Automatic cruise control modeling- a lattice PWL approximation approach

Approximation and control of nonlinear systems is a very important field of research for systems analysis and design. Although there is a growing interest in modeling and compact representation of piecewise linear functions as seen in the recent research, however only limited applications exist in the literature. In this paper a systematic procedure is outlined for modeling a nonlinear system with continuous piecewise linear function. The scheme is applied to approximate the nonlinear vehicle following model, where a third-order nonlinear system is considered to model the vehicle and power train dynamics. It is shown that without facing the problem of curse of dimensionality in linear models, the approximated model is compact, captures essential vehicle dynamics and is suitable for further control by linear methods. The control is implemented on local linear models based on gain scheduling technique. Simulation examples show that the designed system not only guarantees asymptotic tracking of the desired trajectories, but also ensures safety and ride comfort under the constraints of physical limitations inherent in the system. Various issues of vehicle following e.g. convergence of error in the inter-vehicle spacing, velocity following and control saturation are addressed in this paper. The performance analysis reveals that the new strategy yields valid results