Automatic Flight Control System Research Articles

Research on automatic flight control system flight mode operation logic

The auto-flight system of modern civil aircraft is the main man-machine interaction system, and its flight mode operation function is jointly completed by FMCP hardware and auto-flight control system software. In order to achieve a complex flight mode operation control logic design, first the hardware and software composition and specific functions of flight mode operation control are clarified. Then the flight mode operation function is refined and logically sorted out. Finally, the software and hardware models of flight mode operation control are established through Simulink. This paper verifies whether the realization of the mode operation control function meets the expectation.

Flight Guidance Concepts to Mitigate Flight Control System Degradation in Urban Air Mobility Scenarios

Continued safe flight under all foreseeable scenarios will be crucial to assure airworthiness and build trust in future vertical takeoff and landing (VTOL) urban air mobility (UAM) concepts. Successful pilot intervention will be especially important for handling emergency procedures. This paper demonstrates the use of human-centric flight guidance concepts to mitigate the effects of non-catastrophic failures in future VTOL UAM aircraft. Specifically, a single failure in the lateral steering function of an automatic flight control system is considered. A new waypoint guidance law is proposed to generate the required roll command to manually steer the aircraft toward a predefined safe landing zone. Two display concepts are proposed to aid the manual execution of the roll steering command: a head-down display (HDD), and a head-mounted display (HMD). The guidance law and the display concepts were integrated into a high-fidelity, wide field-of-view rotorcraft simulation environment. Human-in-the-loop experiments were performed with non-pilot test subjects. The effectiveness of the guidance law and display concepts along with the associated piloting performance and human factor impacts were assessed. The results indicated that all test subjects were able to reach a close vicinity of the final waypoint. The HMD induced lower workload whereas the HDD resulted in better tracking performance.

Confronting Aerotowing Experts With a New Phase-of-Flight Taxonomy for Towplanes

Abstract: While designing an automated flight control system for aerotowing gliders, engineers realized that no suitable phase-of-flight taxonomy was available for performing a functional hazard assessment. As first experiences with a custom taxonomy were gathered, questions arose on how reproducible these results were and whether they could be applied to aerotow-related tasks outside the systems engineering domain. Inter-rater agreement, as one key metric of the taxonomy, was investigated by having 13 experts on aerotowing rate a total of 30 scenarios that are presented as photographs, video sequences, and textual narratives. Agreement between experts was substantial across these types of media. The remaining sources of disagreement were found to be of little practical relevance during real-world application of the aerotowing taxonomy.

An Unmanned Helicopter Energy Consumption Analysis

The number of operations incorporating E-VTOL aircrafts is increasing each year, and the optimization of the energy consumption of such vehicles is a major problem. In this paper, a small-scale ARCHER helicopter’s energy consumption is analyzed, wherein different flight conditions, main rotor revolutions, and flight control system settings are considered. The helicopter dynamic model was developed in the FLIGHTLAB environment and was then validated based on flight test data. The model used for the calculation of energy consumption was developed using the electric and dynamic characteristics of the main rotor, electric motor, and transmission system. The main part of this work concerns the analysis of electric energy consumption during the vehicle’s flight via the use of an automatic flight control system (AFCS) that ensures repeatable flight conditions. The AFCS was designed such that it includes both path and attitude control to provide hover and cruise control modes. The helicopter’s energy consumption was analyzed during different phases of flight, when executing maneuvers, and using different main rotor angular velocities to perform - a given task. The results show that the level of energy consumption significantly depends on the helicopter’s main rotor revolutions, flight speed, and the maneuvers performed. The proposed methodology can be used in prospective energy-efficient mission planning and UAV helicopter design.

Automatic flight control: Bridging the gap between fixed-wing drones and airplanes

Over the past two decades, remotely piloted aircraft have increased significantly in size, weight, and range. As the lines blur between drone and airplane technology, engineers must reconcile conflicting assumptions and approaches when developing small drones versus conventional full-sized aircraft. This article summarizes key considerations with systems architecture, control theory, and regulatory approvals that early career engineers should be aware of when developing automatic flight control systems. Various examples including energy management, left-yawing tendencies, automatic landing systems, and machine learning applications are used to highlight the major differences therein.

Time Invariant Static Nonlinearities of the Dynamical Systems

Abstract Dynamical technical systems are famous for large scale of time invariant nonlinearities applied inside. Some kinds of nonlinearities describe physical properties of devices used in the technical system. Some special kind of time invariant static nonlinearities are for ensure stability limiting and truncating signals inside the dynamical systems. Moreover, nonlinearity is a property of materials used both in static or dynamical induction machines. One of the widely spread and applied method to handle static nonlinearities is dynamical technical systems is the describing function method (DFM). The purpose of the author is to introduce and apply this technique to evaluate stability conditions of the automatic flight control system of the unmanned aerial vehicles (UAVs).

Model-based microburst identification using a hybridized extended Kalman filter with genetic algorithm

Microburst (MB) wind shear is one of the most important meteorological dangers threatening the aircraft (AC) safety and the life of passengers. Though there are some ground-based 3D Lidar systems to detect low-level MB wind shears to alert the pilots, there have been fewer scientific attempts to identify model-based MB parameters via AC onboard air and position data. The latter refers to the development and identification of an acceptable MB model upon which an automatic flight control (AFC) system can be designed to control the AC through wind shear microburst. In essence, accurate knowledge of MB model is an essential prerequisite for design and analysis of AFC systems that can safely fly the AC against microbursts, especially in crucial phases of flight such as takeoff and landing. The present study focuses on online estimation of MB parameters whose results pave the way for effective MB autopilot designs for safe flights through MB. The proposed task is accomplished via a model-based approach using the AC six degrees of freedom (6 DoF) equations of motion (EOM) integrated with the latest verified model of the MB utilizing the extended Kalman filter (EKF). In addition to a sensitivity analysis to determine the key MB model parameters, the performance of the estimation process is enhanced via a hybridization of the genetic algorithm (GA) with the EKF. The results are promising and indicate that the proposed scheme can identify the MB model parameters with sufficient accuracy needed for online applications with AFC design.

Flight Dynamics and Control of an eVTOL Concept Aircraft with a Propeller-Driven Rotor

The objective of this investigation is threefold. First, to assess the flight dynamics of an electric vertical take-off and landing (eVTOL) concept aircraft with a propeller-driven rotor. Second, to develop an automatic flight control system (AFCS) for this concept aircraft. Third, to verify the potential safety benefits of the concept aircraft by analyzing the autorotation performance following a total loss of power. The paper begins with an overview of the design of the aircraft and description of the simulation model, including a detailed discussion on the inflow model of the propellers that drive the main rotor. Next, the flight dynamics are assessed at hover and in forward flight. An AFCS based on dynamic inversion is developed to provide stability and desired response characteristics about the roll, pitch, yaw, and heave axes for speeds ranging from hover to 80 kt. Additionally, an RPM governor is implemented to hold the main rotor angular speed constant at its nominal value. Finally, simulations that make use of the AFCS are performed to analyze the autorotation performance following total loss of power.

The PAPI Lights-Based Vision System for Aircraft Automatic Control during Approach and Landing

The paper presents the concept of a component of an aircraft’s automatic flight control system, controlling the airplane when in longitudinal motion (i.e., pitch angle, sink rate, airspeed channels) during automatic landing, from a final approach until a touchdown. It is composed of two key parts: a vision system and an automatic landing system. The first part exploits dedicated image-processing algorithms to identify the number of red and white PAPI lights appearing on an onboard video camera. Its output data—information about an aircraft’s position on a vertical profile of a landing trajectory—is used as one of the crucial inputs to the automatic landing system (the second part), which uses them to control the landing. The control algorithms implemented by the automatic landing system are based on the fuzzy logic expert system and were developed to imitate the pilot’s control actions during landing an aircraft. These two parts were teamed together as a component of a laboratory rig, first as pure software algorithms only, then as real hardware modules with downloaded algorithms. In two test campaigns (software in the loop and hardware in the loop) they controlled an aircraft model in a simulation environment. Selected results, presenting both control efficiency and flight precision, are given in the final section of the paper.

Research and Design of Automatic Flight Control System Test System

Research and Design of Automatic Flight Control System Test System

KUH-1 자동비행 조종시스템으로 유발된 조종사의 Complacency와 비행 수행도

Objective: The aim of this study is to provide experimental evidence for the problem of complacency when using the AFCS (Automatic Flight Control System) of KUH-1 and suggest ways to prevent it.<BR>Background: With the introduction of the modern cockpit automation systems, the risk of complacency effect has increased. Many studies have been conducted on the complacency, but no experimental studies have investigated the complacency in the actual aviation domain using autopilot. In this study, the impact of trust and expertise on monitoring behavior and the impact of monitoring behavior on flight performance are investigated. Automation induced complacency is inferred as a consequence of monitoring behavior.<BR>Method: In the KUH-1 simulator, 19 pilots flew in the traffic pattern. During the flight, monitoring behavior data were collected with an eye-tracker, and flight performance was measured by whether to be off course and the action time in case of AFCS failure. Trust in AFCS was measured by a questionnaire.<BR>Results: Trust in AFCS did not affect monitoring behavior in the entire sample. But trust induced different monitoring behavior depending on the expertise. Pilots who were off course focused longer on the secondary task at once. The action time in AFCS failure was significantly related to the proportion of total dwell time in the secondary task and the pilots

The Design of an Automatic Flight Control System and Dynamic Simulation for Fixed-Wing Unmanned Aerial Vehicle (UAV) using X-Plane and LabVIEW

This research focuses on developing an automatic flight control system for a fixed-wing unmanned aerial vehicle (UAV) using a software-in-the-loop method in which the PID controller is implemented in National Instruments LabVIEW software and the flight dynamics of the fixed-wing UAV are simulated using the X-Plane flight simulator. The fixed-wing UAV model is created using the Plane Maker software and is based on existing geometry and propulsion data from the literature. Gain tuning for the PID controller is accomplished using the pole placement technique. In this approach, the controller gain can be calculated using the dynamic parameters in the transfer function model and the desired characteristic equation. The proposed controller designs' performance is validated using attitude, altitude, and velocity hold simulations. The results demonstrate that the technique can be an effective tool for researchers to validate their UAV control algorithms by utilising the realistic UAV or manned aircraft models available in the X-Plane flight simulator.

Development of an Embedded Longitudinal Flight Control Based on X-Plane Flight Simulator

Avionics is a category of electronic systems, equipment and instruments specifically designed for use in aviation. Usually called autopilot, the Automatic Flight Control System, is one of the main systems in avionics. Autopilot systems are designed to automatically control the aircraft piloting, reducing the pilot fatigue caused by the flight. Before being embedded into an aircraft, an autopilot system must be exhaustively evaluated by computational simulations to be validated. The objective of this work is to describe the development of an embedded automatic flight controller aimed to be applied to a Cessna-172SP-Skyhawkmodel aircraft in order to control its altitude. The developed flight controller is based on a tuned PID control and it is embedded in a Raspberry Pi that actually controls the altitude of the aircraft simulated in the X-Plane 11 flight simulator, running on a Desktop PC connected by UDP to the Raspberry Pi. The simulation results validated the proposed flight controller as well as the proposed hardware scheme for validation.

Impact of actuators backlash on the helicopter control during landing on the moving vessel deck

PurposeThe purpose of this paper is to test the performance of the control system developed for the helicopter automatic approach and landing on the moving vessel deck, when different values of backlashes are applied to the four control actuators.Design/methodology/approachThe system consists of automatic control algorithm based on the linear quadratic regulator and the vessel motion prediction algorithm based on autoregressive method with parameters calculated using Burg’s method. Necessary navigation data is provided by on-board inertial navigation system/Global Positioning System. Calculated control commands are executed by four electromechanical actuators. Performance of the mission, which is based on selected procedure of approach and landing of the helicopter on the moving vessel deck, is analyzed taking into account different values of backlashes applied to the actuators.FindingsIn this paper, a description of the control system dedicated for automatic approach and landing of the helicopter on the moving vessel deck is shown. Necessary information about helicopter dynamic model, control system and vessel motion model is included. Tests showing influence of actuator backlashes on the mission performance are presented.Practical implicationsThe developed control methodology can be adapted for selected helicopter and used in prospective development of an automatic flight control system (AFCS) or in a simulator. The system can be used to define in which conditions helicopter can perform safe and successful automatic approach and landing on a moving vessel deck.Originality/valueIn this paper, an integrated control system is presented; influence of the control actuator backlashes on the mission performance is analyzed.

Regaining Loss in Dynamic Stability after Control Surface Failure for an Air-Breathing Hypersonic Aircraft Flying At Mach 8.0

The aim of the study is to reconfigure the automatic flight control systems of a hypersonic vehicle so that dynamic stability can be restored when flight control fails. LQR theory is used to first find the feedback gain when all 3 flight control systems are working. Failure was simulated one at a time to investigate lost in dynamic stability. When instability occurs, the new gains are obtained for the remaining flight controls using a modified Minimum Principal theory. The simulations show that the dynamic stability can be restored using these new reconfiguration gains if any one of the 3 flight control systems fail at one time but not in combination. The failure of elevator flaps at hypersonic speeds is likely due to aerodynamic heating. It is shown that the engine diffuser and the temperature across combustor controls can regain longitudinal dynamic stability to at least slow down the aircraft to safety. Study is limited to longitudinal motion only.

Aircraft Flight Stabilizer System by CDM Designed Servo State-Feedback Controller

This research presents an automatic flight control system whose advantage is its ease of modification or maintenance while still effectively meeting the system’s performance requirement. This research proposes a mixed servo state-feedback system for controlling aircraft longitudinal and lateral-directional motion simultaneously based on the coefficient diagram method or CDM as the controller design methodology. The structure of this mixed servo state-feedback system is intuitive and straightforward, while CDM’s design processes are clear. Simulation results with aircraft linear and nonlinear models exhibit excellent performance in stabilizing and tracking the reference commands for both longitudinal and lateral-directional motion.

Algorithmic support of low-altitude aircraft flight based on the hazard analysis of the flight situation

Low-altitude flight of an aircraft is an effective, but at the same time, a very complex tactical technique, during which the crew does not always have the opportunity to timely recognize the occurrence of an abnormal case, determine the way out of it and counteract an aviation accident development. Despite many advantages of the automatic mode of low-altitude flight performing, its practical implementation is associated with a number of features and disadvantages, which determined the preference for the manual mode of low-altitude flight control. These are the presence of telltale factors, limited ability of performing flights at night and in difficult weather conditions, insufficient reliability etc. The considered features determined the relevance of the of low-altitude flight safety ensuring problem in relation to the manual control mode. As a result of an experimental study of the low-altitude flight performing process in a manual control mode, it was found that when performing manually-controlled low-altitude flight, a hazard assessment of the flight situation becomes pivotal. However the crew being under such conditions is not always able to correctly assess the flight situation hazard due to a combination of objective reasons. The current state of the adaptive and on-board flight safety systems theory makes it possible to increase the safety of the manuallycontrolled low-altitude flight by using adaptive control algorithms based on the flight situation hazard assessment. To solve this problem an adaptive control algorithm is proposed that ensures the formation of a security corridor in the longitudinal control channel, where the upper limit is determined by the critical value of the aircraft detection hazard, and the lower limit is determined by the critical value of the error in maintaining a given flight altitude. For a continuous assessment of the flight situation hazard and the timely formation of control signals the complex information about the current true flight altitude and the foreground is needed. Taking into account the peculiarities of low-altitude flight a digital terrain map containing data on natural and artificial obstacles along the flight route is a more rational source of information, that will make it possible to predict the development of the flight situation hazard. The above reasoning makes it possible to form an aircraft low-altitude flight adaptive control algorithm. A distinctive feature of the proposed algorithm is the implementation of a combined control variety where the pilot is provided with ample manual control opportunities within the security corridor, and the automatic flight control system is assigned the role of a safety subsystem that ensures control and timely return of the flight situation to normal flight conditions. The presented algorithm will allow to increase the crew logical-analytical activity information support during continuous analysis of the existing flight situation due to the formation of protective control actions based on the current flight situation hazard analysis.

Study of Unmanned Aerial Vehicle Flight Capabilities in the Aspect of Civil and Military Aviation Safety

The article discusses the issues related to the adaptation of flights performed by military unmanned aerial vehicles in Poland (Unmanned Aerial Vehicle – UAV) to the civil aviation requirements. The unmanned aerial vehicles’ flight capabilities were discussed from the perspective of using the automatic flight control system to minimise a threat to civil and military aviation. Owing to the growing interest of the European Union (EU) in unmanned systems, there are many threats related to the broadly understood traffic safety in the European airspace.

Understanding the Effect of Rotor-to-Rotor Interference on CH-47D Helicopter Dynamics

During the development of the Boeing CH-47D helicopter flight simulation model, test pilots reported mismatch between the flight simulator results and flight test data of the hover and low-speed lateral axis handling qualities, especially for the case without the automatic flight control system. In addressing the observed mismatch, the gains of the longitudinal and lateral components of the inflow model were selected to be significantly higher than their theoretical values. In this study, a detailed understanding of the rotor-to-rotor inflow interference is pursued using a recently developed multi-rotor pressure potential superposition inflow model. It is shown that the coupling between the inflow gradients of individual rotors exists in a tandem rotor, which can be approximated by using higher values for the longitudinal and lateral inflow gains of individual rotors. Further, it is shown that the need for empirical tuning of aerodynamic hub moment influence factors can be eliminated by properly accounting for the rotor-to-rotor interference in the inflow model.

RELIABILITY LEVEL ON AFCS ACTUATOR COMPONENT OF THE SIKORSKY S-76 HELICOPTER

The use of helicopters is very useful for Indonesia's natural conditions which is in the form of islands. In order to support the helicopter's capabilities, an AFCS actuator or automatic flight control system actuator is needed to make the flight automatically. Therefore, the author tries to conduct a reliability analysis to determine the level of reliability of the AFCS Actuator component in S-76 helicopter. The method used to conduct the analysis is the Weibull distribution method, which is one of several methods that are often used. The main objective is to determine the level of reliability and characteristics of the failure modes that often occur in these components. By analyzing at the results of calculations and types of failures, it can be seen the types of effective treatments to be applied to the AFCS Actuator component.