Study On The System Of Vehicle Autonomous Driving Based On Double Antenna GPS

In order to fast, real-time, accurately control vehicle in the autonomous driving process of the vehicle, this article design the autonomous driving system of double antenna GPS based vehicle. Only accurately know the position and orientation information of vehicle, can the users know the position and orientation information of the vehicle or provide users with instructions to manipulate to achieve real-time control of the vehicle. Traditional north-seeking function is accomplished using gyroscope, but gyroscope is very expensive and it has a lot of restrictions to install and use. With the rapid development of carrier phase technology and digital signal processing technology,the real-time processing of GPS orientation measurement techniques become possible.Usually the orientation requires three parameters to determine: heading angle, pitch angle and roll angle, the three-dimensional orientation measurement requires at least three antennas. But this paper only need to measure the heading angle and pitching angle, so only two antennas are needed.This paper uses a dual antenna RTK-GPS positioning. RTK-GPS uses a dynamic real-time carrier phase differential method, which can get real-time centimeter-level positioning information in the field. Different antenna lineup will make the attitude determination accuracy of GPS different, we use the antenna which is placed in the front and ends of the rear longitudinal lines of the vehicle, the antenna and the longitudinal lines of the vehicle into a certain position angle to attitude determination.The achieve of vehicle orientation measurement is using the GPS coordinate information real-time calculate its pitch and heading angles in order to achieve the purpose of orientation measurement, at the same time, the precision of the positioning and orientation information will not reduce along with the accumulation of time.Control system is the key technology of the navigation system for autonomous vehicle.Information that the vehicle control system required is the lateral deviation and the heading angle compared between the vehicle and the desired trajectory, on this account, to decide the output of the front wheel angle, and to achieve the purpose of controlling the vehicle to travel along the desired trajectory. This article uses the fuzzy and PID control algorithm, namely fuzzy control first, in order to improve the systemdynamic response speed; Then adopts PID control, in order to improve the steady-state accuracy of the system. Make the system achieve optimal by adjusting the coefficient,thus to obtain the higher steady-state accuracy than pure fuzzy control, and faster dynamic response and smaller overshoot than PID control. Then tracking control the vehicle to make it run according to the expected path.The position and orientation determination method, based on the dual antenna RTK-GPS, implemented through theoretical analysis and experiments, such as work,improved the precision of the vehicle navigation control. First, we obtain an estimate,according to the relationship among state variables, and design a Kalman filter combining data from GPS, and then calculate the orientation of the vehicle according to the dual antenna coordinate information after filtering.