Design and experiment of the automatic leveling system for the seedbed precision leveler in rice seedling nursery

Efficient machinery is required for seedbed leveling in rice trellis seedling transplantation at present. In this study, a self-propelled machine was designed for the rice trellis seedbed precision leveling, in order to combine with the technical requirements of standardized seedling transplantation in the cold region. Electromechanical hydraulics was also integrated with the automatic leveling control system. The hydraulic oil pump and DC stepping motor were taken as the power end in the leveling system. The automatic control strategy was selected to drive the electromechanical roll angle leveling mechanism and hydraulic pitch angle compensation device in using attitude angle data during operation. The better level of the seedbed was obtained to carry out the leveling operation of the precision leveling machine. A Simulink module was used to simulate and then test the performance of roll angle leveling and pitch angle compensation. The results show that better response speed and accuracy were achieved in the roll angle leveling. The minimum action error was observed in the pitch angle compensation of the crushed soil scraper cylinder, the roll angle leveling time was 1.62 s, the overshooting amount was 1.5%, which fully meeting the requirements of stable control. The field test was conducted to verify the simulation. The automatic leveling control system was also embedded in the 1ZJP-2seedbed precision leveling machine. The test showed that the average value of attitude angle, root mean square error (RMSE), and higher stability were found in the operating machine equipped with the automatic leveling system, compared with the control group, the average value of the rolling angle of the operating machine equipped with theautomatic leveling system was −1.88°, the RMSE was 1.95°, and the average absolute error was 1.88°, the average value of the rolling angle of the operating machine in the control group was −2.37°, and the RMSE was 2.43°, and the average absolute error was 2.31°, the average RMSE of the action of pitch angle compensated soil crushing scraper cylinder was 0.145 cm. The performance of seedbed leveling was examined using an optical leveling instrument. The maximum average standard deviation of the seedbed elevation was reduced by 1.05 cm after the application of the automatic leveling control, compared with the pre-operation without leveling. The maximum average standard deviation of seedbed elevation without leveling was only 0.325 cm. The leveling operation was improved by about 229%-500%, compared with the normal operation. The quality of operations was improved by about 268%-384% than before.