduce pilot workload for increased operational safety. The MR actuator uses magneto-rheological fluid to permit variable slippage between rotating clutch surfaces. With an MR fluid, the torque transfer between the clutch surfaces is dependent upon a user controlled magnetic field that is used to modulate output forces applied to control linkages. This paper discusses the design of the MR trim actuator and the control logic used to implement active tactile cueing. The latest experimental results on a single axis test bench are presented and discussed. The prototype work shows that MR technology can provide broad tactile cueing functionality with size and weight similar to conventional trim actuators found on light aircraft that lack tactile cueing functions.