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DRESS
Distributed and Redundant Electro-mechanical nose wheel Steering System

Tags: Air

Background

An aeroplane is steered on the ground by orienting the nose landing gear wheels. On all commercial aeroplanes today, these wheels are oriented by a hydraulically actuated steering system. On automatic landings, during the automatic braking sequence, the steering system is commanded by the flight control computers in order to keep the aircraft on the runway’s centre line. When reaching the end of the runway, pilots have to regain manual control of the aeroplane as there is no automatic ground guidance on taxiways.

Even the automatic steering during the automatic braking sequence is of limited use since, due to the low safety level of the current steering systems, airworthiness regulations impose a minimum visibility that would allow the pilots to be able to safely regain manual control in case of steering system malfunction and keep the aeroplane on the runway by using manual differential braking.

In lower visibility conditions, all landings, ground manoeuvres and take-offs have to be interrupted.

Continuous efforts are being made by the aeroplane manufacturers and the air traffic management sector to fully automate the approach, landing, ground manoeuvres and take-off in order to increase the air transport system efficiency by being able to operate the airports in true ‘all weather’ conditions.

The weak link today is the current nose landing gear steering system, which must be improved in terms of safety so that it is able to be integrated into the future fully automated ground guidance system, allowing the expected air transport efficiency levels to be reached.

Objectives

The project objective is, therefore, to gradually increase the reliability and safety levels of the aeroplane ground steering system.

Electromechanical redundant actuation technology associated with new modular control system architecture, based on a digital bus network, should allow large improvements in the reliability and safety of the ground steering system to levels compatible with the requirements of a fully automated ground guidance system.

The DRESS architecture will improve safety and fault tolerance while offering an open and modular structure through the digital bus network reconfiguration capabilities, and will provide an easy and safe connection to the future automatic guidance system. The system fault management will be improved by automatic failure localisation.

Another step will be made towards the all-electric aircraft and its associated advantages by eliminating the current hydraulically actuated steering system and its well-known drawbacks.

An overall steering system weight reduction at aircraft level will also be reached, even if the electromechanical actuators could turn out to be slightly heavier than the current hydraulic actuators, since many current hydraulic components associated with the hydraulically actuated system will be deleted.

Single-aisle aircraft nose landing gear
Single-aisle aircraft nose landing gear

Description of work

DRESS will achieve this technology breakthrough, investigating in the fields of both system architecture and electromechanical actuation.

DRESS is composed of the following work packages:

  • The ‘Specifications and assessment criteria’ work package will identify all the requirements, providing a base on which high-level as well as detailed specifications for this new steering system will be established. Assessment criteria will be defined to assess the final validation results in an easier and better way.
  • The ‘Research on optimised system architecture’ work package concerns modular and redundant open control system architecture studies, and also addresses the complex nose landing gear oscillations damping control.
  • The ‘Electromechanical technologies’ work package concerns the electromechanical actuator, a new electric motor architecture, and a safe and segregated power electronics control system
  • The ‘Components manufacture’ and ‘Technology Integration’ work packages will cover the manufacture and then the assembly of various components with first sub-assembly tests.
  • ‘Technology evaluation’: the main components and then the complete validation prototype of the new steering system will be tested against the specifications. An evaluation of this new technology regarding its integration in a production aircraft system will be provided.

Results

A steering system demonstrator will be available at the end of the project which will have been tested on a dedicated rig.

DRESS will develop a cost-effective steering system with an improved level of safety allowing automatic aircraft guidance. Furthermore, DRESS has a global approach: improving the safety critical system architecture with modular and open real-time control loop architecture while introducing jamming-free electromechanical redundant actuators.

DRESS will improve the European aeronautic industry competitiveness, contributing to securing long-term employment in this industry.

It will contribute to education and training via the development and application of new digital and electromechanical techniques, to a large extent based on work carried out by PhD students or young scientists coming from different European countries.

DRESS aims to provide the technology to improve competitiveness and safety, which will contribute towards airport traffic efficiency. This will allow aviation growth in harmony with society needs and efficiency, and thereby enable air travel to become a more efficient transport medium for both people and goods.

By helping to improve airport traffic efficiency, DRESS will contribute towards reducing the air transport system’s energy consumption with a more efficient service without delays.

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