Creation of the requirements for the dynamics and main parameters of the control loops of an advanced agile aircraft flight control actuator
Аuthors1*, 1, 2**, 3***
1. Pavlovsky Mashinostroitelny Zavod «Voskhod», PMZ «Voskhod», 78a, Kommunisticheskaya str., Pavlovo, Nizhny Novgorod Region, 606100, Russia
2. Central Aerohydrodynamic Institute named after N.E. Zhukovsky, TsAGI, 1, Zhukovsky str., Zhukovsky, Moscow Region, 140180, Russia
3. Scientific-Research Institute (Girikond), 10, Kurchatova Str., Sankt-Peterburg, 194223, Russia
The paper reviews the key problems, which arise during the development of a flight control actuator for an advanced agile aircraft. These problems are related to the creation of the requirements for the dynamics and main parameters of the control actuator, which are justified from the engineering point of view. The example of a flight control actuator design illustrates the main methodological approaches to the selection of the values of its control loop main parameters for the advanced agile aircraft with aerodynamically unstable configuration. The values are selected in such a way as to provide the required dynamics of the «aircraft — flight control system — flight control actuator» closed-loop system.
The paper suggests a methodological approach to the creation of justified requirements, which are represented as regions of acceptable values of the amplitude-phase-frequency response characteristic of a horizontal tail control actuator depending on the input signal amplitude. These requirements ensure the complete elimination of the self-oscillating modes in the «aircraft — flight control system — flight control actuator» closed-loop system. In addition the paper proposes a method of determining the basic values of the actuator control loop parameters, which ensure the required actuator dynamics in the whole region of input signal computation. It is shown that the required actuator dynamics can only be attained via the implementation of a comprehensive approach. Such approach should include the selection of a rational functional diagram of the actuator with the use of concept of direct control of flow control valves. It should also encompass the design and manufacturing methods, which would provide the required linearity of the response rate performance of the servo actuator and hydraulic motor of the flight control actuator. Another important part of the method would be the use of digital controllers, which ensure the required stability of the actuator technical performance during the exposure to the destabilizing factors and in the presence of functional failures.
Keywords:agile aircraft, aerodynamically unstable configuration, fly-by-wire control system (FBW), amplitude-phase-frequency response characteristic, electro-hydraulic flight control actuator, servo actuator
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