Characterization of magnetic tape and magnetic markers as a position sensing system for vehicle guidance and control

In the studies of advanced vehicle control and safety systems, position measurement is an important link that provides essential information for the identification of vehicle locations. One type of critical information used by vehicle control systems is the measurement of lateral position relative to a lane or a desired trajectory. Among the technologies that have been developed for such purposes are electrically powered wire, computer vision, magnetic sensing, optical sensing, inertia navigation and global positioning systems. The paper focuses on two types of magnetic systems that have been experimentally demonstrated in earlier years. The objective is to identify the characteristics of these two sensing systems and to offer a comparison of their distinct features. Experimental data from the measurement of the magnetic fields around tape and marker systems are shown to illustrate their characteristics and functioning principles. The magnetic markers are implemented by a series of magnetic pieces installed under the road surface at a specified spacing along the subject trajectory. The magnetic tape embeds magnetic materials in a thin and narrow strip, which is laid on or under the surface of a roadway. The two systems exhibit distinct features in their field patterns, yet they possess similar properties that can be identified with sensing algorithms. Also presented in the paper is a preliminary assessment of the two systems for the use of vehicle control and safety systems. The criteria to be considered in evaluation include accuracy, range, reliability, durability, applicability, and economic costs.