| Advanced Assisted Driving System(ADAS)uses sensors on the car to collect and analyze the data of the environment around the car,and inform the driver of possible dangers in advance.These sensors need to be re-calibrated after being replaced due to aging and damage.The safety and stability of auto-driving depend on the accuracy of sensor calibration.At present,there are many kinds of automotive ADAS systems,and the sensor calibration methods are different with different types and numbers of sensors.It is of great significance to design a calibration system with high efficiency and wide application range for the automobile fault diagnosis industry.In this paper,the joint calibration technology of vehicle sensors is studied,and the hardware design and software development are carried out,which can be used for the calibration of ADAS advanced driver assistance system.Based on a large number of literatures and field experiments,aiming at the traditional camera calibration,a new target is adopted to complete the camera calibration.Combining the advantages and disadvantages of others’ calibration board design,a new calibration board is designed,and the calibration of laser radar and the joint calibration of camera and laser radar are completed through the calibration board.The main contents of this paper are as follows:(1)Research the 3D visual computing space model and the measuring principle and model of the camera,and provide theoretical basis and technical support for camera calibration.Based on the theoretical basis of Zhang Zhengyou’s calibration method,single camera calibration and dual camera calibration are completed by using a circular target,and the distortion is corrected by considering the influence of distortion factors on the calibration results.(2)The measurement principle and model of laser radar and millimeter wave radar is studied,to provide the theoretical basis for calibration.According to the requirements of this subject,a new calibration device is designed,and the calibration of laser radar and the joint calibration of camera and laser radar are completed by using this calibration device.In the process of calibration,the point cloud is acquired according to the designed calibration device,and the point cloud is screened and the calibration result is optimized by the least square method and LM(Levenberg-Marquard)algorithm.Time synchronization is used to solve the problem of inconsistent data acquisition time of different sensors.The experimental results show that the newly designed calibration board can complete the calibration method more efficiently,and the optimization algorithm improves the accuracy of calibration.(3)With the help of horizontal calibrator and plumb tool,the calibration of millimeter-wave radar and the joint calibration of camera and millimeter-wave radar are completed.(4)Design the C++ upper computer calibration program,complete the image acquisition and processing,the acquisition and selection of point cloud in lidar calibration and the optimization of calibration results.The upper computer and the lower computer combine software and hardware to complete the analog detection of vehicle sensor calibration.The test results show that the way of combining hardware circuit with software is faster and wider than the traditional way.(5)Design the hardware circuit diagram of the lower computer,using the core chip to replace some electrical components,and design the power circuit,CAN bus drive circuit,K-line drive circuit and pin switch circuit in the hardware circuit of the lower computer. |
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