Driver/Vehicle Modeling and Simulation

This paper describes the driver/vehicle modeling aspects of a computer simulation that can respond to highway engineering descriptions of roadways. The driver model interacts with a complete vehicle dynamics model that has been described previously. The roadway path is described in terms of horizontal and vertical curvature and cross slopes of lanes, shoulders, side slopes and ditches. Terrain queries are made by the vehicle dynamics to locate tires on the roadway cross-section, and to define vehicle path and road curvature at some distance down the road. The driver model controls steering to maintain lateral lane position. Speed is maintained at a speed limit on tangents, and decreased as needed to maintain safe lateral acceleration. Because the bandwidth of longitudinal (speed) control is much lower than lateral/directional (steering) control, the driver model looks further ahead for speed control than for steering.

The paper considers numerous examples of the path and speed control ability of the driver model in response to horizontal and vertical curvature. The driver model must slow down, and brake if necessary, to avoid excessive lateral acceleration during cornering. The driver model must also respond with shifting if need be to accommodate vertical grade. Examples include passenger car and tractor/semi-trailer cases, and sensitivity analysis is used to demonstrate the influence of driver model parameters.