Withthe development of social economy and the increasing number of automobile ,traveling becomes convenient and fast, but traffic congestion and trafficaccidents have been a major problem in today's society. In order to solve theseproblems, with the use of computer control technology and automatic controltechnology in automobiles, we get a driverless car, which means a majorrevolution in the automotive industry. Driverless cars, also known asself-driving cars or wheeled mobile robots, which could perceive thesurroundings with on-board sensors without driver, and Implement the drivingprocess relying on intelligent pilot according to the obtained information. ^[1]

Atthis stage, most of the countries are researching driverless cars to adapt tothe trend of the car’s development.

Since2007, Carnegie Mellon University, Stanford University research institutes and Googlehave begun testing driverless cars on urban roads. In 2012, the Nevada MotorVehicle Authority issued a license plate driven by Google's smart drivingsystem, which also made the driverless cars begin to enter the eyes of ordinarypeople.

Thedomestic research of driverless cars started lately. In 2011, the Hongqi HQ3driverless car developed by the National University of Defense Technologycompleted a 286-kilometer high-speed full-range unmanned test from Changsha toWuhan. At the end of November 2012, the unmanned intelligent car developed bythe Military Transportation College successfully completed the highway test andbecame the first unmanned smart car in China which officially completed thehighway test. ^[2]

Althoughdriverless car technology has been implemented, most of the relatedtechnologies are still in the experimental and conceptual phase. Therealization of mass-produced driverless vehicles requires four phases: thedriver assistance phase, the semi-automatic driving phase, the highly automateddriving phase and the fully automated driving phase.^[3]

Driverassistance phase: The driver The driver has full control of the vehicle.Techniques at this stage include reversing images and parking sensors, lanedeparture warning system (LDW), frontal collision warning system (FCW), cruisecontrol system and blind spot information (BLIS) system. Compared with otherstages of development ^[4], the development of this stage is of maturity.

Semi-automaticdriving phase: The driver and the vehicle share the control of the car. Thedriver assistance control system monitors the operation of the vehicle in realtime and helps the driver to control the vehicle to some extent. Techniques atthis stage include adaptive cruise control, lane keeping assist systems, steepslope descent systems and automated parking systems.^[5]

Thehighly automated driving phase includes an adaptive cruise system and a lanekeeping assist system. ^[6]

AdaptiveCruise System: The adaptive cruise system is based on cruise controltechnology. During the running of the vehicle, a distance sensor (radar)installed in front of the vehicle continuously scans the road ahead of thevehicle, and the wheel speed sensor collects the vehicle speed signal. When thedistance of the current car is too small, the ACC control unit can becoordinated with the anti-lock brake system and the engine control system. Inorder to keep the vehicle at a safe distance from the vehicle in front.

LaneKeeping Auxiliary System: When the auxiliary system recognizes the markinglines on both sides of the lane during vehicle travel, the lane keeping assistsystem is in a standby state, and the camera in front of the vehicle canmonitor the left and right lane lines, and the vehicle approaches the markingline. At the edge, the system will alert the driver or issue a warning. ^[7]