Aircraft Anti-skid Braking System Research Articles

A novel aircraft anti-skid brake control method based on multi-objective model predictive control for suppressing landing gear walk vibration

To suppress the longitudinal landing gear vibration (gear walk) induced by the aircraft anti-skid braking system (ABS), an aircraft ABS control method based on multi-objective model predictive control (MPC) is proposed. The landing gear is simplified to be a cantilever beam with tip mass to analyze the vibration mechanism, based on which a low-order model to describe both the braking dynamics and the gear walk dynamics is derived. The multi-objective ABS controller is then designed to achieve landing gear walk suppression as well as to ensure the braking efficiency, simultaneously. Considering that the aircraft ABS is a strongly nonlinear system with demanding real-time requirements, the successive linearization based MPC (SLMPC) method is employed to reduce the computational burden. To comply with the SLMPC design, a tire-road friction parameter identification method by combining the extended Kalman filter (EKF) and linearized recursive least squares (LRLS) is also proposed. Finally, the effectiveness of the proposed control method is verified through both simulation and experimental studies, which demonstrate the good performance of the proposed method.

Application of Deep Reinforcement Learning in Reconfiguration Control of Aircraft Anti-Skid Braking System

The aircraft anti-skid braking system (AABS) plays an important role in aircraft taking off, taxiing, and safe landing. In addition to the disturbances from the complex runway environment, potential component faults, such as actuators faults, can also reduce the safety and reliability of AABS. To meet the increasing performance requirements of AABS under fault and disturbance conditions, a novel reconfiguration controller based on linear active disturbance rejection control combined with deep reinforcement learning was proposed in this paper. The proposed controller treated component faults, external perturbations, and measurement noise as the total disturbances. The twin delayed deep deterministic policy gradient algorithm (TD3) was introduced to realize the parameter self-adjustments of both the extended state observer and the state error feedback law. The action space, state space, reward function, and network structure for the algorithm training were properly designed, so that the total disturbances could be estimated and compensated for more accurately. The simulation results validated the environmental adaptability and robustness of the proposed reconfiguration controller.

Design of an NSMCR Based Controller for All-Electric Aircraft Anti-Skid Braking System

In this paper, a relative threshold event-triggered based novel complementary sliding mode control (NSMCR) algorithm of all-electric aircraft (AEA) anti-skid braking system (ABS) is proposed to guarantee the braking stability and tracking precision of reference wheel slip control. First, a model of the braking system is established in strict-feedback form. Then a virtual controller with a nonlinear control algorithm is proposed to address the problem of constraint control regarding wheel slip rate with asymptotical stability. Next, a novel approaching law-based complementary sliding mode controller is developed to keep track of braking pressure. Moreover, the robust adaptive law is designed to estimate the uncertainties of the braking systems online to alleviate the chattering problem of the braking pressure controller. Additionally, to reduce the network communication and actuator wear of AEA-ABS, a relative threshold event trigger mechanism is proposed to transmit the output of NSMC in demand. The simulation results under various algorithms regarding three types of runway indicate that the proposed algorithms can improve the performance of braking control. In addition, the hardware-in-the-loop (HIL) experimental results prove that the proposed methods are practical for real-time applications.

PSO Optimized Active Disturbance Rejection Control for Aircraft Anti-Skid Braking System

A high-quality and secure touchdown run for an aircraft is essential for economic, operational, and strategic reasons. The shortest viable touchdown run without any skidding requires variable braking pressure to manage the friction between the road surface and braking tire at all times. Therefore, the manipulation and regulation of the anti-skid braking system (ABS) should be able to handle steady nonlinearity and undetectable disturbances and to regulate the wheel slip ratio to make sure that the braking system operates securely. This work proposes an active disturbance rejection control technique for the anti-skid braking system. The control law ensures action that is bounded and manageable, and the manipulating algorithm can ensure that the closed-loop machine works around the height factor of the secure area of the friction curve, thereby improving overall braking performance and safety. The stability of the proposed algorithm is proven primarily by means of Lyapunov-based strategies, and its effectiveness is assessed by means of simulations on a semi-physical aircraft brake simulation platform.

Robust Self-Learning PID Control of an Aircraft Anti-Skid Braking System

In order to deal with strong nonlinearity and external interference in the braking process, this paper proposes a robust self-learning PID algorithm based on particle swarm optimization, which does not depend on a precise mathematical model of the controlled object. The self-learning function is used to adapt to the diversity of the runway road surface friction, the particle swarm algorithm is used to optimize the rate of self-learning, and robust control is used to deal with the modeling uncertainty and external disturbance of the system. The convergence of the control strategy is proved by theoretical analysis and simulation experiments. The superiority and accuracy of the method are verified by NASA ground test results. The simulation results shows that the adverse effect of the external disturbance is suppressed, and the ideal trajectory is tracked.

Multiphase-Based Optimal Slip Ratio Tracking Control of Aircraft Antiskid Braking System via Second-Order Sliding-Mode Approach

This article addresses a novel multiphase-based real-time optimal slip ratio tracking control problem of an aircraft antiskid braking system (ABS) based on the second-order sliding-mode approach. First, a comprehensive dynamic model of an aircraft ABS is established, in which the coupling mechanism of the longitudinal, the vertical, and the pitching dynamics of the aircraft are thoroughly considered. Second, for the aircraft ABS with high nonlinearity, since the measurements of aircraft velocity and acceleration cannot be transmitted to the aircraft ABS in time, the second-order sliding-mode differentiator (SMD) will be designed to estimate them simultaneously. Then, the optimal slip ratio signal, which formulates the maximum friction coefficient, will be updated based on the static friction coefficient model with real-time measured and estimated signals. Furthermore, a novel multiphase-based slip ratio regulation algorithm integrated with the second-order sliding-mode control strategy is proposed on the basis of runway characteristics to track the optimal slip ratio signal, which can not only stop the aircraft faster but prevent the mainwheel from final locking. Finally, the simulation results are presented to demonstrate that the aircraft antiskid braking algorithm proposed in this article can effectively prevent the mainwheel from locking under different runway conditions, and significantly improve the braking efficiency.

Adaptive Fuzzy Active-Disturbance Rejection Control-Based Reconfiguration Controller Design for Aircraft Anti-Skid Braking System

The aircraft anti-skid braking system (AABS) is an essential aero electromechanical system to ensure safe take-off, landing, and taxiing of aircraft. In addition to the strong nonlinearity, strong coupling, and time-varying parameters in aircraft dynamics, the faults of actuators, sensors, and other components can also seriously affect the safety and reliability of AABS. In this paper, a reconfiguration controller-based adaptive fuzzy active-disturbance rejection control (AFADRC) is proposed for AABS to meet increased performance demands in fault-perturbed conditions as well as those concerning reliability and safety requirements. The developed controller takes component faults, external disturbance, and measurement noise as the total perturbations, which are estimated by an adaptive extended state observer (AESO). The nonlinear state error feedback (NLSEF) combined with fuzzy logic can compensate for the adverse effects and ensure that the faulty AABS maintains acceptable performance. Numerical simulations are carried out in different runway environments. The results validate the robustness and reconfiguration control capability of the proposed method, which improves AABS safety as well as braking efficiency.

High-efficiency aircraft antiskid brake control algorithm via runway condition identification based on an on-off valve array

The aircraft antiskid braking system is an important hydraulic system for preventing tire bursts and ensuring safe take-off and landing. The brake system adjusts the force applied on the brake discs by controlling the brake pressure. Traditional aircraft antiskid braking systems achieve antiskid performance by controlling the braking pressure with an electrohydraulic servo valve. Because the pilot stage of an electrohydraulic servo valve is easily blocked by carbonized hydraulic oil, the servo valve would become a dangerous weak point for aircraft safety. This paper proposes a new approach that uses an on-off valve array to replace the servo valve for pressure control. Based on this new pressure control component, an efficient antiskid control algorithm that can utilize this discontinuous feature is proposed. Furthermore, the algorithm has the ability to identify the runway circumstances. To overcome the discontinuity in the process of using an on-off valve array, the Filippov framework is introduced. The conditions of convergence of the system are also discussed. The results of the digital simulations and the hardware-in-the-loop (HIL) braking experiments are used to verify the efficiency and stability of the proposed control algorithm. The method also proves that the on-off valve array can replace the servo valve perfectly as a new type of antiskid braking pressure control component.

Mixed Slip-Deceleration PID Control of Aircraft Wheel Braking System

Aircraft antiskid braking system is designed to prevent the main wheels from locking and additionally seeking the optimal braking performance. Wheel deceleration is the traditional controlled target used in antiskid system, since it can be easily measured by angular velocity transducer. However the optimal target value is hard to find due to the changing of road-surface and aircraft velocity. An alternative controlled target is the wheel longitudinal slip which is more robustly controllable under all conditions. But the wheel slip cannot be measured directly, that will definitely result in control error from the poor estimated aircraft speed. In this work a PID control scheme based on mixed slip-deceleration input variable is proposed for aircraft antiskid braking system. This control algorithm is able to stabilize the wheel slip around any equilibrium point. Moreover, it inherits all the appealing characteristics of slip control, while overcoming its sensitivity to slip measurement errors.

Aircraft Antiskid Braking Control Method Based on Tire–Runway Friction Model

An aircraft antiskid braking system control method based on tire–runway friction model is proposed in this paper. The purpose is to keep tire–runway friction around its maximum value and prevent wheels from working in low-braking-efficiency regions. This paper defines a slip-factor parameter to distinguish between the adhesion region and the slip region, so that we can accurately obtain the location of the tire–runway friction peak. The slip factor needs signals, including wheel angular velocity and braking torque, and needs no aircraft longitudinal velocity value, which is difficult to detect. The proposed control method can automatically identify current runway conditions and yields robust performance with respect to unknown or changing runway conditions. Computer software simulations are conducted to verify the feasibility of the control method, and experiments are conducted on a ground-inertia braking test bench to validate the control method. The results show that the controller can detect the actual maximum tire–runway friction peak and also provide high adaptability in different tire–runway conditions.

Antiskid Braking Control with On/Off Valves for Aircraft Applications

Traditional pressure servo valves used in hydraulic aircraft antiskid braking system are sensitive to contamination and require a high maintenance cost. This paper proposes an on/off-valve-based antiskid braking system with simple structure and high resistance to contamination for aircraft applications. It can improve the system reliability and reduce maintenance cost. An aircraft longitudinal motion model and a hydraulic antiskid braking system model with on/off valves are formulated. Based on these models, a switched controller with delay compensation is developed for an aircraft antiskid braking system using on/off valves. It features a switching surface derived through backstepping to govern the switching action of the valves and a pressure predictor to compensate the delay caused by response time of valves and brake lines. In addition, an approximation brake line model and a tire friction force observer are included in the controller to estimate the brake pressure and friction force, respectively. The system stability is analyzed with Lyapunov theory and Filippov framework. At last, hardware-in-loop tests are conducted on a research prototype of the hydraulic brake system and a computer-based simulator embedded with aircraft motion models. Experimental results show that the proposed on/off-valve-based aircraft antiskid braking system presents a smooth braking performance, and it is robust to uncertain road conditions.

Adaptive Control for Aircraft Anti-Skid Braking System

The aircraft tire friction force varies significantly with different types of runway materials, surface lubricity and vertical load, which affects the braking efficiency. In this paper, the dynamic LuGre model is introduced to describe the friction force, which could give a projective mapping from the physical unknown runway state to mathematical friction force model with parametric uncertainties. The state observers are employed to estimate the unmeasurable internal friction states of the friction force model and the estimates are substituted into the parameter adaptive law to obtain the current runway state. The pseudo-static friction force model is calculated online to obtain the maximum friction coefficient and its slip ratio. This slip ratio is set as the tracking target for the well-designed feed-forward controller based on the feedback linearization method. The simulation results are shown to verify the proposed method.

Slid Mode VSC for Aircraft Anti-Skid Braking System with Index Reaching Law

Aircraft anti-skid braking system providing protection for the safety of the aircraft landed by controlling the brake pressure to be maintained slip ratio in best condition. The aircraft anti-skid braking system is hard to control as the nonlinear model of the aircraft dynamics, the uncertainty of friction between the tires and the ground of braking process. With the study of slip ratio and research of aircraft anti-skid braking system dynamics model, the sliding mode variable structure controller is designed. Then index reaching law is adopted to eliminate the system chattering and the performance is analyzed, further more the robustness is strengthen. Simulation results indicate that: the slip ratio follows the optimum slip ratio, the input signal is smooth, achieve the purpose.

Research on Simulation of Aircraft Electro-Hydrostatic Actuator (EHA) Anti-Skid Braking System

With the background of the development of Aircraft Anti-skid Braking System, a new aircraft Electro-Hydrostatic Actuator (EHA) of a certain model fighter is designed to meet the need of the braking system. The paper describes the principle of work and features of the EHA, and gives the specific requirements of the system. The selection and performance of the motor, pump and hydraulic cylinder are optimized. Then, the paper describes the principle of work and features of the EHA, models and simulates it with MATLAB/Simulink., and analyzes the effects of all structural parameters on the performance. The results of EHA reach the design target of dynamic performance. Finally, the whole model of the aircraft system is built and established based on the EHA model and results. The results of the dry runway condition verify the correctness of the EHA design, so the Hydro Actuator of traditional aircraft anti-skid braking system could be replaced by EHA.