Carrier-based Aircraft Landing Research Articles

Adaptive terminal sliding combined super twisting control design and flight tests for automatic carrier landing system

Considering the challenges posed by external disturbances on carrier-based aircraft landing control, higher demands are required for the precision and convergence of the carrier landing control system. First, this paper proposes an Adaptive Terminal Sliding Combined Super Twisting Control (ATS-STC) method to address the issues of low precision, slow convergence, and poor disturbance rejection capability resulting from external disturbances, such as carrier air-wake and deck motion. By introducing a nonlinear term into the sliding surface and employing an integral approach, the proposed ATS-STC method can ensure finite-time convergence and mitigate the chattering problem. An adaptive law is also utilized to estimate the external disturbances, thereby enhancing the anti-disturbance performance. Then, the stability and convergence time analysis of the designed controller are conducted. Based on the proposed method, an Automatic Carrier Landing System (ACLS) is developed to perform the carrier landing control task. Furthermore, a multi-dimensional validation is carried out. For the numerical simulation test, the Terminal Sliding Mode Control (TSMC) method and Proportion Integration Differentiation (PID) method are introduced as comparison, the quantitative assessment results show that the tracking error of TSMC and PID can reach 1.5 times and 2 times that of the proposed method. Finally, the Hardware-in-the-Loop (HIL) test and real flight test are conducted. All the experimental results demonstrate that the proposed control method is more effective and precise.

Modeling the Transient Dynamics of Arresting Hooks and Cables through the Parameter Inversion Method

Arresting gear systems play a vital role in carrier-based aircraft landing. In order to accurately understand the process of arresting hook and cable, this study introduces a parameter inversion method to model the arresting cable and applies it to the transient dynamics model of the arresting hook and cable. The feasibility of the arresting cable model and its application to the transient dynamics model of the arresting hook and cable are validated through arresting hook and cable impact tests. The study compares three different models of arresting cables for simulation results and concludes that assuming the arresting cable to be a beam with metal elastic parameters during the modeling process cannot ignore the influence of the cable’s torsional and bending stiffness on the modeling. The study also investigates the dynamic response of the arresting hook during the aircraft arrestment and hooking process and concludes that the stress peak of the hook arm is much lower throughout the entire arrestment process than at the moment of hooking the cable. The study further identifies factors that affect the stress on the arresting hook arm, such as the aircraft’s yaw angle, deck angle, cruising speed, and the initial position of the arresting hook and cable before engagement. The research results have significant implications for improving the design optimization of the structural strength of the functional components of the naval aircraft arresting system and provide theoretical guidance and technical reserves for subsequent related studies.

Fault-Tolerant Control for Carrier-Based Aircraft Based on Adaptive Fuzzy Sliding-Mode Method

Carrier-based aircraft landing involves complex system engineering characterised by strong nonlinearity, significant coupling and susceptibility to environmental disturbances, and autonomous landing of carrier-based aircraft under fault states is even more challenging and riskier. To address the control-system problems of loss of efficiency and performance due to actuator faults and performance degradation due to various unknown disturbances, presented here is fault-tolerant control for carrier-based aircraft based on adaptive fuzzy sliding-mode fault-tolerant control (AFSMFTC). First, three models are built (the carrier-based aircraft fault model, the carrier air wake model and the deck motion model), and the control framework of the autonomous landing control system is introduced. Next, a longitudinal and lateral flight channel controller comprising an adaptive fuzzy network, adaptive laws and a sliding-mode controller is designed using the AFSMFTC method. The adaptive fuzzy network implements fuzzy approximation for the sliding-mode switching terms to further offset errors induced by unknown disturbances, the adaptive laws compensate for actuator faults, and the sliding-mode controller ensures tracking of the overall flight path. Furthermore, the stability of the fault-tolerant method is demonstrated using the Lyapunov function. Finally, simulation and comparative experiments show that the proposed fault-tolerant method has outstanding control performance and strong fault-tolerant capability, thereby providing an effective and feasible solution for designing an autonomous landing system for carrier-based aircraft under fault states.

Automatic landing of carrier-based aircraft based on a collaboration of fault reconstruction and fault-tolerant control

Considering the actuator faults that occur during the automatic landing of carrier-based aircraft, a novel automatic landing method based on a collaboration of fault reconstruction and fault-tolerant control is proposed. The variables of the aircraft states and actuator fault are combined as a new state, and an extended state observer (ESO) is constructed to establish the deviation-based observation equation. A fault-tolerant control law based on state feedback is designed and a closed-loop control system of carrier-based aircraft landing is established. A new collaborative control algorithm is proposed based on the extended state observer and fault-tolerant control law, which solves fault reconstruction with unknown parameters and fault-tolerant control simultaneously, so that the fault estimation and control with actuator fault are decoupled. The linear matrix inequality (LMI) is utilized to complete the specific calculation. The effectiveness of the proposed collaborative algorithm is verified through the different simulations with other compared algorithms under the condition of airwake disturbance and sensor noise. The simulation curves and experiment data further demonstrate the proposed algorithm exhibits better fault estimation and automatic landing control performance.

Structural Optimization of AerMet100 Steel Torsion Spring Based on Strain Fatigue

The torsion spring of a carrier-based aircraft landing gear is a key component, which is normally manufactured out of AerMet100 ultra-high-strength steel. The takeoff and landing performance is greatly influenced by its bearing capacity and structural durability. To carry out the structure anti-fatigue design, it is necessary to investigate the influence of the spring structure features on its fatigue life, based on which the strain fatigue analysis and parameter optimization design of the torsion spring are executed. Through the finite element analysis conducted with ABAQUS, it was determined that there exists serious stress concentration in the relief groove. Based on the theory of strain fatigue, the fatigue life of the torsion spring was obtained, and the fracture position and lifecycle were consistent with the test results. A structure optimization platform based on a parametric method was established. Samples were selected through the DOE (design of experiment), and a surrogate model was established based on RBF (radial basis functions), followed by optimization using MIGA (multi-island genetic algorithms). With the parameter optimization of the relief groove, the structure was reconstituted and reanalyzed. From the simulation results, the peak strain was reduced by 30.7%, while the fatigue life was increased by 86.2% under the same loads and constraints. Moreover, laboratory tests were performed on the torsion spring after reconstruction, which showed that the fatigue life increases by 85.6% after optimization. The method presented in this paper can provide theoretical support and technical guidance for the application and structural optimization of ultra-high-strength steel structures.

Elman Neural Network-Based Direct Lift Automatic Carrier Landing Nonsingular Terminal Sliding Mode Fault-Tolerant Control System Design.

The purpose of this paper is to develop the control system using the Elman neural network (ENN) and nonsingular terminal sliding mode control (NTSMC) to improve the automatic landing capability of carrier-based aircraft based on direct lift control (DLC) when subjected to carrier air-wake disturbance and actuator failure. First, the carrier-based aircraft landing model is derived. Then, the NTSMC is proposed to ensure the system's robustness and achieve accurate trajectory tracking performance in a finite time. Due to the inclusion of nonsingularity in NTSMC, the steady-state response of the control system can be effectively improved. In addition, the ENN is derived using an adaptive learning algorithm to approximate the actuator faults and system uncertainties. To further ensure the accurate tracking of the ideal glide path by the carrier-based aircraft, the NTSMC system using an ENN estimator is proposed. Finally, this method is tested by adding different types of actuator failures. The simulation results show that the designed longitudinal fault-tolerant carrier landing system has strong robustness and fault-tolerant ability and improves the accuracy of carrier-based aircraft landing trajectory tracking.

Research on longitudinal dynamics safety boundary of carrier-based aircraft arresting

The carrier-based aircraft landing and arrest process is complex and nonlinear, and includes the coupling effect between the aircraft and the arresting system. This process has many uncertain factors, which create difficulties in landing safety analysis. To improve the accuracy and effectiveness of landing safety analysis, this paper presents some studies. Selecting a certain type of carrier-based aircraft as the research object, a dynamic model of the collision and rebound of the arresting hook was established, and the accuracy of the model was verified using laboratory test results. Subsequently, a dynamic model of the arresting hook following the engagement of the arresting cable was established, and the ideal contact area of the arresting hook was obtained by combining it with the dynamic constraint equation. Afterward, the longitudinal safety envelope of carrier-based aircraft during landing and arrest, which is the set of all states where the aircraft can safely land and arrest, was obtained based on a numerical iteration method. In addition, a reasonable safety evaluation index is proposed to quantitatively analyze the effect of the key parameters, including the sinking velocity, pitch angle and horizontal velocity, on landing and arrest safety. Based on the response surface method (RSM), the effects of the structural parameters of the landing gear on the safe envelope are discussed, and meaningful conclusions are obtained. This analysis method and its results provide a reference for top-level parameter design of carrier-based aircraft and safety research on arresting systems.

Amplitude and Phase Computable Ocean Wave Real-Time Modeling with GPU Acceleration

The CBATS (carrier-based aircraft take-off and landing training system) is an important application of virtual reality technology in the simulation field. Large-scale, real-time ocean simulations are the biggest challenge to the authenticity of the visual system of CBATS and are also currently the main research hotspot in the field of computer graphics. In this paper, a hybrid Ocean Modeling Method based on wavelet transform is presented. This method introduces an accurate phase calculation and a wind-field model solution to compensate for the randomness of wave generation and the lack of physical mechanism in spectral methods. The computational cost is greatly reduced by using a rough spatial grid to calculate the amplitude and phase values at any point in space, which effectively avoids Nyquist–Shannon Theorem limitations caused by the numerical solutions of PDEs (partial differential equations), and a high-fidelity simulation of high frequency, detailed sea surface and coherent phase-dependent wave effects is achieved. Practical verification shows that the method can fully meet the real-time simulation training requirements of CBATS with a strong real-time performance and good stability. Thus, it could play a significant role in improving the performance of the visual system.

Research on lateral dynamics safety margins of carrier-based aircraft arresting

AbstractFor the safety problems caused by the limited landing space of the deck during the arresting process of the carrier-based aircraft, a dynamic model of the carrier-based aircraft’s landing and arresting is built. Based on the batch simulation method, the lateral dynamics safety envelope of the aircraft during the arresting was defined, and the dynamic response of the key points in the envelope during the arresting process was investigated. Subsequently, the influence of engine thrust and aircraft quality on the arresting safety envelope was studied based on reasonable safety evaluation indicators, and the safety status envelope of the deck arresting was given. Then, the particular Hamilton-Jacobi partial differential equation is used to obtain the lateral dynamics safety envelope of the carrier-based aircraft in the process of landing and arresting by backward inversion. Results indicate that engine thrust and landing quality have little effect on the yaw angle in the arresting safety boundary during the arresting. Additionally, with the engine thrust and landing quality increase, the maximum safe off-centre distance gradually decreases, and the safety boundary decreases accordingly. During the phase of landing glide, the engine thrust and quality have little effect on the maximum safe eccentric distance. When the engine thrust is increased by 40%, the maximum safe yaw angle is reduced from 0.3°, and the safety boundary is reduced by 4.2%. When the aircraftquality increases by 40%, the maximum safe yaw angle is reduced by 0.4°, and the safety boundary is reduced by 2.8%. The findings of this paper can provide framework for the research on theaircraft-to-carrier dynamic matching characteristics of the carrier-based system, and is of great significance to the research on improving the safety of the carrier-based aircraft landing arresting.

Risk Analysis of Complex System Operation considering Effective Control Time

The fresh new traits that new equipment possesses, such as the high complexity of complex equip-processing, the multiformity of the equip-used environment, the coupling characteristic of the human-equipment-environment factors, and the dynamic idiosyncrasy of risk, bring huge challenges to the safety analysis and evaluation. According to the characteristics of a complex system, such as hierarchy, structure, and complex operating environment, this paper analyzes and depicts the state evolution process of equipment from hazard symptoms to accidents under the influence of initial events (faults, human errors, etc.). At the same time, the parameters representing the concept of safety distance are put forward to effectively control the time. Combined with a certain abroad type of carrier-based aircraft landing process, the landing process safety analysis model is established to verify the applicability of theoretical methods. Through simulation, the hazard modes and their relationship with effective control time are analyzed and the safety constraints model of the landing process is established.

Reliability analysis of arresting hook engaging arresting cable for carrier-based aircraft influenced by multifactors

The carrier-based aircraft landing and arrest process is complex and nonlinear, and includes the coupling effect between the aircraft and arresting system. It has many uncertain factors, which lead to difficulty in the reliability analysis. To make the reliability analysis more accurate and effective, this paper presents some studies. Taking a certain type of carrier-based aircraft as the research object, a dynamic model of the landing and arrest cable was established, and the accuracy of the model was verified using laboratory test results. Based on the model, this paper shows how the key parameters, including the sinking velocity, pitch angle and horizontal velocity, affect the collision rebound performance of the arresting hook. After that, a limit state equation of the arresting hook system’s reliability was established. For the implicit limit state equation, a surrogate model of the reliability of the arresting hook was established using the Support Vector Machine (SVM) method, and then reliability analysis was carried out using the Monte Carlo method. Finally, it was explained in detail how the key parameters affect the reliability of the hook engaging the arresting cable, and some meaningful conclusions were obtained. This analysis method and its results can provide a reference for the top-level parameter design of carrier-based aircraft and reliability research on the arresting systems.

Visual Navigation Method for Carrier-based Aircraft Landing

Carrier landing of fixed-wing aircraft is the most difficult and challenging task in the aerial field. Precise and reliable landing systems are the key to carrier landing. Visual navigation has the advantages of high precision of the relative navigation. Hence, it has become a promising method for landing systems. However, tracking the targets continuously and extracting the coordinates of the targets accurately are challenges for visual navigation due to the complex environment and dramatic distance changes during carrier landing. Therefore, a visual navigation method utilizing an airborne medium-wave infrared camera to track four infrared targets installed on the carrier, which can operate in low visibility weather conditions, is presented in this article. A segmentation detection method was adopted for tracking the targets. The kernel correlation filter was used to detect the targets when the aircraft was far from the carrier stern, which could quickly track targets with relatively constant dimensions. A convolutional neural network classifier based on transfer learning was used to detect the targets when nearing the carrier, thereby reducing the risk of losing targets due to severe dimensional changes. Finally, the relative position and attitude information could be obtained by the POSIT (pose from orthography and scaling with iterations) pose estimation algorithm. On-vehicle experiments were performed, and the results verified the effectiveness of the method.

Research on the Calculation Method of the Success Rate of Carrier-Based Aircraft Landing and Hooking Cable

Research on the Calculation Method of the Success Rate of Carrier-Based Aircraft Landing and Hooking Cable

The Numerical Simulation of UAV's Landing in Ship Airwake

In order to investigate the influence of ship airwake on aerodynamic characteristics of the carrier-based aircraft, UAV's landings in different winds over deck were simulated by Overset Mesh method. Firstly, mesh factors, steady and unsteady methods were compared based on single aircraft carrier. The results showed that the boundary layer mesh around ship didn't show obvious influence for our simulation, and the calculation results between the steady and unsteady time average showed a similar trend. Then, aircraft carrier's flow fields in three wind directions were analyzed, and ship airwake variations with different direction winds over deck were concluded as well. Next, the reliability of Overset Mesh was verified though single UAV's landing simulation. Finally, the coupled flow fields of UAV/ship were studied. The calculation results indicated that aircraft was always in a low dynamic pressure condition, the lift and pitching moment of UAV had apparent changes in landing. Meanwhile, the aerodynamic fluctuations of UAV also revealed differences in different wind directions. The simulation results can be regarded as a reference for the safety assessment of carrier-based aircraft's landing and its control in the future.

Modeling Pilot Behaviors Based on Discrete-Time Series During Carrier-Based Aircraft Landing

A pilot behavior model for carrier landing operations is established based on some realistic mechanisms and strategies. A discrete-time series is applied to model the pilot’s final actions. This pilot model adopts modular design. Furthermore, an information acquirement module, focus mode coordination strategy, and random error probability module are described in detail. Capability indices, including the information acquiring capability, response capability, action accuracy, and distraction capability, are introduced into this model to judge the flight ratings. In addition, this model contains a landing signal officer interface so that the pilot model can respond to the landing signal officer instructions. Finally, a simulation platform is built, on which this pilot model with different operating levels, a test pilot as well as a landing signal officer are emulated. The simulation results indicate that the outputs given by this model agree with the behavioral characteristics of realistic pilots; also, the flight performance can be evaluated by this model.

Modeling Landing Signal Officer Instruction Associated with Operation Guide System

To ensure the operation safety of landing signal officer (LSO) to pilot during carrierbased aircraft landing, the paper proposed a “LSO-pilot-aircraft” instruction associated with operation system. LSO guide mission, and design instruction associated with operation element is been analysed. The relationship and matching of “LSO-pilotaircraft” system are exhibited by instruction associated with the operation model, and “instruction sending-operation responding-deviation correcting” process is realized based on LSO guidance instructions (original version), aircraft real-time flight states (boundary conditions) and pilot response operation (model output). Multiple loading conditions simulation results show that corrective strategies is in line with the actual situation of carrier-based aircraft landing.

Landing Risk Assessment of Carrier-Based Aircraft Based on Fuzzy Multi-Attribute Group Decision Making

In allusion to the special characteristic of longitudinal loop risk assessment in landing process of carrier-based aircraft, this paper extends the concept of decision-maker, and proposes a method of fuzzy multi-attribute decision making with normal fuzzy linguistic variables as decision-making information. Based on the establishment of carrier-based aircraft landing model, the expressions of risk evaluation indicators are ensured, and the relative attribute weight is calculated by the simulation of the safe flight area in landing process. The application of risk assessment is implemented by analogy between standard points and decision-maker. The analysis of numerical examples shows that the method is practical and the application in risk evaluation is reasonable. Multipoint decision information is complete and decision results accord with distributions of touchdown points. Comprehensive evaluation of flight safety with different pilots can be realized.

Study of Disturbances Model on Carrier-Based Aircraft Landing Process

The disturbances in the landing process of carrier-based aircraft include deck movement and ship wake. To guarantee the security of landing process, the simulation and model are necessary for the disturbances, and the deck movement and ship wake should be analyzed as well. On the basis of analysis of disturbances, the disturbances can be catalogued into two types: deck movement and ship wake. Combining with the relevant instructions in the American Army Standard, the mathematical model of each disturbance is established. The simulations of the deck movement and ship wake are also shown in this paper, which can supply the reliable disturbances models for the design of the control system of carrier-aircraft landing process.

Dynamics Model of Carrier-based Aircraft Landing Gears Landed on Dynamic Deck

In order to study the carrier-based aircraft landing laws landed on the carrier, the dynamics model of carrier-based aircraft landing gears landed on dynamic deck is built. In this model, the interactions of the carrier-based aircraft landing attitude and the damping force acting on landing gears are considered, and the influence of dynamic deck is introduced into the model through the deck normal vectors. The wheel-deck coordinate system is put forward to solve the complex simulation problem of force-on-wheel which comes from the dynamic deck. At last, by simulation, it is demonstrated that the model can be applied to landing attitude when the carrier-based aircraft is landing on the dynamic deck, it is also proved that the model is comprehensive and suitable for any abnormal landing situation.

Corrosion of Aircraft Landing Gear Steels

ABSTRACT Carrier-based aircraft landing gear demands a tough, corrosion-resistant material. Because of its high tensile strength, 300M steel was accepted as the standard material for aircraft landing gear. However, its corrosion resistance and fracture toughness are low, and is ill-suited for advanced aircraft landing gear. A newly developed nickel-cobalt alloy steel, named “AerMet 100,” has an outstanding combination of high fracture toughness and high tensile strength. Since its mechanical properties surpass those of the 300M steel, it has great potential for application to aircraft landing gear and other fracture critical components. However, its corrosion behavior was not fully understood. This study was initiated to characterize the corrosion behavior. The characterization effort included clarification of stress corrosion cracking, immersion corrosion, salt spray corrosion, and humidity corrosion of AerMet 100 steel. For comparison, an identical study was concurrently performed for 300M steel. The results indicate that AerMet 100 steel is superior to 300M steel with respect to corrosion resistance as well as mechanical properties.