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Technical Paper

Self-exploration of Non-holonomic Automated System Under Dynamic Environment

2020-04-14
2020-01-0126
Exploring an unknown place autonomously is a challenge for robots, especially when the environment is changing. Moreover, in real world application, efficient path planning is crucial for the autonomous vehicles to have timely response to execute a collision-free motion. In this paper we focus on environment exploration which enables an automated system to establish a map of an unknown environment with dynamic objects moving within it. We introduce an exploration package that enables robot’s self-exploration with an online collision avoidance planner. The package consists of exploration module, global planner module and local planner module. We modularize the package so that developers can easily make modifications or even substitutions to some modules for their specific application. In order to validate the algorithm, we designed and built a robot car as a low cost validation platform to test the autonomous vehicle algorithms in the real world.
Technical Paper

Urban Pilot Motion Planning and Control Deployment via Real-Time Multi-Core Multi-Thread Prototyping

2020-04-14
2020-01-0125
In this work, the functional development of motion planning and control for SAE level-4 autonomous urban pilot is presented, including its architecture design, algorithm development, software implementation and hardware prototype. First, a completely AVL in-house designed, modular and generic Advanced Driver Assist System (ADAS) and Automated Driving (AD) application architecture is deployed, such that the motion planning and control modules can communicate with decision making, environment modeling and localization modules. Second, A road-navigation-oriented, sampling-and-searching-based iterative spatial-temporal motion planning algorithm is developed and integrated with classical motion control algorithms, via a MATLAB/Simulink implementation platform. Finally, the integrated motion planning and control subsystem is prototyped in Speedgoat hardware, via a real-time multi-core multi-thread deployment methodology.
Technical Paper

Platooning Vehicles Control for Balancing Coupling Maintenance and Trajectory Tracking

2020-04-14
2020-01-0128
Recently, car-sharing services using ultra-compact mobilities have been attracting attention as a means of transportation for one or two passengers in urban areas. A platooning system consisting of a manned leader vehicle and unmanned follower vehicles can reduce vehicle distributors. We have proposed a platooning system which controls vehicle motion based on the relative position and posture measured by non-contact coupling devices installed between vehicles. The feasibility of the coupling devices was validated through a HILS experiment. There are two basic requirements for realizing our platooning system; (1) all devices must remain coupled and (2) follower vehicles must be able to track the leader vehicle trajectory. Thus, this paper proposes two vehicle control method for satisfying those requirements. They are the “device coupling and trajectory tracking merging method” and the “trajectory shifting method”.
Technical Paper

Automated highway driving motion decision based on optimal control theory

2020-04-14
2020-01-0130
According to driving scenarios, intelligent vehicle is mainly applied on urban driving, highway driving and close zone driving, etc. As one of the most valuable developments, automated highway driving has great progress. This paper focuses on automated highway driving decision, and considering decision efficiency and feasibility, a hierarchical motion planning algorithm based on dynamic programming was proposed, and simultaneously, road coordinate transformation methods were developed to deal with complex road conditions. At first, all transportation user states are transformed into straight road coordinate to simplify modeling and planning, then a set of candidate paths with Bezier form was developed and with the help of obstacles motion prediction, the feasible target paths with collision-free were remains, and via comparing vehicle performance for feasible path, the optimal driving trajectory was generated.
Technical Paper

Personalized Human-Machine Cooperative Lane-change Based on Recurrent Neural Network

2020-04-14
2020-01-0131
To reduce the interference and conflict of human-machine cooperative control and improve the friendliness and acceptability of intelligent vehicles, a personalized human-machine cooperative lane-change method was proposed. Firstly, a test platform with active steering in the loop was built based on MATLAB/Simulink and PreScan. The lane-change test condition for data collection were designed, and the lane-change behaviors data of five drivers with different personalities were collected. Then, a multi-layer recurrent neural network (RNN) was built based on Long Short-Term Memory (LSTM) to learn the lane-change behaviors of each driver and a personalized lane-change method was trained for each driver. In addition, the lane-change data from previous research that did not include these five drivers was used to retrain the RNN, and this RNN was used as the default lane-change method for comparison.
Technical Paper

Iterative Dynamic Programming Based Model Predictive Control of Energy Efficient Cruising for Electric Vehicle with Terrain Preview

2020-04-14
2020-01-0132
Energy-oriented cruising control strategies for conventional vehicles have been studied for several years and tend to use model predictive control (MPC) to optimize the vehicle velocity with terrain profile preview. For electric vehicle (EV) with regenerative braking, the velocity profile should be different from conventional vehicles. As a global optimization method, dynamic programming (DP) can be implemented to calculate the optimal velocity for EV on given driving cycles. Due to its terrible computational burden, conventional DP is not suitable for real-time implementation especially with higher dimensions. In this paper, we propose an iterative dynamic programming (IDP) approach to reduce computing time firstly. The IDP can obtain the optimal control laws alike the conventional DP by converging the optimal control strategy iteratively within an adaptive multidimensional search space.
Technical Paper

A Novel Velocity Planner for Autonomous Vehicle Considering Human Driver’s Habits

2020-04-14
2020-01-0133
In automatic driving application, the velocity planner can be considered as a key and critical factor to ensure the comfort performance. One of the most important tasks of the velocity planner is to simulate the velocity characteristics of human drivers. In this paper, two Driver In-the-Loop (DIL) experiments are designed to explain velocity characteristics of human drivers. In the first experiment, static obstacles are placed on both sides of the straight road to shorten the cross range that vehicles can driver across. Moreover, different cross ranges are set to study the influence of the steering wheel error on the velocity. In the second experiment, velocity characteristics of human drivers are investigated under the condition of different road widths and curvatures in a U-shaped turning road contour. In both DIL tests, different driving styles are analyzed through the operation result of several drivers, including throttle, braking, and steering.
Technical Paper

Decision making and trajectory planning of a novel vehicle lane-changing control method inspired by automatic parallel parking

2020-04-14
2020-01-0134
With the development of automation technology in automobiles, lane-changing systems have been developed and applied to improve environmental adaptability of advanced driver assistant system (ADAS) as well as driver comfort. Lane-changing control consists of three steps: decision making, trajectory planning and trajectory tracking. Decision making and trajectory planning are usually integrated in recent studies, where decision making is related to potential trajectories so that environmental adaptability is improved. However, current methods are not perfect due to weaknesses like high computation cost, low robustness to uncertainties, etc. In this paper, a novel lane changing control method is proposed, where lane-changing behavior is analogized to parallel parking behavior. The focus of this study lies on decision making and trajectory planning.
Technical Paper

A Secure and Privacy-Preserving Collaborative Machine Learning System for Intelligent Transportation System

2020-04-14
2020-01-0139
Autonomous vehicles assemble multiple intelligent mobility solutions to create an intelligent transportation system on the road. The intelligent mobility solutions across autonomous vehicles are achieved using advanced machine learning algorithms. The intelligence of the machine learning algorithms is proportional to the amount of variations in the training data fed into the algorithms. The static machine learning algorithms in the autonomous driving system fails to handle the new variations in the dynamic input data, which requires the continuous retraining of the machine learning models to adapt to the changes in input distribution. The dynamic driving environment through which the machine learning algorithms retrains differs from vehicle to vehicle.
Technical Paper

Connected-Vehicles Shared Images Registration System Using Harris-Stephens Approach

2020-04-14
2020-01-0141
Connected vehicles technology allows to share information between road elements, like vehicles, pedestrians and infrastructure. The main goal of the connected vehicles technology is to improve road safety and achieve autonomous driving. Many kinds of information can be shared over connected vehicles, like navigation information, road conditions and weather conditions. Videos and images are also important information to be shared over the connected vehicles network due to the rich information they carry to achieve autonomous driving, especially when they are processed by machine learning algorithms to detect and classify road objects. One of the issues in dealing with the images shared over connected vehicles is the image registration. Because the cameras used in vehicles have different specifications, like resolution, field of view and alignment. To analyze these images by computer vision algorithms, images have to be registered and aligned together.
Technical Paper

Enriching systems theory based cyber-security and safety analysis using stakeholder value networks

2020-04-14
2020-01-0143
System-theoretic process analysis for security (STPA-Sec) is a powerful safety and security analysis method that focuses on unsafe and unsecure interactions between subsystems rather than component failure and its resulting chain-of-event failure modes. The first step of STPA-Sec requires the analyst to identify the system boundary and list the system losses and hazards. Current approach to performing this first and critical step of STPA-Sec requires interviewing the stakeholders and could potentially result in a narrow focus due to stakeholder’s mental model and resulting answers to questions. In some cases, stakeholders are not available for interviews and we risk influencing the system loss identification by the mental model of the analyst. We believe these two potential issues in the STPA-Sec analysis: narrow focus, and missing access to stakeholder can be address by factoring additional system information through stakeholder analysis.
Technical Paper

An Integrated View on Automotive SPICE, Functional Safety and Cyber-Security

2020-04-14
2020-01-0145
Automotive domain has seen safety engineering at the forefront of the industry’s priorities for the last decade. Therefore, additional safety engineering efforts, design approaches and well-established safety processes have been stipulated. Today many connected and automated vehicles are available and connectivity features and information sharing is increasingly used. This increases the attractiveness of an attack on vehicles and thus introduces new risks for vehicle cyber-security. Thus, just as safety became a critical part of the development in the late 20th century, the automotive domain must now consider cyber-security as an integral part of the development of modern vehicles. Aware of this fact, the automotive industry has therefore recently taken multiple efforts in designing and producing safe and secure connected and automated vehicles.
Technical Paper

A Lumped-Parameter Thermal Model for System Level Simulation of Hybrid Vehicles

2020-04-14
2020-01-0150
Commercial vehicle electrification is a path to meeting stringent fuel consumption and emission targets. Considering extended operations in different applications, the powertrain components need to be selected and sized together with the cooling system to ensure consistent performance and longer product life. In order to maintain the interactions between subsystems in the optimization routines, multi-physics models should be utilized. A simplified thermal network model is developed in this work for hybrid powertrain cooling systems based on the analogy between heat transfer and current flow equations. The assumption of a lumped system is valid for these components as the conductive heat transfer is much higher than convective heat transfer (Biot number <0.1). The energy equations are solved to calculate component temperatures in state space form, whereas, in literatures, detailed object-oriented 1-D models are mainly used for this purpose.
Technical Paper

Adaptive sampling in the design space exploration of the automotive front end cooling flow

2020-04-14
2020-01-0149
Adaptive sampling in the design space exploration of the automotive front end cooling flow (Author)Venkata Krishna Mohan Chagarlamudi, FCA NA - mohan.chagarlamudi@fcagroup.com, (Co-Author) Arturo Guzman FCA NA - arturo.guzman@fcagroup.com, (Co-Author) Mark Doroudian FCA NA - mark.doroudian@fcagroup.com, (Co-Author) Dr. Malik KAYUPOV Dassault Systemes Simulia Corp - malik.kayupov@3ds.com One of the key inputs 1-D transient simulation takes is a detailed front end cooling flow map. These maps that are generated using a full vehicle 3D CFD model require expensive computational resources and time. This paper describes how an adaptive sampling of the design space allowed the reduction of computational efforts while keeping desired accuracy of the analysis. The idea of the method was to find a pattern of DOE sampling points for 3D CFD simulations that would allow a creation of an approximation model accurate enough to predict output parameter values in the entire design space of interest.
Technical Paper

Development of CFD Program for Automotive Ventilation and Defrost Simulation using OpenFOAM

2020-04-14
2020-01-0154
Numerical simulations are used to predict performance in the automotive development process. In particular, ventilation and defrost performances of automotive HVAC system are developing according to design variables and environmental conditions based on computational fluid dynamics (CFD). Recently, computer hardware performance and analysis technology are improved and the proportion of simulation is increasing accordingly. However, cost of software license also increases in these development environments. In this paper, we developed CFD program(GUI) with OpenFOAM to analysis automotive ventilation and defrost. This program includes improved turbulent model and the fluid film model for ventilation and defrost analysis that don’t support in the open library.
Technical Paper

Modeling of an Integrated Internal Heat Exchanger and Accumulator in R744 Heat Pump Operation

2020-04-14
2020-01-0153
Carbon dioxide (R744) is one of the most promising next-generation refrigerants for mobile air-conditioning applications (MAC), which has the advantages of good heating performance in cold climates and environmental-friendly properties. In this paper, a simulation model of an integrated internal heat exchanger (IHX) and accumulator (ACC) was developed using the finite volume method via EES. The results were validated by experimental results from a transcritical R744 mobile heat pump, and the error was within ±5%. The impacts of mass flow rate, evaporator outlet quality and temperatures of high- and low-side streams on the heat transfer rate, effectiveness and charge of the integrated IHX/Acc were studied. Results show that the heat transfer rate of the IHX is mostly sensitive to the evaporator outlet quality. When the evaporator quality decreases from 0.9 to 0.6, the heat transfer rate increases from 1.1 to 2.4 kW and the superheat reduces from 25.8 to 9.4 ℃.
Technical Paper

Development of cooling fan model and heat exchange model of condenser to predict the cooling performance and the heat resistance performance of vehicle

2020-04-14
2020-01-0157
The cooling performance and the heat resistance performance of commercial vehicle are balanced with aerodynamic performance, output power of power train, styling, the location of sensors, cost and many other parameters. Therefore, it is desired to predict the cooling performance and the heat resistance performance with high accuracy at the early stage of development. Three forms of heat transfer consist of conduction, convection and radiation. Among of these components, it is sometimes difficult to solve the thermal conduction accurately, because to prepare accurate shape and properties needs lots of time and efforts at the early stage of development. Therefore, the cooling performance of heat exchangers and the air temperature distribution in the engine compartment are predicted to access the cooling and the heat resistance performance of vehicle at the preliminary design stage.
Technical Paper

Numerical investigation of heat retention and warm-up with thermal encapsulation of powertrain

2020-04-14
2020-01-0158
Powertrain thermal encapsulation has the potential to improve fuel consumption and CO2 via heat retention. Heat retained within the powertrain after a period of engine-off, can increase the temperature of the next engine start hours after key-off. This in turn reduces inefficiencies associated with sub-optimal temperatures such as friction. The Ambient Temperature Correction Test was adopted in the current work which contains two World-wide harmonised Light duty Test Procedure (WLTP) cycles separated by a 9-hour soak period. A coupled 1D – 3D computational approach was used to capture heat retention characteristics and subsequent warm-up effects. A 1-D powertrain warm-up model was developed in GT-Suite to capture the thermal warm-up characteristics of the powertrain. The model included a temperature dependent friction model, the themal-hydraulic characteristics of the cooling and lubrication circuits as well as parasitic losses associated with pumps.
Technical Paper

Development of the Defrost Performance Evaluation Technology in Automotive using Design Optimization Analysis Method

2020-04-14
2020-01-0155
In this study, we developed the defrost performance evaluation technology using the multi-objective optimization method based on the CFD. The defrosting is one of the key factors to ensure the drivers’ safety using the forced flow having proper temperature from HVAC during drive. There are many factors affecting the defrost performance, but the configurations of guide-vane and discharge angles in the center DEF duct section which are main design factors of the defrost performance in automotive, so these were set to the design parameters for this study. For the shape-optimization study, the discharge mass flow rate from the HVAC which is transferred to the windshield and the discharge areas in the center DEF duct were set to the response parameters. And then, the standard deviation value of mass flow rate on the selected discharge areas checking the uniformity of discharge flow was set to the objective function to find the optimal design.
Technical Paper

Transient Simulation of Heat Exchangers with Phase Change Material

2020-04-14
2020-01-0156
Heat exchangers with Phase Change Material (PCM) are finding more energy storage applications for both ICEs and EVs. These applications include cold storage evaporators for stop-start cars, thermal storage system for EV cabin heating and cooling, and other HVAC and PTC peak load shaving applications. The energy stored in PCM heat exchangers is typically charged/discharged using refrigerant or coolant, depending on the system design of different applications. Due to the low thermal conductivity of state-of-art PCM, the PCM heat exchangers generally rely on aluminum fins to enhance the speed of charging and discharging of the stored energy. Different fin shape, height, and fin density will result in different PCM freezing/melting rate.
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