Effects of Temperatures and Viscosity of the Hydraulic Oils on the Proportional Valve for a Rice Transplanter Based on PID Control Algorithm

Abstract

This study was conducted to develop a proportional-integral-derivative (PID) control algorithm considering viscosity for the planting depth control system of a rice transplanter using various hydraulic oils at different temperatures and to evaluate the performance of the control algorithm, and compare the performance of the PID control algorithm without considering viscosity and considering viscosity. In this study, the simulation model of the planting depth control system and a PID control algorithm were developed based on the power flow of the rice transplanter (ERP60DS). The primary PID coefficients were determined using the Ziegler-Nichols (Z-N) second method. Routh’s stability criteria were applied to optimize the coefficients. The pole and double zero points of the PID controller were also applied to minimize the sustained oscillations of the responses. The performance of the PID control algorithm was evaluated for three ISO (The International Organization for Standardization) standard viscosity grade (VG) hydraulic oils (VG 32, 46, and 68). The response characteristics were analyzed using statistical method (ANOVA) and Duncan’s multiple range test (DMRT) at a significant level of 0.05 were performed through the statistical software SPSS. The results show that the control algorithm considering viscosity is able to control the pressure of the proportional valve, which is associated with the actuator displacement for various types of hydraulic oils. It was noticed that the maximum pressure was 15.405 bars at 0, 20, 40, 60, 80, and 100 °C for all of the hydraulic oils. The settling time and steady-state errors were 0.45 s at 100 °C for VG 32 and 0% for all of the conditions. The maximum overshoots were found to be 17.50% at 100 °C for VG 32. On the other hand, the PID control algorithm without considering viscosity could not control the planting depth, because the response was slow and did not satisfy the boundary conditions. The PID control algorithm considering viscosity could sufficiently compensate for the nonlinearity of the hydraulic system and was able to perform for any of temperature-dependent viscosity of the hydraulic oils. In addition, the rice transplanter requires a faster response for accurately controlling and maintaining the planting depth. Planting depth is highly associated with actuator displacement. Finally, this control algorithm considering viscosity could be helpful in minimizing the tilting of the seedlings planted using the rice transplanter. Ultimately, it would improve the transplanter performance.

Simulation of Design Factors of a Clutch Pack for Power-Shift Transmission for an Agricultural Tractor

“…Ding [ 50 ] stated that the damping ratio is a critical factor to make the hydraulic system unstable. The damping ratio is one of the main reasons for the overshoot [ 40 ]. The engagement time was 1.20 s at friction coefficient (0.09) and moment of inertia (2.0), which was the design criteria [ 38 ].…”

“…Also, the faster engagement time might be found at lower sliding friction coefficients but the shifting shock of the clutch pack is inversely proportional to the shifting time [ 51 ]. In case of friction coefficient (0.1) and moment of inertia (2.5), the maximum overshoot was found 25.93%, which exceeds the critical criteria (25%) [ 40 ]. The performance of the sliding velocity of the PST was shown in Table 4 .…”

“…When the viscosity of the oils decreases the flow rate increases. As a result, the pressure also increases meaning is that the temperature, flow rate, and pressure are inversely proportional to the viscosity of the hydraulic oils [ 40 ]. The experiment was conducted by three ISO standard hydraulic oils namely Kixx RD Z (VG 32, 46, 68).…”

“…The nobility of this study is the temperatures of the transmission oil were used instead of the generated heat by friction to determine the most affected factors and variables of hydraulic clutch pack. The main reason is the viscosity of the transmission oil depends on the temperature of the oil, which affects the supplied pressure of the proportional valve [ 40 , 41 ] that is used as the engagement pressure in the clutch. As the clutch engagement is performed by the hydraulic pressure, the performance of the PST depends on the viscosity of the transmission hydraulic oil [ 39 , 42 ].…”

Simulation of Fuel Consumption Based on Engine Load Level of a 95 kW Partial Power-Shift Transmission Tractor

“…Among them, approximately 50% of the tractor global market is in the Asia-Pacific region. In Korea, farmers aged over 65 years old account for 6.7% of the total in 2010; this is expected to be 11.3% in 2050 [7,8]. To compete with the largest tractor manufacturing companies in the global market, and to fulfill the consumers' demands, advanced technologies along with the highest facilities should be introduced.…”