IEEE Robotics & Automation Magazine - September 2013 - 59

extract leaves from ToF data and infrared-intensity images.
The segmentation is fully automatic and is based on a novel
depth-segmentation algorithm, which can be applied to
sparse or noisy depth data and can cope with curved surfaces.
Another difference is that leaf models are fitted explicitly,
which allows us to localize grasping points.
The proposed system for automated plant probing is
related to vision-based robotic systems for fruit and vegetable
picking that have been proposed in the past for the automation
of harvesting tasks [6]. Often these systems first process and
segment the data to identify and represent the target. Based on
this representation, a robot action (e.g., cutting or grasping) is
executed. The image-processing task is often eased by fixing
the environment in a specific manner. For example, in a fruitdetachment system developed by Feng et al. [20] in 2008,
strawberries were grown on a uniformly colored surface to
simplify image segmentation. In our system, the environment
is less constrained, and the proposed computer-vision system
is thus more complex. Furthermore, a new robotic application,
i.e., the automatic sampling of leaves with a specific cutting
tool, was introduced and explored. To the authors' knowledge,
this is the first time that an active vision approach using ToF
depth has been applied to robotized plant measuring.
The method is based on several assumptions: 1) the
boundaries of leaves are visible in the infrared-intensity
image, 2) the leaf surfaces can be modeled by a basic quadratic function, 3) leaves of a specific plant type can be
described by a common 2-D contour, 4) leaves are large
enough to be analyzed with a ToF camera, and 5) the leaves
are static during probing. These assumptions may be violated
under certain conditions, but nevertheless we expect the
method to be applicable to many different types of plants,
given a controlled environment.
In conclusion, we tackled a quite complex task that
required the extraction of task-relevant plant parameters from
plant images using a multistage algorithm as well as the difficult problem of the actual execution of the robot motion
toward the plant. The automation of plant probing has a
potentially wide range of applications both in the agricultural
industry, in which certain (currently manual) tasks must be
repeatedly executed for multiple plants, and in botanic experimentation, e.g., for phenotyping, in which leaf sample discs
are commonly used to analyze plant development to determine the genetic factors that control growth.
Acknowledgments
This research was partially funded by EU GARNICS project
FP7-247947, project PAU+ (DPI2011-27510), and Grup consolidat SGR155. B. Dellen acknowledges support from the
Spanish Ministry of Science and Innovation through a
Ramon y Cajal program. S. Foix was supported by a Ph.D. fellowship from CSIC's JAE program.
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Guillem Alenyà, Institut de Robotica i Informatica Industrial
(CSIC-UPC), Barcelona, Spain. E-mail: galenya@iri.upc.edu.
Babette Dellen, Institut de Robotica i Informatica Industrial
(CSIC-UPC), Barcelona, Spain. E-mail: bdellen@iri.upc.edu.
Sergi Foix, Institut de Robotica i Informatica Industrial (CSICUPC), Barcelona, Spain. E-mail: sfoix@iri.upc.edu.
Carme Torras, Institut de Robotica i Informatica Industrial
(CSIC-UPC), Barcelona, Spain. E-mail: torras@iri.upc.edu.

september 2013

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