Robotic Sensing and Stimuli Provision for Guided Plant Growth

Abstract

Robot systems are actively researched for manipulation of natural plants, typically restricted to agricultural automation activities such as harvest, irrigation, and mechanical weed control. Extending this research, we introduce here a novel methodology to manipulate the directional growth of plants via their natural mechanisms for signaling and hormone distribution. An effective methodology of robotic stimuli provision can open up possibilities for new experimentation with later developmental phases in plants, or for new biotechnology applications such as shaping plants for green walls. Interaction with plants presents several robotic challenges, including short-range sensing of small and variable plant organs, and the controlled actuation of plant responses that are impacted by the environment in addition to the provided stimuli. In order to steer plant growth, we develop a group of immobile robots with sensors to detect the proximity of growing tips, and with diodes to provide light stimuli that actuate phototropism. The robots are tested with the climbing common bean, Phaseolus vulgaris, in experiments having durations up to five weeks in a controlled environment. With robots sequentially emitting blue light-peak emission at wavelength 465 nm-plant growth is successfully steered through successive binary decisions along mechanical supports to reach target positions. Growth patterns are tested in a setup up to 180 cm in height, with plant stems grown up to roughly 250 cm in cumulative length over a period of approximately seven weeks. The robots coordinate themselves and operate fully autonomously. They detect approaching plant tips by infrared proximity sensors and communicate via radio to switch between blue light stimuli and dormant status, as required. Overall, the obtained results support the effectiveness of combining robot and plant experiment methodologies, for the study of potentially complex interactions between natural and engineered autonomous systems.

Constructing living buildings: a review of relevant technologies for a novel application of biohybrid robotics

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Figure 2.Two approaches to interaction between robots and natural organisms. ( a ) A robot interacts with plants by providing directional light stimuli, as seen in [134,135]. Image by authors.

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“…The models were used to control light stimuli and steer the plants to predetermined targets, adaptive targets, and around obstacles—in simulation and on real plants. This approach is extended to robots with distributed control, providing stimuli to guide the decisions of climbing plants, between several growth path options [134,135], see figure 2 a . Similar methods applied on a much larger scale could drive more complex construction processes with plants.…”

“…In this set-up, the plant has no mechanical scaffold, but the height to which it can support itself is not tall enough for building-sized growth. Steering with such stimuli is extended to distributed robotic control and larger sized growth [134,135]. In this set-up, the plants grow along a mechanical scaffold wall and the shape of their growth pattern is guided by stimuli.…”

“…The ability to quickly adapt to new situations, for instance, if a plant branches out, without losing the user-defined goals out of sight, for instance to grow in height, requires the robots’ controllers to handle a great variety of situations. Even in cases where the possible growth directions are intentionally restricted, as seen in figure 9, it has been shown that the task of robotically managing several plants simultaneously is quite complex [134,135]. The variety of goals, the expected flexibility, the complexity of the interactions in biohybrid systems, and in addition, the uncertainties and insufficient precision in perceiving and manipulating real-world environments would require the robots to learn [272].…”