Research on Active Safety Methodologies for Intelligent Railway Systems

Safety is essential when building a strong transportation system.As a key development direction in the global railway system,the intelligent railway has safety at its core,making safety a top priority while pursuing the goals of efficiency,convenience,economy,and environmental friendliness.This paper describes the state of the art and proposes a system architecture for intelligent railway systems.It also focuses on the development of railway safety technology at home and abroad,and proposes the active safety method and technology system based on advanced theoretical methods such as the in-depth integration of cyber–physical systems(CPS),data-driven models,and intelligent computing.Finally,several typical applications are demonstrated to verify the advancement and feasibility of active safety technology in intelligent railway systems.

HPR1000： Advanced Pressurized Water Reactor with Active and Passive Safety

HPR1000 is an advanced nuclear power plant(NPP)with the significant feature of an active and passive safety design philosophy,developed by the China National Nuclear Corporation.On one hand,it is an evolutionary design based on proven technology of the existing pressurized water reactor NPP;on the other hand,it incorporates advanced design features including a 177-fuel-assembly core loaded with CF3 fuel assemblies,active and passive safety systems,comprehensive severe accident prevention and mitigation measures,enhanced protection against external events,and improved emergency response capability.Extensive verification experiments and tests have been performed for critical innovative improvements on passive systems,the reactor core,and the main equipment.The design of HPR1000fulfills the international utility requirements for advanced light water reactors and the latest nuclear safety requirements,and addresses the safety issues relevant to the Fukushima accident.Along with its outstanding safety and economy,HPR1000 provides an excellent and practicable solution for both domestic and international nuclear power markets.

Chassis Coordinated Control for Full X-by-Wire Vehicles-A Review

An X-by-wire chassis can improve the kinematic characteristics of human-vehicle closed-loop system and thus active safety especially under emergency scenarios via enabling chassis coordinated control.This paper aims to provide a complete and systematic survey on chassis coordinated control methods for full X-by-wire vehicles,with the primary goal of summarizing recent reserch advancements and stimulating innovative thoughts.Driving condition identification including driver’s operation intention,critical vehicle states and road adhesion condition and integrated control of X-by-wire chassis subsystems constitute the main framework of a chassis coordinated control scheme.Under steering and braking maneuvers,different driving condition identification methods are described in this paper.These are the trigger conditions and the basis for the implementation of chassis coordinated control.For the vehicles equipped with steering-by-wire,braking-by-wire and/or wire-controlled-suspension systems,state-of-the-art chassis coordinated control methods are reviewed including the coordination of any two or three chassis subsystems.Finally,the development trends are discussed.

Post-Impact Motion Planning and Tracking Control for Autonomous Vehicles

There is an increasing awareness of the need to reduce traffic accidents and fatality due to vehicle collision.Post-impact hazards can be more serious as the driver may fail to maintain effective control after collisions.To avoid subsequent crash events and to stabilize the vehicle,this paper proposes a post-impact motion planning and stability control method for autonomous vehicles.An enabling motion planning method is proposed for post-impact situations by combining the polynomial curve and artificial potential field while considering obstacle avoidance.A hierarchical controller that consists of an upper and a lower controller is then developed to track the planned motion.In the upper controller,a time-varying linear quadratic regulator is presented to calculate the desired generalized forces.In the lower controller,a nonlinear-optimization-based torque allocation algorithm is proposed to optimally coordinate the actuators to realize the desired generalized forces.The proposed scheme is verified under comprehensive driving scenarios through hardware-in-loop tests.

Micro-behavior Analysis of Pilots Based on Human-Aircraft-Environment Interaction

Micro-behavior of pilots is one of the most remarkable aspects in flight safety research domain.The study of pilot’s micro-behavior and its function are of great significance to enhance active safety warnings of flight and evaluation of flight cadets.Based on the cognitive process of pilots,this paper explores the meanings and contents of previous research on the pilot’s micro-behavior.The history and research status of pilot’s micro-behavior are briefly introduced from the perspective of their psychology,physiology and physics.The current reviews mainly include the pilot’s characteristic,multi-information fusion,integrated cognitive and humanization about controlling environment,etc.The several methods of these studies are discussed,and the mechanisms,experimental contents and applicable conditions of pilot’s physiological,psychological and physical characteristics are analyzed.Meanwhile,the advantages and shortcomings of the existing research results are pointed out and analyzed.Combined with flight simulation experiment,the internal mechanism of pilot is explained.Furthermore,with the latest research in the modern flight field,and also from the specialization of application,the diversification of methodologies and the depth of investigation are provided,as well as the development trend of pilot’s micro-behavior analysis in the future.

Longitudinal speed control algorithm to improve the vehicle stability and mobility on a sharp curve

A new longitudinal speed control strategy is proposed. It used the lateral jerk information as the feedback to predict the longitudinal acceleration and deceleration, which is especially beneficial to a sharp curve turning at a high driving speed. The performance of the controller is validated with Matlab/Simulink. The simulation results indicate that compared with the traditional vehicle, the G-vector controller can reduce the turning radius and improve the vehicle stability and agility obviously. And the proposed longitudinal speed control strategy could trade-off the longitudinal and lateral acceleration by using the tire force during the turning.

Investigation of Braking Timing of Drivers for Design of Pedestrian Collision Avoidance System

The braking behavior of drivers when a pedestrian comes out from the sidewalk to the road was analyzed using a driving simulator. Based on drivers＇ braking behavior, the braking control timing of the system for avoiding the collision with pedestrians was proposed. In this study, the subject drivers started braking at almost the same time in terms of TTC （Time to Collision）, regardless of the velocity of a subject vehicle and crossing velocity of pedestrians. This experimental result showed that brake timing of the system which can minimize the interference for braking between drivers and the system is 1.3 s of TTC. Next, the drivers＇ braking behavior was investigated when the system controlled braking to avoid collision at this timing. As a result, drivers did not show any change of braking behavior with no excessive interference between braking control by the system and braking operation by drivers for avoiding collisions with pedestrians which is equivalent to the excessive dependence on the system.

Human Body Behavior as Response on Autonomous Maneuvers, Based on ATD and Human Model

In the near future, active safety systems will take more control over the vehicle driving, even up to introducing fully autonomous vehicles. Nowadays, it is expected that the active safety systems will aid avoiding collisions much more efficiently than human drivers. These systems can protect not only the passengers, but also other road users. To mitigate collision, certain maneuvers （e.g., sudden braking, lane change, etc.） need to be done in a reasonably quick time. However, this may lead to low-g energy pulses. The latter fact, may cause unexpected and, in some cases, unwanted occupant body motion resulting even in OOP （out of position） postures. New patterns of occupant reactions in such cases are, to some extent, confirmed experimentally [1-3]. This paper evaluates the limits of standard ATDs （anthropometric test devices） and chosen human models in well established maneuver scenarios. Obtained results are compared with experimental data available in the literature. Drawbacks identify new challenges for the near future simulation based safety engineering. One scenario with combined conditions of emergency braking during lane change has been used as an example of OOP posture after maneuver.

Overview of Vehicle AEB

With the rapid development of China's economy and the continuous improvement of people's living standards,people pay more attention to the safety of cars.China's car sales and ownership is also rising,but also led to a lot of traffic accidents.With the continuous promotion of intelligent,electric and networked automobiles,Autonomous Emergency Braking system has become the focus of automobile enterprises in the active safety of automobiles.The overall scheme of auto emergency braking includes information acquisition module,control module and execution module.This paper briefly introduces the application status of this field at home and abroad,and discusses the function and implementation method of each module respectively.

Simulation and Analysis on Overtaking Safety Assistance System Based on Vehicle-to-Vehicle Communication

Because of the complexity and variability of an intelligent vehicle’s driving environment,it is difficult for the application of the vehicular sensors to meet the needs of the surrounding environment information entirely.Vehicle-to-vehicle(V2V)communication technology is used by target vehicles to exchange information,and obtain the driving condition and driving intention of the front driver.To obtain environmental information outside the range of vehicular sensors in advance,in this paper,a vehicle overtaking assistance system is proposed based on V2V communication.The data,including the speed,position,direction angle and steering angle obtained using V2V communication,were preliminarily processed.Then,combined with an overtaking safety distance model,the vehicle parameters,driver’s driving intention and vehicle status information were entered into an overtaking security assistance system to determine the overtaking conditions.Fuzzy theory was used to control the parameters of the overtaking safety distance model.Finally,the overtaking safety assistance system was established and the proposed algorithm was tested using PreScan/MATLAB cooperative simulation software.The results showed that the proposed overtaking safety algorithm effectively provided a warning according to environmental change and the driver’s intention,which assisted the driver to overtake and avoid the occurrence of accidents,which improved the safety performance of the vehicle.

A road hypnosis identification method for drivers based on fusion of biological characteristics

Risky driving behaviors,such as driving fatigue and distraction have recently received more attention.There is also much research about driving styles,driving emotions,older drivers,drugged driving,DUI(driving under the influence),and DWI(driving while intoxicated).Road hypnosis is a special behavior significantly impacting traffic safety.However,there is little research on this phenomenon.Road hypnosis,as an unconscious state,is can frequently occur while driving,particularly in highly predictable,monotonous,and familiar environments.In this paper,vehicle and virtual driving experiments are designed to collect the biological characteristics including eye movement and bioelectric parameters.Typical scenes in tunnels and highways are used as experimental scenes.LSTM(Long Short-Term Memory)and KNN(K-Nearest Neighbor)are employed as the base learners,while SVM(Support Vector Machine)serves as the meta-learner.A road hypnosis identification model is proposed based on ensemble learning,which integrates bioelectric and eye movement characteristics.The proposed model has good identification performance,as seen from the experimental results.In this study,alternative methods and technical support are provided for real-time and accurate identification of road hypnosis.

CHINESE MANDATORY STANDARDS ON AUTO ACTIVE SAFETY

The Law of Standardization promulgated in 1988 divides the standards into two types: mandatory and recommended, and it stipulates clearly that the production and sale of products shall satisfy the requirements raised in the mandatory standards.

Estimation of vehicle states and tire-road friction using parallel extended Kalman filtering

A model-based estimator design and implementation is described in this paper to undertake combined estimation of vehicle states and tire-road friction coefficients.The estimator is designed based on a vehicle model with three degrees of freedom(3-DOF) and the dual extended Kalman filter(DEKF) technique is employed.Effectiveness of the estimation is examined and validated by comparing the outputs of the estimator with the responses of the vehicle model in CarSim in three typical road adhesion conditions(high-friction,low-friction,and joint-friction roads).Simulation results demonstrate that the DEKF estimator algorithm designed is able to obtain vehicle states(e.g.,yaw rate and roll angle) as well as road friction coefficients with reasonable accuracy.

Evaluation of the Effectiveness of Awareness Messages for Road Traffic Hazards in Experimental Tests

Advanced driver assistance systems, especially autonomous emergency braking and forward collision warnings, have becomepopular in Japan. To reduce the number of road traffic accidents, safety information should be provided to a driver earlier thanavoidance or warning messages so as to avoid a risky situation. A series of actual running tests was conducted to evaluate theactivation timing and effectiveness of awareness messages. Objective analysis showed that the drivers could avoid an obstaclewith a sufficient safety margin thanks to any of the awareness messages. Subjective ratings showed that the best timing is 10 sbefore encountering the obstacle. The results of objective analysis are limited in the present paper, and further analyses arerequired.

Research on Driver Fatigue Early Warning Method Based on ARM

Fatigue driving is one of the important reasons of road traffic accidents, fatigue driving is refers to the driver in a long time continuous driving or physical fatigue condition, and then come into being physiological and psychological function disorder. In order to overcome the limitation of single sensor in the fatigue test, aimed at the requirements of monitoring on the fatigue driving, this article designed an driver fatigue monitor system based ARM926EJ-S as a controller, it is used to determine the driver＇s fatigue and reduce the traffic accident. On the basis of fully considering the source correlation and complementary, it adopts the method of multi-source information fusion; by monitoring the pulse, heart rate, temperature of the human body, steering wheel grip strength to realized the fatigue level. The system of graphical interface adopts UCGUI. Finally, testing the main function modules of early warning system, the feasibility of the proposed early warning system is verified fusion .