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Towards High Accuracy Parking Slot Detection for Automated Valet Parking System

Tongji University-Qinghua Yang, Hui Chen, Junzhe Su, Jie Li
Published 2019-11-04 by SAE International in United States
Highly accurate parking slot detection methods are crucial for Automated Valet Parking (AVP) systems, to meet their demanding safety and functional requirements. While previous efforts have mostly focused on the algorithms’ capabilities to detect different types of slots under varying conditions, i.e. the detection rate, their accuracy has received little attention at this time. This paper highlights the importance of trustworthy slot detection methods, which address both the detection rate and the detection accuracy. To achieve this goal, an accurate slot detection method and a reliable ground-truth slot measurement method have been proposed in this paper. First, based on a 2D laser range finder, datapoints of obstacle vehicles on both sides of a slot have been collected and preprocessed. Second, the Density-Based Spatial Clustering of Applications with Noise (DBSCAN) algorithm has been improved to efficiently cluster these unevenly-distributed datapoints. After that, the Random Sample Consensus (RANSAC) algorithm has been improved to accurately fit the vehicles’ longitudinal contours. Finally, the candidate slot has been constructed and checked for its rationality. The final slot detection results have…
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Adaptive Design of Driver Steering Override Characteristics for LKAS

JTEKT Corporation-Yosuke Nishimura, Atsushi Ishihara, Kazuya Ando
Tongji University-Quyi Liu, Hui Chen, Jiachen Chen
Published 2019-11-04 by SAE International in United States
Lane Keeping Assistance System (LKAS) is a typical lateral driver assistance system with low acceptance. One of the main reasons is that fixed parameters cannot satisfy individual differences. So LKAS adaptive to driver characteristics needs to be designed. Driver Steering Override (DSO) process is an important process of LKAS. It happens when contradiction between driver’s intention and system behavior occurs. As feeling of overriding will affect the overall experience of using LKAS, the design of DSO characteristics is worthy of attention. This research provided an adaptive design scheme aiming at DSO characteristics for LKAS by building Driver Preference Model (DPM) based on simulator test data from preliminary experiments. The DPM was to represent the relationship between driver characteristics indices and driver preferred system characteristics indices. So that new drivers’ preference can be predicted by DPM based on their own daily driving data with LKAS switched off. The inputs of DPMs are 27 lane changing driver characteristics indices which were extracted based on natural lane changing data. Principal Component Analysis (PCA) and correlation analysis were used…
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Study on Robust Motion Planning Method for Automatic Parking Assist System Based on Neural Network and Tree Search

Tongji University-Fengwei Hu, Hui Chen, Jiren Zhang
Published 2019-11-04 by SAE International in United States
Automatic Parking Assist System (APAS) is an important part of Advanced Driver Assistance System (ADAS). It frees drivers from the burden of maneuvering a vehicle into a narrow parking space. This paper deals with the motion planning, a key issue of APAS, for vehicles in automatic parking. Planning module should guarantee the robustness to various initial postures and ensure that the vehicle is parked symmetrically in the center of the parking slot. However, current planning methods can’t meet both requirements well. To meet the aforementioned requirements, a method combining neural network and Monte-Carlo Tree Search (MCTS) is adopted in this work. From a driver’s perspective, different initial postures imply different parking strategies. In order to achieve the robustness to diverse initial postures, a natural idea is to train a model that can learn various strategies. As artificial neural network has outstanding potential in representing and learning knowledge, a neural network is utilized to provide prior knowledge, which is trained through supervised learning by a novel method that imitates human learning style. However, the training accuracy…
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Evaluation and Optimization of Driver Steering Override Strategy for LKAS Based on Driver’s Acceptability

JTEKT Corporation-Yosuke Nishimura, Kazuya Ando
Tongji University-Xiaolin He, Hui Chen, Jiachen Chen, Wei Ran
Published 2018-08-07 by SAE International in United States
In order to satisfy design requirements of Lane Keeping Assistance System (LKAS), a Driver Steering Override (DSO) strategy is necessary for driver’s interaction with the assistance system. The assistance system can be overridden by the strategy in case of lane change, obstacle avoidance and other emergency situations. However, evaluation and optimization of the DSO strategy for LKAS cannot easily be completed quantitatively considering driver’s acceptability. In this research, firstly subjective and objective evaluation experiment is designed. Secondly, correlations between the subjective and the objective evaluation results are established by using regression analysis. Finally, based on the correlations established previously, the optimal performance of DSO strategy is obtained by setting the desired comprehensive evaluation ratings as the optimized goal. Except for the whole process of the research, there are some details of the subjective and objective evaluation experiment design to be introduced. For the objective evaluation experiment, several objective characteristic indices (CI) are extracted, which are unrelated to controller. As for the subjective evaluation experiment, a questionnaire consisting of 7 questions is initially designed. Then, based…
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Study on Important Indices Related to Driver Feelings for LKA Intervention Process

JTEKT Corporation-Yosuke Nishimura, Kazuya Ando
Tongji University-Bin Zhong, Hui Chen, Jiachen Chen, Xiaoming Lan, Quyi Liu
Published 2018-08-07 by SAE International in United States
Lane Keeping Assistance (LKA) system is a very important part in Advanced Driver Assistance Systems (ADAS). It prevents a vehicle from departing out of the lane by exerting intervention. But an inappropriate performance during LKA intervention makes driver feel uncomfortable. The intervention of LKA can be divided into 3 parts: intervention timing, intervention process and intervention ending. Many researches have studied about the intervention timing and ending, but factors during intervention process also affect driver feelings a lot, such as yaw rate and steering wheel velocity. To increase driver’s acceptance of LKA, objective and subjective tests were designed and conducted to explore important indices which are highly correlated with the driver feelings.Different kinds of LKA controller control intervention process in different ways. Therefore, it’s very important to describe the intervention process uniformly and objectively. This paper proposes 16 Characteristic Indices (CI), such as ‘maximum yaw rate’, to describe steering wheel motion, vehicle motion and other aspects during variable LKA intervention processes. Then, to acquire drivers’ subjective evaluation about LKA, a questionnaire including 3 questions from…
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Driver Lane Keeping Characteristic Indices for Personalized Lane Keeping Assistance System

JTEKT Corporation-Yosuke Nishimura, Kazuya Ando, Kei Kitahara
Tongji University-Xiaoming Lan, Hui Chen, Xiaolin He, Jiachen Chen
Published 2017-09-23 by SAE International in United States
In the recent years, the interaction between human driver and Advanced Driver Assistance System (ADAS) has gradually aroused people’s concern. As a result, the concept of personalized ADAS is being put forward. As an important system of ADAS, Lane Keeping Assistance System (LKAS) also attracts great attention. To achieve personalized LKAS, driver lane keeping characteristic (DLKC) indices which could distinguish different driver lane keeping behavior should be researched. However, there are few researches on DLKC indices for personalized LKAS. Although there are many researches on modeling driver steering behavior, these researches are not sufficient to obtain DLKC indices. One reason is that most of researches are for double lane change behavior which is different from driver lane keeping behavior. The other reason is that the researches on driver lane keeping behavior only provide model structure and rarely discuss identification procedure such as how to select suitable data. Besides, these researches ignore the relationship between driver behavior and the design of personalized LKAS. In this paper, DLKC indices for personalized LKAS are comprehensively researched. Firstly, DLKC…
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Longitudinal Planning and Control Method for Autonomous Vehicles Based on A New Potential Field Model

Tongji University-Yandong Ruan, Hui Chen, Jiancong Li
Published 2017-09-23 by SAE International in United States
An integrated automatic driving system consists of perception, planning and control. As one of the key components of an autonomous driving system, the longitudinal planning module guides the vehicle to accelerate or decelerate automatically on the roads. A complete longitudinal planning module is supposed to consider the flexibility to various scenarios and multi-objective optimization including safety, comfort and efficiency. However, most of the current longitudinal planning methods can not meet all the requirements above. In order to satisfy the demands mentioned above, a new Potential Field (PF) based longitudinal planning method is presented in this paper. Firstly, a PF model is constructed to depict the potential risk of surrounding traffic entities, including obstacles and roads. The shape of each potential field is closely related to the property of the corresponding traffic entity. Secondly, a high-level controller and a low-level controller for the longitudinal motion are respectively designed to realize functions of the longitudinal planning and control. Based on the PF model, the longitudinal high-level controller can calculate the desired acceleration by optimizing a cost function…
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Study on Path Following Control Method for Automatic Parking System Based on LQR

SAE International Journal of Passenger Cars - Electronic and Electrical Systems

Tongji University-Zhengshuai Fan, Hui Chen
  • Journal Article
  • 2016-01-1881
Published 2016-09-14 by SAE International in United States
The Automatic Parking System (APS) is consisted of environmental perception, path planning and path following. As one of the key technologies in APS, path following module controls the lateral movement of the vehicle during the parking process. A mature path following module should meet all the performance indexes of high precision, fast convergence, convenient tuning and good passenger comfort. However, the current path following control methods can only meet parts of the performance indexes, instead of all. In order to satisfy all the performance indexes above, a path following control method based on Linear Quadratic Regulator (LQR) is proposed in this paper. Firstly, the linearization of the non-linear vehicle kinematic model was done to establish a linear system of the path following error. Secondly, LQR optimal control was used to achieve the closed-loop control of this linear system to guarantee its stability and fast convergence property. In this process, optimal quadratic performance index of LQR can be achieved by balancing the weights of the state variables and inputs through the matrix Q and R. For…
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An ADAS-Oriented Virtual EPS Platform Based on the Force Feedback Actuator of the Steer-by-Wire System

Tongji University-Gaoming Fang, Hui Chen
Published 2016-09-14 by SAE International in United States
Electric Power Steering (EPS) is the actuator of several lateral-dynamic-related Advanced Driver Assistance Systems (ADAS). A driving simulator with EPS will be much helpful for the ADAS development. However, if a real EPS is used in the driving simulator, it is quite difficult to realize the road reaction force accurately and responsively. To overcome this weakness, a virtual EPS platform is established. The virtual EPS platform contains two parts: one is the vehicle and EPS model, the other is the force feedback actuator (FFA) of the Steer-by-Wire (SBW) system. The FFA is an interface between the driver and the EPS/vehicle model. The reactive torque of the FFA is obtained based on the models. Meanwhile, the input of the EPS model is the steering angle of the FFA. Comparing to a real EPS, the virtual EPS platform has a problem of instability because of the actuator lag of the FFA. Therefore, a damping control method is applied to make the system stable. In addition, to make the steering characteristic of the FFA the same to that…
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A Potential Field Based Lateral Planning Method for Autonomous Vehicles

SAE International Journal of Passenger Cars - Electronic and Electrical Systems

Tongji University-Qiang Tu, Hui Chen, Jiancong Li
  • Journal Article
  • 2016-01-1874
Published 2016-09-14 by SAE International in United States
As one of the key technologies in autonomous driving, the lateral planning module guides the lateral movement during the driving process. An integrated lateral planning module should consider the non-holonomic constraints of a vehicle, the optimization of the generated trajectory and the applicability to various scenarios. However, the current lateral planning methods can only meet parts of these requirements. In order to satisfy all the performance requirements above, a novel Potential Field (PF) based lateral planning method is proposed in this paper. Firstly, a PF model is built to describe the potential risk of the traffic entities, including the obstacles, road boundaries and lines. The potential fields of these traffic entities are determined by their properties and the traffic regulations. Secondly, the planning algorithm is presented, which comprises three modules: state prediction, state search and trajectory generation. The state prediction is realized through the lateral dynamics and kinematics equations of the vehicle. Then based on the PF model, a cost function is designed, which takes the potential risk and comfort requirements into consideration. With the…
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