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Studies On Key Problems In Dynamic Correction And Improvement Of Dynamic Correction Methods For Strain Multi-axis Force Sensor

Posted on:2020-10-15Degree:MasterType:Thesis
Country:ChinaCandidate:R YangFull Text:PDF
GTID:2428330578956295Subject:Control engineering
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Multi-axis force sensor is widely applied in scientific test and industrial production.With the development of technology,more and more occasions need dynamic force measurement,and thus put forward high requirements on the dynamic characteristics of the multi-axis force sensor.However,currently,the most commonly used strain multiaxis force sensor usually possesses low dynamic response speed,high overshoot and cross-axis dynamic coupling interference,which cannot meet the requirements of dynamic testing.Accordingly,the dissertation maily studies the dynamic characteristic of strain multi-axis force sensor and proposes improved dynamic compensation,decoupling and calibration methods to solve the problems usually come out in the existing methods..For the sensor dynamic compensation,a new dynamic compensation method based on system identification and error-overrun(EOV)mode correction is proposed to solve the problem that the existing compensation method though can improve the time-domain tracking performance but sometimes fail to widen the frequency-domain measurement bandwidth of the sensor simultaneously.For the new method,sensor dynamic compensation is divided into primary and secondary compensations.Primary compensator is obtained by system identification method for correcting the full frequency response of the sensor,secondary compensator is constructed as a uniform structure to purposely correcting each of the remaining EOV modes that limit the sensor measurement bandwidth.Specifically,construction methods of four categories of secondary compensators are discussed;circular construction of multiple secondary compensators and sequential dynamic compensation of sensor output are presented.For dynamic decoupling-compensation,an iterative dynamic decoupling-compensation method based on pre-matrix is proposed;that is,iterative dynamic decoupling of the sensor output is first conducted to reduce the sensor cross-axis dynamic coupling interference,and then the dynamic compensation is carried out to reduce the dynamic error of the sensor main channel dynamic error.For the method,the convergence of the iterative dynamic decoupling process is mainly studied.Speciffically,for the problem that the existing iterative dynamic decoupling method may not converge in the application,a pre-matrix P(diagonal matrix)is introduced to change the amplitude of the sensor coupling matrix at some frequency points,so as to improve the convergence of iterative decoupling.Moreover,the dissertation also proposes a improved dynamic calibration method for the force sensor;that is,replace human hand with an designed impact shear device to shear the steel wire to generate a step force/torque for dynamically calibrating the sensor,and measure the step edge duration time of the step signal by a designed measurement circuit,so as to improve the dynamic calibration accuracy of the sensor and thus provide better basis for future research on the sensor dynamic characteristic.Finally,based on the dynamic calibration experimental data of a multi-axis force/torque sensor ATI Mini45,the effectiveness of the above method is verified.The results show that: after dynamic decoupling-compensation,the dynamic coupling ratio and the rootmean-square error of the coupling interference in the sensor force and torque directions all are decreased by more than 70%;the step response adjust times of the sensor six channels are shortened from a few hundred milliseconds to within 3 ms,step overshoots are reduced from more than 80% to less than 5%,and the measurement bandwidths are widened from around 30 Hz to around 100 Hz.Thus,the proposed dynamic calibration methods in the dissertation are feasible and effective.In addition,the step unloading test of the sensor ATI Mini45 also shows that the improved dynamic calibration method can effectively improve the sensor dynamic calibration accuracy.
Keywords/Search Tags:Strain multi-axis force sensor, Dynamic error, Dynamic correction, Dynamic decoupling, Dynamic calibration
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