Research And Design Of Vehicle Positioning System In Precision Agriculture

The development of Chinese agriculture has gone through the transformation from traditional homework to mechanical operation.At present,although the degree of automation of agricultural machinery is still not high,the era of automatic driving in the future is bound to come.To realize the automatic driving of agricultural machinery,the problem of positioning and navigation is the first to be solved.The positioning navigation of agricultural machinery is different from the positioning and navigation of urban vehicles.The advantage of urban environmental navigation and positioning is accurate road map matching,which can correct the positioning results.Map matching is generally not suitable for farmland environment.The future agricultural machinery autopilot is necessarily accompanied by the joint establishment of precision agriculture.In precision agriculture,wireless sensor networks are usually used to collect farmland and crop information in real time.Wireless sensor networks also provide another possibility for the precise positioning and navigation of agricultural machinery.The adoption of RTK-GPS technology is the most common solution to the problem of agricultural machinery positioning.This technology is the observation of satellite carrier phase,the positioning accuracy is very high,but the need to set up a base station and high price makes it difficult to vigorously promote.Therefore,this paper studies the vehicle positioning system in precision agriculture,designs and implements the GPS/INS/WSN integrated positioning system with low cost and high accuracy.Firstly,the common localization technologies in wireless sensor networks are studied,including ranging based location method and location free method.After analyzing the advantages and disadvantages of this paper,considering the complexity of the algorithm,the positioning accuracy and the requirements of the hardware,the RSSI based distance measurement method is selected to fuse the integrated positioning system in this paper.Secondly,the research of wireless signal propagation loss model of farmland environment,according to the measured RSSI in similar farmland environment values under fitting parameters of wireless signal propagation loss.In view of the received RSSI value fluctuation problem,this paper uses the Gauss filter method to filter,and then uses the fitting path loss parameters to carry on the wireless sensor network positioning test.The test results show that wireless sensor networks have better localization performance.Then,MATLAB software is used to simulate the performance of GPS/INS/WSNintegrated navigation.As a contrast,the simulation of GPS/INS integrated navigation system,WSN/INS integrated navigation system and GPS/INS/WSN integrated navigation system are carried out respectively.The GPS/INS/WSN integrated navigation system uses the INS as the reference system to establish a federated Calman filter.The simulation results show that the GPS/INS/WSN integrated navigation system has better performance than the single GPS/INS and WSN/INS integrated navigation system.Finally,based on the requirement analysis of GPS/INS/WSN integrated positioning system,a set of GPS/INS/WSN vehicle positioning system is designed and implemented,including the hardware design of the system,the ARM program design and the software development of the ZigBee module.Then,the upper computer program is designed and implemented by C++ to monitor the vehicle positioning system.The test results show that the integrated positioning system designed in this paper can improve the positioning accuracy of agricultural machinery and meet the precise positioning requirements of agricultural machinery.