Driver Braking Research Articles

Tradeoffs in the Evaluation of Light Vehicle Pre-Collision Systems

Pre-collision systems (PCS) use forward-looking sensors to detect the location and motion of vehicles ahead and provide a sequence of actions to help the driver either avoid striking the rear-end of another vehicle or mitigate the severity of the crash. The actions include driver alerts, amplification of driver braking as distance decreases (dynamic brake support, DBS), and automatic braking if the driver has not acted or has not acted sufficiently (crash imminent braking, CIB). Recent efforts by various organizations have sought to define PCS objective test procedures and test equipment in support of consumer information programs and potential certification. This paper presents results and insights from conducting DBS and CIB tests on two production vehicles sold in the US. Eleven scenarios are used to assess the systems' performance. The two systems' performance shows that commercial systems can be quite different. Also demonstrated is the experience with test equipment, including a towable target that has been designed for resiliency and radar signature, a braking robot, and bumper guard. While improvements continue in evaluation procedures, the community may still be a distance away from an ability to test these systems with realistic surrogate targets in speed conditions similar to those that lead to serious injury and fatalities. Recommendations are offered to help improve PCS evaluation. Language: en

Study on Regenerative Braking Control Algorithm

Based on the traditional hydraulic unit of ESC, Jilin University developed a braking energy recovery system of uniaxial decoupled. A first-order hysteresis filtering method with filtering time factor adaptively corrected was used to calculate driver's braking demand based on pressure of the master cylinder. A series of fixed partition coefficient control strategy was developed, coordinated control of electrical regenerative braking and hydraulic braking was carried out. Vehicle test was carried out. Vehicle test results show that the brake pedal travel simulator and the braking control strategies can improve the energy recovery, and ensure that the brake pedal feel is consistent with the traditional vehicle.

3211 衝突回避支援装置の効果分析手法(OS9-2 シミュレータによる評価,OS9 ビークルシミュレータの開発と応用,オーガナイズド・セッション(OS))

In this study, methodologies for estimating the accident mitigation ratio using the collision avoidance system are discussed. In these methodologies, the driver's braking or steering and viewing behavior are investigated in a driving simulator. Braking or steering behaviour was identified in terms of the reaction time for braking or steering in order to avoid a collision or lane deviation and viewing behaviour was identified in terms of the duration from looking off a leading vehicle to looking back. Next, to investigate the combined effect based on the reliability of driver and the reliability of system, two different kinds of reliability-estimation model simulating its operating status were constructed. The effectiveness of the system with different control setting can be quantitatively compared as the collision frequency or lane-deviation frequency calculated through time series Monte Carlo simulations or statistical calculations based on the reliability-estimation model.

Driver braking behaviour under near-crash scenarios

In this paper, we investigate driver braking behaviour under near-crash scenarios in one district of China. Real traffic scenarios were first collected using video drive recorder and these scenarios were screened and classified and then six typical types of near-crash scenarios were obtained. Then by processing the video images and analysing the velocity curves, driver braking behaviour under these six typical types of scenarios, especially the scenarios of ‘following vehicle approaching a decelerating lead vehicle’, was extracted and analysed. Finally, the driver brake reaction time, average deceleration during the emergency braking phase and the timing of emergency braking initiation were obtained. The results obtained in the paper can be used in the development of advanced driver assistance systems compatible with special Chinese traffic conditions.

The Analysis of the Key Problems about Traffic Accident Speed Identification Based on Braking Traces

In order to improve the impartiality and objectivity of judicial expertise, the key problems about traffic accident speed identification are analyzed and the speed of vehicle is calculated by using the braking performance test report with reference to the national standard and automobile theory. The automobile dynamics of driver braking process is analyzed, all kinds of key problems such as the braking distance, braking coordination time, braking speed, longitudinal sliding coefficient of adhesion are combined with the braking performance test report, and the method of determining the longitudinal sliding coefficient of adhesion is proposed, the instantaneous velocity before the collision is calculated. Finally, the method is used to calculate the speed of an actual case, and simulated in the software of PC-Crash, the results are consistent, verifying that the speed identification method is correct.

Braking Characteristics of Chinese Driver in Highway and Urban Road

To research Chinese driver's braking characteristics in highway and urban road, this paper carries out the field experiment, analyzes the braking reasons based on the inter-vehicle relationships, and research the distribution of THW and TTC when braking under different road types and braking reasons. First, the braking reasons are classified into three categories according to the various inter-vehicle relationships between the test vehicle and its leading vehicle, then the ratios of the braking categories are studied, finally the distribution of THW and TTC under different road types and braking reasons are analyzed by variance analysis and relevance analysis. The conclusions come out that the drivers tend to brake more in urban road especially when the leading vehicle brakes, the road types and braking reasons have a significant influence on THW compared with TTC, THW and TTC present an approximate linear relationship in urban road. The research results can support the design of the DAS such as Collision Avoidance System.

Driver-Related Delay in Emergency Braking Response to a Laterally Incurring Hazard

Collision analysis often assumes emergency deceleration begins immediately upon completion of the vehicle’s mechanical brake lag. The goal of this study is to determine the driver-related delay from initial brake application to various degrees of deceleration in a simulated emergency and to test variables contributing to the modulation of driver braking. Using the data of Mazzae et al (2003), in which drivers respond to a lateral vehicle incursion, we have assessed the contribution of Time-to-Intersection (TTI), road condition, gender and crash outcome on driver emergency brake response. In the first 0.3 second phase after initial brake application, vehicle behavior was similar across all variables as drivers reached only moderate levels of deceleration. In the second phase, drivers often took more than one second to reach emergency decelerations, especially with a longer TTI. Pavement condition, gender and crash outcome were not significant factors. We discuss the consequences of driver braking behavior in the context of driver feedback and accident reconstruction analyses.

J121016 予防安全効果評価シミュレータおけるドライバのブレーキ操作タイミングの決定方法

We are developing a simulation program called ASSESS (A Survey Simulator to Evaluate Safety Systems) which is intended to evaluate the effects of automotive prevention safety assistance systems. A simulated driver in the ASSESS drives a vehicle to avoid collisions with other vehicles. For the driver to drive safely, we need to determine the braking operation algorithm. The two decisive factors of braking operations here are the braking timing and the brake pedal force. In this paper, the former is discussed. After analyzing the previous experiment results about human cognitive judgments, we revealed that the timing of cognitive judgments is decided by the inverse of Time To Collision (iTTC), the inverse of distance, and the constant term. Based on this fact, we derived a formula to determine the driver's braking timing in the ASSESS.

Evaluating the Impact of Processing Spoken Words on Driving

The potential impact on driving of the processing of a single, auditorily presented word is analyzed in this work. Because driving is a complex cognitive activity that involves the integration and coordination of multiple subprocesses, the authors narrowed the scope of the research to concentrate on one critical task involved in driving: driver braking response. If two tasks have to be performed concurrently and both of them require access to a capacity-limited system, then performance in one or both of the tasks will dramatically worsen because the two processes will compete for access to cognitive resources. It has been shown that both word recognition and driving require central resources; therefore, these tasks are likely to interfere with each other. In the experiments, participants were required to perform two tasks during simulated driving. In the word recognition task, participants had to categorize auditorily presented words. In the braking task, participants depressed a brake pedal in response to the lead car's brake lights. The interval of time between the onset of the tasks’ stimuli was varied. Braking responses were substantially slower as the overlap between tasks increased. This finding demonstrates that the processing of a single word hinders driving performance. The experiments carried out have significant implications in the field of road safety. Many situations, such as cell phone ringing, cell phone conversations, auditory tips from navigation systems, and auditory alerts from driver warning systems, are similar to those studied. The experiments suggest that all these situations can negatively affect a driver's response time, increasing the likelihood of near misses and accidents.

Fuzzy Control Strategy and Simulation for Dual Electric Tracked Vehicle Motion Control

Based on tracked vehicle dynamics analysis, a fuzzy control strategy is proposed in this paper for the dual electric tracked vehicle motion control. The inputs of fuzzy system are driver acceleration, braking and steering signals besides vehicle velocity feedback signal, while outputs are dual motors’ torque commands and mechanical braker’s target force. Control strategy contains two fuzzy logics, one is for steering and straight-line running control, the other is for braking control section. Simulation results show that the fuzzy control strategy presented here is correct and effective for electric tracked vehicle motion control.

Effects and Evaluation of the Graded Deceleration Display on Driver Braking Performance

Driver braking performance is highly dependent on the driver's ability to estimate closing distance to the vehicle in front of them. Unfortunately, drivers often do not accurately perceive closing speed (Hoffman & Mortimer, 1996). Here, we examined whether providing graded deceleration magnitudes via an array of horizontally arranged brake lights (Graded Deceleration Display - GDD) can improve driver braking performance over standard (Binary) displays. In simulation, participants followed a lead vehicle through a series of braking events where the maximum rates of deceleration were systematically varied. Drivers were instructed to follow the lead vehicle at a safe and adequate distance. The Graded Deceleration Display resulted in slightly longer reaction times although the braking responses were more accurate in relation to the deceleration of the lead vehicle. The GDD also resulted in longer following distances, which could be indicative of an increased margin of safety for following vehicles. Language: en

Immobilisation of the knee and ankle and its impact on drivers’ braking times

The purpose of this study was to investigate the effects of right leg restriction at the knee, ankle or both, on a driver's braking times. Previous studies have not investigated the effects of knee restriction on braking performance. A total of 23 healthy drivers performed a series of emergency braking tests in a driving simulator in either an above-knee plaster cast, a below-knee cast, or in a knee brace with an increasing range of restriction. The study showed that total braking reaction time was significantly longer when wearing an above-knee plaster cast, a below-knee plaster cast or a knee brace fixed at 0°, compared with braking normally (p < 0.001). Increases in the time taken to move the foot from the accelerator to the brake accounted for some of the increase in the total braking reaction time. Unexpectedly, thinking time also increased with the level of restriction (p < 0.001). The increase in braking time with an above-knee plaster cast in this study would increase the stopping distance at 30 miles per hour by almost 3 m. These results suggest that all patients wearing any lower-limb plaster cast or knee brace are significantly impaired in their ability to perform an emergency stop. We suggest changes to the legislation to prevent patients from driving with lower-limb plaster casts or knee braces.

Steering and Handling Performance During a Full Tire Tread Belt Separation

In this study, tests were performed with modified tires at the various front and rear positions on seventeen different vehicles to determine the effect of a full tire tread belt separation on a vehicle at highway speeds. The driver's steering and braking inputs were measured along with the vehicle responses during the event. The results show that the forces of a full tread belt separation generally do not force a vehicle out of a driver's control and that only small steering corrections are required to remain in the original lane of travel during the tread belt separation event. Additionally, forces due to the separating tires do not result in violent hop or tramp suspension responses during the separation event. 2011 SAE International.

Nonvestibular Motion Cueing in a Fixed-Base Driving Simulator: Effects on Driver Braking and Cornering Performance

Motion platforms can be used to provide vestibular cues in a driving simulator, and have been shown to reduce driving speed and acceleration. However, motion platforms are expensive devices, and alternatives for providing motion cues need to be investigated. In independent experiments, the following eight low-cost nonvestibular motion cueing systems were tested by comparing driver performance to control groups driving with the cueing system disengaged: (1) seat belt tensioning system, (2) vibrating steering wheel, (3) motion seat, (4) screeching tire sound, (5) beeping sound, (6) road noise, (7) vibrating seat, and (8) pressure seat. The results showed that these systems are beneficial in reducing speed and acceleration and that they improve lane-keeping and/or stopping accuracy. The seat belt tensioning system had a particularly large influence on driver braking performance. This system reduced driving speed, increased stopping distance, reduced maximum deceleration, and increased stopping accuracy. It is concluded that low-cost nonvestibular motion cueing may be a welcome alternative for improving in-simulator performance so that it better matches real-world driving performance.

Analysis of Driver Brake Operation In Near-Crash Situation Using Naturalistic Driving Data

ABSTRACT: A large scale of field-test investigation was conducted in Beijing using Video Drive Recorder (VDR) which could record image in fron t of the v ehicle. Fifty taxis equipped with VD R were used to collect data in real traffic environments for a whole year and a larg e volume of natur alistic driving data including crashes and n ear-crashes was collected. This paper analyzed the pre-event maneuvers of drivers and studied the characteristics of braking operations of Conflict-prone drivers. Then an ev aluation method was proposed to rate a driver’s accidents avoidance ability, and to evaluate the relationships between driver's brake behaviors and accident rates. The results showed that most evasive maneuvers were within 2s before the most dangerous state. By comparing the near-crashes with crashes recorded by the VDR regarding traffic accidents in Beijing, great similarities were found in accident type and occurrence time between them. According to 100 rear-end near-crashes, if the braking time of drivers were delayed by 0.2s, 17% of near-crashes would have been crashes; and if the braking forces were decreased by 0.1g, 33% of near-crashes would have been crashes.

Improvement in vehicle agility and stability by G-Vectoring control

We extracted a trade-off strategy between longitudinal traction/braking force and cornering force by using jerk information through observing an expert driver's voluntary braking and turning action. Using the expert driver's strategy, we developed a new control concept, called ‘G-Vectoring control’, which is an automatic longitudinal acceleration control (No DYC) in accordance with the vehicle's lateral jerk caused by the driver's steering manoeuvres. With the control, the direction of synthetic acceleration (G) changes seamlessly (i.e. vectoring). The improvements in vehicle agility and stability were evaluated by theoretical analysis and through computer simulation. We then introduced a ‘G-Vectoring’ equipped test vehicle realised by brake-by-wire technology and executed a detailed examination on a test track. We have confirmed that the vehicle motion in view of both handling and ride quality has improved dramatically.

Driver Braking Performance to Surprise and Expected Events

Meta-analyses have shown that the driver braking characteristics reported in the literature often vary due to differences in study methodologies (Green, 2000; Muttart, 2005; Summala, 2000). This paper provides additional insight on driver braking performance by 1) characterizing driver behavior during the execution of surprise and expected braking maneuvers, and 2) investigating the effect of gender, age, and vehicle driven on this behavior. Sixty-four drivers performed surprise and expected braking maneuvers from 45 mph (72.4 km/h) at an inflatable barricade, and subsequently performed expected braking maneuvers in response to an auditory alarm. Participants drove one of two instrumented vehicles: 1) a 2006 Mercedes-Benz R350, or 2) a 2007 Volvo S80. Drivers' braking inputs and corrected stopping distance were measured. Results indicate that drivers' braking performance varied by gender, age, and vehicle driven. These results and their relationship to the extant braking literature are discussed. The findings are expected to benefit those involved in crash reconstruction, researchers modeling driver braking behavior, as well as designers of brake-by-wire systems.

608 自動車用自動操舵衝突回避システムに対するドライバブレーキの干渉(OS4-2 機械のダイナミクス2,オーガナイズドセッション:4)

608 自動車用自動操舵衝突回避システムに対するドライバブレーキの干渉(OS4-2 機械のダイナミクス2,オーガナイズドセッション:4)

Slip Suppression Control of Compact Electric Vehicle based on Brake Assist Using Haptic Pedal

Traffic accidents are big problems in our lives. Most causes of traffic accidents are because of human mistakes. The process of driving consists of three parts: recognition, judgment, and operation. Especially, 70% of the traffic accidents caused by human are recognition mistakes. Therefore, this paper proposes the haptic pedal system to transmit the road condition to the driver. This system assists the driver's braking operation to suppress the wheel slip. In order to convert the brake pedal into haptic pedal, sliding mode controller is applied. Simulation and experiment were conducted to show the validity of the proposed system.

5204 減速行動にもとづく追突警報タイミングの設定方策に関する考察(DS2 ドライバモニタリングと追突回避支援,ディベロップメント・セッション)

We investigated effects of missed alarms on driver's braking behaviour in response to alarm timing. By using a driving simulator, two kinds of alarm timing for forward collision warning systems were compared: (1) an alarm was given based on ordinary braking behaviour for the individual; alarm timing T, (2) an alarm was given by using an particular alarm trigger logic (Stopping Distance Algorithm); alarm timing S. It was found that compared to alarm timing S, alarm timing T had the potential to reduce negative effects of missed alarms on braking behaviour. Moreover, effects of missed alarm s on driver's trust may depend on alarm timing.