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This paper designs a practical automatic carrier landing system (ACLS) that utilizes direct lift control (DLC) technology, and the controller parameters are optimized by using the enhanced fruit fly optimization algorithm with escape predation mechanism (EPFOA). The designed ACLS comprises the control channels of elevator, flap and throttle. The coordinated action of the elevator and flap can generate direct lift, enabling the aircraft to approach the desired glide path quickly and accurately. A decoupling module is designed to enhance the attitude stability of the aircraft during landing, thereby increase the success rate of landing. In order to achieve the better control effectiveness, the EPFOA is proposed to optimize the controller parameters of the DLC-based ACLS. Inspired by the predator-escape behavior between dingoes and sheep, EPFOA divides the whole fruit fly swarm into three categories: discovered escaping fruit fly (DEF), escaping fruit fly (EF) and predator fruit fly (PF). The PFs can ensure the population of convergence, while the DEFs and EFs can preserve the diversity of the population and avoid falling into local optima. Experiments are conducted in various cases, and the designed DLC-ACLS demonstrates superior ability in flight path adjustment and attitude control compared to the traditional F/A-18 ACLS in landing control. Additionally, the proposed EPFOA shows superior performance compared to other optimization algorithms. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this paper is to solve the challenging problem of automatic carrier landing with the presence of environmental disturbances. Therefore, a global fast terminal sliding mode control (GFTSMC) method is proposed for automatic carrier landing system (ACLS) to achieve safe carrier landing control. Design/methodology/approach: First, the framework of ACLS is established, which includes flight glide path model, guidance model, approach power compensation system and flight controller model. Subsequently, the carrier deck motion model and carrier air-wake model are presented to simulate the environmental disturbances. Then, the detailed design steps of GFTSMC are provided. The stability analysis of the controller is proved by Lyapunov theorems and LaSalle's invariance principle. Furthermore, the arrival time analysis is carried out, which proves the controller has fixed time convergence ability. Findings: The numerical simulations are conducted. The simulation results reveal that the proposed method can guarantee a finite convergence time and safe carrier landing under various conditions. And the superiority of the proposed method is further demonstrated by comparative simulations and Monte Carlo tests. Originality/value: The GFTSMC method proposed in this paper can achieve precise and safe carrier landing with environmental disturbances, which has important referential significance to the improvement of ACLS controller designs. [ABSTRACT FROM AUTHOR]

Purpose: This paper aims to propose a novel control scheme and offer a control parameter optimizer to achieve better automatic carrier landing. Carrier landing is a challenging work because of the severe sea conditions, high demand for accuracy and non-linearity and maneuvering coupling of the aircraft. Consequently, the automatic carrier landing system raises the need for a control scheme that combines high robustness, rapidity and accuracy. In addition, to exploit the capability of the proposed control scheme and alleviate the difficulty of manual parameter tuning, a control parameter optimizer is constructed. Design/methodology/approach: A novel reference model is constructed by considering the desired state and the actual state as constrained generalized relative motion, which works as a virtual terminal spring-damper system. An improved particle swarm optimization algorithm with dynamic boundary adjustment and Pareto set analysis is introduced to optimize the control parameters. Findings: The control parameter optimizer makes it efficient and effective to obtain well-tuned control parameters. Furthermore, the proposed control scheme with the optimized parameters can achieve safe carrier landings under various severe sea conditions. Originality/value: The proposed control scheme shows stronger robustness, accuracy and rapidity than sliding-mode control and Proportion-integration-differentiation (PID). Also, the small number and efficiency of control parameters make this paper realize the first simultaneous optimization of all control parameters in the field of flight control. [ABSTRACT FROM AUTHOR]

This paper addresses the automatic carrier landing problem in the presence of deck motion, carrier airwake disturbance, wind shears, wind gusts, and atmospheric turbulences. By transforming the 6-DOF aircraft model into an affine dynamic with angle of attack controlled by thrust, the equations associated to the resultant disturbances are deduced; then, a deck motion prediction block (based on a recursive-least squares algorithm) and a tracking differentiator-based deck motion compensation block are designed. After obtaining the aircraft reference trajectory, the backstepping control method is employed to design a novel automatic carrier landing system with three functional parts: a guidance control system, an attitude control system, and an approach power compensation system. The design of the attitude subsystem involves the flight path control, the control of the attitude angles, and the control of the angular rates. To obtain convergence performance for the closed-loop system, the backstepping technique is combined with sliding mode-based command differentiators for the computation of the virtual commands and extended state observers for the estimation of the disturbances. The global stability of the closed-loop architecture is analyzed by using the Lyapunov theory. Finally, simulation results verify the effectiveness of the proposed carrier landing system, the aircraft reference trajectory being accurately tracked. [ABSTRACT FROM AUTHOR]

This paper proposes an innovative automatic carrier landing control law for carrier-based aircraft considering complex ship motion and wind environment. Specifically, a strategy is proposed to synthesize preview control with an adaptive nonlinear control scheme. Firstly, incremental nonlinear backstepping control law is adopted in the attitude control loop to enhance the anti-disturbance capability of the aircraft. Secondly, to enhance the glide slope tracking performance under severe sea conditions, the carrier motion is predicted, and the forecasted motion is adopted in an optimal preview control guidance law to compensate influences induced by carrier motion. However, synthesizing the inner-loop and outer-loop control is not that straightforward since the preview control is naturally an optimal control law which requires a state-space model. Therefore, low-order equivalent fitting of the attitude-to-altitude high-order system model needs to be performed; furthermore, a state observer needs to be designed for the low-order equivalent system to supply required states to the landing controller. Finally, to validate the proposed methodology, an unmanned tailless aircraft model is used to perform the automatic landing tasks under variant sea conditions. Results show that the automatic carrier landing system can lead to satisfactory landing precision and success rate even under severe sea conditions.

This paper addresses the automatic carrier landing problem in the presence of deck motion, carrier airwake disturbance, wind shears, wind gusts, and atmospheric turbulences. By transforming the 6-DOF aircraft model into an affine dynamic with angle of attack controlled by thrust, the equations associated to the resultant disturbances are deduced; then, a deck motion prediction block (based on a recursive-least squares algorithm) and a tracking differentiator-based deck motion compensation block are designed. After obtaining the aircraft reference trajectory, the backstepping control method is employed to design a novel automatic carrier landing system with three functional parts: a guidance control system, an attitude control system, and an approach power compensation system. The design of the attitude subsystem involves the flight path control, the control of the attitude angles, and the control of the angular rates. To obtain convergence performance for the closed-loop system, the backstepping technique is combined with sliding mode-based command differentiators for the computation of the virtual commands and extended state observers for the estimation of the disturbances. The global stability of the closed-loop architecture is analyzed by using the Lyapunov theory. Finally, simulation results verify the effectiveness of the proposed carrier landing system, the aircraft reference trajectory being accurately tracked.

This paper presents a fault-tolerant control scheme, combining nonsingular terminal sliding mode and active disturbance rejection control (NTSM-ADRC) to address actuator failure and external disturbances during the automatic carrier landing process of a carrier-based aircraft using direct lift control (DLC). First, the carrier-based aircraft model, the carrier air-wake model, and the actuator fault model were established. Second, the NTSM-ADRC controller is designed, The unmodeled dynamics of the system, the air-wake disturbance, and the fault term are treated as total disturbances and estimated accurately by extended state observer (ESO). To improve the response characteristics of the controller, the nonlinear error feedback control law is designed by combining the NTSMC. The Lyapunov function is constructed to prove the stability of the closed-loop system. The controller is applied to the aircraft DLC channel, attitude auxiliary channel, and approach power compensation system. The DLC improves the performance of fixed-wing aircraft by directly generating high lift through the flaps to change the aircraft trajectory. Finally, the method is tested by introducing various types of actuator failures. Simulation results demonstrate that the designed longitudinal fault-tolerant carrier landing system exhibits strong robustness and fault tolerance, thereby improving the accuracy of aircraft landing trajectory tracking. [ABSTRACT FROM AUTHOR]

In this paper, a design scheme of automatic carrier landing system (ACLS) control law based on compensating states and dynamic inversion is proposed, in order to eliminate landing risk and air wake disturbance and improve flight quality during landing. First of all, the mathematical model for an aircraft during carrier landing is established and transformed into a low-order linear perturbed model with the involved state variables, which denotes the reference model. Second, a high-dimension field of the landing risk is addressed, which reflects the current and the potential risk degrees due to the subjective prediction of the pilots. The coefficients of the landing risk field are established based on a pilot behavioral model. Third, a concept of compensating states is proposed by this paper. On one hand, the compensating states of the air wake disturbance are estimated from the nonlinear and reference models. On the other hand, the compensating states of the landing risk are composed of the high-dimension risk field. Fourth, automatic carrier landing control law is built with the compensating states of air wake and landing risk, nonlinear dynamic inversion, and feedback signals of the flight states. In the rolling optimization progress, the landing risk, air wake, and nonlinear factors of flight states are dynamically introduced to control the state deviations and suppress landing risk. Test results based on a semi-physical simulation platform indicate that the proposed algorithm brings about an excellent landing performance and an ability to eliminate landing risk and air wake.

This paper studies an automatic carrier landing control problem of fixed-wing aircraft with system uncertainties under the airwake and deck motion disturbances. A robust preview control scheme and an autoregressive (AR) model prediction scheme are originally applied to the automatic carrier landing system (ACLS). The AR model is used to predict the deck motion, which corrects the reference glide slope for relative motion compensation. A novel robust preview control scheme based on the linear matrix inequality (LMI) is proposed for the uncertain nonlinear systems with external disturbances, to make the aircraft track the corrected reference glide slope and reject the airwake disturbance. Simulation results exhibit the better carrier landing performance of the robust preview control scheme than the PID control and robust control schemes.

It is difficult for the intelligent teaching system in colleges to effectively predict student grade, which makes it difficult to formulate follow-up teaching strategies. In order to improve the effect of student grade prediction, this study improves the neural network algorithm, combines support vector machines to build a student grade prediction model, and uses PCA to reduce the dimensionality of the sample data. The specific operation is realized by SPSS software. Moreover, this study removes redundant information inside the input vector and compresses multiple features into a few typical features as much as possible. In addition, the research set a control experiment to analyze the performance of the research model and compare the advantages and disadvantages of the classification prediction effect of traditional machine learning algorithms and neural network algorithms. Through experimental comparison, we can see that the model constructed in this paper has certain advantages in all aspects of parameter performance, and the prediction model proposed in this study has certain effects. [ABSTRACT FROM AUTHOR]

This paper studies a multivariable model reference adaptive control (MRAC) scheme for the automatic carrier-landing control problem of unmanned aerial vehicles (UAVs) with system dynamics of nonlinearity, multivariable coupling and parametric uncertainty. A complete automatic carrier landing system (ACLS) for carrier-based UAVs is developed, which consists of a guidance subsystem and a flight control subsystem. The MRAC scheme is based on a state feedback for output tracking framework with relaxed design conditions, which guarantees the reference glide slope tracking. Simulation results of a nonlinear UAV model demonstrate that the multivariable MRAC based ACLS has a better carrier-landing performance than a fixed control based ACLS. [ABSTRACT FROM AUTHOR]

The robustness of automatic carrier landing system(ACLS) is strong because the of the nonlinearity and uncertainty of carrier-based aircraft model in the final-approach. In order to solve the problem, an adaptive sliding mode control based on dynamic recurrent fuzzy neural network is designed to apply in the longitudinal landing system. Firstly, the adaptive sliding mode control method is used to suppress the disturbance of carrier air-wake. Next, the dynamic recurrent fuzzy neural network is applied to compensate the system failure, which further ensures the accurate tracking of ideal glide slop for the carrier-based aircraft. Finally, the effectiveness of the proposed control algorithm is verified by simulation results. Compared with the normal control system of the ACLS, this design can obviously improve the stability of the system and has a good restraint effect on the disturbance of the carrier air-wake. [ABSTRACT FROM AUTHOR]

Guidance and control is the key technique of the automatic carrier landing of the carrier based aircraft. This paper summarizes the research development of this technique. The approaching routes and several carrier landing modes are given. The principles and key techniques of the radar based guidance system and the satellite based guidance system are respectively described. Several carrier landing control techniques are mainly analyzed, including the control law design, direct lift control, thrust vectoring control, carrier deck prediction and compensation, automatic power compensation and carrier landing safe control. Finally, the future prospects of the guidance and control technique are summarized from the aspects of multi-system integrated carrier landing control and multi-mode fusion carrier landing techniques. [ABSTRACT FROM AUTHOR]

This work addresses the optimal control of carrier landing affected by deck motion and airwake disturbances. Starting from aircraft dynamics written under an affine form, a novel inverse optimal control approach is designed and then used as the main control technique to provide fast and accurate tracking of the aircraft reference trajectory, as well as to improve the convergence performances and the success rate of the automatic carrier landing. A robust automatic control landing system is proposed by designing a novel inverse optimal control algorithm based on disturbance observers (for the estimation and compensation of airwake), a deck motion compensation block, and fixed-time command filters for computing the reference signals and reducing the tracking errors. The proposed optimal scheme includes a guidance controller, an attitude controller (involving the control of the heading angle, attitude angles, and angular rates), and an approach power compensation system. The proposed architecture is proved to be globally stable by using the Lyapunov theory. Finally, the comparative simulation results prove both the reliability of the control scheme and the superiority of the novel inverse optimal control technique over other nonlinear control approaches employed in the design of automatic control landing systems. [ABSTRACT FROM AUTHOR]

In this paper, a novel control parameter design method is presented for the automatic carrier landing system. To overcome difficulties in the manual parameter adjustment task, the pigeon-inspired optimization algorithm is utilized by converting the parameter design problem to an optimization problem. The modified version is proposed to avoid the lack of the diversity of pigeon population in the basic version. Parameters in the inner loop are optimized by computing the fitting difference between an ideal frequency response curve and the frequency response curve of the optimized control system. To optimize control parameters in the H-dot autopilot and the approach power compensation system, a weighted linear cost function in the time domain is adopted. Series of experiments are conducted to demonstrate the feasibility and effectiveness of our method. Comparative results indicate that out method is much better than other methods. [ABSTRACT FROM AUTHOR]

Longitudinal deck motion causes the variation of the height of ideal touch down point, which is a main factor affecting the safety of carrier landing. In order to decrease the influences of longitudinal deck motion on carrier landing, a method of deck motion prediction and compensation is proposed. Deck motion compensator based on lead network and deck motion predictor based on particle filter are designed. The deck motion signal is first processed by the predictor and compensator and then connected to the longitudinal automatic carrier landing system, which helps the carrier aircraft track the deck motion accurately in the final stage of landing and decreases the influences of deck motion on carrier landing. The designed compensator and predictor are examined and compared with other method through simulation experiments in different sea states. Simulation results show that the designed deck motion predictor and compensator can effectively compensate for the landing error caused by deck motion and can significantly improve the safety and accuracy of carrier landing. [ABSTRACT FROM AUTHOR]

An adaptive fault-tolerant control (AFTC) 1 method is developed for an automatic carrier landing system (ACLS) 2 with actuator failures. First, an actuator fault model is added to the linear unmanned aerial vehicle (UAV) 3 model. Then, an AFTC algorithm based on the output feedback designs for output tracking is raised to solve the theoretical problem extracted through the practical automatic carrier landing process. The σ -modification based robust adaptive update law is used for both parameterized and unparameterized fault. Then the stability of the system is verified by Lyapunov function method. Finally, the ACLS simulation is conducted, which includes the guidance law designed by PID method, the flight controller designed by the proposed AFTC method and a deck motion prediction and compensation based on auto-regression (AR) 4 model. The comparison result shows that the improved robust AFTC can effectively deal with both parameterized and unparameterized fault, as well as external disturbances. [ABSTRACT FROM AUTHOR]

The automatic carrier landing system (ACLS) is an indispensable component of modern aircraft carriers, and it can be considered a special cyber-physical system. However, the disturbance of the carrier air-wake in the final approach is detrimental to the landing safety and complicates the design of the ACLS. An air-wake rejection control strategy can be designed by analyzing the signal flow chart. To suppress the air-wake disturbance, the ACLS in this study is designed based on an adaptive backstepping sliding mode control. This design compensates and restrains the flight performance deviation, and it can also ensure the robustness of the system. Compared with the conventional ACLS design, the capability to restrain the flight performance deviation is significantly enhanced. The simulation results show that the system robustness is improved significantly. Moreover, the proposed design can achieve strict control of the ideal glide slope tracking and realize safe landing under the air conditions of the final approach. [ABSTRACT FROM AUTHOR]