Design And Study On Cleaning Machine Using Magnetic Wheel For Plastic Greenhouse Roof

As an important part of modern facility agriculture,plastic greenhouse can meet people's demand for high-quality and high-yield agricultural products regardless of seasons and regions.However,due to the greenhouse normally is exposed to the natural environment like the sun,wind and rain for a long time,after 2 to 3 years of use,a mixture of dust and moss is likely to adhere to the film.The mixture is expected to decline in the transmittance of the film,inhibiting the growth of crops in the greenhouse and causing a decrease in yield and quality.Therefore,it is necessary to clean the roof of the greenhouse on a regular basis.Currently,there is scarcely any suitable cleaning equipment,So cleaning mainly relies on manual work which has the short comings of high cost,low efficiency,high risk factor and incomplete cleaning.Aiming at the difficult problem of cleaning the roof of multi-span plastic greenhouse with sunshade nets commonly used in southern China,this paper puts forward a design scheme of magnetic wheel type plastic greenhouse roof cleaning machine by analyzing the research status at home and abroad,aiming at the fact that the film covered by the roof can not be used as the focus and the steel truss of the greenhouse roof is circular arc.In this paper,the overall mechanical structure and control system of the cleaning machine are designed.Firstly,the multi-degree-of-freedom magnetic wheel walking mechanism composed of two magnetic wheels driven by walking motors on the left and right sides and the self-adaptive brush cleaning mechanism comprised of 8 disc brushes driven by cleaning motors and a parallelogram adaptive cleaning mechanism.are designed..Secondly,the driving force and the parameters of the walking motor are obtained by theoretical calculation and force analysis,the magnetic flux density and magnetic force are simulated by ANSYS,and the specific structure and size parameters of the magnetic wheel are designed,each magnetic wheel consists of two symmetrically arranged left and right half magnetic wheels(i.e.left and right half magnetic wheels)adapted to the arc shape of the steel truss circular tube.when the diameter of the magnetic wheel is 44 mm,the width is 24 mm,the inner diameter is 20 mm,and the coating angle is 45 degrees,the magnetic force of 62.34 N can be provided,so as to ensure that the cleaning machine can stably walk on the steel truss.Thirdly,the hardware circuit design and software program design of the control system are completed.The PIC18F46K22 chip is selected as the main control chip.Four DC deceleration walking motors are controlled by DRV8412 double H-bridge motor driver chip.The eight brush cleaning motors are controlled by IGBT.The current is detected in real time through the sampling resistor,and the cleaning machine is controlled through the switches on the control panel.The software program design mainly includes initialization,detection of battery under-voltage,setting the rotating speed of walking motor and cleaning motor,over-current detection of cleaning motor and walking motor,cleaning operation and work indication alarm lamp program.Finally,the cleaning machine is tested and debugged on the test platform.The corresponding weight value is taken as a comprehensive evaluation index to evaluate the cleaning operation after the uniform dimensions of light transmittance for evaluating the cleaning effect,time consumption for evaluating the working efficiency and water consumption for evaluating the water quantity required for the work are taken.Orthogonal experiments are applied to select the main factors influencing the cleaning operation: the weight of a single disc brush assembly,walking speed,brush rotating speed and water spraying quantity,and the walking stability of the magnetic wheel under different angle of osculation of the steel truss on the roof of the greenhouse and the cleaning effect of the cleaning machine are verified on the spot.The test results show that the cleaning machine using magnetic wheel for plastic greenhouse roof can achieve the expected design functions.The cleaning machine can walk smoothly and clean the roof on the steel truss with different angles of osculation when it is placed on the steel truss on the side of the trench and controlled by the switch on the control panel to walk and clean.When the weight of a single brush assembly is adjusted to 0.5kg and the water spray amount is 6L/min,the cleaning effect of the cleaning machine is the best when the matching walking speed is 3.5m/min and the brush rotation speed is 115r/min.The designed cleaning machine is tested on the spot under the optimal combination of cleaning factors.Compared with 20% to 35%transmittance before cleaning.the light transmittance can reach up to 80% after the cleaning.The cleaning effect is perfect and the system works reliably and stably.