In modern greenhouses, there is a high demand for automated labor. The availability of a skilled workforce that accepts repetitive tasks in harsh greenhouse climate conditions is decreasing rapidly. The resulting increase in labour costs and reduced capacity puts major pressure on the competitiveness of the greenhouse sector.
Team of scientists at Wageningen University (The Netherlands), Umeå University (Sweden) and Ben‐Gurion University of the Negev (Israel) has developed, tested and validated Sweeper, a robot for harvesting sweet pepper fruit in greenhouses.
The robotic system includes a six degrees of freedom industrial arm equipped with a specially designed end effector, RGB‐D camera, high‐end computer with graphics processing unit, programmable logic controllers, other electronic equipment, and a small container to store harvested fruit. All is mounted on a cart that autonomously drives on pipe rails and concrete floor in the end‐user environment. The overall operation of the harvesting robot is described along with details of the algorithms for fruit detection and localization, grasp poise estimation, and motion control.
The main contributions of this study are the integrated system design and its validation and extensive field testing in a commercial greenhouse for different varieties and growing conditions. A total of 262 fruits were involved in a 4‐week long testing period. The average cycle time to harvest a fruit was 24 s. Logistics took approximately 50% of this time (7.8 s for discharge of fruit and 4.7 s for platform movements). Laboratory experiments have proven that the cycle time can be reduced to 15 s by running the robot manipulator at a higher speed.
"The harvest success rates resulted 61% for the best fit crop conditions and 18% in current crop conditions - the scientists underline - This reveals the importance of finding the best fit crop conditions and crop varieties for successful robotic harvesting. The Sweeper robot is the first sweet pepper harvesting robot to demonstrate this kind of performance in a commercial greenhouse."
Source: Boaz Arad, Jos Balendonck, Ruud Barth, Ohad Ben‐Shahar, Yael Edan, Thomas Hellström, Jochen Hemming, Polina Kurtser, Ola Ringdahl, Toon Tielen, Bart van Tuijl, 'Development of a sweet pepper harvesting robot', 2020, Journal of Field Robotics