# Design and Test of Automatic Feeding Device for Substrate Filling
## 1 Introduction  
Container seedlings have the advantages of a short seedling cycle and a high survival rate, and container seeding is the main seedling cultivation method in citrus seedling cultivation bases in China [1, 2]. The developed citrus seedling bowl filling and transferring machine can effectively fill and transfer seedling bowls, with a single filling time of about 60 s and a filling number of 105 bowls [3]. This is a significantly higher rate than the manual filling rate of 60-80 bowls per person per hour, and it greatly improves the efficiency of seedling raising. However, the installation height of the silo of the filling and transporting machine is relatively high, which makes it time-consuming and laborious to manually add matrix soil to the silo [3]. To facilitate the work of the citrus seedling bowl filling and transferring machine and enable its automatic feeding process, it is necessary to design an automatic feeding device to replace the manual completion of the barn substrate soil adding operation, essentially realizing the mechanization and automation of the citrus seedling process, thereby further promoting the development of the Chinese citrus industry.  
The research into foreign loading devices commenced at an early stage, with a greater investment of funds. Following a lengthy period of technical accumulation, automation, and mechanization, the degree of development is now higher, and the devices are now developing in the direction of intelligence. The German company Haller has developed amechanical arm garbage can recovery device [4; 5]. The driver in the cab is able to grasp garbage can at arbitrary angles and recover them in the bucket operation. The Dutch company JAVO has developed automatic pot-filling equipment [6; 7; 8; 9], which is equipped with a special automatic substrate soil feeding device, with a filling efficiency of up to 4000 pots/h. Foreign feeding devices tend to be expensive and specialized for specific working conditions, and therefore cannot be used in the main seedling cultivation method in citrus seedling cultivation bases in China. Chinese feeding devices originated in the last century after a lengthy period of development. Currently, there are a variety of devices, including trash bucket lifting and turning devices, screw feeders, bucket elevators, belt conveyors, and others. However, the direct use of these models for citrus seedling bowl filling transfer machine bins for substrate soil addition operations often results in unclean discharge, machine jamming, and other issues [10; 11; 12].  
In conclusion, this paper presents the design of an automatic loading device for a citrus seedling bowl substrate. The device was created using Solidworks (2018) to model the overall structure in three dimensions and the Adams (2020) to simulate the loading process. The loading process was optimized using a multi-objective optimization of the flip frame structure. Finally, the test prototype was processed for performance testing. The findings of this study can serve as a foundation for the development and optimization of subsequent automatic loading equipment for citrus seedling bowl filling substrates.