Research On Nonlinear Synchronous Control And Active Fault Tolerance Method Of Dual-redundant Aircraft Electro-hydraulic Servo

Modern aircraft is developing rapidly in the direction of high altitude and high speed,and the control of aircraft rudder surface is the key factor to determine the flight attitude of aircraft,and its stability is very important for the safety-oriented aircraft.One of the main measures to improve the stability of the rudder surface is to adopt redundancy technology,that is,to use multiple sets of hydraulic actuators to drive the same rudder surface in parallel.There is a potential problem in this way,which is synchronous output problem.At the same time,in the process working of the redundancy system,there may be varying degrees of failure,which causes great hidden trouble to the flight safety of the aircraft.Therefore,the following aspects are studied in this paper for the double redundancy aircraft electro-hydraulic steering gear system:(1)Aiming at the double redundancy aircraft electro-hydraulic steering gear system,the typical nonlinear existing in the system is analyzed and modeled,and the synchronization problem under different connection conditions is theoretically analyzed.The key hydraulic components of the system are modeled in detail in AMESim,and the key parameters are set and verified.(2)A synchronous control strategy is designed for rigid connection and flexible connection of aircraft electro-hydraulic steering gear system with double redundancy.For the rigid connection,the synchronization problem lies in the synchronization of the output force of the two actuators.Therefore,a force synchronization controller is designed based on the difference of the load pressure difference of the two actuators,and the position control of the actuators is integrated,which can effectively suppress the force disputes caused by the parameter deviation of the two actuators.For the flexible connection,the synchronization problem lies in the synchronization of the output displacement of the two actuators.Therefore,the position tracking error and displacement synchronization error of the two actuators are fused into a unified design of cross-coupling position error.Based on the stability of Lyapunov function,it is proved that the position tracking error and displacement synchronization error can converge to zero.(3)Based on flexible connection,active fault-tolerant control is further studied.The faulttolerant controller adopts three kinds of technical means,which can identify system parameters by means of indirect parameter adaptive and converge to the true value of parameters,which is very important for fault identification.The extended state observer is used to estimate the integrated disturbance in hydraulic system,including parameter estimation error and disturbance caused by faults.Finally,self-adjusting integral robust control is used to suppress and observe residual errors to further improve the controller performance.The organic combination of the three makes the designed active fault-tolerant controller have strong antiinterference performance and active fault-tolerant performance,which can effectively prevent the degradation of system performance and quickly recover part of the control performance.(4)The co-simulation platform is used to compare and verify the designed controller,and the results are analyzed in detail.The effectiveness and superiority of the proposed controller are verified by combining the theory and simulation results.