Current Issue : April - June Volume : 2012 Issue Number : 2 Articles : 5 Articles
This paper presents a sequential fault detection and identification algorithm for detecting a fault in a vehicle�s ultrasonic parking\nsensors. The algorithm identifies a bias fault in any of the ultrasonic sensors by computing the probability of having that bias fault\ngiven a carefully constructed measurement residual that is only a function of the measurement noise and the possible measurement\nfault. A set of bias hypotheses is assumed and initially given equal alarm probability. It is assumed that only one sensor will acquire\na bias at any given time. Once the probability of a hypothesis approaches 1, that hypothesis is declared as the correct hypothesis\nand the bias associated with the hypothesis is removed from the sensors� reading. The accuracy and convergence characteristics\nof the proposed algorithm are verified using experimental results. This study is essential to ensure accurate operation of vehicle�s\nultrasonic parking sensors....
Owing to their complimentary characteristics, global positioning system (GPS) and inertial navigation system (INS) are integrated,\r\ntraditionally through Kalman filter (KF), to obtain improved navigational solution. To reduce the overall cost of the system,\r\nmicroelectromechanical system- (MEMS-) based INS is utilized. One of the approaches is to reduce the number of low-cost\r\ninertial sensors, decreasing their error contribution which leads to a reduced inertial sensor system (RISS). This paper uses KF\r\nto integrate GPS and 3D RISS in a loosely coupled fashion to enhance navigational solution while further improvement is achieved\r\nby augmenting it with map matching (MM). The 3D RISS consists of only one gyroscope and two accelerometers along with the\r\nvehicle�s built-in odometer. MM limits the error growth during GPS outages by restricting the predicted positions to the road\r\nnetworks. The performance of proposed method is compared with KF-only 3D RISS/GPS integration to demonstrate the efficacy\r\nof the proposed technique....
The upcoming Galileo global navigation satellite system has a design problem with the cosine-phased BOCc(15, 2.5) modulation\nof its Public Regulated Service (PRS A-code). This signal needs far more bandwidth than the available 40.92 MHz. The present\nsignal and system specification cannot be expected to deliver design performance under practical operational conditions (noise,\nreceiver phase distortion, and multipath). There would not have been this problem with sine-phased BOC(15, 2.5)....
Indoor wireless localisation is a widely sought feature for use in logistics, health, and social networking applications. Low-powered\r\nlocalisation will become important for the next generation of pervasive media applications that operate on mobile platforms. We\r\npresent an inexpensive and robust context-aware tracking system that can track the position of users in an indoor environment,\r\nusing a wireless smart meter network. Our context-aware tracking system combines wireless trilateration with a dynamic position\r\ntracking model and a probability density map to estimate indoor positions. The localisation network consisted of power meter\r\nnodes placed at known positions in a building. The power meter nodes are tracked by mobile nodes which are carried by users to\r\nlocalise their position.We conducted an extensive trial of the context-aware tracking system and performed a comparison analysis\r\nwith existing localisation techniques. The context-aware tracking system was able to localise a person�s indoor position with an average\r\nerror of 1.21 m....
The carrier-phase-derived delta pseudorange measurements are often used for velocity determination. However, it is a type of\r\nintegrated measurements with errors strongly related to pseudorange errors at the start and end of the integration interval.\r\nConventional methods circumvent these errors with approximations, which may lead to large velocity estimation errors in highdynamic\r\napplications. In this paper, we employ the extra states to ââ?¬Å?rememberââ?¬Â the pseudorange errors at the start point of the\r\nintegration interval. Sequential processing is employed for reducing the processing load. Simulations are performed based on\r\na field-collected UAV trajectory. Numerical results show that the correct handling of errors involved in the delta pseudorange\r\nmeasurements is critical for high-dynamic applications. Besides, sequential processing can update different types of measurements\r\nwithout degrading the system estimation accuracy, if certain conditions are met....
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