Design Of Hardware-in-the-loop Simulation Test Platform For Tractor Operation Assisted Navigation System

Tractor work-assisted navigation technology as well as its equipment development and application are the main research topics of intelligent agriculture.The working conditions of tractors are characterized by complexity and diversity.In order to improve the quality of fanning operations,the navigation systems are required to cope with complex practical applications.In the development of the navigation system,a hardware-in-the-loop platform for rapid debugging and testing is required,which improves the efficiency of development and test.This paper is based on the National Natural Science Foundation of China,which integrates and develops the hardware-in-the-loop testing platform for tractor work-assisted navigation systems.The research has important theoretical and practical value.The main content of the thesis are as follows:(1)The tractor operation navigation hardware-in-the-loop test platform function and its architecture were determined,which based on the requirement of tractor operation navigation,the research team tractor navigation system prototype and the domestic and international hardware-in-the-loop test platform research literature.(2)The hardware-in-the-loop simulation test platform was integrated development.The steering system,road-sensing simulator and wheel steering angle sensor of the test platform were selected,arranged and installed.The steering system adopted the double cross-shaft universal joint,and the space constant velocity transmission principle was studied.The installation and layout on the test platform were simulated and tested.A automotive electric power steering system was selected,and the simulation of the steering feeling was realized based on its resistance motor.Test benches,steering limit devices and equipment connections were designed based on profiles.The test platform is easily to perform indoor,outdoor and mobile testing.(3)The serial communication protocol of the combined sensor and the communication protocol of the steering motor CAN were analyzed.The serial bidirectional communication data between the combined sensor and the controller was extracted,and the data meaning of the corresponding position of the communication frame was determined,which was according to the combined sensor input condition and the controller display data.The CAN signal of the steering motor control input was extracted,and a typical path was set on the controller,and the definition of the CAN signal data frame was comprehensively determined.(4)The virtual test system was designed based on the LabVIEW.The test system consists of a data collector and software.The data collector selects the NI cRIO controller and its C module,and the software was based on the Lab VIEW development environment.Performance tests of combined sensors and steering motors were performed.The test results show that the combined sensor has a positioning accuracy of up to 2 cm in static state and continuous stable positioning performance in dynamic state.The steering motor has better steering accuracy,response time and up to 4.3 N·m stalling torque.This paper designs a test platform for tractor-assisted navigation system,also carries out related basic research.The platform can provide an effective means for the research of navigation algorithms and low-cost navigation system development of subsequent tractors under different complicated conditions.