Research And Design Of Wheat Precision Seeding And Precision Control And Intelligent Designed System

Sowing is a key link in agricultural production.The quality of seeding machine sowing directly affects the growth and yield of crops.With the promotion of precision agriculture and the development of precision seeding technology,precision seeding has become a major component of modern agricultural seeding technology system.The use of precision seeding technology is an important means of large-scale production and realizing cost-saving and efficiency.On-line accurate detection of seeding volume is the key to precise seeding and precise control.However,there is still no effective measure for on-line real-time detection and precise control of seeding volume.In this paper,a wheat seeding detection system based on capacitance principle is designed,and the feedback control strategy based on intelligent monitoring sensor is studied.The main research contents of this paper are as follows:(1)Aimed at the problem of the precision detection of the wheat-planter seeding quantity,this paper develops a precise detecting system for wheat-planter seeding quantity based on the AD7745 analog to digital conversion chip.To guarantee the detection accuracy,every seed should be detected only once as far as possible when it passes through the parallel plate of capacitance sensor.Therefore,the structural size of the capacitance sensor is designed according to the detection resolution and the constraint relation between the seeding speed and the sampling frequency.Secondly,according to the requirements of detecting small capacitance change values and short processing time,the corresponding detection circuit is designed.Finally,the software part of the detection system was designed.(2)The relationship between capacitance value and the quantity of wheat seeds under two modes of single-seed falling and several-seed falling was investigated in detail.For the mode of single-seed falling,a differential dynamic threshold method was proposed to detect the number of wheat seeds.The experiment results indicated the maximum relative error was 1.538%.For the mode of several-seed falling,two treatments were proposed:(a)The least squares regression model between wheat seeds quantity and capacitance integral value was established for each 5 r/min increasing from 20 r/min to 55 r/min.The experiment results shown that according to the principle of the actual speed and the closest speed to select the corresponding regression model,the system has high detection accuracy for different seeding speed,and the relative error was between-2.16% and 2.22%.(b)A detecting method was proposed by changing the sampling period,in which the sampling period was reduced by 0.4 ms when the wheat-planter speed was increased by 5 r/min.The least square regression model established at 20r/min is still applicable for this case.The results show that high detection accuracy can be obtained for different seeding speed,and the relative error was between-2.26% ~2.17%.Consequently,the proposed system can achieve high detection accuracy under the different seeding mode and different seeding speed.(3)The design of the overall plan and control system of the precision seeder was carried out.The components of the precision seeder system: the main control system based on ARM controller,the speed measurement system based on CAN bus,the seeding quantity detection system based on capacitive sensor,the positioning system based on the Beidou,the seed wheel speed control system and the power module are detailed in design.Secondly,the subsystems are designed from two aspects: hardware and software.Finally,according to the requirements of monitoring parameters and input external parameters,the human-computer interaction interface of the wheat precision planter control system was designed.(4)An intelligent decision-making system for wheat precision seeding was developed.The wheat precision seeding intelligent decision-making system is a closed-loop system.According to the digital map and seeding prescription map of the planter working area,the theoretical seeding amount is extracted,and the walking speed of the tractor is obtained according to the Hall sensor.Then calculate the theoretical seeding speed of the seed meter.In this paper,a feedback system based on intelligent monitoring sensor is designed.The fuzzy control and PID are used to adjust the rotational speed of the motor in real time,so as to achieve the precision seeding.