ABSTRACT
The market for magnetic velocity sensors is expanding rapidly, particularly in the automotive industry where they are used in a variety of mechatronic systems such as antiskid braking systems (ABS), traction control (TC), four-wheel drive systems, etc. However, as the number of applications grows, the specifications these sensors are expected to meet are becoming more and more demanding. Larger signals are required to improve signalto-noise ratios and to relax manufacturing tolerances, thus lowering the cost. Despite the current interest in these sensors, the literature on the subject is insufficient and often limited to the description of a specific device (Foster 1988, Podeswa and Lachman 1989, Rowley and Stolfus 1990). Sometimes various technologies are compared (Ohshima and Akiyama 1989b), but because of the large number of possible approaches, the coverage of each concept remains overly general. In-depth analyses backed by theoretical frameworks are lacking, with some exceptions (Lequesne et al. 1996, Pawlak et al. 1991d, Ramsden 2001). Such analyses would allow us to understand and assess the relative importance of various design elements to the overall performance and provide the means for design optimization. They would not only be desirable, but also timely, because the emergence of new materials and manufacturing technologies holds the promise for improved configurations. This chapter attempts to fill this gap by providing both the theoretical background as well as practical optimization examples based on a number of novel sensor configurations.
