| With the rapid development of precision agriculture in China,automated and high-resolution crop phenotypic information collection devices are greatly significant for managing environment and nutrient conditions based on in-depth analysis of crop phenotypic information.Currently,crop phenotypic information collection devices in greenhouse mostly use fixed imaging sensor positions to solve the problem of multi-angle and multi-directional collection of phenotypic images by rotating crops or increasing the number of imaging sensors.However,existing devices generally have problems such as large volume,high costs,and the impact of crop growth on the quality of captured images is not considered.Therefore,a small hand-held plant phenotypic information collection device with low costs,resource and energy consumption based on lettuce growth characteristics(crown diameter and plant height)in greenhouse was designed,and the application effect of the device was verified in this paper.The working content and results are as follows:(1)Based on the determination of the actual operating conditions and the requirements for photographic functions,the overall structural design of the crop phenotype information acquisition device is carried out.The main structure of the device includes: horizontal movement mechanism,lifting mechanism,and image acquisition mechanism;In the horizontal movement mechanism,two sets of gear-rack modules are used to bear all key mechanisms and regulate the horizontal position.In the lifting mechanism,the lead screw module is used to regulate the height of the image acquisition mechanism.Both modules accurately adjust the displacement amount through precise control of the number of rotation steps by stepper motors.Digital servos are used to control the shooting angles of RGB industrial cameras.(2)Hardware selection for the control system of the facility lettuce phenotype information acquisition device was completed.The S7-200 SMART PLC controller is used as the main control device,and two 57HB76 A stepper motors are used to regulate the horizontal movement and vertical displacement of the lifting mechanism respectively.The DSSERVO-RDS3225 dual-axis digital servo and industrial camera are configured together,and the drive in five directions of the digital servo is set up to control the camera shooting angle.The JHSM500 s industrial camera is selected with a JHHF0420 industrial camera lens to form the imaging sensing system of the device.On the basis of the automatic running program,a TPC7062 Ti embedded integrated touch screen is added as the display module,which is used to realize manual control requirements such as manual control adjustments of the device,selection of the target lettuce variety,and setting the cultivation start time.(3)The software of the control system was designed based on crowns and heights growing characteristics of three types of lettuce.Based on crown width and plant height growth data of Italian lettuce,Cream lettuce and Crisphead lettuce from the experiment,a basic growth model for various varieties of lettuce under suitable growth conditions was established through cultivation experiments.These models were used to establish a displacement calculation method for the lifting mechanism and horizontal moving mechanism of the device,the software of the device control system was completed by using STEP 7-Micro WIN SMART programming language,and the device functions were realized.(4)Cultivation experiments were carried out to collect the phenotypic image information of three types of lettuce under different nitrogen application conditions during the growth cycle(30 days)using this device.Conventional image processing technology was used to extract related information such as the external shape and color characteristics of the lettuce leaves,and to verify the application effect of the device.The results showed that the phenotype images obtained by this device could be accurately recognized for differences in canopy width,plant height,and canopy projection area using conventional methods.The linear relationship coefficient(R2)between the extracted value and the actual value was above 0.99,and the recognition effect was not lower than that of complex image processing technology.This indicates that the device was able to accurately extract physical parameters of the appearance phenotype of lettuce and demonstrate the advantages of the device design output.Furthermore,the color feature values S are shown to have a correlation coefficient(R)of 0.82 or higher with SPAD,above-ground fresh weight,and nitrate content,which provides effective and reasonable theoretical and practical technical support for further study of the dynamic growth and development process of lettuce.Finally,the device’s cost advantage was determined by calculating the total cost of the device production process and comparing it with the cost under the same functional requirements setting,which is consistent with the original intention of designing a low-cost,low-power device. |
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