Active Safety Systems Research Articles

Simulation of a Station Blackout Accident for the SMART Using the CINEMA Code

SMART is a small-sized integral type PWR containing major components within a single reactor pressure vessel. Advanced design features implemented into SMART have been proven or qualified through experience, testing, or analysis according to the applicable approved standards. After Fukushima accident, a rising attention is posed on the strategy to cope with a Station Blackout (SBO) accident, which is one of the representative severe accidents related to the nuclear power plants. The SBO is initiated by a loss of all offsite power with a concurrent failure of both emergency diesel generators. With no alternate current power source, most of the active safety systems that perform safety functions are not available. The purpose of SBO analysis in this paper is to show that the integrity of the containment can be maintained during a SBO accident in the SMART (System-integrated Modular Advanced ReacTor). Therefore, the accident sequence during a SBO accident was simulated using the CINEMA-SMART (Code for INtegrated severe accidEnt Management and Analysis-SMART) code to evaluate the transient scenario inside the reactor vessel after an initiating event, core heating and melting by core uncovery, relocation of debris, reactor vessel failure, discharge of molten core, and pressurization of the containment. It is shown that the integrity of the containment can be maintained during a SBO accident in the SMART reactor. It has to be mentioned that the assumptions used in this analysis are extremely conservative that the passive safety systems of PSIS and PRHRS were not credited. In addition, as ANS73 decay heat with 1.2 multiplier was used in this analysis, actual progression of the accident would be much slow and amount of hydrogen generation will be much less.

Active Safety System for Urban Environments with Detecting Harmful Pedestrian Movement Patterns Using Computational Intelligence

This article presents a system for detecting pedestrian movement patterns in urban environments, by applying computational intelligence methods for image processing and pattern detection. The proposed system is capable of processing multiple images and video sources in real-time. Furthermore, it has a flexible design, as it is based on a pipes and filters architecture that makes it easy to evaluate different computational intelligence techniques to address the subproblems involved in each stage of the process. Two main stages are implemented in the proposed system: the first stage is in charge of extracting relevant features of the processed images, by applying image processing and object tracking, and the second stage is responsible for the patterns detection. The experimental analysis of the proposed system was performed over more than 1450 problem instances, using PETS09-S2L1 videos, and the results were compared with part of the Multiple Object Tracking Challenge benchmark results. Experiments covered the two main stages of the system. Results indicate that the proposed system is competitive yet simpler than other similar software methods. Overall, this article provides the theoretical frame and a proof of concept needed for the implementation of a real-time system that takes as input a group of image sequences, extracts relevant features, and detects a set of predefined patterns. The proposed implementation is a reliable proof of the viability of building pedestrian movement pattern detection systems.

Experimental Analysis on Safety System of a Simulated Small Scale Pressurized Water Reactor System with Intelligent Control

Reactors are widely used in the nuclear power plant due to the rapid demand for electricity by reducing the greenhouse effect. However, the effectiveness of the nuclear reactor depends on an adequate safety system. Hence, temperature and heat transfer are two critical parameters for any reactor in operation for which intelligent temperature control with an integrated safety system is essential. Therefore, the present study has emphasized the development of a simulated small-scale water-based reactor with intelligent control and safety system and examined through the analysis of thermal-hydraulic parameters. Radial heat transfer of an electric rod used as fuel in the primary circuit has been analyzed by taking sensor reading in various positions of the core. The developed system is self-controlled with all possible active and passive safety systems. Consecutively, the prototype has also been designed including manual adjustment to ensure a fail-safe environment. The system is capable to operate at temperatures between 80°C and 120°C, although the design can withstand up to 200°C. The data of the experiment are taken under the pressure of 200 kPa at 120°C temperature. Results show that heat output of 2116.09 kJ has been obtained from the system against heat input of 2514.80 kJ, which gives an efficiency around 16% of the developed system.

Experimental Platform for Evaluation of On-Board Real-Time Motion Controllers for Electric Vehicles

Electric vehicles are considered to be a greener and safer means of transport thanks to the distinguished advantages of electric motors. Studies on this object require experimental platforms for control validation purpose. Under the pressure of research, the development of these platforms must be reliable, safe, fast, and cost effective. To practically validate the control system, the controllers should be implemented in an on-board micro-controller platform; whereas, the vehicle model should be realized in a real-time emulator that behaves like the real vehicle. In this paper, we propose a signal hardware-in-the-loop simulation system for electric vehicles that are driven by four independent electric motors installed in wheels (in-wheel motor). The system is elaborately built on the basis of longitudinal, lateral, and yaw dynamics, as well as kinematic and position models, of which the characteristics are complete and comprehensive. The performance of the signal hardware-in-the-loop system is evaluated by various open-loop testing scenarios and by validation of a representative closed-loop optimal force distribution control. The proposed system can be applied for researches on active safety system of electric vehicles, including traction, braking control, force/torque distribution strategy, and electronic stability program.

Research of fatal car-to-pedestrian precrash scenarios for the testing of the active safety system in China

Road safety remains a challenge with numerous Vulnerable Road Users (VRUs) suffering from injuries and death every year. Pedestrian protection using active safety systems, such as Automated Emergency Braking (AEB), is an effective measure to combat the situation. Furthermore, the perception of precrash scenarios plays an important role in active safety research. It is essential to understand and define precrash scenarios. This study aimed to apply the obtained typical car-to-pedestrian precrash scenarios from Chinese severely injured pedestrian traffic accidents to develop and test active safety systems. The National Automobile Accident In-Depth Investigation System (NAIS) recorded 467 cases from 2011 to 2018 in China, and 12 items were selected from the NAIS database as description variables for the precrash scenario. The items were divided into four categories: car, pedestrian, road, and environment. Group decision theory was applied to evaluate the importance of each variable in its category. A total of 34 basic scenarios were defined and obtained according to the extracted significant variables. These basic scenarios represented diverse fatal scenarios in China which are crucial for autonomous driving. The frequency distribution of the scenarios demonstrated that the top five scenarios covered 85.3 % of the total. Five scenarios were identified to have the common characteristic of cars going straight. Additionally, 13 detailed scenarios were obtained from the five basic scenarios by using cluster and frequency analyses. In contrast to the New Car Assessment Program (NCAP) test scenarios, weather and lighting conditions were considered in these 13 scenarios, and the driving speed before the crash were mostly distributed in the range of 40–80 km/h (20–60 km/h in the NCAP). Meanwhile, both walking and running were commonly recorded for pedestrians to cross the street from the nearside, compared with records of walking only to cross from the nearside in the NCAP. These results contribute to a reference for test scenarios of pedestrian AEB or Forward Collision Warning (FCW) in China.

Theoretical and experimental possibilities to set up some sensors systems involved in active safety process

The safety systems present in the construction of modern motor vehicles fully benefit from all development research efforts in the field of autonomous motor vehicles. In this paper, we have analyzed, theoretically and experimentally, for three distinct types of passenger cars, the following active safety systems: 1. Autonomous Emergency Braking system, designed as an automatic braking process of the vehicle, in response to the detection of a probable collision, to reduce the speed of the vehicle; 2. Forward Collision Warning, implemented as an audiovisual warning that is present on board a motor vehicle, to alert the driver; 3. Dynamic Brake support, which further amplifies the braking force to detect the imminent collision to achieve a higher deceleration than in the situation of a normal speed reduction. As a following were study three states such as: Car-to-Car Rear Stationary as a possible collision in which a vehicle travels forwards towards another stationary vehicle and the front structure of the vehicle strikes the rear structure of the other, Car-to-Car Rear Moving as a probable collision in which a vehicle travels forwards towards another vehicle that is travelling at constant speed and the front structure of the vehicle strikes the rear structure of the other and possible collisions named Car-to-Car Rear Braking in which a vehicle travels forwards towards another vehicle that is travelling at constant speed and then decelerates, and the frontal structure of the vehicle strikes the rear structure of the other. The three situations have been examined, experimentally and theoretic, in order to obtain important information about the configurations of sensor systems that compose safety systems. The work allowed to obtain configuration information, experimentally confirmed, with an impact on the improvement of future autonomous vehicles system.

Numerical simulation of the crush behavior of tapered tubes

Abstract Traffic accidents are increasing as a result of an increasing number of vehicles and population growth in recent years. Active and passive safety systems are used in the vehicles we use today to reduce traffic accidents and prevent casualties. One of the passive security systems is the crush box (crashworthiness). It absorbs the energy generated during a crash by plastic deformation. In this study, tube height, diameter and thickness parameters were kept constant and degrees of conicity were varied 0°(flat tube),3°,7°,10°,12° and 15° The effects of conical crush boxes on axial crush behavior and their energy absorption ability, were investigated by Ls-Dyna explicit dynamic software.

Numerical simulation of the crush behavior of tapered tubes

Abstract Traffic accidents are increasing as a result of an increasing number of vehicles and population growth in recent years. Active and passive safety systems are used in the vehicles we use today to reduce traffic accidents and prevent casualties. One of the passive security systems is the crush box (crashworthiness). It absorbs the energy generated during a crash by plastic deformation. In this study, tube height, diameter and thickness parameters were kept constant and degrees of conicity were varied 0°(flat tube),3°,7°,10°,12° and 15° The effects of conical crush boxes on axial crush behavior and their energy absorption ability, were investigated by Ls-Dyna explicit dynamic software.

Radar Accuracy Modeling and Its Application to Object Vehicle Tracking

For advanced active safety systems and autonomous vehicles, it is essential to predict target vehicle behaviors. Radar is a reliable vehicular sensor, but it has a degree of measurement uncertainty because of its operational mechanism and wandering reflection point. To deal with this problem, this paper proposes a radar accuracy model for object vehicle tracking to reduce the tracking error of the radar system. First, we divide the area uniformly and identify the surrounding vehicles using information, including relative position and relative velocity.We then analyze the error characteristics of each uniformly divided area. Next, we develop an occupancy zone-based Kalman filter for each area based on the error characteristics. We solve the problem that one cannot assign an exact zone for the object vehicle due to radar error by using interacting multiple model (IMM) filter. The performance of the proposed method is validated via experiments using radar and ground truth data.

Design and Development of Variable overhang chassis mechanism

This mechanism is designed in such some way that the vehicle can have safe, simple and stable mobility even at the higher speeds. To confirm that the overhang is safe and secure while expansion and retraction positions. This mechanism will be powered by hydraulics and electronics by functionality. As this mechanism only be used for electric vehicles, it brings a modern approach for utilizing the massive existing space in the electric vehicle and proving additional safety to the vehicle This concept of the variable overhang mechanism also provides a new approach in designing the vehicle of future as the frontal crumple zone will be expanded and retracted in accordance to the speed variation. This system will be acting as an active safety system providing different configurations in adjustment to the road conditions and speed variations. Among the major road crashes which occurs in our day to day lives, most of those crashes are notes as head on collision. The current safety systems such as seatbelts and airbags perform a good job in safeguarding a person from upcoming injuries but despite of them we still require an additional system which will further improve the current safety conditions. This design will function by variable overhang mechanism which will further be helpful in crash reduction and will support vehicle as an added safety. In addition to this, it will support vehicle as a safety component by the introduction of honeycomb bumper, which will further sustain the impact and would be a great tool of utility. The honeycomb bumper will help sustaining the initial impact of the vehicle over crashes. This will result in drastic impact reduction at cabin area and improvising the safety conditions for the vehicle and certainly limit the impact transfer to the passenger cabin area. This safety feature will work on the principle of crumple zone, where the front mechanism of the vehicle will act as the frontal crumple zone to the vehicle by its self-breakdown tendency.

Evaluating Model Predictive Path Following and Yaw Stability Controllers for Over-Actuated Autonomous Electric Vehicles

Active safety systems are of significant importance for autonomous vehicles operating in safety-critical situations like an obstacle-avoidance manoeuvre with high vehicle speed or poor road condition. However, a conventional electronic stability control system, may not always yield desired path following and yaw stability performance in such circumstances merely through brake intervention. This paper pursues a detailed investigation on utilising model predictive control (MPC) and torque vectoring for path following and yaw stability control of over-actuated autonomous electric vehicles (AEVs) in dangerous double lane change manoeuvre. The control problem of the AEV is formulated based on MPC by utilising active front steering and torque vectoring, and constraints are imposed explicitly on yaw rate and sideslip angle to ensure yaw stability. Four MPC-based controllers are designed based on double-track vehicle models. Specifically, they include two one-level controllers, i.e. one with torque vectoring and one with equal torque allocation, and two two-level controllers, i.e. one with optimisation-based torque allocation and one with rule-based allocation. These controllers are assessed extensively, with respect to passing velocity, tracking accuracy, tyre utilisation and robustness. The effect of horizon length on the control performance and computational efficiency is also investigated.

An Augmentation Function for Active Pedestrian Safety System Based on Crash Risk Evaluation

This study proposed an augmentation function to current active pedestrian safety systems (APSSs), which is expected to be effective for pedestrian crashes caused by pedestrians’ unexpected behavior. The augmentation function estimates the crash risk with a pedestrian given its time-space-distance relationship with the pedestrian; the crash risk represents the probability of hitting that pedestrian given all the pedestrian's possible random trajectories in the near future. Once the crash risk exceeds a toleration threshold, the augmentation function activates evasive actions, even if there is no current conflict with the pedestrian. A Monte Carlo process was used to estimate the crash risk under different sets of vehicle and pedestrian kinematic features. The possible pedestrian trajectories were sampled from a fine-tuned Markovian integrated random walk model; in particular, kinematic variations between pedestrian types were considered. Then, the effectiveness of evasive actions was evaluated. It was found that children and young/middle-aged pedestrians require higher-intensity evasive actions in zones of moderate and severe crash risk; while old pedestrians need higher-intensity evasive actions in zones of mild crash risk. In addition, it is necessary to select proper speed reduction rate and combination of lane change and speed, to reduce the crash risk. Finally, the study demonstrated that a field of view of 50° and a detection range of 40 m would be the minimum requirement to support the augmentation function, which requires an upgrade for many automobile manufacturers’ current APSSs.

Structures active suspension for stabilizing vertical reactions of the road to the car wheels when driving over irregularities

The development of automotive technology is clearly characterized by the mass introduction of numerous active safety systems in the design of cars, such as anti-lock brakes, stability control systems, etc. In the conditions of a significantly increased number of motor transport, which is operated on roads of relatively low quality, the question of increasing the stability of the car when driving on uneven roads naturally arises. There are quite a lot of such roads in countries with large territories. There are numerous cases of the formation of sections with regular profiles on improved roads. Movement in such areas can cause resonant vibrations of unsprung masses, which, in turn, leads to a loss of stability of the vehicle. This article discusses the effectiveness of various structures of controlled suspensions that can be used in the stabilization system of vertical reactions of the road to the car wheels when driving on an uneven surface.

Influence of Tires Age on Vehicle's Braking Performance: a Case Study

Tires are one of the main components of active vehicle safety systems. The primary function of tires is to ensure the transmission of traction, torque, and braking forces to the road surface independently from weather conditions and vehicle speed. During the vehicle movement, tires should also offer an adequate level of comfort, stability, maneuverability, as well as a high degree of safety. From the point of active safety systems, tires have a substantial impact on different braking system parameters, especially the braking distance. When dealing with emergencies that require fast stopping of the vehicle, drivers need a minimum braking distance in order to avoid accidents. Data collected during the research shows that more than 32% of the vehicles in Kosovo use tires over six years old. In comparison, only about 11% of the vehicles are fitted with new tires. Multiple studies have pointed out that old and used tires can lead to an increase in the number of road accidents. This paper investigates the influence the tire age has on vehicle braking performance by analyzing parameters of the braking system such as average vehicle deceleration (MFDD), braking distance (Sf), and braking time (Tbr).

Addressed Fiber Bragg Structures in Load-Sensing Wheel Hub Bearings.

The work presents an approach to instrument the load-sensing bearings for automotive applications for estimation of the loads acting on the wheels. The system comprises fiber-optic sensors based on addressed fiber Bragg structures (AFBS) with two symmetrical phase shifts. A mathematical model for load–deformation relation is presented, and the AFBS interrogation principle is described. The simulation includes (i) modeling of vehicle dynamics in a split-mu braking test, during which the longitudinal wheel loads are obtained, (ii) the subsequent estimation of bearing outer ring deformation using a beam model with simply supported boundary conditions, (iii) the conversion of strain into central frequency shift of AFBS, and (iv) modeling of the beating signal at the photodetector. The simulation results show that the estimation error of the longitudinal wheel force from the strain data acquired from a single measurement point was 5.44% with a root-mean-square error of 113.64 N. A prototype load-sensing bearing was instrumented with a single AFBS sensor and mounted in a front right wheel hub of an experimental vehicle. The experimental setup demonstrated comparable results with the simulation during the braking test. The proposed system with load-sensing bearings is aimed at estimation of the loads acting on the wheels, which serve as input parameters for active safety systems, such as automatic braking, adaptive cruise control, or fully automated driving, in order to enhance their effectiveness and the safety of the vehicle.

Development and evaluation of potential accident scenarios involving pedestrians and AEB-equipped vehicles to demonstrate the efficiency of an enhanced open-source simulation framework

This study introduces a method that allows the generation and safety evaluation of a scenario catalog derived from potential car-pedestrian conflict situations. It is based on open-source software components and uses the road layout standard OpenDRIVE to derive participants’ motion profiles with the support of available accident data. The method was implemented upon the open-source framework openPASS and can simulate results for different active safety system setups and facilitates the prediction of system capabilities to decrease the relative impact velocities and collision configurations such as the point of impact. A demonstration case was performed where the scenario catalog was derived and used to evaluate pedestrian collisions with and without a generic autonomous emergency braking (AEB) system. The AEB system aims to intervene in the event of an impending collision and might affect the outcome of a baseline scenario. The study indicated a change in the collision configuration and identified conflict situations less affected by the system. A particularly interesting finding was that some scenarios even led to a higher number of collisions (at lower impact) for the AEB intervention in comparison to the baseline cases.

Modeling Drivers’ Strategy When Overtaking Cyclists in the Presence of Oncoming Traffic

Overtaking a cyclist on a two-lane rural road with oncoming traffic is a challenging task for any driver. Failing this task can lead to severe injuries or even death because of the potentially high impact speed in a possible collision. To avoid a rear-end collision with the cyclist, drivers need to make a timely and accurate decision about whether to steer and overtake the cyclist, or brake and let the oncoming traffic pass first. If this decision is delayed, for instance because the driver is distracted, neither braking nor steering may eventually keep the driver from crashing—at that point, rear-ending a cyclist may be the safest alternative for the driver. Active safety systems such as forward collision warning that help drivers being alert and avoiding collisions may be enhanced with driver models to reduce activations perceived as false positive. In this study, we developed a driver model based on logistic regression using data from a test-track experiment. The model can predict the probability and confidence of drivers braking and steering while approaching a cyclist during an overtaking, and therefore this model may improve collision warning systems. In both an in-sample and out-of-sample evaluation, the model identified drivers’ intent to overtake with high accuracy (0.99 and 0.90, respectively). The model can be integrated into a warning system that leverages the deviance of the actual driver behavior from the behavior predicted by the model to allow timely warnings without compromising driver acceptance.

New Phase of Motor Vehicle Development

Development of motor vehicles has gone through several technological phases and today we are definitely in a new era that is primarily related to steering autonomy and vehicle propulsion systems. Although electric vehicles have become an absolute priority in some countries, their global expansion is happening and it is to be expected that they will become a near future in these regions as well. Today, special attention is drawn to advances in the development of autonomous driving systems, which will cause many changes in design, regulations and the environment. For the coming wave of change, we need to be adequately prepared and take part in global processes. In addition, it should be noted that the futuristic versions of vehicles capable of moving in multiple environments, on land, on or in water and in the air, are being widely promoted, and the EU is introducing mandatory application of some active and passive safety systems.

Considering real-world sightline obstructions in crash and injury prevention estimates for left turn across path/opposite direction intersection active safety systems

Objective Previous analyses of active safety systems in left turn across path/opposite direction (LTAP/OD) crashes have shown that sensor sightline obstructions might affect the performance of these systems. National retrospective crash databases provide little information about the proportion of cases which have sightline obstructions. One promising alternative are naturalistic driving studies (NDS). The objective of this study was to estimate the proportion of LTAP/OD crashes and near-crashes which have sightline obstructions using a large-scale NDS and update previous estimates of intersection active safety system effectiveness using this information. Methods LTAP/OD crash and near-crash cases were identified from the Second Strategic Highway Research Program (SHRP 2) dataset. Each case was reviewed for the presence of obstructing vehicles when the left turning vehicle began turning. This study considered 241 crash and near-crash LTAP/OD events selected from SHRP 2. SHRP 2 was an NDS which collected 80 million kilometers of driving from approximately 2,500 participants over a 2.5 year period. The sightline obstruction ratio was defined as the proportion of cases which had sightline obstructions when the turning vehicle began turning. A logistic regression model was used to determine the statistical significance of factors which affected the sightline obstruction ratio, which included event severity, traffic control device, subject vehicle crash configuration, and turning lane presence. LTAP/OD active safety system effectiveness was quantified in a prior study for cases with and without sightline obstructions separately. System effectiveness was re-computed by weighting the results according to the worst-case sightline ratio computed in this study. Results Traffic control device, subject vehicle crash type (turning or traveling through), and turning lane presence were not found to affect sightline obstruction ratio. In crash cases, the sightline obstruction ratio was 40%. In near-crash cases, the sightline obstruction ratio was 18%. Finally, the effectiveness of an intersection active safety system was evaluated using this sightline obstruction ratio. Conclusions This study quantified the sightline obstruction ratio, an important parameter needed to evaluate intersection active safety systems. This study also establishes a baseline for evaluating the presence of sightline obstructions in a future naturalistic driving study when road infrastructure has changed.

DRIVES ALERT SYSTEM IN THE CONDITION OF INFORMATION SHORTAGE

The article presents the results of an accident analysis in the Russian Federation. Trends in reducing the number of accidents have been identified, but over the past 5 years the severity of their consequences has remained at a high level, despite the development of vehicles active and passive safety systems. A new accident prevention system is proposed by informing drivers about the occurrence of an emergency in conditions of insufficient and limited visibility, based on measuring the parameters of the vehicle movement in real time using GLONASS/GPS technologies.