Showing papers on "Rear-end collision published in 1997"

Do "whiplash injuries" occur in low-speed rear impacts?

Abstract: A study was conducted to find out whether in a rear-impact motor vehicle accident, velocity changes in the impact vehicle of between 10 and 15 km/h can cause so-called “whiplash injuries”. An assessment of the actual injury mechanism of such whiplash injuries and comparison of vehicle rear-end collisions with amusement park bumper car collisions was also carried out. The study was based on experimental biochemical, kinematic, and clinical analysis with volunteers. In Europe between DM 10 and 20 billion each year is paid out by insurance companies alone for whiplash injuries, although various studies show that the biodynamic stresses arising in the case of slight to moderate vehicle damage may not be high enough to cause such injuries. Most of these experimental studies with cadavers, dummies, and some with volunteers were performed with velocity changes below 10 km/h. About 65% of the insurance claims, however, take place in cases with velocity changes of up to 15 km/h. Fourteen male volunteers (aged 28–47 years; average 33.2 years) and five female volunteers (aged 26–37 years; average 32.8 years) participated in 17 vehicle rear-end collisions and 3 bumper car collisions. All cars were fitted with normal European bumper systems. Before, 1 day after and 4–5 weeks after each vehicle crash test and in two of the three bumper car crash tests a clinical examination, a computerized motion analysis, and an MRI examination with Gd-DTPA of the cervical spine of the test persons were performed. During each crash test, in which the test persons were completely screened-off visually and acoustically, the muscle tension of various neck muscles was recorded by surface eletromyography (EMG). The kinematic responses of the test persons and the forces occurring were measured by accelerometers. The kinematic analyses were performed with movement markers and a screening frequency of 700 Hz. To record the acceleration effects of the target vehicle and the bullet vehicle, vehicle accident data recorders were installed in both. The contact phase of the vehicle structures and the kinematics of the test persons were also recorded using high-speed cameras. The results showed that the range of velocity change (vehicle collisions) was 8.7–14.2 km/h (average 11.4 km/h) and the range of mean acceleration of the target vehicle was 2.1–3.6 g (average 2.7 g). The range of velocity change (bumper car collisions) was 8.3–10.6 km/h (average 9.9 km/h) and the range of mean acceleration of the target bumper car was 1.8–2.6 g (average 2.2 g). No injury signs were found at the physical examinations, computerized motion analyses, or at the MRI examinations. Only one of the male volunteers suffered a reduction of rotation of the cervical spine to the left of 10° for 10 weeks. The kinematic analysis very clearly showed that the whiplash mechanism consists of translation/extension (high energy) of the cervical spine with consecutive flexion (low energy) of the cervical spine: hyperextension of the cervical spine during the vehicle crashes was not observed. All the tests showed that the EMG signal of the neck muscles starts before the head movement takes place. The stresses recorded in the vehicle collisions were in the same range as those recorded in the bumper car crashes. From the extent of the damage to the vehicles after a collision it is possible to determine the level of the velocity change. The study concluded that, the “limit of harmlessness” for stresses arising from rear-end impacts with regard to the velocity changes lies between 10 and 15 km/h. For everyday practice, photographs of the damage to cars involved in a rear-end impact are essential to determine this velocity change. The stress occurring in vehicle rear-end collisions can be compared to the stress in bumper car collisions.

Rear-end collision alarming device and method linked to speed control device of a vehicle

Abstract: An rear-end collision alarming device issuing an alarm for preventing a rear-end collision against a vehicle running ahead determines whether a gas pedal is operated when it is determined that a subject vehicle approaches the vehicle running ahead. If the gas pedal is not operated, this means that a driver does not react to the approach. Therefore, the device notify the driver of the approach to the vehicle running ahead through an alarm sound or light.

Vehicle seat with headrest adjustable on the backrest

Abstract: A vehicle seat for a vehicle occupant has a backrest, a headrest arranged adjustable on the backrest and being movable from a normal starting position into a restraint position approximating the head of the vehicle occupant, a vehicle-sensitive activatable positioner and a flexible traction transmitting means connecting the headrest and the positioner. The positioner moves the headrest in the case of a rear end collision of the vehicle from the normal starting position into the restraint position by transmitting force via the traction transmitting means. The traction transmitting means extends through the backrest.

Collision avoidance behavior of unalerted drivers using a front-to-rear-end collision warning display on the Iowa driving simulator

Abstract: This study investigated whether drivers who operate a vehicle equipped with a front-to-rear-end collision warning system can avoid crashing when a lead vehicle brakes at its maximum potential (e.g., -0.85 g). Drivers in the experimental condition drove a 1993 General Motors Saturn mounted on the Iowa Driving Simulator's six-degree-of-freedom motion base. The simulator cab was equipped with a collision warning display that provided a primary auditory warning and secondary visual warning based on a time-to-collision algorithm between the subject's vehicle and the lead vehicle. Two headway distances were tested (2.7 sec and 3.2 sec). The collision avoidance performance of subject drivers was compared to the behavior of drivers in a baseline condition where no collision warning display was present. Relative to the baseline condition, results indicate that drivers using the collision warning display (a) showed significantly fewer crashes in the shorter headway condition, (b) collided with the lead vehicle at s...

Time-to-collision judgements: visual and spatio-temporal factors

Abstract: A fundamental aspect in driving is predicting critical events in the near future. A driver on a collision course, for example, has to accurately evaluate how close s/he is to the impending collision in order to brake or swerve at the right time. In other words, s/he has to judge time-to-collision (TTC), which refers to the time that remains before reaching an obstacle, and thus to the time available for taking action. TTC is considered to be a crucial parameter in controlling avoidance behaviour. TTC is also likely to be involved in more complex judgement tasks such as overtaking or left-turn manoeuvres, where the driver has to determine whether there is enough time for the planned action. The underlying concept of temporal action control is being used increasingly often in the study of driving behaviour, which addresses the anticipatory aspects of actions such as braking, trajectory control, car following, traffic merging decisions, curve taking, stop-or-go decisions at intersections, and so on. Various equivalent terms have been employed, depending on the situation under investigation, including 'time-to-contact', 'time-to-arrival', and 'time-to-go'. The concept has also proven useful in aircraft conflict resolution and ship piloting, which involve considerably larger time frames. The current study is more specifically concerned with impending collision situations which occur when a driver is approaching a stationary vehicle. The objective was to investigate the determinants of perception-related errors which are thought to contribute to rear-end collisions (Mortimer, 1990). Rear-end collisions represent 20-25% of the total number of accidents, and 80% of rear-end crashes occur in situations where the vehicle struck was stationary or travelling very slowly. A better understanding of the visual information that drivers need to accurately judge TTC in this situation is an important condition for effective preventive action. For the covering abstract, see IRRD 896859.

Development of rear-end collision avoidance system

Abstract: RCAS (rear-end collision avoidance system) has been developed as a system of ASV (advanced safety vehicle). It is a driver assist system to avoid the rear-end collision by informing the distance headway. It also has automatic braking function in case of emergency and distance warning function to the trailing vehicle. This paper describes the outline of RCAS, techniques about the preceding vehicle recognition and collision potential hazard evaluation. And experimental results about distance headway warning and collision avoidance by automatic braking are reported.

Development of collision warning system and its collision avoidance effect

Abstract: This paper describes experimental results and effectiveness of a Collision Warning System (CWS) as demonstrated on a driving simulator. The two key technological elements of the system are: (1) a path estimation algorithm, which is a method to determine the location of a preceding vehicle; and (2) a danger judgement algorithm which can predict collisions with preceding vehicles. The characteristic of the path estimation algorithm is that it uses variances of distances and azimuths to forward obstacles. This algorithm can also simultaneously estimate vehicle sideslip angle. The characteristic of the danger judgement algorithm is that it changes the critical headway distance when it detects the deceleration of a preceding vehicle. This algorithm can make quick and smart warnings. The evaluation of this system by the driving simulator shows the possibility that this algorithm can avoid collisions twice what the conventional one can. For the covering abstract, see IRRD 490001.

Device for preventing rear-end collision for automobile

Abstract: PROBLEM TO BE SOLVED: To provide a rear-end collision preventing device whereby the reference in-vehicle distance for starting a rear-end collision evading countermeasure can be made a proper value corresponding to the operation characteristic of a driver. SOLUTION: The device is constituted to take the rear-end collision evading countermeasure when the distance between a vehicle on which the device is mounted, and a preceding vehicle becomes equal to a prescribed value or smaller. In this case, the device is provided with CPU 10 which functions as a reference in-vehicle distance correcting means for adjusting reference in-vehicle distance for starting the rear-end collision evading countermeasure by a correction value corresponding to the operation characteristic of the driver and also as an adjustment restricting means for restricting adjustment width by the correction value to be smaller value when a probability to cause an operation mistake is higher.