Technological advancements towards developing a robotic pruner for apple trees: A review

Automation and robotics have been widely applied in many agricultural operations; however, the production operations of apple trees are usually performed manually. Pruning is one of the most labor-intensive operations, accounting for about 20% of the total labor costs. Robotic pruning is a potential long-term solution to deal with the issue of labor shortages and associated high costs. In recent years, researchers have advanced technologies that could lead to the development of a robotic pruning system. However, numerous challenges are involved for successful adoption of robotic pruning technologies. This review highlighted the technological progress in the core components of a robotic pruner including machine vision, manipulator, end-effector, path planning, and obstacle avoidance; the challenges associated with the existing technologies; and potential solutions to the development of an automated pruning system. The review covers both scientific/research and commercial technologies developed for robotic tree pruning. The available literature related to all technological components of a robotic pruning system was reviewed in detail, and useful information was synthesized for presenting in the paper. Finally, the paper scrutinizes the challenges and potential future opportunities for developing a robotic pruning system for a sustainable apple production system.