Abstract
Appropriate fault isolation and system reconfiguration scheme is of great significance to ensure the reliability and precision of the tightly coupled global navigation satellite system/inertial navigation system (GNSS/INS). Currently, the commonly used methods include fault isolation method and fault adaptation method. However, the performance of them is not compared and analyzed fully in the existing literatures. In this paper, the principle of them is analyzed and the performance of them under different conditions is compared in theory firstly. On this basis, to improve the effectiveness and adaptability of fault detection and isolation, an adaptive fault isolation and system reconfiguration method is proposed. The radial basis function neural network (RBFNN) is used to predict the pseudo-GNSS measurement for the measurement reconfiguration. Besides, taking the variety of observation conditions into consideration, an adaptive adjustment criterion is introduced to realize the switch of fault isolation and measurement reconfiguration. The performance of the proposed method is verified and compared with the traditional methods by using the field test data. The results show that the fault isolation method can obtain higher filtering precision than the fault adaptation method in theory, compared with these two methods, the proposed method has better adaptability to the complex environment, and can improve the reliability and precision of the navigation system effectively.
Highlights
The tightly coupled integration of global navigation satellite system (GNSS) and inertial navigation system (INS) can achieve a superior performance to the single system as a result of the good complementary characteristics [1]
A new rate detector algorithm based on Autonomous Integrity Monitoring by Extrapolation (AIME) was developed in [12] and the test results show that it has better detection performance than AIME and Multiple Solution Separation (MSS) for gradual fault
ADAPTIVE FAULT ISOLATION AND SYSTEM RECONFIGURATION In terms of the above analysis, the results of the fault isolation method and fault adaptation method will be variant under different observation conditions
Summary
The tightly coupled integration of global navigation satellite system (GNSS) and inertial navigation system (INS) can achieve a superior performance to the single system as a result of the good complementary characteristics [1]. The performance of this method is affected by the satellite configuration and fault duration time [19], and the difference of the location of faulty measurements will lead to different filtering precision and fault detection results. Another fault isolation and system reconfiguration method is the detection, identification and adaptation (DIA) method [20], [21]. This method eliminates the presence of biases in the filtered state of the navigation system by estimating the model error. The state estimation at time k and its covariance matrix can be approximately expressed as
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