RAIM algorithm considering simultaneous multiple ramp failures

Purpose - The purpose of this paper is to develop and analyze a new multiple hypothesis receiver autonomous integrity monitoring (RAIM) algorithm, which can handle simultaneous multiple ramp failures. Design/methodology/approach - The proposed algorithm uses measurement residuals and satellite observation matrices of several consecutive epochs for failure detection and exclusion. It detects failures by monitoring the error vector rather than a projection of the error vector. The algorithm assumes that magnitude of range errors can vary with time, while the conventional sequential multiple hypothesis RAIM algorithm assumes that range errors are constant biases. Findings - The algorithm can detect any instance of multiple failures, including failures that cannot be detected by the conventional RAIM algorithm. It can detect multiple failures with magnitudes of several tens of meters, even though the algorithm must solve an ill-conditioned problem. And it can also deal with ramp failures which cannot be detected by conventional sequential multiple hypothesis RAIM algorithm. The detection capability of the proposed algorithm is not dependent on satellite geometry or types of errors. Practical implications - Implications for the development of the RAIM algorithm for aviation users are included. In particular, it can be a candidate for a future standard architecture in multiple constellations, multiple frequency and satellite-based augmentation system users. Originality/value - A new multiple hypothesis RAIM algorithm with a relative RAIM concept is proposed. Also presented is a detailed explanation of the algorithms, including rigorous mathematical expressions, and an analysis of differences in detection capability between the conventional multiple hypothesis RAIM algorithm and proposed algorithm.