László Palkovics

Intelligent Electronic Systems in Commercial Vehicles for Enhanced Traffic Safety

Looking at the future trends of the road traffic, one will recognize that the commercial vehicle participation will not decrease, although it is required from the environmental and social viewpoints. The reason is that the other means of freight transport (water, railway, air) do not provide the same flexibility as the road transport, and direct business interest of those companies, who are using this transport form is larger than the eventual loss caused by the penalties to be paid (taxes, compensation of higher axle load). This conflict is hard to solve, but the effect can be minimized. The commercial vehicle industry attempts to introduce systems to the vehicles, which are targeting on reduction of the environmental impacts caused by heavy vehicles. These systems, which are named generally as “intelligent chassis systems”, electronically control the operation of the chassis subsystems (engine, transmission, brake, suspension) and co-ordinate their operation on a higher level (vehicle controller, intelligent control systems, such as adaptive cruise control, video camera based lane change recognition system, etc.). This paper reviews the state-of-the-art of the commercial vehicle chassis systems, and tries to project their future development.

Design of Active Suspension System in the Presence of Physical Parametric Uncertainties

The purpose of the paper is to study the design of the active wheel suspension system. The goal of the control design is the disturbance attenuation with respect to the road disturbances when some of the physical parameters of the system are uncertain. On the basis of a linear quarter-car model the tire stiffness and suspension stiffness are assummed to be uncertain. In this paper the authors deal with some new robust design methods. They examine the applicability of H¿ control in case of the active suspension system using a quarter-car model. The problem is solved as a direct state-feedback H¿ control problem and in case of structured uncertainties as an RLQR (Robust LQR) design task. On the basis of combination of these two methods new procedure is proposed.

Effect of the Controller Parameters on the Steerability of the Four Wheel Steered Car

SUMMARY The four-wheel-steering systems of the cars are becoming more and more wide-spread. In addition to the conventional 4WS systems (e.g. the steering-wheel-angle dependent four-wheel-steering and the speed dependent 4WS) there already exist some so called active 4WS systems. The front wheels and rear wheels are steered autonomously by the feedback compensation and in this manner the behaviour of the car during high-speed turning manoeuvre and under the side wind gust is improved. But what happens if some of the parameters of the car are changed? In the present paper, the author will analyze the systems response when the internal tyre pressure in the rear wheels is lower than the normal. Due to this the under-steered car becomes over-steered and the question is whether the control system is able to stabilize the motion of the vehicle.

Modelling and Simulating of Self-Energizing Brake System

Using the very old idea, the wedge, there is a good opportunity to realize the self-amplified system. The basic idea is that the rotation energy of the brake disc can be used as an actuation source for the brake system. In this way, the additional actuation force comes with the intervention of friction. The value of the friction coefficient varies in a very wide range, and its effect is very important from the viewpoint of the control algorithm. The system can come to the instable state easier if the coefficient of friction–wedge angle pairs produce self-locking state. In order to analyse the behaviour of this self-energizing brake system, a mechanical model has been created including the accurate description of friction characteristics. This paper focuses on the modelling steps of the self-energizing wedge brake. A complete parameter analysis will be demonstrated in order to understand the model. The stability conditions of the model will be analysed.

Design of an active 4ws system with physical uncertainties

Abstract In this paper a new approach to the design of an active four-wheel-steered (4WS) control system is introduced. The problems of the conventionally used LQ-controller-based virtual model following control strategies are analyzed, and several problems are addressed. Two main problems of the LQ controller are highlighted: the external disturbance rejection, and the robustness of the controlled system in the face of parametric uncertainties. In the paper a combined Robust Linear Quadratic Regulator (RLQR) and H∞ controller design is presented for an active WS vehicle. The applicability of this kind of controllers is proven in this particular design case.

Analysis and experimental verification of faulty network modes in an autonomous vehicle string

Advanced autonomous vehicle strings rely on inter-vehicle communication in order to decrease the necessary safety gap so that fuel consumption can be decreased and road capacity can be increased. In case of failures of some communication channels, the corresponding back-up control strategy must be switched on. Maximal spacing errors of such back-up modes are analyzed and compared. Robustness to platoon heterogeneity and communication delays are considered. The main conclusion we can draw is that, in the full communication mode, satisfactory spacing performance can be achieved by using simple output-feedback controllers designed without detailed knowledge on engine/brake characteristics, only utilizing the existing services available today in every commercial heavy trucks with automatic gearbox. Experimental verification of the designed controllers are presented.

Guaranteed peaks of spacing errors in an experimental vehicle string

Abstract Controllers for autonomous vehicle strings usually consist of local feedback controllers responsible for performing acceleration demands and a common control law aimed at the string stability of the entire platoon. Based on analysis of robust peak-to-peak performance and experimental verification, it is shown in the paper that satisfactory spacing performance can be achieved without accurate knowledge on the engine/brake/gear systems, only by using a common control law that relies on inter-vehicle communication and the commercial on-board services of todays heavy vehicles.

Automatic Detection of the Lane Departure of Vehicles

The paper reports on the development of an experimental warning system for the visual detection of the unintentional lane departure of road vehicles. The hardware system assembled from available low-cost parts and a fundamental adaptive algorithm are described. The system has been placed on a test vehicle and tested on motorways in real situations by daylight and by night. The results are illustrated with pictures selected from the records saved during the experiments.

Visual lane and obstruction detection system for commercial vehicles

Abstract This paper presents the development of an experimental system for the visual detection of unintended lane-departures of commercial road vehicles. If such event is detected, a warning signal is sent to the driver and a message to the supervisor system. The supervisor can intervene in the motion of the vehicle while it monitors the driver’s activity and the status of the drive stability control system. The edge detection algorithms, which are used to recognize lane geometry, and which are the basis of lane-departure detection, are summarized. The paper presents another experiment in the detection of a three-dimensional object, i.e. an obstruction, in the lane ahead of the vehicles in order to prevent too short safety gaps. The distance can be estimated by processing the stereo images of two cameras.

Comparison of control strategies in case of commercial vehicle's active steering

It is a timeless and actual problem to develop vehicles active safety [1]. In case of commercial vehicle category more sophisticated difficulties could be found. Increased mass and inertia are the fundamental differences between a usual passenger car and a truck. At the same time, the low series number requests cheap solutions. The aim is in this way to ensure low cost solutions to control increased kinetic energies.