Reasearch On SAW RFID Localization System For Ladle Hoisting

The transportation of steel ladle is the basic element of steelmaking production.The two hooks of gantry crane are hung on the lifting lugs on both sides of the ladle to hoist and transport it.Before the ladle hosting,the reiable matching between the hook and the lug should be strictly controlled,otherwise the huge power of the gantry crane will cause the steel ladle to capsize and result in major accidents.Presently,the operator of a gantry crane needs to continuously adjust the position of the hook under auxiliary commands of the ground staff in order to match the hook and lug.Manual adjustment is fairly inefficient,and its possibility of misjudgement introduces serious possible security risks.Therefore,above issues demand further researchs to make the steelmaking production safe and efficient.The key to the reliable matching between hook and lug is to align them before hoisting the ladle.Based on surface acoustic wave radio frequency identification(SAW RFID)localization,the positions of the hook and the lug are estimated by attaching SAW tags to them.Afterwards,whether to hoist the ladle or adjust the hook's position is determined by the relative position between hook and lug,thus reaching reliable matching and guaranteeing safety and efficiency of production.Correspondingly,the research contents of the thesis are as follows:(1)SAW RFID localization technologies with higher accuracy are studied.The spatial resolution and theorical localization accuracy of SAW tag's signal features,such as time-delay,signal strength and phase are discussed.For phase-based localization with higher accuracy,phase biases from hardware and phase errors from interference are analyzed,and corresponding compensation and suppression methods are introduced to ensure the accuracy of backscattered phase and localization.Then SAW RFID localization methods based on hypobola,velocity,angle of arrival,location fingerprint and synthetic aperture are studied,which could achive higher localization accuracy with phase 2?ambiguity,and the mechanism and features of these methods are discussed.(2)Reliable matching method of hook and lug based on SAW RFID localization is proposed.By analyzing the matching process,the position conditions of hook and lug for their reliable matching is obtained,with which realiable matching process can be achived by localization.Combining the real scene and hardware setup,lug localization method based on geometric mapping and hook localization method based on synthetic aperture are proposed,which realize the localization of hook and lug employing only two SAW tags and two reader antennas.Meanwhile,numberical simulations are carried out to verify the localization accuracy,and the accuracy is imporved further by compensating innate error of geometric mapping and deviation error of synthetic aperture's template,which achives the required accuracy with no more than 20° phase error.(3)Considering the characteristics of SAW RFID localization for steel ladle hoisting,the designs of SAW tag and SAW RFID reader are optimized,and the actual performances of optimized tag and reader are tested.At the same time,the comprehensive performance of SAW tag under the ladle's high temperature is tested with heating experiments.Moreover,the localization accuracy of proposed method is verified to meet the matching requirement by carrying out hook and lug localization experiments.In regard of the matching between hook and lug,SAW RFID localization technologies and the improvement of accuracy are studied.Then reliable matching method of the hook and lug based on SAW RFID localization is proposed.And the relavant hardwares are developed.The proposed method and the localization system,employing only two SAW tag and two reader antennas,can achive reliable matching of hook and lug quickly and cost-effectively,thus ensuring safety and efficiency of steelmaking.