Bio-inspired Dual-auger Self-burrowing Robots in Granular Media

It has been found that certain biological organisms, such as Erodium seeds and Scincus scincus, are capable of effectively and efficiently burying themselves in soil. Biological Organisms employ various locomotion modes, including coiling and uncoiling motions, asymmetric body twisting, and undulating movements that generate motion waves. The coiling-uncoiling motion drives a seed awn to bury itself like a corkscrew, while sandfish skinks use undulatory swimming, which can be thought of as a 2D version of helical motion. Studying burrowing behavior aims to understand how animals navigate underground, whether in their natural burrows or underground habitats, and to implement this knowledge in solving geotechnical penetration problems. Underground horizontal burrowing is challenging due to overcoming the resistance of interaction forces of granular media to move forward. Inspired by the burrowing behavior of seed-awn and sandfish skink, a horizontal self-burrowing robot is developed. The robot is driven by two augers and stabilized by a fin structure. The robot's burrowing behavior is studied in a laboratory setting. It is found that rotation and propulsive motion along the axis of the auger's helical shape significantly reduce granular media's resistance against horizontal penetration by breaking kinematic symmetry or granular media boundary. Additional thrusting and dragging tests were performed to examine the propulsive and resistive forces and unify the observed burrowing behaviors. The tests revealed that the rotation of an auger not only reduces the resistive force and generates a propulsive force, which is influenced by the auger geometry, rotational speed, and direction. As a result, the burrowing behavior of the robot can be predicted using the geometry-rotation-force relations.Comment: Master's thesis, 62 pages, 40 figures, ProQues

Bio-inspired geotechnical engineering: principles, current work, opportunities and challenges

A broad diversity of biological organisms and systems interact with soil in ways that facilitate their growth and survival. These interactions are made possible by strategies that enable organisms to accomplish functions that can be analogous to those required in geotechnical engineering systems. Examples include anchorage in soft and weak ground, penetration into hard and stiff subsurface materials and movement in loose sand. Since the biological strategies have been ‘vetted’ by the process of natural selection, and the functions they accomplish are governed by the same physical laws in both the natural and engineered environments, they represent a unique source of principles and design ideas for addressing geotechnical challenges. Prior to implementation as engineering solutions, however, the differences in spatial and temporal scales and material properties between the biological environment and engineered system must be addressed. Current bio-inspired geotechnics research is addressing topics such as soil excavation and penetration, soil–structure interface shearing, load transfer between foundation and anchorage elements and soils, and mass and thermal transport, having gained inspiration from organisms such as worms, clams, ants, termites, fish, snakes and plant roots. This work highlights the potential benefits to both geotechnical engineering through new or improved solutions and biology through understanding of mechanisms as a result of cross-disciplinary interactions and collaborations

Bio-inspired geotechnical engineering: Principles, current work, opportunities and challenges

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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

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

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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 earthworm-like modular soft robot for locomotion in multi-terrain environments

Robotic locomotion in subterranean environments is still unsolved, and it requires innovative designs and strategies to overcome the challenges of burrowing and moving in unstructured conditions with high pressure and friction at depths of a few centimeters. Inspired by antagonistic muscle contractions and constant volume coelomic chambers observed in earthworms, we designed and developed a modular soft robot based on a peristaltic soft actuator (PSA). The PSA demonstrates two active configurations from a neutral state by switching the input source between positive and negative pressure. PSA generates a longitudinal force for axial penetration and a radial force for anchorage, through bidirectional deformation of the central bellows-like structure, which demonstrates its versatility and ease of control. The performance of PSA depends on the amount and type of fluid confined in an elastomer chamber, generating different forces and displacements. The assembled robot with five PSA modules enabled to perform peristaltic locomotion in different media. The role of friction was also investigated during experimental locomotion tests by attaching passive scales like earthworm setae to the ventral side of the robot. This study proposes a new method for developing a peristaltic earthworm-like soft robot and provides a better understanding of locomotion in different environments

A plant-inspired robot with soft differential bending capabilities

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Advances in soft grasping in agriculture

Agricultural robotics and automation are facing some challenges rooted in the high variability 9 of products, task complexity, crop quality requirement, and dense vegetation. Such a set of 10 challenges demands a more versatile and safe robotic system. Soft robotics is a young yet 11 promising field of research aimed to enhance these aspects of current rigid robots which 12 makes it a good candidate solution for that challenge. In general, it aimed to provide robots 13 and machines with adaptive locomotion (Ansari et al., 2015), safe and adaptive manipulation 14 (Arleo et al., 2020) and versatile grasping (Langowski et al., 2020). But in agriculture, soft 15 robots have been mainly used in harvesting tasks and more specifically in grasping. In this 16 chapter, we review a candidate group of soft grippers that were used for handling and 17 harvesting crops regarding agricultural challenges i.e. safety in handling and adaptability to 18 the high variation of crops. The review is aimed to show why and to what extent soft grippers 19 have been successful in handling agricultural tasks. The analysis carried out on the results 20 provides future directions for the systematic design of soft robots in agricultural tasks.Comment: Chapter 12 of the book entitled "Advances in agri-food robotics

Hybrid extendable linear actuators: design and applications

There are many types of different actuators in the field of robotics. For applications where a linear displacement is required, a linear extendable actuator would be the method of choice. The hybrid class of extendable actuators possesses unique features making it suitable for many applications where the soft and rigid types fall short. However, there has not been a clear designation and classification of extendable linear hybrid actuators in the literature. This paper addresses this matter and provides the first overview of the hybrid class of extendable actuators. The paper performs a categorization and characterization of this class of extendable linear actuators based on their method of operation as well as the inherent unique features separating them from the rest. The paper contains five sections, and three sub-sections pertaining to the different categories of Hybrid actuators, and their applications. New research in this field continues to add features to this class of actuators through improvements and added capabilities