Fly-by-wire control systems and servo actuators design and development

Аuthors

Ermakov S. A.^1*, Karev V. I.^1**, Konstantinov S. V.², Obolensky Y. G.^***, Selivanov A. M.^1****, Sukhorukov R. V.^3*****

1. Moscow Aviation Institute (National Research University), 4, Volokolamskoe shosse, Moscow, А-80, GSP-3, 125993, Russia
2. PJSC UAC Sukhoi Design Bureau, 23A, Polikarpova str., Moscow, 125284, Russia
3. Kompani «Kronshtadt», 54-4, Malyi ave., Saint-Petersburg, 199178, Russia

*e-mail: ermakov1029@yandex.ru
**e-mail: karev_39@mail.ru
***e-mail: y.obolensky@rsk-mig.ru
****e-mail: nselivanova2000@mail.ru
*****e-mail: roman.sukhorukov@irkut.com

Abstract

This article considers the design principles of fly-by-wire systems of modern military aircraft and passenger airplane, principle design schemes of servoactuators with higher reliability, as well as application of heterogeneous redundancy in actuators systems of the critical control surfaces. It is shown that development of the modern aircraft control system dictates transition to the integrated digital complex control systems that ensure manual and automatic flight control with specified stability and controllability characteristics.
The modern combat aircraft have unstable aerodynamic configuration, and the new passenger aircraft have low-stable configuration. That allows considerable enhance of the aircraft performance, however requires artificial improvement of the aircraft stability and development of new, more reliable automatic control systems. As an example, we consider a combat aircraft control system that performs functions of all piloting systems at the same time. The system design features a single control complex that combines both the aerodynamic surface control actuators and the control actuators of the exhaust nozzles of cruise engines with variable thrust vector. Also the article considers a redundant design of the aircraft power system, in which a failure of an engine, hydraulic system or power generation channel does not result in the control system failure. The combat aircraft design features electro-hydraulic servo actuators with the direct control valve.
Airlines are interested in increase of power efficiency of servo actuators and decrease of aircraft maintenance costs, so they are keen to minimize the number of hydraulic systems. That leads to development of new servo actuator types — electrohydrostatic actuators. Such actuators allow to minimize the number of onboard centralized hydraulic systems on the aircraft. The actuators have following advantages: lower energy consumption, a higher efficiency factor, a possibility to boost the maximum pressure. The work provides a scheme of the new type servo actuator suggested by MAI specialists, in order to enhance dynamics in the low signal area. This is the servo actuator with combined control of the output link speed.
On the aircraft that feature the power electric system along with one or two centralized hydraulic systems, it is expedient to use hybrid servo actuators with heterogeneous redundancy, where one channel is powered by the centralized hydraulic system and the other channel is powered by the electrical system. Such architecture of fly-by-wire control system allows additional enhance of failure safety of the aircraft servoactuators. This article considers the ways how to ensure flight control of a passenger aircraft even in case of failure of all regular electric power systems and/or electronic control units along with electric sensor, due to lightning strike, static electricity exposure, high radio radiation, radiation or other similar disturbance exposure.

Keywords:

fly-by-wire control flight systems, jet, backup drive system, electrohydraulic servoactuator

References

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