Research On Information Fusion Technique Of Multi Rolling-wheel High Precision On-line Measurement System

By the development of technique and continuous improvement of mechanism produce ability, the produced workpiece's space dimension becomes bigger and bigger, and the produce precision becomes higher and higher, so the demand of detection technique is higher and higher. Because large axis-hole workpiece has the characters of large bulk, high thermal capacity and hard to achieve constant temperature, the online high precision diameter measurement is always a difficult technique problem. In so many large diameter measurement methods, rolling-wheel method is an easy method to achieve the large diameter on-line measurement, it can measure the infinity diameter in theory, but the traditional rolling-wheel method is impacted by skidding, rolling-wheel pressured distortion and temperature, the measurement accuracy is hard to improve. It can't meet the needs of modern mechanism produce industry, so Metrology of Military Industry in National Defense of China sets up a "tenth-five-year" project, which is the research of measurement method for large diameter high accuracy measurement system with multi-rolling wheels, solves the problem of large diameter on-line measurement. The project is on the basis of deeply analyzing the restriction of various factors to large diameter on-line measurement precision improvement with rolling-wheel method, develops the multi rolling-wheels large diameter measurement system constructed by new mechanism rolling-wheel. The system integrates the diameter measurement system and the roundness error measurement system, and amends the major errors of pressure distortion, temperature distortion, rolling-wheel rotation angle measurement error, skidding and the measured workpiece's radial pulsation, realizes high accuracy of on-line measurement to the large workpiece's diameter and roundness error. The dissertation research is focused on the information fusion of the multi rolling-wheel high precision on-line measurement system. The main research and innovation are as follows:1. It is analyzed to the major error sources and their characteristics influencing the large diameter and roundness error measurement accuracy. It is researched to the corresponding error identification, error separation and amendment method to the major error sources, which can eliminate or weaken the influence of the errors to the measurement results. The detail includes: the acquirement and amendment of rolling-wheel measure head round grating angle measurement error; the distinguish and compensation of rolling-wheel skidding; the on-line acquirement and amendment of rolling-wheel pressured distortion; the local amendment of the measured workpiece's distortion generated by cutting and environment temperature; the elimination of the measured workpiece's radial pulsation to the roundness error measurement.2. It is researched that the data fusion technique of getting high precision decision-making information from the same type redundant measurement information, providing the weight data fusion based mutual support method and threshold discriminance. To the data checked by mutual support detection, the method makes data fusion according to the sensor's character, automatically identifies and removes low-quality data of redundant measurement information, gets the higher accuracy measurement estimated value closer to the true value.3. For convenient on-line measurement, a control system based on embedded system ARM9 LPC3250 is designed to realize accurately control of the sampling timing to the multi-type and multiple sensors in on-line measurement system. The system is composed of power module, measurement circle control module, round grating signal processing model, micro-displacement sensor signal process model, temperature survey signal process model, pressure measure signal process model, simulation interface model, peripheral interface model, network communication model, others functional module and so on. The system can on-line acquire the diameter and roundness error of the large workpiece automatically and realize the intelligence operation & the functional expansion conveniently.4. In order to overcome the disadvantage of traditional rolling-wheel diameter measurement mechanism and add the roundness error synchronized measurement, a new multi rolling-wheel high accuracy large diameter measurement mechanism is developed. The measurement mechanism adopts rolling-wheel measure head having new structure, which reduces probability of skidding by adding a non-slip ring, real-time obtains measurement force information used to amend rolling-wheel pressured distortion by adding force measurement system and synchronously gets the roundness error information at the time of measuring diameter by adding micro-displacement sensor. The measurement mechanism realizes redundant measurement by installing three rolling-wheels with independent measurement function, and guarantees different install direction adjustment in structure used to horizontal workpiece and vertical workpiece measurement.5. For verifying correctness and validity of the researched data fusion method and calibrating the high precision characters of multi rolling-wheel measurement system, a simulation large axis system is designed to simulate the processing state of the measured large axis and finish all kinds of confirmatory and calibration experiments. The experiment result shows that the developed multi rolling-wheel large diameter measurement system can achieve the demanded function and precision.At present, many measurement instruments and systems is developing towards multi-functional, multi-information direction. The system integrates multi-type and multiple sensors, and mostly adopts redundant measurement scheme, so the dissertation research results can also be used to such equipments and systems as a reference.