Research On Key Issues Of Elevator Car Location Awareness Radar

The elevator technology has been growing with a higher demand for elevator oper-ation speed,effeciency and its comfort when passengers ridding.However,the conven-tional elevator monitoring system is open-loop controlled,which is an inherent flaw and such a critical issue brings threats to passengers' safety and requires to be solved.The main challenge of elevator close-loop control and elevator monitor is to obtain the information on the position and speed of an elevator car.This thesis focuses on such kind of problem and seeks for the application of microwave radar.Moreover,it studies key issues in multipath and clutter suppressing when a microwave radar is to use into a lift shaft.This thesis introduces the ray tracing method for the modelization of the propaga-tion properties of electromagnetic waves when they propagate in such a unique tunnel scenario,and then the issues of multipath and clutter are analyzed.As for multipath,this thesis presents a frequency diverse method and then it is demonstrated and validated by simulation results.As for background clutter in a lift shaft,it is static,which leaves the conventional clutter suppressing method of conventional radar invalid.To solve this problem,this thesis presents a method using the information of polarization.The background clutter in a lift shaft is from plane reflection,therefore,it contains strong cross-polarisation energy.This thesis presents and demonstrates the limitation of conventional cluttering suppressing methods using polarization information and then it proposes a clutter suppressing method based on orthogonal polarization character of a specially designed transceiver for secondary radar.The simulation results show validation of the proposed method in solving the issue of such kind of static clutter suppressing.This thesis designs a prototype of an elevator car position sensing radar.After polar-ization calibration,a practical experiment is presented in a tunnel scenario which shows the same character with a lift shaft scenario.The results show validation and feasibility of clutter and multipath suppressing methods presented in this thesis.As a conclusion,the content of this paper lays a theoretical and practical foundation for the application of a microwave radar in the elevator monitoring scenario.