A Drone-Mounted Spring-Released Blade Launcher for Fall-Free Walnut Harvesting: Concept, Design Analysis and Feasibility Study

Abstract

Walnut harvesting in Jammu and Kashmir still depends on workers who climb tall, seedling-origin trees and strike the fruiting branches with long sticks. Hospital studies and news reports describe a recurring seasonal pattern of falls, spinal and head trauma, and deaths. This paper proposes a low-cost alternative: a detachable payload of about 200 g that can be fitted to any multirotor able to carry that mass. The payload holds up to ten lightweight, blade-tipped bolts, each held by a spring-loaded cradle and released one at a time by a servo motor commanded from the flight controller. A bolt severs the thin stalk on which a walnut cluster hangs, so the fruit drops to a collection sheet below. We describe the mechanical layout, the release electronics, the control-software flow, a first-order energy and mass budget, and a safety framework. We also discuss, candidly, the limits of the concept: the very large number of cuts a single tree requires, the effect of cutting on next-season fruiting wood, and the need for tests on real walnut stalks. The aim is to give the community a documented starting point for removing people from the crown of the tree.