Vehicle Motion Stability Research Articles

Numerical investigation of vehicle water entry with angle of attack

This paper investigates the water entry of a vehicle with angle of attack (AOA) through numerical methods, employing the volume-of-fluid multiphase flow model and overset grid technique. The validity of the numerical model is confirmed through experimental verification. Building upon this, the study analyzes the motion characteristics, cavity evolution, and flow field distribution of the vehicle during water entry, considering the influence of AOA and falling velocity. Numerical findings indicate that the collapse of the right side of the cavity induces a transient lateral force on the vehicle, resulting in vehicle tilting. Moreover, an increase in initial velocity delays vehicle tilt, while an increase in AOA reduces vehicle motion stability, leading to earlier tilting. Initially, the vehicle rotates counterclockwise around the Oz axis of the projectile coordinate system. Subsequent to cavity collapse, the vehicle experiences an opposing moment, leading to a reduction in rotation speed and eventual rotation in the opposite direction. Water impact triggers sudden changes in the vehicle's lift and drag coefficients, while cavity sticking induces a minor abrupt change in the lift coefficient. Following cavity collapse, both lift and drag coefficients exhibit significant oscillations. Unlike typical cavity collapse phenomena, the flow field on the right side of the vehicle undergoes alternating high-pressure and low-pressure regions.

Numerical Study of the Ultra-High-Speed Aerodynamically Alleviated Marine Vehicle Motion Stability in Winds and Waves

The ultra-high-speed aerodynamically alleviated marine vehicle (AAMV) is a high-performance vessel that combines a hydrodynamic configuration and an aerodynamic wing to reduce wave-making resistance during the high-speed planing phase. The forces of the AAMV exhibit strong nonlinear and water–air coupling characteristics, resulting in particularly complex motion characteristics. This paper presents a longitudinal and lateral stability model of the AAMV, which considers the effects of aerodynamic alleviation. Additionally, a numerical model of wind and wave turbulence forces is established, which considers viscous correction based on the potential theory. Finally, the effect of wind and wave turbulence forces on the motion stability of the AAMV under regular and irregular waves is analyzed by numerical solution. The simulation results demonstrate the influence of these disturbance forces on the stability of the AAMV under different sea states. The motion parameters of the AAMV exhibit a pronounced response to changes in sea state level. The aerodynamically alleviated effect is enhanced as speed increases, and the influence of winds and waves on the AAMV is greatly weakened, reducing the possibility of instability. During the cruising phase under class V sea state, the pitch, roll, and heave response are 0.210°, 0.0229°, and 0.0734 m, respectively. This effect can effectively improve the motion stability of the AAMV in winds and waves.

Experimental study on the water entry of a vehicle with a single canard wing at an initial angle of attack

The use of flow control techniques is important to enhance vehicle motion stability during water entry. This paper introduces a method that applies a canard wing to the water entry problem, and the vertical water-entry process of a vehicle with a single canard wing at an initial angle of attack was experimentally studied. The cavity evolution and vehicle kinematics during water entry at various impact velocities and initial angles of attack were investigated. The results indicate that the fore-end cavity and the attached cavity on the wing are features of a vehicle with a canard wing during water entry. Unlike a wingless vehicle, the canard-wing configuration provides a restoring moment that corrects the deflection of the trajectory and attitude. As the impact velocity increased, the vehicle trajectory gradually corrected to a vertical straight-line trajectory before deflecting in the direction opposite to the side without a wing. As the initial angle of attack increased, the vehicle trajectory gradually shifted towards the side with the wing; however, the attitude remained stable without continuous deflection. The canard wing prevents a continuous change in attitude deflection caused by the initial angle of attack.

BIZON–UGV for Airport Pavement Testing: Mechanics and Control

The paper presents a study of the performance and development of unmanned ground vehicles (UGVs), establishing mathematical and numerical models of the chassis system. The model analysis is performed by 3D software package SolidWorks 2018 with finite element discretization. The mesh modelling and analysis are focused on studying the strength and stiffness of the robotic platform chassis and the distribution of stress and deformation in the extremal condition. The paper also presents an autopilot design with a new cascade control system for the autonomous motion of an unmanned ground vehicle based on proportional–integral–derivative (PID) and feedforward (FF) control. The PID-FF controller is part of a UGV used in a hybrid control system for precise control and stabilization, which is necessary to increase the vehicle motion stability and maneuver precision. The hybrid PID-FF control system proposed for the ground vehicle model gives satisfactory control quality while maintaining the simplicity of the control system. The presented tests performed in mechanical design and control analysis give good results and prove the usefulness of the designed unmanned device.

Global stability of road vehicle motion with driver control

The paper contributes to unveil how drivers—either human or not—may lose control of road vehicles after a disturbance. First, a simple vehicle-and-driver model is considered: Its motion is characterized by the existence of limit cycles whose amplitude depend on vehicle forward velocity (both oversteering and understeering vehicles may exibit this property). Such limit cycles are originated by a Hopf bifurcation occurring at a relatively high vehicle forward velocity. A mathematical proof of the existence of Hopf bifurcations is given. The existence of Hopf bifurcations and saddle limit cycles is confirmed by experimental tests performed by a dynamic driving simulator with a complex vehicle model and human in the loop. By a Zubov method, a Lyapunov function is derived to compute the region of asymptotic stability for the simple vehicle-and-driver model. A necessary and sufficient condition is derived for global asymptotic stability. Such a condition refers to the variation of the kinetic energy which must vanish at the end of the disturbed motion. This occurrence has been detected at the driving simulator too. Just a single stable equilibrium has been found inside the domain of attraction in all of the examined cases.

A Linear Variable Parameter Observer-Based Road Profile Height Estimation for Suspension Nonlinear Dynamics Improvements

The accuracy of road profile height estimation has a significant impact on suspension control quality, which in turn influences handling, stability of vehicle motion and occupants' comfort. Based on our previous published work, this article designs and proposes a novel method for road profile estimation that is based on suspension nonlinear dynamics. The proposed approach first establishes the road profile height estimation model considering a real suspension design, including nonlinear characteristics of the shock absorber, bushing stiffness and damping, actual geometry of the control arms, and positioning of absorber. Unlike the conventional sprung-unsprung mass model, the real nonlinear suspension model provides much higher output prediction accuracy as computational and experimental results demonstrated. Moreover, the established estimation method and model require only two easily measurable parameters, which are the acceleration of the sprung mass and the travel of the shock absorber. While considering nonlinearity and hysteretic characteristics of the damping force, the proposed approach is based on the estimation framework of linear parameter-varying systems and establishes a sliding mode observer for estimating the road profile height. The stability of estimation error dynamics of the observer is guaranteed by the Lyapunov stability analysis. As bench-test experiments of a hardware implementation of the suspension-wheel unit validated the computational results. The tests demonstrated that the proposed method allows for real-time estimating of the road profile height in different road conditions and electric currents of the suspension damper and is robust to uncertainty of the payload.

Lateral Vehicle Trajectory Planning Using a Model Predictive Control Scheme for an Automated Perpendicular Parking System

This article proposes a lateral vehicle trajectory planning and control algorithm using a model predictive control (MPC) scheme for an automated perpendicular parking system. Previous work showed that approximated clothoid-based local path planning using a virtual towing distance provides low computational time and the stability of lateral vehicle motion in a parking system. However, this approach cannot function in certain parking situations and may cause undesirable steering maneuvers due to state-dependent planning. We present a new approximated clothoid path based on lateral vehicle kinematics to cope with these problems. Using the proposed kinematic model, we formulate an MPC problem for path planning. Then, the proposed lateral vehicle trajectory planning becomes an MPC problem under constraints. Besides, we show that lateral vehicle motion for vertical parking can be implemented using simple kinematic lateral motion control. Experimental results show that the vehicle with the proposed method moves smoothly and completes the given parking mission under constraints, even under tight parking space conditions.

An analysis of turning stability dynamics of TERA 240 truck by the four - Wheeled planar vehicle dynamic model

The turning dynamic features to ensure stable and safe conditions of the TERA 240 truck are investigated using the four-wheeled planar dynamic model, in which the force components from 4 wheels are taken into account to build a computational model with the time-varying steering angle is used. The necessary input parameters of the TERA 240 vehicle for the vehicle planar dynamic model are determined on the basis of the available actual vehicle, with all 3 loading cases are noload, half-load and full-load. The kinematic and dynamic parameters describing the vehicle's planar turning motion are determined, resulting in the basement for evaluating the vehicle's motion stability. The calculation process is performed in the velocity domain to ensure the ultimate stability condition that the vehicle does not slide or overturn when turning. The obtained results are analyzed to evaluate the vehicle's turning stability performance, based on the variable relationship of the parameters in the investigated cases: turning radius is constant, velocity is constant, and steering angle is constant. The vehicle's turning stability is specifically defined: the vehicle is understeer with no-load case, the vehicle is oversteer with half-load and full-load cases.

Modeling the steering wheel influence by the driver on the vehicle's motion stability

In this article, a mathematical model was developed to influence the intensity of the steering wheel turn by the driver on the vehicle's stability. Comparison of the developed mathematical model with the experiment results made it possible to establish their adequacy. The effect of the three conditional drivers on the intensity of the steering wheel was examined. When performing the 'J-turn' maneuver, comparing the indices of the 1st, 2nd and 3rd conditional drivers, their proximity to the requirements of the standard was established. It was found that the indices of the second conditional driver are closest to the standard requirements. When performing the 'Single Lane Change' maneuver by the first conventional driver, the standard deviation value from the specified trajectory was 0.102, and the correlation index was 0.88.

Decoupled Longitudinal and Lateral Vehicle Control Based Autonomous Lane Change System Adaptable to Driving Surroundings

The purpose of this study is to develop an autonomous lane change control system that adapts to variable surrounding conditions, to ensure vehicle safety and traffic flow stability. In this paper, we propose decision-making and control procedures for realizing autonomous lane changing; to this end, we consider not only behaviors for changing lanes but also those involved in approaching the lane changing state, with a focus on the controller design. A decoupled control structure and longitudinal trajectory-free control approach are suggested. We design a novel inter-vehicle spacing policy and a 3DOF lateral error vehicle dynamics model. To verify the effectiveness of our system, simulation experiments are performed for 12 scenarios, and system assessments are conducted based on four evaluation perspectives. The results confirm that our system can safely control the vehicle amidst various surrounding vehicle conditions and can also ensure vehicle motion stability. Furthermore, we solve the existing dynamic instability problem of lateral control, which arises through longitudinal acceleration variability. Another significant advantage of this model is that the controlled vehicle does not interfere with the target-lane traffic flow and smoothly synchronizes with the flow during lane changing.

Transferring From Automated to Manual Driving When Traversing a Curve via Haptic Shared Control

Under certain scenarios, an automated driving system (ADS) might need to transfer steering control to the human driver. Even if the driver is ready to take over, an abrupt control transition when traversing a curve can lead to unstable steering. This is because the steering wheel is balanced by both the self-aligning torque and ADS torque; if the latter suddenly disappears, the balance is lost. In this study, we developed a method for transferring control when traversing a curve via haptic shared control. A driving simulator experiment was conducted to verify the effectiveness of the proposed method. The results demonstrated that the proposed method exhibits better steering and vehicle motion stability than a non-shared control method.

Four-Wheel Independent Drive Electric Vehicle Stability Control Using Novel Adaptive Sliding Mode Control

Four-wheel independent drive is an important research topic for the future development of pure electric vehicles (EVs) due to its fast response and great flexibility of path tracking. One of the critical issues is to maintain the vehicle motion stability of the four-wheel independent drive (4WID) EV (4WID EV) by appropriately distributing the torque of each wheel. The article presents a hierarchical control structure to counteract the stability problems caused by the actuator faults and road friction uncertainties. Instead of using linear control at the top-level (i.e., the outer control loop), a novel sliding mode controller with adaptive proportional-integral (PI) sliding surface is designed to achieve the required virtual control signal. For the bottom-level controller (or the inner loop controller), dynamic control allocation is employed to optimally allocate the required actual torque for each wheel. The stability of the overall closed-loop system is successfully achieved and proved by using the Lyapunov method. The proposed controller has been tested via simulation and experiments with various actuator faults and road conditions. All the test cases showed the superiority of the proposed method compared to some of the currently existing 4WID control strategies.

Analysis of the loss of vehicle motion stability in the conditions of steering control disturbance

Disturbances in the vehicle motion may be caused by different factors and in many cases are the reason for dangerous traffic incidents. Disturbances within the human-vehicle system are particularly hazardous. An innovative method was designed for analyzing and simulating the process of loss of vehicle motion stability after interference in the steering system, e.g. by acting on the steering wheel by the passenger. The subject of the study is the theoretical and experimental analysis of the vehicle motion path kinematics together with the duration of the disturbance, driver’s reaction time and steering wheel turning angles. PC-Crash simulation software was employed for the purpose of studying the disturbance characteristics and their influence on the loss of vehicle motion stability. It is recognized that the studied issues are as yet poorly understood, the presented results expand our knowledge base in this area and can be employed for the purpose of analysis of actual traffic accidents.

High-speed vacuum air vehicle

Background: There are a number of problems in the prior art, those are topics of research inputs likes ranges of the drag force generated by the vehicle, lift force at high vehicle motion velocities for compensation of the vehicle weight, Aerodynamic aspects of operation of the vehicle,
 Aim: Stream wise stability of vehicle motion and levitation and breaking of the vehicles and supersonic speed is not achieved in any mode of transportation. But this present invention related to high speed magnetic levitating transportation. More particularly, present invention is related to high speed magnetic levitating transportation using compressed air chamber in the transportation vehicle.
 Methods: The present invention is more particularly related to high speed vehicle levitated on a vacuum tunnel by using electromagnetic levitation. As this vehicle will move from one place to another in a vacuum environment and this vehicle will levitate above track with the help of electromagnets.
 Results: The important thing is its motion, which is possible due to reaction force of high pressure air, coming out from compressed air chamber present in vehicle.
 Conclusion: It can give us the acceleration as per load requirement and it can achieve supersonic speed in few seconds.

Method of controlling innovative articulation for articulated vehicle

Operation of an articulated vehicle is dependent on an appropriate damping action taking place in its rotary articulation. In order to analyse an impact of the control of the articulation on the motion of the vehicle a model of the vehicle with a controllable hydraulic damping system has been developed. A 90 degree turn and lane change manoeuvres were simulated using LabVIEW software. Modification of the damping parameters of the articulation, according to the velocity and articulation angle of the vehicle, proved to have a significant impact on the vehicle motion stability. Moreover, the sensor layer necessary for the control algorithm as well as the diagnostic system is described.

Effect of vehicle motion stability after impact/crash on traffic safety

The article presents the application of general stability theory to the study of road traffic stability immediately after an impact (crash, collision). It turns out that when modelling a collision, vehicles can be treated as colliding masses and dynamical systems can be assigned to this phenomenon.

Investigation of PID Control Model Performance in Off-road Working Vehicle Motion Stability Control System

This paper focuses on tip-over problem of orchard vehicle, establishes vehicle dynamic model with 7 degrees of freedom (DOF), and proposes a vehicle motion stability control method based on real-time adjustment of vehicle posture parameters, relies on ADAMS and MATLAB to set up co-simulation control model, and conducts vehicle scale model motion stability control simulation and test. Analysis of simulation result shows that vehicle motion stability control model mentioned above can effectively prevent orchard vehicle tip-over accidents. To verify simulation result, vehicle state parameter collection system is established to acquire information on vehicle velocity and posture in real time. It is found in the same environment, including road conditions and parameter adjustment, vehicle scale model test and co-simulation result have a basically consistent variation tendency. When vehicle encounters tip-over accident, angles such as pitching angle vary rapidly. In anti-tip-over control process, pitching and rolling angle have greater influence on vehicle motion stability. If Kp and Kd are adjusted properly, good vehicle motion stability control effect is acquired.DOI: http://dx.doi.org/10.5755/j01.eie.23.2.17256

Analysis on Multistable Motion Characteristics of Supercavitating Vehicle

Due to complex underwater environment, when the initial condition of launching is subjected to low external disturbance, the motion trace of a supercavitating vehicle might display many different motion states during underwater navigation. With the aim of addressing this problem, based on the dynamic map, in the present work the multistable phenomena of attractor coexistence of the supercavitating vehicle system under various initial conditions were analyzed and the initial condition effects on the multistable motion characteristics were investigated through the domains of attraction, time, and frequency. The results demonstrated that, unlike the ordinary dynamic systems, a supercavitating vehicle demonstrates multistable phenomena, such as the coexistence of the stable equilibrium point and the limit cycle and the coexistence of the limit cycle and the chaotic attractor, along with the coexistence of diversified limit cycles; under fixed system parameters, as the initial condition of launching varied, the vehicle displayed various motion states; in engineering practices, the initial condition of launching could be adjusted according to the domain of attraction, in order for the vehicle motion stability to be enhanced.

Study on Orchard Vehicle Motion Stability Control System

Abstract: This paper focuses on tipover problem of orchard vehicle, establishes vehicle dynamic model with 7 degrees of freedom (DOF), proposes a vehicle motion stability control method based on real-time adjustment of vehicle posture parameters and relies on vehicle scale model motion stability control test. Analysis of test result shows that vehicle motion stability control model mentioned above can effectively prevent orchard vehicle tipover accidents. When vehicle encounters tipover accident, angles such as pitching angle vary rapidly. In anti-tipover control process, pitching and rolling angle have greater influence on vehicle motion stability. If K p and K d are adjusted properly, good vehicle motion stability control effect is acquired.

Dynamic Detection of Vehicle Motion Stability Based on Time-varying Damping Ratio

In order to dynamically detect vehicle motion stability during operation, as a new method of detecting vehicle motion stability, the time-varying damping ratio, is presented on the basis of the analysis of the dynamic response feature and the non-stationary characteristics of the response signals. The lateral vibration accelerations are decomposed by the IEMD(improved empirical mode decomposition) into a finite and often small number of IMF(intrinsic mode functions). The instantaneous frequency and the instantaneous amplitude of the intrinsic mode components are drawn through normalized Hilbert transform, respectively. The time-varying damping ratios under different intrinsic modes are computed by applying instantaneous amplitude and instantaneous frequency to judge the running stability of the vehicle. The zero or negative damping ratio indicates that the vehicle is unstable, the positive damping ratio shows that the vehicle keeps stable, the absolute value of the negative ratio means the severity of vehicle instability. Through the theoretical and experimental verification applying simulation and the measured signals, the results show the method can accurately and efficiently dynamically capture the time-varying characteristics of the system stability, with a powerful method for transit monitoring of vehicle running stability.