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Viewing 241 to 270 of 10005
2014-04-01
Technical Paper
2014-01-0876
Barys Shyrokau, Dzmitry Savitski, Danwei Wang
Abstract Nowadays there is a tendency to implement various active vehicle subsystems in a modern vehicle to improve its stability of motion, handling, comfort and other operation characteristics. Since each vehicle subsystem has own limits to generate supporting demand, their potential impact on vehicle dynamics should be analyzed for steady-state and transient vehicle behavior. Moreover, the additional research issue is the assessment of total energy consumption and energy losses, because a stand-alone operation of each vehicle subsystem will provide different impact on vehicle dynamics and they have own energy demands. The vehicle configuration includes (i) friction brake system, (ii) individual-wheel drive electric motors, (iii) wheel steer actuators, (iv) camber angle actuators, (v) dynamic tire pressure system and (vi) actuators generating additional normal forces through external spring, damping and stabilizer forces. A passenger car is investigated using commercial software.
2014-04-01
Technical Paper
2014-01-0874
Edoardo Sabbioni, Federico Cheli, Matteo Riva, Andrea Zorzutti
Abstract For passenger cars, individual tyre model parameters, used in vehicle models able to simulate vehicle handling behavior, are traditionally derived from expensive component indoor laboratory tests as a result of an identification procedure minimizing the error with respect to force and slip measurements. Indoor experiments on agricultural tyres are instead more challenging and thus generally not performed due to tyre size and applied forces. However, the knowledge of their handling characteristics is becoming more and more important since in the next few years, all agricultural vehicles are expected to run on ordinary asphalt roads at a speed of 80km/h.
2014-04-01
Journal Article
2014-01-0870
Guangzhong Xu, Nong Zhang
This paper presents the modeling and characteristic analysis of roll-plane and pitch-plane combined Hydraulically Interconnected Suspension (HIS) system. Vehicle dynamic analysis is carried out with four different configurations for comparison. They are: 1) vehicle with spring-damper only, 2) vehicle with roll-plane HIS, 3) vehicle with pitch-plane HIS and 4) vehicle with roll and pitch combined HIS. The modal analysis shows the unique modes-decoupling property of HIS system. The roll-plane HIS increases roll stiffness only without affecting other modes, and similarly pitch-plane HIS increases the pitch stiffness only with minimum influence on other modes. When roll and pitch plane HIS are integrated, the vehicle ride comfort and handling stability can be improved simultaneously without compromise. A detailed analysis and discussion of the results are provided to conclude the paper.
2014-04-01
Technical Paper
2014-01-0867
Diana Hernandez-Alcantara, Luis Amezquita-Brooks, Ruben Morales-Menendez
Abstract Semi-active suspension systems aim to improve the vehicle safety and comfort. For these systems control laws are required to achieve the desired performance improvements. On the other hand, the instrumentation of the vehicle suspension typically consists only in accelerometers, which are used to measure the vertical accelerations. However, velocities and/or displacements are required to implement the most common control algorithms for semi-active suspension systems. For instance, Skyhook and Groundhook controllers require the knowledge of the suspension vertical velocities. In this article several vertical velocities estimation approaches are studied and compared. In practical applications, it is common to use simple integrators to estimate these variables; nonetheless, it is well known that integrator-based estimations present errors due to drift.
2014-04-01
Technical Paper
2014-01-0865
Yuhang Chen, Yunfeng Ji, Konghui Guo
Abstract In this paper, a sliding mode observer for estimating vehicle slip angle and tire forces is developed. Firstly, the sliding mode observer design approach is presented. A system damping is included in the sliding mode observer to speed the observer convergence and to decrease the observer chattering. Secondly, the sliding mode observer for vehicle states is developed based on a 7 DOF embedded vehicle model with a nonlinear tire model ‘UniTire’. In addition, since the tire lateral stiffness is sensitive to the vertical load, the load transfers are considered in the embedded model with a set of algebraic equations. Finally, a simulation evaluation of the proposed sliding mode observer is conducted on a validated 14 DOF vehicle model. The simulation results show the model outputs closely match the estimations by the proposed sliding mode observer.
2014-04-01
Technical Paper
2014-01-0864
Walid Oraby, Mahmoud Atef Aly, Samir El-demerdash, M. El-Nashar
Abstract Integral Control strategy for vehicle chassis systems had been of great interest for vehicle designers in the last decade. This paper represents the interaction of longitudinal control and lateral control. In other words the traction control system and handling control system. Definitely, tire properties are playing a vital role in such interaction as it is responsible for the generated forces in both directions. A seven degrees of freedom half vehicle model is derived and used to investigate this interaction. The vehicle body is represented as a rigid body with three degrees of freedom, lateral and longitudinal, and yaw motions. The other four degrees are the two rotation motion of the front wheel and the rear wheel. This two motions for each wheel are spin motion and the steering motion. The traction controller is designed to modulate engine torque through adjusting the throttle angle of the engine upon utilized adhesion condition at the driving road wheels.
2014-04-01
Technical Paper
2014-01-0863
Takamasa Shimodaira
Abstract The aim discussed in this paper is to show a technique to predict loads input to the wheels, essential to determining input conditions for evaluation of suspension durability, by means of full vehicle simulations using multi body analysis software Adams/Car. In this process, model environments were built to enable reproduction of driving modes, and a method of reproducing the set-up conditions of a durability test vehicle was developed. As the result of verification of the accuracy of the simulations in the target driving modes, good correlation for waveforms can be confirmed. And also confirm a good correlation in relation to changes of input load due to changes in suspension specifications.
2014-04-01
Technical Paper
2014-01-0861
Axel Gallrein, Manfred Baecker, Michael Burger, Andrey Gizatullin
Abstract In the last two years, Fraunhofer has developed an advanced tire model which is real-time capable. This tire model is designed for ride comfort and durability applications for passenger cars and trucks, as well as for agricultural and construction machines. The model has a flexible belt structure with typically about 150 degrees of freedom and a brush contact formulation. To obtain sufficient computational efficiency and performance for real time, a dedicated numerical implicit time-integration scheme has been developed. Additionally, specific coordinate frames were chosen to efficiently calculate and use the needed Jacobian matrices. Independently from this, Fraunhofer ITWM has developed and installed the new driving simulator RODOS (RObot based Driving and Operation Simulator), which is based on the industrial robot KUKA KR1000.
2014-04-01
Technical Paper
2014-01-0885
Mustafa Ali Arat, Saied Taheri
Abstract A vehicle's response is predominately defined by the tire characteristics as they constitute the only contact between the vehicle and the road; and the surface friction condition is the primary attribute that determines these characteristics. The friction coefficient is not directly measurable through any sensor attachments in production-line vehicles. Therefore, current chassis control systems make use of various estimation methods to approximate a value. However a significant challenge is that these schemes require a certain level of perturbation (i.e. excitation by means of braking or traction) from the initial conditions to converge to the expected values; which might not be the case all the time during a regular drive.
2014-04-01
Technical Paper
2014-01-0883
Wenku Shi, Changxin Wang
Abstract In order to reasonably match the variable stiffness suspension and optimize the ride comfort and stability of a light bus, a virtual prototype model of the light bus was established in Adams-Car. Before the optimization, the tyre mechanical characteristics were tested by using a plate-type tyre tester, then the magic formula model of the tyre (Pac2002) was obtained by means of the global parameter identification method. The vertical vibration of the virtual model was simulated with the simulated B-class road profile, and its handling stability performance was also studied by simulation of the pylon course slalom test and steady static circular test. After that, an optimal method of the variable stiffness suspension was put forward. In the proposed method, the two-level stiffness (k1, k2) and the damping of the rear suspension and the torsional stiffness of the pre and post stabilizer bars were taken as the optimal variables.
2014-04-01
Technical Paper
2014-01-0878
Adam C. Reid, David Philipps, Fredrik Oijer, Inge Johansson, Moustafa EL-Gindy
Abstract The rigid-ring tire model is a simplified tire model that describes a tire's behaviour under known conditions through various in-plane and out-of-plane parameters. The complex structure of the tire model is simplified into a spring-mass-damper system and can have its behaviour parameterized using principles of mechanical vibrations. By designing non-linear simulations of the tire model in specific situations, these parameters can be determined. They include, but are not limited to, the cornering stiffness, vertical damping constants, self-aligning torque stiffness and relaxation length. In addition, off-road parameters can be determined using similar methods to parameterize the tire model's behaviour in soft soils. By using Finite Element Analysis (FEA) modeling methods, validated soil models are introduced to the simulations to find additional soft soil parameters.
2014-04-01
Journal Article
2014-01-0816
Massimiliano Gobbi, Giampiero Mastinu, Giorgio Previati, Mario Pennati
The measurement of the contact forces between road and tires is of fundamental importance while designing road vehicles. In this paper, the design and the employment of measuring wheels for trucks and heavy vehicles is presented. The measuring wheels have been optimized in order to obtain high stiffness and the approximately the same mass of the wheels normally employed. The proposed multicomponent measuring wheels are high- accuracy instruments for measuring the dynamic loads during handling and durability testing. The measuring wheels can replace the wheels of the truck under normal operation. Such family of wheels plays a major role in modern road vehicles development. The measuring wheel concept design is based on a patented three-spoke structure connected to the wheel rim. The spokes are instrumented by means of strain gauges and the measuring wheel is able to measure the three forces and the three moments acting at the interface between the tire and the road.
2014-04-01
Journal Article
2014-01-0721
Zeyu Ma, Jinglai Wu, Yunqing Zhang, Ming Jiang
In this paper, a new computational method is provided to identify the uncertain parameters of Load Sensing Proportional Valve (LSPV) in a heavy truck brake system by using the polynomial chaos theory. The simulation model of LSPV is built in the software AMESim depending on structure of the valve, and the estimation process is implemented relying on the experimental measurements by pneumatic bench test. With the polynomial chaos expansion carried out by collocation method, the output observation function of the nonlinear pneumatic model can be transformed into a linear and time-invariant form, and the general recursive functions based on Newton method can therefore be reformulated to fit for the computer programming and calculation. To improve the estimation accuracy, the Newton method is modified with reference to Simulated Annealing algorithm by introducing the Metropolis Principle to control the fluctuation during the estimation process and escape from the local minima.
2014-04-01
Technical Paper
2014-01-0847
Andrew Hall, John McPhee
Abstract Physical rig testing of a vehicle is often undertaken to obtain experimental data that can be used to ensure a mathematical model is an accurate representation of the vehicle under study. Kinematics and Compliance (K&C) testing is often used for this purpose. The relationship between the hard point locations and compliance parameters, and K&C characteristics of a suspension system is complex, and so automating the process to correlate the model to the test data can make the exercise easier, faster and more accurate than hand tuning the model. In this work, such a process is developed. First, the model parameters are adjusted, next a simulation is run, before the results are read and post processed. This automation processed is used in conjunction with an optimization procedure to carry out the K&C correlation.
2014-04-01
Technical Paper
2014-01-0848
Dongmei Wu, Haitao Ding, Konghui Guo, Zhiqiang Wang
Abstract Pressure following control is the basic function of Electro-Hydraulic Braking system (EHB), which is also the key technology of stability control system and regenerative braking system for hybrid and electric vehicles. Experimental research is an important method for the control and application of EHB. This paper describes a method to test and control the EHB system through experiment on the Hardware-in-the-loop (HIL) test bench and wheel motor electric vehicle. First, the HIL test bench was established, in which the EHB was tested, including the characteristics of solenoid valves and motor. Then the wheel cylinder pressure was controlled to follow the specific signal input and the master cylinder pressure. Based on this, EHB and the pressure following control method were applied to the wheel motor electric vehicle. The results show that the braking pressure can follow the driver's braking intention to realize the conventional braking function of electric vehicles.
2014-04-01
Technical Paper
2014-01-0849
Xinxin Shao
Abstract In this paper, a passive anti-pitch anti-roll hydraulically interconnected suspension is proposed for compromising the control between the pitch and roll mode of the sprung mass. It has the advantage in improving the directional stability and handling quality of vehicles during steering and braking manoeuvres. Frequency domain analysis of a 7-DOF full-car model with the proposed system is presented. The modeling of mechanical subsystem is established based on the Newton's second law. Then the mechanical-hydraulic system boundary conditions are developed by incorporating the hydraulic strut forces into the mechanical subsystem as externally applied forces. The hydraulic subsystem is modelled by using the impedance method, and each circuit are determined by the transfer matrix method. And then the modal analysis method is employed to perform the vibration analysis between the vehicle with the conventional suspension and the proposed HIS.
2014-04-01
Technical Paper
2014-01-0859
Haizhen Liu, Weiwen Deng, Changfu Zong, Jian Wu
Abstract This paper first presents an algorithm to detect tire blowout based on wheel speed sensor signals, which either reduces the cost for a TPMS or provides a backup in case it fails, and a tire blowout model considering different tire pressure is also built based on the UniTire model. The vehicle dynamic model uses commercial software CarSim. After detecting tire blowout, the active braking control, based on a 2DOF reference model, determines an optimal correcting yaw moment and the braking forces that slow down and stop the vehicle, based on a linear quadratic regulator. Then the braking force commands are further translated into target pressure command for each wheel cylinder to ensure the target braking forces are generated. Some simulations are conducted to verify the active control strategy.
2014-04-01
Journal Article
2014-01-0846
Ankang Jin, Weiguo Zhang, Shihu Wang, Yu Yang, Yunqing Zhang
The suspension system of a heavy truck's driver seat plays an important role to reduce the vibrations transmitted to the seat occupant from the cab floor. Air-spring is widely used in the seat suspension system, for the reason that its spring rate is variable and it can make the seat suspension system keep constant ‘tuned’ frequency compared to the conventional coil spring. In this paper, vibration differential equation of air-spring system with auxiliary volume is derived, according to the theory of thermodynamic, hydrodynamics. The deformation-load static characteristic curves of air-spring is obtained, by using a numerical solution method. Then, the ADAMS model of the heavy truck's driver seat suspension system is built up, based on the structure of the seat and parameters of the air-spring and the shock-absorber. At last, the model is validated by comparing the simulation results and the test results, considering the seat acceleration PSD and RMS value.
2014-04-01
Technical Paper
2014-01-0763
Suhas Kangde, Vishal Shitole, Ashish Kumar Sahu
Abstract Automotive Suspension is one of the critical system in load transfer from road to Chassis or BIW. Using flex bodies in Multi body simulations helps to extract dynamic strain variation. This paper highlights how the MBD and FE integration helped for accurate strain prediction on suspension components. Overall method was validated through testing. Good strain correlation was observed in dynamic strains of constant amplitude in different loading conditions. Combination of different direction loading was also tested and correlated. Method developed can be used in the initial phase of the vehicle development program for suspension strength evaluation. Suspension is one of the important system in vehicle which is subjected to very high loading in all the directions. To predict the dynamic stresses coming on the suspension system due to transient loads, faster and accurate method is required.
2014-04-01
Journal Article
2014-01-0803
Tau Tyan, Jeff Vinton, Eric Beckhold, Xiangtong Zhang, Jeffrey Rupp, Nand Kochhar, Saeed Barbat
This paper presents the final phase of a study to develop the modeling methodology for an advanced steering assembly with a safety-enhanced steering wheel and an adaptive energy absorbing steering column. For passenger cars built before the 1960s, the steering column was designed to control vehicle direction with a simple rigid rod. In severe frontal crashes, this type of design would often be displaced rearward toward the driver due to front-end crush of the vehicle. Consequently, collapsible, detachable, and other energy absorbing steering columns emerged to address this type of kinematics. These safety-enhanced steering columns allow frontal impact energy to be absorbed by collapsing or breaking the steering columns, thus reducing the potential for rearward column movement in severe crashes.
2014-04-01
Technical Paper
2014-01-0714
Sanghun Cho, Taewan Gu, Eunyoung Yoo, Youngkyu Jeong, Baegsu Joo
Abstract In automotive software developments, since the types of software functionalities are depending on automotive engineering domains such as powertrain, body, and chassis, software logic and data processing, code complexity, and its reliability are also depending on them. Therefore, it has some challenges that monolithic code quality measures are applied to software code for all domains. In addition, imprecise criteria for the measures also can make software developers and testers confused whether their code verifications are enough or not. This paper proposes domain-specific code quality measures and precise criteria by combining a new functionality model, named Abstract Function Model (AFM), and shows results of automotive software functionality analysis using the model. Using 8 real automotive software projects, we derived statistics of software code on specific automotive engineering domain and identified code quality measures from the statistics.
2014-04-01
Technical Paper
2014-01-0057
Akihito Yamamoto, Haruhiko Sugai, Ryo Kanda, Shuuichi Buma
Abstract This paper reports the results of a study into a preview control that uses the displacement of the road surface in front of the vehicle to improve for front and rear actuator responsiveness delays, as well as delays due to calculation, communication, and the like. This study also examined the effect of a preview control using the eActive3 electric active suspension system, which is capable of controlling the roll, pitch, and warp modes of vehicle motion.
2014-04-01
Technical Paper
2014-01-0051
Gang Tang, Jinning Li, Chao Ding, Yunqing Zhang
Abstract This paper describes a simplified model to identify sprung mass using golden section method, the model treats the unsprung mass vertical acceleration as input and the sprung mass vertical acceleration as output, which can avoid the nonlinear influence of trye. Unsprung mass can be also calculated by axle load and the identified sprung mass. This study carries out road test on the vehicle ride comfort and takes a scheme that the group of 20 km/h is used to identify sprung mass and the group of 80 km/h is used to verify the identification result. The similarity of the results from the simulation and experiments performed are, for the sprung mass, 98.59%. A conclusion can be drawn that the simple method to measure the sprung mass in the suspension systems in used vehicles, such as the vehicle shown here, is useful, simple and has sufficient precision.
2014-04-01
Journal Article
2014-01-0295
Zeyu Ma, Jinglai Wu, Yunqing Zhang, Ming Jiang
The main purpose of this research is to investigate the optimal design of pipeline diameter in an air brake system in order to reduce the response time for driving safety using DOE (Design of Experiment) method. To achieve this purpose, this paper presents the development and validation of a computer-aided analytical dynamic model of a pneumatic brake system in commercial vehicles. The brake system includes the subsystems for brake pedal, treadle valve, quick release valve, load sensing proportional valve and brake chamber, and the simulation models for individual components of the brake system are established within the multi-domain physical modeling software- AMESim based on the logic structure. An experimental test bench was set up by connecting each component with the nylon pipelines based on the actual layout of the 4×2 commercial vehicle air brake system.
2014-04-01
Technical Paper
2014-01-0277
Chi Jin, Lu Xiong, Zhuoping Yu, Yuan Feng
Abstract In this paper we present a path following control design for a six-wheel skid-steering vehicle. Contrary to the common approaches that impose non-holonomic constraints, a dynamic vehicle model is established based on a pseudo-static tire model, which uses tire slip to determine tire forces. Our control system admits a modular structure, where a motion controller computes the reference vehicle yaw rate and reference vehicle speed and a dynamics controller tracks these signals. A robust nonlinear control law is designed to track the reference wheel speeds determined by the dynamics controller with proved stability properties. Saturated control techniques are employed in designing the reference yaw rate, which ensures the magnitude of the reference yaw rate does not violate the constraint from the ground-tire adhesion. The simulation results demonstrate the effectiveness of the proposed path following control design.
2014-04-01
Technical Paper
2014-01-0271
Hu Zhang, JianWei Zhang, Konghui Guo
Abstract Whether high-precision torque control or motor condition monitoring need accurate motor parameters. For the three parameters of surface-mounted permanent magnet synchronous motor (SPMSM), the voltage equation is rank-deficient. To solve this problem, some scholars proposed methods that build full rank equations with signal injection, but this will produce motor torque ripple, which is not suitable for application to the EPS. Therefore, this paper proposes a method based on MRAS to identify motor parameters step by step. The proposed two steps identification method can make the reference model full rank in every step, but the total decoupling between parameters identification processes cannot be realized for the assumption that the prior step result is the real value. It was found in experiment that this effect varies with the motor operating conditions.
2014-04-01
Technical Paper
2014-01-0267
Zhiting Zhu, Lu Xiong, Chi Jin
Abstract The control in transient conditions when hydraulic brake and regenerative brake switch mutually is the key technical issue about electric vehicle hybrid brake system, which has a direct influence on the braking feel of driver and vehicle braking comfort. A coordination control system has been proposed, including brake force distribution correction module and motor force compensation module. Brake force distribution correction module has fixed the distribution results in hydraulic brake force intervention condition, hydraulic brake force evacuation condition and regenerative brake force low speed evacuation condition. Motor compensation module has compensated hydraulic system with motor system, which has fast and accurate response, thus the response of whole hybrid system has been improved.
2014-04-01
Technical Paper
2014-01-0243
Lijiao Yu, Hongyu Zheng, Changfu Zong
Abstract Nowadays, conventional steering system cannot meet consumers' requirements as their environmental awareness increasing. Electrically controlled steering system can solve this problem well [1] [2]. Electrically controlled steering system has been not only applied widely in automobile steering technique but also becomes an important section of automobile integrated chassis control technology. It is necessary for vehicles to test their every component repeatedly before every component assembled. So a test bench becomes an essential part for vehicle products' design and improvement. The electrically controlled steering system consists of Electric Power Steering system (EPS), Active Front Steering (AFS) and Steer by Wire (SBW). The similarity among them is containing pinion-and-rack mechanical structure, so it is viable to design a test bench suitable for these three systems. This paper takes EPS as a prototype to verify the design's availability.
2014-04-01
Technical Paper
2014-01-0411
Yuan Qu, Wang Hongbin, Dechao Zhang, Linbo Zhang, Shen Wu
Abstract The understeer of vehicle is desired for the vehicle's handling performance, and the roll rate of rear suspension is one of the key characteristics to achieve the understeer performance. A proper roll rate of the rear suspension is required to assure a certain level of understeer. Generally, in the vehicle dynamic tuning process, several methods are available for improving understeer performance, e.g., changing the hard-points of suspensions, adjusting stiffness of bushings, etc. On the other hand, structure optimization of components can be used in some case to improve the performance. In this paper, the optimization method is applied to the twist beam of rear suspension. The change in local geometry by optimized design leads to appropriate adjustment of the roll rate. Finally the vehicle understeer performance reaches design target.
2014-04-01
Technical Paper
2014-01-0394
Yong-Sub Yi, Joonhong Park, Kyung-Jin Hong
Abstract In the early stage of vehicle development process, it is customary to establish a set of goals for each kinematic and compliance (K&C) characteristic and try to find out design variables such as the location of hard points and bushing stiffness which can achieve these goals. However, since it is very difficult to find out adequate set of design variables which satisfy all the goals, many engineers should rely on their own experiences and intuitions, or repeat trial and error to design a new suspension and improve old one. In this research, we develop a suspension design process by which suspension K&C characteristic targets can be achieved systemically and automatically. For this purpose, design optimization schemes such as design of experiments (DoE) and gradient-based local optimization algorithm are adopted.
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