Development and evaluation of a unified control architecture for a compound rotorcraft in maneuvering flight

A unified control system featuring an energy management system was developed and evaluated in simulation for a compound rotorcraft. Non-linear dynamic inversion (NLDI) is the framework of the unified controller, which incorporates primary and redundant controls. The inner loop of the NLDI controller regulates bank angle, pitch attitude, and yaw rate, while the outer loop command structure is varied (3 modes). One version uses an outer loop that commands velocities in the longitudinal and vertical axes (velocity mode). Another version commands longitudinal acceleration and vertical speed (acceleration mode). The third mode commands longitudinal acceleration and transitions from velocity to acceleration command in the vertical axis (aerobatic mode). The unified outer loop control effectors (collective pitch, pitch attitude, and propeller pitch) vary depending on flight regime. The collective pitch and pitch attitude are used at low speeds while pitch attitude and propeller pitch are used at high speeds; during the transition to/from the high speed flight regime a weighted pseudo inverse is used to phase either the collective or propeller pitch in/out of a redundant control role. The controllers were evaluated in Penn State's Rotorcraft Simulator retaining the cyclic stick and pedals as inceptors. A throttle inceptor was used in place of the pilot's traditional left hand inceptor (collective stick). Basic maneuvers were performed throughout the flight envelope to assess the unified controllers' performance in both tracking commands and managing energy (total power required).