Page - 149 - in Maximum Tire-Road Friction Coefficient Estimation

E Longitudinal velocity estimation The standard GNSS receiver update is 1 Hz, which is sufficient for automotive nav- igation, [SZZ13], but not to determine the vehicle speed for the proposed application. Although technically feasible receiver rates go up to 200 Hz (e.g. for aeronautic appli- cations), [SZZ13], these systems are not affordable for automotive series application. In addition, these rates only apply in ideal conditions (e.g. good satellite visibility). Espe- cially in urban areas, GNSS outage is inevitable. In combination with measurements of the vehicle’s state, both the calculation of position and velocity can be significantly im- provedand, incaseofGNSSoutage, also temporarilydelivervx estimateswithoutGNSS velocity. Manyapproachescanbe found in literature tocombineGNSSand inertialmea- surements, oftenbyusingaKalmanfilter. Forexample,Hide et al. achievedgoodresults for high-accuracy real-time navigation using a low-cost micro-electromechanical system (MEMS) as a sensor to measure accelerations and angular rates with an update rate of 100HzandaGNSSwithareceiverupdateof1HzwithaKalmanfilter, [HMS03]. Thus, combined with additional on-board sensor information, GNSS-velocity-based estimators show promising results. 149