Rice transplanter is an inevitable technology for rice farming. In Korea, rice transplanter is almost 99.9% mechanized. In recent year, rice transplanter is spreading out overseas with sophisticated facilities. However, the export of domestic rice tra...
Rice transplanter is an inevitable technology for rice farming. In Korea, rice transplanter is almost 99.9% mechanized. In recent year, rice transplanter is spreading out overseas with sophisticated facilities. However, the export of domestic rice transplanter has decreased compared to previous years due to the backdated technologies. This is why the mechanized rice transplanter should modify with advanced technology like a proportional valve to hold the global share market of the rice transplanter. Therefore, the goal of this study is to develop the simulation model of the automatic planting depth control system of a rice transplanter using proportional valve. In this study, the PID control law was also studied to control the hydraulic system of rice transplanter. Actually, two PID control algorithm was developed: i) to control the displacement of actuator ii) to compensate for the viscous effect on the hydraulic system of a rice transplanter. Ziegler-Nichols (Z-N) methods were used to determine the PID coefficients. The simulation was conducted for three ISO standard hydraulic oils. Validation test for both control laws was conducted by performing proportional valve test bench for the same hydraulic oils. The viscosity of the hydraulic oils was calculated at its reference temperature. The lowest overshoot and settling time were found at K_p: 5.24, K_i:4.39, and K_d:1.34 for the position control without considering viscosity, and K_p= 200 T_i=2.52 and T_d=0.63 for position control considering viscosity at the damping ratio 0.8. The simulation results of the position control without considering viscosity show that the pressure of the proportional valve is proportional to the decreasing rate of hydraulic oils viscosity. This result indicates that the position control without considering viscosity cannot able to control the viscosity effects. In case of position control considering viscosity, results were found that the maximum pressures of proportional valve for 1 A and 2A supplied current was the same for both simulation and experiment, calculated around 15.40 bar and 17.87 bar, respectively. The comparison of the settling time and steady-state error for both simulation and experiment were also the same. The settling time and steady-state error were 0.43 s and 0%, accordingly. Only, the overshoot of the experimental results was found higher than that of the simulation results. However, the overshoot of the experimental results was satisfied with the boundary condition, accounting for approximately 21.80% which is less than 25%. In conclusion, the validation test stated that the position control considering viscosity could be able to compensate for the viscous effects of hydraulic oils on the hydraulic system. This control law might also be able to control the movement of the hydraulic actuator. Because the movement of the actuator depends on the pressure supplied from the proportional valve. Therefore, it could be said that the position control considering viscosity could be feasible for the automatic planting depth control system of a rice transplanter that improve the rice transplanter planting accuracy with tilting of the planted seedlings. Ultimately, this control law could also be able to increase the comprehensive performance of the rice transplanter.