Design And Experiment Of Self-locking Precise Feeding System For Small Group Pregnant Sows

At present,pregnant sows breeding in China mainly adopts two models: limiting bar and group housing.However,the limiting bar has been banned by EU and the group housing is gradually becoming a breeding trend.Among them,small group housing has become one of the main breeding models suitable for China,which can guarantee the freedom of movement of sows and at the same time reduce the fighting between sows,and improve the reproductive performance and service life of sows.To address the problems of existing feeding system for small group pregnant sows,such as pigs climbing and so on,causing the feeding passage door to close abnormally,thus causing the sows unable to feed,and the self-locking performance of the system cannot be guaranteed after the pneumatic door is powered off or damaged.In this study,a self-locking precision feeding system for small groups of pregnant sows was designed,which achieved self-locking of feeding passage and had functions such as identification,precision feeding and residual feed detection.The main work and conclusions of this paper are as follows:(1)Design of the overall solution.The requirements of the precision feeding system for small groups of pregnant sows were analyzed in six aspects,including feeding quantity requirements,self-locking,identification,precise down-feeding and down-watering,feeding strategy,system reliability and stability.The RRRSR(R is the revolute pair,S is the spherical joint)was determined and adopted for the overall mechanical structure of the self-locking fully mechanical feeding passage.The STM32F407ZGT6 main control chip was used as the control core to design the overall hardware structure and the software architecture was designed based on the Free RTOS operating system.(2)Design and analysis of mechanical systems for feeding systems.A self-locking fully mechanical feeding passage was designed,including front and rear doors,intermediate links and damping devices.The principles of linkage and self-locking of the front and rear doors were also analyzed,which can achieve undisturbed feeding of a single sow.The precise feeding device was designed,including the hopper,the down-feeding structure,the down-watering structure and the residual feed detection structure,and the structural parameters of each key component were determined.(3)Simulation analysis of kinematics and dynamics of self-locking feeding passage.A 3D model of the overall mechanical structure was constructed using SOLIDWORKS and kinematics and dynamics analyses of the feeding passage were carried out to optimize the length of the rods and the forces required to push the front and rear doors.The maximum angles of rotation of the front and rear doors of the feeding passage were calculated to be80.00° and 51.40° respectively.With a minimum height above the ground of 189.06 mm and 1077.57 mm when the rear doors were closed and opened,respectively,as well as a theoretical maximum force of 19.46 N and 30.22 N required to push the front and rear doors respectively.The results of the simulations confirmed the feasibility of the feeding system on a theoretical level.(4)Design of control system for feeding system.The core circuit of the control system was designed and the required functional modules were selected to design the system’s power module circuit,UART communication module circuit,data storage module circuit,down-feeding and down-watering module circuit and residual feed detection module circuit.At the same time,software was developed for the individual functional modules to ensure that they can work properly.Task scheduling was carried out with the Free RTOS so that each module can run in a coordinated manner.Finally,the human-machine interface was designed to enable sows entry and exit station management,feeding management,data query,function detection,abnormality query and system setting,which improved the visualization and operability of this feeding system.(5)Prototype performance test.Tests were carried out on down-feeding accuracy,down-watering accuracy,the force required to push the front and rear doors and self-locking stability.The test results showed that the maximum relative error of the system was no more than 4.31% for a single cycle of down-feeding and no more than 2.36% for a single downfeeding.The maximum relative error of the system in the range of 100 m L to 300 m L of down-watering did not exceed 1.80 %.At the same time,the maximum force required to push the front and rear doors was approximately 25.0 N and 37.5 N respectively,and the feeding passage was self-locking and stable at the dead point,which can meet the demand of climb prevention.Sows feeding test showed that sows can easily push the front and rear doors of the feeding passage,ensuring that a single sow can feed without interference.In addition,the system had a 100% success rate in identifying the sow.The combination of the residual feed detection function and the precise down-feeding and down-watering function can control whether the system can feed or not according to the feeding information of different sows,thus achieving the purpose of monitoring the amount of feed in the feeding tank.The system can record the daily feeding information of sows and display it through the human-machine interface,which proved the feasibility and stability of the precision feeding system for small groups of gestating sows.