Research On Automatic Control System Of Sowing Depth For No-till Planter

No-tillage sowing technology is an inevitable trend of China’s modern agricultural development,and it is an effective measure to protect the ecological environment and enhance grain yield.With the growing popularization of conservation tillage,no-tillage sowing technology has been developed rapidly.At present,the research on no-till technology in domestic has achieved some success,and substantially,the precise control of seeding amount has been realized.However,the study in the precise control of sowing depth is not deep enough.In this paper,through analyzing the domestic and foreign research dynamics of no-tillage sowing technology and sowing depth control,as well as combining the properties of Flex sensor,we carried out a research on the automatic control system of sowing depth for no-tillage planter,and completed the design of this system.In this system,we used Flex sensor as a deformation sensor of depth wheel to monitor the ground pressure of the planter unit to provide control signal for the adjustment of sowing depth.In order to use the Flex sensor correctly,we took a theoretical study and force analysis for the Flex sensor installed in the depth wheel,established the corresponding mathematical model,and extracted the relationships between the output signal of Flex sensor and the depth wheel deformation,and then we validated the accuracy of the model.No-till planter seeding depth automatic control system mainly includes two parts of the signal collector and the sowing depth controller.The signal collector is used to monitor the ground pressure of the planter unit by collecting the output signals of the Flex sensor in real time.The sowing depth controller can make control instructions according to the difference between the Flex sensor signals and preset value,and these control instructions can adjust the output air-pressure of the pneumatic transmission device to ensure that the planter unit has enough pressure on the ground,so as to achieve the purpose of sowing depth uniformity.In this system,two pieces of single chip microcomputer with type of STC12C5A60S2 are used as the core controller of the signal collector and the sowing depth controller,respectively.The transmission of Flex sensor data,where form the signal collector to the sowing depth controller,can be realized by a pair of wireless communication module with type of nRF2401.In addition,we use the voltage conversion technology to meet the needs of different supply voltage for different component.In order to test the response rate and performance of the system,the response tests and field tests were taken.The response tests result show that the response time of the system is about 0.43 s.And the field tests results show that the system is sensitive to the fluctuation and firmness of soil.The system can provide reliable performance of profiling and the success rate of seeding depth at which is over 90%,and it can meet the requirements of sowing depth precise control.