Evaluation And Control Of Uniformity Of Spray Distribution In Spray Machine

In this era of agricultural modernization,the input-output ratio of agriculture is a measuring standard to determine whether a country is a large agricultural country or not.The production of cotton and rice in China ranks first in the world,however,both the planting area and the use of pesticide are also in the first place of the world.At present,the conventional artificial spray is still the main type of spray in our country,which has the character of high work intensity and lower efficiency.In addition,the spray distributed on the surface of the leaf is uneven and may even fall to the ground resulting in the secondary pollution of the soil and direct or indirect injury to human.The desired spray effect can not be obtained.Therefore,with the policy of national sustainable development,it is of great significance to develop a new kind of spray machine with high efficiency and better spray effect for reducing the use of pesticides,repairing soil environment and ensuring quality and safety of agricultural products.In this thesis,the effect of spray parameters on the spray distribution evenness in the process of agricultural operation is mainly studied.The ideal spray distribution is achieved by controlling the parameters of the spray.Firstly,according to the known sample data,the relationship between influencing factors and spray distribution evenness is confirmed by BP neural network modeling.Then the inverse modeling method of BP neural network is used to determine the only corresponding influence factor parameter value among the given spray distribution evenness and the n-1 influence factor values.And the influence factor value determined is set as the controlled variable in the process of the machine operation.In Chapter4,taking the spray pressure as an example,it is selected as the controlled variable and other factors are set as fixed quantity.Selecting the John Deere 4130 sprayer as the controlled object,a pipeline pressure system model is established to obtain the relationship between the centrifugal pump speed and the spray pressure.Then,the linear quadratic optimal control algorithm is adopted.Through the regulation of the speed,the spray pressure can maintain the pressure setting value which is correspond to the evenness of the specific spray distribution.Some other machines use piston pumps instead of centrifugal pumps.Therefore,the spray pressure system consisted of piston pump is analyzed.The linear quadratic optimal control is adopted to change the displacement of the direct drive valve core by adjusting the voltage,andthen the spray pressure control of piston pumps is realized achieving even spray.The simulation of pressure control is accomplished in MATLAB,the results show that the qucik tracking of the pressure value is realized.