| With the development of industrial manufacturing,aerospace and infrastructure,3D precision measurement technology and instruments are constantly evolving and innovating.From the coordinate measuring machines,theodolites to the emerging indoor GPS(i GPS or w MPS)and laser vision measurement technology in recent years,ways of 3D precision measurement are diversified.Considering the current limitations of application of existing measurement methods in the industrial field of conventional size,a new type of joint type laser sensor consisting of four small harmonic turntables,two collimating lasers and a high resolution imaging system is proposed.A non-orthogonal shafting architecture is used in the new sensor that costs of instrument manufacturing and maintenance are greatly reduced.The rotating shaft of the sensor is composed of small harmonic turntables,and the measurement accuracy of the sensor space coordinates is directly determined by its positioning accuracy,so positioning error calibration and compensation of the single-axis turntable are essential.In order to solve the problem of positioning error calibration of the small harmonic turntable,a method for measuring and compensating the rotation angle of single-degree-of-freedom small harmonic turntable based on Renishaw dual-frequency laser interferometer is proposed.Firstly,based on the principle of laser interference angle measurement and optical path adjustment,the angle measurement system is established.The influence of assembly error of measurement system on angle measurement accuracy is analyzed and the rotary table is adjusted effectively.Then,the angle calibration experiment scheme of small harmonic turntable is proposed.Finally,the curve fitting method is used to analyze the measurement data of the turning angle error.The error compensation function is embedded in the controller,real-time and effective compensation for angle error of turntable is realized.The experimental results show the method can improve the positioning accuracy of the small harmonic turntable by more than 85%,and the positioning error of turntable after compensation is less than 10?.This method can be used to calibrate the small harmonic turntable with small interval.Through using the small-interval subdivision calibration in 360°,positioning accuracy of the turntable meets the three-dimensional measurement accuracy requirements of the joint type laser sensor.The main contents of this thesis are as follows:1.The present research status of angle measurement technology and the method of position error compensation of turntable are analyzed.According to the technical indicators of joint type laser sensor,performance parameters of the single-axis turntable are researched and the turntable is selected,and the source of transmission error of harmonic turntable is analyzed.The abstract model of the articulated 3D laser sensor is built on Solid Works based on the selected harmonic turntable.2.According to the principle of angle measurement of dual-frequency laser interferometer and optical path construction,the construction of optical path system and optical path adjustment are completed.According to the period of the harmonic turntable transmission,the calibration and compensation control scheme are designed.3.The GUM method is used to evaluate the measurement uncertainty of the turntable positioning error measurement system,the reliability of the calibration result is verified.4.The harmonic turntable control program is developed twice based on MFC,and automatic rotation of the turntable is realized.The measurement efficiency is greatly improved compared with the original manual control.5.The system of harmonic turntable angle measurement is built.The compensation program of rotation angle positioning error is programmed,the real-time compensation of the rotation angle of the harmonic turntable is realized. |
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