Objective  In order to solve the problem of the missed sowing and the uniform adjustment for sowing amount by the driven wheel existing in traditional mechanical rice direct seeder, and realize automatic and precise adjustment to the sowing amount of rice direct seeder.

Method  A traditional mechanical rice direct seeder, commonly used in the Southern Jiangsu area, was modified by incorporating an automatic seeding control system based on the PID speed control algorithm. During sowing, the working speed of implement was obtained by the designed speedometer. The theoretical rotational speed of sorting shaft was obtained according to sowing control strategy combining the set target sowing amount with the operational speed. The measured feedback speed of seeding axis closed the control loop of the DC motor using a PID speed regulation algorithm and an encoder, which could be adjusted on-line to achieve accurate seeding.

Result  The speed adjustment time of seeding motor without load was less than 0.63 s and the maximum overshoot was 8.21%. The longest time for the motors to be recharged was 0.32 s when a load of 12.5 N·m was applied to the device. For the target sowing amount, the maximum value of speed control error was less than 7.21%, speed error was less than 5.21%, and sowing amount error in field was less than 4.92%. When field speed of vehicle varied in step, the seeding speed responded in time and the vehicle had a higher seeding synchronization. The seeding adjustment performance was significantly improved using the automatic release meter compared with the conventional direct seeder.

Conclusion  The automation transformation of this system is easy, which focuses on improving the adjustment mechanism of sowing amount, improves the sowing performance of traditional seeder, and has a high adaptability to traditional rice direct seeder machine.