Automatic Navigation Technology For Direct-seeding Planter For Rapeseed Based On BDS

Precision planter for rapeseed machine intelligent technology is a part of modern agriculture with “3S”,sensing,detection,automatic control,information processing technology development and intelligent agricultural machinery and equipment become the development trend of agricultural technology.The precision planter for rapeseed intelligent technology mainly includes navigation technology,loss sowing detection and real-time reseed technology.The planting linearity could be accurately controlled by the navigation technology,and rapeseed field is the maximize used maximize for the medium-term intelligent management of rapeseed and receiving mechanization to offer a standardized operating environment while reducing labor intensity such as rapeseed fieldwork and improve planting efficiency.The automatic navigation system of 2BFQ-6 type direct-seeding combined planter was designed includes positioning information processing method,navigation control method,front wheel steering control method and steering actuator.a navigation platform is set up for navigation experiments.(1)A BDS-RTK positioning system decoder are designed for receiving positioning information.It is the input of rapeseed broadcast navigation system.A Kalman filter are designed based on positioning system and IMU sensor for reduce the positioning error.The filter test uses the DBS positioning system to carry on the data acquisition and the Kalman filter.The results show that the standard deviation of the measured course data is 0.0654 rad,the standard deviation of the filtering result is 0.0326 rad,and the reduction of the horizontal direction is 50.15%.The deviation filter result data is smoother than the measurement of the lateral deviation data.(2)The straight-line driving control method is the core operation method of rapeseed broadcast machine navigation.Considering the fact that uncertain tire sliding,and uncertain pavement leads to trajectory of tractor could not be accurately described by kinematic model,a pure pursuit control method based on SVR inverse-model was proposed for agricultural machine navigation.This paper analyzed and determined the main structure and technical parameters of the method.The inverse-model of forward heading in tractor was established by using the method of granular support vector regression,and the corresponding relation function of kinematic theoretical curvature and actual curvature was obtained.The error of the output of the pure pursuit navigation model is corrected by inverse-model,thus the adaptability and dynamic performance of pure pursuit control method were improved.The path tracking experiments experimented on navigation system of the tractor and the pavement experiment results showed that the maximum of linear tracing pitch yaw roll error was less than 0.0614 m,when the speed of agricultural machinery was 1.2m/s and path length was longer than 125 m.Compared with the method of conventional pure pursuit navigation model,the pure pursuit control method based on SVR inverse-model has better linear racing performance.The speed adaptability test shows that the maximum lateral deviation and the average lateral deviation decrease by 42% and 50% on the speed of 0.7m/s to 1.4m/s,and under the condition of the high speed of 1.4m/s,reduce 48% and 59% respectively.Field experiment results concluded that the maximum lateral deviation was 0.0887 m,when the running speed of the tractor was 0.5m/s,and the controller of this paper significantly improve precision of field experiment.(3)A dual circle tangential line-tracking control method was designed to solve this problem,transmit between the linear tracking control when a navigation system of 2BFQ-6 type direct-seeding combined dual purpose planter for rapeseed work near the boarders of a field.Firstly a geometric relation formula of optimal connect linkage was found by quantitative analysis of the far targeted line searching path.Then the method of dual circle tangential line-tracking was constructed by the geometric relation formula,which created decision-making.According to the position and orientation of the tractor the matching control equations were selected by decision-making,and its calculations were used for tractor navigation control.Hence,a navigation system simulation model was established,it was used to achieve the purpose of optimizing model's parameters and verify the model performance.Path experiments were carried out on navigation system of the tractor.Experiments result showed that the overshoot of lateral deflection error response was less than 3%,Rise time and settling time of the response was smaller than 14 s and 18 s,respectively.When the speed of tractor was 0.7m/s,the initial lateral deviation error of the tractor center between the target line was 7m and the initial course deviation error was 90°.When it was compared with the method of conventional pure pursuit navigation model,the dual circle tangential line-tracking control method resulted in less values of overshoot and settling time.(4)Variable universe fuzzy controller has been designed for guaranteeing the quality of full hydraulic steering control on LX854-Dongfanghong tractor.The basis fuzzy controller is designed according to the characteristics of the system.The optimal basis fuzzy control parameters under different waveform and amplitude excitation signals have been obtained by using rotation up optimization method in the Simulink software.The adaptive fuzzy controller parameter turning changes the system to be an optimal control system by adjusting the universe in the basis fuzzy controller according to simulation results and using windowed Fourier transform and self-convolution to design online identification system.The experiment results on the LX854-Dongfanghong tractor indicated that the variable universe fuzzy controller is advantageous in steering performance compared with unvariable universe fuzzy controller.The measured 20° step response indicates that the regulation time was 2s,the largest steady error was 0.18°,the response without steady state oscillation.The measured sin response that the average delay was 0.3s.(5)An automatic steering control system of friction drive for agricultural machinery was designed to solve the problem that traditional automatic steering control system is too complex to be installed on 2BFQ-6 type direct-seeding combined dual-purpose planter.A four connecting rods parallel institution was used to develop the steering control device of friction drive for achieving fast mode switching function.Meanwhile the friction drive was simple operation and convenient installation by using the clamping installation method.The discrete simulation model of tire steering maneuver was established based on slip characteristics of the device.The simulation model was adopted to design the genetic algorithm optimizer,which could optimize the controller parameters online.The self-adaptation controller was adapted to control the automatic steering device of friction drive.The experiment on LX854-DFH tractor was used to analyze the performance of genetic algorithm optimizer.The experimental results showed that rise and regulation response time of the genetic algorithm optimization controller was decreased by 15% and 29% compared with the fixed parameter controller,respectively.The measured 20° step responses indicated that the average regulation time was 2.4s,the average absolute steady-state error was 0.197°,and there was no steady state oscillation,when the experimental results were recorded.(6)The automatic navigation platform of 2BFQ-6 type direct-seeding combined planter was designed includes positioning information processing method,navigation control method,front wheel steering control method and steering actuator for navigation experiments.The experiments of fieldwork and loop track were conducted in the modern agricultural science and technology experiment base of Huazhong Agricultural University.The experimental results show that compared with the conventional method,the maximum lateral deviation of the control method reduced by 0.0392 m,the average absolute lateral deviation decreased by 0.0192 m,the standard deviation increased by 0.0057 m.The straight line tracking part is in good connection with the curve tracking part in The path tracking experiment of loop track,and the average absolute lateral deviation of Linear tracking part was 0.167 m.The part of turn track is smooth with the average overshoot than 1%,the rise time is 11.4s and the adjustment time is 13.8s.Field experiment results showed that the navigation control system could be applied to automatic row-controlled operation of 2BFQ-6 type direct-seeding combined dual purpose planter for rapeseed.