Tilt rotor control

A tilt rotor system for an aircraft, comprising:

• a rotor pylon;
• an actuator connected to the rotor pylon to move the rotor pylon between a first position and a second position, wherein the first position is a vertical position and the second position is a horizontal position;
• a drive mechanism to drive the actuator between the first and second positions, in response to an input command;
• and
• a stop mechanism to secure the rotor pylon in the second position;
• the drive mechanism comprising:
• a variable displacement motor having sensors for measuring
• a swash angle of the motor,
• speed of the motor, and
• an actual tilt position of the rotor pylon, and
• means for providing feedback control to the variable displacement motor to control the drive power of the motor based on the monitored swash angle, motor speed and actual tilt position of the rotor pylon, and
• wherein the means for providing feedback control includes an algorithm configured to monitor change in swash angle as the motor speed reduces and the actual tilt position of the rotor pylon approaches the second position and, based on the change in the swash angle, the actual tilt position of the rotor pylon, and a reduced power requirement as the system reaches the second position, to limit change in swash angle to be within a predetermined range as a percentage of the operating load.