Energy approach to flight control system design

B.V. Pavlov, A.M. Shevchenko, G.N. Nachinkina

V.A. Trapeznikov Institute of Control Problems of RAS

65, Profsoyuznaya, Moscow, 117997, Russia

e-mail: anshev@ipu.rssi.ru

 

Methods based on total energy control (TEC) proved to be very useful for controlling the vehicle motions. The TEC principle was first investigated and applied to aircraft control. The total energy is used in many problems such as the classical problems of flight-path optimization by the criteria for maximal flying distance, rate of ascent, direct maintenance, minimal intercept time, etc.

The present paper aims at (i) elucidating the relations between the energy state of the aircraft, mode of operation of its power plant, and environmental energy characteristics and (ii) using this dependence to design the structure of the longitudinal channel of the automatic control system and support the pilot's actions in the manual mode. By introducing the energy estimate of the atmosphere, we succeeded in obtaining the energy balance equation in the "vehicle-power plant-environment" system. This equation not only shows a direct way of designing efficient automatic flight control systems, but also enables one to evaluate and communicate to the pilot the danger level of wind disturbances and generate the director index for manual control of the power plant.

Therefore, consideration of aircraft flight from the energy standpoint provides a common procedural ground for joint solution of many problems of flight control. As was corroborated by numerous experimental studies, the results of the present paper are fairly universal, which allows us to claim that we have developed the energy approach to flight contro.

Consideration of aircraft flight in the terrestrial gravitational field from the point of view of variations of the motion energy proved a success for the integrated solution of many problems of flight automation. The present study has given a procedural justi-fication of the energy approach - the energy balance equation. The energy approach enabled one to establish and realize some useful results. The structure of the modified energy control system for an aircraft with essentially nonlinear aerodynamics has been developed. Indication of the danger level of the acting disturbances aids the pilot in deciding whether to continue the current stage of flight (for example, landing) or abort it and to change the trajectory. The introduction of the director mark for engine control is a qualitatively new proposal in the domain of flight automation. The quality of control processes under extremal conditions is substan-tially higher than in the case of the standard system, and piloting resembles that of an expert pilot.