Your Selections

Tongji University
Show Only

Collections

File Formats

Content Types

Dates

Sectors

Topics

Authors

Publishers

Affiliations

Events

   This content is not included in your SAE MOBILUS subscription, or you are not logged in.

Acoustic characteristics prediction and optimization of wheel resonators with arbitrary section

Tongji University-Rong Guo, Tiantian Mi
SAIC Motor Corporation Limited-Yimin Sun, Junlei Mao
  • Technical Paper
  • 2020-01-0917
To be published on 2020-04-14 by SAE International in United States
Tire cavity noise of pure electric vehicles is particularly prominent due to the absence of engine noise, which are usually eliminated by adding Helmholtz resonators with arbitrary transversal section to the wheel rims. This paper provides theoretical basis for accurately predicting and effectively improving acoustic performance of wheel resonators. A hybrid finite element method is developed to extract the transversal wavenumbers and eigenvectors, and the mode-matching scheme is employed to determine the transmission loss of the Helmholtz resonator. Based on the accuracy validation of this method, the matching design of the wheel resonators and the optimization method of tire cavity noise are studied. The identification method of the tire cavity resonance frequency is developed through the acoustic modal simulation and test. A scientific transmission loss target curve and fitness function are defined according to the noise characteristics. Combing the transmission loss prediction theory and particle swarm algorithm, the structure parameters of the wheel resonator are optimized. A remarkable attenuation of tire cavity resonance can be observed through test results.
   This content is not included in your SAE MOBILUS subscription, or you are not logged in.

Dynamic-static Optimization Design of Parking Robot Lifting Arm with Uncertain Parameters

Tongji University-Xiang Xu, Xinbo Chen, Zhe Liu, Yanan Xu, Yan Li, Yunkai Gao
  • Technical Paper
  • 2020-01-0511
To be published on 2020-04-14 by SAE International in United States
There are many uncertainties in engineering design, and the accumulated uncertainties will enlarge the overall failure probability of the structure system. Therefore, the structural design considering uncertainties is of high significance for improving its reliability. To address this issue, a dynamic-static structural topology optimization model is established and a reliability-based topology optimization (RBTO) with decoupling format is conducted in this study. At First, the design point which satisfies the constraint of target reliability indicator is obtained according to the reliability indictors of the first-order reliability method. Then, according to the sensitivity information of the random variable, the random variable is modified into a deterministic variable. Finally, the reliability-based deterministic topology optimization is performed by dividing the problem into two independent sub-problems of reliability analysis and equivalent deterministic topology optimization (DTO), and the feasibility of the structure optimization method is verified with the parking robot lifting arm. To meet the mechanical performances and lightweight requirements of the parking robot lifting arm, the mathematical model of dynamic-static multi-objective topology optimization for the lifting arm is established by…
   This content is not included in your SAE MOBILUS subscription, or you are not logged in.

Drivable area detection and vehicle location based on multi-sensor information fusion

Tongji University-Jie Bai, Sen Li, Jinzhu Wang, Libo Huang, Lianfei Dong
Suzhou Haomibo Technology Co. Ltd.-Panpan Tong
  • Technical Paper
  • 2020-01-1027
To be published on 2020-04-14 by SAE International in United States
Multi-sensor information fusion framework is the eyes for unmanned driving and Advanced Driver Assistance System (ADAS) to perceive the surrounding environment. In addition to the perception of the surrounding environment, real-time vehicle location is also the key and difficult point of unmanned driving technology. The disappearance of high-precision GPS differential signal and the defect of lane line will bring much more difficult for vehicle self-locating. In this paper, a road boundary feature extraction algorithm is proposed based on multi-sensor information fusion of automotive radar and vision to realize the auxiliary locating of vehicles. Firstly, we designed a 79GHz (78-81GHz) Ultra Wide Band(UWB)millimeter wave radar, which can obtain the point cloud information of road edge features such as guardrail or green belt and so on. Secondly, the pixel semantic information of the drivable area of road can be obtained by the pixel semantic segmentation of image information through deep learning. Then, the road boundary equation in vehicle coordinate system is obtained by clustering and fusion of the road boundary point cloud information and the boundary semantic…
   This content is not included in your SAE MOBILUS subscription, or you are not logged in.

A progress review on cold start methods and influence factors for automotive PEMFC system

Tongji University-Pengcheng Liu, Sichuan Xu
  • Technical Paper
  • 2020-01-0852
To be published on 2020-04-14 by SAE International in United States
This review presents comprehensive methods and influence factors of the research progress in solving the Proton Exchange Membrane Fuel Cells(PEMFC) system cold start problems with more than 100 patents, papers and reports. This may do some help for PEMFC system cold start from the point of practical utilization. This paper can be divided into six parts. Firstly, in introduction part, the recent achievements and goals will be summarized. Then, thanks to the cold start whole process includes PEMFC system shut down and cold start from subfreezing environment, so different actions or methods will be discussed based on system shutdown and cold start from subfreezing environment. Solutions and methods for fuel cell system shutdown are summarized into two categories: purge solution and keeping warm. In regard to the strategies for PEMFC system cold startup, different heating solutions are classified into self-heating strategies and auxiliary-heating heating depending on their heating sources. Solutions and strategies are compared and concluded based on the recent progress. Moreover, the whole process strategies will be concluded according to the relative researches. What’s…
   This content is not included in your SAE MOBILUS subscription, or you are not logged in.

Study on thermal management strategy of the exhaust gas of diesel engines based on in-cylinder injection parameters

Tongji University-Piqiang Tan, Lishuang Duan, Erfeng Li, Zhiyuan Hu, Diming Lou
  • Technical Paper
  • 2020-01-0621
To be published on 2020-04-14 by SAE International in United States
Due to high thermal efficiency, reliability and durability, less fuel consumption, and less carbon dioxide (CO2) emission, diesel engines are widely used in both stationary and mobile applications. However, an inherent combustion mode of diesel engines results in harmful emissions like hydrocarbons (HC), carbon monoxide (CO) and particulate matter (PM), the emissions can cause substantial damage to the human health and environment, so there are strict emission regulations to limit the harmful emissions. Diesel oxidation catalyst (DOC) and diesel particulate filter (DPF) are important exhaust gas aftertreatment devices to oxidizing the HC, CO and PM in order to meet the requirements of emission regulations. However, emission regulations become more stringent, the test procedure has been changed from New European Driving Cycle (NEDC) to Worldwide Harmonised Light Vehicle Test Procedure (WLTP), most of the test operating conditions in the WLTP are under medium and low engine loads, so the temperature of exhaust gas of diesel engines is relatively low during the whole WLTP cycle. For the exhaust gas aftertreatment system, especially for the regeneration process of…
   This content is not included in your SAE MOBILUS subscription, or you are not logged in.

Active and Passive Control of Torsional Vibration in Vehicle Hybrid Powertrain System

Tongji University-Lijun Zhang, Shijuan Zhang, Dejian Meng, Jie Xu
  • Technical Paper
  • 2020-01-0408
To be published on 2020-04-14 by SAE International in United States
The vibration characteristics of hybrid vehicles are very different from that of traditional fuel vehicles. In this paper, the active and passive control schemes are used to inhibit the vibration issues in vehicle hybrid powertrain system. Firstly the torsional vibration mechanical model including engine, motor and planetary gear subsystems is established. Then the transient vibration responses of typical working condition are analyzed through power control strategy. Consequently the active and passive control of torsional vibration in hybrid powertrain system are proposed. The active control of the motor and generator torque are designed and the vehicle longitudinal vibration is reduced. The vibration of the planetary gear system is ameliorated with passive control method by adding torsional vibration absorbers to power units. The vibration characteristics in vehicle hybrid powertrain system are effectively improved through the active and passive control.
   This content is not included in your SAE MOBILUS subscription, or you are not logged in.

Simulation Analysis of Early and Late Miller Cycle Strategies Influence on Diesel Engine Combustion and Emissions

Tongji University-Shuai Yang, Xiaolin Yang, Haifeng Liu, Zhiwei Feng
Jining Polytechnic-Xiuyuan Li
  • Technical Paper
  • 2020-01-0662
To be published on 2020-04-14 by SAE International in United States
Based on the working model of a diesel engine, the influence of 2 Miller cycle strategies-Early Intake Valve Closure (EIVC) and Late Intake Valve Closure (LIVC) on the combustion and emissions of diesel engine was analyzed, then the working condition of each Miller cycle strategies on the engine under the rated speed was optimized through the adjust of the valve timing, boost pressure and the injection timing. The research found that both delaying and advancing the closure timing of the intake valve can decrease the pressure and temperature during compression stroke, prolonging the ignition delay. However, due to the decrease of the working media inside the cylinder, the average in-cylinder temperature and soot emissions will increase, which can be alleviated by raising the boost pressure and the resulting compensation of the intake loss. The study found that together with increasing boost pressure and delaying injection timing, both EIVC and LIVC can reduce the NOx and soot emissions simultaneously. The simulation results show that while keeping the peak firing pressure the same as the original machine,…
   This content is not included in your SAE MOBILUS subscription, or you are not logged in.

Characteristics of Auto-ignition for Lubricants and Lubricant/Gasoline based on An Innovative Single Droplet Combustion System

Tongji University-Yang Yu, Kaifeng Pan, Jun Deng, Zongjie Hu, Wei Xie, Zhijun Wu, Liguang Li
  • Technical Paper
  • 2020-01-1428
To be published on 2020-04-14 by SAE International in United States
Due to the advantages of low weight, low emission and good fuel economy, downsized turbocharged gasoline direct injection (GDI) engines are widely-applied nowadays. However, Low-Speed Pre-Ignition (LSPI) phenomenon observed in these engines restricts their improvement of performance. Some researchers have shown that auto-ignition of lubricant in the combustion chamber has a great effect on the LSPI frequency. To study the auto-ignition characteristics of lubricant, an innovative single droplet auto-ignition measurement system for lubricant and its mixture is designed and developed, with better accuracy and effectiveness. The experiments are carried out by hanging lubricant droplets on the thermocouple node under active thermo-atmosphere provided by a small Dibble burner. The auto-ignition process of lubricant droplets is recorded by a high-speed camera. Influences of different base oil types, viscosities, calcium contents, initial droplet diameters, co-flow speeds, new oil, used oil and blending ratios of lubricant and gasoline on the ignition delay time of droplets are investigated at different droplet temperatures. The co-flow field temperature varies from 823K to 1323K. Equivalent diameters of droplets, 0.99mm, 1.24mm and 1.63mm, generated…
   This content is not included in your SAE MOBILUS subscription, or you are not logged in.

Nonlinear Model Predictive Control of Autonomous Vehicles Considering Dynamic Stability Constraints

Tongji University-Xunjie Chen, Guangqiang Wu, Meng Ren
  • Technical Paper
  • 2020-01-1400
To be published on 2020-04-14 by SAE International in United States
The autonomous vehicle performance is increasingly highlighted in many highway driving scenarios, which leads to more priorities to vehicle stability as well as tracking accuracy. In this paper, a nonlinear model predictive controller for autonomous vehicle trajectory tracking is designed and verified through a real-time driving simulator of a virtual test track. The dynamic stability constraints of nonlinear model predictive control (NLMPC) are obtained by a novel quadrilateral stability region criterion instead of the conventional phase plane method using the double-line region. First, a typical lane change scene of overtaking is selected and a new composited trajectory model is proposed as a reference path that combines smoothness of sine wave and comfort of linear functional path. Reference lateral velocity, azimuth angle, yaw rate, and front wheel steering angle are subsequently taken into account. Then, by establishing a nonlinear vehicle dynamics model where Magic Formula of nonlinear tire model is adapted, the quadrilateral vehicle stability region is defined in consideration of designed velocity, road adhesion coefficient, and front wheel steering angle. Working condition-variant constraints determined by…
   This content is not included in your SAE MOBILUS subscription, or you are not logged in.

Parameter Identification for A Proton Exchange Membrane Fuel Cell Model

Tongji University-Hao Yuan, Haifeng Dai, Xuezhe Wei
  • Technical Paper
  • 2020-01-0858
To be published on 2020-04-14 by SAE International in United States
The proton exchange membrane fuel cell (PEMFC) system has emerged as the state-of-art power source for the electric vehicle, but the widespread commercial application of fuel cell vehicle is restricted by its short service life. An enabling high accuracy model holds the key for better understanding, simulation, analysis, subsystem control of the fuel cell system to extract full power and prolong the lifespan. In this paper, a quasi-dynamic lumped parameters model for a 3kW stack is introduced, which includes filling-and-emptying cavity sub-models for the relationships between periphery signals and internal states, static water transferring sub-model for the membrane, and empirical electrochemical sub-model for the voltage response. Several dynamic experiments are carried out to identify unknown parameters of the model. According to the periphery measurable signals, the model is parameterized using a hybrid genetic algorithm (GA)/particle swarm optimization (PSO) method, which combined the advantages of conventional GA and PSO to reduce risks of being trapped into local optima. Comparison of the identified results and test voltages shows that the model is capable of predicting the voltage…