Amphibious Environment Research Articles

Research and Implementation of Pneumatic Amphibious Soft Bionic Robot

To meet the requirements of amphibious exploration, ocean exploration, and military reconnaissance tasks, a pneumatic amphibious soft bionic robot was developed by taking advantage of the structural characteristics, motion forms, and propulsion mechanisms of the sea lion fore-flippers, inchworms, Carangidae tails, and dolphin tails. Using silicone rubber as the main material of the robot, combined with the driving mechanism of the pneumatic soft bionic actuator, and based on the theory of mechanism design, a systematic structural design of the pneumatic amphibious soft bionic robot was carried out from the aspects of flippers, tail, head–neck, and trunk. Then, a numerical simulation algorithm was used to analyze the main executing mechanisms and their coordinated motion performance of the soft bionic robot and to verify the rationality and feasibility of the robot structure design and motion forms. With the use of rapid prototyping technology to complete the construction of the robot prototype body, based on the motion amplitude, frequency, and phase of the bionic prototype, the main execution mechanisms of the robot were controlled through a pneumatic system to carry out experimental testing. The results show that the performance of the robot is consistent with the original design and numerical simulation predictions, and it can achieve certain maneuverability, flexibility, and environmental adaptability. The significance of this work is the development of a pneumatic soft bionic robot suitable for amphibious environments, which provides a new idea for the bionic design and application of pneumatic soft robots.

Amphibious Multifunctional Hydrogel Flexible Haptic Sensor with Self-Compensation Mechanism.

In recent years, hydrogel-based wearable flexible electronic devices have attracted much attention. However, hydrogel-based sensors are affected by structural fatigue, material aging, and water absorption and swelling, making stability and accuracy a major challenge. In this study, we present a DN-SPEZ dual-network hydrogel prepared using polyvinyl alcohol (PVA), sodium alginate (SA), ethylene glycol (EG), and ZnSO4 and propose a self-calibration compensation strategy. The strategy utilizes a metal salt solution to adjust the carrier concentration of the hydrogel to mitigate the resistance drift phenomenon to improve the stability and accuracy of hydrogel sensors in amphibious scenarios, such as land and water. The ExpGrow model was used to characterize the trend of the ∆R/R0 dynamic response curves of the hydrogels in the stress tests, and the average deviation of the fitted curves ϵ¯ was calculated to quantify the stability differences of different groups. The results showed that the stability of the uncompensated group was much lower than that of the compensated group utilizing LiCl, NaCl, KCl, MgCl2, and AlCl3 solutions (ϵ¯ in the uncompensated group in air was 276.158, 1.888, 2.971, 30.586, and 13.561 times higher than that of the compensated group in LiCl, NaCl, KCl, MgCl2, and AlCl3, respectively; ϵ¯ in the uncompensated group in seawater was 10.287 times, 1.008 times, 1.161 times, 4.986 times, 1.281 times, respectively, higher than that of the compensated group in LiCl, NaCl, KCl, MgCl2 and AlCl3). In addition, for the ranking of the compensation effect of different compensation solutions, the concentration of the compensation solution and the ionic radius and charge of the cation were found to be important factors in determining the compensation effect. Detection of events in amphibious environments such as swallowing, robotic arm grasping, Morse code, and finger-wrist bending was also performed in this study. This work provides a viable method for stability and accuracy enhancement of dual-network hydrogel sensors with strain and pressure sensing capabilities and offers solutions for sensor applications in both airborne and underwater amphibious environments.

3D Printing Self-Healing and Self-Adhesive Elastomers for Wearable Electronics in Amphibious Environments.

To meet the demands of challenging usage scenarios, there is an increasing need for flexible electronic skins that can operate properly not only in terrestrial environments but also extend to complex aquatic conditions. In this study, we develop an elastomer by incorporating dynamic urea bonds and hydrogen bonds into the polydimethylsiloxane backbone, which exhibits excellent autonomous self-healing and reversible adhesive performance in both dry and wet environments. A multifunctional flexible sensor with excellent sensing stability, amphibious self-healing capacity, and amphibious self-adhesive performance is fabricated through solvent-free 3D printing. The sensor has a high sensing sensitivity (GF = 45.1) and a low strain response threshold (0.25%) and can be used to detect small human movements and physiological activities, such as muscle movement, joint movement, respiration, and heartbeat. The wireless wearable sensing system assembled by coupling this device with a bluetooth transmission system is suitable for monitoring strenuous human movement in amphibious environments, such as playing basketball, cycling, running (terrestrial environments), and swimming (aquatic environments). The design strategy provides insights into enhancing the self-healing and self-adhesive properties of soft materials and promises a prospective avenue for fabricating flexible electronic skin that can work properly in amphibious environments.

The Walking Control of a Crab Biorobot in Amphibious Environment.

This article describes development of a crab biorobot that is capable of traversing diverse environments including both land and water. We have transformed a living rainbow crab into a walking biorobot by attaching wireless controller. An anatomical and physiological investigation revealed the rainbow crabs have sensory system on the carapace. Based on this finding, we implanted electrodes into the carapace. The walking direction of the robot is controlled through electrical stimulation provided by the controller. Depending on this site, the crab biorobot is induced to walk forward, leftward, and rightward in both terrestrial and underwater conditions. There is no significant difference in the mean walking direction between the two conditions. Smooth transition from land to water of the crab biorobot further demonstrates the adaptability to amphibious environment. This biorobot is compact, measuring 5 cm in carapace and weighing 50 g including the wireless controller. The crab biorobot in this scale has a potential for application narrow and unstructured in waterfront environments.

Kernmantle structured stretchable strain sensors for biomechanical sensing in amphibious environments

The burgeoning field of flexible wearable electronics, crafted from lightweight and stretchable yarns, has captured widespread attention due to their promising roles in human health monitoring and personal health management. The quintessential wearable devices demand not only exceptional comprehensive performance but also a harmonious integration of conductive yarns into an assortment of apparel to ensure comfort while capturing different signals from the human body. However, producing yarns that can accommodate high loadings of functional materials and retain superb elasticity presents an inevitable challenge. To surmount this obstacle, here, a three-dimensional (3D) braided structure is developed to achieve contact-separation between the MXene-based thermoplastic polyurethane (TPU) fiber and silver nanowires (AgNWs)-based cotton fiber. This innovative structure preserves the inherent stretchability of the TPU while enabling the integration of functional materials. The resultant kernmantle yarn sensor (KMYS) features a low strain detection limit (0.01%), high sensitivity (gauge factor up to 948.16), ultrafast response time (71 ms), wide strain detection range (0–165%), and excellent reliability and stability (>10,000 cycles). These impressive strain-sensing properties empower the KMYS to accurately track both subtle and significant strain fluctuations in real-time - ranging from the delicate pulse signals at a fingertip to the pronounced movements of joints and the pressure exerted by the foot. This work is anticipated to establish a groundbreaking and viable approach for the large-scale production of highly sensitive strain sensors, tailored for monitoring human physiological and kinematic signals under different environmental conditions.

Hydrophobic Association Hydrogel Enabled by Multiple Noncovalent Interactions for Wearable Bioelectronics in Amphibious Environments

Hydrophobic Association Hydrogel Enabled by Multiple Noncovalent Interactions for Wearable Bioelectronics in Amphibious Environments

Encapsulated stretchable amphibious strain sensors.

Soft and stretchable strain sensors have found wide applications in health monitoring, motion tracking, and robotic sensing. There is a growing demand for strain sensors in amphibious environments, such as implantable sensors, wearable sensors for swimmers/divers, and underwater robotic sensors. However, developing a sensitive, stretchable, and robust amphibious strain sensor remains challenging. This work presents an encapsulated stretchable amphibious strain sensor. The conductive layer, made of silver nanowires embedded below the surface of polydimethylsiloxane, was sandwiched by two layers of thermoplastic polyurethane. Periodic sharp cuts were introduced to change the direction of flow from across the sensor to along the conductive path defined by the opening cracks. The crack advancing and opening is controlled by a unique combination of weak/strong interfaces within the sandwich structure. The cut design and the interfacial interactions between the layers were investigated. The strain sensor exhibited a high gauge factor up to 289, a linear sensing response, a fast response time (53 ms), excellent robustness against over-strain, and stability after 16 000 loading cycles and 20 days in an aqueous saline solution. The functionality of this amphibious strain sensor was demonstrated by tracking the motion of a robotic fish, undertaking language recognition underwater, and monitoring the blood pressure of a porcine aorta. This illustrates the promising potential for this strain sensor for both underwater use and surgically implantable applications.

Leg Mechanism Design and Motion Performance Analysis for an Amphibious Crab-like Robot

Bionic-legged robots draw inspiration from animal locomotion methods and structures, demonstrating the potential to traverse irregular and unstructured environments. The ability of Portunus trituberculatus (Portunus) to run flexibly and quickly in amphibious environments inspires the design of systems and locomotion methods for amphibious robots. This research describes an amphibious crab-like robot based on Portunus and designs a parallel leg mechanism for the robot based on biological observations. The research creates the group and sequential gait commonly used in multiped robots combined with the form of the robot’s leg mechanism arrangement. This research designed the parallel leg mechanism and modeled its dynamics. Utilizing the outcomes of the dynamics modeling, we calculate the force and torque exerted on each joint of the leg mechanism during group gait and sequential gait when the robot is moving with a load. This analysis aims to assess the performance of the robot’s motion. Finally, a series of performance evaluation experiments are conducted on land and underwater, which show that the amphibious crab-like robot has good walking performance. The crab-like robot can perform forward, backward, left, and right walking well using group and sequential gaits. Simultaneously, the crab-like robot showcases faster movement in group gaits and a more substantial load capacity in sequential gaits.

3D interlocked all-textile structured triboelectric pressure sensor for accurately measuring epidermal pulse waves in amphibious environments

3D interlocked all-textile structured triboelectric pressure sensor for accurately measuring epidermal pulse waves in amphibious environments

The Art of Gleaning and Not Becoming Domesticated in Mollusc Waterworlds

ABSTRACT In the Sine-Saloum Delta, Senegal, development actors strive to ‘develop’ female mollusc gleaning. In an apparently boundless amphibious environment, domestication underlined by discursive dispossession figures as an attractive alteration of enclosure and material dispossession. It intervenes especially temporally in human and mollusc life and overlays the (material) dialectic of capitalist ‘outside’ and ‘inside’ with one of bringing humans and molluscs from an ‘archaic’ and ‘wild’ ‘outside’ into a ‘modern’ and ‘cultivated’ ‘inside’. However, domestication projects remain entangled with the unruliness of molluscs and waters, and struggle with organisational problems and the agency of gleaners. The latter seek to foster and profit from the continuous production of ‘outsides’ and ‘insides’. They attract, appropriate and undermine projects and integrate them as mere additions into their gleaning practice. In upholding their gleaning practice and complicating mollusc domestication in alliance with unruly molluscs and waters, I argue, gleaners can also resist their own domestication.

Optimal design and implementation of an amphibious bionic legged robot

Amphibious bionic robots are a valuable tool in the field of marine engineering. In this paper, a novel multi-mode amphibious bionic legged robot is proposed. The unique mechanism design ensures that all joints of the robot will not rotate continuously but will reciprocating rotate under all working modes, which greatly reduces the probability of the robot losing motion ability due to the entanglement of aquatic plants and other organisms, making the robot more suitable for the amphibious environment comparing to traditional propulsion methods such as propellers and wheels. For an efficient walking leg mechanism design, a calculation approach for the kinematics of the leg was developed and integrated into an optimization algorithm with defined boundary conditions. 29.23% increase in stride length of walking leg after optimization. By the hydrodynamic simulation and the open water test in the circulating water channel, we tested and analyzed the influence of the geometric parameters of the swimming leg on the swimming performance, providing a reference for the development of this kind of robot. This paper provides sufficient technical details and completeness, and a series of performance evaluation experiments validated that this robot has excellent movement ability in the amphibious environment.

High-sensitivity and ultralow-hysteresis fluorine-rich ionogel strain sensors for multi-environment contact and contactless sensing.

Information transduction via soft strain sensors under harsh conditions such as marine, oily liquid, vacuum, and extreme temperatures without excess encapsulation facilitates modern scientific and military exploration. However, most reported soft strain sensors struggle to meet these requirements, especially in complex environments. Herein, a class of fluorine-rich ionogels with tunable ultimate strain, high conductivity, and multi-environment tolerance are designed. Abundant ion-dipole and dipole-dipole interactions lead to excellent miscibility between the hydrophobic ionic liquid and the fluorinated polyacrylate matrix, as well as adhesion to diverse substrates in amphibious environments. The ionogel-based sensors, even in encapsulation-free form, exhibit stable operation with a negligible hysteresis (as low as 0.119%) and high sensitivity (gauge factor of up to 6.54) under amphibious conditions. Multi-environment sensing instances in contact and even contactless forms are also demonstrated. This study opens the door for the artificial syntheses of multi-environment tolerance ionic skins with robust sensing applications in soft electronics and robotics.

Design and Optimization of a Multimode Amphibious Robot With Propeller-Leg

This article describes the design, optimization, and performance evaluation of a novel multimode motion robot named SHOALBOT, which with multimode operations depends on only one type of propulsion device and can work flexibly in the amphibious environment including running on beaches, grasslands, seabed, and swimming in the water. Robots that work in water need to minimize the number of drive components to improve reliability and reduce communication pressure, our unique design enables the robot to rely on a kind of propulsion device named propeller-leg to have the ability to run rapidly in the seaside and seabed, and swim with multi-degrees-of-freedom in the water (such a propulsion system contains only four driving elements), and it can make the robot complete more work content and improve its adaptability to the environment. Running is more stable than swimming and will not disturb the animals in the water, but when the robot encounters a high obstacle with a large area coverage, switching the motion mode to the swimming mode can pass directly over obstacles instead of detouring or giving up work, this can improve work efficiency. We analyzed and optimized propeller-leg by simulation combined with the open water test, the propeller-leg's thrust in the water before and after optimization differs by 400% according to the test results. We optimized the minimum difference between the forward and reverse thrust of the propeller-leg to improve the stability of the robot movement process and optimized the difference from 25% to 3%. This article provides sufficient technical details and completeness, and through a series of performance evaluation experiments validated that the SHOALBOT has excellent movement ability in the amphibious environment compared with other published amphibious robots of the same size.

Study on the Design and Experimental Research on a Bionic Crab Robot with Amphibious Multi-Modal Movement

Bionic amphibious robots are the intersection of biology and robotics; they have the advantages of environmental adaptability and maneuverability. An amphibious robot that combines walking and swimming move modes inspired by a crab (Portunus) is presented in this article. The outstanding characteristic of the robot is that its environmental adaptability relies on the bionic multi-modal movement, which is based on two modular bionic swimming legs and six modular walking legs. We designed the biomimetic crab robot based on the biological observation results. The design, analysis, and simulation of its structure and motion parameters are introduced in this paper. The swimming propulsion capability and the walking performance are verified through indoor, pool, and seaside experiments. In conclusion, the designed bionic crab robot provides a platform with practical application capabilities in amphibious environment detection, concealed reconnaissance, and aquaculture.

Anatomical and histochemical structures of Cyperus rotundus L. facilitate success in amphibious environments

The perennial Cyperus rotundus (Cyperaceae) is a noxious weed worldwide that tolerates the extreme environments of the Three Gorges Reservoir, China. Using brightfield and epifluorescence microscopy, we investigated the anatomical and histochemical features that allow this species to thrive in amphibious environments. The apoplastic barriers of C. rotundus consisted of an endodermis, a uniseriate exodermis, and a cuticle in the roots, rhizomes, and culms, respectively, as well as suberized stele and primary xylem poles. These barriers may help C. rotundus to retain oxygen and control water-solute exchanges under anoxic conditions. The mechanical tissues of C. rotundus included lignified sclerenchyma rings and sclerenchyma fibers in the roots, shoots, rhizomes, and tubers. The air spaces had lysed aerenchyma in the roots, leaves, and rhizomes, while schizogenous aerenchyma was observed in the culms. Neither lysed nor schizogenous aerenchyma was found in the tubers. C. rotundus is a typical C4 species with Kranz anatomy; chloroplasts were present in the inner sheaths and parenchymatous sheaths. Thus, our analyses identified several anatomical and histochemical features that may facilitate the adaptive success of C. rotundus in amphibious environments.

Granular Resistive Force Theory Extension for Saturated Wet Sand Ground

Amphibious environments formed from sand and water present a formidable challenge to the running motion of field robots, as the mixing of granular media (GM) and water makes the force laws of robotic legs more complicated during robot running. To this end, we extended the granular resistive force theory (RFT) to saturated wet granular media, named saturated granular RFT (SGRFT), which can be suitable for saturated wet sand submerged in water. This method can extend RFT for dry GM to saturated wet granular media (SWGM) by using the method’s velocity and depth coefficient. The force laws of the robotic legs in dry GM and SWGM were tested, compared, and analyzed. The difference in force laws between the two kinds of media, from the sensitivity to speed (10 mm/s~50 mm/s) and depth (0~60 mm), was calculated. More than 70% of the prediction results of the horizontal resistive force using SGRFT have an error of less than 6%. The effectiveness of the SGRFT in legged robots is proved by simulation and testing of three kinds of legs. The difference in force laws when running is proved by the experiments of the robot equipped with the propeller-leg in dry GM and SWGM, which is vital for amphibious robots working in shoal environments (including dry GM and SWGM ground).

Power generation performance of a spherical robot with a pendulum in an amphibious environment

Power generation performance of a spherical robot with a pendulum in an amphibious environment

Miniature Amphibious Robot Actuated by Rigid-Flexible Hybrid Vibration Modules.

Amphibious robots can undertake various tasks in terrestrial and aquatic environments for their superior environmental compatibility. However, the existing amphibious robots usually utilize multi‐locomotion systems with transmission mechanisms, leading to complex and bulky structures. Here, a miniature amphibious robot based on vibration‐driven locomotion mechanism is developed. The robot has two unique rigid‐flexible hybrid modules (RFH‐modules), in which a soft foot and a flexible fin are arranged on a rigid leg to conduct vibrations from an eccentric motor to the environment. Then, it can run on ground with the soft foot adopting the friction locomotion mechanism and swim on water with the flexible fin utilizing the vibration‐induced flow mechanism. The robot is untethered with a compact size of 75 × 95 × 21 mm3 and a small weight of 35 g owing to no transmission mechanism or joints. It realizes the maximum speed of 815 mm s–1 on ground and 171 mm s–1 on water. The robot, actuated by the RFH‐modules based on vibration‐driven locomotion mechanism, exhibits the merits of miniature structure and fast movements, indicating its great potential for applications in narrow amphibious environments.

A novel soft-rigid wheeled crawling robot with high payload and passing capability

AbstractSoft crawling robots have been significantly studied in recent decades. However, moving in amphibious environment, high payload capability, and passing through complex ground have always been challenges for soft crawling robots. For these problems, this article presents an amphibious soft-rigid wheeled crawling robot (SRWCR) consists of a soft-rigid body actuated by two soft pneumatic actuators (SPAs), four wheels, and four annular soft bladders (ASBs) as brakes. By programming the actuation sequences of the two SPAs and four ASBs, SRWCR can achieve two basic modes of locomotion: linear motion and turning. Based on the energy conservation law, we have developed analytical models to interpret the static actuation performance of SPA, including linear and bending deformations. Furthermore, with the help of fast response and waterproof of SPA and ASB, SRWCR can achieve a linear speed of 14.97 mm/s, a turning speed of 5.63°/s, and an underwater locomotion speed of 13 mm/s, which demonstrates the excellent locomotion performance of SRWCR in amphibious environment. In addition, SRWCR can also achieve multiple impressive functions, including carrying a payload of 2 kg at the moving speed of 11.18 mm/s, passing through various complex ground such as the grass ground and sand ground, and so on, obstacle navigation in confined space. Compared with the existing soft crawling robots, with the help of the soft-rigid body and wheeled structure, SRWCR has the best payload and passing capability, which indicates the potential advantage of SRWCR in the design of functional robots.

Bioinspired Amphibious Origami Robot with Body Sensing for Multimodal Locomotion.

Animals have long captured the inspirations of researchers in robotics with their unrivaled capabilities of multimodal locomotion on land and in water, achieved by functionally versatile limbs. Conventional soft robots show infinite degrees-of-freedom (DOFs), making it hard to be actuated and conduct multiple movements especially for multimodal locomotion in different environments. An origami robot, which is capable of reversibly transforming the robotic shape by simple creases folding/unfolding, reveals advantages for imitating flexible movements of animals, thus drawing more and more attention. However, it poses substantial technological challenges for bioinspired design, sensing, and actuation of origami robots that can generate multimodal locomotion through performing complex morphologic deformation in different scenarios such as land and water. To relieve this issue, we propose a novel bioinspired amphibious origami machine with body sensing for multimodal locomotion. In this work, inspired by the peristalsis of inchworm and human swimming behaviors, a unique origami body with legs and origami arms is developed to enable the integrated robot to move both on land and in water. Instead of traditional electronic sensors, we design highly stretchable and foldable layer resistive sensor with conductive polymers coated onto the origami body to achieve robotic sensing such as obstacle detection. In addition, with detailed analysis, a self-designed pneumatic system of time division, multiplexing, and serialization is adopted to efficiently control the robot with high DOF. We eventually demonstrate that the fabricated origami robot successfully moves in amphibious environments, which is capable of crawling forward, turning right/left, and swimming. We expect that this work indicates contributions to advanced origami design, actuation control, and body sensor of the bioinspired robot with multimodal locomotion for broadly practical applications.