Impact Assessment of Various IMU Error Sources on the Relative Accuracy of the GNSS/INS Systems

GNSS/INS relative accuracy, which characterizes error variation or instability on different time/spatial scales, is increasingly required in some new applications, such as precise surveying and mapping, especially to represent the details of error variation over the short term for precise relative measurement. The INS, as an important GNSS/INS systems component, can provide high navigation accuracy over the short term, but INS navigation accuracy decreases with time due to IMU error sources, which might have a great influence on the GNSS/INS relative accuracy. This paper focuses on the impact assessment of IMU errors on GNSS/INS relative accuracy and proposes a hybrid simulation scheme based on signal grafting to analyze the impact of each IMU error on the relative accuracy. Allan variance, as one of the evaluation methods of GNSS/INS relative accuracy, is applied. The results show that the white noise of the gyroscope and accelerometer is the major factor affecting the GNSS/INS short-term accuracy, and the backward smoothing solution can further reduce the impact of nonwhite noise. This work can provide a reference for sensor selection and facilitate the use of low-end IMUs in applications with high demand for short-term relative accuracy.