Development and performance evaluation of an electric cabbage harvester with a precise cabbage pushing mechanism

Abstract

The manual method of harvesting cabbages is common in many Asian countries, which creates a lot of biomechanical problems among farmers. The existing commercial cabbage harvesters being bigger in size are not suitable for small landholdings. To address this, a three-wheeled walk-behind type electric cabbage harvester with a precise cabbage pushing mechanism was developed. It comprised a cutting unit, pushing unit, conveying unit, propelling unit, storage bin and handle. Based on the results obtained from laboratory tests, the cutting speed, forward speed and cutting position of cabbage stem from cabbage head was chosen as 590 rpm, 0.25 m/s and 0.1 cm. For pushing the cut cabbages precisely, a YOLOv8 custom cabbage detection model (mean average precision of 0.938) was developed and deployed in Nvidia Jetson Nano that could detect the cabbages and actuated a pusher via Arduino microcontroller and motor driver to push the cut cabbages to the conveyor belt. In the power supply unit of the harvester, 48 V 12 Ah, 12 V 7 Ah, and 24 V 18 Ah batteries were used for powering the motors for cutting, pushing, and propelling and conveying, respectively. The harvester was tested in a polyhouse for three Indian cabbage varieties. The maximum instantaneous power consumption (IPC) was measured as 948.53 W. Hand vibration and noise at operators’ ear level were 2.098 m/s2 and 78 dB(A), respectively, which confirmed its safety from an ergonomic perspective. The harvester achieved a maximum cutting efficiency of 77.5 % and a minimum damage rate of 7.5 % during polyhouse testing.