From the power windows in the early 1950s to the latest car driving systems today, the high-end features of luxury cars will eventually be applied to mid-range and economy cars over time, becoming a necessary electronic and electrical system . The newly emerging advanced assisted driving system (ADAS) technology is no exception. As an example, European Ford Focus cars now have features such as adaptive cruise control (ACC), automatic braking, and active lane keeping—all of these features were previously exclusive to luxury cars. Even the economical Kia cars have rear-view cameras installed. However, as ADAS technology is applied to relatively cheap vehicles, this poses a dilemma: it needs to implement a large amount of computing resources at a very low price.
ADAS technology can be applied not only to luxury cars, partly because of competition considerations, but not the only factor. Government regulations are also an important factor. For example, in the United States, the National High Speed ​​Transportation Security Administration is formulating a policy to force the installation of rear-view cameras [source: http: //]. According to this, it is expected that in 2018, 60 million vehicle-mounted cameras will be installed. EC will enforce the advanced emergency braking system and lane departure warning (LDW) system in 2015. [Source: [http: //? id = 84]
ADAS installed vehicles with discounts on insurance are another factor driving the widespread use of ADAS. Such discounts have certain statistical significance. When the driver starts to deviate from the lane, the system will issue a warning. At night, the system can also enhance the visibility of the driver, thereby avoiding accidents and saving lives.
The decisive factor for the widespread use of ADAS is still cost. Although ADAS technology is becoming more and more complex, the advancement of sensor and processor technology-integrating multiple functions in few components, can now support engineers to design ADAS at a price that mid-range or even economical cars can afford application. The reduction of cost and the reduction of complexity through function integration are the key factors that promote the wide application of ADAS technology in various vehicles.
Functional diversity
In all its expectations, ADAS technology has also brought many challenges to the automotive industry. Just as many technologies are in their early stages, ADAS applications have involved many development directions, and it is not clear which direction will ultimately promote market development. At the time of writing, Hitachi focused on using two forward camera multi-sensor methods to detect objects at a distance of 100 meters. This technology is called "eye vision" and is used in 2013 Legacy and Outback models. Denso recently demonstrated a drowsiness detection system that uses infrared (IR) cameras to observe the driver's face and determine whether the driver's eyes are open. If the eyes are closed, the driver may have fallen asleep. Finally, Aisin is introducing a lane detection system using a rear-view camera-this is a cost-effective method of monitoring the position of the vehicle relative to the lane marking. It combines GPS and road map data to determine the current position of the vehicle relative to the road conditions ahead.
This article will introduce in more detail the ADAS technology quickly applied in a wider market.
System: Lane departure warning
Sensor: camera
When the vehicle leaves its lane or approaches the edge of the road, the LDW system issues an audible alarm or motion alarm (through a slight vibration of the steering wheel or seat). When the vehicle speed exceeds a certain threshold (for example, greater than 55 miles) and the vehicle does not turn on the turn signal lights, these systems will come into play. When the vehicle is driving and its position relative to the lane marking line indicates that the vehicle may deviate from the lane, the lane marking needs to be observed through the camera system. Although these application requirements are similar for all vehicle manufacturers, each manufacturer adopts a different approach, using a front-view camera, a rear-view camera, or a dual / stereo front-view camera. For this reason, it is difficult to adopt a hardware architecture to meet the requirements of various types of cameras. Need to adopt flexible hardware architecture to provide different implementation options.
System: Adaptive cruise control
Sensor: Radar
Over the past decade, luxury cars have adopted ACC technology, which is also currently being used in a wider market. Traditional cruise control technology is designed to keep the vehicle driving at a constant speed. Unlike this, ACC technology adapts the vehicle speed to traffic conditions. If it is too close to the vehicle in front, it will slow down and accelerate when the road conditions allow To the upper limit. These systems are implemented by using radar installed in the front of the vehicle. However, because the radar system cannot recognize the size and shape of a certain target, and its field of view is relatively narrow, it should be combined with a camera when applied. The difficulty is that the cameras and radar sensors currently used do not have a standard configuration. Therefore, a flexible hardware platform is still required.
System: traffic sign recognition
Sensor: camera
As its name suggests, the traffic sign recognition (TSR) function uses a forward-facing camera combined with pattern recognition software to identify common traffic signs (speed limit, parking, U-turn, etc.). This function will remind the driver to pay attention to the traffic signs in front, so that the driver can observe these signs. The TSR function reduces the possibility of drivers not complying with traffic signs such as stop signs, and avoids illegal left-turning or other unintentional traffic violations, thereby improving safety. These systems require flexible software platforms to enhance the detection algorithm and adjust according to traffic signs in different regions.
System: Night Vision
Sensor: IR or thermal imaging camera
The night vision (NV) system helps drivers recognize objects in very dark conditions. These objects generally exceed the field of view of the vehicle's headlights. Therefore, the NV system issues an alarm in advance for vehicles driving on the road ahead to help the driver avoid collisions.
The NV system uses various camera sensors and displays, which are specific to the manufacturer, but generally fall into two basic types: active and passive.
An active system, also known as a near-IR system, combines a charged coupled device (CCD) camera and an IR light source to present a black and white image on the display. The resolution of these systems is very high, and the image quality is also very good. Its typical visual range is 150 meters. These systems can see all objects within the camera's field of view (including objects without heat radiation), but in rain and snow, the efficiency is greatly reduced.
Passive systems do not use external light sources, but rely on thermal imaging cameras to capture images using natural thermal radiation from objects. These systems will not be affected by the headlights of the oncoming vehicles, nor will they be affected by severe weather conditions, and their detection range will reach 300 meters to 1000 meters. The disadvantage of these systems is that the images are grainy and their functions are limited to warmer climates. Moreover, passive systems can only detect objects with thermal radiation. Passive system combined with video analysis technology can clearly display objects on the road in front of the vehicle, such as pedestrians.
In an NV system, there are multiple architectural choices, and each method has its advantages and disadvantages. To increase competitiveness, auto manufacturers should support multiple camera sensors and implement these sensors on a common and flexible hardware platform.
System: Adaptive high beam control
Sensor: camera
Adaptive high beam control (AHBC) is an intelligent headlight control system that uses cameras to detect traffic conditions (opposite cars and traffic in the same direction), and brightens or dims the high beam lights based on these conditions. The AHBC system supports the driver to use the high beam at the maximum lighting distance as much as possible, without having to dim the headlights manually when other vehicles appear, without distracting the driver ’s attention, thereby improving the safety of the vehicle. In some systems, you can even control the headlights separately, dim one headlight, and at the same time the other headlight is normally lit. AHBC and LDW and TSR and other forward-looking camera systems are complementary. These systems do not require high-resolution cameras. If a vehicle already uses a forward-looking camera in ADAS applications, the cost-effectiveness of this feature will be very high.
System: Pedestrian / obstacle / vehicle detection (PD)
Sensors: camera, radar, IR
Pedestrian (and obstacle and vehicle) detection (PD) systems rely entirely on camera sensors to perceive the surrounding environment in depth, for example, using a single camera, or using a stereo camera in a more complex system. The "category variables" (clothing, lighting, size, and distance) will vary greatly, and the background is complex and constantly changing, and sensors are placed on mobile platforms (vehicles) and other factors, making it difficult to determine the visual characteristics of pedestrians on the move, so , The use of IR sensors can enhance the PD system. Radar can also enhance the vehicle detection system. It provides a very good distance measurement function. It can perform well under severe weather conditions and can measure the speed of a vehicle. This complex system requires the use of data from multiple sensors simultaneously. (This process called sensor fusion will be discussed in detail later.)
System: Driver sleepiness alarm
Sensor: IR camera in the car
The drowsiness alarm system monitors the driver's face, measuring his head position, eyes (open / closed) and other similar alarm indications. If it is determined that the driver has signs of going to sleep, or looks unconscious, the system will issue an alarm. Some systems also monitor heart rate and breathing. The functions envisaged but not yet implemented include driving the vehicle close to the roadside and eventually stopping by the side.
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