An Inexpensive and Accurate Absolute Position Sensor for Driving Assistance

An inexpensive accurate absolute position sensor has been developed as a result of this study to improve the reliability of automobile navigation systems. The conventional navigation system utilizes the Global Positioning System (GPS) and rate gyroscope signal for localization, which suffers from accumulated errors and the high price of the rate gyroscope. To resolve these problems, an electronic compass can be utilized instead of the rate gyroscope for the navigation system. On account of its sensitivity against external magnetic interference, the electronic compass itself is not accurate enough to be used for localization compared to the rate gyroscope. To overcome this shortcoming, in this paper, a robust electronic compass is designed by using two electronic compasses to efficiently cancel out the low-frequency interference. That is, a dual compass system with a linear estimation algorithm against irregular and long-lasting magnetic interference has recently been proposed and implemented. When the external magnetic interference can be eliminated from the electronic compass, it becomes much more accurate than the gyroscope-based system, which suffers from the accumulative drift error. The reliability and performance of the designed system have been verified through real navigation experiments.

I. Introduction

Hybrid navigation systems that incorporate a Global Positioning System (GPS) receiver and dead-reckoning (DR) sensors have been widely used for automobile navigation systems [1]–[4]. There are two general DR sensors to detect the azimuth angle using terrestrial magnetism: 1) a rate gyroscope and 2) an electronic compass [5]. A rate gyroscope is accurate in representing the attitude of a vehicle for a short period of time; however, the errors are accumulative and drifty, and the price is very high, particularly for high performance. The electronic compass is a cheap tool for representing the azimuth angle. However, it has measurement errors that are sensitive to external interference [6]–[11]. On the contrary, the rate gyroscope suffers from accumulative errors and from drift with time, although it is robust against external magnetic interference. Therefore, it is necessary to calibrate the sensor every few minutes [5].