Abstract
In the 1980s, Global Positioning System (GPS) receiver autonomous integrity monitoring (RAIM) was proposed to provide the integrity of a navigation system by checking the consistency of GPS measurements. However, during the approach and landing phase of a flight path, where there is often low GPS visibility conditions, the performance of the existing RAIM method may not meet the stringent aviation requirements for availability and integrity due to insufficient observations. To solve this problem, a new RAIM method, named vision-aided RAIM (VA-RAIM), is proposed for GPS integrity monitoring in the approach and landing phase. By introducing landmarks as pseudo-satellites, the VA-RAIM enriches the navigation observations to improve the performance of RAIM. In the method, a computer vision system photographs and matches these landmarks to obtain additional measurements for navigation. Nevertheless, the challenging issue is that such additional measurements may suffer from vision errors. To ensure the reliability of the vision measurements, a GPS-based calibration algorithm is presented to reduce the time-invariant part of the vision errors. Then, the calibrated vision measurements are integrated with the GPS observations for integrity monitoring. Simulation results show that the VA-RAIM outperforms the conventional RAIM with a higher level of availability and fault detection rate.
Highlights
With the wide utilization of satellite navigation technology, the integrity of navigation solutions has become a major issue, especially for safety-of-life applications [1,2,3]
Since the scenario of this paper focuses on the approach and landing phase that is a low Global Positioning System (GPS) visibility, the probability of multi-fault simultaneity is less than the integrity requirement 10−7 and can be ignored in applications
We have proposed a VA-Receiver autonomous integrity monitoring (RAIM) for GPS integrity monitoring in approach and landing phase
Summary
With the wide utilization of satellite navigation technology, the integrity of navigation solutions has become a major issue, especially for safety-of-life applications [1,2,3]. As an approach and landing phase is a typical part of a flight path with unsafe incidents, designing a suitable RAIM procedure is especially important to guarantee flight safety. The performance of RAIM relies on a sufficient number of visible satellites and a fine geometrical configuration to check the consistency of the measurements. Since the approach and landing phase is usually consistent with low GPS visibility conditions due to obstructions, there is a larger mask angle leading to insufficient visible satellites and a poor geometrical configuration. The availability and fault detection performance of RAIM will decrease dramatically [4,5,6]. It is essential to further investigate the RAIM methods in the approach and landing phase
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