Study On Test Force Control System Of The Measuring Instrument For Spherical Plain Bearing Clearance

Clearance is one of the important indexes to measure the performance of spherical plain bearing.Compared with ordinary bearings,an accurate detection load is necessary to measure the clearance of spherical plain bearings,which is defined as force test.However,there are few special measuring instruments of spherical plain bearing clearance,in addition,most of these instruments have low control precision of test force and poor dynamic performance.In view of the above situation,to make the test force loading process fast,steady and accurate,this paper used the method of theoretic analysis and experimental verification to improve the performance of test force control system and optimize the corresponding structures based on the second generation measuring instrument of spherical plain bearing clearance which was designed by "self-lubrication bearings common technology lab of Yanshan University.The main research work is as follows:The mathematical model of the test force control system was established.Firstly,the compositions of the special instrument were analyzed briefly to confirm the concept of the test force control system and the relationship among different parts.Secondly,the mathematical models of the servo drive system and the mechanical transmission system were established respectively based on the electrical control principle and mechanical system dynamics.Finally,the PID Modern control technology was used to build the mathematical model of the whole system.The friction model of the test force control system was established and the friction compensation was conducted.Firstly,the test force loading curve was analyzed,the impacts of friction of the mechanical transmission system on the dynamic characteristics and the accuracy of the test force loading process were confirmed.Secondly,according to the variation of the friction,several assumptions were put forward.Based on proper experiments,the parameter identification was conducted,then the friction force model of mechanical transmission system was established.Finally,based on the friction model,the friction compensation was realized by Matlab/Simulink.The dynamic characteristics of the test force control system were analyzed.First,based on the friction model,the Simulink simulation model of the test force control system was established and the optimal adjusting parameters were confirmed.Next,the dynamic characteristics of the test force were analyzed and the influences of mechanical parameters,such as stiffness and damping and inertia on the response of the system were researched deeply.At last,the mechanical structure of the transmission system was optimized.The improved system was debugged to verify the correctness and reliability of the mathematical model and simulation results.