| Aircraft takeoff and landing taxiing is one of the most critical processes in the flight mission,while a well-designed aircraft braking system is the key technology to ensure taxiing safety.Compared with the traditional hydraulic brakes,the all-electric braking system has no risk of hydraulic oil leakage and fire,and has high braking efficiency,fast response speed and high system safety and reliability,representing the most recent development trend of aircraft braking system technology.The aircraft all-electric brake is a complicated and volatile dynamic physical process,whose working process is affected by the safety constraints of slip rate,synchronization constraints of multiple electromechanical actuators and communication constraints caused by the networked structure,thus posing a demanding challenge to the safety and efficiency of the aircraft all-electric brake system.Based on the aircraft all-electric brake system model,the thesis analyzes these three constraint problems from multiple levels and proposes a targeted controller design method under different constraints so as to ensure the safety and efficiency of the aircraft all-electric brake system.Firstly,the aircraft brake dynamics model is established based on the mechanism modeling method,and the stability working conditions of the anti-skid brake system are analyzed based on the frequency domain analysis method.According to the composition structure of the all-electric brake system and its working principle,the control architecture design of an aircraft all-electric brake system is carried out;based on the aircraft brake dynamics model and the electromechanical actuator dynamics model,the all-electric brake system model is established.Based on the aircraft brake dynamics model and the electromechanical actuator dynamics model,the all-electric brake system model is established.With the local linearization method,the open-loop and closed-loop stability conditions of the all-electric brake system are analyzed under two different control modes of deceleration rate and slip rate,and the slip rate safety constraint boundary is obtained,which lays the foundation for the subsequent research.Secondly,at the level of slip rate safety constraint control: to address the possible problems of deep wheel skidding or even locked in the aircraft braking process,a new anti-saturation robust adaptive slip rate constraint control method based on the new sliding mode extreme value runway search and obstacle Lyapunov function is proposed to solve the safety problem of the aircraft all-electric brake system,and also to ensure the adaptive slip rate constraint control to various runway conditions,thus ensuring the braking efficiency and the braking efficiency.thus ensuring the braking efficiency.The comprehensive consideration combines the runway identification method and the slip rate constraint controller to improve the comprehensive braking efficiency of the closed-loop control system under the premise of ensuring the safety constraint of slip rate under various runway conditions.Again,at the level of multi-electromechanical actuator constraint control: for the motion synchronization problem among multiple electromechanical actuators in the aircraft all-electric brake system actuator,the thesis proposes the friction compensation method based on adaptive neural network and the static and dynamic synchronization compensation method of brake pressure from two perspectives of single-axis decoupling and multi-axis synchronization,respectively.Single-axis decoupling focuses on solving the nonlinearity and uncertainty of individual electromechanical actuators,and designs a brake pressure controller based on adaptive friction compensation to ensure the synchronization accuracy of the overall brake pressure by improving its servo control accuracy.The multi-axis decoupling reduces the steady-state and dynamic errors of the brake pressure of the brake actuator by considering the static pressure and dynamic pressure differences between multiple electromechanical actuators and investigating various static synchronization strategies and dynamic compensation strategies.In addition,at the constrained control level of the whole aircraft brake system: a complementary sliding mode controller based on the switching threshold event trigger mechanism is proposed for a series of network constraint problems in the networked control process of the all-electric brake system.For the perturbations and uncertainties existing in the feedback channel of the system,an extended state observer based on event triggering is proposed to solve the problems of state observation and perturbation identification in the system at the same time.For the network bandwidth constraint problem in the forward channel of the system,the event-triggered complementary sliding-mode output feedback controller is proposed to reduce the system tracking error and improve the control performance.Based on the fixed threshold trigger mechanism and relative threshold trigger mechanism,a switching threshold trigger mechanism strategy is proposed to further optimize the network control efficiency of the all-electric brake system.Finally,to verify the effectiveness of the proposed control method,the controller-in-the-loop simulation tests are conducted based on the real-time simulation computer and the developed anti-skid brake controller.The experimental results show that the designed constraint control method can improve the integrated control performance based on the constraint performance and braking efficiency under the premise of considering the various constraints existing in the all-electric brake system. |
