Browse Topic: Fly-by-wire control systems
Over the past few decades, aircraft automation has progressively increased. Advances in digital computing during the 1980s eliminated the need for onboard flight engineers. Avionics systems, exemplified by FADEC for engine control and Fly-By-Wire, handle lower-level functions, reducing human error. This shift allows pilots to focus on higher-level tasks like navigation and decision-making, enhancing overall safety. Full automation and autonomous flight operations are a logical continuation of this trend. Thanks to aerospace pioneers, most functions for full autonomy are achievable with legacy technologies. Machine learning (ML), especially neural networks (NNs), will enable what Daedalean terms Situational Intelligence: the ability to understand and make sense of the current environment and situation but also anticipate and react to a future situation, including a future problem. By automating tasks traditionally limited to human pilots - like detecting airborne traffic and identifying
This document provides a description of a process for development of fly-by-wire actuation systems. Included are (1) the development of requirements for the servo-actuator hardware and the electronics hardware and software, (2) actuator and servo-electronics interface definitions and, (3) the required communications and interactions between the servo-actuator and the servo-electronics designers.
Flight in icing for transport category aircraft certification presents a particularly challenging set of considerations to establish adequate safety commensurate with the associated risk while balancing design complexity and efficiency. A review highlighting important aspects of the regulatory evolution and guiding principles for flight in icing certification is presented, including the current standards and recent rulemaking activity. While historical icing certification relied on a simple yet subjective requirement to demonstrate that an aircraft is capable of operating safely within the prescribed icing envelopes, the certification requirements associated with demonstrating an adequate level of safety have progressively evolved into more explicit quantitative performance and qualitative handling qualities standards now scattered throughout the Federal Aviation Administration (FAA) Title 14 Code of Federal Regulations (CFRs) Part 25 Subpart B Flight standards which are largely
The development and qualification of distributed and highly safety-critical avionics systems implicate high efforts and risks. The resulting costs usually limit implementations like fly-by-wire systems to the military or commercial airliner domains. The aim of previous and ongoing research at the Institute of Aircraft Systems at University of Stuttgart is the reduction of these costs and therefore open up their benefits, inter alia, to general aviation, remotely piloted or unmanned aircraft. An approach for an efficient development is the application of a platform based development which supports the reuse of software and hardware components. The Flexible Platform adopts this approach. It is accompanied by a tool suite which automates the design and parameter instantiation, documentation generation and the generation of verification artifacts for a platform instance. This paper presents the approach for the requirement document generation compliant to ARP4754A and DO-178C. It is based
This SAE Aerospace Recommended Practice (ARP) provides general requirements for a generic “passive” side stick that could be used for fly by wire transport and business aircraft. It addresses the following: The functions to be implemented The geometric and mechanical characteristics The mechanical and electrical interfaces The safety and certification requirements
This SAE Aerospace Information Report (AIR) provides design information of various contemporary aircraft fly-by-wire (FBW) flight control actuation systems that may be useful in the design of future systems for similar applications. It is primarily applicable to manned aircraft. It presents the basic characteristics, hardware descriptions, redundancy concepts, functional schematics, and discussions of the servo controls, failure monitoring, and fault tolerance. All existing FBW actuation systems are not described herein; however, those most representing the latest designs are included. While this AIR is intended as a reference source of information for aircraft actuation system designs, the exclusion or omission of any other appropriate actuation system or subsystem should not limit consideration of their use on future aircraft.
This SAE Aerospace Information Report (AIR) supplies information on the flight control systems incorporated on various current and historic fixed wing, rotary wing, and tilt rotor aircraft. A brief description of the aircraft is followed by a description of the flight control system, some specific components, drawings of the internal arrangement, block diagrams, and schematics. System operation redundancy management is also presented.
This SAE Aerospace Information Report (AIR) provides a description of the interfaces and their requirements for generic and specific hydraulic actuation systems used in the flight control systems of manned aircraft. Included are the basic control system characteristics and functional requirements, and the essential interfaces (structural, mechanical, hydraulic power, control input, status monitoring, and environment). Major design issues, requirements, and other considerations are presented and discussed.
This SAE Aerospace Information Report (AIR) has been prepared to provide information regarding options for optical control of fluid power actuation devices. It is not intended to establish standards for optical fluid power control, but rather is intended to provide a baseline or foundation from which standards can be developed. It presents and discusses approaches for command and communication with the actuation device via electro-optic means. The development of standards will require industry wide participation and cooperation to ensure interface commonality, reliability, and early reduction to practice. To facilitate such participation, this document provides potential users of the technology a balanced consensus on its present state of development, the prospects for demonstration of production readiness, and a discussion of problem areas within this technology. The intent is to inform the user/designer of the options available for interfacing photonics (optics) to hydraulic power
Advanced commercial aircraft increasingly use more composite or hybrid (metal and composite) materials in structural elements and, despite technological challenges to be overcome, composites remain the future of the aviation industry. Composite and hybrid aircraft today are equipped with digital systems such as fly by wire for reliable operations no matter what the flying environment is. These systems are however very sensitive to electromagnetic energy. During flight, aircraft can face High Intensity Radiated Fields (HIRF), static electricity, or lightning. The coupling of any of these threats with airframe structure induces electromagnetic energy that can impair the operation of avionics and navigation systems. This paper focuses on systems susceptibility in composite aircraft and concludes that the same electromagnetic rules dedicated to all metal aircraft for systems and wiring integration cannot be applied directly as such for composite aircraft.
A multi-axis serially redundant, single channel, multi-path FBW (FBW) control system comprising: serially redundant flight control computers in a single channel where only one “primary” flight control computer is active and controlling at any given time; a matrix of parallel flight control surface controllers including stabilizer motor control units (SMCU) and actuator electronics control modules (AECM) define multiple control paths within the single channel, each implemented with dissimilar hardware and which each control the movement of a distributed set of flight control surfaces on the aircraft in response to flight control surface commands from the primary flight control computer, and a set of (pilot and co-pilot) controls and aircraft surface/reference/navigation sensors and systems which provide input to a primary flight control computer and are used to generate the flight control surface commands in accordance with the control law algorithms implemented in the flight control
On September 30, 2011, certification authorities released Advisory Circular 20-174[1], Development of Civil Aircraft and Systems, which recognizes the Society of Automotive Engineers (SAE) Aerospace Recommended Practice (ARP) 4754A and the European equivalent ED-79A [2], in order to address “the concern of possible development errors due to the ever increasing complexity of modern aircraft and systems.” ARP4754A/ED-79A describes a process of development assurance which helps reduce the risk of design errors in the development of aircraft systems. This process is necessary for complex systems not easily comprehended by deterministic analyses or tests. This ARP was developed “in the context of Title 14 of the Code of Federal Regulations (14 CFR) part 25,” a category which includes complex systems such as full fly-by-wire flight controls. However, this paper shows that such systems are the exception to most, recent civil airplane designs. Of new airplanes designed in the last 10 years
Aircraft utilize electrical power for many functions ranging from simple devices such as resistive heaters to highly advanced and complex systems responsible for communications, situational awareness, electronic warfare and fly-by-wire flight controls. The operational states of these electronic systems affect safety, mission success and the overall economic expense of operation and maintenance. These electronic systems rely on electrical power within established limits of power quality. In recent years, electrical power quality is becoming excessively degraded due to increased usage of nonlinear and dynamic loads coupled to aircraft power systems that were neither designed nor tested for these loads. Legacy power generation systems were designed for electrical loads with resistive and inductive properties, which previously represented the majority of actual aircraft electrical loads. As more complex and advanced electronic systems were invented, mostly due to developments in
This SAE Aerospace Recommended Practice (ARP) provides general requirements for a generic “passive” side stick that could be used for fly by wire transport and business aircraft. It addresses the following: The functions to be implemented The geometric and mechanical characteristics The mechanical and electrical interfaces The safety and certification requirements
This guide provides detailed information, guidance, and methods related to the Federal Aviation Administration (FAA) Advisory Circular (AC) 20-158 and European Aviation Safety Agency (EASA) draft Advisory Material Joint (AMJ), both titled "The Certification of Aircraft Electrical and Electronic Systems for Operation in the High-Intensity Radiated Fields (HIRF) Environment". The AC provides acceptable means, but not the only means, of compliance with Title 14, Code of Federal Regulations (14 CFR) 23.1308, 25.1317, 27.1317, and 29.1317, High-Intensity Radiated Fields (HIRF) protection for Aircraft Electrical and Electronic Systems, and applicable FAA HIRF Special Conditions to prevent hazards to aircraft electrical and electronic systems due to HIRF produced by external transmitters. It is also intended for this guide to provide the same information, guidance, and methods to the European Aviation Safety Agency (EASA) interim HIRF policies certification requirements. This guide is neither
This SAE Aerospace Information Report (AIR) provides a description of the interfaces and their requirements for generic and specific hydraulic actuation systems used in the flight control systems of manned aircraft. Included are the basic control system characteristics and functional requirements, and the essential interfaces (structural, mechanical, hydraulic power, control input, status monitoring, and environment). Major design issues, requirements, and other considerations are presented and discussed.
This AIR provides descriptions of aircraft actuation system failure-detection methods. The methods are those used for ground and in-flight detection of failures in electrohydraulic actuation systems for primary flight control. The AIR concentrates on full Fly-By-Wire (FBW) flight control actuation though it includes one augmented-control system. The background to the subject is discussed in terms of the impact that factors such as the system architecture have on the detection methods chosen for the flight control system. The types of failure covered by each monitoring technique are listed and discussed in general. The way in which these techniques have evolved is illustrated with an historical review of the methods adopted for a series of aircraft, arranged approximately in design chronological order.
This SAE Aerospace Information Report (AIR) has been prepared to provide information regarding options for optical control of fluid power actuation devices. It is not intended to establish standards for optical fluid power control, but rather is intended to provide a baseline or foundation from which standards can be developed. It presents and discusses approaches for command and communication with the actuation device via electro-optic means. The development of standards will require industry wide participation and cooperation to ensure interface commonality, reliability, and early reduction to practice. To facilitate such participation, this document provides potential users of the technology a balanced consensus on its present state of development, the prospects for demonstration of production readiness, and a discussion of problem areas within this technology. The intent is to inform the user/designer of the options available for interfacing photonics (optics) to hydraulic power
An advanced flight control system, which has been demonstrated to compensate for unanticipated failures in military aircraft, is proposed for use in general aviation. The method uses inverse control to decouple the flight controls and to modify the handling qualities of the aircraft, while employing artificial neural networks in order to compensate for any modeling error. These errors can stem from any differences between the model and the actual aircraft. Therefore, they can include in-flight hardware failures, rendering the system fault tolerant and reducing the necessity for multiple levels of redundancy. The proposed system is verified in simulations for longitudinal flight and is shown to be able to track pilot-commanded velocity and flight path angle. Also, one example is presented for in-flight changes of the configurations (flap deployment) where the controller is shown to adapt rapidly to these changes without a need for compensation by the pilot. A brief discussion is also
The automotive industry is moving ahead to introduce drive-by-wire (DBW) electronic systems to replace mechanical controls and linkages that have changed little since cars were first introduced. Electronic drive-by-wire systems offer enormous potential to improve vehicle performance and safety, but matching the dependability of simple mechanical components with electronics will be a challenge. Highly dependable electronic controls require a fault-tolerant approach with both a primary and a backup system as a minimum. Aircraft fly-by-wire systems go beyond this, using triple and quadruple redundant electronics to tolerate more than one failure during the same flight. Automobile drive-by-wire must also provide some capability to allow the car to be driven safely to a repair facility after a failure occurs. This paper examines some possible drive-by-wire systems architectures, presents a mathematical analysis of the predicted dependability (expressed as the probability the system will
A design method for ultra-dependable control-by-wire systems is presented here. With a top-down approach, exploiting the system's intrinsic redundancy combined with a scalable software redundancy, it is possible to meet dependability requirements cost-effectively. The method starts with the system's functions, which are broken down to the basic elements; task, sensor or actuator. A task graph shows the basic elements interrelationships. Sensor and actuator nodes form a non-redundant hardware architecture. The functional task-graph gives input when allocating software on the node architecture. Tasks are allocated to achieve low inter-node communication and transient fault tolerance using scalable software redundancy. Hardware is added to meet the dependability requirements. Finally, the method describes fault handling and bus scheduling. The proposed method has been used in two cases; a fly-by-wire aircraft and a drive-by-wire car.
This information report (AIR) provides design information of various contemporary aircraft fly-by-wire (FBW) flight control actuation systems that may be useful in the design of future systems for similar applications. It is primarily applicable to manned aircraft. It presents the basic characteristics, hardware descriptions, redundancy concepts, functional schematics, and discussions of the servo controls, failure monitoring, and fault tolerance. All existing FBW actuation systems are not described herein; however, those most representing the latest designs are included. While this AIR is intended as a reference source of information for aircraft actuation system designs, the exclusion or omission of any other appropriate actuation system or subsystem should not limit consideration of their use on future aircraft.
This SAE Aerospace Information Report (AIR) contains technical information on aerospace hydraulic, actuation and support equipment technologies lessons learned. The lessons learned were prepared by system designers and hydraulic engineers from the aerospace industry and government services as part of SAE Committee A-6, Aerospace Fluid Power, Actuation, and Control Technologies, and were presented at eight Lessons Learned Symposia from 1989 through 1999 held during A-6 Committee meetings. The technical topics represent many years of design experience in hydraulics and actuation, which it is felt is a resource for learning that should be documented and made available to current and future aerospace hydraulic engineers and designers. The document is organized into two sections: systems and components with further categories within the components section. The information topics are presented in a concise format of problem, issue, and solution, with accompanying descriptive diagrams and
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