Abstract. A driver's response to a front-coming vehicle collision consists of braking reaction time and braking behavior. The purpose was to investigate drivers' responses at different speeds, relative distances, and particularly the behavior on the accelerator at the collision moment. Twelve young men participated in driving simulator tests. Vehicle parameters and electromyograms (EMGs) of the drivers' tibialis anterior muscles were recorded and responses were analyzed. The drivers' braking reaction time windows were divided into pre-motor time, muscle activation time, accelerator release time, and movement time. By comparing the reaction times and collision times, braking behaviors were investigated. It was found that movement times (r = -0.281) decreased with speed. Pre-motor times (r = 0.326) and muscle activation times (r = 0.281) increased with relative distance. At the collision moment, the probability of the driver's lower extremity being on the accelerator, in the air, and on the brake pedal was 7.4%, 18.9%, and 73.7%, respectively. With higher speeds and smaller distances, the lower extremity was more likely to be in the air or even on the accelerator in different muscle activation states. The driver will collide in normal driving postures which muscles are not or not fully activated in very urgent situation.

Abstract. Frontal vehicle collisions can cause injury to a driver's cervical muscles resulting from intense changes in muscle strain and muscle load. This study investigated the influence of collision forces in a sled test environment using a modified Hybrid III 50 th percentile dummy equipped with simulated spring-type muscles. Cervical muscle responses including strain and load of the sternocleidomastoid (SCM), splenius capitis (SPL), and trapezius (TRP) were analyzed, and muscle injury was assessed. The SCM, SPL, and TRP suffered average peak muscle strains of 21%, 40%, and 23%, respectively, exceeding the injury threshold. The average peak muscle loads of the SCM, SPL and TRP were 11 N, 25 N, and 25 N, respectively, lower than the ultimate failure load. The SPL endured the largest injury, while the injuries to the SCM and TRP were relatively small. This is a preliminary study to assess the cervical muscle of driver during a frontal vehicle collision. This study provides a foundation for investigating the muscle response and injury in sled test environments, which can lead to the improvement of occupant protections.

Ankle dorsiflexion is firstly activated at the beginning of the emergency brake motion. Males showed stronger reaction ability than females, as suggested by male's shorter PMT. The detection of driver's brake intention is upwards of 55ms sooner after introducing the electromyography. Muscle activation of the lower extremity is an important factor for 50 km/h collision injury analysis. For higher speed collisions, this might not be a major factor. The activations of certain muscles may be ignored for crash injury analysis at certain speeds, such as gluteus maximus at 25 or 100 km/h. Furthermore, the activation of certain muscles should be differentiated between males and females during injury analysis.

No abstract

The influence of cervical muscles on the head/neck responses to frontal collisions is an important issue in the design of vehicle safety systems. In this study, spring-type muscles based on a Hybrid III 50th percentile dummy were used. A spring was used to simulate the cervical muscle with the instinctual physiological reaction of a driver. A total of 10 volunteers were recruited for the simulated collision tests and the maximum voluntary contraction tests, and test data were used to establish and design the spring-type muscles. Sled tests were performed using a modified dummy with spring-type muscles, which had similar mechanical characteristics to a human body. The results showed that Ax increased 3.58%, Ay decreased [Formula: see text]10.32%, Az increased 3.21%, Fx increased 12.22%, Fz increased 3.80%, and My decreased significantly ([Formula: see text]16.70% in average) at first but then increased 5.57%, in average. Cervical muscles with the instinctual physiological reaction may increase the potential head injury and potential cervical longitudinal shear injury while decreasing the potential cervical extension injury. The study provides reference for designing dummies by taking into consideration the instinctual physiological reaction of the driver to a collision.