Posūkio trajektorija slydimo režimu judančio automobilio dinaminių parametrų tyrimas

Disertacijoje nagrinėjamas posūkio trajektorija judančio automobilio dina-minių parametrų ryšys su padangų slydimo pėdsakų parametrais. Tiriant eismo įvykius pradinis posūkyje išslydusio automobilio greitis nustatomas pagal padangų pėdsakų trajektorijos spindulį, kurio reikšmė labai priklauso nuo tiesiogiai matuojamų pėdsako parametrų. Darbe slydimo režimu judančio automobilio tyrimams naudojama sukurta slydimo sistema, o tiksliam padangų pėdsako trajektorijos nustatymui pritaikoma fotogrametrijos principais pagrįsta metodika. Disertaciją sudaro įvadas, keturi skyriai, bendrosios išvados, naudotos literatūros ir autoriaus publikacijų disertacijos tema sąrašai bei šeši priedai. Įvadinėje dalyje įvardijama tiriamoji problema ir darbo aktualumas. Aprašomas tyrimų objektas, tikslas ir suformuluojami darbo uždaviniai, aprašoma tyrimų metodika, darbo mokslinis naujumas, rezultatų praktinė reikšmė ir ginamieji teiginiai. Įvado pabaigoje pristatomos disertacijos tema autoriaus paskelbtos publikacijos, pranešimai mokslinėse konferencijose ir seminaruose bei disertacijos struktūra. Pirmajame skyriuje apžvelgiama mokslinė literatūra disertacijos tema. Pateikiama posūkio trajektorija judančio automobilio svarbiausių parametrų ir kritinių stabilumo rodiklių analizė. Apžvelgiama simuliatorių taikymo tyrimuose tendencija ir padangų slydimo pėdsakų tyrimai. Antrajame skyriuje pristatoma sukurta automobilio slydimo sistema ir sudarytas 22 laisvės laipsnių matematinis modelis. Trečiajame skyriuje pateikiama eksperimentinių tyrimų metodika ir naudojama įranga. Slydimo sistemos įtaka įvertinama pastovaus posūkio manevru gaunamomis automobilio dinaminėmis charakteristikomis. Šiame skyriuje sudaromas automobilio kritinio greičio nustatymo algoritmas ir padangos slydimo pėdsako trajektorijos atkūrimo pritaikytais fotogrametrijos principais metodika. Ketvirtajame skyriuje analizuojami eksperimentinių tyrimų ir matematinio modeliavimo rezultatai, pagal juos sudaromos automobilio trajektoriją apibūdinančių parametrų ir greičio ryšio priklausomybės. Disertacijos tema paskelbta 12 mokslinių straipsnių: trys – mokslo žurnaluose, įtrauktuose į Thomson ISI sąrašą; devyni – kituose recenzuojamuose žurnaluose. Disertacijos tema skaityti devyni pranešimai mokslinėse konferencijose Lietuvoje ir penki – mokslinėse konferencijose bei seminaruose užsienyje

A Method for Automatic Image Rectification and Stitching for Vehicle Yaw Marks Trajectory Estimation

The aim of this study has been to propose a new method for automatic rectification and stitching of the images taken on the accident site. The proposed method does not require any measurements to be performed on the accident site and thus it is frsjebalaee of measurement errors. The experimental investigation was performed in order to compare the vehicle trajectory estimation according to the yaw marks in the stitched image and the trajectory, reconstructed using the GPS data. The overall mean error of the trajectory reconstruction, produced by the method proposed in this paper was 0.086 m. It was only 0.18% comparing to the whole trajectory length.</p

Vehicle Velocity Relation to Slipping Trajectory Change: An Option for Traffic Accident Reconstruction

In this paper, the relation of the velocity of a vehicle in the slip mode to the parameters of the tire marks on the road surface is examined. During traffic accident reconstructions, the initial velocity of a sideslipping vehicle is established according to the tire mark trajectory radius, and calculations highly depend on the directly measured parameters of the tire marks, in particular cases known as yaw marks. In this work, a developed and experimentally validated 14-degree-of-freedom mathematical model of a vehicle is used for an investigation of the relation between velocity and trajectories. The dependence of initial vehicle velocity on tire yaw mark length and trajectory radius was found as a characteristic relation. Hence, after approximation of the permanent slipping part by a polynomial, the parameters of the latter were related to vehicle velocity. The dependences were established by specific experimental tests and computer-aided simulation of the developed model

Prediction of Road Accident Risk for Vehicle Fleet Based on Statistically Processed Tire Wear Model

The goal of the paper is to investigate the impact of tire tread depth on road accident risk and to develop an accident rate prediction model. The state of 4288 vehicle tires using tread depth gauge was inspected and processed statistically. The tread depth of the most worn tire from each vehicle was registered for further analysis. Based on the collected data, a statistical tire tread depth model for an insurance company vehicle fleet had been developed. The conformity of the gamma distribution to the data was verified upon applying the Pearson compatibility criterion. The paper provides the histograms of the frequencies of tire tread depths and the theoretical curves of the distribution density. The probability of the accident risk depending on the tire tread depth (adaptive risk index) was calculated applying the formed distributions and risk index dependence on the tire tread depth for the inspected vehicle fleet. According to the developed prediction model, an upgrade of the regulation for the minimum allowed tire tread depth by 2 mm (up to 3.6 mm) could reduce road accident risk (caused by poor adhesion to road surface) to 19.3% for the chosen vehicle fleet. Such models are useful for road safety experts, insurance companies and accident cost evaluation specialists by predicting expenses related to insurance events

Influence of VANET System on Movement of Traffic Flows in Emergency Situations

The paper presents Vehicular Ad Hoc Network (VANET) system based on an analysis of the movement of a motorcade in an emergency situation. This analysis seeks to answer the question: when and under what conditions Emergency Message (EM) sent by Vehicle-to-Vehicle (V2V) system reaches the final target to help in preventing of serious accidents, such as multi-vehicle collisions. The model of calculation based on the key principles of vehicle braking enables finding the time to possible collision and the residual velocity of the vehicle. In the calculations, the average values of the driver’s reaction time are accepted; in addition, a sent emergency message is considered to be free of interference. Upon choosing different road and driving conditions, it is found what vehicle of the motorcade stops before the possible obstacle on emergency braking. The performance of vehicles with and without VANET system is compared. </p

The impact of road roughness on the duration of contact between a vehicle wheel and road surface

The paper analyses the impact of the road micro-profile on the duration and the type of the vehicle wheel contact with the road surface driving at different speed. The selected vehicle bicycle model describes vertical displacements of front and rear wheels and their suspension as well as the impact of the vehicle body motion and longitudinal oscillation. International Roughness Index (IRI) and micro-profile irregularities of the road section analysed in the paper were identified using specialized road testing equipment. The experimental investigations measuring the vehicle suspension displacement and the body acceleration were carried out. Frequency characteristics of suspension motion and regularities of vertical movement of the wheel were identified after dividing the investigated road section according to driving modes. The analysis into the wheel contact with the road surface and identified correlations enable to determine the vehicle stability on selected quality roads

Variability of gravel pavement roughness: an analysis of the impact on vehicle dynamic response and driving comfort

Gravel pavement has lower construction costs but poorer performance than asphalt surfaces on roads. It also emits dust and deforms under the impact of vehicle loads and ambient air factors; the resulting ripples and ruts constantly deepen, and therefore increase vehicle vibrations and fuel consumption, and reduce safe driving speed and comfort. In this study, existing pavement quality evaluation indexes are analysed, and a methodology for adapting them for roads with gravel pavement is proposed. We report the measured wave depth and length of gravel pavement profile using the straightedge method on a 160 m long road section at three stages of road utilization. The measured pavement elevation was processed according to ISO 8608, and the frequency response of a vehicle was investigated using simulations in MATLAB/Simulink. The international roughness index (IRI) analysis showed that a speed of 30-45 km/h instead of 80 km/h provided the objective results of the IRI calculation on the flexible pavement due to the decreasing velocity of a vehicle’s unsprung mass on a more deteriorated road pavement state. The influence of the corrugation phenomenon of gravel pavement was explored, identifying specific driving safety and comfort cases. Finally, an increase in the dynamic load coefficient (DLC) at a low speed of 30 km/h on the most deteriorated pavement and a high speed of 90 km/h on the middle-quality pavement demonstrated the demand for timely gravel pavement maintenance and the complicated prediction of a safe driving speed for drivers. The main relevant objectives of this study are the adaptation of a road roughness indicator to gravel pavement, including the evaluation of vehicle dynamic responses at different speeds and pavement deterioration states

Technological measures of forefront road identification for vehicle comfort and safety improvement

This paper presents the technological measures currently being developed at institutes and vehicle research centres dealing with forefront road identification. In this case, road identification corresponds with the surface irregularities and road surface type, which are evaluated by laser scanning and image analysis. Real-time adaptation, adaptation in advance and system external informing are stated as sequential generations of vehicle suspension and active braking systems where road identification is significantly important. Active and semi-active suspensions with their adaptation technologies for comfort and road holding characteristics are analysed. Also, an active braking system such as Anti-lock Braking System (ABS) and Autonomous Emergency Braking (AEB) have been considered as very sensitive to the road friction state. Artificial intelligence methods of deep learning have been presented as a promising image analysis method for classification of 12 different road surface types. Concluding the achieved benefit of road identification for traffic safety improvement is presented with reference to analysed research reports and assumptions made after the initial evaluation

MODELLING AND VALIDATION OF A TESTING TRAILER FOR ABS AND TYRE INTERACTION ON ROUGH TERRAIN

The main purpose of a vehicle anti-lock braking system (ABS) is to prevent the tyres from locking-up in order to brake efficiently whilst maintaining steering control and stability. Sport utility vehicles (SUV) are designed to drive on various roads under different driving conditions, making it challenging to identify optimal operating conditions for ABS algorithms to be implemented. This paper describes the development and modelling of a testing trailer that is designed to benefit the research of a SUV tyre operating in ABS braking modes on non-deformable rough terrain. The test trailer can be to investigate the variation of tyre contact forces and vibration characteristics influenced by ABS braking and rough terrain excitation. Undesirable fluctuations of wheel speed, normal force and braking moments make measurements more complicated and limits the performance of active safety systems. A trailer made from a Land Rover Defender chassis is used with standard ABS components and is implemented with a Bosch ABS algorithm for experimental tests. In addition to the ABS system the necessary measuring equipment such as Wheel Force Transducers (WFT), accelerometers, brake pressure transducers, GPS and vehicle speed measurement instrumentation is used. An Adams model of the trailer in co-simulation with ABS and test control in MATLAB/Simulink is created to validate the model. The centre of gravity position and inertia characteristics of the trailer are determined through experimental testing. A validated FTire tyre model, suitable for off-road conditions, is incorporated to accurately resemble the specific tyre used during tests. The validated Adams model and test trailer will enable further development of ABS algorithms including the identification of key parameters through which ABS braking can be optimised for various roads as well as optimizing interaction with semi-active suspension systems

THE MEDIATING ROLE OF PERSONALITY IN THE RELATIONSHIP BETWEEN REACTION TIME AND TRAFFIC PERCEPTION IN YOUNG ADULTS

The objective of this research was to examine how personality acts as a mediator in the relationship between reaction time and traffic perception in young adults. Given the increase in the number of road accidents among this age group in the European Union, it is essential to understand the psychological determinants of risky driving behavior. A sample of 60 participants from Poland, Slovakia, and Lithuania was assessed using the Vienna Test System to measure personality, reaction time, time-movement anticipation, and traffic perceptions. The results indicate gender differences in self-control personality factor and motor reaction time, as well as a positive correlation between the sense of responsibility and time-movement anticipation. The proposed model was confirmed, demonstrating that mental stability mediates the relationship between reaction time and traffic perceptions. A driver with high mental stability can react faster to stimuli while accurately perceiving objects in road traffic. This study has implications for road safety policies and practices. Incorporating personality assessments into driver training programs can help develop interventions that target specific personality traits. Furthermore, interventions aimed at enhancing mental stability may help reduce the likelihood of accidents among young drivers. However, this study’s limitations, such as the small sample size and narrow age range, should be considered in future research with other age groups and additional variables that directly impact traffic safety