Vehicle System Model Research Articles

Vibration control of bridge subjected to multi-axle vehicle using multiple tuned mass friction dampers

The effectiveness of tuned mass friction damper (TMFD) in reducing undesirable resonant response of the bridge subjected to multi-axle vehicular load is investigated. A Taiwan high-speed railway (THSR) bridge subjected to Japanese SKS (Salkesa) train load is considered. The bridge is idealized as a simply supported Euler–Bernoulli beam with uniform properties throughout the length of the bridge, and the train’s vehicular load is modeled as a series of moving forces. Simplified model of vehicle, bridge and TMFD system has been considered to derive coupled differential equations of motion which is solved numerically using the Newmark’s linear acceleration method. The critical train velocities at which the bridge undergoes resonant vibration are investigated. Response of the bridge is studied for three different arrangements of TMFD systems, namely, TMFD attached at mid-span of the bridge, multiple tuned mass friction dampers (MTMFD) system concentrated at mid-span of the bridge and MTMFD system with distributed TMFD units along the length of the bridge. The optimum parameters of each TMFD system are found out. It has been demonstrated that an optimized MTMFD system concentrated at mid-span of the bridge is more effective than an optimized TMFD at the same place with the same total mass and an optimized MTMFD system having TMFD units distributed along the length of the bridge. However, the distributed MTMFD system is more effective than an optimized TMFD system, provided that TMFD units of MTMFD system are distributed within certain limiting interval and the frequency of TMFD units is appropriately distributed.

Embedded Based Smart, Secured and Safe Vehicle System

In today's fast and crowded world, road accident is a major concern. The highest fatal traffic accidents occur on the curved roads at night time. Also the glare problem due to focus of headlight is dangerous. Even the improper indications given to the nearby vehicle increases chances of fatal accidents. These facts indicate the importance of advancement in conventional vehicle systems. This paper explains the prototype model of vehicle system consisting of intelligent headlight intensity control, adaptive headlights, auto indicator-off system, anti-collision system and vehicle to vehicle communication. Proposed system is very cost efficient and reliable and can be mounted on any vehicle, it is specially focused to increase the safety and security of low-end vehicles.

Vehicle Lateral Dynamics Control Through AFS/DYC and Robust Gain-Scheduling Approach

In this paper, we investigate the combined active front-wheel steering/direct yaw-moment control for the improvement of vehicle lateral stability and vehicle handling performance. A more practical assumption in this work is that the longitudinal velocity is not constant but varying within a range. Both the nonlinear tire model and the variation of longitudinal velocity are considered in vehicle system modeling. A linear-parameter-varying model with norm-bounded uncertainties is obtained. To track the system reference, a generalized proportional-integral (PI) control law is proposed. Since it is difficult to get the analytic solution for the PI gains, an augmented system is developed, and the PI control is then converted into the state-feedback control for the augmented system. Both the stability and the energy-to-peak performance of the augmented system are explored. Based on the analysis results, the controller-gain tuning method is proposed. The proposed control law and controller design method are illustrated via an electric vehicle model.

Analysis of steering system elasticities and their impact on on-centre handling

This paper deals with the analysis of the elasticities of a steering system regarding the on-centre of the steering system. In the first part, different subsystems of the steering system are analysed in detail. Therefore, several test drives on a steering test rig and a reference vehicle are executed. On the basis of the experimentally determined results, a vehicle and steering system model is built. The parameterised model is used to analyse the characteristics of the steering system in the on-centre handling range. The results show that the elasticities of the steering system have significant influence on the vehicle and steering dynamics response.

Hierarchical Control Algorithm for Stability Enhancement of 4WD Electric Vehicle with In-Wheel Motors

According to the characteristic that each wheel torque of 4WD electric vehicle is independent controllable, the control allocation method with hierarchical structure to optimize the distribution of motor torque can improve the handling stability of the vehicle. The controller is composed of an upper controller and a lower distributor, of which the upper controller can calculate the generalized force of longitudinal force and yaw moment that the vehicle needed based on the vehicle state, and the lower controller is used to figure out the torque allocated to each wheel. The whole vehicle and steering system models are established for simulation and demonstration through the application of Matlab and Simulink. The simulation results show that the control allocation method with hierarchical structure can effectively improve the handling stability of the vehicle.

Research and Simulation of the Electrical Vehicle Based Dynamical System

This study developed a dynamic model of electric vehicle system by using the MATLAB/Simulink tool. The vehicle model comprises two system components: an electrical system and a suspension system. This study also designed various road conditions for simulating the motion of vehicle traveling along a road. The results show that the electrical and suspension system parameters can be adjusted immediately to enhance passenger comfort. The findings of this research have practical teaching applications. Students can modify the vehicle model parameters byes using the MATLAB graphical user interface, allowing them to observe the motion of vehicle under various road conditions.

Improved Drive Cycle Following with an ILC Supported Driver Model

Drive cycle following is important for concept comparisons when evaluating vehicle concepts, but it can be time consuming to develop good driver models that can achieve accurate following of a specific velocity profile. Here, a new approach is proposed where a simple driver model based on a PID controller is extended with an Iterative Learning Control (ILC) algorithm. Simulation results using a nonlinear vehicle and control system model show that it is possible to achieve very good cycle following in a few iterations with little tuning effort. It is also possible to utilize the repetitive behavior in the drive cycle to accelerate the convergence of the ILC algorithm even further.

Numerical modeling and active noise control of impact road noise inside a vehicle compartment

Even though active noise control (ANC) technique has been widely investigated and proven its efficiency for low-frequency vehicle interior noise control, current applications are mainly for the steady noise process such as powertrain noise and uniform road noise. When impulsive road disturbances due to road bumps or potholes are present, they may hinder the performance of the ANC system. One of the reasons is that the prevalent ANC algorithm, namely the filtered- x least mean square (FxLMS) algorithm, has been developed assuming that the signals follow the normal distribution. The impact road noise due to a sudden impact may exhibit a non-Gaussian characteristic. Hence, the FxLMS algorithm may not be appropriate for controlling this type of impulsive noise. In this study, a robust ANC system configured with a modified FxLMS (MFxLMS) algorithm by incorporating thresholds on reference and error signal paths is proposed for impact road noise control. To aid in the control system design, the spectral-based substructuring technique is implemented to develop a coupled vehicle system model to simulate the impulsive interior acoustic response due to road unevenness. The vehicle passenger compartment is simplified as a 3-dimensional flexible-panel backed cavity model, which is coupled with the tire-wheel system modeled as a flexible ring element and rigid wheel through the suspension system represented by a spring-damper model. The tire-road interaction is modeled as a set of flexible elements with certain stiffness over a half-cosine wave road bump. Numerical simulation results show that the proposed ANC system can effectively deal with the interior impact road noise without instability issue that may occur in the existing FxLMS algorithm. In fact, results show that approximately 8 dB reductions are achieved at the driver's ear position.

Model-based diesel Engine Management System optimization for transient engine operation

A recently developed strategy to calculate set points for controllable diesel engine systems is described, further developed, and evaluated. The strategy calculates set points with an aim to minimize fuel consumption for a given dynamic vehicle driving cycle, while keeping accumulated emissions below given limits. The strategy is based on existing methodology for steady-state engine operation, but extended to handle transient effects in the engine caused by dynamics in the engine air system. Using the strategy, set points for the complete operating range of the engine can be calculated off-line and stored in an Engine Management System, hence set points can be derived for any (steady-state or transient) driving scenario. The strategy has been evaluated using a simulation model of a complete diesel engine vehicle system. The model estimates fuel consumption, NOX, and soot emissions for a dynamic vehicle driving cycle depending on set points for boost pressure, oxygen fraction in the intake manifold, and injection timing, throughout the simulation. Using this simulation model, the strategy has been shown to decrease fuel consumption for the New European Driving Cycle with 0.56%, the Federal Test Procedure with 1.04%, and the Japanese JC08 cycle with 0.84% compared to a strategy based on steady-state engine operation.

A Transient Diesel EMS Strategy for Online Implementation

A recently developed strategy for diesel engine management systems is modified to reduce the implementation complexity. The strategy calculates set points for engine management system controllable quantities with an aim to minimize fuel consumption for a given engine speed and requested torque profile, while keeping accumulated emissions below given limits. The strategy is based on the methodology for steady-state engine operation, but extended to handle transient effects in the engine caused by dynamics in the air system. The strategy leads to the parametrization of mappings with two, three and four input dimensions respectively. In this paper, a modification of the strategy is proposed such that the memory demanding multidimensional mappings can be approximated in an engine management system using only two-dimensional grid maps. The modified strategy has been evaluated using a complete diesel engine vehicle system model simulating the NEDC driving cycle. The performance of the modified strategy has been compared with the original performance of the strategy. It is demonstrated that the modification of the strategy has very little impact on resulting performance of a vehicle but requires considerably less memory for implementation.

Power Smoothing Energy Management and Its Application to a Series Hybrid Powertrain

Energy management strategies in hybrid electric vehicles determine how much energy is produced/stored/used in each powertrain component. We propose an approach for energy management applied to a series hybrid electric vehicle that aims at improving the powertrain efficiency rather than the total fuel consumption. Since in the series configuration the engine is mechanically decoupled from the traction wheels, for a given power request the steady-state engine operating point is chosen to maximize the efficiency. A control algorithm regulates the transitions between different operating points by using the battery to smoothen the engine transients, thereby improving efficiency. Because of the constrained nature of the transient-smoothing problem, we implement the control algorithm by model predictive control. The control strategy feedback law is synthesized and integrated with the powertrain control software in the engine control unit. Simulations of the urban dynamometer driving schedule (UDDS) and US06 cycles using a complete vehicle system model and experimental tests of the UDDS cycle show improved fuel economy with respect to baseline strategies.

Modeling and Velocity Control for a Novel Narrow Vehicle Based on Mobile Wheeled Inverted Pendulum

Traffic problems such as pollution and congestion are becoming more and more serious in urban areas. A potential solution to these problems is to develop narrow vehicles that occupy less space and have lower emissions. There has been increasing interest in underactuated mechanical systems, i.e., mobile wheeled inverted pendulum (MWIP) models, which are widely used in the field of autonomous robotics and intelligent narrow vehicles. A novel narrow vehicle based on an MWIP and a movable seat, called UW-Car, is investigated in this paper. The dynamic model of the underactuated vehicle system running on flat ground is derived by Lagrange's equation of motion. Based on the dynamic model and terminal sliding mode control method, two terminal sliding mode controllers are designed to control velocity and braking of the UW-Car. The first one is used to control the forward speed to a desired value while keeping the body upright and the seat on some fixed position. The second one is a switching sliding mode controller, composed of three terminal sliding mode controllers that quickly brakes the system according to an optimal braking scheme. All the control algorithms are tested in both Matlab simulation and a UW-Car experiment. The simulation and experimental results demonstrate the efficiency of the model and controllers.

Analysis of driving mode effect on vehicle stability

Nowadays the typical method of dynamics analysis of vehicle stability is based on the nonlinear vehicle model deriving from the classic two degrees of freedom (2DOF) linear vehicle model. The features of system stability are obtained by phase space analysis, state variables analysis and so on. But these conclusions are drawn under the assumption that the driving mode effect on vehicle stability is neglected in vehicle model. In fact, there are strikingly obvious stability differences between front-wheel-drive vehicle and rear-wheel-drive vehicle at the high speed. Aiming at the above problem, this paper has investigated effect of driving mode on vehicle stability. A uniform slip equation of tyre longitudinal slip is proposed. The uniform slip equation guarantees both the calculation validity and the simulation convenience. Based on the uniform slip equation and Magic Tyre Formula, a 5DOF (longitudinal velocity, lateral velocity, yaw rate, front wheel rotational velocity and rear wheel rotational velocity) planar motion nonlinear dynamics vehicle system model is established under the consideration of driving mode. Many simulations are carried out on the basis of the 5DOF nonlinear mechanical vehicle model with different driving modes and different front steering angles respectively. The simulation results, including system globe phase portraits, system state variables, vehicle tracks and tyre force distributions, show that the driving mode has great effects on vehicle stability. The present vehicle models without considering driving mode fail to estimate the system stability region exactly.

Coupled Vibration Analysis of Vehicle-Bridge System Based on Multi-Boby Dynamics

For establishing the refined numerical simulation model for coupled vibration between vehicle and bridge, the refined three-dimensional vehicle model is setup by multi-body system dynamics method, and finite element method of dynamic model is adopted to model the bridge. Taking Yujiang River Bridge on Nanning-Guangzhou railway line in China as study background, the refined numerical simulation model of whole vehicle and whole bridge system for coupled vibration analysis is set up. The dynamic analysis model of the cable-stayed bridge is established by finite element method, and the natural vibration properties of the bridge are analyzed. The German ICE Electric Multiple Unit (EMU) train refined three-dimensional space vehicle model is set up by multi-system dynamics software SIMPACK, and the multiple non-linear properties are considered. The space vibration responses are calculated by co-simulation based on multi-body system dynamics and finite element method when the ICE EMU train passes the long span cable-stayed bridge at different speeds. In order to test if the bridge has the sufficient lateral or vertical rigidity and the operation stability is fine. The calculation results show: The operation safety can be guaranteed, and comfort index is “excellent”. The bridge has sufficient rigidity, and vibration is in good condition.

Evaluation of the Head Kinematics of the Q3 Model and a Modified Q3 Model by Means of Crash Reconstruction

Objective: One objective of this study is to evaluate the head kinematics of the Q3 model. Another objective is to evaluate the effect on head kinematics of increased thoracic spine flexibility; more humanlike mass distribution; and more humanlike body geometry in the Q3 model. The evaluations were based on the head kinematics of children deduced from real crashes and on new data of mass distribution and updated body dimensions for 3-year-olds. Methods: The head kinematics of the Q3 model was evaluated by comparing the Q3 model's head displacement response with the deduced response of 3-year-old children in real crashes. To do so, data from crashes were collected. The data were used to develop the mathematical vehicle and restraint system models (MADYMO, TASS, the Netherlands). Three crashes involving 3-year-old children in frontal impacts were reconstructed. The models were run 35 times each (one model per crash), each time with a different setting to each of the variables for which the exact value was not known. Examples of those variables include crash pulse, initial dummy position, and initial seat belt position. Two versions of the Q3 model were used: one that correlated with the Q3 ATD and one that was modified regarding anthropometry and thoracic flexibility. The basis for the updated anthropometry was new data regarding characteristic dimensions and mass distribution collected at a Swedish hospital. Results: In the anthropometry study, 26 children were measured. The main differences between the average of the measured children and the Q3 model were found in the mass distribution of the torso and thighs: the Q3's pelvis was too heavy and the thorax, abdomen/lumbar spine, and thighs were too light. Another difference was identified in the buttock–knee length. Two of the 3 reconstructed crashes had confirmed head impacts. The Q3 model responded with head kinematics that reflected the deduced courses of events for the real children in one of 3 crashes (the one without head impact). The modified Q3 model reflected the real children in 2 of 3 crashes. Conclusions: In high-severity, straight frontal crashes, the Q3 model predicted non-head impact adequately. However, in oblique frontal crashes, the Q3 model did not sufficiently predict the head impacts. The modified Q3 model predicted the head impacts better than the Q3 model did. Greater flexibility of the thorax and redistributed mass made a positive difference regarding the head kinematics.

Conceptual Design of an Automatically Replacing and Charging System for Electric Vehicles

Electric vehicle is an important developing trend of the vehicle industry and the power and technique field. But nowadays, there still exist some problems in this field which cant be solved with mature solutions, such as long time of charging, high cost of replacing and charging station and large areas it covers, low efficiency and so on. By building an effective model, this paper brings up a conceptual design of an automatic system of replacing and charging batteries for electric vehicles with the late-model design of the multi-station device. By observing the effect of the experimental device, it can solve the problems mentioned above, but more should be done to improve it. This design, the demo system, mainly includes electric vehicle model system, replacing and charging station system and GPS navigation system, and it performs excellent in experiment.

Numerical Simulation of Subway Train Vertical Random Vibration Load in Time Domain

It is of importance to identify the subway train random vibration load correctly. On the basis of the in-situ dynamic response measurement, the deterministic data for vertical acceleration of rail were obtained. The problem of identifying the random vibration load of subway train was solved in Matlab, according to the simplified vibration model of vehicle system, and in Newmark-β method. Then the time curve and the amplitude spectrum curve of the vertical random vibration train load were obtained. Compared with Fast Fourier Transform method, Newmark-β method is more simple and practical to simulate the train vertical random vibration load directly in the time domain.

Hunting stability and derailment analysis of a car model of a railway vehicle system

Using a heuristic linear creep model, this article derives the governing differential equations of motion for a vehicle travelling on curved tracks. The vehicle is modelled by a 27-degrees-of-freedom (27-DOF) car system, with lateral and vertical displacement, roll and yaw angle of each wheelset and the bogie frames, as well as lateral displacement, and roll and yaw angle of the car body taken into consideration. To analyse the respective effects of major system parameters on vehicle dynamics, the 27-DOF system is reduced to a 14-DOF system by excluding designated subsets of the system parameters. The effects of suspension parameters of a vehicle on the critical hunting speeds were evaluated by the 14- and 27-DOF systems. The results obtained in this study, show that the critical hunting speeds derived using the 14-DOF system are generally higher than those obtained using the 27-DOF system. Additionally, the critical hunting speeds derived using the heuristic non-linear creep model are lower than those achieved using the linear creep model. The effects on derailment quotients of vehicle speeds are evaluated using both linear and non-linear creep models with various suspension parameters. Finally, the effects of vehicle speed on the derailment quotient for sharp curves and low vehicle speed are investigated and compared with both linear and non-linear creep models.

Coupled Vibration Analysis of Vehicle-Bridge System for Yujiang River Bridge on Nanning-Guangzhou Railway Line

Taking Yujiang River Bridge on Nanning-Guangzhou railway line as study background, the refined numerical simulation model of whole vehicle and whole bridge system for coupled vibration analysis is set up. The dynamic analysis model of the cable-stayed bridge is established by finite element method, and the natural vibration properties of the bridge are analyzed. The German ICE Electric Multiple Unit (EMU) train refined three-dimensional space vehicle model is set up by multi-system dynamics software SIMPACK, and the multiple non-linear properties are considered. The space vibration responses are calculated by co-simulation based on multi-body system dynamics and finite element method when the ICE EMU train passes the long span cable-stayed bridge at different speeds. In order to test if the bridge has the sufficient lateral or vertical rigidity and the operation stability is fine. The calculation results show: The operation safety can be guaranteed, and comfort index is “excellent”. The bridge has sufficient rigidity, and vibration is in good condition.

Test Correlation Framework for Hybrid Electric Vehicle System Model

Test Correlation Framework for Hybrid Electric Vehicle System Model