A thrust controller for the dynamic test bed of the flight management system

摘要

The following study presents the Thrust Controller (TC) design and validation for a large civil aircraft, the Boeing 747. The TC works with the Automatic Flight Control System (AFCS) and the Flight Management System (FMS) to provide automatic, full-flight-regime energy management with minimum pilot inputs. The controller is to be coupled to the pitch channel of the AFCS to eliminate any altitude variation during thurst manoeuvres and will be available throughout the entire flight envelope. The proposed system is integrated within the Dynamic Test Bed (DTB) developed by CMC Electronics and its partners. In fact, in an attempt to minimize costs and reduce "in air" testing, CMC wishes to fully develop the concept of a real-time DTB, a simplified aircraft simulator, and to expand it into audcomprehensive FMS design and test tool, capable of certified service. The goal of the present study is the design, simulation, integration and qualification of the TC using the DTB as the integration platform. After a brief review of the command law synthesis methods for aircraft thurst control two concepts were studied. First the thurst controller was developed using a classic single inputsingle output controller based on the Proportional-Integral-Derivative structure and was validated over the full flight envelope. The controller is coupled to the pitch channel using an altitude variation dependant gain on the speed channel to eliminate altitude variation during speed control manoeuvres using thurst increase and decrease. The second design architecture proposes a modem state-feedback controller that fully couples pitch and speed channels. Feedback gains were chosen for every linearized point using the Eigenvector assignment method for system robustness. A controller was thus designed for every linearized point and the TC system switches between controllers according to flight conditions. Many improvements were then added to both controllers' architectures to add speed and thurst limitations and placards protections prior to nonlinear integration. The integration of the modem controller could not be validated within the nonlinear DTB framework in the scope of the current project due to autopilot and platform limitations. On the other hand, the classical controller proposed is integrated and tested within the nonlinear conditions of the DTB. To qualify the TC as a design and test tool and integrate it in the DTB we sought to ensure its smooth functioning and to reach the performance awaited while respecting the various limits and placards. A set of qualification tests was written and mn for that purpose. The results were judged satisfactory as the aircraft settles within the required limitations while improvements can be made and recommendations are presented.