# Design and Testing of a Wearable System for Monitoring Car Drivers
## 1 Introduction  
The assessment of a driver's physiological state is of paramount importance for road safety and the development of advanced monitoring systems. The number of road accidents, even minor ones, is constantly increasing and represents a growing concern for road safety. Indeed, according to the latest data from the World Health Organization (WHO), approximately 1.35 million people die in road accidents each year, while up to 50 million people are injured or disabled. In this context, a thorough understanding of the factors influencing the mental and physical state of drivers is essential for designing effective solutions for detecting and preventing dangerous driving behaviors. Road accidents represent a major source of injuries, with neck trauma occupying a significant place. Even at low speeds, these incidents can have devastating consequences on the health and well-being of the individuals involved [1]. When a vehicle is rear-ended, the passengers' necks undergo a series of abrupt movements, putting strain on the delicate structures of this anatomical region [2]. These movements form what is called neck S-shape motion, consisting of three phases, retraction, forward movement, and belt restraint, as modeled in Figure 1. They can lead to injuries ranging from cervical strains to vertebral fractures, with potentially serious consequences for the mobility and quality of life of the victims. The monitoring of car driving behavior can help or even prevent car accidents producing serious injuries in car occupants. The modes of those injuries can also give indicationson the monitoring of the car driver motion that can be a function of their physiological and psychological status. The scientific literature has extensively documented the mechanisms of cervical injuries in road accidents. Research has shown that occupant position, seat design, and vehicle speed can all influence the severity of neck injuries [3]. Thus, by analyzing various cases of common accidents, one can identify several injury mechanisms such as hyperextension and hyperflexion of the neck, which occur during rear-end or frontal collisions and result in a sudden backward or forward projection of the head, respectively. Whiplash is a delicate and potentially deadly phenomenon that frequently occurs in this type of accident, although the current understanding of this injury risk remains limited [4]. Even when injuries are not as severe, some accidents can still pose considerable danger. In addition to rear-end and frontal collisions, side collisions can cause excessive rotation of the cervical spine, as often observed with the aspect that can lead to twists of the cervical vertebrae and injuries to surrounding tissues [5]. Considering these additional mechanisms, a deeper understanding of cervical injuries in road accidents can be gained with the aim to improve prevention measures and road safety. The risks to the neck are not limited to road accidents. Even minor incidents, such as sudden braking, can cause cervical injuries. When the head undergoes rapid forward and backward movement, it can create excessive strain on the soft tissues of the neck, leading to cervical strains and other similar injuries [6]. Although often considered minor effects, these injuries can have long-term consequences on the health and well-being of affected individuals. Similarly, road accidents can have a significant psychological impact on victims, especially when they suffer from persistent cervical injuries. Likewise, the economic costs associated with cervical injuries are also significant, with substantial annual expenditures on medical treatments and rehabilitation. In summary, road accidents pose significant health risks to the neck, even at relatively low speeds. Understanding the mechanisms of these injuries is essential for developing effective prevention and treatment strategies. To reduce these accidents and their consequences, innovative solutions have been proposed and studied.