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In order to automate the ground maneuvering of a civil regional aircraft and improve the efficiency of the air transport system, a fly-by-wire nose wheel steering system (NWSS) was designed. A rack and pinion steering mechanism integrated with a single actuator mechanism was proposed. The basic control circuit diagram with integrated test, the electro-hydraulic system diagram, and the mathematical model of the steering system were established and analyzed. A co-simulation model of the system was built to verify the control law. The results show that the properties of the prototype meet the design requirements. Given the importance of the NWSS, the simulation results can be used to optimize the basic design parameters. This methodology can also be used for other types of aircraft. [ABSTRACT FROM AUTHOR]

This report shows the execution and evolution of airplane flight control systems. The report describes the development of airplane flight control systems and gives a survey of the principal phases of the flight control systems that assure the finding and execution of the fly-by-wire system. The development of flight control systems, from human control with mechanical links to a wire-driven computer, is a remarkable representation of the development of aeronautical technologies. The fly-by-wire system constitutes a fast-forwarding in aircraft design, from mechanical linkage to large hydraulic actuators to computer-assisted fly-by-wire system. The use of the fly-by-wire system has generated huge satisfaction for the aircraft industry by lessening the weight of the flight control system, by creating multiple redundancy flight control systems, which increases the flight safety of all aircraft equipped with the fly-by-wire system. The passage from analog to digital is another fast-forwarding in the development of fly-by-wire systems.

In this paper, the results of research on additively manufactured aerospace parts made of maraging steel are presented. This state-of-the-art technology seems to have the highest potential for practical use in the field of ultra-light and high-performance aerospace hydraulic parts. The strength properties of representative specimens made with steel 1.2709 were investigated. The researchers conducted static tensile testing, fatigue tensile testing, and pressure impulse testing. A Goodman diagram was plotted to visualize the impact of the building orientation vs. load character on the fatigue strength of the additive manufacturing (AM) specimens. Based on the research carried out on the strength of the AM samples, an aircraft flight control actuator was designed to achieve the highest level of safety integrity along with the greatest simplicity and lowest weight relative to hydraulic actuators manufactured using classical methods. The entire design process was integrated with the manufacturing process to achieve this target. [ABSTRACT FROM AUTHOR]

This paper focuses on force-fight oscillation mitigation in fly-by-wire (FBW) flight control systems (FCSs) for civil aircraft. The theory of "force fight" was first introduced after analyzing its impact on active-active actuators system. The architecture of one typical FBW FCS and the layout of an electronic hydraulic servo actuator (EHSA) were described. A force-fight mitigation algorithm applying pressure and position compensation feedback was then presented. To validate algorithm performance, an associated actuator-surface model was created to simulate force fight. Finally, the algorithm was tested using worst-case scenarios by calculating the system latency and tolerance, and verified using special ''Iron Bird'' tests. The results show an obvious decrease in the difference delta press (DDP) when comparing with/without mitigation, and thereby meeting force fight limitation requirements. [ABSTRACT FROM AUTHOR]

This report shows the execution and evolution of airplane flight control systems. The report describes the development of airplane flight control systems and gives a survey of the principal phases of the flight control systems that assure the finding and execution of the fly-by-wire system. The development of flight control systems, from human control with mechanical links to a wire-driven computer, is a remarkable representation of the development of aeronautical technologies. The fly-bywire system constitutes a fast-forwarding in aircraft design, from mechanical linkage to large hydraulic actuators to computer-assisted fly-by-wire system. The use of the fly-by-wire system has generated huge satisfaction for the aircraft industry by lessening the weight of the flight control system, by creating multiple redundancy flight control systems, which increases the flight safety of all aircraft equipped with the fly-by-wire system. The passage from analog to digital is another fast-forwarding in the development of fly-by-wire systems. [ABSTRACT FROM AUTHOR]

Oscillatory failure cases (OFC) detection in the fly-by-wire (FBW) flight control system for civil aircraft is addressed in this paper. First. OFC is ranked four levels: Handling quality, static load, global structure fatigue and local fatigue, according to their respect impact on aircraft. Second, we present voting and comparing monitors based on un"similarity redundancy commands to detect OFC . Third, the associated performances, the thresholds and the counters of the monitors are calculated by the high fidelity nonlinear aircraft models. Finally, the monitors of OFC are verified by the Iron Bird Platform with real parameters of the flight control system. The results show that our approach can detect OFC rapidly. [ABSTRACT FROM AUTHOR]

Maintenance of flight control actuation systems is currently performed on a scheduled basis, however air fleet operators and component manufacturers are willing to move from scheduled maintenance to Condition Based Maintenance (CBM) in order to reduce maintenance costs and improve aircraft dispatchability. Prognostics and Health Management (PHM) systems are a critical part of CBM and are perceived as a breakthrough technology to effectively respond to an urgent and critical need to improve the readiness, availability, reliability, safety and maintainability of aerospace vehicles. This paper presents the results of an ongoing research activity focused on the development of a PHM system for fly-by-wire Electro-Hydraulic Servo Actuators (EHSA) without adding new sensors. The PHM system is being developed with the objective of detecting the most common faults, according to a failure mode effects and criticality analysis (FMECA). The paper describes in particular the tools used for detection and tracking of internal leakage faults of the hydraulic actuator, which is one of the most common faults of hydraulic servo-actuators in service, and for predicting its remaining useful life (RUL). The research work has been supported by the development of a nonlinear model for a reference EHSA, that has been implemented using physical equations and system parameters, taking into account environmental condition and disturbances. The model was validated through tests runs on a flight control actuator of a civil aircraft. Simulations are performed in nominal conditions and with progressive injection of degradation to verify the PHM algorithm. The performances of the PHM algorithms are evaluated by means of proper metrics. [ABSTRACT FROM AUTHOR]

Aircraft damage modelling was conducted on a Boeing 747 to examine the effects of asymmetric horizontal stabiliser loss on the flight dynamics of a commercial Fly-by-Wire (FBW) aircraft. Robustness of the control system is investigated by analysing how characteristic eigenvalues move as a result of damage and comparison to the non-FBW aircraft is made. Furthermore, the extent of stabiliser loss that the system can successfully handle without loss of stability and acceptable performance is identified. The presented analysis of the results gives insightful knowledge to aid in the design of an improved FBW system with increased damage tolerance. A handling qualities evaluation is presented to provide an understanding of how the pilot perceives the damaged aircraft. The results of the study show that a generic FBW system improves robustness such that the aircraft is stable with 50% horizontal stabiliser loss. With 50% damage, the aircraft is controllable but unsafe to fly and may be unable to effectively complete its mission task. [ABSTRACT FROM PUBLISHER]

Safety critical systems are the systems which may lead to hazards, loss of lives and great damage to the property if they fail due to errors which may lead to faults. It's important for a variety of reasons that safety critical systems execute without errors, and we always expect the system must work under any situation. There are different domains in which systems are used that we focused on the biomedical robots and fly by wire systems. A biomedical system is one which interfaces with humans in a medical context. Fly-by-wire (FBW) is a system that replaces the conventional manual flight controls of an aircraft with an electronic interface. This paper presents a layered fault tolerance framework for safety critical systems. Triple Modular Redundancy (TMR) method with weighted average voter and Genetic Algorithm (GA) is used in the sensor section. A voter circuit of the TMR will choose one of three sensor output to be processed further. Application of TMR will tolerate faults in the sensor section. The performance of voting algorithm is computed through a series of fault injection experiments and the results are compared with weighted average voting algorithms. The obtained results of simulating using MATLAB showed that the suggested algorithm gives better safety in comparison to the studied voting algorithms. Therefore, it's the best option for using in the fault tolerance of medical robots and fly-by-wire systems. [ABSTRACT FROM AUTHOR]

This paper is aimed at the differences between the control systems on commercial aircraft. Architecture of the particular control systems is given a closer look and in this way based on the analogy method of control system of commercial aircraft we can apply this knowledge of control systems to flight laboratories of the University of Žilina, which are the part of project “Centre of Excellence for Air Transport” ITMS 26220120065.

A CAN data bus was used in a project of an experimental Fly‐by‐Wire control system (SPS‐1) mounted on board a PZL‐110 “Koliber” general aviation aircraft. This solution allows the free communication between flight control computers and individual modules of the system. The monitoring of the bus state and data frames is useful during particular hardware tests, system integration, laboratory and in‐flight tests. This report intends to present the specific monitor tool developed with the to SPS‐1. The main part of the CAN monitoring system is software. It realizes acquisition, visualization and conversion of stored data. The monitoring software operates with devices used by an experimental control system and connected to the bus. Particular devices are assigned to separate windows. The operator can control the SPS‐1 system through specialized windows or by virtual cockpit. Apart from this, the CAN monitor controls and simulates selected modules of the SPS‐1 system and works as the bus diagnostics tool. First Published Online: 14 Oct 2010

Light general aviation airplanes become more affordable means of transport for the still raising group of people. This fact brings few consequences, of course. One of them is a set of problems appearing when inexperienced pilots start using such planes. Their habits and reactions to external factors are different to behaviors of professional pilots. So it seems to be purposeful to create the control system adequate to expectations of this group of pilots. First published online: 14 Oct 2010

The development of informatics and sensor techniques has extended the possibilities of flight parameter measurement. It allows for extensive modification of control and navigation systems in air vehicles. This advance can also be noticed in the research of the Department of Avionics and Control at the Faculty of Mechanical Engineering and Aeronautics, Rzeszow University of Technology. Research in the area of digital flight control systems was initiated at the Department of Avionics and Control over twenty years ago. First published online: 14 Oct 2010

Fly‐by‐wire systems enable superior control of chosen flight parameters. A pilot can modify stabilized parameters by adequate movement of control inceptors such as a side‐stick or trust lever. Fly‐by‐wire control reduces the load on a pilot and allows a pilot to focus on the main tasks. Unfortunately, the use of more complicated interfaces between human and machine can cause incorrect pilot behavior and in many cases lead to erroneous interactions between the operator and effective aircraft dynamics. The structure of control laws and dynamics of electromechanical actuators are especially important factors. They can influence unfavorable aircraft‐pilot coupling and can lead to pilot‐induced oscillations (PIO) in certain cases. The automatic detection of PIOs is presented in this paper. The practical realization of a PIO‐detector and examples of diagnostics of human‐machine systems are reported on in this article. First published online: 14 Oct 2010

The Fly‐by‐Wire technology enables flexible shaping of both effective dynamics and handling qualities of aircraft. This solution extends aircraft possibilities and supports the pilot by use of high‐level control laws. Application of FBW for aircraft would make flying both safer, and more popular. On the other hand the FBW system must be highly reliable. Advanced indirect flight control technology requires the use of actuators characterized by fault tolerant architecture. It should enable improvement of reliability of the aircraft control system and safety of performed flights effectively. The Electromechanical Actuator (EMA) consists of the electric motor, gearbox and controller. The actuator controller should be made intrinsically reliable and should be insensitive to other equipment failure. The conception of fault tolerant control algorithms as well as practical realization of it has been presented in this work. Tests of reliability of the complete EMA unit have also been presented herein. First published online: 14 Oct 2010

A long‐term goal for general aviation aircraft is to reduce or eliminate the use of fluid power systems such as hydraulics from the aircraft. Power‐By‐Wire (PBW) technology seems to be the next major step in the development of aircraft control. In this solution, control power comes directly from the aircraft electrical system to the Electro‐Mechanical Actuator (EMA), which includes the electric motor, controller and gearbox. EMAs have the potential to be more efficient, less complicated, less expensive, and more faults tolerant than actuators based on hydraulic systems. First Published Online: 14 Oct 2010

To improve the airfield performance, the aircraft landing gear is gradually developed to use the fly-by-wire system at present. To meet the demand for the motion with low speed and large angle, and the large steering moment, most of the modern large civil aircraft are equipped with dual actuator nose wheel steering system. Aiming at the dual actuator nose wheel steering system with fly-by-wire on large civil aircraft, a swivel selector valve is firstly designed to meet the demand for the hydraulic power commutating as soon as the dual actuator nose wheel steering mechanism passing through its dead center position, then based on the steering and operating demand of the dual actuator nose wheel steering system, a nose wheel steering electro-hydraulic servo system is designed, which has the functions of steering with large angle and low speed by hand wheel, steering with small angle and high speed, and anti-shimmy. For the verification of the system steering and shimmy damping function, its simulation model is established to make dynamic simulation analysis, whose results indicate that the nose wheel steering system can meet the requirements of the general project. [ABSTRACT FROM AUTHOR]

The paper deals with the study of the temperature effects on the performances of fly-by-wire hydraulic actuators. The activity is developed via both experiments and simulations, using a primary flight actuator of a modern fly-by-wire jet trainer as reference hardware. A dedicated experimental set-up is arranged, by integrating a thermal chamber with a real-time actuator control system developed in the MATLAB-Simulink-xPC Target environment, and an extensive test campaign is performed on the actuator in environmental control conditions. In particular, both the static and the dynamic performances are concerned, characterizing the valve threshold, the valve motor gain, the open-loop, and closed-loop frequency responses. The tests are performed at ambient, extreme hot (71 °C), cold (−20 °C), and extreme cold (−40 °C) temperatures. Experimental results are reported and discussed, providing a physical interpretation of temperature sensitivity effects. Concerning the simulation studies, they started from a detailed model of the actuator dynamics, previously developed and validated by the author at ambient temperature. The model is adapted for taking into account the temperature effects, and an experimental validation is obtained at servovalve level. The influence of temperature at actuator level is predicted by simulation, highlighting and discussing the expected closed-loop control concerns. [ABSTRACT FROM AUTHOR]