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Flora Robotica: Societies of Symbiotic Robot-Plant Bio-Hybrids as Social Architectural Artifacts

Periodic Reporting for period 3 - flora robotica (Flora Robotica: Societies of Symbiotic Robot-Plant Bio-Hybrids as Social Architectural Artifacts)

Reporting period: 2018-04-01 to 2019-03-31

Within the project flora robotica two essentials for our future life on earth are being merged: technology and nature. Following a simple yet radically new idea, our international team is envisioning and constructing a bio-hybrid society of robots and natural plants. This bio-hybrid society is able to reach collaborative goals by communicating, working, and growing together. flora robotica takes the first steps toward intelligent plants that can adaptively and sustainably grow or built our environment.

The world’s population is growing and a majority of people live in cities. We are losing contact to nature and don’t realize our fundamental dependency on natural plants for nutrition and oxygen. We should grow food on our houses and use plants to cool our buildings. flora robotica has developed fundamental tools to automatically grow plants into desired patterns, to keep certain spaces free of plants, and to steer the growth.

Objective 1 - Agency in mixed societies. We have worked to understand synergistic biological and technical systems. We have investigated a hybrid system consisting of plants, robots, and human beings that form synergistic relationships during a long-term developmental growth process. The plants and robots form a hybrid system and cooperate by sharing perceptions and by mutually providing support in decision-making.

Objective 2 - Smart artifacts. We have created smart architectural infrastructure as a cognitive being. The plant-robot system is applied as an autonomous, interactive developmental and cognitive system to create adapting architectural artifacts (walls, roofs) of various uses (sound-insulating, shading). We have created an adaptive growth process by exploiting different tropisms of the plants (phototropism, thigmotropism) along and against them. The perceptions of plants and robots are leveraged to adapt to interactions and behavioral patterns of human beings that are co-inhabitants of the same green infrastructure (offices, gardens).

Objective 3 - Structures as memory. Both plants and robots show self-organized growth with an embodied memory that integrates perceptions over time in shapes. The plant-robot system flora robotica forms a bio-hybrid ecology that we have investigated in terms of developmental plasticity and long-term controllability. We have applied decentralized/bio-inspired control, methods from swarm intelligence and from evolutionary robotics to implement a self-organizing, resilient adaptive system.
To establish a communication channel between robots and plants, we combined a variety of different sensors. We apply ready-to-use sensor technology, such as proximity sensing and vision, but we also develop new technology, such as electrophysiology, transpiration sensors, and sap flow sensors to interact with plants. We have designed and built highly specialized robotic devices with sensors and actuators that allow us to mix them with natural plants and to interact with plants. These robots are stationary but can be moved by human users to match growth rates of plants. Still, the control mechanisms of the robots are fast, and they are able to influence plants by high-intensity LEDs and spraying of growth inhibitors. We use blue light to attract plants via phototropism, that is, a plant’s innate tendency to grow towards visible light. Alternatively, we use a growth inhibitor to stop growth in undesired regions. In our experiments we have successfully tested the interplay of our robots with a variety of plant species, including the common bean, Wisteria, and Fallopia.

We have developed passive and active braided structures that serve as scaffold during the long-term developmental process. The braided scaffolds allow plants to grow through them, into them, along them and hence nicely implement the synergistic concept of this mixed society. We let plants interact with braided scaffolds that offer mechanical stimuli and trigger reactions by the plant, and have embedded electronics into material tests of braided scaffolds. We have investigated self-organized construction of braided scaffolds with mobile robots, in which the organizational structure of the filaments serves as an interpretable embodied memory of the robots' past behaviors.
flora robotica has designed, constructed, and investigated an autonomous system to steer and guide plant growth - a concept that has never been studied before. Our robotic nodes can be programmed by a user to grow a desired pattern or shape of plants without further human interaction. Another fundamental contribution is the integration of experiment protocols of plant science and robotics.

The plant-interaction mechanisms and the plant sensors, so-called phyto-sensors, that are investigated in flora robotica, have a considerable impact as they can be used in two ways. On the one hand, using them as standard sensors they give us knowledge about plant parameters. On the other hand, we can use the plant as a sensor for different external stimuli by using the phyto-sensors as interface to receive plant responses. We expect the emergence of a novel class of approaches to plant-treatment. In developing phyto-hybrid design, flora robotica representational methods have impacted the architectural community with a novel approach to the design and growth of artifacts involving self-organization by guaranteeing key attributes rather than specifying exhaustive descriptions of fine-scale details.
Besides the usual engineering objectives of maximizing functionality, performance and robustness, flora robotica offers architectural artifacts that combine functionality with sustainable organic growth and symbiotic sharing of functionality between plants and mechatronic technology.

The impact of flora robotica to plant science is due to the creation of new perspectives for plant biology. In flora robotica we focus on the regulation of plant growth in a different way than in foregoing agricultural or gardening practice. Actions of modular robots allow us to experiment with many localized stimulations of plants, which then influence the plant growth. An insight from this kind of plant stimulation is that the emerging interplay between local events and global effects in the organism’s development are of more importance than expected. Also new research perspectives appear in the reciprocal interactions and communication between plants and robots that require further investigation of mechanisms of plant-plant interactions, plant-animal interactions, and plant-environment interactions.

The long-term impact of flora robotica will be on how we grow plants in cities, in outdoor and indoor gardens, and on farmland. With automatic systems that grow plants in appropriate shapes and patterns, we will see more green infrastructure in our future megacities. Plants will help to cool our cities and in combination with practices of urban gardening and vertical gardening we will grow some of our food in immediate proximity to where it is consumed.
Growing plants on braided structures
Medium-scale experiment to showcase guidance of plants by robotic nodes
Final design of robotic node on braid with bean plants
Plant-robot interaction as illustration of electrophysiology
Large experiment on room scale
Overall concept sketch