Research On Ultrasonic Positioning Technology For Charging Port's Pose Of Electric Vehicle

With the continuous popularization of automotive automation technology and the improvement of high-power charging technology,the automatic charging technology of electric vehicles is developing rapidly.At present,the automatic charging process mainly uses the visual system to realize the positioning of the charging port of electric vehicles,but the system is expensive to arrange and not adaptable to rain and fog weather.In order to promote the popularization of automatic charging technology of electric vehicles,it is urgent to develop a positioning system with low cost,high precision and good environmental adaptability.Therefore,it is of great theoretical significance and engineering application value to study ultrasonic measurement technology to realize low-cost and high-precision three-dimensional reconstruction and positioning of charging port position and posture.Through the research and simulation of ultrasonic field characteristics,the selection basis of ultrasonic sensor is obtained.Based on the research of the ultrasonic positioning technology,infrared signal is used as a time reference signal of ultrasonic distance measurement scheme,designed the "three-transmitter-three-receiver" ultrasonic positioning node layout,and established the posture positioning system based on coordinate system,determined the 3d coordinates and pose of electric vehicle charging port and verified the correctness of the algorithm.Through the error analysis of the attitude algorithm,the layout of the ultrasonic location receiving node is determined.The high precision ultrasonic ranging module is designed,and its stability is verified by logic analyzer.The real-time sound velocity measurement module is studied to eliminate the error of ultrasonic sound velocity measurement caused by temperature and humidity sensor.The control circuit of the positioning system's transmitter and receiver is developed,which made the system work stably.The control program of the key chip,the main program of ultrasonic propagation time measurement and the RS232 serial communication program are written,so that the system can successfully complete pose positioning.QT-based software is developed to display the position and posture of upper computer.Through the improved mean filtering algorithm of experimental data processing,the accuracy of experimental data filtering is improved by 16 %.The axial and radial linear ranging experiments were carried out on the ultrasonic ranging module within the range of 200 ~ 1200 mm.The experimental results showed that the accuracy of axial and radial linear ranging was ± 0.30 mm and ± 0.47 mm respectively.Verification experiments were carried out on the positioning system in indoor environment anddifferent outdoor environment.The results showed that the three-dimensional coordinate measurement accuracy of the positioning system could reach ± 1.93 mm,and the Angle measurement accuracy could reach ± 2.85 °,reaching the expected target of the design.