Control for an electromechanical brake actuator

An aircraft, comprising:

• a wheel;
• and
• a brake system coupled to the wheel, wherein the brake system comprises:
• a pressure plate;
• an end plate;
• a plurality of rotating discs positioned between the pressure plate and the end plate;
• an electromechanical brake actuator controller;
• and
• an electromechanical brake actuator comprising a ball screw configured to extend to exert a force on the pressure plate, the electromechanical brake actuator operatively coupled to the electromechanical brake actuator controller;
• wherein, responsive to receiving a command from the electromechanical brake actuator controller, the electromechanical brake actuator is configured to retract away from the pressure plate to at least one of a first zero-touch point, a second zero-touch point, a third zero-touch point, or a fourth zero-touch point,
• wherein the brake system further comprises a load cell,
• wherein the third zero-touch point is determined by:
• responsive to operating under force control and responsive to an autozero failing to be established for the load cell, determining, by the electromechanical brake actuator controller, a third position of the ball screw in response to the force being applied by the electromechanical brake actuator dropping below a third predetermined force threshold;
• and
• determining, by the electromechanical brake actuator controller, the third zero-touch point by subtracting a third offset from the third position of the ball screw, and
• wherein the fourth zero-touch point is determined by:
• responsive to operating under the force control and responsive to the autozero being established for the load cell, determining, by the electromechanical brake actuator controller, a fourth position of the ball screw in response to the force being applied by the electromechanical brake actuator dropping below a fourth predetermined force threshold;
• and
• determining, by the electromechanical brake actuator controller, the fourth zero-touch point by subtracting a fourth offset from the fourth position of the ball screw.

A method of controlling an electromechanical brake actuator of a brake system comprising:

• receiving, by an electromechanical brake actuator controller, a command from a brake control unit, wherein the command is to retract a ball screw within the electromechanical brake actuator away from a pressure plate, the ball screw configured to extend to exert a force on the pressure plate;
• identifying, by the electromechanical brake actuator controller, at least one of a first zero-touch point, a second zero-touch point, a third zero-touch point, or a fourth zero-touch point for the electromechanical brake actuator;
• and
• commanding, by the electromechanical brake actuator controller, the electromechanical brake actuator to retract the ball screw away from the pressure plate to the at least one of the first zero-touch point, the second zero-touch point, the third zero-touch point, or the fourth zero-touch point,
• wherein the third zero-touch point is determined by the method further comprising:
• responsive to operating under force control and responsive to an autozero failing to be established for a load cell, determining, by the electromechanical brake actuator controller, a third position of the ball screw in response to the force being applied by the electromechanical brake actuator dropping below a third predetermined force threshold;
• and
• determining, by the electromechanical brake actuator controller, the third zero-touch point by subtracting a third offset from the third position of the ball screw, and wherein the fourth zero-touch point is determined by the method further comprising:
• responsive to operating under the force control and responsive to the autozero being established for the load cell, determining, by the electromechanical brake actuator controller, a fourth position of the ball screw in response to the force being applied by the electromechanical brake actuator dropping below a fourth predetermined force threshold;
• and
• determining, by the electromechanical brake actuator controller, the fourth zero-touch point by subtracting a fourth offset from the fourth position of the ball screw.