Performance and Technology Comparison of GMR Versus Commonly used Angle Sensor Principles for Automotive Applications 2007-01-0397

Position detection and control is necessary in modern automotive applications because of remotely controlled actuators, such as window lifters or windshield. In recent years, the demand for reliable actuators for safety critical systems, such as power steering systems, has also increased significantly. This creates a growing demand for fast, accurate and efficient servo motor systems that are increasingly smarter, smaller and cheaper. One interesting option is to use Giant Magneto Resistive (GMR) angle sensors to replace the resolvers, Hall, inductive and Anisotropic Magneto Resistive Effect (AMR) Sensors commonly used today for shaft-angle measurements. In principle, there are functional differences among various angle measurement technologies; thus, the effect of switching between them needs to be analyzed. In particular, the accuracy, resolution, measurement rate, signal delay, temperature resistance and the system partitioning need to be discussed relative to the application requirements. In this paper, the individual influences of these parameters on applications are shown and compared to each other. The advantages and disadvantages of GMR, compared to the widely used sensors, are described in order to provide guidance for future application decisions. Some applications, such as Throttle Control, Steering Angle Measurement Systems and Electrical Commutated Motor Drives (EC-Motors), are discussed in detail. Conclusions are presented regarding the potential improvement deriving from the use of GMR rather than the angle sensor technologies commonly used today.