Robotic Weeding – From Concept To Trials

Abstract

This paper reports on the use of robotic selective mechanical cultivation as an alternative method to herbicide control for managing weed species in zero-till cropping systems. Existing best-practice technology in weed spot spraying utilises infrared technology to detect and selectively spray weeds using herbicide at quantities significantly less than those used in normal blanket spray applications. This reduction in the herbicide de- creases operational costs and can be beneficial for the environment; however, the capital investment in the technology is substantial for farmers who wish to own and operate their equipment. While effective in reducing overall herbicide usage, the technology has done little to tackle the rapid evolution of herbicide resistant weed species. As a potential solution to this issue, our research over the past three years has been focused on the development of non-chemical methods of weed management utilising robot-enabled selective mechanical weeding. Used in conjunction with a robotic vehicle platform, a mechanical weeding array is capable of working throughout the day and night. The weeding tools have been designed to be removable and inter- changeable, allowing the use of tools especially designed for different weed species, weed densities, and soil types. The system developed consists of a one-degree-of-freedom array of weeding tines, actuated into the ground in time to remove individual weeds. Sensing of the weeds is enabled by a vision-based plant detection and classification system, while the timing for the implement actuation to hit the weed is determined as a function of the robot speed. The field trials reported in this paper demonstrate the potential of this robotic system for individualised weed treatment and multi-mode weed management methods. In particular, a trial of the mechanical weeding array in a fallow field over six weeks maintained the weed coverage in robot treated sections to be 1.5%, compared to 37% in the control areas not treated by the robot—a reduction in excess of 90% in weed coverage.