| China is one of the countries with the largest apple cultivation area in the world,with a planting area of up to 667,000 hectares.As a large apple exporter and consumer,the output accounts for more than half of the world's total output.In recent years,the orchard weeding machinery has developed rapidly.Nevertheless,the orchard planting model is constantly changing and types of domestic orchard special-purpose weeding machines are few,which mostly are expensive imported products and could not meet the urgent demand of orchard weeders,resulting in low weeding rates.Affects the growth of fruit trees and fruit quality,and also delays the mechanization of weeding in orchards.Based on the field research in the apple producing area of loess plateau in northwest China,the functions and shortcomings of existing orchard weeding machinery were understood.According to the investigation data and horticultural requirements,an orchard obstacle avoidance and weeding robot is designed.To some extent,it can assist people a lot such as completing weeding operations,reducing labor intensity,reducing pesticide use,protecting the orchard ecological environment,and improving the automation and intelligence of orchard management machinery to a certain extent.Regarding the development of new orchard obstacle avoidance and weeding robots,the main design and research contents are as follows:(1)Based on the characteristics of northwest orchards and horticultural requirements,determine the size of the whole machine,and design the overall structure of a multifunctional orchard obstacle avoidance and weeding robot,which mainly includes a front-type weeding device,a double-sided obstacle avoidance mechanism,a lifting mechanism,a steering mechanism,a driving device and handrail mechanism,etc.With completing the overall assembly and interference inspection,a3 D model of orchard weeding robot is established by the Solidworks.(2)The installation parameters of each electric push rod of the obstacle avoidance mechanism and lifting mechanism is obtained by performing theoretical calculations on the obstacle avoidance mechanism and lifting mechanism of the weeding robot.The inclination angle and the minimum turning radius of the whole machine are calculated and determined to verify the design passability of the wholemachine.Based on ANSYS Workbench,a finite element analysis of the weeding device of the weeding robot was performed to obtain the vibration pattern,natural frequency and maximum deformation position of the weeding obstacle avoidance device.The maximum deformation is 0.43 mm,and the maximum deformation stress is 38.629 MPa.(3)Based on the dynamics simulation software ADAMS,a motion simulation analysis on the obstacle avoidance mechanism of the weeding robot is performed,and the telescopic amount and force of the electric pusher of the obstacle avoidance mechanism,motion trajectory,speed,and acceleration under different orchard row distances are obtained.(4)The control system of the weeding robot is designed.On the premise of meeting the functional requirements,Siemens S7-200 smart series ST30 PLC is used.The hardware is designed to include the detection circuit,the drive circuits for each motor,and the drive circuit for electric actuators.The software is designed for PLC programming and touch screen control interface design,and debugging.By completing the above research content,a multifunctional orchard obstacle avoidance and weeding robot with a short shape,a low center of gravity,a small turning radius,an adjustable width,and an automatic obstacle avoidance function was designed.It is suitable for the traditional orchard planting model and the new type of short orchards which are densely planted to achieve automatic weeding in orchards and improve weeding efficiency. |
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