Envelope protection systems for piloted and unmanned rotorcraft

Performance and agility of rotorcraft can be improved using envelope protection systems (or carefree maneuvering systems), which allow the aircraft to use the full flight envelope without risk of exceeding structural or controllability limits. Implementation of such a system can be divided into two necessary parts: "Limit Prediction" which detects the impending violation of the limit parameter, and "Limit Avoidance" where a preventive action is taken in the form of pilot cueing or autonomous limiting. Depending upon the underlying flight control system, implementation of the envelope limiting system was categorized into two different structures: "Inceptor Constraint Architecture" and "Command Limiting Architecture".; The Inceptor Constraint Architecture is applicable to existing rotorcraft with conventional flight control system where control input proportionally affects control surfaces. The relationship between control input and limit parameter is complex which requires advanced algorithms for predicting impending limit violations. This research focuses on limits that exceed in transient response. A new algorithm was developed for predicting transient response using non-linear functions of measured aircraft states. The functions were generated off-line using simulation data from a non-real-time simulation, model to demonstrate the procedure for extracting them from flight test data.; Modern rotorcraft flight control systems are designed to accurately track certain aircraft states like roll and pitch attitudes which are either specified as command inputs in unmanned rotorcraft or mapped to control stick in piloted aircrafts. In the Command Limiting Architecture applicable to these systems, performance constraints were generated on the command input corresponding to the envelope limit. To simulate this flight control system, an adaptive model inversion controller was applied to a non-linear, blade element simulation model of a helicopter. The controller generated fully-coupled lateral, longitudinal, vertical and yaw axis control inputs using a single design point linear model. (Abstract shortened by UMI.)...