Proprioceptive sensing plays a crucial role in robotics, enabling closed-loop control approaches that are essential for autonomous applications. In Soft Robotics, the development and integration of sensors is even more challenging due to the compliant nature of soft bodies. Moreover, underwater environments pose additional difficulties, as sensors require to be properly embedded and sealed into the soft body of the robot. The novelty of this work lies in benchmarking different sensing technologies on a continuum soft robot to systematically assess their suitability as effective sensing approaches, both in air and underwater environments. This work presents two proprioceptive sensors (FBG optical sensor and IMUs system) embedded in an octopus-inspired robotic arm and are then tested using our proposed experimental protocol. The results underscore the system’s ability to reliably and repeatably capture data and provide a valuable guideline for the community to adopt in order to test novel sensing modalities in soft robotics. These developments are pivotal in advancing the deployment of soft robotic systems in both above- and underwater settings, facilitating tasks ranging from infrastructure inspection to marine life studies.

Plant cells expand and elongate. Their cumulative actuation defines organ morphing. Inspired by this modular transformability, this study proposes a modular concept for growing robots that will be able to grow by adding at their tip Transformable Modules (TMs). We provide a two-module implementation to evaluate the concept viability. We designed and characterized Shape-Retention Bellows (SRBs) that constitute the TM and are used to maintain the shape once the extension force is relaxed. We demonstrate module radial expansion and axial elongation in a straight and bent configuration (up to ~4°). This is the first concept of growing robots to enact the robot's modularity and transformability for future deployment in distributed growing systems capable of acting in various scenarios.

Plants thrive in virtually all natural and human-adapted environments and are becoming popular models for developing robotics systems because of their strategies of morphological and behavioral adaptation. Such adaptation and high plasticity offer new approaches for designing, modeling, and controlling artificial systems acting in unstructured scenarios. At the same time, the development of artifacts based on their working principles reveals how plants promote innovative approaches for preservation and management plans and opens new applications for engineering-driven plant science. Environmentally mediated growth patterns (e.g., tropisms) are clear examples of adaptive behaviors displayed through morphological phenotyping. Plants also create networks with other plants through subterranean roots-fungi symbiosis and use these networks to exchange resources or warning signals. This article discusses the functional behaviors of plants and shows the close similarities with a perceptron-like model that could act as a behavior-based control model in plants. We begin by analyzing communication rules and growth behaviors of plants; we then show how we translated plant behaviors into algorithmic solutions for bioinspired robot controllers; and finally, we discuss how those solutions can be extended to embrace original approaches to networking and robotics control architectures.

Pneumatic actuators have gained huge popularity in the field of soft robotics. A class of this kind of devices exploits inflatable thin membranes which generate a desired displacement upon inflation, but often without providing sufficient force/torque to perform their task. In this paper, we propose a novel actuator combining a membrane and a rigid foldable structure. Experimental tests show that such INFlatable ORigami Actuator (INFORA) is characterized by relatively high stiffness compared to other actuators of the same class. We provide a mathematical model to be used for design purposes and we describe the fabrication process. In addition, we show how the INFORA can be used to build a tendril-like structure capable of performing grasping tasks.

Nowadays, robots can navigate complex and dynamic environments such as air, water, and different terrain. However, moving into the underground, and especially into the soil, is still a challenge. Soil is a complex environment, and its exploration and monitoring is a crucial aspect in different engineering fields. Although some robotic solutions for mapping the soil are available, none of them can navigate into it. In this work, we propose a new solution for dynamic obstacles detection by embedding a 6-axis force torque sensor into a plant-inspired robot for soil exploration. We measured the forces acting on the apical part of the robot while it penetrates the soil by growing. We tested the system in different configurations, and at different depths. Results show that it is possible to identify the relative position of the obstacle before touching it with the robot. By using the proposed method as control feedback it is possible to move toward the development of novel robotic systems for navigating in complex and dynamic environments, such as the soil.

BACKGROUND: In most mammals, a vast array of genes coding for chemosensory receptors mediates olfaction. Odorant receptor (OR) genes generally constitute the largest multifamily (> 1100 intact members in the mouse). From the whole pool, each olfactory neuron expresses a single OR allele following poorly characterized mechanisms termed OR gene choice. OR genes are found in genomic aggregations known as clusters. Nearby enhancers, named elements, are crucial regulators of OR gene choice. Despite their importance, searching for new elements is burdensome. Other chemosensory receptor genes responsible for smell adhere to expression modalities resembling OR gene choice, and are arranged in genomic clusters - often with chromosomal linkage to OR genes. Still, no elements are known for them. RESULTS: Here we present an inexpensive framework aimed at predicting elements. We redefine cluster identity by focusing on multiple receptor gene families at once, and exemplify thirty - not necessarily OR-exclusive - novel candidate enhancers. CONCLUSIONS: The pipeline we introduce could guide future in vivo work aimed at discovering/validating new elements. In addition, our study provides an updated and comprehensive classification of all genomic loci responsible for the transduction of olfactory signals in mammals.

This paper presents a new material deposition strategy for developing a growing robot capable of building its own body. The growing robot is inspired by plant growth and is based on a 3D printer-like mechanism. The plotting of a filament near the tip allows the forward movement of the robot and results in building a tubular body. A material deposition process is introduced to perform a straight continuous growth as well as a turning behavior in order to permit the navigation of the robot in the environment. Bending is achieved by controlling the filament height in each position of the plotting, lowering or increasing plotting velocity with a position PID control algorithm. We demonstrate that the continuous deposition of the filament allows to obtain homogeneous and robust structures, with a significant improvement of the robot's performance compared to our previous version of the system (i.e., more than 100 N pulling force and 200 N shear force). The current version of the robot can sustain its weight, move efficiently by growing in the environment - both air and soil - and penetrate hard medium (up to 60kPa).

In this paper, we present a study on peculiar plant root movements, named circumnutations, adopted by plants as an efficient strategy to penetrate the soil and implemented in robotic roots to improve their performance in exploration tasks. The robotic root is able to bend and interact with soil owing to a soft actuation mechanism based on the translation of rotary to linear motion by means of helical compression springs. The robotic root integrates a stimulus-oriented behavior combined with circumnutation movements, which leads to an extraordinarily large reduction (more than 80 times) of the force needed for penetration in artificial soil (sawdust) while performing circumnutations with respect to a straightforward movement.

Micro-technologies based on wirelessly powered and manoeuvred submillimeter device, i.e.,microrobots, are attracting growing attention. Their application in lab-on-a-chip systems, such as micromanipulation and in vitro cell sorting, is expected to steeply increase. However, the actuation, powering and control of microrobots are challenges that still need concrete solutions. Magnetic fields generally enable wireless navigation of microrobots, but proper control architectures and magnetic navigation systems are needed, depending on the specific task and on the level of interaction required to the user. Here we present a magnetic navigation platform intended for lab-on-a-chip applications and we address its usability with different levels of human involvement by using two control architectures: teleoperated and autonomous. We perform an experimental analysis to demonstrate that both architectures, enrolling different levels of interaction by the user, lead to reliable execution of the microrobotic task. First, we validate the open-loop response of the microrobotic system, and second, we evaluate the performance of the system by testing both control architectures with a standard mobility task. The results show that users can teleoperate the microrobot with 100% success rate, in 14.4±1.9s with a normalized spatial mean error of 0.60±0.13. Moreover, results show a fast decaying learning curve for the users involved in the study. Compared to this, when the navigation task is performed by the autonomous control, 100% success rate, a time of 8.0±0.5s and a normalized spatial mean error of 0.50±0.05 are obtained. Finally, we quantitatively demonstrate how both control methodologies enable very smooth movements of the microrobot, suggesting application for any task where repeatable and dexterous movements in liquid microenvironments are key requirements.

In this paper we propose a soil penetration robotic system inspired by low friction penetration strategies in plant roots. Growth of cells at the root tip deforms soil, while sloughing cells in the cap create an interface between root and soil to reduce root-soil friction during penetration. A simple prototype, inspired by these root features and based on a tubular shaft and a soft continuum skin, was developed. The skin is kept inside the shaft and slips out and slides on its external body. This outward movement of the skin opens the soil in front of the tip and helps the system to penetrate. The skin covering the external body of shaft imitates the role of sloughing cells and provides low-friction interface between soil and shaft. Interaction between the external skin and soil gives to the system self-anchorage capabilities for the penetration. The performances of our robotic system were characterized during penetration in granular soils. The skin-soil interaction was found to be fundamental for 1) displacing the soil in front of the tip and 2) preventing backward movements of the robot by anchoring the posterior body to the soil. In order to exploit these effects some artificial hairs were added along the skin. The increased hair density (0.012 hairs/mm2) resulted in higher penetration depth of robot (about 30%).

This paper describes the design and development of a robot with six soft limbs, with the dual capability of pushing-based locomotion and grasping by wrapping around objects. Specifically, a central platform lodges six silicone limbs, radially distributed, with cables embedded. A new mechanism-specific gait, invariant regarding the number of limbs, has been implemented. Functionally, some limbs provide stability while others push and pull the robot to locomote in the desired direction. Once the robot is close to a target, one limb is elected to wrap around the object and, thanks to the particular limb structure and the soft material, a friction-based grasping is achieved. The robot is inspired by the octopus and implements the key principles of locomotion in this animal, without coping the full body structure. For this reason it works in water, but it is not restricted to this environment. The experiments show the effectiveness of the original solution in locomotion and grasping.

The octopus is a marine animal whose body has no rigid structures. It has eight arms mainly composed of muscles organized in a peculiar structure, named muscular hydrostat, that can change stiffness and that is used as a sort of a modifiable skeleton. Furthermore, the morphology of the arms and the mechanical characteristics of their tissues are such that the interaction with the environment, namely water, is exploited to simplify the control of movements. From these considerations, the octopus emerges as a paradigmatic example of embodied intelligence and a good model for soft robotics. In this paper the design and the development of an artificial muscular hydrostat are reported, underling the efforts in the design and development of new technologies for soft robotics, like materials, mechanisms, soft actuators. The first prototype of soft robot arm is presented, with experimental results that show its capability to perform the basic movements of the octopus arm (like elongation, shortening, and bending) and demonstrate how embodiment can be effective in the design of robots.

In this work, the design and development of an integrated platform for the steering of swimming microrobot is reported. The system consists of: a near-spherical soft and buoyant magnetic microrobot (with a diameter of about 500 μm) conceived for operation in liquid; a wireless magnetic steering system, including a compact magnetic field generator based on two pairs of Helmholtz and Maxwell coils; an electronic system for their driving; a control software; a joypad physical user interface; and, the micro-arena as working environment. The platform design fulfills the requirements for the “Mobility Task” of the 2011 NIST Mobile Microrobotics Challenge. The results obtained from preliminary validation experiments confirm that the microrobots can move in a fully controlled way, successfully accomplishing an intricate eight-shape path, as required, in the water filled micro-arena. In particular we achieved a maximum average speed of 0.71 mm/s and an exceptionally smooth motion.

We present the design and development of novel suction cups inspired by the octopus suckers. Octopuses use suckers for remarkable tasks and they are capable to obtain a good reversible wet adhesion on different substrates. We investigated the suckers morphology that allow octopus to attach them to different wet surfaces to obtain the benchmarks for new suction cups showing similar performances. The investigation was performed by using non-invasive techniques (i.e. ultrasonography and magnetic resonance imaging). We acquired images of contiguous sections of octopus suckers, which were used to make a 3D reconstruction aimed to obtain a CAD model perfectly equivalent to the octopus sucker in terms of sizes and anatomical proportion. The 3D information was used to develop the first passive prototypes of the artificial suction cups made in silicone. Then, in accordance with Kier and Smith's octopus adhesion model, we put in tension the water volume in the interior chamber of the artificial suction cup to obtain suction. The characterization of the passive sucker was addressed by measuring both the differential pressure between external and internal water volume of suction cup (~ 105) and the pull-off force applied to detach the substrates from the suction cup (~ 8N).

Electro-rheological (ER) fluids are smart fluids which can transform into solid-like phase by applying an electric field. This process is reversible and can be strategically used to build fluidic components for innovative soft robots capable of soft locomotion. In this work, we show the potential applications of ER fluids to build valves that simplify design of fluidic based soft robots. We propose the design and development of a composite ER valve, aimed at controlling the flexibility of soft robots bodies by controlling the ER fluid flow. We present how an ad hoc number of such soft components can be embodied in a simple crawling soft robot (Wormbot); in a locomotion mechanism capable of forward motion through rotation; and, in a tendon driven continuum arm. All these embodiments show how simplification of the hydraulic circuits relies on the simple structure of ER valves. Finally, we address preliminary experiments to characterize the behavior of Wormbot in terms of actuation forces.

-We describe the design, realization and first sea trials of a small-sized Autonomous Surface Vehicle (ASV) for environmental monitoring. The robot is being developed in the framework of the HydroNet European project [1] aiming at realizing a new multi-robot system for monitoring the quality of coastal waters, rivers and lagoons. One main innovation of the robot is the capability to measure heavy metals concentrations directly onboard using sensors ad hoc developed by the consortium. This enables the system to provide real-time measurements of heavy metals concentrations potentially changing the current water monitoring methodology in which the samples are collected by a dedicated boat and analyzed in laboratory. The robot is designed for long range missions and for lodging the onboard water analysis system. Some severe constraints imposed by the addressed scenarios are considered in the design: reduced length and limited weight for ease of transportability and deployment; low draft and protected propellers to enable the ASV to move safely in shallow waters with likely floating obstacles such as plastic bags.

We report on the design and the experimental results of DustCart, a wheeled autonomous robot for door-to-door garbage collection. DustCart is able to navigate in urban environments avoiding static and dynamic obstacles and to interact with human users. The robot is managed by an Ambient Intelligence system (AmI) through a wireless connection: it navigates to collect garbage bags to the houses of users and then moves to discharge the collected waste to a dedicated area. The architecture, navigation and localization systems are described along with the results achieved in different urban sites. In particular, a localization approach based on optical beacons was used and guaranteed position errors sufficient for a safe robot navigation. We report also the first results of a long-term experimentation of the DustCart robot in Peccioli, a small town of Tuscany (Italy). This can be considered as a first step in using robotics in the everyday life of a real town for providing a real service.

A novel approach for the design of magnetically-propelled microrobots is proposed as an effective solution for swimming in a liquid medium. While intrinsic neutral buoyancy of a microrobot per se simplifies propulsion in the liquid environments, softness makes it compliant with delicate environments, such as the human body, thus guaranteeing a safe interaction with soft structures. With this aim, two groups of soft microrobots with paramagnetic and ferromagnetic behaviors were designed, fabricated and their features were experimentally analyzed. In agreement with the theoretical predictions, in the performed trials the ferromagnetic microrobots showed orientation capabilities in response to the magnetic field that could not be achieved by the paramagnetic one. Moreover, it was observed that the ferromagnetic microrobot could reach higher speed values (maximum value of 0.73 body length/s) than the paramagnetic prototype.

Water, recognized as one of the most important and endangered resources to mankind, is very difficult to monitor in real time using conventional methods. Thanks to recent advancements in technology, the use of robots, able to fulfill missions such as sampling from aquatic environments, becomes feasible and can increase dramatically the quality of water monitoring. Due to the complications for the robot's movement in some aquatic scenarios, for instance, shallow waters or dry banks of rivers and lakes, amphibian locomotion appears to be necessary to guarantee a satisfying coverage of the monitoring activities in such areas. In this paper, we focus on developing a practical amphibian solution by introducing a pair of screw rotors, which rotate in opposite directions to generate locomotion on the ground. The primitive idea of this novel design is to enhance the versatility of a marine robot with a terrestrial locomotion without undermining its performance during the movements in the water. In particular, we elaborate the principle of this novel design and present some test results of a prototype on selected terrain types, which are similar to the target aquatic environment. We conclude the paper with some preliminary conclusions based on the analysis of the test results about effectiveness and efficiency issues.

In the domain of psychology and medical science, many experiments have been conducted referring to research on animal behaviors, to study the mechanism of mental disorders and to develop psychotropic drugs to treat them. Rodents such as rats are often chosen as experimental subjects in these experiments. However, according to some researchers, the experiments on social interactions using animals are poorly- reproducible. Therefore, we consider that the reproducibility of these experiments can be improved by using a robotic agent that interacts with an animal subject. We have developed a novel quadruped rat-inspired robot, the WR-2 (Waseda Rat No.2), based on the dimension and body structure of a mature rat. It is capable of reproducing the behaviors such as walking, mounting, rearing and grooming of the rat.

This paper describes and discusses the preliminary results of a behavioural study on robot social acceptability, which was carried out during a public demonstration in South Korea. Data was collected by means of direct observation of people behaviour during interaction with robots. The most interesting result to emerge is that of young people: they tended to react to the robots presence with extreme curiosity and, quite often, to treat them aggressively. In this paper, the word bullying is used to describe any kind of improper and violent behaviour, intended to cause damages or impede the robot operation. It is the authors' opinion that if not tackled appropriately, abuses towards robots may become a serious hindrance to their future deployment, and safety. Hence, the necessity to tackle this issue with dedicated solutions during the early phases of design.

Due to the limited resolution of both cameras and displays, acuity of artificial vision systems is currently well below the human eye. Visual acuity, in cameras as well as in animal eyes, can be increased by making smaller receptors or bigger eyes. In some applications, the size of the camera is constrained, so alternative solutions must be sought. This paper presents a robotic dual-camera vision system whose design is inspired by the visual system of jumping spiders (Salticidaefamily). The system is composed of a telephoto camera whose field of view (FOV) can be moved within the larger FOV of a wide-angle camera and allows to form a high-resolution image, i.e., an image with the FOV of the wide-angle camera, yet having the same resolution as the telephoto camera. We describe the design of the robotic system, the direct and inverse kinematics, and the image processing algorithms that allow to build the high-resolution image. Images from experiments are presented, together with a discussion on sources of errors and possible solutions. The system is particularly useful for fixed-camera monitoring or teleoperation applications, such as remote surveillance and minimally invasive surgery. The system achieves seven times higher resolution than typical commercial endoscopes.

This paper addresses the problem of autonomous localization of multiple gas or odor sources in an indoor environment with no strong airflow. In our approach, a robot iteratively builds an occupancy grid map from successive measurements of odor concentration. The resulting map shows the probability of each discrete cell in the map containing an active plume source. Our method is based on a recent adaptation of Bayesian occupancy grid mapping (OGM) to the chemical plume source localization problem. We present experimental results that demonstrate the utility of the approach.