1. Purpose and significance

1.1 Research purpose

With the development of social productivity, intelligent technology has been widely used around us. Automobile, as an intelligent synthesis, has made great contributions to the development of society and the change of human travel conditions during the 100 years since its birth. ^[1] in recent years, human beings have been making great contributions to pattern recognition, image processing, and so on. The application of neural network and expert control technology in automobile has made the whole mechanism of automobile not as complex as before. At the same time, many scientific research achievements have been made by human beings. For example, the automobile with automatic injection control engine system can effectively improve the efficiency of gasoline engine and save a lot of energy. The application of anti-lock braking in braking system improves the safety and stability of vehicle travel and prevent the vehicle from turning over and swinging sharply due to the emergency brake.The improvement of suspension system makes the vehicle travel more smoothly and provides drivers and passengers with a more comfortable driving environment and riding environment. ^[2] With the improvement of human living standards, the number of cars is also increasing, resulting in such as traffic congestion, traffic accidents, energy waste and environmental pollution. Especially in recent years, traffic accidents remain high, the death rate caused by traffic accidents is also rising year by year. The result is an incalculable economic loss. At this time, people hope that the car can automatically identify the road, can automatically control the safe driving of the vehicle according to the planned path, and other advanced functions. So the driver can be solved from the boring and cumbersome driving behavior and that will make driving safer. This also highlights the necessity and urgency of developing an intelligent control system for vehicles.

The self-driving intelligent vehicle has experienced the development of several stages, such as concept research, model test, sample car development, design and stereotyping, small batch production, supply and so on. It can be divided into two categories: one is the remote control vehicle, the other is the autonomous vehicle. Remote control vehicles mainly rely on wired and wireless network mode operators long-distance control to achieve self-driving. Autonomous vehicles can also be called intelligent vehicles or mobile robots. They usually use visual sensors installed on the body of the car, laser rangefinder to sense the environment around the vehicle, gyroscope, and integrated inertial navigation system for positioning and orientation. ^[3] Vehicle positions are obtained from these sensors. The obstacle information is transmitted to the vehicle body control layer to control the steering and speed of the vehicle, so that the vehicle can travel safely and reliably on the road.

1.2 Research significance

(1) Making self-driving behavior of unmanned vehicle measurable and controllable. The driver's driving behavior to the vehicle should be driven by himself. Driving skills mean the ability to understand vehicle performance and road information, personal driving habits, and psychological status in handling emergencies. Many other aspects of the influence vary from person to person in very strong randomness. However, when designing the self-driving system of unmanned vehicles, due to the perception of the outside world, the analysis of the system is calculated by the computer, and the personal factors of the driver are discharged, thereby making driving behavior predictable. And there is no doubt in the benefits of this in terms of the safety of vehicles.

(2) The rapid response of vehicle system to an environment is improved. Through a large number of experimental studies and analysis of the data, it is shown that the response time of a human driver to an external emergency is much longer than that of a computer. For example, when a driver operates a brake, the response time of the system is generally in-second, and is even longer for vehicle steering. After computer calculation processing, the braking reaction time can be controlled in seconds or even smaller. This not only adds to the transport capacity of the intelligent transportation system, but also enhance the safety and stability of the vehicle.

(3) Improve the precision of vehicle's perception to the environment. Human perception of the environment can’t be as accurate as an electronic sensor. The use of electronic sensors makes the unmanned vehicle more accurate in the perception of the complex environment outside the world and improves vehicle handling accuracy and certainty.

1.3 General situation of domestic Research

Under the restriction of national economic conditions, the research on self-driving intelligent vehicles in China is a little relative late to the developed foreign countries. But through the efforts of the Chinese people, so far, our country has been in the development of unmanned vehicles. Encouraging results have been achieved, such as:

1. Tsinghua University in China has made in 2003 a breakthrough in the research on the unmanned vehicle control system. The design of the TH-MRV car in the white line tracking experiment has reached 150 km per hour. ^[9]

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