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Heavy Vehicles Kinematics of Automatic Emergency Braking Test Track Scenarios

NHTSA-Devin Elsasser
Transportation Research Center Inc.-M. Kamel Salaani, Christopher Boday
  • Technical Paper
  • 2020-01-0995
To be published on 2020-04-14 by SAE International in United States
This paper presents the test track scenario design and analysis used to estimate the performances of heavy vehicles equipped with forward collision warning and automatic emergency braking systems in rear-end crash scenarios. The first part of this design and analysis study was to develop parameters for brake inputs in test track scenarios simulating a driver that has insufficiently applied the brakes to avoid a rear-end collision. In the second part of this study, the deceleration limits imposed by heavy vehicles mechanics and brake systems are used to estimate automatic emergency braking performance benefits with respect to minimum stopping distance requirements set by Federal Motor Vehicle Safety Standards. The results of this study were used to complete the test track procedures and show that all heavy vehicles meeting regulatory stopping distance requirements have the braking capacity to demonstrate rear-end crash avoidance improvements in the developed tests.
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NHTSA's 2018 Heavy Vehicle Automatic Emergency Braking Test Track Research Results

NHTSA-Devin Elsasser
Transportation Research Center Inc.-M. Kamel Salaani, Christopher Boday
  • Technical Paper
  • 2020-01-1001
To be published on 2020-04-14 by SAE International in United States
This paper presents National Highway Traffic Safety Administration’s 2017 and 2018 test track research results with heavy vehicles equipped with forward collision warning and automatic emergency braking systems. Newly developed objective test procedures were used to perform and collect performance data with three single-unit trucks equipped with the crash avoidance systems. The results of this research show that the test procedures are applicable to many heavy vehicles and indicate that performance improvements in heavy vehicles equipped with these safety systems can be objectively measured.
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ROS and XCP in Traditional ECU Development

ETAS Inc.-Tobias Gutjahr, Matthew Roddy
  • Technical Paper
  • 2020-01-1367
To be published on 2020-04-14 by SAE International in United States
Originally developed for the service robot industry, the Robot Operating System (ROS) has lately received a lot of attention from the automotive sector with use cases, especially, in the area of advanced driver assistance systems and autonomous driving (ADAS/AD). Introduced as communication framework on top a of a host operating system, the value proposition of ROS is to simplify the software development in large-scale heterogeneous computing systems. Developers can focus on the application layer and let ROS handle the discovery of all participants in the system and establish communication in-between them. Despite the recent success of ROS, standardized automotive communication protocols such as the Universal Measurement and Calibration Protocol (XCP) are still dominant in the electronic control unit (ECU) development of traditional vehicle subsystems like engine, transmission, braking system, etc. XCP guarantees that common measurement and calibration tools can be used across different vehicles with ECUs from multiple suppliers. With the advancing area of ADAS/AD, we also expect the presence of ROS-based modules in the development of new vehicle platforms to increase. In this paper,…
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Super-Twisting Second-Order Sliding Mode Control for Automated Drifting of Distributed Electric Vehicles

Tsinghua University-Xiaohui Hou, Junzhi Zhang, Weilong Liu, Yuan Ji
  • Technical Paper
  • 2020-01-0209
To be published on 2020-04-14 by SAE International in United States
Studying drifting dynamics and control could extend the usable state-space beyond handling limits and maximize the potential safety benefits of autonomous vehicles. Distributed electric vehicles provide more possibilities for drifting control with better grip and larger maximum drift angle. Under the state of drifting, the distributed electric vehicle is a typical nonlinear over-actuated system with actuator redundancy, and the coupling of input vectors impedes the direct use of control algorithm of upper. This paper proposes a novel automated drifting controller for the distributed electric vehicle. First, the nonlinear over-actuated system, comprised of driving system, braking system and steering system, is formulated and transformed to a square system through proposed integrative recombination method of control channel, making general nonlinear control algorithms suitable for this system. On this basis, a super-twisting second-order sliding mode controller is designed to generate the desired virtual control input, pushing the vehicle to the performance and operating limits while keeping in the quasi-equilibrium state. Finally, an online control allocation is designed to translate the virtual control input to the longitudinal and lateral…
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Modeling and Identification of an Electric Vehicle Braking System: Thermal and Tribology Phenomena Assessment

Siemens Industry Software NV-Thomas D’hondt, Bart Forrier, Mathieu Sarrazin
Università degli Studi di Firenze-Tommaso Favilli, Luca Pugi, Lorenzo Berzi, Riccardo Viviani, Marco Pierini
  • Technical Paper
  • 2020-01-1094
To be published on 2020-04-14 by SAE International in United States
A rapidly shifting market and increasingly stringent environmental regulations require the automotive OEMs to produce more efficient and low-emission electric vehicles. Regenerative braking has proven to be a major contributor to both objectives, enabling the charging of the batteries during braking on one side, and a reduction of the load and wear of the brake pads on the other side. The optimal sizing of such systems requires the availability of good simulation models to improve their performance and reliability at all stages of the vehicle design. This enables the designer to study both the integration of the braking system with the full vehicle equipment and the interactions between electrical and mechanical braking strategies. The present paper presents a generic simulation framework for the thermal and wear behavior of a mechanical braking system, based on a lumped parameter approach. The thermal behavior of the system is coupled back to the friction coefficient between the pad and the disc to assess its effect on braking performance. Additionally, the effect of wear and temperature on the generation of…
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Simulation of the Combined Braking Control System for Hybrid Electric Vehicles

Kharkiv National Automobile and Highway University-Serhii Shuklynov, Mykhailo Kholodov, Leonid Ryzhykh
VN Karazin Kharkiv National University-Victor Verbitskiy
  • Technical Paper
  • 2020-01-0217
To be published on 2020-04-14 by SAE International in United States
Simulation model of the combined braking control system for hybrid electric vehicles is proposed. The model shows working processes of the braking system with actuating friction mechanisms and an electro-hydraulic drive and regenerative braking system with an electrodynamic mechanism. The electrodynamic actuating braking system is formed by transferring the traction motor to the generator operating mode. At the same time braking effect is transmitted through the transmission to the drive wheels. The combined control of two brake systems of an electric vehicle is carried out by the driver when acting on one common control element - the brake pedal. Acting on the braking pedal, driver generates the given control signal- desirable level of electric vehicle deceleration. In accordance with the given control signal, the law of control can be selected in the simulation model - the control function (electric vehicle deceleration) is proportional to the pedal effort or the control function is proportional to the set value of deceleration. In this case, the control system is adaptive and corrects the control signal in accordance with…
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Modelling of a combined system of hydraulic magnetorheological fluid damper with braking-by-wire system

Tsinghua University-Cenbo Xiong, Liangyao Yu, Zhenchuan Li, Zhenghong Lu, Abi Lanie
  • Technical Paper
  • 2020-01-0988
To be published on 2020-04-14 by SAE International in United States
A hydraulic chamber is embedded in serial with the accumulator of a normal mono-tube magnetorheological fluid damper (MRFD). The damper stiffness can be adjusted by changing the initial accumulator volume with the hydraulic chamber. This hydraulic chamber is connected to an electric pump and controlled by the braking-by-wire system. Some signals and control parameters of the braking system are shared with the suspension system. A modified bi-viscosity magnetorheological fluid (MRF) model that explicitly includes the parameter of control current is adopted to determine the viscous forces of the damper. A dynamic model of this hydraulic MRFD is subsequently set up based on the hydro dynamic system and the MRF model. In this scheme, both the MRF viscosity and the damper stiffness can be continuously adjusted at the same time. A theoretical model combining the vehicle dynamics, the braking-by-wire system and the hydraulic MRFD is established based on which the control principles of the hydraulic MRFD according to the braking intensity are revealed. Simulations are carried out to study the parametric influences of this combined braking…
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Fault-tolerant control of regenerative braking system on In-Wheel Motors Driven Electric Vehicles

Xiaohui Hou
Tsinghua University-Yuan Ji, Junzhi Zhang, Weilong Liu
  • Technical Paper
  • 2020-01-0994
To be published on 2020-04-14 by SAE International in United States
A novel fault tolerant brake strategy for In-wheel motor driven electric vehicles based on integral sliding mode control and optimal online allocation is proposed in this paper. The braking force distribution and redistribution, which is achieved in online control allocation segment, aim at maximizing energy efficiency of the vehicle and isolating faulty actuators simultaneously. The In-wheel motor can generate both driving torque and braking torque according to different vehicle dynamic demands. In braking procedure, In-wheel motors generate electric braking torque to achieve energy regeneration. The strategy is designed to make sure that the stability of vehicle can be guaranteed which means vehicle can follow desired trajectory even if one of the driven motor has functional failure. Considering longitudinal velocity and yaw velocity control, Electric vehicle with four independent In-wheel driven motor is a typical over-actuated control system whose control inputs outnumbers the state variables. Therefore, typical nonlinear controller design methods based on Lyapunov theory can not be applied directly. In this paper, the problem is settled down by transferring the input matrix whose dimension is…
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A collision avoidance strategy of autonomous emergency braking based on the characteristics of driver-vehicle-road

Jiangsu University-Ren He, Dong Zhang
  • Technical Paper
  • 2020-01-1213
To be published on 2020-04-14 by SAE International in United States
With the rise of intelligent transportation systems around the world, research on automobile active safety technology has gained widespread attention. Autonomous Emergency Braking(AEB) which can avoid or mitigate collision by active braking has become a hot research topic in the field of automobile. However, there are some limitations in the present Autonomous Emergency Braking(AEB) collision avoidance strategy, including lack of effective identification of road adhesion conditions, mismatch of active braking system parameters and imperfection of target vehicle motion information, which leads to poor collision avoidance performance on low adhesion coefficient road surface and intervention with the normal driving operation of the driver. A new collision avoidance strategy for AEB is proposed in this paper. Firstly, a new safe distance collision avoidance model is established based on the tire-road maximum friction coefficient in real time, the performance parameters of the active braking system and the motion information of the target vehicle. Secondly, under the premise of not interfering with the driver's normal collision avoidance operation, an AEB collision avoidance strategy that can balance vehicle safety and…
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Non-contact Overload Vehicle Recognition by Vehicle to Roadside Unit

Cong linpeng
  • Technical Paper
  • 2020-01-0940
To be published on 2020-04-14 by SAE International in United States
Overloading of vehicles will affect the safety of driving, aggravate the wear of automobile brake system and make the braking distance of overloaded vehicles too long. Secondly, when the vehicle is overloaded, due to the increase of load, the stress will exceed the allowable value, which will cause early wear and damage of the parts, resulting in a decrease in the reliability of the service life of the vehicle. At present, for the detection of overloaded vehicles, most areas still adopt the method of static overload detection station or adopt the monitoring mode of traditional manual watching by installing video monitoring system. It is not efficient at all. To solve these problems, a overload vehicle detection system based on V2R (Vehicle to Roadside Unit) is developed. The system collects engine speed, engine torque and other signals through the CAN (Controller Area Network), and uses DSRC (Dedicated Short Range Communications) to directly transmit the vehicle data information to the roadside detection unit. As the speed signal collected by CAN is detected by wheel speed sensor, and…