Papers by Barbara Mazzolai
Energy consumption of the root-like device prototype in EFT and NoEFT penetration trials
Investigation of Tip Extrusion as an Additive Manufacturing Strategy for Growing Robots
This paper presents a new design for material extrusion as embeddable additive manufacturing tech... more This paper presents a new design for material extrusion as embeddable additive manufacturing technology for growing robots inspired by plant roots. The conceptual design is proposed and based on the deposition of thermoplastic material a complete layer at a time. To guide the design of the system, we first studied the thermal properties through approximated models considering PLA (poly-lactic acid) as feeding material. The final shape and constituent materials are then accordingly selected. We obtained a simple design that allows miniaturization and a fast assembly of the system, and we demonstrate the feasibility of the design by testing the assembled system. We also show the accuracy of our thermal prediction by comparing the thermal distribution obtained from FEM simulations with experimental data, obtaining a maximal error of ~8 °C. Preliminary experimental growth results are encouraging regarding the potentialities of this approach that can potentially achieve 0.15 \( \div \) 0...
Advanced Intelligent Systems, 2021
Unlike conventional robots, soft robots are mostly inspired by biological systems and try to imit... more Unlike conventional robots, soft robots are mostly inspired by biological systems and try to imitate the intrinsic softness, flexibility, and adaptability that conventional robots cannot achieve without direct control of motor function. [1] In conventional robots, the components, such as motors, sensors, rigid links, and controllers, are usually easily stacked. Soft robotics, instead, imitates biological structures in which sensing, control, and actuation are fully integrated and distributed in a soft body. [2-4] In addition, a soft and flexible body enables the robot to be lighter, adaptable, and operatable in humaninhabited environments, where both robustness and reliability ensure compliance and safety. [5,6] This approach to robotics has created a series of novel soft mobile platforms, manipulators, and other structures that perform increasingly complex tasks, such as locomotion on uneven terrain, manipulating objects of known and unknown shapes, wearable robotics-all benefitting from the intrinsic property of a soft robotic system. [7-10] There are several actuation principles behind these goals, which span from pressure-driven [11-13] and tendon-driven [14,15] to various stimulus responses (e.g., humidity, temperature, light). [16-19] Of these, pneumatic-driven, soft, muscle-like actuators exploit the effects of multiple mechanical deformations to generate controlled motion. [20-22] To better understand the actuation of soft deformations and the related robotic behavior, embedded sensing plays a major role in controlling the current configuration and enabling a live interaction with the environment. An inherently compliant system thus needs to be able to sense whether the deformation is self-induced through actuation or a consequence of an external stimulus. Using such information, a soft actuator can detect changes in the environment and adapt to them by modifying its configuration, [23] behavior, [24] and the force applied. [25] However, in most cases, this information is provided by external sensing units, such as cameras or motion trackers. [26] Some elastomeric-based actuators have also demonstrated both exteroception and proprioception through embedded strain and pressure sensors, [27,28] enabling them to sense and respond to external forces. [29-33]
Soft Robotics, 2019
This article presents strategies for the passive path and morphological adaptation of a plant-ins... more This article presents strategies for the passive path and morphological adaptation of a plant-inspired growing robot that can build its own body by an additive manufacturing process. By exploiting the soft state of the thermoplastic material used by the robot to build its structure, we analyzed the ability of the robot to change its direction of growth without the need for specific cognition and control processes. Obstacle avoidance is computed by the mechanics from the body-environment interaction. The robot can passively adapt its body to flat obstacles with an inclination of up to 50°with resulting reaction forces of up to *10 N. The robot also successfully performs penetration and body adaptation (with 30°obstacle inclination) in artificial soil and in a rough unstructured environment. This approach is founded on observing plant roots and how they move and passively adapt to obstacles in soil before they actively respond followed by cell division-based growth.
Advanced Intelligent Systems, 2019
Octopuses have impressive manipulation capabilities empowered by the intrinsic adaptation of thei... more Octopuses have impressive manipulation capabilities empowered by the intrinsic adaptation of their soft arms combined with distributed suckers. Drawing inspiration from the arm morphology and abilities of the octopus, this paper presents the integrated design of a conical soft robotic arm endowed with suction cups. The
Actuators, 2019
We present the design, manufacturing, and characterization of a soft textile-based clutch (TBC) t... more We present the design, manufacturing, and characterization of a soft textile-based clutch (TBC) that uses vacuum stimulation to switch between locking and unlocking its linear displacement. The vacuum locks the relative sliding motion between two elaborated textile webbings with an elastic silicone rubber bag. Various fabrication techniques, such as silicone casting on textiles and melt embossing for direct fabrication of miniature patterns on textile and sewing, were used to develop three groups of TBC samples based on friction and interlocking principles. Their performance was compared in a blocking configuration. The clutch with an interlocking mechanism presented the highest withstanding force (150 N) compared to that (54 N) recorded for the friction-based clutch. The simple and compact structure of the proposed clutch, together with the intrinsic adaptability of fabric with other clothing and soft materials, make it an appropriate solution for applications in soft wearable robo...
Biomimetics, 2018
We present the basic module of a modular continuum arm (soft compliant manipulator for broad appl... more We present the basic module of a modular continuum arm (soft compliant manipulator for broad applications (SIMBA)). SIMBA is a robotic arm with a hybrid structure, namely a combination of rigid and soft components, which makes the arm highly versatile, dexterous, and robust. These key features are due to the design of its basic module, which is characterized by a three-dimensional workspace with a constant radius around its rotation axis, large and highly repeatable bending, complete rotation, and passive stiffness. We present an extensive analysis and characterization of the basic module of the SIMBA arm in terms of design, fabrication, kinematic model, stiffness, and bending behavior. All the theoretical models presented were validated with empirical results. Our findings show a positional typical error of less than ≈6% in module diameter (highly repeatable) with a passive stiffness of 0.8 N/mm (≈1 kg load). Our aim is to demonstrate that this kind of robotic element can be exploited as an elementary module of a more complex structure, which can be used in any application requiring high directional stiffness but without the need for an active stiffness mechanism, as is the case in daily activities (e.g., door opening, water pouring, obstacle avoidance, and manipulation tasks).
Advanced Functional Materials, 2018
Progress towards green and autonomous energy sources includes harnessing living systems and biolo... more Progress towards green and autonomous energy sources includes harnessing living systems and biological tissue. It is recently discovered that the cuticle-cellular tissue bilayer in higher plant leaves functions as an integrated triboelectric generator conductor couple capable of converting mechanical stimuli into electricity. Here, it is investigated for the first time, in detail how charge generation at the living plant leaf occurs, and it is shown how whole plants could be used in plant-hybrid wind-energy harvesting systems. The charge accumulation and compensation in and ex vivo on Rhododendron leaves by Kelvin force microscopy is verified, revealing that charges are induced and transported in living plant tissue whereas charges remain unbalanced and trapped on dead leaves of the same species. A distinct sensing functionality and opportunity to upscale power output is given as electrical signals are species, touch-material, and dose-dependent and scale with frequency, impact force, and area. It is shown that also purely natural mechanical stimuli by wind or self-touching of leaves are converted into electrical signals by a triboelectric mechanism. The entirely plant-enabled and autonomous energy conversion can be used to directly drive light emitting diodes, charge a capacitor, and harvest wind-energy with promise for new energy sources based on the Plant Kingdom.
Soft Robotics, 2017
In this article, we present a novel class of robots that are able to move by growing and building... more In this article, we present a novel class of robots that are able to move by growing and building their own structure. In particular, taking inspiration by the growing abilities of plant roots, we designed and developed a plant root-like robot that creates its body through an additive manufacturing process. Each robotic root includes a tubular body, a growing head, and a sensorized tip that commands the robot behaviors. The growing head is a customized threedimensional (3D) printer-like system that builds the tubular body of the root in the format of circular layers by fusing and depositing a thermoplastic material (i.e., polylactic acid [PLA] filament) at the tip level, thus obtaining movement by growing. A differential deposition of the material can create an asymmetry that results in curvature of the built structure, providing the possibility of root bending to follow or escape from a stimulus or to reach a desired point in space. Taking advantage of these characteristics, the robotic roots are able to move inside a medium by growing their body. In this article, we describe the design of the growing robot together with the modeling of the deposition process and the description of the implemented growing movement strategy. Experiments were performed in air and in an artificial medium to verify the functionalities and to evaluate the robot performance. The results showed that the robotic root, with a diameter of 50 mm, grows with a speed of up to 4 mm/min, overcoming medium pressure of up to 37 kPa (i.e., it is able to lift up to 6 kg) and bending with a minimum radius of 100 mm.
2012 4th IEEE RAS & EMBS International Conference on Biomedical Robotics and Biomechatronics (BioRob), 2012
In this paper, we present an adhesion mechanism that can be used for underwater climbing robots a... more In this paper, we present an adhesion mechanism that can be used for underwater climbing robots and manipulators. The proposed design is inspired from tube feet of sea urchins, which use a combination of suction by extra soft sucker pads with assist of chemical adhesive materials. An experimental analysis of the bioinspired adhesive suckers (in single and array fashion) was performed and the obtained results show a repeatable increase in generated forces by single soft suckers, as compared with commercial sucker clamps. The main advantage of this sucker is its capability of adapting to the rough surfaces and to perform attachment. The other features of the sucker are its simple design, ease of manufacturing, and the capability of miniaturization for miniature robotic applications. I. INTRODUCTION NDERWATER biological adhesion mechanisms are strong sources of inspiration for robotic researchers for the development of innovative underwater robots and manipulators. When endowing robots with adhesion capability, they can be able to climb surfaces, grasp and manipulate objects, and in swimming robots that need to stay in a fixed position for a special task, adhesion helps them to withstand the underwater hydrodynamic forces. Several investigations were addressed in order to understand underwater adhesion principles and also, in order to apply them in robotics. Anatomical studies and 3D reconstruction of octopus suckers [2] were recently addressed in order to understand their adhesion strategy, while simulation of octopus suckers were reported [1]. Moreover, a climbing robot based on sucker principle by using SMA actuators was reported [3]. Bellows-type sucker was also studied for underwater application based on bio-inspired principles [4]. There are different techniques used by marine animals. The well-known techniques can be classified in three groups. First, suction based adhesions like octopus[5] or leech [6]; second, adhesion based on chemical adhesive, like mussels[7]; and, third combination of chemical adhesives and suction like limpets [8],[9]. Sea urchins (Fig. 1, left) are a wonderful group of marine animals, that can, temporarily, attach to a wide range of substrates, move, and manipulate food, by using numbers of Manuscript
Supplementary Information
Scientific reports, Jan 5, 2015
An emerging challenge in soft robotics research is to reveal mechanical solicitations in a soft b... more An emerging challenge in soft robotics research is to reveal mechanical solicitations in a soft body. Nature provides amazing clues to develop unconventional components that are capable of compliant interactions with the environment and living beings, avoiding mechanical and algorithmic complexity of robotic design. We inspire from plant-root mechanoperception and develop a strategy able to reveal bending and applied force in a soft body with only two sensing elements of the same kind, and a null computational effort. The stretching processes that lead to opposite tissue deformations on the two sides of the root wall are emulated with two tactile sensing elements, made of soft and stretchable materials, which conform to reversible changes in the shape of the body they are built in and follow its deformations. Comparing the two sensory responses, we can discriminate the concave and the convex side of the bent body. Hence, we propose a new strategy to reveal in a soft body the maximum...
Plant Root Strategies for Robotic Soil Penetration
Lecture Notes in Computer Science, 2013
ABSTRACT Soil penetration strategies of plant roots can represent an interesting source of inspir... more ABSTRACT Soil penetration strategies of plant roots can represent an interesting source of inspiration for designing explorer robots. In this work we present a selection of these strategies whose performances were discussed and evaluated by means of engineering mock-ups and dedicated experiments in granular substrates. The obtained results demonstrated that root elongation from the tip reduces the forces needed for soil penetration up to 50%; tip morphology and anchorage resulted to strongly influence penetration performances.
PLoS ONE, 2014
Moving in an unstructured environment such as soil requires approaches that are constrained by th... more Moving in an unstructured environment such as soil requires approaches that are constrained by the physics of this complex medium and can ensure energy efficiency and minimize friction while exploring and searching. Among living organisms, plants are the most efficient at soil exploration, and their roots show remarkable abilities that can be exploited in artificial systems. Energy efficiency and friction reduction are assured by a growth process wherein new cells are added at the root apex by mitosis while mature cells of the root remain stationary and in contact with the soil. We propose a new concept of root-like growing robots that is inspired by these plant root features. The device penetrates soil and develops its own structure using an additive layering technique: each layer of new material is deposited adjacent to the tip of the device. This deposition produces both a motive force at the tip and a hollow tubular structure that extends to the surface of the soil and is strongly anchored to the soil. The addition of material at the tip area facilitates soil penetration by omitting peripheral friction and thus decreasing the energy consumption down to 70% comparing with penetration by pushing into the soil from the base of the penetration system. The tubular structure provides a path for delivering materials and energy to the tip of the system and for collecting information for exploratory tasks.
Hierarchical multiple peeling simulations
ABSTRACT The phenomenon of the exceptional dry adhesion achieved by some natural biological mater... more ABSTRACT The phenomenon of the exceptional dry adhesion achieved by some natural biological materials has been widely investigated in recent years. In particular, the analysis of the terminal elements of gecko pads and their specific structure and topology has led to the development of bioinspired synthetic fibrillar adhesives, including mushroom-shaped tips. To model the expected adhesion and detachment behaviour of multiple contacts, only recently the last author has derived a theory of multiple peeling, extending the pioneering energy-based single peeling theory of Kendall, including large deformations and pre-stretching. In this contribution, we study the problem of the adhesion of single and multiple contacts using finite element analysis, with the aim of studying complex peeling geometries. Both non-hierarchical tape-like and hierarchical geometries are considered, and the adhesive properties are compared, showing a marked improvement in the latter case. Results are promising and the numerical approach can be exploited in future attempts to determine optimal configurations and improve the adhesion of artificial bioinspired structures.
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Papers by Barbara Mazzolai