Robust Positioning Algorithm for a Yard Transporter Using GPS Signals with a Modified FDI and HDOP

Abstract

This paper proposes a robust positioning algorithm using a modified fault detection and isolation (FDI) algorithm and the horizontal dilution of precision (HDOP) for localising a yard transporter using the global positioning system (GPS). In conventional approaches, each GPS signal received is analysed to determine if it is contaminated and only the clean signals are used for positioning the current location. This feasibility test is called an FDI scheme, and it is commonly used in commercial GPS receivers, where only the signal-to-noise ratio (SNR) is used to detect false GPS signals. On the other hand, in urban environments or near buildings, the selection of satellite signals by the SNR only is unreliable, which results in an insufficient number of satellite signals to position a transporter at a certain moment. This paper proposes a modified FDI algorithm that detects and isolates faulty signals using the SNR, the measurement quality indicator (mesQI), and the Doppler shift in sequence to improve the reliability of selecting good satellite signals and improving the positioning accuracy. In addition, the HDOP was adopted to improve the accuracy and reliability further. The effectiveness of the proposed algorithm was assessed by experiments with a mobile robot to simulate a transporter in a shipbuilding yard.