Languages and Compilers for Parallel Computing 19th International Wo
The 19th Workshop on Languages and Compilers for Parallel Computing was heldinNovember2006inNewOrleans,LouisianaUSA.Morethan40researchers from around the world gathered together to present their latest results and to exchange ideas on topics ranging from
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Estimation of Road Profile and External Forces as Unknown Inputs
Abstract. This chapter is devoted to the application of sliding mode observers to estimate the unknown inputs of the road. Vehicle motion simulation accuracy, such as in accident reconstruction or vehicle controllability analysis on real roads, can be obtained only if valid road profile and tire-road friction models are available. Regarding road profiles, a new method based on Sliding Mode Observers has been developed and is compared to two inertial methods. Experimental results are shown and discussed to evaluate the robustness and the quality of the proposed approach.
5.1
Introduction
Road profile unevenness through road/vehicle dynamic interaction and vehicle vibration affects safety (tyre contact forces), ride comfort, energy consumption and wear. The road profile unevenness is consequently a basic information for road maintenance management systems [VP91]. In order to obtain this road profile, several methods have been developed. Measurement of road roughness has been a subject of numerous research for more than 70 years ([Har83], [MW86], [Mis90]). Methods developed can be classified into two types: response type and profiling method. Nowadays profiling methods giving a road profile along a measuring line are generally preferred. These methods belong to two basic techniques: rolling beam or inertial profiling method. The last method, which was first proposed in 1964 [SK64], is now used worldwide. Inertial profiling methods consist in analyzing the signal coming from displacement sensors and accelerometers ([Kar84], [GSH87]). One problem with the inertial profiling method, as currently used, is that it is impossible to build a 3D profile from elementary measurements needed for road/vehicle interaction simulation package. It is worthwhile mentioning that these methods do not take into consideration the dynamic behavior of the vehicle. However, it has been shown that modifications of the dynamic behavior may lead to biased results.
H. Imine et al.: Sliding Mode Based Analysis, LNCIS 414, pp. 83–102. c Springer-Verlag Berlin Heidelberg 2011 springerlink.com
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5 Estimation of Road Profile and External Forces as Unknown Inputs
Finding a way to get a 3D profile from the dynamic response of an instrumented car driven on a chosen road section is the general purpose of a research carried out at Roads and Bridges Central Laboratory (in French: LCPC) in cooperation with the Robotics Laboratory of Versailles (in French: LRV) [Imi03]. The proposed method estimates the unknown inputs of the system corresponding to the height of the road through the use of sliding mode observers ([BZ88], [XG88], [Dra92], [BBD96], [DBB99], [DB02]). Design of such observers requires a dynamic model. As a first step, a dynamic model of a vehicle is built up ([Men97], [Imi03]). This model has been experimentally validated comparing the estimated and measured dynamics in the response of a Peugeot 406 vehicle (as a test car). The longitudinal forces which depend on the road adhesion coefficien
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