Research On Absolute Linear Inductive Displacement Sensor With Complementary Coupling Structure

Currently linear displacement sensor acts a significant role in the intellectualized manufacture equipment.Due to linear displacement sensor having direct impacts on the machining accuracy of numerical control machine tool,it needs to achieve a higher accuracy and stability.And inductive displacement sensor compared with grating has lower cost and the better resistance to poor working condition.Besides the above sensor because of its excellent stability,better anti-interference ability and reliability is widely applied in the existing numerical control machine tool.As an inductive displacement sensor,the inductive displacement time grating has the function of measuring angular and linear displacement.In the aspect of measuring angular displacement,time grating achieves excellent stability and reliability.While time grating has performed insufficient stability,lower accuracy and anti-interference ability in the aspect of measuring angular displacement,because of structure defects.What's worse,structure defects of time grating can cause obstacles in measuring absolute linear displacement and serious impact on large scale application of time grating.To solve above issue,this research makes further improvement and optimization in the structure of existing inductive displacement time grating.In this research,a series of improvements are as follows.Firstly,a complementary coupling structure to replacing the existing unilateral winding structure is proposed.Secondly,for adapting to some special installation excitation,the magnetizer is used to be the base metal of probe to change reluctance of sensor,and excitation coil and induction coil are integrated into a same PCB,which makes all leads placed in one edge of PCB and makes the probe without leads.Besides,improving the layout of excitation coil and induction coil effectively decreases the measurement error of sensor.Meanwhile,to realize absolute linear displacement measurement,using two measuring units which is independent of each other and digital coding are put into practice in this research.The main research contents and results are as follows:(1)According existing structure of unilateral winding linear displacement sensor,a complementary coupling sensor structure is proposed,which significantly enhances the voltage of sensor output signal and improves signal distortion that is caused by the installation error and the manufacturing error.(2)In this research the digital model of this new structure sensor is established and simulated.In more detail,using 3D software establishes the digital model,and using electromagnetic simulation software builds 3D transient magnetic field simulation analysis of the digital model.What's more,this new structure sensor is proven to be effective in decreasing signal distortion by the result of simulation.(3)Measurement and control test bench and electrical measurement and control system are established in this research.In detail,the experimental study includes the design of experiment platform,the test on the prototype of the new structural sensor,as well as troubleshooting and error analysis for each measurement module of the electrical measurement and control system.(4)In this research using two measuring units which is independent of each other realize the digital coding over the entire length of the measurement to achieve absolute linear displacement.(5)In this research,the mathematical model of measurement errors from this new structure sensor are established.By experiment study,measurement errors are analyzed and the solution to decreasing measurement errors are studied.From the result of the experiment study,it is shown that this new structure sensor has enough stability and good anti-interference ability,and compared with unilateral winding linear displacement sensor the 50% higher measuring accuracy of sensor has been realized.In conclusion,for the research on theoretical derivation,simulation analysis,experiment study,and etc,the better stability and good anti-interference ability of this new structure sensor is verified.