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A Gear Shifting Indication Strategy of Eco-Driving Vehicle

Jiangsu University-Nannan Hu
Jiangsu University-Ren He
  • Technical Paper
  • 2020-01-0966
To be published on 2020-04-14 by SAE International in United States
The current indication strategies of gear shifting indication system for manual transmission vehicles are developed based on the gear shifting strategies of the automatic transmission vehicles. In this paper, it is found that the gear shifting frequency of automatic transmission vehicles is significantly higher than that of manual transmission vehicles based on the collected driving data of several automatic transmission and manual transmission vehicles, which increases the fatigue of drivers. Aiming at this problem, this paper proposes an interval algorithm of gear shifting indication strategy based on the fuel consumption rate of engine, which uses genetic algorithm to process the data of fuel consumption rate to find the maximum and minimum values ​​in the interval of torque and engine speed and adopts the interval algorithm to transform the search of least fuel consumption value into the seeking of optimal interval to avoid the shift busyness caused by the sudden change of fuel consumption rate. The gear shifting tolerance is defined to avoid the shift busyness while the evaluation function values for a pair of adjacent…
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Research on AEB Collision Avoidance Strategy Based on 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 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 peak adhesion 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 intervention comfort…
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Electronic Differential Control of Rear-Wheel Independent-Drive Electric Vehicle

SAE International Journal of Vehicle Dynamics, Stability, and NVH

Jiangsu University, China-Ren He, Hang Yun
  • Journal Article
  • 10-04-01-0004
Published 2019-12-02 by SAE International in United States
To track desired slip ratios and desired longitudinal speeds at the centers of driving wheels in the curve, this article proposes a hierarchical structured electronic differential control (EDC) of rear-wheel independent-drive electric vehicle (EV). In the high-level control, a fuzzy algorithm-based coefficient is computed according to the driver’s emotional intention of acceleration. The fuzzy algorithm-based coefficient is used to correct the desired driving torque of vehicle transmitting to the medium-level control. In the medium-level control, an optimization algorithm is developed to allocate the desired torques with requirement of as much accurate yaw moment as possible by the desired driving torque of the vehicle and yaw moment. And the desired longitudinal speeds at the centers of the rear left and right wheels are corrected twice, respectively, by Ackermann steering principle, considering the slip angle of the wheel and yaw moment. Based on the desired torques and desired longitudinal speeds at the centers of the rear left and right wheels from the medium-level control, desired slip ratios and desired angular speeds of the rear left and right…
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Modeling and Simulation of Refueling Emissions from Plug-in Hybrid Electric Vehicles

SAE International Journal of Fuels and Lubricants

Jiangsu University, China-Shu Liu, Ren He
  • Journal Article
  • 04-12-03-0014
Published 2019-10-14 by SAE International in United States
Vehicular evaporative emissions are an important source of volatile organic compounds (VOCs). Moreover, the engines of plug-in hybrid electric vehicles (PHEVs) may not start for a long time, causing the activated carbon canister to not purge well in-use and to become saturated with fuel vapor. Therefore, the problems of evaporative emissions and refueling emissions of PHEVs are still severe. The objectives of this article are to model and simulate the refueling emissions from PHEVs to shorten the design and development cycle. To achieve the goals, the release of refueling emissions is divided into two stages: the depressurization stage and the refueling stage. The mathematical model has been established by means of the ideal gas law and the gas mass transfer and diffusion law. Then, the numerical model is built and the volume of fluid (VOF) model was applied in the simulation. Moreover, the numerical model was validated by experiment on internal pressure increase of the fuel tank. The baseline case is conducted under the condition that the fuel dispensing rate is 50 L/min. Finally, different…
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Prediction and Control of Response Time of the Semitrailer Air Braking System

SAE International Journal of Commercial Vehicles

Jiangsu University, China-Ren He, Chang Xu
  • Journal Article
  • 02-12-02-0011
Published 2019-05-09 by SAE International in United States
The response time of the air braking system is the main parameter affecting the longitudinal braking distance of vehicles. In this article, in order to predict and control the response time of the braking system of semitrailers, an AMESim model of the semitrailer braking system involving the relay emergency valve (REV) and chambers was established on the basis of analyzing systematically the working characteristics of the braking system in different braking stages: feedback braking, relay braking, and emergency braking. A semitrailer braking test bench including the brake test circuit and data acquisition system was built to verify the model with typical maneuver. For further evaluating the semitrailer braking response time, an experiment under different control pressures was carried out. Experimental results revealed the necessity of controlling the response time. As a result, a braking pressure compensation system was designed through adding intake and exhaust solenoid valves to the original braking system. A proportional-integral-derivative (PID) control strategy optimized by genetic algorithm (GA) was adopted to generate pulse width modulation (PWM) signals applied to the solenoid valves…
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Stability Analysis of Combined Braking System of Tractor-Semitrailer Based on Phase-Plane Method

SAE International Journal of Commercial Vehicles

Jiangsu University-Ren He, Zhecheng Jing, Xiaomin Shen
  • Journal Article
  • 02-11-02-0012
Published 2018-06-04 by SAE International in United States
An analysis method for the stability of combined braking system of tractor-semitrailer based on phase-plane is investigated. Based on a 9 degree of freedom model, considering longitudinal load transfer, nonlinear model of tire and other factors, the braking stability of tractor-semitrailer is analyzed graphically on the phase plane. The stability of both tractor and semitrailer with different retarder gear is validated with the energy plane, β plane, yaw angle plane and hinged angle plane. The result indicates that in the long downhill with curve condition, both tractor and semitrailer show good stability when retarder is working at 1st and 2nd gear, and when it is at 3rd gear, the tractor is close to be unstable while semitrailer is unstable already. Besides, tractor and semitrailer both lose stability when retarder is working at the 4th gear.
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Simulation Analysis of Performance of the United Brake System of Bus

Jiangsu University-Ren He, Yong-tao Wang, Ying-sheng Zhao
Published 2007-08-05 by SAE International in United States
The math model of united brake system is set up on thinking of the influence of the coefficient of the revolving mass changes to linear mass of vehicle, the efficiency of slippage and so on. The simulation model is set up in the Simulink module of Matlab. The result of simulation shows that the braking distance is shortened by the function of united brake system in the emergency brake; the braking ability of the bus is improved. The united brake system can also be used to stop the bus in the nonemergercy brake. The retarder exhausts most of energy of automobile. Thus, the maintenance cost is reduced. The bus can run at steady and economic speed on the hillside path with continuous brake of united brake system.
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Sensibility Analysis About Structure Parameters to Braking Torque of Eddy Current Retard

Jiangsu Univ.-Ren He, Fengyan Yi, Chengye Liu
  • Technical Paper
  • 2005-03-0049
Published 2005-08-22 by Society of Automotive Engineers of Korea in South Korea
Sensibilities about structure parameters to braking torque of eddy current retarder are mainly studied in this paper. The relation between performance of eddy current retarder and structure parameters is deduced by using theory of electromagnetic field. Taking some kind of eddy current retarder as an example, the experiment of five structure parameters (diameter of iron core, distance between the center of the disk and the center of the pole, thickness of the disk, distance of air gap and material of disk) is designed by using orthogonal regression rotation design method. The influence laws of braking torque are researched under the circumstances of these five structure parameters in their mutual matching. Mathematical models of braking torque concerning five structure parameters are established with statistical software SPSS, the effects on braking torque is depicted quantified with regard to five structure parameters. Sensibilities about structure parameters to braking torques of eddy current retarder are found by partial derivatives to regression equation models. They are sequenced by material of disk (aluminum is superior to mild steel), thickness of the…

The Numerical Analysis of the Unsteady Thermal Field of the Rotor Plate for Eddy Current Retarder Using a New Style of Varying Time Step Method

Jiangsu Univ.-Chengye Liu, Ren He, Fengyan Yi
  • Technical Paper
  • 2005-03-0050
Published 2005-08-22 by Society of Automotive Engineers of Korea in South Korea
The physical model based on heat transfer theory and virtual boundary method for analyzing the unsteady thermal field of the rotor plate of eddy current retarder used in automobile is established and boundary conditions are defined in this paper. The FE (finite element) governing equation is derived using Galerkin method. The time differential item has been discrete based on Galerkin format that is stable at any condition. And a new style of varying time step method is used in iteration process. The thermal field on the rotor plate at the radial and axle directions is analyzed and the temperature distribution on two side-surfaces of the rotor plate at axel direction is measured. The testing and analytical data are uniform approximately. The wind tunnel structure and thickness of the rotor plate can be changed to achieve higher heat transfer coefficient and to lower temperature rise on the rotor plate, then braking performance stability of eddy current retarder can be improved.
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A Study of Braking Forces Distribution of Motor Vehicle By Grey System Theory

Jiangsu University of Science and Technology-Ren He
  • Technical Paper
  • 958496
Published 1995-11-04 by Society of Automotive Engineers of Japan in Japan
Based on the Grey system theory, a new analytic method for the braking force distribution of motor vehicle is presented. The braking force distribution between front and rear wheels of motor vehicle is studied by means of the incidence analysis of grey system theory. Since the incidence size represents the difference between actual braking force distribution curve β and ideal I curve of motor vehicle, so the optimal braking force distribution curve β can be hereupon found. The analysis of actual examples shows that the greater the incidence size, the closer are the actual braking force distribution curve and the ideal one.