Technical Comittee on: Agricultural Robotics and Automation
Program May, 2013

Manoj Karkee, Washington State University, USA: Identification of Pruning Branches in Tall Spindle Apple Trees for Automated Pruning

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Pruning is a labor intensive operation that constitutes a significant component of total apple production cost. Automation and mechanization are important and underutilized technologies with a potential to reduce labor dependency for pruning. As growers adopt simpler, narrower, more accessible and productive (SNAP) tree architectures such as the Tall Spindle fruiting wall system, new opportunities emerge for automated pruning.

This work focuses on identification of pruning branches on apple trees in a Tall Spindle architecture. A time-of-flight-of-light-based three dimensional (ToF 3D) camera is used to obtain 3D information and construct 3D skeletons of apple trees in a commercial orchard. Pruning branches are identified in the reconstructed trees using a simplified two-step pruning rule: (i) maintain specified branch spacing and (ii) maintain specified branch length.

Tests are conducted to identify branches that need to be pruned. Performance of the algorithm is compared against human pruning. The pruning branch identification of the algorithm is closest to the pruning branch identification of a worker with 10 years of experience. The algorithm suggests a removal of 17% of branches on average whereas the worker removes 16% of branches on average. These results show promise for automated pruning of tall spindle apple trees in the future.



Dr. Manoj Karkee is an Assistant Professor in the Biological Systems Engineering Department and Center for Precision and Automated Agricultural Systems (CPAAS) at Washington State University. Dr. Karkee was born and raised in Nepal, some 400 km east of Kathmandu. After completing high school, he moved to Kathmandu for his undergraduate degree. He received his bachelor’s degree in Computer Engineering in 2002 from Tribhuvan University, and then moved to Asian Institute of Technology, Thailand where he earned his Master’s Degree in Remote Sensing and GIS. In 2009, Dr. Karkee received his PhD in Agricultural Engineering and Human Computer Interaction from Iowa State University. Dr. Karkee works in the areas of agricultural automation and mechanization, with particular emphasis on machine vision systems for robotics and automation of production agriculture. He has been working on various research projects in this area, including apple tree pruning, apple crop load estimation, apple and cherry harvesting, water and nutrient stress monitoring, and solid set canopy delivery. In his personal life, Dr. Karkee enjoys spending time with his family, singing Nepali songs, reading and writing literature and playing sports including Volleyball and Badminton.


Last modified: apr. 2014 by Eldert van Henten and Sam Blaauw