In advanced vehicle control and safety systems, position measurement is an important link for the identification of vehicle locations, such as lateral position relative to a lane or a desired trajectory. Technologies developed for such purposes include electrically powered wire, computer vision, magnetic sensing, optical sensing, inertia navigation, and global positioning systems. This paper focuses on magnetic sensing systems that are used for ground vehicle control and guidance. The magnetic fields from sample magnets are first measured to determine the characteristics of their patterns as the basis for detection and position identification. The effects of external objects, such as rebar or scraped metals on roadways, are then assessed with a random selection of potential objects. Tests are also conducted in a variety of infrastructure locations to observe the probable impacts from the earth fields on the recognition of magnet field patterns. Also presented in the paper is a discussion of sensing algorithms applicable to the sensing of magnets and their use for vehicle guidance. Exemplary measurements are shown to illustrate sensing approaches that have been considered or developed in real-time applications. Implications from different sensing algorithms regarding sensitivity to measurement variations are also reviewed. A list of design objectives and constraints for components of a magnetic sensing system is outlined as the basis for its optimization. With successful demonstrations in several applications and different operating environments, position measurements using magnetic markers have proven to be an appropriate candidate for ground vehicle guidance and control. For system-wide deployment of similar technologies, the subject deserves further investigations into broader issues such as system durability and total costs in conjunction with continual improvements in accuracy and reliability of sensing capabilities.
