S. Caglar Baslamisli

Gain-scheduled integrated active steering and differential control for vehicle handling improvement

This paper presents a gain-scheduled active steering control and active differential design method to preserve vehicle stability in extreme handling situations. A new formulation of the bicycle model in which tyre slip angles, longitudinal slips and vehicle forward speed appear as varying vehicle parameters is introduced. Such a model happens to be useful in the design of vehicle dynamics controllers scheduled by vehicle parameters: after having expressed the parametric bicycle model in the parametric descriptor form, gain-scheduled active steering and differential controllers are designed to improve vehicle handling at ‘large’ driver-commanded steering angles. Simulations reveal the efficiency of the selected modelling and controller design methodology in enhancing vehicle handling capacity during cornering on roads with varying adhesion coefficient and under variable speed operation.

Design of a multiple-model switching controller for ABS braking dynamics

The purpose of this study is to design high-performance active braking control and observer algorithms for passenger vehicles equipped with electromechanical brake systems. These algorithms are designed to be adaptive with changing driving and road conditions in a switched multiple-model manner to ensure high performance and robustness. The effectiveness of a set of multiple-model switching lead-lag controllers is evaluated during transitions between different road friction coefficients. Meanwhile, a multiple-model switching observer algorithm is developed to estimate the shape of the tyre braking force curve with respect to the longitudinal slip. Each switched observer predicts signals according to its preset tyre model. The observers are designed based on different Burckhardt tyre models that are parameterized for different road conditions. In our simulations, the value of the friction coefficient is assumed to be unknown and our switching algorithms are observed to estimate successfully the varying friction coefficients by comparing a quadratic cost function of measured signals from the vehicle with signals generated by observers. We demonstrate that our algorithms provide high reliability and fast response, thus ensuring a stopping distance close to the theoretical minimum.

Optimization of Speed Control Hump Profiles

In this study, the goal attainment method is implemented for the optimization of speed control hump profiles. Basic dimensions for a number of hump profile functions are optimized for single vehicles classified in five categories and for a specified distribution of these vehicles. Objective functions are selected as combinations of the longitudinal and vertical acceleration components at pre-specified points on the vehicle body. The main objective is to minimize vehicle response functions below the hump crossing speed limit and to maximize them above the speed limit. Typical characteristics of a series of two axle vehicles, described by the half car model, are used and the performances of various hump profiles are assessed.

Application of the Operational Modal Analysis Using the Independent Component Analysis for a Quarter Car Vehicle Model

This paper investigates the dynamic behavior of a quarter car vehicle system using the Operational Modal Analysis (OMA) . This method is applied using one of the major techniques of the Blind Source Separation (BSS) which is the Independent Component Analysis (ICA) . Compared to the classical modal analysis, the Operational Modal Analysis presents the advantage that it is only based on the vibratory responses of the structure in order to identify its modal parameters. To validate this approach in the case of a quarter car vehicle model , the estimated results obtained by the OMA methods are presented and compared with those obtained by the modal recombination method.

Adap-tyre: DEKF filtering for vehicle state estimation based on tyre parameter adaptation

This paper presents an application of the dual extended Kalman filter (DEKF) algorithm for the estimation of vehicle/tyre dynamics states and parameters. The developed algorithm Adap-tyre relies on online adaptation of simple tyre models available in the literature and it is used in this paper for vehicle handling estimation. The performance of Adap-tyre is assessed by comparing estimated vehicle characteristics (vehicle body sideslip angle and tyre lateral forces) and tyre parameters with characteristics of a non-linear vehicle planar model with tyres modelled according to the magic formula. Simulation results indicate that the proposed algorithm is very efficient in estimating critical vehicle states and tyre parameters.

A new sliding-mode controller design methodology with derivative switching function for anti-lock brake system

In this study, anti-lock brake system control using sliding-mode controller is investigated. Different alternatives for the switching function and the sliding surface, involved in the structure of the sliding-mode controller, are explored. It was aimed to reach a better controller performance with less chattering and robustness to actuator imperfections. Regarding applicability, tire force response was modeled as a uniformly distributed uncertain parameter during controller designs. Controllers are simulated for both constant and varying coefficient of friction roads, with optimized design parameters. The effects of actuator first-order dynamics and transportation delay, which come up in practical implementations, were considered. The sliding-mode control structure which employs derivative switching function with integral sliding surface is originally proposed in this study. It is found to produce less chattering and provide more robustness, which could not be achieved side by side using former designs.

Road profile identification with an algebraic estimator

In order to isolate the propagation of unwanted vibrations to passengers and improve vehicle maneuverability, it is common practice to predict road profile roughness in the scope of active suspension design. An algebraic estimator designed for the estimation of the road profile excitation has been investigated in this study based on vehicle dynamics responses. An approximation of road profile excitation by a piecewise constant function has been proposed using the operational calculus method and the differential algebraic theory. The proposed technique allows for the usage of cheap instrumentation with a small number of sensors and employs a straightforward calibration process. Accurate approximation of the road profile was obtained from the measurement of sprung mass and unsprung mass vertical displacements. The performance and robustness of the proposed algebraic predictor is compared with an augmented Kalman estimator. Numerical results are provided to analyze the effectiveness and the limitations of the proposed algorithm for road profile reconstruction. Furthermore, a comparison with real profile was studied.

Operational Modal Analysis for a Half Vehicle Model

The objective of this paper is to use the Independent Component Analysis technique (ICA) in the Operational Modal Analysis (OMA) in order to determine the modal parameters of a half car model with four degrees of freedom. The ICA method is a major technique of the Blind Source Separation (It considers the studied system as a black box and knowing only its responses it can estimate its modal parameters) which is based on the inverse problem. In our case, this technique can be used to reconstruct the modal responses of the half car model knowing only its vibratory responses. In this paper, these vibratory responses are numerically computed using the Newmark approach and they constitute the observed signals for the ICA algorithm. So that based only on the knowledge of these responses, the ICA estimates the modal characteristics (modal responses, eigenfrequencies) of the studied half car model. Finally, the modal responses of the studied system obtained by the classical modal analysis are compared with those estimated by the ICA technique using some performance criteria which are the Modal Assurance Criterion (MAC number) and the relative error. The obtained results show a good agreement between the theoretical and estimated modal characteristics.

Estimation of Road Disturbance for a Non Linear Half Car Model Using the Independent Component Analysis

The identification of the road profile disturbance acting on a vehicle was the objective of many recent researches. This estimation remains very interesting since it contributes to study the dynamic behavior of the vehicle in one side and to choose a control law later in other side. However most of the used techniques have many drawbacks such us those based on direct measurements of the profile which need costly profilometers or those based on neural network algorithm which are very complicated. So the purpose of this research is to use a new method named the Independent Component Analysis (ICA) to estimate the road profile. This method is based on the so-called inverse problem. So it necessitates only the knowledge of the dynamic responses of the vehicle to identify the road disturbance. Therefore the Newmark algorithm is used in this paper to extract the dynamic responses of the system under study which is a non linear half car model. Starting from these responses, the ICA algorithm is applied. The validation of the obtained results is done using some performance criteria which are the relative error and the MAC number. Finally a good agreement is found between the original profile and the estimated one.

On-line Adaptive Scaling Parameter in Active Disturbance Rejection Controller

Active Disturbance Rejection Controller (ADRC) is considered one of the most famous model free controllers in the industry. This introduced scheme of control, do not require the exact modeling of the system equations and used to reject online any types of perturbations. However, the drawback of this tool is the hard task of tuning multi-parameters and takes a long time to achieve performances requirements. In this contribution, an optimization of a scaling parameter which has an important effect in the dynamic behavior of controlled system. There has been some research concentrate in estimate the parameters uncertainties from input and output signals of the body mass in vehicle system. This kind of estimation is based on differential algebra which is known by its simplicity of implementation, fast and robust to noise marring any measured signals. Furthermore, the combination of this algebraic methodology with aforementioned control low is easy. For the purpose of improving the effectiveness of ADRC controller, this paper use to predict this unknown variation and it was incorporated in the equation of control. Using this time varying parameter instead of an empirical one, simulations results show an amelioration of the energy consumption and an increase of the ride comfort.