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SAE International Journal of Passenger Cars Electronic and Electrical Systems
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Influencing Factors Research on Vehicle Path Planning Based on Elastic Bands for Collision Avoidance

SAE International Journal of Passenger Cars - Electronic and Electrical Systems

Hunan University-Xiaolin Song, Haotian Cao, Jiang Huang
  • Journal Article
  • 2012-01-2015
Published 2012-09-24 by SAE International in United States
This paper presents the different influence factors to vehicle's path planning, including the guide-potential shape and its parameters, the guild-potential influence scale factor, the stiffness of the elastic bands and the speed of the host vehicle. The assessment of emergency path is based on the dynamic performance of the host vehicle, the lateral acceleration and yaw rate, and its mean-square values accesses the stability of the host vehicle when following the path. In order to take evasion maneuvers more steadily, a guide-potential affecting the moving vehicles behind the obstacle is built, which encourages the host vehicle to change lane appropriately. Three different shape guide-potential models, namely half-circle-like, half-ellipse-like and parabola-like, are proposed and compared in this paper. Meanwhile, hazard map of the road environment which includes the lanes, borders and obstacles is generated. Trajectory of low hazard level is generated based on virtual elastic bands which are composed with a number of nodes. Thus, the forces acting on the corresponding nodes of an elastic band are calculated by the directional derivate of those potentials. The…
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Fault-Tolerant Control of EMB Systems

SAE International Journal of Passenger Cars - Electronic and Electrical Systems

Kookmin Univ.-Young-Hun Ki, Hyun-Sik Ahn
MOBIS-Jae Seung Cheon
  • Journal Article
  • 2012-01-1795
Published 2012-09-17 by SAE International in United States
In this paper, for the fault-tolerant control of electro-mechanical brakes (EMBs), we continuously estimate several system variables and utilize these estimates to detect faulty sensor outputs. The clamping force is estimated by using the motor position and hysteresis phenomenon during clamping and releasing. Current sensor faults can be easily derived from the characteristics of a three-phase balanced circuit, and the motor position is estimated by applying different methods in low-speed and high-speed regions where a model-based approach is adopted. Using the proposed fault-tolerant logic, we can detect which sensor has a fault during driving or braking. Then, we use a bumpless transfer technique so that the control performance does not deteriorate when the estimated values are substituted for the measured values. The validity and the effectiveness of the proposed fault-tolerant control for an EMB are shown by using EMB hardware-in-the-loop simulations (HILS), so that fault tolerance is guaranteed for a scenario of sensor failures. The HILS consists of an EMB set, a TriCore-based actuator Electronic Control Unit (ECU), a host PC, and a CAN monitoring…
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High-Bandwidth Clamp Force Control for an Electromechanical Brake

SAE International Journal of Passenger Cars - Electronic and Electrical Systems

The University of Melbourne-Chih Feng Lee, Chris Manzie
  • Journal Article
  • 2012-01-1799
Published 2012-09-17 by SAE International in United States
A controller that fully utilizes the available motor capacity of an electromechanical brake to achieve high closed-loop bandwidth is proposed. The controller is developed based on the time-optimal switching curve derived from Pontryagin's Maximum Principle. The control input is scheduled using a switching surface based on the current motor velocity and position offset. Robustness to modeling errors is achieved by introducing a boundary layer in vicinity of the switching curve, reminiscent of a high gain controller. A flexible tuning procedure is also developed to aid in practical implementation, allowing a balanced choice between tracking speed and energy usage. The controller is implemented on a production-ready prototype EMB, and tested over different braking scenarios to assess the performance and robustness relative to the benchmark controllers. It is demonstrated that significant improvements in step response and dynamic tracking are obtained using the proposed approach.
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Adaptive Brake Torque Variation Compensation for an Electromechanical Brake

SAE International Journal of Passenger Cars - Electronic and Electrical Systems

The University of Melbourne-Chih Feng Lee, Chris Manzie
  • Journal Article
  • 2012-01-1840
Published 2012-09-17 by SAE International in United States
A novel method for attenuation of brake judder directly at the source is proposed, utilizing an electromechanical brake to actively compensate for the variation in brake torque that causes judder. Taking advantage of the high-bandwidth closed-loop clamp force tracking performance offered by an electromechanical brake, an adaptive compensator is designed to estimate the brake torque variation (BTV), and to produce a compensating clamp force command to cancel it. The compensator is tested over fixed and varying BTV frequencies by employing a production-ready prototype EMB. It is demonstrated that significant BTV attenuation is obtained using the proposed approach.
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Psychoacoustic Requirements for Warning Sounds of Quiet Cars

SAE International Journal of Passenger Cars - Electronic and Electrical Systems

BMW Group-Alfred Zeitler
  • Journal Article
  • 2012-01-1522
Published 2012-06-13 by SAE International in United States
According to upcoming legislative regulations in certain countries, electric and hybrid-electric vehicles (EVs and HEVs) will have to be equipped with devices to compensate for the lack of engine noise needed to warn pedestrians against the vehicles. This leads to the question of appropriate sound design which has to meet specific psychoacoustic requirements. The present paper focuses on auditory features of warning sounds to enhance pedestrians' safety with a major focus on the detectability of the exterior noise of the vehicle in an ambient noise. For the evaluation of detectability, the psychoacoustic model developed by Kerber and Fastl will be introduced allowing for the prediction of masked thresholds of the approaching vehicle. The instrumental assessment yields estimates of the distance of an approaching vehicle at the point it becomes audible to the pedestrians. This way the risk of collision can be assessed assuming that only auditory cues are used by pedestrians to identify vehicles before crossing a street. The corresponding algorithm was applied in a field study to assess the detectability of selected EVs and…
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Verification of ASSTREET Driver-Agent Model by Collaborating with the Driving Simulator

SAE International Journal of Passenger Cars - Electronic and Electrical Systems

Advanced Solutions Technology Japan, Ltd-Jun Tajima, Norihiko Sakamoto
Toyota Central R&D Labs., Inc.-Hiroshi Yasuda
  • Journal Article
  • 2012-01-1161
Published 2012-04-16 by SAE International in United States
This paper proposes a novel method of verifying comprehensive driver model used for the evaluation of driving safety systems, which is achieved by coupling the traffic simulation and the driving simulator (DS). The method consists of three-step procedure. In the first step, an actual driver operates a DS vehicle in the traffic flow controlled by the traffic simulation. Then in the next step, the actual driver is replaced by a driver model and the surrounding vehicle maneuvers are replayed using the recorded data from the first step. Then, the maneuver by the driver model is compared directly with the actual driver's maneuver along the simulation time steps. For example, while turning right (in front of the oncoming traffic), the proposed verification method was applied to our driver-agent model of traffic simulation system ASSTREET (The Advanced Safety System & Traffic REaltime Evaluation Tool) to demonstrate that the proposed method provides a straightforward way of verifying the driver-agent model capability to reproduce the driving behavior including the subtle driving behaviors, such as safety confirmation, that can have…
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Virtualized Fault Injection Methods in the Context of the ISO 26262 Standard

SAE International Journal of Passenger Cars - Electronic and Electrical Systems

Synopsys Inc.-Victor Reyes
  • Journal Article
  • 2012-01-0001
Published 2012-04-16 by SAE International in United States
Software quality is one of the biggest concerns of the automotive industry. Releasing a product with defects and having a recall can have enormous direct and indirect cost for an automotive OEM. In order to improve software quality is not sufficient to only increase the number of tests. It is extremely important to establish more sophisticated tests that can cover corner cases which are not unveiled during normal operation. Typically, corner cases are very difficult to test as those are often only triggered when the underlying hardware fails or the software gets unexpectedly corrupted. How to test those cases, to make sure that the right SW routines are executed and that the system moves back on time to a safe state? Fault-injection methods are typically used to cover a subset of these tests. However, there are quite some limitations on how effective and cost efficient existing methods can be applied for a more extensive coverage.The upcoming ISO 26262 Functional Safety standard defines fault-injection testing as a relevant method to be applied for different parts of…
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Schedule Design to Guarantee Freedom of Interference in Mixed Criticality Systems

SAE International Journal of Passenger Cars - Electronic and Electrical Systems

Symtavision GmbH-Christoph Ficek, Kai Richter, Nico Feiertag
  • Journal Article
  • 2012-01-0036
Published 2012-04-16 by SAE International in United States
The integration of mixed-criticality software according to safety standards like ISO 26262 generates new, parasitic mutual effects within the involved software architectures. In this situation, established schedule design patterns like RMS fail to deliver both efficiency and safety, in particular the freedom of interference. In today's practice of building a schedule, certain such measures to fulfill these safety requirements can conflict with efficiency requirements. The target of this paper is to present a sound approach of how to solve such requirement conflicts and to build up schedules that are safe and also efficient. We present a general early-stage procedure to build safe, certifiable, and efficient schedules. The procedure is based on the established design patterns and adds guidelines on how to exploit additional options in both schedule design and software partitioning. This procedure was validated against typical real-world systems and one example is presented.
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Development of a Path-following and a Speed Control Driver Model for an Electric Vehicle

SAE International Journal of Passenger Cars - Electronic and Electrical Systems

Univ of Waterloo-Kiumars Jalali, Steve Lambert, John McPhee
  • Journal Article
  • 2012-01-0250
Published 2012-04-16 by SAE International in United States
A two-passenger all-wheel-drive urban electric vehicle (AUTO21EV) with four in-wheel motors and an active steering system has been designed and developed at the University of Waterloo. In order to evaluate the handling and performance of such a vehicle in the design stage and analyze the effectiveness of different chassis control systems before implementing them in the real vehicle, the simulation of a large number of different open-loop and closed-loop test maneuvers is necessary. Thus, in the simulation environment, not only is a mathematical vehicle model needed for every test maneuver, but a driver model must also be designed to simulate the closed-loop test maneuvers. The role of the driver model is to calculate the control inputs required to successfully follow a predefined path. Such a driver model can be implemented as an inverse dynamics problem or by a representation of a driver that can look ahead, preview the path, and change the steering wheel angle and acceleration or brake pedal positions accordingly. In this regard, a path-following driver model is developed in this work with…
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Design of an Electric Variable CAM Phaser Controller

SAE International Journal of Passenger Cars - Electronic and Electrical Systems

Delphi Automotive-Gordon Cheever Jr, Charles Sullivan, Karl Schten, Ash Punater, Clinton Erickson
  • Journal Article
  • 2012-01-0433
Published 2012-04-16 by SAE International in United States
As the emissions and fuel economy standards for internal combustion engines become ever more stringent, a variety of valvetrain control methods have been developed to improve engine performance. One of these is camshaft (CAM) phasing, which controls the angular position of the CAM relative to the crankshaft allowing changes to the timing of valve lift events. This method has demonstrated advantages including broadening the engine torque curve, increasing peak power at higher RPM, reducing hydrocarbon and NOx emissions, and improving fuel economy. In addition, external EGR systems can be eliminated because internal cylinder dilution control can be achieved by varying CAM timing.Current implementations of CAM phasing use oil-pressure-based electro-mechanical systems. While these systems are relatively low cost and have proven to be robust, they have disadvantages at low oil temperatures and pressures (such as during cranking events). To overcome performance issues of oil based systems, Delphi has created a CAM phasing system using a brushless DC (BLDC) motor to drive the phasing mechanism. This approach provides full control independent of oil conditions and demonstrates increased…
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