The project yielded numerous exploitable results of which many were made public. Main exploitable result is the sweet pepper harvester. Further exploitable results are: an autonomous mobile platform; a (patented) harvesting device (end-effector); post-harvest logistics for grasping & storing; fruit localization and maturity detection, deep learning tool for obstacle detection and avoidance; a ROS-framework for top-level robot control, motion planning and control for manipulator and platform, visual servoing and a user interface. Other supporting results are: 4 sweet pepper image databases; crop management strategies to obtain an open crop structure for robotic harvesting; test scenario’s; and an economic simulation tool.
In the existing double-stem row growing system 18% of ripe fruit were harvested, and the average cycle time to pick one fruit was 24 s. Here, SWEEPER performs about 4 times better than CROPS (6% and 106 s). A good progress; remaining bottlenecks are mainly speed, fruit clustering, occlusion of peppers by leafs and the fact that in a double-stem row cropping system only half of the fruit can be reached and harvested. Taking into account the optimized cropping system, it performed better. In a simulated optimal crop, for a single stem-row assumption, with most occluding leaves and fruit clusters pruned away beforehand, 61% of ripe fruit were harvested. This shows the potential that breeding or other ways to enhance fruit visibility and decrease fruit clustering will have for future robotic harvesting. This would require a whole systems approach in which crop breeding, a new single-stem row crop production system and enhancement of the robot performance form key elements. A fully autonomous robotic sweet pepper harvester, should be viable within 5-10 years.
In the meantime, the robot may be employed in an existing double-stem row cropping system to work as a co-assistant to manual pepper pickers. It requires a crop with lesser clustering and leaf occlusion, and further incremental enhancements for cycle-time (<10s), harvesting yield (~50%) and production losses (<1%). With small adaptations, results can also be used for other crops. In cucumber cropping systems, leaves are pruned continuously, which makes robotic harvesting even more easier than for sweet pepper.
SWEEPER focussed on a challenging field for robotic applications in high-tech greenhouses with very unstructured and variable environments. Robots will replace manual labour, at least partly, in those cases where labour and cost form a bottleneck. Introduction of robots will initiate new jobs for robotic operators and maintenance, as well as change pickers work by having a robot as co-worker. Growers will profit by being more independent from availability of skilled personnel. Machine building companies will profit by new businesses like selling or leasing robots. Results are applicable to other agricultural domains like f.i. open field fruit harvesting. Dissemination activities triggered world-wide a vast amount of requests for collaboration in research and business propositions for harvesting other crops, f.i. cucumber, tomato, grapes, apple, cardamom, banana, and coco palms. The consortium will exploit the results in future R&D and private-public projects.
