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Technical Paper

Downhill Safety Assistant Driving System for Battery Electric Vehicles on Mountain Roads

2019-09-15
2019-01-2129
When driving in mountainous areas, vehicles often encounter downhill conditions. To ensure safe driving, it is necessary to control the speed of vehicles. For internal combustion engine vehicles, auxiliary brake such as engine brake can be used to alleviate the thermal load caused by the continuous braking of the friction brake. For battery electric vehicles (BEVs), regenerative braking can be used as auxiliary braking to improve brake safety. And through regenerative braking, energy can be partly converted into electrical energy and stored in accumulators (such as power batteries and supercapacitors), thus extending the mileage. However, the driver's line of sight in the mountains is limited, resulting in a certain degree of blindness in driving, so it is impossible to fully guarantee the safety and energy saving of downhill driving.
Technical Paper

Control Synthesis for Distributed Vehicle Platoon Under Different Topological Communication Structures

2019-04-02
2019-01-0494
The wireless inter-vehicle communication provide a manner to achieve multi-vehicle cooperative driving, and the platoon of automotive vehicle can significantly improve traffic efficiency and ensure traffic safety. Previous researches mostly focus on the state of the proceeding vehicle, and transmit information from self to the succeeding vehicle. Nevertheless, this structure possesses high requirements for controller design and shows poor effect in system stability. In this paper, the state of vehicles is not only related to the information of neighbor vehicles, while V2V communication transmit information over a wide range of area. To begin with, the node dynamic model of vehicle is described by linear integrator with inertia delay and the space control strategy is proposed with different topological communication structures as BF, LBF, PBF, etc.
Technical Paper

Research on Multi-Vehicle Coordinated Lane Change of Connected and Automated Vehicles on the Highway

2019-04-02
2019-01-0678
With the rapid development of modern economy and society, traffic congestion has become an increasingly serious problem. Vehicle cooperative driving can alleviate traffic congestion and improve road traffic capacity. Compare with vehicle separate control, cooperative driving combines various vehicle systems, and highly integrates information on obstacle location, vehicle status and driving intention. Then the controller uniformly issues instructions to ensure the orderly driving of the platoon. In the cooperative driving platoon, the displacement difference and the speed difference between vehicles have a certain relationship, which reduces the possibility of traffic accidents and then improves the safety of driving. In the process of cooperative driving, if there are multiple vehicles whose speeds don’t meet the current lane requirements, or if there are obstacles ahead, multi-vehicle lane change measures must be taken.
Technical Paper

Lifetime Prediction Modeling of Automotive Proton Exchange Membrane Fuel Cells

2019-04-02
2019-01-0385
Knowledge about the health conditions and expected lifetime of an operating fuel cell stack is essential to system control and maintenance of a fuel cell vehicle. To quickly and accurately estimate a stack’s lifetime, a data-driven prediction model for proton exchange membrane fuel cells (PEMFCs) is proposed in this study. In this model, the voltage output of the fuel cell stack is taken as the lifetime evaluation index. Two methods are used to establish the lifetime decay evaluation criteria of the PEMFC stack, i.e., (1) Least Squares Fitting (LSF) method that establishes the standard for stack voltage degradation behavior, and (2) Back Propagation (BP) neural network that learns the stack’s voltage decay characteristics and establishes the standard for the stack’s voltage degradation behavior. The Autoregressive Moving Average (ARMA) time series model is then employed to learn part of the known decay behavior of stack voltage so as to predict future stack decay.
Technical Paper

An Optimization of Suspension Linkages for Wheel-Legged Vehicle

2019-04-02
2019-01-0167
The guiding mechanism of vehicle suspension can keep the wheels moving along planned trajectory. The geometrical design of the reasonable suspension guide mechanism can reduce the vibration transmitted to the body, improve trafficability and handling stability. The vehicle suspension design method was applied to the wheel-legged vehicle, enhancing ride performance. The optimization of suspension hard points can be obtained by using single variable method, adjusting each hard point coordinate independently. It is also widely recommended by using intelligent algorithm to solve well-designed multi-objective parameter optimization function. In this study, the multi-objective parameter optimization function was solved by using the NSGA-II (Non-dominated Sorted Genetic Algorithm-II). Computer simulations with half-car model were used to support the analysis in this study. ADAMS multibody dynamics software was also used to verify the reliability of the results.
Technical Paper

A Non-Contact Overload Identification Method Based on Vehicle Dynamics

2019-04-02
2019-01-0490
The vehicle overload seriously jeopardizes traffic safety and affects traffic efficiency. At present, the static weighing station and weigh-in-motion station are both relatively fixed, so the detection efficiency is not high and the traffic efficiency is affected; the on-board dynamic weighing equipment is difficult to be popularized because of the problem of being deliberately damaged or not accepted by the purchaser. This paper proposes an efficient, accurate, non-contact vehicle overload identification method which can keep the road unimpeded. The method can detect the vehicle overload by the relative distance (as the characteristic distance) between the dynamic vehicle's marking line and the road surface. First, the dynamics model of the vehicle suspension is set up. Then, the dynamic characteristic distance of the traffic vehicle is detected from the image acquired by the calibrated camera based on computer vision and image recognition technology.
Technical Paper

Energy Consumption Optimization for the Electric Vehicle Air Conditioning Using the Condensate Water

2019-04-02
2019-01-0148
In summer, the relatively low temperature water condenses in the evaporator when the vehicle air-conditioning (AC) is running. At present, the vehicle AC condensate water without well utilization is directly wasted. The condenser’s thermal transfer performance has a great influence on the AC performance, and to increase the convective heat transfer coefficient (CHTC) is the key to its design. In this paper, a method of using atomized condensate water (CW) to enhance the condenser’s thermal transfer performance is proposed, which can make the most of the CW's cold energy. It achieves the reuse of CW and increases the condenser’s CHTC. First, the CW flow calculation model in the evaporator and the calculation model of the condenser enhanced thermal transfer using atomized CW are both set up. The influence of the evaporation degree of atomized CW particles in the air on the enhancement effect is comprehensively considered.
Technical Paper

CATARC New Type Drivetrain NVH Test Facility

2019-04-02
2019-01-0788
A vehicle’s NVH performance has a significant impact on the user experience of the driver and passengers. About one-third of the vehicle complaints are related to NVH performance. As the core component of the vehicle, the drivetrain’s NVH characteristics have a significant impact on vehicle comfort. How to reliably and stably reproduce the specific condition of the whole vehicle through the test method, and obtain the highly consistent objective data for analyzing and improving the NVH characteristics of the drivetrain is of great significance in engineering. For this purpose, China Automotive Technology Research Center Co., Ltd. (CATARC) designed and built a new type drivetrain NVH test facility, which consists of five dynamometers, and can carry horizontal/vertical, front/rear drive or four-wheel drive structures including powertrain, transmission, and rear axle, or even a whole vehicle.
Technical Paper

Lightweight Design and Multi-Objective Optimization for a Lower Control Arm Considering Multi-Disciplinary Constraint Condition

2019-04-02
2019-01-0822
The requirement for low emissions and better vehicle performance has led to the demand for lightweight vehicle structures. Two new lightweight methods of design and optimization for the lower control arm were proposed in this research to improve the effectiveness of the traditional lightweight method. Prior to the two lightweight design and optimization methods, the static performance, including strength, stiffness and mode, and fatigue performance for the lower control arm were analyzed and they provided constraints for subsequent design and optimization. The first method of lightweight design and optimization was integrated application of topography optimization, size optimization, shape optimization and free shape optimization for the control arm. Topography optimization was first applied to find the optimal distribution form of reinforcement rib for the lower control arm. Size optimization was then applied in this study to optimize the plate thickness.
Technical Paper

Numerical Analysis of Underbody Diffusers with Different Angles and Channels

2019-04-02
2019-01-0668
The underbody diffusers are used widely in race cars to improve the flow field structure at the bottom of the car and provide enough downforce. In recent years, passenger cars have begun to use bottom diffuser to improve aerodynamic characteristics, so as to reduce drag and increase downforce. In this paper, the aerodynamic characteristics of the bus with different underbody diffuser angles and channel numbers are studied by numerical simulation analysis. Firstly, the aerodynamics of the bus under different diffuser inlet and outlet angles are studied, and then an optimal inlet and outlet angle is determined based on the simulation results. Then, using this angle as a constant, the 2, 3, and 4 channel numbers were chosen as the diffuser channel variables to study the influence of the multiple-channel diffusers on the aerodynamic drag of the vehicle.
Technical Paper

A Novel Vision-Based Framework for Real-Time Lane Detection and Tracking

2019-04-02
2019-01-0690
Lane detection is one of the most important part in ADAS because various modules (i.e., LKAS, LDWS, etc.) need robust and precise lane position for ego vehicle and traffic participants localization to plan an optimal routine or make proper driving decisions. While most of the lane detection approaches heavily depend on tedious pre-processing and great amount of assumptions to get reasonable result, the robustness and efficiency are deteriorated. To address this problem, a novel framework is proposed in this paper to realize robust and real-time lane detection. This framework consists of two branches, where canny edge detection and Progressive Probabilistic Hough Transform (PPHT) are introduced in the first branch for efficient detection.
Technical Paper

Robust Model Predictive Control for Path Tracking of Autonomous Vehicle

2019-04-02
2019-01-0693
Path tracking is one of the critical technologies in the autonomous vehicle. Its performance may be seriously affected by disturbance resulting from unpredictable environment like changes in road friction coefficient and parameter uncertainty such as cornering stiffness and mass caused by errors of measurement. Besides, since the vehicle system consisting of many systems is an extremely complex nonlinear system, it is almost impossible for us to establish a precise model of a vehicle especially when it is moving. These inevitable factors influence the control accuracy and even threaten the stability and safety of the vehicle system. This paper proposed a promising solution to this problem, robust MPC (Model Predictive Control) combined with the optimal preview controller for path tracking problems of an autonomous vehicle. The state space model in tracking error variables of a passenger vehicle used for path tracking application is established.
Technical Paper

Performance Analysis on 3D Printed Beak-Shaped Automotive Tail Fin Filled with Honeycomb Cellular Structure

2019-04-02
2019-01-0712
The concept of “bionic design” has driven the developments of automotive design. In this paper, a novel beak-shaped automotive tail fin with honeycomb cellular structure is proposed based on the idea of “bionic design”. Beak-shaped appearance is utilized to meet the requirement of aerodynamics performance, inner honeycomb cellular structure is filled to achieve more lightweight space. This paper starts from the establishment of three dimensional (3D) model based on the real characteristics of sparrow’s beak. On this basis, aerodynamic performances of novel beak-shaped tail fin and conventional shark tail fin are analyzed by experiment. Finally, the stiffness and modal analyses of solid beak-shaped tail fin and honeycomb beak-shaped tail fin are carried out respectively. The results indicate that the deformation of solid beak-shaped tail fin and honeycomb beak-shaped tail fin satisfy the basic requirements.
Technical Paper

Emergency Steering Evasion Torque Assistance Based on Optimized Trajectory

2019-04-02
2019-01-0888
When automobile is at the threat of collisions, steering usually needs a shorter longitudinal distance than braking to avoid collision, especially at a high speed. In emergency steering evasion, the vehicle may be out of the road or colliding with obstacles ahead when the driver’s steering torque is excessive or insufficient. In view of the above problems, this paper presents an emergency steering evasion torque assistance system based on optimized trajectory. First, a feasible steering evasion area is established which treats the paths of excessive and insufficient steering as boundary conditions in this paper. An optimized trajectory is derived from the lateral acceleration of the vehicle and the time to the adjacent lane as optimization conditions. Second, a two degree of freedom vehicle model is used to represent dynamics of the vehicle.
Technical Paper

Development and Research of Laser Ranging Vehicle Driving Deviation Test System

2019-04-02
2019-01-0926
Before the new car rolls from the line, due to assembly errors, inaccurate four-wheel positioning, etc., the vehicle will run off on a flat road, which will affect the driving comfort and safety. At present, most automobile manufacturers choose to perform the deviation test in the process of vehicle rolls from the line. Compared with other detection methods, the online deviation test system is developed with high precision of laser ranging, fast response and good reliability, which can realize fast and high-precision detection of vehicle deviation. In this paper, test system software is developed based on the LABVIEW, a variety of communication methods to build the communication system, using information check and queue task processing to control, to meet the test needs. Firstly, the calculation model of the deviation of the test system is established.
Technical Paper

Lightweight Design of CFRP Automobile Tailgate Based on Multi-Step Optimization

2019-04-02
2019-01-1103
As a critical part of auto-body, the design of tailgate not only affects the beauty, usability and safety of automobile, but also involves more and more issues about environmental protection and energy saving. Hence, it is of vital importance to investigate lightweight of tailgate. This paper mainly focuses on lightweight design of CFRP tailgate based on conventional SUV metal tailgate, which can be realized under the condition of meeting requirements of stiffness, modal and manufacturing with the adoption of multi-step optimization method. To start with, finite element (FE) model of metal tailgate is established. Meanwhile, the stiffness and modal analyses, including bending stiffness, torsional stiffness, lateral stiffness, vertical stiffness and free modal are set up. Then, the structural performances of metal tailgate are analyzed, and the topology optimization of CFRP tailgate is performed.
Technical Paper

Development and Verification of Control Algorithm for Permanent Magnet Synchronous Motor of the Electro-Mechanical Brake Booster

2019-04-02
2019-01-1105
To meet the new requirements of braking system for modern electrified and intelligent vehicles, various novel electro-mechanical brake boosters (Eboosters) are emerging. This paper is aimed at a new type of the Ebooster, which is mainly consisted of a permanent magnet synchronous motor (PMSM), a two-stage reduction transmission and a servo mechanism. Among them, the PMSM is a vital actuator to realize the functions of the Ebooster. To get fast response of the Ebooster system, a novel control strategy employing a maximum torque per ampere (MTPA) control with current compensation decoupling and current-adjusting adaptive flux-weakening control is proposed, which requires the PMSM can operate in a large speed range and maintain a certain anti-load interference capability. Firstly, the wide speed control strategy for the Ebooster’s PMSM is designed in MATLAB/Simulink.
Technical Paper

Accurate Pressure Control Strategy of Electronic Stability Program Based on the Building Characteristics of High-Speed Switching Valve

2019-04-02
2019-01-1107
The Electronic Stability Program (ESP), as a key actuator of traditional automobile braking system, plays an important role in the development of intelligent vehicles by accurately controlling the pressure of wheels. However, the ESP is a highly nonlinear controlled object due to the changing of the working temperature, humidity, and hydraulic load. In this paper, an accurate pressure control strategy of single wheel during active braking of ESP is proposed, which doesn’t rely on the specific parameters of the hydraulic system and ESP. First, the structure and working principle of ESP have been introduced. Then, we discuss the possibility of Pulse Width Modulation (PWM) control based on the mathematical model of the high-speed switching valve. Subsequently, the pressure building characteristics of the inlet and outlet valves are analyzed by the hardware in the Loop (HiL) experimental platform.
Technical Paper

Regenerative Braking Pedal Decoupling Control for Hydraulic Brake System Equipped with an Electro-Mechanical Brake Booster

2019-04-02
2019-01-1108
Electrification and intelligence are the important development directions of vehicle techniques. The Electro-Mechanical Brake Booster (Ebooster) as a brake booster which is powered by a motor, can be used to replace the traditional vacuum booster. Ebooster not only improves the intelligence level of vehicle braking and significantly improves the braking performance, but also adapts to the application in new energy vehicles and facilitates coordinated regenerative braking. However, Ebooster cannot complete pedal decoupling independently. It needs to cooperate with other components to realize pedal decoupling. In this paper, a pedal decoupling control algorithm for regenerative brake, which is based on the coordination control of Ebooster and ESP, is proposed. First, regenerative braking strategy is designed to distribute the hydraulic brake force and regenerative braking force.
Technical Paper

Passenger Cabin’s Parking Cooling System Based on TEC and Air Conditioning Condensate Water

2019-04-02
2019-01-1066
In the passenger cabin of the parking under the summer sun, the air’s average temperature will reach about 60°C. Such temperature can cause discomfort to the person who has just entered the passenger cabin, also can damage components of the passenger cabin. The reason for this phenomenon is because it is not convective with the outside air. Some vehicles use the electric power to drive the blower in order to ventilate, but the air’s temperature of cabin is so high that the blower’s effect of ventilation is limited. The system proposes to use solar energy to drive the automobile blower and the thermoelectric cooler(TEC) in order to cool the cabin’s air, and use the air-conditioning condensate water collected during the driving process to cool the TEC’s hot end to improve the cooling efficiency.
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