Abstract: In some RFID based indoor real-time locating applications,because of the complexity of the scene and the limited accuracy of the RTLS,there are some abnormalities in the object’s trail reported by RTLS,such as objects going through walls.An efficient data filtration method was presented to avoid such abnormality.First,the scene is mapped into a discrete model which is represented by a “gray image”.Each pixel of the image represents a point of the scene,and the grayscale of each pixel represents different regions/rooms,walls and doors.During real time locating,two of the object’s consecutive scene coordinates are mapped to two pixels respectively.The grayscales of the pixels on the segment connecting theses two pixels are used to judge whether there is an abnormality or not,and the object’s coordinates in image are rectified.Finally,the rectified coordinates are mapped back to the scene coordinates.Experimental results show that our method is fast and efficient,and can avoid such abnormality.

Key words: Radio frequency identification,Active RFID,Real-time location system,Middleware,Data filtration