Selection of dibble radius in automatic dibble type vegetable transplanter based on zero velocity condition in planting

Abstract

Mechanization in vegetable transplanting is the current need due to increase in the cultivable area of vegetables and subsequent non availability of agricultural labor. A mini tractor mounted automatic dibble type vegetable transplanter was designed for a plant to plant spacing of 60 cm. Transplanter consists of conveying, dibbling wheel and seedling ejection units. Dibbling wheel consist of four dibble cups, selected based on the ground clearance of under complete lift position of tractor. Size of dibble wheel (radius of swing) was selected based onnumber of dibble cupsand zero-velocity condition of dibble wheel. With four dibble cups and rear wheel diameter of 80 cm, the gear ratio selected between the rear wheel of tractor and dibble wheel was 0.95. Zero velocity condition of dibble was obtained for value λ ≥ 1. The shape of displacement plots depends on parametric function value λ. At all forward speeds of 0.72, 1.08, 1.44, 1.8 and 2.16 kmh-1 for dibble wheel radius of 10, 20 and 30 cm, the value of λ was less than 1. Increase in the radius beyond 38.5 cm, the value of λ was greater than equal to 1. The displacement plots observed trough shape for diameter less than 38.5 cm, while there observed a closed trochoid for the radius greater than 38.5 cm. Selection of radius above 38.5 cm of dibble wheel would have zero velocity condition of dibbling. At this radius of swing, dibbling would be vertical and plant would be less inclined after transplanting.