Strengthen preventability with sensor active safety system

In the future, the perfect car safety system must fully integrate gyroscopes, accelerometers, steering wheel and brake pedal position detectors, and tire speed detection systems to accurately monitor and warn car body parts.

Automobile safety systems have evolved from a passive form to an active form. Passive safety systems seek to reduce personal injury when accidents occur, but active safety systems emphasize the need to avoid accidents. This advance prevention capability depends on various sensing devices installed inside and outside the car, such as radar, infrared, CMOS / CCD image sensors, and tire pressure monitoring system (TPMS). Based on different safety demands, these monitored data will be calculated by a specific controller, analyze the meaning of the representative, and make the appropriate response at the fastest speed. The advanced security systems that have been used or are currently in development have shown an upsurge in application in the market.

Pre-collision system protects "inside and out"

Traffic accidents are mainly caused by collisions, and the reasons for collisions are often related to the driver's inattention (such as dozing or making phone calls), or poor sight, and the accidents usually occur only in a flash. Today's automobile factories are all committed to the development of pre-crash safety systems, which can be divided into two types: protection of internal drivers (or passengers) and protection of pedestrians.

For the driver, when the pre-crash safety system detects the possibility of impact through the radar system, it will warn the driver that if the collision cannot be avoided, the automatic braking system will be activated before 0.6 seconds. According to the driver's braking power, it can increase the brake oil pressure assist to make the vehicle's deceleration action more reliable, hoping to reduce the vehicle speed to the minimum; The seat belt is rolled back and the occupant is fixed in the optimal position designed, such as adjusting the position of the headrest to prevent neck injury, or moving the seat to a position where the airbag can maximize its function, in order to reduce the impact To the lowest. In addition, the system can also make control actions such as closing windows and sunroofs.

In terms of pedestrian protection, when components such as radar, infrared or image sensors sense that the vehicle body is about to collide with pedestrians, the pre-collision system will urgently inform the driver, and when a collision is inevitable, the automatic braking system will be activated as described above, Explode the airbags located at the bumper and front windshield to reduce injuries to pedestrians' heads, chests and feet.

Adaptive cruise system intervenes in vehicle control

From passive safety to pre-collision systems, it is a last resort to deal with crashes, but the best case is to prevent collisions in advance. By deploying more and more sensors around the car, and more advanced digital control technology, today â€™s car owners can obtain auxiliary driving information from the safety system, and when a possible crisis is detected, a warning signal can be issued in time, or even Able to intervene in the control of the car. Adaptive Cruise Control (AdapTIve Cruise Control, ACC) is such a system. Its main function is to decelerate the vehicle when the vehicle is too close, and accelerate the vehicle when the distance is far enough.

The adaptive cruise control system is an automatic speed control function for forward driving. It only partially interferes with the brakes, so that the driver is still in the position of master controller. The first task to achieve adaptive cruise control is to lock the target vehicle in front, and then calculate the movement information of the vehicle in front, such as speed, acceleration, yaw rate, etc .; the ACC system will base on the calculated distance and relative speed, as well as the owner The set reaction time further calculates the safe distance between the two vehicles and further accelerates and decelerates. When the distance between the two vehicles is too short, it switches to the pre-collision processing mode.

Multi-purpose CCD / CMOS for driving warning system

In addition to the control and processing of collisions and vehicle speeds, various behaviors of the driver can also be monitored and warned by various sensing systems. These warning functions include lane departure warning (Lane Departure Warning, LDW), driving hazard warning, visual blind spot warning (or blind spot detection) and so on. Most of these functions use CCD / CMOS image sensors for monitoring, and determine whether the vehicle or driving behavior is normal through a set of identification systems, and issue appropriate warning signals in due course.

Lane departure warning is a warning action when the vehicle departs from the lane line abnormally, assists the driver to control the vehicle to stay within the lane line, or reminds the driver to turn on the direction light first when changing lanes. If the driver turns on the direction lights before changing lanes, this is normal behavior and the system will not issue a warning signal.

The driving hazard warning system uses image sensors to monitor the driver's behavior. When the driver appears to be dozing off or the line of sight has deviated from the lane for too long, a warning will be issued. Some systems even monitor the alcohol concentration in the driver's seat and provide appropriate warnings. In addition, the driver's line of sight also has a lot of blind spots. By installing rear side blind spots and rear blind spot monitors, the driver can be provided with visual blind spot related environmental information. For example, the use of CCD or ultrasound to monitor, visualize and warn behind objects can avoid accidents when the vehicle is reversing.

For the driver, useful information can alleviate some of the perceived burden of manipulation and assist him to make appropriate response actions, but if the warning information appears too frequently and does not have much effect (such as "a speed camera before") Voice warning), which only makes the driver feel uncomfortable, and then refuses to use such a set of auxiliary systems. Another issue is how to issue a warning signal to let the driver know, such as voice, screen / dashboard display, or to warn the driver by vibrating the accelerator pedal, steering wheel or car body micro-motion.

Active safety systems have high requirements on sensors

To make correct warnings and even system monitoring, the key lies in sufficient and useful sensing information, and the ability to identify or judge the information. The former requires extensive sensor settings, and the latter depends on reliable algorithms in the controller. In terms of sensors, current technologies used for environmental perception include radar, light detection and ranging, infrared, ultrasound, image sensors and accelerometers. These technologies have their own characteristics, and are suitable for different positions and different applications in the car body.

In order to follow the preceding vehicle and pre-collision function, the sensor mainly uses millimeter wave radar or lidar. Among them, the cost of lidar is relatively low, only about 1/3 of the price of millimeter-wave radar. However, due to the relatively short wavelength of lidar, it cannot achieve the ideal function in rainy days. Therefore, in order to improve safety performance, high-end models will still choose Millimeter wave radar.

In the recognition of pedestrians, roads, obstacles and visual field assistance, infrared and image sensors are the main monitor technologies. Infrared monitors are further divided into far infrared (FIR) and near infrared (NIR) technologies. The principle of far infrared is to detect the heat of an object and then image the temperature difference, which is suitable for monitoring human bodies and animals with body temperature; near infrared has The ability of night vision can help display the road conditions ahead in an environment with poor sight (such as nighttime), and can display a position farther than the headlights. However, it will be affected by the front control lights.

The application of CCD or CMOS image sensors is also becoming wider and wider, and the application of auxiliary sight lines from the front, front side and rear has been expanded to the monitoring function of the interior and rear direction of the car. Through identification logic, it can be used to identify road dividers, pedestrians, traffic signal signs, or to determine whether the road surface is dry or water, snow, or even further speculate the wetness of the road surface for the driver's reference. For high-contrast or dark environments, the image sensor can also create a more distinct picture by combining two high-sensitivity and low-sensitivity images.

In addition, the image sensor can also be combined with infrared or radar to form a hybrid sensor, which can provide more powerful monitoring and warning functions. In the case of an infrared monitor, when the infrared rays reflected by the infrared LED illuminating the front are absorbed by the CCD, the road conditions around the vehicle can be recognized whether it is day or night.

A more intelligent active safety system must be realized by various sensors that are accurate and distributed throughout the body and inside of the car, and a computing platform with correct and immediate identification and judgment capabilities. Visual sensors (such as radar, infrared, image sensors, etc.) are just some of the many sensors. In the future, the perfect car safety system must fully integrate gyroscopes, accelerometers, steering wheel and brake pedal position detectors, and tire speed detection systems , To make accurate monitoring and warning of car body parts.

More and more sensors, more powerful calculation centers and control of brakes, engines, airbags and other devices will form a more complex in-vehicle network, which requires more real-time processing performance and data Transmission capacity. These intelligent auxiliary functions will make the driver drive more easily and at ease, and also help reduce the occurrence of traffic accidents or reduce the severity of the incident.