Research On Thrust Vector Measurement For Circumferential Power System

To achieve accurate control of the aircraft at high altitude and low pressure,the traditional attitude control system of aircraft changes rudder surface control system to circumferential power system,that is,the attitude control is realized through co-ignition of multiple attitude control engine.Thrust vector,as a key performance parameter of lateral force control technology,is of great significance for ensuring control precision and improving target hit rate.Therefore,accurate measurement of lateral thrust is particularly significant.In this paper,thrust vector measurement of circumferential power system is taken as the research object,and a piezoelectric six-dimensional force test system is developed.The simulation analysis,calibration test and simulated loading experiment proves that the designed test system has the advantages of high rigidity,high natural frequency,high testing precision and well stability,which ensures the stability and reliability of test results.The piezoelectric effect expression is obtained by studying properties of quartz crystal,piezoelectric mechanism and piezoelectric effect.The design of three-dimensional force sensor is completed by studying the selection of crystal cutting,the selection and composition of the crystal group.Based on the four-point supported piezoelectric dynamometer,the preliminary design of test system is completed with the structural characteristics of circumferential power system.Furthermore,the theoretical principles of measurement are introduced,including the definition of thrust vector parameters and the theoretical model of test system.According to the bearing performance requirements and dynamic performance requirements of test system,the static and modal analysis of test system model is carried out by Workbench.The result shows that the stiffness and natural frequency of test system can meet the measurement requirements,and the feasibility of spatial thrust vector measurement is verified by simulation analysis.Three-axis force and three-axis moment calibration experiments are conducted on the test system.By analysing the calibration data and decoupling compensation,the nonlinear error and repeatability error of the test system are all within 2%,and the interphase interference is not more than 3%,which meets the static test requirements of lateral force.The dynamic performance of the test system is verified by hammering.The results show that the test system has good dynamic performance and meets the dynamic test requirements of thrust vector.The accuracy,stability and reliability of measurement results are further verified by the orthogonal simulation loading test and the four-station simulation loading test.The uncertainty of the test system is within 3% through the uncertainty analysis,which meets test technology requirements.