| Plant protection technology by using unmanned aerial vehicle(UAV)can effectively improve the mechanization level of hilly area,and has a promoting effect on the modernization and intelligent development of agriculture.The effect and efficiency of plant protection operation by UAV are directly related to the cost of agricultural production and the yield and quality of crops,which affects the enthusiasm of farmers to use UAV for production operations.For the region with complex terrain such as hilly mountains,it is difficult to carry out plant protection by manual operation,and the efficiency and effect of operation cannot be ensured.Therefore,it is of great significance to plan the operation path of plant protection UAV in hilly area,which can improve the efficiency of plant protection operation and expand the scope of plant protection operation by UAV.This paper aiming at the deficiency of the existing method of operation path planning for plant protection UAV,and carrying on the research of path planning for plant protection operation on the basis of analyzing the operation demand of plant protection by UAV in hilly area.According to the three-dimensional motion characteristics and energy consumption status of UAV,the constraint parameters of energy efficiency for UAV's three-dimensional motion were obtained,and the optimal energy consumption path planning method for plant protection operation by UAV based on the constraint of energy consumption was explored.The main research contents and conclusions of this paper include:(1)The three-dimensional motion model of UAV was constructed.In order to construct the three-dimensional motion model of UAV,an electric four-rotor UAV for test was designed and built,The UAV was mainly composed of body frame,drive motor,electronic speed controller,propeller and flight controller.Its diagonal motor distance was650mm,and the overall flight model was"X"type.Secondly,the 4 basic flight attitudes and the transformation relationship of the moving coordinate system were analyzed for the built UAV,and the force analysis of the UAV motion process was completed based on this,and the simplified force model of UAV's three-dimensional motion was constructed on the basis of reasonable assumption,and the horizontal flight energy efficiency coefficientK_f,the vertical rise energy efficiency coefficientK_r,the vertical descent energy efficiency coefficientK_d and the yaw energy efficiency coefficient K_?of UAV's motion process were proposed,which can provide parameter support for further path planning.(2)The devices for testing UAV were designed and built.The energy efficiency testing device and the yaw energy consumption testing device were designed and built respectively,and the upper computer software which was used to display and store the testing data in real time was developed based on LabVIEW environment for each device.The energy efficiency testing device was mainly composed of thrust acquisition module,power acquisition module,single-chip microcomputer,wireless module and test platform,and the yaw energy consumption testing device was mainly composed of angular velocity sensor module,power acquisition module,single-chip microcomputer and wireless module.The accuracy of testing device was overall improved through the calibrated experiment.The sampling rate of energy efficiency testing device was 80Hz,the thrust measurement range was 0~196N with the accuracy of 99.88%,the current measurement range was 0~90A with the accuracy of 99.00%,and the voltage measurement range was 0~28.5V with the accuracy of 99.70%.The sampling rate of yaw energy consumption testing device was100Hz,and the measurement accuracy of yaw angle was 98.10%.(3)The relationship model between power and thrust of UAV was constructed.The UAV's power data and its corresponding thrust data were obtained by using the testing device to test the UAV,and the relationship model was fitted based on those data,the correlation coefficientR~2 was 0.9894,and the fitted model was further verified by the heterogeneous verification method,the correlation coefficientR~2 of verified was 0.9967,the slope of the correlation curve was 1.001 and the longitudinal intercept was 0.0434.By analyzing the error between the values calculated by the fitted model and the values measured by testing device,the maximum absolute value of the relative error was 5.99%,which indicated that the established relationship model between power and thrust of UAV had a high accuracy.(4)The optimal energy consumption operating path of UAV based on simulated annealing algorithm was planned.The three-dimensional terrain model of mountain orchard was constructed based on the aerial image obtained by UAV,and the target point model for UAV's operation was constructed by using the obtained three-dimensional terrain data.The UAV's flight energy efficiency coefficients under different loads were obtained based on the relationship model between power and thrust of UAV,and then the path planning problem was translated into traveling salesman problem by combining the proposed target point model and the UAV's flight energy efficiency coefficients,and the optimal energy consumption path of UAV under different constant load and real-time changing load were achieved by designing the corresponding simulated annealing algorithm.The results shown that when the load changes in real time,the optimal energy consumption path can save energy by 11.72%compared with the shortest path,and save energy by 32.04%compared with the conventional path;when the loads were constant,the optimal energy consumption path can save energy maximum by 5.47%and minimum by0.86%than the shortest path,and can save energy maximum by 30.16%and minimum by26.76%than the conventional path.It is shown that the simulated annealing algorithm can plan the UAV's operating path based on the energy consumption constraints and has a good effect. |
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