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Technical Paper
2014-04-01
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. Therefore, this paper analyzes the sensitivity of the motor parameters and proposes a method to improve the accuracy of identification results by changing the weight of identification results according to the operating conditions.
Technical Paper
2014-04-01
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.
Technical Paper
2014-04-01
Li Sun, Mohamed Awadallah, Lianhua Chi, Nong Zhang
Abstract This paper presents a smart electric scooter system consisting of a microprocessor based vehicle controller (integrating an embedded regenerative braking controller), a 300W Permanent Magnet (PM) DC motor, two low-power DC-DC converters to form a higher power DC-DC converter pack, a motor controller, a supercapacitor bank and a capacitor cell balancing sub-system. During acceleration or forward motoring mode, the vehicle controller sets the DC motor into motoring mode to further utilizing motor controller regulate wheel speed and acceleration torque, whereas during deceleration or forward braking mode, sets the DC motor into braking mode and further utilizing regenerative braking controller regulate wheel speed and braking torque, as well as functions as a constant current (whose reference value is adjustable via a potentiometer) generator to charge the supercapacitor bank in a controllable fashion, hence not only successfully replacing frictional braking to certain degree, but also increasing the total energy efficiency dramatically owing to the low internal resistance and larger capacitance of the supercapacitor compared with other conventional regenerative braking systems via batteries.
Technical Paper
2014-04-01
Takao Suenaga, Takahiro Jo
Abstract The automotive industry is placing high importance on technologies that can reduce CO2, even in a highly fuel-efficient compact car. One major technology is Stop & Start(S&S) System, with a combined energy regeneration system. A key component of the system is a power supply storage device that has high-charge acceptance, light weight, and compact size. We believe a Lithium-ion (Li-ion) battery completely meets these requirements. For the battery, there are three key points: 1 Battery cell specification2 State Of Charge (SOC) detection method3 Temperature management for Li-ion battery. We have already proposed the battery cell and the SOC detection during SAE 2013, and now we are going to introduce “Temperature Management”. If the temperature of a Li-ion battery operates over 60 degrees Celsius, the battery could be severely damaged. Therefore, temperature management of the battery is very important. Conventionally, the temperature is managed by several thermistors and a cooling fan.
Technical Paper
2014-04-01
Manchi Venkateswara Rao, Jos Frank, Mohit Kohli
Abstract Brake groan noise is resolved without any major change in the design of brake system and vehicle sub-system components in the development phase of a utility vehicle. The groan noise is observed during the end of the stopping of the vehicle under moderate braking. The concerned NVH issue is perceived as unacceptable noise in the passenger compartment. Groan induced vibration is subjectively felt on steering and seat frame. A typical process is established to successfully reproduce the groan which helped in precisely evaluating the effect of modifications proposed. The temperature range of the disc which has the highest probability to produce the groan noise is found out experimentally. The transfer path analysis is carried out to find the path contributions from suspension. Acoustic transfer functions from considered paths are measured with the suspension removed from vehicle. Effects of addition of mass on various locations of suspension and stiffness change of suspension bushings are studied.
Technical Paper
2014-04-01
Gary A. Davis
Abstract The critical speed method uses measurements of the radii of yawmarks left by vehicles, together with values for centripetal acceleration, to estimate the speeds of the vehicles when the yawmarks were made. Several field studies have indicated that equating the centripetal force with braking friction produced biased estimates, but that the biases tended to be small (e.g. within 10%-15% on average) and led to underestimates, suggesting that the method can be useful for forensic purposes. Other studies, however, have challenged this conclusion. The critical speed method has also seen use in safety-related research, where it is important to have a reliable assessment of the uncertainty associated with a speed estimate. This paper describes a variant of the critical speed method, where data from field tests lead to an informative prior probability distribution for the centripetal acceleration. Using Bayes theorem, this distribution is combined with the measured radius to produce a posterior probability distribution for the desired speed.
Technical Paper
2014-04-01
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. The active four steering (4WS) control system is designed to enhance vehicle lateral dynamics through controlling rear steer angle.
Technical Paper
2014-04-01
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.
Technical Paper
2014-04-01
Massimiliana Carello, Andrea Giancarlo Airale, Alessandro Ferraris
Abstract The use of composite materials is very important in automotive field to meet the European emission and consumption standards set for 2020. The most important challenge is to apply composite materials in structural applications not only in racing vehicles or supercars, but also in mass-production vehicles. In this paper is presented a real case study, that is the suspension wishbone arm (with convergence tie and pull-rod system) of the XAM 2.0 urban vehicle prototype, that it has the particular characteristics that the front and rear, and left and right suspension system has the same geometry. The starting point has been an existing solution made in aluminum to manufacture a composite one. The first step was the development of a dynamic model of the vehicle to understand the suspension loads and to define the suspension weight and stiffness target with respect to the solution made on aluminum, because it was necessary to understand the tensil strain on the component to simplify and optimize the geometry.
Technical Paper
2014-04-01
Andrew Nevin, Eric Daoud
Abstract Traditional tread depth measurements require manual utilization of a mechanical device to acquire measurements at each location of interest on a tire. Drive-over machine-vision sensors are becoming available as a means for measuring tread depth. These sensors typically consist of a laser and a camera contained in an environmentally-sealed sensor housing. Tires approach the sensor over the supporting surface, while a laser projects an illuminating line across the tread surface for capture in a digital image. This scan is evaluated to provide a single 2D contour of tread depth at the illuminated line. Advanced machine-vision sensors acquire a sequence of images, which results in a multitude of data points over a 3D region of the tread surface. Post-processing of the acquired images illustrates the observed tread pattern and establishes multiple tread depth measurements. Measurements determined by the advanced sensors from hundreds of tires were compared to manual measurements acquired with analog and digital mechanical gauges.
Technical Paper
2014-04-01
James Gramling
Abstract It is very important to note that most present-day CVT's drive with a friction element. Unlike gears that can be produced with any size necessary for the torque load they must transfer, CVT's are limited in torque capacity and are only marginally suitable for small vehicle applications. A system is described using two variable-inertia flywheels to not only supply the heavy torque requirements during acceleration of a vehicle but also operate in reverse capturing the otherwise wasted decelerating torque (I.E. braking torque). This system (called Kinetic Energy Power Transmission System or KEPTS) provides all of the documented benefits of the use of an IVT for motor vehicle acceleration and also incorporates regenerative braking. The significance of the system is that besides providing a complete KERS (kinetic energy recovery and storage) system, all accelerating and braking torque is provided by the two variable-inertia flywheels, thus allowing the main motive engine (ICE, electric traction motor, gas turbine, etc.) to operate at a fixed angular velocity (rpm) isolated from large torque variances, and the CVT elements can be minimized in size (I.E. low-torque).
Technical Paper
2014-04-01
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.
Technical Paper
2014-04-01
Tomislav Lovric, Manuel Schneider-Scheyer, Samir Sarkic
Abstract Today's Automotive ECU development is a global engineering exercise. It requires efficient planning, design and implementation. Time to market, innovative customer functions and cost effective design are key to success. Not only the technical realization with compressed time schedules and frequent change requests, but also the documentation, and the proof of compliance to ISO-26262 requires efficient solutions to be applied. Key to successful ECU development of complex safety critical systems inside a global team is a systematic approach to identify the ideal realization out of multiple design alternatives. This is why TRW Electronics Engineering for its Braking ECU products decided to design the new product generation with the help of Model Based System Engineering methods (MBSE). With these methods the team is realizing the opportunities provided by top-down driven development considering Requirements Engineering, Semi-formal Architecture Description, and early support to create evidence to conform to ASIL D in accordance to ISO 26262.
Technical Paper
2014-04-01
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. From the simulation results, it is shown that this active brake control strategy can not only ensure the flat tire vehicle stability, but also slow down the vehicle with a safe speed and for a shorter distance.
Technical Paper
2014-04-01
Jakub Zebala, Wojciech Wach
Abstract The objective of the paper is to present the results of an investigation of the effect of reduced tire pressure on car lateral dynamics in lane change maneuver. The intended aim was attained by performing bench and road tests. The aim of the bench tests was parameterization of the mathematical model of the tested car. The road tests covered the vehicle motion with reduced and no tire pressure on a curvilinear track adequate for bypassing an unexpected appearing obstacle. Next, simulations in PC-Crash were performed, and the results were compared with those obtained in experiments.
Technical Paper
2014-04-01
Renaud Deborne, Skárlet Khouri Silva, Andras Kemeny
Abstract By the action on the steering wheel, the driver has the capability to control the trajectory of its vehicle. Nevertheless, the steering wheel has also the role of information provider to the driver. In particular, the torque level at the steering wheel informs the driver about the interaction between the vehicle and the road. This information flow is natural due to the mechanical chain between the road and the steering wheel. Many studies have shown that steering wheel torque feedback is crucial to ensure the control of the vehicle. In the context of uncoupled steering (steer-by-wire vehicle or driving simulators), the torque rendering on the steering wheel is a major challenge. In addition, of the trajectory control, the quality of this torque is a key for the immersion of drivers in virtual environment such as in driving simulators. The torque-rendering loop is composed of different steps. At first, a vehicle dynamics model computes the torque level at the steering wheel regarding the vehicle state (steering wheel position, vehicle speed, etc.).
Technical Paper
2014-04-01
Klaus Greven, Manikandan Loganathan
Abstract The Counter Pressure Casting (CPC) process is particularly suited for the production of aluminum suspension components like wheel carriers or steering knuckles. Using a typical AlSi7Mg alloy such as A356 or EN AC-42100, yield strength above 260 MPa and elongation rates above 8% are possible in a high volume production. Although these are very good values for aluminum castings, the yield strength has to be improved to increase the light weight potential of such components. The present work shows how this goal can be achieved by the development of a new aluminum casting alloy. Besides the modification of Si and Mg content, the addition of Cr leads to an additional dispersion hardening effect. In this way, yield strength above 310 MPa combined with an elongation of 7% can be assured in the CPC process after a T6 heat treatment. Fundamental microstructural investigations are shown as well as the results of tensile tests, high temperature strength, corrosion behavior and static and dynamic component testing.
Technical Paper
2014-04-01
Daewon Jang, Sungbae Jang
Abstract Today, all manufacturers of vehicle are up for the challenge to abide in automobile emission control laws. Weight reduction is one of the best solutions to reduce both fuel consumption and emissions. The most effective method for the said idea is to have lightweight materials to some of parts of vehicle using the FRP(Fiber Reinforced Plastics). In order to obtain good mechanical properties of FRP, continuous fiber should be used. But it is difficult to design and manufacture of FRP parts using continuous fiber because of material properties and molding process. In this paper, it is used CF(carbon Fiber) and Epoxy to make a composite material Properties of this CFRP can be predicted through analysis. Tests and simulations of specimen are performed as every steps progress for correlation. And spring can be designed to meet all requirements for specific performance. The CFRP spring is made by new devices and methods and can be applied to vehicle for practical using. Patents regard to this devices were registered.
Technical Paper
2014-04-01
Daryl R. Poirier, Ravindra Patil, Robert Geisler, Joseph Schudt
Abstract The automotive industry is under great pressure to reduce vehicle mass for both cost and fuel economy gains. A significant contributor to body and suspension structure mass is peak vertical loads, primarily entering the body structure through the jounce bumper to body interface. This paper focuses on the successful development of “Loads Management Striker Caps” for the 2013 Cadillac ATS front and rear suspension. Component design and development of the striker caps was executed using explicit finite element analysis tools. Multi-body dynamics vehicle models were used to set component requirements and confirm striker cap performance for the vehicle during peak vertical events. The “Loads Management Striker Caps” ultimately reduced peak strut/shock tower loads by 40% in the front suspension and 25% in the rear suspension. This resulted in significant body and chassis mass savings, contributing to the Cadillac ATS's class leading curb weight.
Technical Paper
2014-04-01
Jonathan M. S. Mattson, Michael Mangus, Christopher Depcik
Abstract A timing sweep to correlate the location of Maximum Brake Torque (MBT) was completed on a single-cylinder, direct injected compression ignition engine that was recently upgraded to a high-pressure rail injection system for better engine control. This sweep included emissions monitoring for carbon dioxide, carbon monoxide, particulate matter, hydrocarbons, and oxides of nitrogen for the calibration of a heat release model, as well as the opportunity to relate MBT timing to brake-specific emissions production. The result of this timing sweep was a relatively linear correlation between injection delay and peak pressure timing. In addition, a number of other MBT timing methodologies were tested indicating their applicability for immediate feedback upon engine testing, particularly mass fraction burned correlations. Emissions were either strongly correlated to MBT timing (with emissions being minimized in the vicinity of MBT), or were completely independent of MBT. In addition, the end of the MBT timing envelope was linked to increased fuel consumption, as well as a rise in aromatic hydrocarbon emissions.
Technical Paper
2014-04-01
Austin Gurley
Abstract Selection of springs and dampers is one of the most important considerations when finalizing a race car suspension design. It is also one of most complex due to the dynamic interaction of the vehicle with the ground. Current tuning methods for spring and dampers' effect on vehicle ride can be based on simplified dynamic models of the vehicle, such as the quarter-car model. While efficient computationally, the traditional quarter-car model does not account for the non-linear variation in grip seen by a fluctuating contact-patch. Both amplitude and frequency of suspension oscillation contribute to loss of tire grip. The method can be improved by incorporation of a dynamic tire model, though resulting in non-linear effects. An improved ‘rolling quarter-car’ model is created, which includes the effect of dynamic tire forces in the analysis of improved grip. Using typical Formula SAE race car, characteristics as a test case, a linearized dynamic model is made. The effect of suspension parameters on the dynamic tire forces produced are surveyed.
Technical Paper
2014-04-01
Chen Lv, Junzhi Zhang, Yutong Li, Ye Yuan
Abstract Regenerative braking, which can effectively improve vehicle's fuel economy by recuperating the kinetic energy during deceleration processes, has been applied in various types of electrified vehicle as one of its key technologies. To achieve high regeneration efficiency and also guarantee vehicle's brake safety, the regenerative brake should be coordinated with the mechanical brake. Therefore, the regenerative braking control performance can be significantly affected by the structure of mechanical braking system and the brake blending control strategy. By-wire brake system, which mechanically decouples the brake pedal from the hydraulic brake circuits, can make the braking force modulation more flexible. Moreover, its inherent characteristic of ‘pedal-decouple’ makes it well suited for the implementation in the cooperative regenerative braking control of electrified vehicles. With the aims of regeneration efficiency and braking performance, a regenerative braking control algorithm for electrified vehicles equipped with a brake-by-wire system is researched in this paper.
Collection
2014-04-01
This technical paper collection focuses on new theory, formulation and modeling of amplitude-, frequency- and temperature-dependent nonlinear components/systems such as rubber and hydraulic mounts or bushings, shock absorbers, and any joint friction/damping; dynamic characterization through lab and field testing; Linearization methodology; Model validation, application, and sensitivity analysis in vehicle system/subsystem simulations; Nonlinear system identification, modeling, and application in testing accuracy improvement, etc.
Collection
2014-04-01
This technical paper collection is focused on vehicle dynamics and controls using modeling and simulation, and experimental analysis of passenger cars, heavy trucks, and wheeled military vehicles. The papers address active and passive safety systems to mitigate rollover, yaw instability and braking issues; driving simulators and hardware-in-the-loop systems; suspension kinematics and compliance, steering dynamics, advanced active suspension technologies; and tire force and moment mechanics.
Collection
2014-04-01
This technical paper collection presents papers on steering and suspension related topics as it applies to ground vehicles. Papers for this session address new approaches as well as advances in application of steering, suspension related technologies.
Technical Paper
2014-04-01
Lee Carr, Dan Barnes, Jennifer Crimeni
Abstract Prior to the widespread implementation of ABS brake technology in light vehicles, driver training often included instruction to “pump the brakes” to avoid locking the wheels. Many driver education programs now recommend maintaining high brake pedal force and relying on ABS. It is sometimes asserted that drivers desiring to stop a vehicle quickly still “pump the brakes”. Investigators sought to understand whether drivers desiring to decelerate quickly pump the brakes, especially in a way that may deplete the vacuum stored in a vehicle's brake booster if so equipped, or whether they apply the brakes in a manner corresponding to their desired deceleration. The National Highway Traffic Safety Administration (NHTSA) conducted a testing program to examine driver braking behavior in crash avoidance maneuvers. The data for those 245 test runs were reanalyzed, assessing patterns of brake pedal force application to determine whether pedal force variation was sufficient in magnitude and duration to reflect driver intent.
Technical Paper
2014-04-01
Ben Wen, Gregory Rogerson, Alan Hartke
Abstract Tire rolling resistance is one of tire performance indicator that represents a force needed to maintain the constant rolling of a tire. There are quite few methods and standards to measure tire rolling resistance, such as ISO-28585, ISO-18164, SAE-J1269, SAE-J2452, …. These tests have been used by tire companies, vehicle manufactures, and government agencies to evaluate tire rolling resistance performance. SAE-J1269 and SAE-J2452 are two popularly used multi-condition rolling resistance tests for passenger and light truck tires. Examining the test conditions and procedures of these two test standards showed that some key procedures and conditions from both standards are similar although there are many difference as well. The study presented here is to analyze test results from both tests and their correlation under certain conditions. If the correlation exists, one test may provide test results for both test conditions, therefore, test efficiency can be improved.
Technical Paper
2014-04-01
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.
Technical Paper
2014-04-01
Youichi Kamiyama
Abstract Tire cavity noise has long been one of the main road noise issues. Various ideas for devices to reduce tire cavity noise have been patented or discussed in technical reports, but many issues remain for commercialization, and at present only some tires have appeared as products. Therefore, technology was developed for mounting Helmholtz resonators on the wheels, enabling reduction of tire cavity noise without placing restrictions on the tires. The advantage of this technology is that the cost and productivity targets needed for mass production can be satisfied without impairing the tire and wheel functions. The aim of this development was to construct low-cost device technology that is well-suited to mass production and enables reduction of tire cavity noise to an inaudible sound pressure without adversely affecting dynamic product marketability such as strength and durability performance and handling performance. In order to realize that aim, the device configuration employed a structure that assembles separate thin, lightweight plastic resonators in the wheel well.
Technical Paper
2014-04-01
Felix Wittmeier, Timo Kuthada, Nils Widdecke, Jochen Wiedemann
Abstract The geometric shape of the tires can have a large influence on the aerodynamic drag of a passenger car as it has been shown already in different publications like for example [1, 2, 3]. However, to optimize the shape of a tire, nowadays quite some effort is needed in terms of wind tunnel time and costs for prototype tires. In this paper an approach to optimize the tire's shape in model scale is described, which can help to reduce both development time and costs. The first step in the development of this method was to verify that the aerodynamic effects of the tire geometry in model scale are comparable to full scale tests. This was achieved by measuring different production tires in full scale and also by measuring the quarter scale version of the same tires. The only difference between the original and the model scale tires was that the scaled tires were not deformable. The results show that the difference between two sets of tires is comparable in full scale and in quarter scale.
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