Driver Braking Research Articles

Adapting Alarm Threshold to Driver's Brake Timing: Is it More Effective and/or Acceptable than Stopping Distance Algorithm?

In order to develop a useful forward collision warning system, it is important to determine the alarm timing appropriately. This study examined whether or not adapting alarm timing to driver's brake timing is more effective and/or acceptable by drivers than conventional Stopping Distance Algorithm (SDA). The results suggest that the proposed method can contribute to prevent rear-end collisions, and is as acceptable as SDA. Also, the driver adaptive alarm system may not suffer from driver's over-reliance.

The Influence of Lead Vehicle Behavior and Vehicle Rates of Closure on a Driver's Braking Behavior

Given the great prevalence of vehicle accidents, collision prevention should be a priority for ground transportation research. The understanding of such incidents is critical to the safety of the driver. This study involved simulations of multiple driving situations variant on Rate of Closure (the relative speed between two vehicles) and Lead Vehicle Behavior. Useful Field of View and Test Anxiety measures were used to analyze additional factors related to driving with little success. The findings show that brake onset times of younger drivers are significantly related to the behavior of a lead vehicle and to the rate of closure. As such, any system that only uses time to contact or distance to contact is fundamentally flawed. These results aid in the general understanding of driver behavior and could fundamentally change automatic braking systems.

Electric Braking Control Methods for Electric Vehicles With Independently Driven Front and Rear Wheels

For electric vehicles (EVs), the most important issue is safety when driving and braking operations are performed. EVs with a structure that can drive the front and rear wheels independently have been proposed by the authors, and they are being studied as the next ECO vehicles. The basic fail-safe function has already been verified through simulations and experiments to provide stable driving without any sudden stops even when the elements constituting the driving systems fail. Then, methods to control phenomena occurring at the time of braking, which are uncontrollable only by driver's pedal operations, i.e., wheel lock, slip, and aggravation of the riding comfort, are studied here based on a prototype EV with a function that can distribute the braking torque to the front and rear wheels according to driving conditions. As a result, electric braking control methods using the estimated vehicle speed, acceleration, and load movement are proposed that can prevent vehicles from experiencing wheel lock and slip phenomena and can improve the riding comfort regardless of a driver's braking pedal operations. Effectiveness of the proposed methods is verified through experiments using the prototype EV

3102 脇見運転時における前方衝突警報の欠報・誤報がドライバの運転行動に与える影響の研究(ドライバ行動-1,OS4 ヒューマンインターフェース)

When a driver in a following vehicle was looking aside while driving, the situation in which the preceding vehicle decelerated and told danger to the driver in the following vehicle by the forward collision warning was assumed. It was examined how driver's braking operation was influenced by the missing alarm or the false alarm. The results show that for missing alarms, the braking reaction time was delayed about 0.5 seconds compared to correct warnings.

An optimum braking strategy

Car-drivers often are required tobring their vehicle to a sudden stop when at a given speed to avoid colliding, for example, with a fixed obstacle (see Fig. 1). The first impulse is to exert and maintain maximum pressure on the brake until the car is halted, but this response is inadvisable since excessive decelerationmay cause skidding, and alsomay result in injury to the driver and passengers even when seat belts areworn. Just as importantly, a constant thrust on the brake pedal does not produce constant deceleration. Decades of experimental research on how shoe brakes effect the motion of wheels have conclusively demonstrated that the magnitude of the braking force decays rapidly with speed. It follows that, when the driver brakes at high initial speed, the braking force, small at the beginning, gradually increases to a given amount

τ as a potential control variable for visually guided braking.

D. N. Lee (1976) described a braking strategy based on optical expansion in which the driver brakes so that the target's time-to-contact declines around a constant slope in the range -0.5 < or = tau < 0. The present results from a series of braking simulations confirm and extend earlier reports (E. H. Yilmaz & W. H. Warren, 1995) that performance is broadly compatible with the tau hypothesis. However, performance was not enhanced in situations that favored the estimation of tau, and unlike in earlier reports, performance deteriorated in the absence of a ground plane that provided information about speed and target distance. This finding suggests that the tau hypothesis does not provide a complete account of braking control.

The influence of alarm timing on braking response and driver trust in low speed driving

Forward collision warning systems (FCWS) have been developed to reduce collision accidents caused by driver inattention. The timing of the alarm is a crucial factor in the determination of system effectiveness and in order to achieve the potential benefits it is necessary to estimate the effects of alarm timing on driver behaviour in all driving scenarios. In this study, we focused on driver behaviour when driving at relatively low speed (30 mile/h) and investigated the effect of alarm timing and driving demand on driver braking strategy in imminent collision situations. Three kinds of alarm timing condition (early alarms, late alarms, and no alarms) and two levels of driving demands (high and low decelerations of a leading vehicle) were considered and driver response to alarms was investigated from the viewpoint of driver trust. The results support the following conclusions. Trust in early alarms is higher than that in late alarms regardless of the differences in deceleration of the leading vehicle. In situations where the leading vehicle decreases its speed rapidly, an early alarm timing induces more timely and consistent braking actions than a late alarm timing. In situations where the leading vehicle decreases its speed gently an early alarm timing is unlikely to improve driver performance. Drivers who experience late alarms tend to respond to the brakes before an alarm sounds, moreover a late alarm timing has the potential to impair driver trust due to a conflict between driver expectation and alarm performance. Finally, evidence indicating a relationship between trust and alarm timing is discussed.

The effect of alarm timing on driver behaviour: an investigation of differences in driver trust and response to alarms according to alarm timing

The present paper describes a study concerned with the effect of alarm timing on driver trust and behaviour with a Forward Collision Warning System (FCWS). In this driving simulator experiment three different kinds of alarm timing (late/middle/early) were compared with respect to driver braking strategy and driver trust. The results showed that early alarm timing led to a more timely response to an imminent collision than either middle or late timing. With respect to driver trust, trust in late alarm timing is low compared with early or middle alarm timing. Furthermore the relationship between the timing of accelerator release and the timing of alarm onset is an important cause of changes in trust and if alarms are presented after drivers have already started to brake then trust is impaired. Middle alarm timing has the potential to improve driver braking response to imminent collisions. Possible benefits and drawbacks of FCWS are discussed from the viewpoint of alarm timing.

An Analysis of Driver's Behaviour during the System Limits (A Study Regarding the Warning Timing of System Limits for the Designing of Low Speed Adaptive Cruise Control Systems)

We analyzed the driver's braking behavior during the system-limit-warning, meaning the system is inevitable to avoid the collision on the preceding vehicle, when the driver was using Low Speed Adaptive Cruise Control. It was observed that the drivers are judging the condition of system-limits, not only by themselves but also by the system-limit-warning. Driver's braking behavior was delayed when the assumed delay time was set at less than 1.2 s in the Stopping Distance Algorithm. We also analyzed the driver's braking behavior in the miss warning condition. Driver's braking behavior during the miss warning was extremely delayed when the assumed delay time was set at less than 1.0 s. In the designing of warning timing by use of Stopping Distance Algorithm, one of the optimal warning timing is 1.2s, when we focus on not only the normal condition that the warning system operate accurately but also the miss warning condition.

A Car-Following Model Based on a Self-Learning Neuro-Fuzzy Controller

This paper focuses on a car-following model that can be used in traffic simulation. A new approach is proposed for emulating the driver's decision-making process. The approach uses fuzzy reasoning for dealing with uncertainty and blending behaviors induced by simultaneous goals. An original algorithm is implemented in the system for imitating the driver's self-learning from actual driving experience and for mimicking the driver's braking and accelerating maneuvers.

Comparison of Driver Braking Responses in a High-Fidelity Simulator and on a Test Track

The braking responses of drivers in the Iowa Driving Simulator (IDS) were compared with those of drivers on a test track. The braking profile of drivers was compared in last-minute braking situations in which drivers were instructed to brake “normally” or “hard.” Although the motion and visual cues in the IDS are imperfect, the data agree in many respects. The general pattern of results is similar, with the initial speed and lead vehicle deceleration affecting drivers on the test track and in the simulator in a similar way. In several experimental conditions, the similarity of the responses went beyond the general pattern of response. The mean values were almost identical in several instances, and the values were frequently well within the confidence intervals. Although the simulator and test track drivers performed similarly, differences are apparent from the onset of braking, through the braking process, and in the outcome of the braking event. The instructions concerning normal and hard braking had little influence on the behavior of drivers in the simulator. Contributors to these differences include the limited visual and vestibular cues in the simulator and the extended practice on the test track.

Driver Braking Performance in Stopping Sight Distance Situations

Assumed driver braking performance in emergency situations is not consistent in the published literature. A 1955 study stated that in an emergency situation “it is suspected that drivers apply their brakes as hard as possible.” This idea differs from a 1984 report that states drivers will “modulate”their braking to maintain directional control. Thus, additional information is needed about driver braking performance when an unexpected object is in the roadway. In this research driver braking distances and decelerations to both unexpected and anticipated stops were measured. The study design allowed for differences in vehicle handling and driver capabilities associated with antilock braking systems (ABS), wet and dry pavement conditions, and the effects of roadway geometry. Vehicle speeds, braking distances, and deceleration profiles were determined for each braking maneuver. The research results show that ABS result in shorter braking distances by as much as 30 m at 90 km/h. These differences were most noticeable on wet pavements where ABS resulted in better control and shorter braking distances. Braking distances on horizontal curves were slightly longer than on tangent sections; however, they were not large enough to be of practical significance. Maximum deceleration during braking is independent of initial velocity, at least in the range of speeds tested. Differences were noted in individual driver performance in terms of maximum deceleration. Although maximum deceleration was equal to the pavement’s coefficient of friction for some drivers, the average maximum deceleration was about 75 percent of that level. Overall, drivers generated maximum decelerations from 6.9 to 9.1 m/s2. The equivalent constant deceleration also varied among drivers. Based on the 90-km/h data, 90 percent of all drivers without ABS chose equivalent constant decelerations of at least 3.4 m/s2 under wet conditions, and 90 percent of all drivers with ABS chose equivalent constant deceleration of at least 4.7 m/s2 on dry pavements.

Closed-loop analysis of vehicle behavior during braking in a turn

This paper discusses an analysis of “driver-vehicle” behavior during braking in a turn. In this study, a new braking model was developed in consideration of actual driver's operation, and experiments were conducted on mountain roads to identify one novice and one skilled driver's braking model parameters. The computer simulations have shown the following tendency. The novice driver needed more compensatory steering operation than the skilled driver to trace the course. A controlled braking force distribution was particularly effective for the novice driver.

Preferred time headway in car-following and individual differences in perceptual-motor skills.

18 subjects were tested in a simulator to assess whether choice of time headway in car-following is related to individual differences in perceptual-motor skills. Drivers with a larger preferred time headway committed larger steering errors while driving on a winding road and were less accurate in maintaining a constant distance to a lead vehicle that varied its speed between 80 and 100 km/hr. compared to drivers with a smaller preferred time headway. Also, time to collision with the lead vehicle hardly affected the braking response of drivers with a larger preferred time headway. In contrast, the braking response of drivers with a smaller preferred time headway was strongly affected by time to collision with the lead vehicle. The results support the hypothesis that preferred time headway is at least to some extent the result of adaptation to the driver's braking performance and perceptual-motor skills.

9733026 Development of assistant system to average driver's braking operation in a panic situation Atsushi Yamamoto, Jiro Kizaki, Hiroaki Yoshida, Yoshiyuki Hashimoto (Toyota Motor Corporation)

9733026 Development of assistant system to average driver's braking operation in a panic situation Atsushi Yamamoto, Jiro Kizaki, Hiroaki Yoshida, Yoshiyuki Hashimoto (Toyota Motor Corporation)

Driver Perception–Brake Response in Stopping Sight Distance Situations

One of the most important requirements in highway design is the provision of adequate stopping sight distance at every point along the roadway. At a minimum, this sight distance should be long enough to enable a vehicle traveling at or near the design speed to stop before reaching a stationary object in its path. Stopping sight distance is the sum of two components–brake reaction distance and braking distance. Brake reaction distance is based on the vehicle’s speed and the driver’s perception–brake reaction time (PBRT). Four separate, but coordinated, driver braking performance studies measured driver perception–brake response to several different stopping sight distance situations. The results from the driver braking performance studies suggest that the mean perception–brake response time to an unexpected object scenario under controlled and open road conditions is about 1.1 s. The 95th percentile perception–brake response times for these same conditions was 2.0 s. The findings from these studies are consistent with those in the literature: that is, most drivers are capable of responding to an unexpected hazard in the roadway in 2.0 s or less. Thus, the American Association of State Highway and Transportation Officials’ perception–brake response time of 2.5 s encompasses most of the driving population and is an appropriate value for highway design.

SHORT NOTE: Field Evaluation of an Advance Brake Warning System

A field study was conducted to evaluate an advance brake warning (ABW) light activation system. The ABW system detects very rapid accelerator pedal releases (assumed to characterize contingent braking responses) and activates the brake light. If the driver brakes within 1.0 s, then continuation of the brake light is governed by the brake pedal. Otherwise the light goes off. The ABW system was installed on six vehicles driven by their regular users, who were unaware of the system or the study. A total of 61 668 km were driven, in which the drivers braked 95394 times. The ABW system was activated on 820 of those occasions, providing the following driver a 0.22 s warning. It was determined that the emergency braking activating the ABW system is relatively rare, occurring on average 13.3 times per 1000 km and less than 1% of all brake actions. False alarms (ABW activation without braking) occurred in 23% of all ABW activations but were insignificant (1 in 50) relative to the total number of brief braking actions lasting less than 1.0 s. It therefore appears that the advance brake warning light can provide the intended information without being a safety hazard to following drivers.

A field study on braking responses during driving. II. Minimum driver braking times

The minimum total braking time (i.e. the braking reaction time plus the accelerator-to-brake movement time) plays an important role in defining a minimum following gap (MFG). This study was designed to obtain a lower limit for this gap. Total braking times (TBT) of a group of 51 male and female young athletes were monitored during real driving conditions. Sudden braking applied by a leading private passenger vehicle initiated the trials. A within-subject design was used to study the effects of different factors on braking time. Individuals performed a series of semi-counterbalanced trials at two following distances (6 and 12 m), two speeds (60 and 80 km/h) and three expectancy stages (naive driving, partial knowledge, and full knowledge of the forthcoming manoeuvre). A three-way repeated measures ANOVA showed no major effects of ‘speed’, but major effects of the ‘expectancy’ and the ‘distance’ factors. The experiment yielded a mean TBT of 0·678 s (SD = 0·144 s) for trials averaged over distances and speed...

The Potential Value of a Front-to-Rear-End Collision Warning System Based on Factors of Driver Behavior, Visual Perception and Brake Reaction Time

The potential value of a front-to-rear-end collision warning system based on factors of driver behavior, visual perception and brake reaction time is examined in this paper. Twenty-four percent of all motor vehicle crashes involving two or more vehicles are front-to-rear-end collisions. These collisions demonstrate that several driver performance factors are common. The literature indicates that drivers use the relative size and the visual angle of the vehicle ahead when making judgments regarding depth. In addition, drivers often have difficulty gauging velocity differences and depth cues between themselves and the vehicle they are following. Finally, drivers often follow at distances that are closer than brake-reaction time permits for accident avoidance. It is apparent that the comfort level of close following behavior increases over time due to the rarity of consequences. Experience also teaches drivers that the vehicle in front does not suddenly slow down very often. On the basis of these driver behavior and human performance issues, a front-to-rear-end collision warning system that provides headway/following distance and velocity change information is considered. Based on the driver performance issues, display design recommendations are outlined. The value of such a device may be demonstrated by the added driver safety and situation awareness provided. The long-term goal would ultimately be the reduction of one of the most frequent type of automobile crashes.

Modeling Driver/Vehicle Performance in Emergency Maneuvers

The combined performance of the driver and vehicle determine whether accidents result from traffic conflicts, road hazards, etc. This paper describes the driver behavior and hazard scenario aspects of a computer simulation which models both vehicle dynamics and driver steering and braking behavior. The technical aspects of the simulation have previously been published. The issue of how much the driver and vehicle contribute to accident involvement is addressed, and antilock brake evaluation is used as an example.