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2017-03-28
Technical Paper
2017-01-1494
Weinan Tao, Bingzhao Gao, Hongqing Chu, Mengjian Tian, Hong Chen
Steer-by-wire technology is considered as a next step in steering system evolution. The substitution of electronic systems in place of mechanical components simplifies the car interior design and saves larger space for driver cabin. But the absence of the force coming from the road directly challenges us to model an optimal steering feel. Referring to the structure of the conventional steering systems, the forces transmitted to the driver through handwheel consist of steering system friction and aligning torque. In the paper, the steering system friction is simulated by the Stribeck friction model. The accurate friction model is important for simulating feedback torque during stand-still, low speed and low lateral acceleration conditions. Besides that, the elasticity of steering column should be taken into consideration, which helps to improve the dynamic response performance of the system especially in the condition that the steering angle changes rapidly.
2017-03-28
Technical Paper
2017-01-1555
Mirosław Jan Gidlewski, Krystof JANKOWSKI, Andrzej MUSZYŃSKI, Dariusz ŻARDECKI
Lane change automation appears to be a fundamental problem of vehicle automated control, especially when the vehicle is driven at high speed. Selected relevant parts of the recent research project are reported in this paper, including literature review, the developed models and control systems, as well as crucial simulation results. In the project, two original models describing the dynamics of the controlled motion of the vehicle were used, verified during the road tests and in the laboratory environment. The first model – fully developed (multi-mass, 3D, nonlinear) – was used in simulations as a virtual plant to be controlled. The second model – a simplified reference model of the lateral dynamics of the vehicle (single-mass, 2D, linearized) – formed the basis for theoretical analysis, including the synthesis of the algorithm for automatic control. That algorithm was based on the optimal control theory.
2017-03-28
Technical Paper
2017-01-1585
Renxie Zhang, Lu Xiong, Zhuoping Yu, Wei Liu
A dynamic controller is designed for unmanned skid-steering vehicle, which runs in complex road condition all the time. The vehicle speed is controlled through engine driving torque to achieve the desired vehicle speed and the steering is controlled through hydraulic braking on each side of the vehicle to achieve the desired yaw rate. Due to the complexity in wheel-ground interaction, the tire slip cannot be ignored. Besides, it may result in the saturation of the actuators torque, which will further cause the instability of the skid-steering vehicle. Therefore, contrary to the common approaches considering non-holonomic constraints, tire slip and saturation of actuators torque influencing the driving and braking are considered based on the analysis of vehicle dynamic model and nonlinear tire model. With conditional integrators, a dynamic controller overcoming integral saturation is designed under influence of tire forces and constraint of actuators.
2017-03-28
Technical Paper
2017-01-1560
Wei Liu, Lu Xiong, Bo Leng, Haolan Meng, Renxie Zhang
In this paper, a novel method based on the sideslip angle-yaw rate phase plane is proposed to establish the vehicle stability criterion for vehicle stability control. Firstly, a nonlinear two degrees of freedom vehicle dynamic model is established by adopting the Magic Formula of nonlinear tire model. Then, an equilibrium point solution approach is introduced. Next, according to the model in MATLAB/Simulink, the sideslip angle-yaw rate phase plane is gained. Emphatically, the effects of different driving conditions (the front wheel angle, road friction coefficient and vehicle speed) on the stability boundary on the phase plane are analyzed. According to the topological analysis based on the equilibrium point, the stability regions under different driving conditions can be divided into two types: curve type and diamond type. The judgment method for the type of stability region to which the phase plane corresponds is put forward according to real-time driving conditions.
2017-03-28
Technical Paper
2017-01-1562
Junyu Zhou, Chao Liu, Jan Kubenz, Günther Prokop
This Paper describes a new hybrid algorithm for multi-body Dynamics in vehicle system dynamics which exploits the advantages of both embedding technique algorithm and augmented formulation algorithm. A vehicle dynamic modeling based on the hybrid algorithm is presented. Embedding technique has a relatively small number of equations of motion. Using embedding technique an enhanced parametric vehicle dynamics model can be built, in which the kinematic and compliance characteristics of suspension are represented by characteristic curves. Because of small number of equations the vehicle dynamics model can be simulated very efficiently. Compare to embedding technique a main benefit of augmented formulation is relatively simple for computer programming. With the help of the augmented formulation the structure of the vehicle dynamic model can easily be extended. Advantages of both embedding technique and augmented formulation can be utilized by hybridizing them.
2017-03-28
Technical Paper
2017-01-1561
Anton A. Tkachev, Nong Zhang
Rollover prevention is one of the prominent priorities in vehicle safety and handling control. A promising alternative for roll angle cancellation is the active hydraulically interconnected suspension. This paper represents the analytical model of active hydraulically interconnected suspension system followed by the general simulation. Passive hydraulically interconnected suspension systems have been widely discussed and studied up to now. This work specifically focuses on the active hydraulically interconnected suspension system. Equations of motion of the system are formalised first. The entire system consists of two separate systems that can be modelled independently and further combined together for simulation. One of the two systems is 4 degrees of freedom half-car model which simulates vehicle lateral dynamics and vehicle roll angle response to lateral acceleration in particular.
2017-03-28
Technical Paper
2017-01-1537
Ananya Bhardwaj
Improving brake cooling has commanded substantial research in the automotive sector, as safety remains paramount in vehicles of which brakes are a crucial component. To prevent problems like brake fade and brake judder, heat dissipation should be maximized from the brakes to limit increasing temperatures. This research is a CFD investigation into the impact of existing wheel center designs on brake cooling through increased cross flow through the wheel. The novel study brings together the complete wheel and disc geometries in a single CFD study and directly measures the effect on brake cooling, by implementing more accurately modelled boundary conditions like moving ground to exactly replicate true conditions. It also quantifies the improvement in cooling rate of the brake disc with change in wheel design unlike previous studies. The axial flow discharge was found to be increased to 0.47 m3/min for the suggested design in comparison to 0.04 m3/min for traditional design.
2017-03-28
Technical Paper
2017-01-1590
Jyotishman Ghosh, Stéphane Foulard, Rafael Fietzek
The knowledge of vehicle mass is very important for the proper functioning of various vehicle stability control systems and vehicle state observers. A method for estimating the vehicle mass in real time is presented. Traditional mass estimation methods suffer due the lack of the knowledge of vehicle parameters, road surface conditions and most importantly the effect of the vehicle transmission. To resolve these issues, a vehicle model independent method is utilized in conjunction with a drivetrain torque output observer to obtain the estimate of the vehicle mass. Simulations and experimental track tests indicate that the method is able to accurately estimate the vehicle mass with a relatively fast rate of convergence compared to traditional methods.
2017-03-28
Technical Paper
2017-01-1225
Jayaraman Krishnasamy, Martin Hosek
An advanced electric motor with hybrid-field topology has been developed for automotive traction applications. Departing from the conventional radial- and axial-field designs, the hybrid-field motor features three-dimensional magnetic flux paths in a geometry that maximizes the effective volume for magnetic flux flow. The three-dimensional flux paths are enabled by an isotropic soft magnetic material, which has been engineered to replace conventional laminated winding cores with solid isotropic components. The material is produced by a novel additive-manufacturing process based on spray forming. The paper introduces the spray-forming process for motor stator components and presents a conceptual design of the traction motor developed around them, including the motor topology, stator construction and rotor construction. The stator features a spray-formed core with three-dimensional magnetic flux paths, high-density windings and direct liquid cooling.
2017-03-28
Technical Paper
2017-01-0084
Jiantao Wang, Bo Yang, Jialiang Liu, Kangping Ji, Qilu Wang
Studies show that driving in foggy environment is a security risk, and when driving in foggy environment, the drivers are easy to accelerate unconsciously. The safety information prompted to the driver is mainly from fog lights, road warning signs and the traffic radio. In order to increase the quality of the safety tips to prevent drivers from unintended acceleration and ensure the security of driving in foggy environment, the study proposes a safety speed assessment method for driving in foggy environment, combining the information of driving environment, vehicle’s speed and the multimedia system.The method uses camera which is installed on the front windshield pillar to collect the image about the environment, and uses the dark channel prior theory to calculate the visibility. And by using the environment visibility, the safety speed can be calculated based on the kinematics theory. And it is appropriate for vehicles which have different braking performance.
2017-03-28
Technical Paper
2017-01-1113
Yulong Lei, Pengxiang Song, Hongpeng Zheng, Yao Fu, Zhenjie Liu, Xuanyi Fu
Hydraulic retarders have been widely used in heavy-duty vehicles because of its advantages such as large braking torque and long operating hours. They can be used instead of service brakes in non-emergency braking conditions and can also reduce frequency and time of driver’s actions in braking process, thereby minimizing heat-related problems. In order to accurately produce braking torque needed for the vehicle in time by using hydraulic retarder, which enable the vehicle to travel stably and safely during downhill driving, aiming at the constant-speed function of hydraulic retarder, the research of constant speed control method is conducted in this paper. The structure and working principle of hydraulic retarder is introduced and the dynamic characteristic is analyzed. And the theoretical model of vehicle and hydraulic retarder are established based on dynamic analysis of the vehicle downhill driving.
2017-03-28
Technical Paper
2017-01-1575
Andrei Keller, Sergei Aliukov, Vladislav Anchukov
Trucks are one of the most common modes of transport and they are operated in various road conditions. As a rule, all-wheel drive trucks are equipped with special systems and mechanisms to improve their cross-country capability and overall efficiency. The usage of blocked mechanisms for power distribution is one of the most popular and effective ways to improve the off-road vehicle performance. However, the lock of differential may adversely affect the stability and control of vehicle because of the unobvious redistribution of reactions acting on wheels, which consequently leads to poor performance and safety properties. Problems of rational distribution of power in transmissions of all-wheel drive vehicles, as well as research in the field of improving directional stability and active safety systems are among the priorities in modern automotive industry.
2017-03-28
Technical Paper
2017-01-0348
Mani Shankar, I V N Sri Harsha, K V Sunil, Ramsai Ramachandran
In an automobile, road loads due to tire-road interaction are transferred to vehicle body through suspension. This makes suspension a critical component from the body durability perspective. During vehicle design and development, optimization of suspension parameters to suit ride and handling performance is a continuous and iterative process. These changes on suspension can affect vehicle body durability performance. This paper tries to establish a process to evaluate the effect of changes in suspension parameters on body durability, thus helping in understanding the impact of these changes. The process starts with virtual model building in Multi Body Dynamics software. The base line model is co-related with testing using responses like spring displacement at suspension, acceleration and strain data at the vehicle body.
2017-03-28
Technical Paper
2017-01-1556
Jianbo Lu, Li Xu, Daniel Eisele, Stephen Samuel, Matthew Rupp, Levasseur Tellis
The paper presents an advanced yaw stability control (AYSC) system that uses a centralized inertial measurement unit (IMU) to measure the 6 DOF motions of a vehicle and uses the enhanced vehicle states to improve the effectiveness of the traditional electronic stability control (ESC) systems. The MEMS based IMU has nowadays been widely used in consumer electronics, such as smart phones, and its cost has been significantly reduced, which makes it feasible to roll out IMU for ESC type of systems. The additional info from an IMU helps improve the sensing capability of a vehicle, which in turn leads to refined stability control commands for AYSC such that the better control performance than the traditional ESC can be achieved (w.r.t. the real world driving scenarios). Vehicle tests will be used to show the improved control performance.
2017-03-28
Technical Paper
2017-01-0056
Naveen Mohan, Martin Törngren, Sagar Behere
With the advent of ISO 26262 there is an increased emphasis on top-down design in the automotive industry. While the standard delivers a best practice framework and a reference safety lifecycle, it lacks detailed requirements for its various constituent phases. The lack of guidance becomes especially evident for the reuse of legacy components and subsystems, the most common scenario in the cost-sensitive automotive domain, leaving vehicle architects and safety engineers to rely on experience without methodological support for their decisions. This poses particular challenges in the industry which is currently undergoing many significant changes due to new features like connectivity, servitization, electrification and automation. In this paper we focus on automated driving where multiple subsystems, both new and legacy, need to coordinate to realize a safety-critical function.
2017-03-28
Technical Paper
2017-01-0108
Zaydounr Y. Rawashdeh, Trong-Duy Nguyen, Anoop Pottammal, Rajesh Malhan
In this work, DSRC capabilities combined with autonomous vehicles' on-board sensors (camera) are used to trigger an Automated Emergency Brake (AEB) for urban traffic light intersection scenario. The system is designed to achieve AEB in two phases, the comfortable brake and the full stop emergency brake. The comfortable brake is applied first based on the content of the Signal Phase and Timing (SPaT) / Map data (MAP) messages received from the Road Side Unit (RSU) at larger distances. And, once the traffic light becomes in the detection field of view of the camera, the output of the camera-based Traffic Light Detection (TLD) and recognition software is fused with the SPaT/MAP content to decide on triggering the full stop emergency brake. On the automated vehicle, the content of the received SPaT/MAP is parsed and communicated through UDP packets to the central processing unit that runs the camera-based TLD software for traffic light state matching and distance calculation.
2017-03-28
Technical Paper
2017-01-0145
Edward Palmer, Wilko Jansen
The primary function of the brake system is to convert the kinetic energy of the vehicle to heat which is then dissipated to the environment. The performance characteristics of many of the components within the brake system are temperature dependant; with numerous issues associated with excessive temperatures such as vaporisation of the brake fluid, degradation of the friction coefficient at the disc to pad interface, thermo-mechanical deformation of the brake rotor, excessive wear and numerous NVH problems. Therefore it is clear that in order to avoid the customer encountering these failure modes the brakes must be specified with sufficient thermal inertia and cooling for the intended vehicle and drive cycle. This paper presents a high fidelity CAE technique for predicting the temperature of the front brake and the surrounding suspension components whilst installed on vehicle.
2017-03-28
Technical Paper
2017-01-0413
Mustafa Ali Arat, Emmanuel Bolarinwa
Most ground vehicles related accidents occur when the friction demand to perform a maneuver with a certain vehicle and tires exceeds the coefficient of friction of the pavement surface. As generally known, the forces and moments acting on the vehicle body are mainly generated by tire forces which highly depend on this surface friction coefficient. The common characteristics of tire forces on any surface include a linear region where the forces vary linearly with respect to the relative slip values; and a nonlinear region where the forces saturate and may even start decreasing. The experience of most of the daily drivers on the roads is limited within this linear region where the dynamic behavior of the vehicle remains proportional to the driver’s inputs. Therefore, an unexpected change in tire or surface characteristics (due to a change in surface friction, large driver inputs, etc.) may easily cause the driver to panic and/or to lose his/her ability to maintain a stable vehicle.
2017-03-28
Technical Paper
2017-01-1408
Satoshi Kozai, Yoshihiko Takahashi, Akihiro Kida, Takayuki Hiromitsu, Shinji Kitaura, Sadamasa Sawada, Gladys Acervo, Marius Ichim
The goal of both automakers and vehicle users is to minimize the negative impacts of vehicles on society, such as traffic accidents, not only on the road but parking area, optimizing the enjoyment of using a car, comfort, and usability. To realize this, we have already provided automatic brake system (ICS) for static obstacles in parking area. We have also developed the Rear Cross Traffic Auto Brake (RCTAB) system, which detects a vehicle approaching from the sides when backing out of a parking area. We decided RCTAB system specifications based on two information “Approaching vehicle speed in parking area” and “Maximum backing speed”. RCTAB system structure consists of Radar which shared with “Blind Spot Monitor” and ECU which shared with “ICS Computer”. The radar detects the approaching vehicle. The ICS Computer judge Collision prediction and request “Braking Force” and “Driving Force” to Brake and Engine Computer.
2017-03-28
Technical Paper
2017-01-1505
Andreas Hackl, Wolfgang Hirschberg, Cornelia Lex, Georg Rill
With increasing level of complexity and automation in the area of automotive engineering, the simulation of safety relevant Advanced Driver Assistance Systems (DAS) leads to increasing accuracy demands in the description of tyre contact forces. This includes the consideration of dynamic effects, such as the delayed reaction in longitudinal and lateral tyre forces to dynamic changes of slip in the tyre road contact patch. Often, this behaviour is characterized by a first-order differential equation which describes the deflection of particles in the tire’s tread by considering a spring and a damper element in parallel, also known as Kelvin-Voigt model. Based on previous investigations the proposed article deals with the experimental validation of the first-order Kelvin-Voigt model based on measurement data from an industrial flat track test bench. First investigations showed that for selected operational points, these simple models show good compliance.
2017-03-28
Technical Paper
2017-01-0454
Colin Young
Contacts between different meshed components in a finite element model frequently present modeling challenges. Tracking the progress of contact and separation is computationally expensive and may result in non-convergence of the model. In many contact problems of practical interest, such as bolted assemblies or in a shaft bearing where the shaft is constrained against rotation, it is clear that the components are in essentially constant contact and relative motion between them is negligible. In these cases, we can reduce the computational burden by defining an interface between the bodies using modeling devices other than the contact commands. Some approaches in common use, such as tying the meshed surfaces together, while they resolve convergence issue, can result in non-physical stress distributions and un-conservative results in some cases.
2017-03-28
Technical Paper
2017-01-1405
Tzu-Sung Wu
Autonomous Emergency Braking Systems (AEBS) usually contain radar, (stereo) camera and/or LiDAR-based technology to identify potential collision partners ahead of the car, such that to warn the driver or automatically brake to avoid or mitigate a crash. The advantage of camera is less cost: however, is inevitable to face the defects of cameras in AEBS, that is, the image recognition cannot perform good accuracy in the poor or over-exposure light condition. Therefore, the compensation of other sensors is of importance. Motivated by the improvement of false detection, we propose a Pedestrian-and-Vehicle Recognition (PVR) algorithm based on radar to apply to AEBS. The PVR employs the radar cross section (RCS) and standard deviation of width of obstacle to determine whether a threshold value of RCS and standard deviation of width of the pedestrian and vehicle is crossed, and to identity that the objective is a pedestrian or vehicle, respectively.
2017-03-28
Technical Paper
2017-01-1427
Daniel Koch, Gray Beauchamp, David Pentecost
Tire disablement events can cause a drag force that slows a vehicle’s speed. In this study, the magnitude of the deceleration was measured in 29 high speed tread separation and air loss tests. The tires tested were circumferentially cut to create partial and full tread separations, or prepared to lose air rapidly. The deceleration rates were corrected for the slope of the road, aerodynamic drag and rolling resistance of each vehicle tested. These deceleration rates can assist in reconstructing the speed of a vehicle involved in an accident following a tire disablement.
2017-03-28
Technical Paper
2017-01-1591
Haotian Cao, Xiaolin Song, Zhi Huang
Generally, lateral steering control which ensures good performance of the tracking quality and handling quality simultaneously for autonomous vehicle in high speed is a changeling task. In order to keep the vehicle safe when faces a situation with an emergency lane change, a switched MPC lateral steering controller which is on the basis of the stability characteristic of the vehicle is presented in this paper. First, a MPC steering controller based on the 3DOF nonlinear vehicle model is derived, a comparative study of different vehicle models for MPC control are conducted to prove that the presented MPC steering controller with 3DOF nonlinear vehicle model possesses an advantage of balancing the conflicts between the tracking quality and handling quality. Further, a performance evaluation system which assesses the vehicle handling quality and tracking quality is established.
2017-03-28
Technical Paper
2017-01-1567
Jaepoong Lee, Sehyun Chang, Kwangil Kim, Bongchoon Jang, Dongpil Lee, Byungrim Lee, Kyongsu Yi
This paper proposes a reference steering wheel torque map and a torque tracking algorithm via steer-by-wire to design the targeted steering feel. The reference steering wheel torque map is designed using the measurement data of rack force and steering characteristic of a target performance of the vehicle at sinusoidal and transition steering test. Since the target performance of the vehicle is only tested in nominal road condition, various road conditions such as disturbances and tire-road friction are not considered. Hence, the measurement data of the rack force of reflecting the road conditions in the reference steering wheel torque map have been used. The rack force is the net force which consists of tire aligning moment, road friction force and normal force on the tire kingpin axis. A motor and a magnetorheological damper are used as actuators to generate the desired steering feel using the torque tracking algorithm.
2017-03-28
Technical Paper
2017-01-1579
Liang-kuang Chen, Chien-An Chen
The electric buses have gained more popularity aiming to reduce pollutions due to transportation. Equipping the electric buses with four independent driving motors leads to the utilizations of smaller motors, which generally implies lower cost. Additionally, it also opens up the possibility of implementing direct yaw moment control (DYC) for the electric buses. While DYC has been widely used to improve yaw plane stability, its usage has to be limited since the differential torque inevitably increases the loadings on the lateral tire force which may increase the risk of instability. Four wheel steering (4WS), on the other hand, has the capability to mitigate the vehicle understeer or oversteer situations. However, since the yaw rate response is immediately affected by the additional rear wheel steering, it is usually used only in critical situations with limited amount of control so that the yaw rate will not quickly deviate from the desired value based on the roadway curvature.
2017-03-28
Technical Paper
2017-01-1580
Smitha Vempaty, Yuping He
This paper reviews the state-of-the art approaches for car-trailer lateral stability control. Ensuring the lateral stability and handling of a car-and-trailer combination remains one of the challenges in active safety system design and development for articulated vehicles. A literature review focusing on car-trailer lateral stability control is presented, which covers the effects of external factors like aerodynamic forces, tire forces, and road and climatic conditions. To address the effects of these factors on the lateral stability of car-trailer combination, researchers have investigated numerous passive and active safety control techniques. Some promising control schemes, such as active trailer steering control (ATSC), active trailer braking (ATB) and model reference adaptive controller (MRAC) are analyzed. A comparative study of these control strategies is presented in terms of applicability and cost effectiveness.
2017-03-28
Technical Paper
2017-01-0347
Yat Sheng Kong, Dieter Schramm, M. Zaidi Omar, Sallehuddin Mohd. Haris, Shahrum Abdullah
This paper presents the development of a relationship between objective vehicle ride level and coil spring durability life using road data to shorten suspension design process. Current development processes of vehicle suspension systems which include vehicle ride and suspension spring durability are categorized into different stages of analysis and therefore, consumes lots of time. Through the developed predictive model, the ISO weighted accelerations were used to describe durability of spring components or vice versa. This model has led to immediate solution of suspension design with reduced number of testing. In order to construct the model, strain and acceleration data from various roads were measured using data acquisition which was involving car movements. Prior to the strain measurement, a finite element model of the spring was measured to identify the critical region of the spring and strain gauges were applied on the particular spot.
2017-03-28
Technical Paper
2017-01-1636
Lukas Preusser
Problem Already in the initial design failure mode analysis of this relatively young feature it became clear that an accurate sensor reading is critical to the performance of the heated steering wheel system. As the temperature reception capability of the human palm is very distinct, small deviations [≤0.1°??/??] from the targeted wheel temperature may be registered as "getting too hot" or "remaining too cold". As per industry standard, heated wheels only utilize a single sensor input to the temperature control circuitry, making it even more important for the sensor to reflect the current surface temperature. Certainly the sensor must be placed where it neither can be seen nor felt, decoupling surface from the sensor's temperature. Production tolerances for sensor placement on the heater mat along with heater mat placement tolerances relative to the armature's position add to the decoupling issue, causing unacceptably high or low steering wheel surface temperatures.
2017-03-28
Technical Paper
2017-01-1491
Manish Kumar Seth, Jens Glorer, Ralf Schellhaas
This paper outlines the invention, patented under patent number US 9,315,087 B2, on how a twist beam can be efficiently designed for a given roll stiffness by using the sectional properties of the beam section in combination with a long reinforcement and curved flanges. This helps in reducing the weight and cost in addition to improve the durability performance and camber compliance of the twist beam structure while using conventional stamping and welding technologies. As against the conventional method of changing the roll stiffness only with the thickness of the torsion beam, the invention detailed in this paper uses the shape and the thickness of the torsion profile to control the roll stiffness.The paper details the work done to develop the design concept and the validation using rig and vehicle level testing. This invention has been successfully patented with USPTO in 20166 (Patent number US 9,315,087 B2)
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