Design of motor-driven precision seed-metering device with improved fuzzy PID controller for small peanut planters

Traditional passive ground wheel drive of peanut planters has displayed poor high-speed seeding performance and the slippage caused in case of sticky and wet soil.Given this,an integrated electric-driven precision seed metering device and controller were designed,which features the application of improved fuzzy PID algorithm.Based on a small peanut planter with one ridge width and duplicate rows,the servo motor drive is used to replace the traditional passive ground wheel.In addition,the satellite speed measurement is employed to complete the electric driving and controlling modification of the seed meter and precise seeding control.A working process mathematical model for the peanut metering device was established to conduct motor speed and field tests which aim at comparing performances between the conventional and the improved fuzzy PID controls.The motor speed trial shows that the average error of the actual speed of the improved fuzzy PID motor was±1 rad/min,and the coefficient of variation was less than 1%.Against the conventional one,it can better suppress overshoot and improve the response speed.The stable output speed can still be obtained even in case of step changes.Field tests show that when working at medium and low speeds,the qualified rate of plant spacing was greater than 98%,and the rate of missed sowing is<2%;while working at high speed,the qualified rate was greater than 94%,and the rate of missed sowing was less than 4%.The average plant spacing qualification rate of the seed device increased by 6.72%;compared with other electric-driven peanut seed meters,the plant spacing qualification rate increased by 4%during high-speed sowing.In summary,this study has provided an effective technical reference for high-speed precision planting of peanuts.

Design of variable-rate liquid fertilization control system and its stability analysis

Variable-rate technology(VRT)has been paid more attentions by farmers in an attempt to match inputs to local growing conditions efficiently.Farmers in every country are highly encouraged to adopt this practice rather than uniform-rate application(URA).However,the standard methods and design used to quantify application accuracy for VRT remain lacking.Therefore,a variable-rate liquid fertilization control system was designed to meet accurate fertilization demand.The designed control system could enable the real-time proportion and mixture of three kinds of liquid fertilizers,namely,N,P and K,in accordance with decision support subsystem.The task controller reads related information and sends such data to the control system,which is responsible for fertilization operation.The controller could realize liquid fertilizer adjusting through the electromagnetic flow control valves.A high-precision flow meter could measure the fertilization amount,which is sent as feedback to the controller to form a closed-loop control system based on the improved proportional-integral-derivative(PID)control algorithm that could enhance the stability and accuracy of precision variable-rate liquid fertilization control systems.Comparisons between the actual and planned application rates indicated good performance for both static and field experimental trials.Mathematical models and transfer functions for some functional modules were then constructed by classical theories to derive a system characteristic equation.To verify the static and dynamic performances,the control system was simulated using the Simulink module on Matlab.Results showed that the variable-rate fertilization was in accordance with the planned data and that the signal trace effect was good.The error was less than 5%for fertilization amount and fertilizer proportion,respectively,and the control response time was 6 s.