Design And Development Of A Subway Assisted Travel System For Visually Impaired Passengers

With the rapid advancement of China's modernization process,urban infrastructure construction is becoming more and more complete,public transportation is becoming more and more convenient,and the subway has become an important part of public transportation.But for the visually impaired,who make up nearly one percent of our population,travelling by subway is extremely difficult.In order to solve this problem,this paper designs a subway auxiliary travel system for visually impaired passengers to provide them with accurate humanized navigation service.The main research contents include:First,the functional requirements and performance requirements of the system for visually impaired passengers are analyzed.On this basis,the overall design,hardware selection and software architecture of the system are completed.Secondly,the spatial perception of visually impaired passengers and the environmental and structural characteristics of subway stations are analyzed,and a construction method of subway station internal environment model based on the spatial perception ability of the visually impaired passengers is proposed.The single-layer topology model is built by filtering the spatial elements of the CAD map,marking key points and extracting the paths.The multi-layer topology model of subway station can be obtained by connecting the topology model of each single layer with the connecting element such as stairs or lifts.Semantic information is extended to the model,so as to improve the visual impaired passengers' perception of the subway environment.Then,the key factors restricting the positioning accuracy in subway station and common indoor positioning technology are analyzed.An algorithm based on adaptive square root unscented kalman filter is proposed to locate visually impaired passengers in subway station.This algorithm combines the UWB location model and the implement method of mobile phone's MEMS for pedestrian dead reckoning,and fuses the PDR information with the UWB data,which using the excellent high frequency characteristics of PDR to suppress NLo S error generated by the UWB model,to get the accurate position of the pedestrians in the subway station.Subsequently,the navigation scheme of the system is designed.Two evaluation indexes of distance and safety are put forward.Using the analytic hierarchy process(AHP)which aims to solve the multi-objective decision problems,calculates the comprehensive weights of each influencing factor,so as to get the weight of the paths.The Dijkstra method is used to calculate the optimal path.And for a better human-computer interaction experience,a multi-mode navigation method combining text,graphics,speech and spatial audio is proposed.The problem of multi-layer space navigation in subway station is solved.Finally,an experimental system is set up according to the design scheme of this article,including hardware deployment and software design of server and client based on C# and Java respectively.The positioning and navigation functions of the system are tested,and the overall joint debugging of the system is completed,which verifies the feasibility and effectiveness of the system.