Patent ID: 8033509

Claim:
An aircraft flight control surface actuation system, comprising: an electromechanical actuator assembly adapted to be selectively supplied with electrical current and, upon receipt of the electrical current, to supply a force to a flight control surface; a hydraulic actuator assembly adapted to selectively receive a supply of hydraulic fluid and, upon receipt of the hydraulic fluid, to supply a force to the flight control surface; a hydraulic actuator control adapted to receive a position command signal representative of a commanded flight control surface position and operable, in response thereto, to control the supply of hydraulic fluid to the hydraulic actuator assembly; and an electromechanical actuator control operable to control the electrical current supplied to, and thus the force supplied by, the electromechanical actuator assembly, the electromechanical actuator control including: a position error determination function, the position error determination function adapted to receive (i) the position command signal and (ii) a position sensor signal representative of at least electromechanical actuator assembly position and operable, in response to the position command signal and the position sensor signal, to (i) determine a position error representative of a difference between the commanded flight control surface position and the electromechanical actuator assembly position and (ii) supply a position error signal representative of the position error, and a current limit determination function, the current limit determination function coupled to receive the position error signal and operable, in response thereto, to determine a current limit value, the current limit value representative of a maximum magnitude of the electrical current that the electromechanical actuator control supplies to the electromechanical actuator assembly, wherein the current limit value is (i) a non-zero predetermined current magnitude when a magnitude of the position error is less than or equal to a first predetermined error magnitude, and (ii) greater than the non-zero predetermined current magnitude when the magnitude of the position error is greater than the first predetermined error magnitude.