Plantoid: plant inspired robot for subsoil exploration and environmental monitoring

La Biorobotica è un nuovo approccio nella realizzazione di robot che unisce diverse discipline come Robotica e Scienze Naturali. Il concetto di Biorobotica è stato identificato per molti anni come ispirazione dal mondo animale. In questa tesi, questo paradigma è stato esteso per la prima volta al mondo vegetale. Le piante sono un organismo affascinante con inaspettate capacità. Sono organismi dinamici e altamente sensibili, in grado di esplorare il terreno alla ricerca di nutrienti e di valutare con precisione la loro situazione per una gestione ottimale delle risorse. L'obiettivo di questa tesi è di contribuire alla realizzazione di un robot ispirato alle piante, un plantoide. Il robot plantoide comprende sistemi di radici e rami e deve essere in grado di monitorare l'ambiente sia in aria sia nel sottosuolo. Questi robot ispirati alle piante saranno utilizzati per applicazioni specifiche, come il monitoraggio in situ di parametri chimici, la ricerca di acqua in agricoltura, l'ancoraggio e per la comprensione scientifica delle capacità e comportamenti delle piante stesse mediante la costruzione di modelli fisici. In questa tesi sono stati affrontati diversi aspetti di questa innovativa piattaforma robotica: prima di tutto, lo studio delle piante, le caratteristiche e le tecnologie che consentono di progettare e sviluppare il sistema robotico. Il sistema proposto può essere facilmente suddiviso in due sezioni principali, la parte aerea e la parte radicale (che sta nel sottosuolo). Per la parte che si trova nel sottosuolo, l'attività è stata incentrata sulla realizzazione di un sistema meccatronico miniaturizzato che imita il comportamento dell’apice radicale della pianta. Le piante mostrano una peculiare direzione crescita in risposta a stimoli esterni, come la luce (phototropism), la gravità (gravitropism), il tatto (thigmotropism) o il gradiente di umidità (hydrotropism). I tropismsi spesso interagiscono tra loro, e la crescita finale della pianta è influenzata da tali interazioni. Al fine di imitare le potenti prestazioni del sistema radicale delle piante, un nuovo attuatore è stato proposto. Questo attuatore è basato sul principio osmotico (attuatore osmotico) e, diversamente dagli attuatori allo stato dell’arte basati sul principio osmotico, è stato progettato in modo da avere una reazione reversibile. Questo attuatore permette di eseguire l'allungamento e il direzionamento dell’ apice radicale, generando elevate forze con un basso consumo di energia (con movimenti nella scala temporale della pianta). Studi teorici su questo attuatore mostrano interessanti prestazioni in termini di pressione di attuazione (superiore a 20 atm), con potenza nell'ordine di alcuni mW e con tempi di attuazione nell’ordine delle ore. L’apice radicale robotico è stato progettato per essere dotato di sensori (gravità e umidità) per imitare le capacità di analisi delle piante, e con l’attuatore osmotico per guidare la crescita nella direzione corretta. Un microcontrollore integrato controlla il comportamento e il direzionamento sulla base delle informazioni provenienti dai sensori. Riguardo la parte aerea, l'attività in questa tesi è stata incentrata sulla realizzazione di una sorta di modulo di monitoraggio ambientale, al fine di imitare l'elevata capacità sensoristica delle piante. Questa parte è stata progettata e realizzata in un modo più tradizionale, senza tentare di imitare completamente il comportamento delle piante, ma prendendo ispirazione dalle caratteristiche fondamentali (recupero dell’energia, ampia capacità di monitoraggio e comunicazione). Al fine di integrare una vasta quantità di sensori, è stata sviluppata un’innovativa interfaccia che garantisce il condizionamento di sensori, con capacità plug-and-play e basso consumo energetico. Diversi aspetti del plantoid non sono ancora stati affrontati e saranno parte dei lavori futuri. In particolare, il meccanismo di crescita delle radici (alcune possibili soluzioni sono state proposte e spiegate in questa tesi) e l'integrazione di sensori chimici nell’apice radicale.Biorobotics is a novel approach in the realization of robot that merges different disciplines as Robotic and Natural Science. The concept of biorobotics has been identified for many years as inspiration from the animal world. In this thesis this paradigm has been extended for the first time to the plant world. Plants are an amazing organism with unexpected capabilities. They are dynamic and highly sensitive organisms, actively and competitively foraging for limited resources both above and below ground, and they are also organisms which accurately compute their circumstances, use sophisticated cost–benefit analysis, and take defined actions to mitigate and control diverse environmental insults. The objective of this thesis is to contribute to the realization of a robot inspired to plants, a plantoid. The plantoid robot includes root and shoot systems and should be able to explore and monitoring the environment both in the air and underground. These plant-inspired robots will be used for specific applications, such as in situ monitoring analysis and chemical detections, water searching in agriculture, anchoring capabilities and for scientific understanding of the plant capabilities/behaviours themselves by building a physical models. The scientific work performed in this thesis addressed different aspects of this innovative robotic platform development: first of all, the study of the plants‟ characteristics and the enabling technologies in order to design and to develop the overall plantoid system. The proposed system can be easily sub-divided in two major sections, the aerial part and the subsoil part. About the subsoil part, the activity focused on the realization of a miniaturized mechatronic system that imitates the behaviour of the plant radical apex. Plants show a peculiar directional growth in response to external stimulations, such as light (phototropism), gravity (gravitropism), touch (thigmotropism) or water/humidity gradient (hydrotropism). Tropisms frequently interact between and among each other, and the final grown form of the plant is influenced by such interactions. In order to imitate the powerful performances of the plant root system, a novel actuator has been proposed. This actuator is based on the osmotic principle (osmotic actuator) and, differently by the state-of-the-art actuators based on the osmotic principle, it has been designed in order to have a reversible reaction. This actuator permits to perform the elongation and the typical steering capabilities of the root apex, generating high forces with low power consumption (in the time scale of the plant). Theoretical studies on this actuator show interesting performances in terms of actuation pressure (more than 20 atm) with power in the order of some mW and with actuation in the hours scale time. The robotic root apex was designed to be equipped with sensors (gravity and moisture) to imitate the plants sensing characteristics, and with the novel osmotic actuator to drive the growth in the correct direction. An embedded microcontroller implements the basic root behaviour on the basis of the information coming from the sensors. About the aerial part the activity in this thesis was focused on the realization of a sort of environmental monitoring module in order to imitate the high sensing capabilities of the plants. This part has been designed and realized in a more traditional way, without attempt to imitate completely the plant behaviour but taking inspiration from the fundamental characteristics (energy scavenging, wide sensing capabilities and communication). In order to integrate a wide amount of sensors an innovative interface board that guarantees the conditioning of the sensor, with plug-and-play capabilities and low power consumption, was developed. Several aspects of the plantoid system are not faced yet and they will be part of the future works. In particular, the growing mechanism of the roots (some possible solutions are proposed and explained in this thesis) and the integration of chemical sensors in the root apex

Octopus-Inspired Suction Cups with Embedded Strain Sensors for Object Recognition

The octopus has unique capacities are sources of inspiration in developing soft robotic-enabling technologies. Herein, soft, sensorized, suction cups inspired by the suckers of Octopus vulgaris are presented. The suction cups using direct casting are fabricated, so that materials with different mechanical properties can be combined to optimize sensing and grasping capabilities. The artificial suckers integrate four embedded strain sensors, individually characterized and placed in a 90 degrees configuration along the rim of the suction cup. Based on this arrangement, how well the sensory suction cup can detect 1) the direction and 2) the angle (from 30 degrees to 90 degrees) of a touched inclined surface and 3) the stiffness of a touched flat object (shore hardness between 0010 and D50) both in air and underwater is evaluated. Data processing on neural networks is based using a multilayer perceptron to perform regression on individual properties. The results show a mean absolute error of 0.98 for angles, 0.02 for directions, and 97.9% and 93.5% of accuracy for the material classification in air and underwater, respectively. In view of the results and scalability in manufacturing, the proposed artificial suckers would seem to be highly effective solutions for soft robotics, including blind exploration and object recognition

SIMBA: Tendon-Driven Modular Continuum Arm with Soft Reconfigurable Gripper

In this paper, we describe the conceptual design and implementation of the Soft Compliant Manipulator for Broad Applications (SIMBA) manipulator, which is designed and developed for participating in the RoboSoft Grand Challenge 2016. In our novel design, we have proposed (1) a modular continuum arm with independent actuation units for each module, to increase maintainability; (2) a soft reconfigurable hand, for a better adaptation of the fingers to objects of different shapes and size; (3) a moving base for increasing the workspace. We used a hybrid approach in designing and manufacturing by integrating soft and hard components, in both materials and actuation, providing high lateral stiffness in the arm through flat springs, soft joints in fingers for more compliancy and tendon-motor actuation mechanism providing flexibility but at the same time precision and speed. The SIMBA manipulator has demonstrated excellent grasping and manipulation capabilities by being able to grasp objects with different fragility, geometry, and size; and by lifting objects with up to 2 kg of weight it demonstrate also to be robust and reliable. The experimental results pointed out that our design and approach can lead to the realization of robots able to act in unknown and unstructured environments in synergy with humans, for a variety of applications where compliancy is fundamental, preserving robustness and safety

Multisource energy conversion in plants with soft epicuticular coatings

Living plants have recently been exploited for unusual tasks such as energy conversion and environmental sensing. Yet, using plants as small-scale autonomous energy sources is often impeded by multicable and -electrode installations on the plants. Moreover, insufficient power outputs for steadily driving even low-power electronics made a realization challenging. Here, we show that plants, by a modification of the leaf epicuticular region can be transformed into cable-free, fully plant-enabled integrated devices for multisource energy conversion. In detail, leaf contact electrification caused by wind-induced inter-leaf tangency is magnified by a transparent elastomeric coating on one of two interacting leaves. This enables converting wind energy into harvestable electricity. Further, the same plant is used as an unmatched Marconi-antenna for multi-band radio frequency (RF) energy conversion. This enables the use of the same plant as a complementary multi-energy system with augmented power output if both sources are used simultaneously. In combination, we observed over 1000% enhanced energy accumulation respective to single source harvesting in the specific application case and common plants like ivy could power a commercial sensing platform wirelessly transmitting environmental data. This shows that living plants have potential to autonomously supply application-oriented electronics while maintaining the positive environmental impact by their intrinsic sustainability and benefits such as O-2 production, CO2 fixation, self-repair, and many more

Soft Legged Wheel-Based Robot with Terrestrial Locomotion Abilities

In recent years robotics has been influenced by a new approach, soft-robotics, bringing the idea that safe interaction with user and more adaptation to the environment can be achieved by exploiting easily deformable materials and flexible components in the structure of robots. In 2016, the soft-robotics community has promoted a new robotics challenge, named RoboSoft Grand Challenge, with the aim of bringing together different opinions on the usefulness and applicability of softness and compliancy in robotics. In this paper we describe the design and implementation of a terrestrial robot based on two soft legged wheels. The tasks predefined by the challenge were set as targets in the robot design, which finally succeeded to accomplish all the tasks. The wheels of the robot can passively climb over stairs and adapt to slippery grounds using two soft legs embedded in their structure. The soft legs, fabricated by integration of soft and rigid materials and mounted on the circumference of a conventional wheel, succeed to enhance its functionality and easily adapt to unknown grounds. The robot has a semi stiff tail that helps in the stabilization and climbing of stairs. An active wheel is embedded at the extremity of the tail in order to increase the robot maneuverability in narrow environments. Moreover two parallelogram linkages let the robot to reconfigure and shrink its size allowing entering inside gates smaller than its initial dimensions

Toward Growing Robots: A Historical Evolution from Cellular to Plant-Inspired Robotics

This paper provides the very first definition of "growing robots": a category of robots that imitates biological growth by the incremental addition of material. Although this nomenclature is quite new, the concept of morphological evolution, which is behind growth, has been extensively addressed in engineering and robotics. In fact, the idea of reproducing processes that belong to living systems has always attracted scientists and engineers. The creation of systems that adapt reliably and effectively to the environment with their morphology and control would be beneficial for many different applications, including terrestrial and space exploration or the monitoring of disasters or dangerous environments. Different approaches have been proposed over the years for solving the morphological adaptation of artificial systems, e.g., self-assembly, self-reconfigurability, evolution of virtual creatures, plant inspiration. This work reviews the main milestones in relation to growing robots, starting from the original concept of a self-replicating automaton to the achievements obtained by plant inspiration, which provided an alternative solution to the challenges of creating robots with self-building capabilities. A selection of robots representative of growth functioning is also discussed, grouped by the natural element used as model: molecule, cell, or organism growth-inspired robots. Finally, the historical evolution of growing robots is outlined together with a discussion of the future challenges toward solutions that more faithfully can represent biological growth

an efficient soil penetration strategy for explorative robots inspired by plant root circumnutation movements

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Octopus‐Inspired Soft Arm with Suction Cups for Enhanced Grasping Tasks in Confined Environments

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