Analysis Of Geometric Error Sensitivity And Control System For Semi-flexible Wall Nozzle

The quality of flow field is an important index to measure the performance of wind tunnel test.As the core part of the wind tunnel,the molding quality of nozzle section has a decisive influence on the flow field quality of the wind tunnel.In the process of wind tunnel test,geometric errors,such as machining and manufacturing of parts of parallel mechanism of nozzle segment,have influence on the precision of the molding of nozzle section.So,it is of great significance to study the sensitivity coefficient which is related to the geometric errors of the throat block mechanism and discuss the influence of the input geometric error and output error to improve the quality of the flow field and the accuracy of the test data.This paper takes the parallel mechanism of the nozzle section of a wind tunnel as the research object and study the its kinematics,kinetics,geometric error,sensitivity coefficient of geometric error,geometric error of the input,output error and the PC control program.The main work of this paper includes:(1)Analyze the existing problems of the traditional throat block mechanism and combined with the requirements of synchronous control to analyze the optimal design of the existing laryngeal mechanism and its advantages.Based on the performance of the throat block control system,this paper discusses the optimal design scheme of the throat block mechanism which includes control system structure and the selection of the control system.(2)Analytical and iterative methods are used to analyze the positional solution and inverse solutions of kinematics of the laryngeal mechanism.Study the relationship between the motion of the driving mechanism and the throat block mechanism with the change of time.The Lagrange equation is used to analyze the kinetics of the throat block mechanism.The multi-body kinetics model of the optimal design of the throat block mechanism is established.The validity of the theoretical analysis of kinematics and kinetics is verified by simulation.(3)Based on the the positional solution and inverse solutions of kinematics,this paper proposes an optimization design scheme of the geometric error and sensitivity modeling method of the throat block mechanism,and analyze the influence of the rod length error and hinge clearance error on the global sensitivity coefficient and output error of the mechanism.(4)According to the control performance requirements of the optimal design scheme of the throat block mechanism,the throat block mechanism control system framework and upper computer software function are designed.The motion control error compensation process based on the displacement of the throat block mechanism is proposed,which effectively improves the accuracy of motion control of the throat block mechanism.