Localization for visually impaired people in dynamically changing environments with unexpected hazards and obstacles is a current need. Many techniques have been discussed in the literature with respect to location-ba...Localization for visually impaired people in dynamically changing environments with unexpected hazards and obstacles is a current need. Many techniques have been discussed in the literature with respect to location-based services and techniques used for the positioning of devices. Time difference of arrival (TDOA), time of arrival (TOA) and received signal strength (RSS) have been widely used for the positioning but narrow band signals such as Bluetooth cannot efficiently utilize TDOA or TOA. Received signal strength indicator (RSSI) to measure RSS, has been found to be more reliable. RSSI measurement estimations depend heavily on the environmental interference. RSSI measurement estimations of Bluetooth systems can be improved either by improving the existing methodologies used to implement them or by using fusion techniques that employ Kalman filters to combine more than one RSSI method to improve the results significantly. This paper focuses on improving the existing methodology of measuring RSSI by proposing a new method using trilateration for localization of Bluetooth devices for visually impaired people. To validate the new method, class 2 Bluetooth devices (Blue Giga WT-12) were used with an evaluation board. The software required was developed in National Instruments LabView. The PCB was designed and manufactured as well. Experiments were then conducted, and surface plots of Bluetooth modules were obtained to show the signal interference and other environmental effects. Lastly, the results were discussed, and relevant conclusions were drawn.展开更多
Calculation of assembly clearance is the basis of analysis on assembly problems,and the real assembly surface is the nonideal surface.In this paper,the concept of assembly clearance on nonideal surface is defined and...Calculation of assembly clearance is the basis of analysis on assembly problems,and the real assembly surface is the nonideal surface.In this paper,the concept of assembly clearance on nonideal surface is defined and the calculation algorithm of assembly clearance is designed.Based on the calculation,the concept of clearance surface is put forward to express the distribution of assembly clearance on nonideal surface as it can assist the analysis of assembly problems.Finally,the effectiveness of the algorithm is verified by the calculation of the assembly clearance between the surfaces of piston and cylinder.展开更多
文摘Localization for visually impaired people in dynamically changing environments with unexpected hazards and obstacles is a current need. Many techniques have been discussed in the literature with respect to location-based services and techniques used for the positioning of devices. Time difference of arrival (TDOA), time of arrival (TOA) and received signal strength (RSS) have been widely used for the positioning but narrow band signals such as Bluetooth cannot efficiently utilize TDOA or TOA. Received signal strength indicator (RSSI) to measure RSS, has been found to be more reliable. RSSI measurement estimations depend heavily on the environmental interference. RSSI measurement estimations of Bluetooth systems can be improved either by improving the existing methodologies used to implement them or by using fusion techniques that employ Kalman filters to combine more than one RSSI method to improve the results significantly. This paper focuses on improving the existing methodology of measuring RSSI by proposing a new method using trilateration for localization of Bluetooth devices for visually impaired people. To validate the new method, class 2 Bluetooth devices (Blue Giga WT-12) were used with an evaluation board. The software required was developed in National Instruments LabView. The PCB was designed and manufactured as well. Experiments were then conducted, and surface plots of Bluetooth modules were obtained to show the signal interference and other environmental effects. Lastly, the results were discussed, and relevant conclusions were drawn.
基金National Natural Science Foundation of China(Grant No.51575031)the key program of the Engineering Research Center of Complex Product Advanced Manufacturing System,Ministry of Education.
文摘Calculation of assembly clearance is the basis of analysis on assembly problems,and the real assembly surface is the nonideal surface.In this paper,the concept of assembly clearance on nonideal surface is defined and the calculation algorithm of assembly clearance is designed.Based on the calculation,the concept of clearance surface is put forward to express the distribution of assembly clearance on nonideal surface as it can assist the analysis of assembly problems.Finally,the effectiveness of the algorithm is verified by the calculation of the assembly clearance between the surfaces of piston and cylinder.
