Analysis of driver's steering and speed control strategies in curve negotiation.

Abstract

The paper discusses some of the common speed and steering control strategies of drivers for negotiating curved roads under normal, obstacle-free driving conditions. An analysis is given of the dynamic behaviour of the driver-vehicle system for two typical strategies. A driver model is developed to take into account the application of steering and speed control before approaching a curve and during driving on curved roads, The driver's anticipatory speed-control is based on the desired lateral acceleration and estimated maximum curvature of the road ahead. The well-known two-level model is adapted for describing the steering activity of the driver. The primary control of steering is anticipatory tracking of the road-curvature previewed at a look-ahead distance. It is assumed that the driver's mental model for anticipatory steering is based on a simple, linear and non-adaptive vehicle model assuming a vehicle driving with constant forward speed. A non-linear model with variable forward speed represents the actual vehicle. When both steering input and speed control using brake/throttle are applied simultaneously the driver's anticipatory steering estimate leads to tracking errors. The driver's compensatory steering input for reducing tracking errors uses feedback of error in lateral displacement at a near-field viewpoint of the driver. The results of analysis of the driver-vehicle system demonstrate the significant influence of the driver's internal model and control strategies on the overall performance of the driver-vehicle system.