Zbigniew Lozia

Uncertainty Study of Road Accident Reconstruction - Computational Methods

One purpose of accident reconstruction is to define the motion parameters of the participants before the accident. This paper examines some issues related to the assessment of computational accuracy concerning reconstruction of a vehicles motion from the threat occurrence until the accident or accident avoidance. The basic method of computation credibility assessment is experimental verification of models. In the case of errors resulting from inaccuracies of value assessments for parameters, there are several methods that allow for assessing an error in analysis. These methods include determined methods (e.g., total differential method and extreme values method) and probabilistic methods (e.g., Gauss method, methods with the use of stochastic processes, Monte Carlo method). These methods were compared on the basis of their application in the case of a braking process study of a vehicle in rectilinear motion. Also for the aforementioned case, the results obtained by means of various computational methods of vehicle motion (analytical and simulation models) were compared with the outcome of the experimental study. Findings indicate the failure to consider inaccuracies in data assessment may lead to a false hypothesis of the course for a given accident situation. However, the selection of the best method depends on the adopted model of the analyzed phenomenon and the possibility to define data. Limitations of each method should be considered when choosing a method.

ROLLOVER THRESHOLDS OF THE BIAXIAL TRUCK DURING MOTION ON AN EVEN ROAD.

Abstract The paper presents the results of analytical and simulation investigations on maximum possible truck velocity and lateral acceleration without rollover during curvilinear motion on an ideally smooth, horizontal, high friction road surface. Results of four different method were compared. 1st order sensitivity analysis was applied to investigate the influence of body CG height.

An analysis of vehicle behaviour during lane-change manoeuvre of an uneven road surface

SUMMARY The paper presents results of simulation investigations of biaxial vehicle motion on an even and uneven road during lane-change-type manoeuvre. Test conditions, method, data processing, analysis and presentation are according to ISO/TR 8725 [l]. The road surface irregularities adopted for the investigations correspond to two roads of different class according to ISO/TC 108/253 [2] and one ideal, even surface. Obtained results indicate that there is a considerable influence of road irregularities on vehicle behaviour during lane-change-type manoeuvre.

MODELLING AND SIMULATING THE BRAKING PROCESS OF AUTOMOTIVE VEHICLE ON UNEVEN SURFACE

SUMMARY This paper presents the mathematical model of a vehicle. The model has been used to describe the car braking process on an uneven rectilinear road. The model is built in such a way to allow applying interchangeably one of the six models of the tire radial properties in it - five of the models have been taken from the literary sources. Irregularities of the road surface are the realization of the random process which is desoribed by the power spectral density. Three-parametric description of the tire tangential properties has been applied here.Results obtained from the comparison of the six models of the tire radial properties as well as exemplary results obtained from the simulation of the oar braking process on even and uneven road surfaces have all been presented in this paper. An attempt has been undertaken to evaluate the influence of the road unevenness upon the effectiveness of the oar braking process.

A COMPARISON OF DRIVER STEERING ACTIVITY DURING MOTION ON AN EVEN AND UNEVEN ROAD SURFACE

SUMMARY The paper presents results of simulation investigation on driver-vehicle motion on an even and uneven road. The 14 degrees of freedom vehicle model has been verified experimentally on an even road surface. The driver models were adopted to perform typical motion cases: circular steady state and stright line. Road irregularities were realizations of a random process and they represented four road categories. The driver steering activity measure was adopted to investigate the influence of road undulations. The performed simulation investigations indicate that there is a considerable influence of road irregularities on the driver-vehicle system behaviour during two typical motion cases.

The use of a linear half-vehicle model for the optimization of damping in the passive suspension system of a railway car

The paper presents a methodology of optimizing the parameters of the passive suspension system of a railway vehicle. A linear half-vehicle model and an example of the procedure carried out to optimize a selected parameter of the model have been demonstrated. A method of the selection of damping in the suspension system of a railway vehicle, based on over 40-year achievements of the cited authors of publications in the field of motor vehicles, has been shown. The optimization of linear damping in the secondary suspension system of a passenger carriage moving on a track with random profile irregularities has been described in detail. The algorithms adopted for the calculations have a wider range of applicability; especially, they may be used for determining the optimum values of the other parameters of the railway vehicle model under analysis, i.e. stiffness of the secondary suspension system as well as stiffness and damping of the primary suspension system.

Biaxial Vehicle Motion Simulation and Animation

This paper presents two simulation models which describe the motion and dynamics of biaxial vehicles: a passenger car and 112 ton truck on even and uneven road surfaces. Based on simulation results, original graphical postprocessor presents animation of vehicle motion in assumed scenery including other vehicles. (A) For the covering abstract of the symposium see IRRD 882950.

A TWO-DIMENSIONAL MODEL OF THE INTERACTION BETWEEN A PNEUMATIC TIRE AND AN EVEN AND UNEVEN ROAD SURFACE

SUMMARY The paper presents a two-dimensional model of pneumatic tire interacting with even and uneven road surface. The model describes jointly radial and tangential tire properties, assuming variation of the friction coefficient at the contact points. Such a model can be useful in describing the interaction between the pneumatic tire and road, that is characterized by a relatively big value of the ratio of the road unevenness height to its length.

Heart rate variability (HRV) and muscular system activity (EMG) in cases of crash threat during simulated driving of a passenger car

ObjectivesThe aim of the study was to verify whether simultaneous responses from the muscular and circulatory system occur in the driver’s body under simulated conditions of a crash threat.Materials and MethodsThe study was carried out in a passenger car driving simulator. The crash was included in the driving test scenario developed in an urban setting. In the group of 22 young male subjects, two physiological signals — ECG and EMG were continuously recorded. The length of the RR interval in the ECG signal was assessed. A HRV analysis was performed in the time and frequency domains for 1-minute record segments at rest (seated position), during undisturbed driving as well as during and several minutes after the crash. For the left and right side muscles: m. trapezius (TR) and m. flexor digitorum superficialis (FDS), the EMG signal amplitude was determined. The percentage of maximal voluntary contraction (MVC) was compared during driving and during the crash.ResultsAs for the ECG signal, it was found that in most of the drivers changes occurred in the parameter values reflecting HRV in the time domain. Significant changes were noted in the mean length of RR intervals (mRR). As for the EMG signal, the changes in the amplitude concerned the signal recorded from the FDS muscle. The changes in ECG and EMG were simultaneous in half of the cases.ConclusionSuch parameters as mRR (ECG signal) and FDS-L amplitude (EMG signal) were the responses to accident risk. Under simulated conditions, responses from the circulatory and musculoskeletal systems are not always simultaneous. The results indicate that a more complete driver’s response to a crash in road traffic is obtained based on parallel recording of two physiological signals (ECG and EMG).