Stability Of Car Research Articles

Robust control approach for stability and power quality improvement in electric car

Robust control approach for stability and power quality improvement in electric car

Minicircle DNA-Mediated CAR T Cells Targeting CD44 Suppressed Hepatocellular Carcinoma Both in vitro and in vivo.

PurposeBased on the continuous exploration of solid tumor immunotherapy, we focused on hepatocellular carcinoma with a high level of morbidity and mortality. We confirm the stability of mcDNA-based CAR T cell generating platform, and investigate the antitumor activity of CD44-CAR T cells against hepatocellular carcinoma both in vitro and in vivo.Materials and MethodsWe fused anti-CD44 scFv structure with transmembrane domain and intracellular domain. Using a non-viral mcDNA vector to load CD44-CAR gene, then transfected the mcDNA-CD44-CAR into human T cells by electroporation. We exhibited the transfection efficacy of CAR T cells and the CD44 expression of tumor cell lines by flow cytometry. The antitumor efficacy of CD44-CAR T cells in vitro and in vivo was detected through CCK-8 and ELISA assays, and xenograft mouse models, respectively.ResultsWe obtained mcDNA-CD44-CAR with a high level of density after repeated extraction and purification. The expression efficacy of CD44-CAR in T cells was more than 50% after seven days electroporation and the phenotype of CD44-CAR T cells was no difference compared with normal T cells. For CD44-positive hepatocellular carcinoma xenograft mice, CD44-CAR T cells had stronger tumor growth suppression compared to normal T and mock T cells. The same results occurred on the in vitro experiments including cytokine secretion and cytotoxicity assays. H&E staining graphs revealed that CD44-CAR T cells did not induce side effects in xenograft mice.ConclusionThe strategy for generating CAR T cells targeting cancer stem cell antigens was efficient and concise. The mcDNA had superior transgene ability without virus-related adverse effects. CD44-CAR T cells had strong suppression capacity against hepatocellular carcinoma.

Defining patterns in the longitudinal load on a train equipped with the new conceptual couplers

The longitudinal-dynamic load on a railroad train has been studied at its steady motion along the track of a homogeneous profile. A value of the longitudinal loading that a train is exposed to has been established. The calculations were carried out for a train consisting of 40 similar semi-wagons. The magnitude of the longitudinal loading, in this case, is taken to equal 1.2 MN. It is important to note that when increasing the motion speed, as well as the weight of a train, the magnitude of the longitudinal load may exceed the specified value. This contributes to the additional loading on the bearing structures of cars on the train and can cause damage to them. In addition, significant longitudinal-dynamic loads contribute to disrupting the motion stability of cars in the train. In order to reduce the longitudinal-dynamic efforts in the train under operating modes, including braking, it has been proposed to use, instead of a standard automatic coupling device, a conceptual coupler. In this case, the impact's kinetic energy is damped by transforming it into the work of a viscous resistance force. This resistance is created by moving a viscous liquid through the throttle holes of the piston based on the principle of hydraulic damper operation. To substantiate the use of a conceptual coupler, the calculation has been performed based on a method for determining the strength of the coupling device through the imaginary separation of a train into two parts. Taking into consideration a coefficient of the viscous resistance, which is created by the conceptual coupler, the acceleration experienced by a train reached about 0.8 m/s 2 . In other words, the use of a conceptual coupler makes it possible to reduce the longitudinal loading on a train by almost 30 % compared with the standard scheme of interaction between a locomotive and cars. The rod of the conceptual coupler has been estimated for strength. It has been established that the maximum equivalent stresses do not exceed permissible limits. The proposed measures would contribute to the reduction of a dynamic load on a railroad train under the loading modes of operation. The implementation of a given concept could also contribute to bringing down the damage to railroad stock in exploitation

STABILITY OF FREIGHT CARS UNDER THE ACTION OF COMPRESSIVE LONGITUDINAL FORCES

Purpose. The aim of the work is: a theoretical study of the car movement stability when exposed to longitudinal forces of a quasistatic nature; determination of analytical for estimating the longitudinal loading of cars in trains; the influence analysis of simultaneous action of certain factors on the value of longitudinal forces, at which the car movement stability is still preserved. Methodology. Assessment of the freight car stability when moving at different speeds along curved track sections was investigated using the analytical method. The most unfavorable schemes for applying compressive longitudinal forces in a vertical and horizontal plane are considered. Findings. Expressions are obtained for calculating the value of the car lift resistance coefficient by the longitudinal compressive force acting on the car as part of a freight train. The calculations were carried out in an empty and loaded state with a transverse run-up of the car body frame relative to the track axis in a guiding section of 50 mm in a curve of small radius taking into account the inertia forces from the unbalanced acceleration. Originality. In a theoretical study, the effect on the movement stability of quasistatic longitudinal compressive forces depending on the change in speed and the force value, as well as the effect of friction forces at the contact point of the wheel flange and rail and the eccentricity of fastening the tail of the automatic coupler, are considered. The influence of longitudinal compressive forces on the stability of freight rolling stock when moving in a curve of small radius with speeds up to a design value of 120 km/h is investigated. Practical value. The application of the results obtained by the above method will help to increase the stability of the freight rolling stock, which in turn will allow increasing the technical speed of train movement by removing some existing limits of permissible speeds. Using the described methodology for determining the car lift resistance coefficient will allow justifying the cause of wheel derailment, as well as to develop and put into practice the technical measures to prevent the lift of carriages, thrusts and shears of the track.

Straight running stability of automobiles: experiments with a driving simulator

The stability of the straight ahead running motion of automobiles is studied with proper theoretical tools pertaining to bifurcation theory. The study is both theoretical and experimental. Four theoretical models have been employed. They refer, respectively, to one simple car model, one simple driver model, one complex car model and one complex driver model. The existence of bifurcations, namely Hopf bifurcations, is found for both the simple car/simple driver model combination and for the complex car/complex driver model combination. The experimental study refers to the employment of a driving simulator in which a human driver controls the complex car model. At the driving simulator, bifurcations are found which correspond to the ones predicted either with the simple car/simple driver model combination or the complex car/complex driver model combination. At the driving simulator a chaotic motion is found, after a subcritical Hopf bifurcation has occurred. Apparently, for the first time in the sector of vehicle system dynamics, the actual existence of bifurcations and chaos has been shown for a real system with a human driver in-the-loop. The driving simulator does not seem introducing factors affecting sensibly bifurcations, so the bifurcations that have been found appear to be real, i.e. bifurcations could be found in an actual car running straight ahead.

Assessment of the stability and loading indicators of two-axle mine cars and rail tracks

The paper presents the research results of the stability and loading of the two-axle mine cars and rail tracks with various design for calculation schemes construction of transport systems of underground rail haulage. The dependences of changes in loading, stability and operation safety of rolling stocks from the parameters of irregularities, curvature radii of the rail track and the movement speed of rolling stocks at various technical solutions of the transport system, have been studied. The research results of the interaction between the two-axle mine cars and rail track with the gauge of 750 mm for underground rail haulage are presented. The parameters have been determined of the rail track irregularities in the horizontal and vertical planes, which cause the highest values of vertical and horizontal loads, acting on the rail track and the two-axle rolling stock. The recommendations are proposed for improving the study of the rail vehicles and regulatory documents development for the construction and operation of the track structure. The results can be applied for the underground rail haulage when creating the new vehicles for mines.

Estimation of Stability of Railway Flat Cars with Various Types of Running Gear Against Derailment

Estimation of Stability of Railway Flat Cars with Various Types of Running Gear Against Derailment

The calculation method of the length of contact of car tires with the road surface

In the tasks of modeling the motion stability, controllability and braking dynamics of cars and buses, information is required on the car tires contact length with the road surface. The car tires contact length is usually calculated from geometrical considerations (using the Hedekel formula). In this case, the experimental data of this value turn out to be less than the calculated ones due to the deformation features of the car tires. To account for this reduction in the contact patch length, the authors developed a general method for determining the correction coefficient. Previously, they developed a similar method for low-profile radial passenger car tires. Now it is valid for all passenger and truck tires. This will allow calculating the car tires contact length more correctly.

Research on race car steering geometry considering tire side slip angle

The steering trapezoid designed according to the Ackermann steering geometry potentially causes excessive tire wear and affects the steering performance due to the large tire deformation resulting from large lateral acceleration. To address these problems, this article introduces a design method for a race car steering system that considers the tire side slip angles to optimize the target steering angle relation. First, a racing path was planned by genetic algorithm according to the given race track and race car driver characteristics. Next, the objective function of the ideal steering angle relation was constructed by introducing the Ackermann correction coefficient and establishing the modified Ackermann steering geometry model, considering the tire side slip angle. Then, a data acquisition experiment was designed, and the Ackermann correction coefficient was identified by the proposed simulation algorithm. Finally, the coincidence degree of wheel steering centers was defined as the evaluation index, which can be used to describe and evaluate the performance of the coordination for wheels’ movement. Simulation results show that the design method of the steering system effectively improves the handling stability of the race car and reduces the tire leaning-grind.

Motion stability of railway cars on bogies 18-100

Stability of the rolling stock in a rail track is determined by the nature of the motion of the wheelsets under the influence of processes in the “wheel — rail” system and connections with the bogie and the carriage body. Factors affecting the motion of wheelsets are the irregularities of rail threads and the interaction forces in the “wheel — rail” system, which cause fluctuations in carriage hunting oscillation even in the absence of external disturbances. Parametric excitation of oscillations in the “carriage — track” system is caused by the difference in the radii of the rolling surfaces of the bevel gears with the transverse displacement of the wheelset in the track. This excitation is damped by the forces of resistance to rotation and displacement on the contact surface, the magnitude of which is inversely proportional to the rolling speed of the wheel. Therefore, with an increase in the speed of motion, the magnitude of resistance forces decreases and the intensity of processes determining hunting oscillations in the “wheel — rail” system increases. The excitatory factors on each of the wheelset of the bogie are of random nature and are not interconnected, therefore their vibrations are limited to the designs of the bogie and its connections with car body, which combine all the elements into a single system. Increasing the connectivity of the wheelsets and sidewalls of the bogie among themselves and with the carriage is the most appropriate solution for reducing hunting intensity. To do this, three-element bogies should reduce wear in the spring suspension, prohibiting the raising of the wedge above the plane of the supports of the bolster. To reduce the rotation of the bogie when hunting, bolster should be equipped with elastic contact bearings.

Rational acceleration control of an all-wheel drive vehicle

Problem. The improvement of ability rating of vehicles is a topical task which provides the promptness of transportation, improves the performance efficiency of vehicles by means of increasing the vehicle average speed. High dynamic characteristics are provided by mounting the powerful power units and by using the combined propulsion systems and powering cars recently. Using cars with driving wheels’ electric drive helps not only decrease energy consumption, but also increases car stability by regulating distribution of traction moments between the front and rear axles. Goal. The goal is to increase the course-keeping ability and power efficiency during the acceleration of all-wheel drive electric cars. Methodology. The provision of stability of vehicle movement is reached by the redistribution of total tangential reaction of a vehicle wheels. The power consumption of a power unit is determined with the help of rational law of the acceleration ramp changing during the acceleration that provides the most possible increase of line speed. Results. The relations allow to create the algorithm of control of vehicle front and rear wheels’ electric motors during the acceleration with the minimum of additional engine power consumption while accelerating with the maximum intensity that can be implemented both for electric cars and for cars with combined propulsion systems. Originality. The laws of driveline engine tractive effort torque control during the acceleration are obtained at the limit of a clutch fade of drive wheels with the road that determines the performance of maximum acceleration by cars. Practical value. Increasing of vehicle energy efficiency and providing of safety of traffic.Key words: electric car; stability of movement; power consumption; tractive effort torque.

Optimization of Design Parameters for Leaf Spring by Taguchi Technique

Spring design in vehicles is one of the basic requirements in the system of suspension as by ensuring the proper design, the necessary comfort for passengers can be obtained. Thus, the car's stability on the road and in different places (the flat roads, winding roads and mountain roads) will be achieved. Given this importance, there are many factors that affect the design of springs (leaf springs). This research includes the study of three factors considered namely :( thickness, length and step) of springs. Taguchi experiment is used in determining the best among the tests performed. Then each factor was taken individually in control to get the design parameters for the leaf spring. Taguchi technique is applied in the design process of the three factors and mix levels to choose the optimal level for each factor that gives nominal of suitable displacement, stress and load. Optimal levels that have been achieved for case study of leaf spring of a total thickness of (12) mm were: Spring work in regions with high bumps. Spring work in flat areas and highways. Spring work in the middle regions (winding roads within cities). Applied cases studied were NISSAN, SCANIA and MAN automobiles to apply this rule and compare the actual design specifications of these automobiles. The output results showed a complete compatibility between these cases.

Passenger Car Active Suspension System Model for Better Dynamic Characteristics

The technological investigations to a light passenger car have been carried out in order to improve the comfort and safety features by the implementation of an active suspension system. A fuzzy logic control-based active suspension system is proposed for the fuel-efficient small passenger cars to fulfil the design upgradation requirements. The proposed design comprised of hydraulically powered actuators is installed at each of the car wheels between sprung and unsprung mass to compensate the ground forces in order to resolve the instability and comfort issues. The dynamic analysis figures out the significant improvement of 12% in comfort and 11.53% in the car stability.

Influence of Driving Behaviors on the Stability in Car Following

Car following is the most common phenomenon in single-lane traffic. However, the propagation of the small perturbation of the velocity of the leading car will affect traffic flow. Driving behaviors play an important role in the determination of the qualitative dynamics of vehicles in the car-following process. Under different traffic environments, driving behaviors depend on the level of perceived risk, acceleration and deceleration habits, and reaction characteristics of the driver. The desired safety margin (DSM) model can directly describe the driving behaviors in the car-following process by using the parameters of the risk perception of drivers, sensitivity coefficient of acceleration and deceleration, and response time. In this paper, we investigate the influence of the accepted risk level, response time, and sensitivity factor on the traffic flow via the DSM model. The stability criterion of the simplified DSM model is derived via linear stability theory. Analytical results indicate that a backward propagating of perturbation would enlarge or shrink with the change of three driving behavior parameters of accepted risk level, sensitivity coefficient of acceleration or deceleration, and response time. Results show that careful driving can improve the stability of traffic flow and that system stability can be maintained by adjusting the acceleration and deceleration control parameters, increasing DSM, or decreasing response time for the adaptive cruise control or vehicular platoon control system. The results can provide reasonable values of driving behavior parameters for the stability of the primitive DSM model using the simplified DSM model. Furthermore, we analyze the influence of interval DSMs, and the acceleration and deceleration sensitivity of the primitive DSM model on the stability of traffic flow through numerical simulations. Results imply that the lower limit of the DSM influences traffic flow more significantly than the upper limit of the DSM. Moreover, the increase in deceleration sensitivity has a more important influence on the stability of traffic flow than the increase in acceleration sensitivity. The numerical simulation results are in good agreement with the analytical results and the relevant experimental results of previous studies.

ОЦЕНКА УПРАВЛЯЕМОСТИ ПОЛНОПРИВОДНОГО АВТОМОБИЛЯ ПРИ УСТАНОВИВШЕМСЯ ПОВОРОТЕ

This article discusses the conditions for increasing the stability and controllability of four-wheel drive vehicles with steady-state cornering. The aim of the study is to increase the stability and controllability of four-wheel drive vehicles in steady-state cornering. The article defines the conditions for the vehicle to lose trajectory stability and controllability when driving at a steady bend. When this goal was achieved, the following tasks were solved, namely, to determine the total lateral reactions on the front and rear wheels of the four-wheel drive vehicle, the total lateral reactions on the front and rear wheels of the four-wheel drive vehicle and the conditions for the loss of stability and controllability of the four-wheel drive vehicle when established, are presented cornering. An analysis of existing criteria shows various approaches to assessing the maneuverability properties of wheeled vehicles. Despite their diversity, the criteria for qualimetric assessment reflecting the influence of the parameters of wheeled vehicles and the road environment on stability and controllability are not sufficiently presented in the well-known literature. In well-known studies, the controllability of the car in the steady-state stage of the turning process was not considered. As you know, the driver must be able to, when acting on the steering wheel, acting on the steering wheel, ensure that the vehicle follows the curve of a constant curvature accurately. The study has been devoted to ensuring the controllability and stability of cars with steady motion in a straight line and at a turn. However, earlier in the work, the maximum adhesion indicators of the stability and controllability of the car with steady-state cornering were not considered. We have determined that angular acceleration of the car in the plane of the road with an unsteady turn is a criterion for controllability. Therefore, the achievement of the value is a condition for the loss of controllability of the car, and the achievement of the value is a condition for the loss of stability. Thus, the conditions for the loss of vehicle trajectory stability and controllability when driving at a steady bend at the preliminary design stage are determined, these parameters can be incorporated into the vehicle structure and its control system, which will increase vehicle safety and road traffic in general.

Dynamic modelling and simulation of rail car suspension systems using classic controls

Classic and advance control systems usually designed to improve the performance rail car suspension systems. In this study, the dynamic modelling and simulation of classic control for rail car suspension systems was carried out. Using nine degrees of freedom, the modelling process comprises of the representation of the rail car system with a schematic of the rail car body, its suspension system and rail track followed by the generation of equations of motion. The represented rail car system was simulated in the MATLAB-Simulink 2017a environment based on the equations of motion generated. Also, the proportional, integral and derivative (PID) control was employed to control the rate of disturbances based on the Ziegler-Nichols tuning rules. The results obtained indicate that the amplitude of oscillations, bandwidth and phase margin are key parameters that influences the stability of the rail car during movement. Also, the introduction of the PID control brought about significant reduction in the amplitude of oscillation, vibration, noise, rise time as well as rejection of disturbances and elimination of the steady-state error thereby increasing the stability and ride comfort of the rail car.

Development of a brake by wire system design for car stability controls

The paper presents the development of a vehicle stability control system that is able to operate in real time, ensuring to enhance vehicle dynamics and safety in all vehicle motion conditions, even at limit of handling. The commercial cars have an Electronic Stability System, ESC, that acts actuating the brakes autonomously to correct the vehicle dynamics at limit of adhesion conditions. In this study it will be shown how the stability control system proposed can operate autonomously and constantly during vehicle motion, thanks to a controller based on a simplified vehicle model and a brake unit that operates in continuous.The control system consists of a high-level control and four Brake-By-Wire actuators. The high-level control is an Linear Quadratic Regulator, LQR, that ensures to stabilize the yaw rate and the side slip angle minimizing the errors between the actual car values and the values given by a steady state dynamic reference model. To reach this aim the LQR gives the values of longitudinal forces that each wheel has to achieve. These values of force are sent by a CAN signal to the Cornering Brake Actuators, CBA, that with their own logic and proximity to the wheels ensure a vary fast actuation, stabilizing the vehicle and providing safety.To validate the control system a series of manoeuvres have been carried out on a case-study test bench, that has been installed on a static driving simulator equipped with a concurrent real-time machine, the complete vehicle network and the full steering system. The control system has been design to be used as a stability system on commercial cars, requiring of common vehicle sensors, ensuring better performances and stability even in driving at limit of adhesion conditions, but also to be installed in an autonomous vehicle being able to act independently from the driver.

Regarding the evaluation of car stability during lateral slips

The purpose of this paper is to highlight the analysis of the way in which the automobile can enter the state of instability when curving and the influence of some construction parameters (position of the weight centre, axle track, elasticity of the tires) and functional parameters (speed, acceleration, braking) which can influence the dynamic behavior. In this paper, there are described some dynamic simplified models of the automobile when curving, the way in which the experimental determinations have been made when a real automobile is involed in many circular routes with speeds and rays that we know. This paper also describes the methodology of study and the devices used as equipment for the automobile during the study on routes in order to register some specific parameters important for limiting the possibility of the appearance of lateral slips.

A Study on the Determination of the Tip-Over Stability of High Place Operation Car Using Multibody Dynamics Program and ZMP

A Study on the Determination of the Tip-Over Stability of High Place Operation Car Using Multibody Dynamics Program and ZMP

An extended macro model accounting for acceleration changes with memory and numerical tests

Considering effect of acceleration changes with memory, an improved continuum model of traffic flow is proposed in this paper. By applying the linear stability theory, we derived the new model’s linear stability condition. Through nonlinear analysis, the KdV–Burgers equation is derived to describe the propagating behavior of traffic density wave near the neutral stability line. Numerical simulation is carried out to study the extended traffic flow model, which explores how acceleration changes with memory affected each car’s velocity, density and fuel consumption and exhaust emissions. Numerical results demonstrate that acceleration changes with memory have significant negative effect on dynamic characteristic of traffic flow. Furthermore, research results verify that the effect of acceleration changes with memory will deteriorate the stability of traffic flow and increase cars’ total fuel consumptions and emissions during the whole evolution of small perturbation.