Mechatronic systems assist drivers in safe driving of cars more and more often. A vision of a totally automated car realizing many manoeuvres without driver’s participation becomes closer and closer. The lane change manoeuvre is one of the basic manoeuvres on the ground of which sequences of complex manoeuvres can be composed, e.g. vehicle passing or obstacle avoidance manoeuvre. For those reasons, automation of lane change manoeuvre appears to be essential for automation of vehicle driving and is a subject of numerous research studies. Within a research project, the authors have undertaken extensive analytical studies on application of active steering system EPS in automatic driving of a two-axis truck equipped with typical elements of ESC system and obstacle detectors, as well as road monitoring systems.

The present paper focuses on theoretical aspects of the synthesis of an automatic controller for the EPS active steering system. Simulation studies of an automatically controlled lane change manoeuvre illustrate the application of the methodology. The basis for theoretical considerations and numerical studies is the mathematic model of the controlled system (vehicle) and the controller. A complex, detailed description of the dynamics of a two-axis truck, taking into account nonlinearities and vehicle motion in 3D space, is included in the simulation model. The model of the controller is based on a reference model which is significantly simplified and hence is highly effective for carrying out necessary computations in real time. An algorithm of the controller operating as a Kalman regulator in a closed loop system is developed on the basis of this model. The time decomposition of the automatic control process into two phases –lateral displacement of the vehicle and stabilization of its position – is an essential, original distinguishing feature of the algorithm. Thanks to this decomposition, the structure of the control system is relatively simple. Feedback signals provided by the sensors available in a typical ESC system (lateral acceleration, yaw velocity) are used in the control process. The vehicle reference model and resulting control algorithms are presented in the paper. Simulation results refer to a two-axis truck travelling with a constant velocity on a straight, uniform road. At certain time instant the vehicle starts executing the lane change manoeuvre. Simulations were carried out for a number of cases with varying model parameters. That allowed estimating the sensitivity of the control algorithm to both perturbations of vehicle’s physical and operational parameters and to perturbations of parameters related to the obstacle. The results of simulations show that the proposed concept of the vehicle automatic control performs well in computational tests. The method of automatic execution of the lane change manoeuvre presented in the paper can offer an attractive alternative for vehicle control engineers and researchers working in the fields of active steering systems of vehicles, including commercial trucks.