Research On Compound Self-calibration Method Of Time Grating Angular Displacement Sensor For Complex Electromechanical Systems

At present,in the face of extremely complex conditions such as large,high-speed,heavy-load,strong vibration and strong pollution,and special working environments such as hollow,narrow and weight limited,the frontier equipment manufacturing technology in our country is still constrained by the problem of Closed-loop Detection and control.Although parasitic time grating angular displacement sensor provides us with a way to get rid of the above problems,the system under the above conditions usually can not install external precision angle reference online,which makes it difficult to calibrate the sensor frequently or at low cost.Consequently,how to keep the parasitic time grating angular displacement sensor in high precision for a long time under the above conditions is not only the key problem that the industrialization and popularization of the sensor are restricted,but also one of the key problems that the development of advanced equipment manufacturing technology in China is restricted.To solve those problems,in this paper,by taking the self-calibration method which does not rely on the external precision angle reference as the research object,taking the parasitic time grating angular displacement sensor as the calibration object,and combining theoretical analysis,mathematical modeling and experimental verification,the research on the compound self-calibration method is carried out on the basis of fully investigating the related researches at home and abroad and deeply analyzing the research trend.The main research contents and innovative achievements summarized as follows:The main properties of fixed distance transform are analyzed and summarized.These properties are very important to the theoretical analysis and practical application of the fixed-distance difference function,and it is helpful to analyze the possibility of the fusion of self-calibration method based on fixed-distance transform and other self-calibration methods.Two realization methods for fixed distance transform self-calibration based on single reading head and double reading heads are put forward,and another self-calibration method named coaxial sensors relative rotation is proposed.By establishing mathematical models of those three self-calibration methods,analyzing their calibration errors,and summarizing their boundary conditions,the theoretical basis for fusing different independent self-calibration methods into compound self-calibration methods can be obtained.The re-fusion compound self-calibration method is proposed.The above three independent self-calibration methods are fused into compound self-calibration methods in different ways which make the re-fusion compound self-calibration method come into being finally.And the boundary conditions of each compound method are analyzed separately.The re-fusion compound self-calibration method,which is the fusion of first two compound self-calibration methods,can achieve expected calibration effect just by designing the characteristics of self-calibrated sensor in a given way.The experimental verification and application verification of the above self-calibration methods and their boundary conditions have been completed.The experimental verification platform is designed for the purpose of principle verification and boundary conditions verification.And the feasibility of each self-calibration method and the validity of its boundary conditions have been verified respectively on the experimental platform.What is more,according to the boundary conditions of re-fusion compound self-calibration method,the parasitic time grating angular displacement sensor with matched characteristics is designed and applied to a practical machine tool which is the application verification platform.And the feasibility of the re-fusion compound self-calibration method has been verified once again on the application platform.Experimental results indicate that the peak to peak value of measurement error of the designed sensor decreases from about 590? before self-calibration to about 5? after self-calibration,which means the re-fusion compound self-calibration method has significant practical value.What is more,the re-fusion compound self-calibration method has been applied to some other practical projects,like large precision CNC machining center,and achieved remarkable calibration results.In conclusion,this research provides a practical compound self-calibration method of time grating angular displacement sensor for complex electromechanical systems,which can maintain the sensor's high precision state online without relying on the external precision angle reference.And it also provides a theoretical basis for future research on how to match suitable self-calibration methods for different applications.