How to maintain the continuity and uniformity of transplanting when the rice transplanter turns at a bend or at the end of the field

In rice cultivation, straight-line operation is relatively straightforward for rice transplanters. However, when navigating curves at the edge of a field or on irregularly shaped fields, ensuring consistent and uniform planting becomes a crucial skill. When turning, the different speeds of the inner and outer wheels of traditional rice transplanters cause the movement trajectory of the transplanting arm to vary at different locations. This can lead to unstable planting, missed plantings, and uneven seedling spacing, seriously impacting work quality and final yield.

Precise Synchronization: Differential Mechanism and Independent Drive

When turning, the speeds of the inner and outer drive wheels of a rice transplanter must differ. To address this, modern rice transplanters commonly use a differential mechanism. This mechanism, similar to the principle of a car's differential, allows the left and right drive wheels to rotate at different speeds, thus achieving smooth steering. However, relying solely on a differential mechanism is insufficient to solve the transplanting problem, as the transplanter's planting mechanism is driven by the rotation of the travel wheels.

When turning, the outer travel wheels rotate faster, while the inner travel wheels rotate slower. If the transplanting mechanism remains simply mechanically connected to the travel wheels, the outer transplanting arms will plant more frequently than the inner ones, resulting in smaller plant spacing on the outer sides and wider plant spacing on the inner sides, creating a noticeable "fan-shaped" unevenness.

To eliminate this unevenness, some high-end transplanters use independently driven transplanting mechanisms. This means the transplanting mechanism is no longer directly driven by the travel wheels, but instead controlled by an independent hydraulic motor or electric motor. Sensors monitor the transplanter's steering angle and travel speed in real time, allowing the control system to precisely adjust the drive frequency of each transplanting arm. When the machine turns right, the system slows down the left transplanting arm and speeds up the right arm to compensate for the speed difference between the inner and outer rows, ensuring consistent planting spacing across all rows.

Intelligent Compensation: Linking Steering Angle with Transplanting Arms

In addition to differential speed and independent drive, a steering angle sensor is key to achieving precise planting during turns. Installed on the steering mechanism, this sensor transmits steering angle information in real time to the central control unit.

Based on the steering angle, the control unit calculates the required compensation ratio for the inner and outer transplanting arms. For example, when the steering angle is large, the difference in linear speed between the inner and outer rows increases, and the control system will increase compensation accordingly. This closed-loop control ensures that the transplanting arm operates at the optimal frequency regardless of the turning radius.

In addition, some advanced rice transplanters are equipped with automatic steering systems that utilize GPS or Beidou navigation systems. These systems not only guide the transplanter along a pre-set curved path but also provide real-time position and steering information to the transplanting control system. Before entering the curve, the system pre-calculates the optimal planting frequency compensation plan, ensuring a smooth and seamless turn with virtually no trace of human intervention. This intelligent linkage achieves a quantum leap from "stable" to "accurate" planting.

Headland Management: Improving Efficiency and Reducing Waste

Headland turning is another critical step in rice transplanting. At the headland, the machine must complete a U-turn and realign with the next row. Traditionally, this interrupts the transplanting process. However, to improve efficiency and reduce missed plantings, modern transplanters have introduced automatic headland lifting and planting interruption systems.

When the machine reaches a preset headland position, the operator or the automatic control system triggers the lift function. The planting mechanism and pontoon automatically raise and clear the paddy field surface. Simultaneously, the planting mechanism's drive automatically stops to prevent empty plantings or planting onto the ridge. After turning around and entering the next row, the system automatically lowers the planting mechanism based on its positioning and resumes planting.

This automatic headland management function not only significantly reduces operator workload but, more importantly, ensures seamless transitions between different working rows. Using precise position sensors and limit switches, the system ensures that planting starts and stops at the correct points, eliminating gaps or overlaps that are common in the headland. This improves overall plant uniformity and efficiency, maximizing the use of valuable seedling resources.