Lateral Acceleration Research Articles

Effects of Road Marking Visibility on Vehicles Driving Along Curves: A Preliminary Study in a Simulated Environment

The role of road markings is fundamental for traffic safety, as it represents an essential optical driving instrument both for effective drivers and autonomous vehicles. This research aims to evaluate the effects of the decay of road marking visibility along curves, specifically the variability in lateral acceleration. Traditionally, issues related to the correct interpretation of a road alignment were studied by means of trajectory analyses. However, they involved information about the vehicle’s geometrical position without any indication on dynamics. To explore this aspect further, an experiment in a simulated environment involving 21 drivers was performed. They drove along a test road in a standardized scenario considering only three variables: the curve direction (right or left), the deviation angle (70° or 30°), and the road marking visibility percentage (100%, 50%, 10%, and 0%). The results, in differences between theoretical (depending on design speed and curve radius) and effective lateral accelerations, provide further evidence of the strategic role of the markings. However, when markings deteriorate, drivers activate some balancing mechanisms to mitigate the dynamic effects along curves and, in turn, to improve comfort and safety. The proposed procedure is not only of direct practical interest, but it is also fully generalizable to other contexts and issues, involving several other elements that may influence the phenomenon, such as road geometry, visibility conditions, and traffic flow speed.

An interval-based multi-objective robust design optimization for vehicle dynamics

This study presents an Interval-based Multi-objective Robust Design Optimization (IB-MORDO) algorithm applied to a vehicle dynamic problem. The proposed algorithm optimizes a full 15 degrees-of-freedom (15-DOF) vehicle model, subjected to a double-lane change (DLC) maneuver under random road profiles, to attain driver comfort and safety. This study does not make assumptions about uncertain parameter statistics; instead, the uncertainties are quantified using a non-probabilistic α-cut level interval analysis. These uncertainties are applied to the system parameters and design variables to ensure robust results. After the optimization process, the root mean square (RMS) vertical acceleration at the driver’s seat resulted in a robust solution of 1.041 m/s2 and a parameter interval radius (IR) equals to 0.631 m/s2, whereas the RMS lateral acceleration at the driver’s seat resulted in a solution of 1.908 m/s2 with an interval radius of 0.168 m/s2. Unlike the Robust Optimization, the algorithm proposed herein considers uncertainties at system parameters and design variables without assuming any statistical data. HIGHLIGHTS An Interval-based Robust Multi-objective Optimization procedure is proposed and tested on a 15-DOF vehicle model. Αn α-cut level methodology is used to deal with the uncertainty propagation. Resulted optimal suspension parameters minimize center and interval radius of driver’s vertical and lateral accelerations.

Path tracking and stability integrated control of intelligent vehicles under steering collision avoidance

In order to improve the path tracking performance and stability of intelligent vehicles during steering and collision avoidance working condition, an integrated control method combining four-wheel steering, active suspension and direct yaw-moment is proposed. Firstly, a unified chassis dynamics model with 18 degrees-of-freedom (DOF) is established, which includes steering, braking and suspension subsystems. Phase plane analysis results for both traditional 2-DOF bicycle model and the 18-DOF model are compared. The results show that although the uneven road has a certain influence on the phase portraits of sideslip angle and sideslip angular velocity of the 18-DOF model, the overall trend is consistent with those of the 2-DOF model. Secondly, a general control framework for steering and collision avoidance of autonomous vehicle is put forward, consisting of the steering control for path tracking, and active suspension and direct yaw-moment control for stability. The collision avoidance reference path is planned by the fifth-degree polynomial, and three types of steering control methods including optimal control front wheel steering, optimal control four-wheel steering and front wheel steering combined with feedforward and feedback control, are adopted for comparison. The main contribution of this paper is that the role of active suspension is considered in the path tracking and stability integrated control of intelligent vehicles under steering collision avoidance. The active suspension subsystem uses optimal control method by two different kinds of weight coefficients, which can be switched between “comfort mode” and “sport mode” based on the vehicle lateral acceleration. According to the phase portraits of vehicle center of gravity sideslip angle and sideslip angular velocity, the direct-yaw moment control system adopts proportional differential control method based on the distance from the state point to the stability boundary. Finally, simulations and comparative analysis are compared among four different control systems on high and low adhesion roads. The research results indicate that the integrated control system can improve the vehicle path tracking performance and stability significantly.

Exploring behavioral validity of driving simulator under time pressure driving conditions of professional drivers

Driving simulators have become an important tool in human factors research, given that they are appropriately validated. Therefore, this study aims to explore the behavioral (absolute and relative) validity of a fixed-base driving simulator by analyzing different driving behavior measures such as speed, longitudinal acceleration, lateral acceleration, and brake pedal force. Thirty professional drivers participated in the experiment and the data was collected in real and simulated worlds under No Time Pressure (NTP) and Time Pressure (TP) driving conditions. Initially, comparative analyses were conducted on different driving behavior measures using Wilcoxon-signed rank test to examine absolute validity of the driving simulator. Finally, Generalized Linear Mixed (GLM) models were developed for computing the effective distance between real and simulated worlds by quantifying the parameters and for establishing relative validity. In general, the continuous profiles of driving behavior measures followed similar trends in real and simulated worlds and comparative analyses indicated relative validity of the driving simulator. The GLM models showed significant interaction effect of driving environments (real-world and simulated world) and driving conditions (NTP and TP) where high driving speed, high brake pedal force, and low lateral acceleration were observed in simulated world under TP driving condition than real-world under TP driving condition. Overall, the statistical analyses showed qualitative correspondence (relative validity) of the driving behavior measures in between real and simulated worlds. The findings from the current study showed expediency of the driving simulator and its effectiveness in conducting research on human factors and driver safety.

In-field dynamic response of instrumented wine tanks subjected to aftershock earthquakes

An experimental investigation of the dynamic behaviour of anchored flat-based wine storage tanks in a winery located in Marlborough, New Zealand is presented herein. Six wine storage tanks with different dimensions, capacities, and anchorage systems were instrumented with accelerometers for approximately six weeks following the 2016 Kaikōura earthquake, providing an opportunity to conduct a parametric study of their dynamic response when subjected to 37 aftershock earthquakes. The largest accelerations measured in the horizontal (X and Y) and vertical (Z) axes directions at the top of the six tanks occurred in conjunction with a Mw5.48 aftershock earthquake, with analysis indicating that the peak acceleration at the tank top occurred along the horizontal (Y) axis with a value of 0.545 g.Analysis of accelerations recorded at the top of the six tanks revealed that for low-intensity earthquake shaking the largest accelerations were measured at the top of the 40kL tank. A comparison of the tank instrumentation data indicated that the 175kL tank with a shear bolt anchorage system performed better than the nominally identical 175kL tank with a necked tension anchorage system, with the maximum lateral accelerations attained in the horizontal X and Y axes directions for the tank with the necked tension anchorage system being on average 1.59 times and 1.39 times the acceleration attained for the tank with the shear bolt anchorage system. Analysis of the results for the highest intensity earthquake shaking (Mw5.48) also indicated that the two tanks with installed energy dissipation systems sustained less acceleration when compared to tanks with a traditional anchorage system. Also, good agreement was observed between the values of the impulsive period attained from the analysis of the tank instrumentation data and from finite element (FE) modal analysis.

Three-dimensional continuous-time integrated guidance and control design using model predictive control

In this study, a novel three-dimensional continuous-time integrated guidance and control (IGC) scheme is presented. The proposed method is developed on the basis of generalized model predictive control (GMPC) approach and super-twisting extended state observer (STESO). The GMPC is used to generate the optimal closed form control law for the interceptor and the STESO is applied to estimate the maneuvering target lateral accelerations as well as the lumped disturbances. To the aim of IGC design, a six-degrees-of-freedom model based on the interceptor-target kinematics and interceptor dynamics is constructed. Afterward, the GMPC control law formulation for a nonlinear system exposed to disturbances is extracted. Finally, the effectiveness of the proposed IGC system is studied by numerical simulations. The simulation results reveal satisfactory interception performance including less energy consumption in comparison to a recently proposed successful IGC method.

Influence of drill-string lateral collision on wellbore stability of a horizontal well

A finite element model of wellbore stability was proposed for a horizontal well, and drill-string friction and lateral collision in the process of rotary motion were taken into account. An unconfined compression test was used for model validation, the normalized yielded zone area (NYZA) was employed to analyze wellbore stability, and the influence of a lateral collision on wellbore stability was simulated. The results indicated that the stress-strain curve of numerical simulation consists with unconfined compression test, and the maximum relative error is <2.2%. The evolution of NYZA can be divided into three typical stages: stage I (static balance), stage II (dynamic growth), and stage III (dynamic balance). Both normal and shear stresses reach to the peak value in stage II, while they always fluctuate in a relatively small range in stage III, so that the wellbore stability mainly affected by the first collision of drill-string. Both lateral acceleration and friction effects have significant impact on wellbore stability. The initial collision position and the size of drilling tool have a certain influence on wellbore stability, while the revolving speed of drill-string almost has no impact. The present paper has guiding significance for wellbore collapse prevention and drilling parameter optimization.

Nonlinear rendezvous guidance law design for a receiver UAV based on the Lyapunov stability theory

The rendezvous problem in the autonomous aerial refueling (AAR) was researched for the receiver unmanned aerial vehicle (UAV). The three-dimensional guidance model was constructed for the UAV to pursue the virtual tanker. In order to guarantee the zero miss distance and the intercept angle constraints, a nonlinear rendezvous guidance law was designed for the UAV based on the Lyapunov stability theory. The guidance law generated the normal acceleration command and the lateral acceleration command. The velocity control system was designed by the sliding mode control method. It controled the UAV’s velocity to equal to that of the virtual tanker at the end of the rendezvous phase. The simulation results validate the effectiveness of the designed nonlinear guidance law and the velocity control system.

Design of Distributed Drive Control Strategy for Wheel Side Rear Drive Electric Bus Based on Neural Network Algorithm.

The electric bus driven by the wheel-side motor has a natural advantage for the driving stability control of the vehicle because the torque of each driving wheel is independently controllable. Based on the advantages of the artificial neural network control algorithm, this paper designs a direct yaw torque control strategy based on neural network PID control, and combines the steering characteristics of the vehicle to distribute the driving torque. The co-simulation results of Matlab/Simulink and TruckSim show that the designed control strategy can effectively reduce the vehicle’s center of mass slip angle and lateral acceleration under medium and high speed conditions, and ensure the stable driving of the bus.

Three-dimensional nonsingular impact angle guidance strategy with physical constraints

In this study, two nonsingular three-dimensional (3D) guidance strategies to intercept a stationary target with desired impact angles, subject to nonlinear coupled dynamics, field-of-view (FOV) limit and lateral acceleration bounds, are investigated. As a stepping stone, two novel sliding mode surfaces are designed, the convergence and boundedness of the two sliding mode surfaces can guarantee the impact-angle-constrained interception while maintaining the seeker’s lock-on condition during the guidance. A novel auxiliary system is also presented to compensate for the effects caused by input saturation. In addition, the analytical achievable impact angles set is presented in terms of the initial engagement condition. Numerical simulations with various constraints, a realistic missile model and comparison study have been considered to show the feasibility and effectiveness of the proposed strategies.

Physical Fitness and Upper Limb Asymmetry in Young Padel Players: Differences between Genders and Categories.

This study aimed to assess the physical fitness and upper body asymmetries of young padel players aged between 13 and 16 years and to determine the possible differences between genders and categories. A total of 60 padel players were divided into four groups: under-14 male (n = 15; age: 13.75 ± 0.45 years; height: 1.64 ± 0.07 m; weight: 54.7 ± 8.3 kg), under-14 female (n = 15; age: 13.75 ± 0.44 years; height: 1.60 ± 0.05 m; weight: 51.5 ± 6.0 kg), under-16 male (n = 15; age: 15.44 ± 0.51 years; height:1.71 ± 0.04 m; weight: 63.88 ± 6.2 kg) and under-16 female (n = 15; age:15.46 ± 0.52 years; height:1.63 ± 0.05 m; weight: 55.08 ± 3.6 kg). Handgrip strength, ischiosural flexibility, gestural speed of the dominant arm, vertical jump, cardiorespiratory capacity, lateral movement, lateral acceleration and reaction time were measured. Male players showed better results in manual grip strength, vertical jump power, cardiorespiratory capacity and lateral movement (p < 0.05). Moreover, males presented a higher percentage of asymmetry in upper limb strength. Female players showed better reaction time and greater flexibility (p < 0.05). Regarding the differences between categories, the under-16 players showed greater flexibility, gestural speed, vertical jump power, cardiorespiratory capacity and lateral movement compared to the under-14 players. These results can be used as reference values for coaches/physical trainers of younger categories to improve health control and physical performance planning.

Unified Model of Disturbances Acting Upon Gimbal Seeker in Anti-Tank Guided Missile

Optimisation of the dynamic response of gimbal seeker plays key role from the point of view of development of anti-tank guided missile’s systems. In this study the set of the most important internal disturbances were integrated in generalized model of two axis gimbal seeker implemented in MathWorks’ Simulink environment. Compared to previous works on the subject, it was enhanced by replacing simple friction model with dynamic LuGre friction. Furthermore, its Coulomb component was linked to the normal force induced by missile’s lateral acceleration. Control system of gimbal seeker proposed in paper was tuned with modelled disturbances turned off and then examined with them being turned one by one. System’s responses were assessed to be significantly deteriorated, proving need of disturbance modelling and its use in control systems’ design.

The coupled vibration of train and bridge as high-speed trains meet in crosswind

PurposeThis paper aims to study the influence of aerodynamics force of trains passing each other on the dynamic response of vehicle bridge coupling system based on numerical simulation and multi-body dynamics and put forward the speed threshold for safe running of train under different crosswind speeds.Design/methodology/approachThe computational fluid dynamics method is adopted to simulate the aerodynamic force in the whole process of train passing each other by using dynamic grid technology. The dynamic model of vehicle-bridge coupling system is established considering the effects of aerodynamic force of train passing each other under crosswind, the dynamic response of train intersection on the bridge under crosswind is computed and the running safety of the train is evaluated.FindingsThe aerodynamic force of trains' intersection has little effects on the derailment factor, lateral wheel-rail force and vertical acceleration of train, but it increases the offload factor of train and significantly increases the lateral acceleration of train. The crosswind has a significant effect on increasing the derailment factor, lateral wheel-rail force and offload factor of train. The offload factor of train is the key factor to control the threshold of train speed. The impact of the aerodynamic force of trains' intersection on running safety cannot be ignored. When the extreme values of crosswind wind speed are 15 m·s−1, 20 m·s−1 and 25 m·s−1, respectively, the corresponding speed thresholds for safe running of train are 350 km·h−1, 275 km·h−1 and 200 km·h−1, respectively.Originality/valueThe research can provide a more precise numerical method to study the running safety of high-speed trains under the aerodynamic effect of trains passing each other on bridge in crosswind.

Integrated impact time guidance and control against non-maneuvering targets

This paper proposes integrated guidance and control for skid-to-turn cruciform canard-controlled interceptors for controlling impact time along with interception of non-maneuvering targets. This approach circumvents the possible difficulties associated with designing guidance and control subsystems independently. An interceptor control surface deflection for achieving appropriate lateral acceleration to achieve the guidance objectives are derived using sliding-mode control considering nonlinear engagement dynamics, thereby remaining effective even for engagement with large initial heading errors. The switching surface is chosen to be a function of time-to-go and its rate with different time-to-go estimates against stationary and moving targets. The time-to-go estimate for stationary target accounts for the heading angle errors, while that for constant velocity target provides an exact value. Unlike many of the existing strategies, the proposed approaches enable the interceptor to achieve an impact time, even less than its initial estimates. The efficacy of the proposed guidance strategies is validated through numerical simulations for various initial engagement geometries. Furthermore, the performance of the proposed integrated guidance and control approach is also compared with the separate design of guidance and control subsystems, and shown to be superior.

Nonlinear integrated control with friction estimation for automatic lane change on the highways

A vehicle is a highly nonlinear dynamical system with high degrees of freedom. There are also very strong couplings between the longitudinal and lateral dynamics. Therefore, the simultaneous longitudinal and lateral motion control in different road conditions is a challenging problem. This paper presents an integrated adaptive control for longitudinal and lateral vehicle guidance on the highways. The contribution of this work is the design of a robust integrated controller that can handle tyre-road friction changes with low computational cost The proposed controller can adapt to the variations of tyre and road specifications. The strength of this method is that without the use of complex models, the nonlinear tyre dynamic is considered in the design of the controller. Therefore, despite the consideration of a comprehensive nonlinear vehicle dynamic model and the ability to adapt to changes in tyre and road specifications, the computational cost of the algorithm is very small. Besides, due to the controller robustness, there are no concerns about uncertainties. To validate the proposed algorithm, a full vehicle model in CarSim software is used. In obtained results, it is assumed that the yaw rate, longitudinal and lateral acceleration signals are available and have noises. The estimation of longitudinal and lateral velocities and other vehicle states has been done using these signals. Results for different road conditions as well as various vehicle movement modes confirm that tracking of longitudinal and lateral positions has been carried out with high precision. Besides, the results show that the proposed integrated control guarantees the stability of the vehicle, it will manage the tyre-road friction changes well, and also it is resistant to unmodeled uncertainties.

Identifying Potentially Risky Intersections for Heavy-Duty Truck Drivers Based on Individual Driving Styles

In developing countries, heavy-duty trucks play an important role in transportation for infrastructure construction. However, frequent truck accidents cause great losses. Previous studies have mainly focused on passenger drivers; to date, little has been done to assess the driving behavior of heavy truck drivers. The overall objective of this study is to classify driving styles at intersections, analyze the impacts of differing types of traffic control at intersections on driving styles, and identify potentially risky intersections. We selected 11 heavy-duty truck drivers and collected kinematic driving parameters (including driving speed and both lateral and longitudinal acceleration) from field experiments in Nanjing for our study. Our study on driving styles followed the following steps. First, we reduced data size and extracted data features on the basis of time windows in Python. Second, driving styles were classified into three driving styles: cautious, normal, and aggressive, based on the K-means clustering method, and the corresponding thresholds for each category were obtained. Kinematic driving parameters were used as driving style measurements. Third, according to classifications of driving style, the impacts of four different intersection traffic control types: two-phase signalized, multiphase signalized, stop, and yield intersections, on driving styles have been analyzed using the multinomial logit model. Moreover, based on the above analysis, potentially risky intersections were identified. The results suggest that different types of traffic control at intersections lead to variations in driving styles and have different influences on driving styles. In terms of accuracy, our method, which uses driving speed, both lateral and longitudinal acceleration, and jerk as features, performs better than traditional methods which only use speed and acceleration. The results of the study allow us to analyze the driving data of heavy-duty trucks and identify drivers who drive more aggressively during a trip. In addition, the results show that aggressive driving styles mostly occur at stop intersections and in the dilemma zones of signalized intersections. Therefore, early-warning interventions can be provided during a driver’s trip by analyzing the different types of traffic control at intersections on the route in advance. Finally, the cumulative analysis of driving styles at intersections over multiple trips can be used to identify potentially high-risk intersections. It is possible to eliminate potential risks in these areas through measures such as early warnings and by improving traffic management control methods.

Analysis of chest response characters for drivers in lateral and oblique automotive impact

Chest injury frequently occurs in oblique and side impacts. Apart from the loading of airbags and seatbelts, secondary impacts with door panels and armrests also cause severe chest injuries. This study aims to investigate the characteristics of the chest injury of occupants in the oblique and lateral impact. It focuses on the secondary impact between occupants and vehicle side structure. A model comprising GHBMC and components of Toyota Camry is established with acceleration curves. Combined with typical impact directions in NCAP tests, four sets of simulations are carried out. Results indicate that the maximum deflection occurs in oblique far-side impact, reaching 53 mm. Additionally, the maximum stress occurs in lateral near-side impact, reaching 259 MPa. In contrast, the stresses of far-side lateral and oblique impacts are only 2% and 3% smaller than the maximum one. Therefore, the occupant injury is serious in the far-side impact. Due to the lower lateral acceleration and the better seatbelt protection, the minimum deflection and stress are found in the near-side oblique impact. In conclusion, when the seatbelt can restrain the movement of the occupant during oblique and lateral impact, the injury level will be reduced. In addition, in the oblique and lateral impact simulations, the lowest rib stress exceeds the tolerance, while the highest chest deflection is still lower than the tolerance. This study provides a reference for the subsequent improvement of the restraint system.

Vehicle dynamics and active rollover stability control of an electric narrow three-wheeled vehicle: a review and concern towards improvement

Narrow electric three-wheeled vehicles are a potential solution to stringent issues of traffic congestion, parking space, vehicular emissions and the fuel crisis. However, narrow three-wheelers have poor manoeuvrability at high speed due to rollover propensity. Researchers have been addressing these conflicting requirements using an active tilt control, a concept of automatic tilting. This paper reviews the different methodologies of tilt control and vehicle dynamics of narrow three-wheeled vehicles, followed by major technical implications. The steering direct tilt control system based on an active steering gain curve has exhibited the substantial potential to control tilting to offer a minimum perceived lateral acceleration and tilting torque, such that the least deviation occurs in the desired path. However, the active steering gain curve can further be optimised by incorporating the desired tilt angle depending upon the rollover index of three-wheelers. The designed control system, including combined lateral and longitudinal dynamics needs to be investigated experimentally under various operating conditions like banked and graded roads, varying friction surfaces and multi-passenger configurations for severe manoeuvres over a large range of vehicle speed.

Impact of pitch actuator fault on 10-MW semi-submersible floating wind turbine

The pitch actuator of the offshore wind turbine has a high failure rate, and this fault will lead to aerodynamic imbalance on the floating system, especially when the 10 MW wind turbine is applied. In this paper, the impact of actuator faults on the floating platform motion and turbine structure is investigated. The 10-MW OO-Star semi-submersible platform is used as the reference structure. The fault discussed in this study involved one blade seizing, followed by an emergency shutdown. Coupled non-linear aero-hydro-servo-elastic simulations were carried out in the time domain using OpenFAST. The platform motions and structural loads caused by the fault were compared with the normal operating conditions. The effects of the pitch rate at the initial fault on the loads of the critical components are presented. The results revealed that imbalanced loads due to blade seizing can lead to particularly large excitations of the dynamic responses of the wind turbine. The maximum lateral nacelle acceleration is increased by 27.9%. In addition, the parametric study on the effects of the pitch rate for feathering blade was carried out. It was found that the pitch rate of 8 deg/s is favorable to alleviate the structural loads.

Analysis of Specific Physical Fitness in High-Level Table Tennis Players-Sex Differences.

Table tennis performance depends on multiple factors such as technique, tactics and fitness. Several studies have focused on investigating different technical-tactical variables. However, research analysing the specific physical qualities of this sport is scarce, particularly in the female sex. The aim of the present study was to assess the physical fitness variables associated with individual performance in elite table tennis players according to sex. Forty-eight elite players divided into males (n = 24; 25.38 ± 4.01 years) and females (n = 24; 22.33 ± 3.83 years) participated in the study. To determine physical fitness, participants performed vertical jump, hand grip strength, ergospirometry and lateral displacement tests (reaction time, displacement time and lateral acceleration). Male players showed higher values in vertical jump, hand grip strength and maximum oxygen consumption (p < 0.001). Likewise, male players moved laterally faster (p < 0.001). On the other hand, female players had a better reaction time towards the dominant side (p < 0.01). Elite male table tennis players showed better physical fitness compared to female players. Due to the scarcity of data on elite table tennis players, these results can serve as reference values for different table tennis practitioners.