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Hummingbirds demonstrate remarkable robustness to wing defects by maintaining stable hovering during the molting process. However, mimicking these capabilities in flapping-wing robots presents significant challenges. To investigate the effectiveness of various controllers in maintaining the attitude of a hummingbird-mimetic flapping-wing robot against external disturbances under different wing defects, this study implemented a PD controller, a PID controller, and a three-loop feedback controller with a disturbance observer (3L-DOB controller). The flapping-wing robot features a pair of wings and controls its body's yaw, pitch, and roll rotations by modulating the tension of wing membranes and the neutral positions of wing torsion. The performance of these controllers was evaluated through semi-tethered experiments on a gimbal, employing three Wing Sets: intact wings, one wing was defective, and both wings were defective. The defective wing emulated hummingbird wing during molting, in which the wing area was cropped by 14.1%. As a result, the 3L-DOB controller showed the best performance in terms of responsiveness and accuracy across all Wing Sets, while the PID controller also achieved comparable performance. [ABSTRACT FROM AUTHOR]

The proprioceptive sensory reflex (e.g. stretch reflex) plays an important role in perturbed arm stabilization. Neuroscience studies have widely identified the heteronymous spinal pathways in the human arm, which may contribute to stabilized movement. However, their interactions in living systems pose challenges for specific functional investigations through human experiments. Therefore, this paper concentrates on understanding the effects of two heteronymous pathways, specifically the transmission of monoarticular sensory feedback to innervate biarticular muscles, using the robot. We replicate specific reflex pathways on a 2-DoF musculoskeletal robot equipped with pneumatic artificial muscles. By adjusting the weights of pathways, which resemble human motor control, we evaluate our robot arm performance under the forearm and upper arm disturbances. The outcomes validate their effects on regulating biarticular muscle stimulation, resulting in more stable and coordinated end-effectory trajectories. These reflexive pathways provide insights into the mechanisms underlying human arm perturbations and stabilization. Additionally, the proposed bioinspired system with applicable reflex weights holds great potential in the adaptive response of musculoskeletal robots, guiding robotics researchers in controller design. [ABSTRACT FROM AUTHOR]

This paper considers the design, manufacture, and testing of a prototype "soft–stiff" worm-inspired robot referred to herein, as the PneumaticallyActuated PeristaLtic Advancing Modular (PALAM) robot. The robot has a modular structure, mimicking the segmented nature of earthworms, and each segment is individually actuated by a set of three pneumatic artificial muscles (PAMs). The PAMs contract when inflated by pressurised air, generating a pulling force and fulfilling the role of biological muscles in the robot. The PAMs are made from the elastomer silicone rubber, which affords the robot flexibility and enables a wide range of real-life applications. A control-system is designed which can inflate any PAM on demand, and hence replicate the peristaltic motion of earthworms in the PALAM robot. Finally, this paper discusses a successful, low-cost, and widely accessible approach for the manufacture of the PAMs utilised herein. The PAMs can be scaled dimensionally and made from different materials with varying mechanical properties and behaviours, meaning that they are suitable for use in a wide range of robotics applications. [ABSTRACT FROM AUTHOR]

This research aims to advance the current state-of-the-art of earthworm-like robots by extending the gait study from rectilinear and planar locomotion to spatial locomotion. In detail, the following five important but largely unaddressed issues are tackled in this paper, including the multibody kinematic modeling of the robot with spatial locomotion capability, 3D gait generation algorithm, spatial locomotion mode classification, spatial locomotion performance evaluation, and 3D gait planning. Based on the multibody model of the metameric earthworm-like robot and learning from the retrograde peristalsis wave, a gait-generation algorithm is proposed for generating all admissible 3D locomotion gaits. The 3D locomotion can be classified into four major types (rectilinear, sidewinding, circular, and cycloid), and further, ten modes with their defining conditions in terms of the gait parameters being derived. Among them, several spatial locomotion modes, such as the 3D cycloid locomotion, are uncovered for the first time. For each mode, different kinematic indexes, including the average (axial) velocity and the circumradius of the trajectory, are evaluated to comprehensively clarify the relationship between the locomotion performance and the gait parameters. Moreover, aiming at reaching the target both quickly and precisely, 3D gait planning is also studied. With contradictory objectives, the Pareto front is determined via the genetic algorithm so that a trade-off between the proximity and speed to the target can be achieved. [ABSTRACT FROM AUTHOR]

The continuous jumping of bioinspired robots in 3D spaces can greatly improve its motion flexibility, which is one of the highlights of research on jumping robots. However, most existing jumping robots can only move in a plane, and achieving stable continuous steering jumping is difficult. In this study, a realization method of stable continuous steering jumping for a bioinspired jerboa robot is proposed. On the basis of the jumping mechanism of the jerboa, the robot mechanism model is established, and the factors affecting motion feasibility and performance are analyzed in detail. Then, mathematical models of the stability indices of the robot jumping on uneven ground with redundant driving are established. Based on the proposed improved bee colony algorithm, the motion parameters and driving parameters can be determined. Simulation results show that the robot can realize stable continuous steering jumping in different terrains along the expected trajectory, thus proving the feasibility of the method proposed in this study. This study provides a theoretical reference for the high‐speed flexible motion of legged robots in 3D spaces. [ABSTRACT FROM AUTHOR]

Abstract Legged robots use isolated footholds to support, which have the merit of good terrain trafficability but lack speed ability. In contrast, wheeled robots have the advantages of high speed and efficiency but only run on flat roads. To improve the moving speed and terrain adaptability of the legged robot, this paper proposes a bioinspired multimode octopod robot with rolling, walking, and obstacle-surmounting modes. First, inspired by the multimode locomotion of the Cebrennus rechenbergi spider, the high-speed mobility of the legged robot is realized in involute kick-rolling mode through the extendable appendages. Then, the foot and appendage trajectories are analyzed by kinematic method and optimized for walking stability. Based on the static and the kinematic analyses, the terrain adaptability is improved by adhesive obstacle-surmounting mode with the assistance of the appendages affiliated to the main feet. The deformable trunk with one DoF is designed to switch between three modes. Finally, a series of dynamic simulations and experiments are carried out to verify the theoretical analyses of the adhesive obstacle-surmounting mode and the mobility of the involute kick-rolling mode. It is shown that the multimode octopod robot can integrate the advantages of high speed and good terrain trafficability from different types of robots and is suitable for performing tasks in unstructured terrains.

This paper considers the design, manufacture, and testing of a prototype “soft–stiff” worm-inspired robot referred to herein, as the PneumaticallyActuated PeristaLtic Advancing Modular (PALAM) robot. The robot has a modular structure, mimicking the segmented nature of earthworms, and each segment is individually actuated by a set of three pneumatic artificial muscles (PAMs). The PAMs contract when inflated by pressurised air, generating a pulling force and fulfilling the role of biological muscles in the robot. The PAMs are made from the elastomer silicone rubber, which affords the robot flexibility and enables a wide range of real-life applications. A control-system is designed which can inflate any PAM on demand, and hence replicate the peristaltic motion of earthworms in the PALAM robot. Finally, this paper discusses a successful, low-cost, and widely accessible approach for the manufacture of the PAMs utilised herein. The PAMs can be scaled dimensionally and made from different materials with varying mechanical properties and behaviours, meaning that they are suitable for use in a wide range of robotics applications.

Legged robots use isolated footholds to support, which have the merit of good terrain trafficability but lack speed ability. In contrast, wheeled robots have the advantages of high speed and efficiency but only run on flat roads. To improve the moving speed and terrain adaptability of the legged robot, this paper proposes a bioinspired multimode octopod robot with rolling, walking, and obstacle-surmounting modes. First, inspired by the multimode locomotion of the Cebrennus rechenbergi spider, the high-speed mobility of the legged robot is realized in involute kick-rolling mode through the extendable appendages. Then, the foot and appendage trajectories are analyzed by kinematic method and optimized for walking stability. Based on the static and the kinematic analyses, the terrain adaptability is improved by adhesive obstacle-surmounting mode with the assistance of the appendages affiliated to the main feet. The deformable trunk with one DoF is designed to switch between three modes. Finally, a series of dynamic simulations and experiments are carried out to verify the theoretical analyses of the adhesive obstacle-surmounting mode and the mobility of the involute kick-rolling mode. It is shown that the multimode octopod robot can integrate the advantages of high speed and good terrain trafficability from different types of robots and is suitable for performing tasks in unstructured terrains. [ABSTRACT FROM AUTHOR]

This comprehensive review delves into the realm of bipedal wheel-legged robots, focusing on their design, control, and applications in assistive technology and disaster mitigation. Drawing insights from various fields such as robotics, computer science, and biomechanics, it offers a holistic understanding of these robots' stability, adaptability, and efficiency. The analysis encompasses optimization techniques, sensor integration, machine learning, and adaptive control methods, evaluating their impact on robot capabilities. Emphasizing the need for adaptable, terrain-aware control algorithms, the review explores the untapped potential of machine learning and soft robotics in enhancing performance across diverse operational scenarios. It highlights the advantages of hybrid models combining legged and wheeled mobility while stressing the importance of refining control frameworks, trajectory planning, and human-robot interactions. The concept of integrating soft and compliant mechanisms for improved adaptability and resilience is introduced. Identifying gaps in current research, the review suggests future directions for investigation in the fields of robotics and control engineering, addressing the evolution and terrain adaptability of bipedal wheel-legged robots, control, stability, and locomotion, as well as integrated sensory and perception systems, microcontrollers, cutting-edge technology, and future design and control directions. [ABSTRACT FROM AUTHOR]

Vertebrates achieve a high degree of flexibility and skillful performance via a musculoskeletal system consisting of multiple joints. These joints are simultaneously driven by some multi-articular muscles, which run over two or more joints and synchronize the musculoskeletal system. However, when multi-articular muscles contract, buckling may occur in the system if each joint is not adequately supported, such as by monoarticular muscles or intervertebral discs, and we previously investigated the stability conditions for avoiding such buckling by calculating the potential energy of the muscle elasticity. Although in our previous work we considered only the muscles themselves, actual animal muscles are surrounded and constrained by fascia, other muscles, and skin, which may also influence the stability of the musculoskeletal system. Based on this characteristic, in this study, we examined the effect of the surrounding elastic elements that constrain the muscle pathway on the stability of the musculoskeletal system. We analyzed the static stability of the system with respect to potential energy using a muscle path restraint model of the serial link mechanism driven by McKibben-type pneumatic artificial muscles. Moreover, we confirmed the analytical result by conducting an experiment using a six-joint serial link robot driven by antagonistically arranged pneumatic artificial muscles. The results revealed that the restraint of the muscle path influences the stability of the system, and that the support of each joint and restraint is critical for the stability of the system.

Soft robots demonstrate an impressive ability to adapt to objects and environments. However, current soft mobile robots often use a single mode of movement. This gives soft robots good locomotion performance in specific environments but poor performance in others. In this paper, we propose a leg–wheel mechanism inspired by bacterial flagella and use it to design a leg–wheel robot. This mechanism employs a tendon-driven continuum structure to replicate the bacterial flagellar filaments, while servo and gear components mimic the action of bacterial flagellar motors. By utilizing twisting and swinging motions of the continuum structure, the robot achieves both wheeled and legged locomotion. The paper provides comprehensive descriptions and detailed kinematic analysis of the mechanism and the robot. To verify the feasibility of the robot, a prototype was implemented, and experiments were performed on legged mode, wheeled mode, and post-overturning motion. The experimental results demonstrate that the robot can achieve legged and wheeled motions. Moreover, it is also demonstrated that the robot still has mobility after overturning. This expands the applicability scenarios of the current soft mobile robot. [ABSTRACT FROM AUTHOR]

Annelids such as earthworms are considered to have central pattern generators (CPGs) that generate rhythms in neural circuits to coordinate the deformation of body segments for effective locomotion. At present, the states of earthworm‐like robot segments are often assigned holistically and artificially by mimicking the earthworms' retrograde peristalsis wave, which is unable to adapt their gaits for variable environments and tasks. This motivates the authors to extend the bioinspired research from morphology to neurobiology by mimicking the CPG to build a versatile framework for spontaneous motion control. Here, the spatiotemporal dynamics is exploited from the coupled Hopf oscillators to not only unify the two existing gait generators for restoring temporal‐symmetric phase‐coordinated gaits and discrete gaits but also generate novel temporal‐asymmetric phase‐coordinated gaits. Theoretical and experimental tests consistently confirm that the introduction of temporal asymmetry improves the robot's locomotion performance. The CPG‐based controller also enables seamless online switching of locomotion gaits to avoid abrupt changes, sharp stops, and starts, thus improving the robot's adaptability in variable working scenarios. [ABSTRACT FROM AUTHOR]

This article presents the design and the experimental tests of a bioinspired robot mimicking the cownose ray. These fish swim by moving their large and flat pectoral fins, creating a wave that pushes backward the surrounding water so that the fish is propelled forward due to momentum conservation. The robot inspired by these animals has a rigid central body, housing motors, batteries, and electronics, and flexible pectoral fins made of silicone rubber. Each of them is actuated by a servomotor driving a link inside the leading edge, and the traveling wave is reproduced thanks to the flexibility of the fin itself. In addition to the pectoral fins, two small rigid caudal fins are present to improve the robot's maneuverability. The robot has been designed, built, and tested underwater, and the experiments have shown that the locomotion principle is valid and that the robot is able to swim forward, perform left and right turns, and do floating or diving maneuvers. [ABSTRACT FROM AUTHOR]

Abstract Annelids such as earthworms are considered to have central pattern generators (CPGs) that generate rhythms in neural circuits to coordinate the deformation of body segments for effective locomotion. At present, the states of earthworm‐like robot segments are often assigned holistically and artificially by mimicking the earthworms’ retrograde peristalsis wave, which is unable to adapt their gaits for variable environments and tasks. This motivates the authors to extend the bioinspired research from morphology to neurobiology by mimicking the CPG to build a versatile framework for spontaneous motion control. Here, the spatiotemporal dynamics is exploited from the coupled Hopf oscillators to not only unify the two existing gait generators for restoring temporal‐symmetric phase‐coordinated gaits and discrete gaits but also generate novel temporal‐asymmetric phase‐coordinated gaits. Theoretical and experimental tests consistently confirm that the introduction of temporal asymmetry improves the robot's locomotion performance. The CPG‐based controller also enables seamless online switching of locomotion gaits to avoid abrupt changes, sharp stops, and starts, thus improving the robot's adaptability in variable working scenarios.

Abstract Artificial multiarticular musculoskeletal systems consisting of serially connected links driven by monoarticular and multiarticular muscles, which are often inspired by vertebrates, enable robots to elicit dynamic, elegant, and flexible movements. However, serial links driven by multiarticular muscles can cause unstable motion (e.g., buckling). The stability of musculoskeletal mechanisms driven by antagonistic multiarticular muscles depends on the muscle configuration, origin/insertion of muscles, spring constants of muscles, contracting force of muscles, and other factors. We analyze the stability of a multi-serial-link mechanism driven by antagonistic multiarticular muscles aiming to avoid buckling and other undesired motions. We theoretically derive the potential energy of the system and the stable condition at the target point, and validate the results through dynamic simulations and experiments. This paper presents the static stability criteria of serially linked robots, which are redundantly driven by monoarticular and multiarticular muscles, resulting in the design and control guidelines for those robots.

• Analysis of wave-like robotic locomotion in a circular canal. • There are four distinct contact cases for crawling, considering robot geometry. • The influence of canal width, curvature, robot geometry, and COF are considered. • A multibody dynamic simulation was developed and validated. • Experimental results validate the models. In this paper, we analyze the locomotion of a wave robot crawling in a curved canal between rigid walls. We determine the conditions for crawling, considering the robot geometry, orientation, wall curvature, canal width, and friction coefficients. Initially, we present an analytical model of the different cases of crawling and conditions for advancement. We found four cases of crawling: one where the robot touches only the outer wall, two with one contact point each on the outer and inner walls, and a third where the robot has two contact points with the outer wall and one with the inner wall. Subsequently, we introduce a multibody numerical simulation, which accounts for sliding along the wall and over the ground surface. The simulation allows one to validate our analytical results and analyze the robot's behavior under different conditions. Finally, we present validating results of multiple experiments conducted with our SAW robot. This analysis encompasses all types of crawling robots with internal thrust mechanisms that are not based on contact with the side walls of the pipe or canal. [ABSTRACT FROM AUTHOR]

Landing on vertical surfaces in challenging environments is a critical ability for multimodal robots—it allows the robot to hold position above the ground without expending energy to hover. Asian flat‐tailed geckos (Hemidactylus platyurus) are observed to glide and perch on vertical surfaces by relying on their tail and body morphology, potentially reducing the control effort to perch. This novel perching mechanism using a bioinspired physical model is discussed and its tail and body parameters to determine their influence on perching success and the kinematics of the gecko's dynamic landing maneuver are adjusted. Perching performance is evaluated by changing the model's torso and tail stiffness. Combining a compliant torso and stiff tail enables the model to passively perch on a vertical substrate with a success rate >90%, compared with ≈10% without a tail attached. A compliant torso is necessary to absorb the in‐flight kinetic energy and accommodate the uncertainties in approach conditions. Similar to the gecko's perching strategy, the stiff tail pushes against the substrate, preventing the model from falling backward head over heels. These findings highlight the critical role of tail and material stiffness for perching and provide a simplified mechanism to impart perching capabilities in robots. [ABSTRACT FROM AUTHOR]

Landing on vertical surfaces in challenging environments is a critical ability for multimodal robots—it allows the robot to hold position above the ground without expending energy to hover. Asian flat‐tailed geckos (Hemidactylus platyurus) are observed to glide and perch on vertical surfaces by relying on their tail and body morphology, potentially reducing the control effort to perch. This novel perching mechanism using a bioinspired physical model is discussed and its tail and body parameters to determine their influence on perching success and the kinematics of the gecko's dynamic landing maneuver are adjusted. Perching performance is evaluated by changing the model's torso and tail stiffness. Combining a compliant torso and stiff tail enables the model to passively perch on a vertical substrate with a success rate >90%, compared with ≈10% without a tail attached. A compliant torso is necessary to absorb the in‐flight kinetic energy and accommodate the uncertainties in approach conditions. Similar to the gecko's perching strategy, the stiff tail pushes against the substrate, preventing the model from falling backward head over heels. These findings highlight the critical role of tail and material stiffness for perching and provide a simplified mechanism to impart perching capabilities in robots.

Soft robots demonstrate an impressive ability to adapt to objects and environments. However, current soft mobile robots often use a single mode of movement. This gives soft robots good locomotion performance in specific environments but poor performance in others. In this paper, we propose a leg–wheel mechanism inspired by bacterial flagella and use it to design a leg–wheel robot. This mechanism employs a tendon-driven continuum structure to replicate the bacterial flagellar filaments, while servo and gear components mimic the action of bacterial flagellar motors. By utilizing twisting and swinging motions of the continuum structure, the robot achieves both wheeled and legged locomotion. The paper provides comprehensive descriptions and detailed kinematic analysis of the mechanism and the robot. To verify the feasibility of the robot, a prototype was implemented, and experiments were performed on legged mode, wheeled mode, and post-overturning motion. The experimental results demonstrate that the robot can achieve legged and wheeled motions. Moreover, it is also demonstrated that the robot still has mobility after overturning. This expands the applicability scenarios of the current soft mobile robot.

Artificial multiarticular musculoskeletal systems consisting of serially connected links driven by monoarticular and multiarticular muscles, which are often inspired by vertebrates, enable robots to elicit dynamic, elegant, and flexible movements. However, serial links driven by multiarticular muscles can cause unstable motion (e.g., buckling). The stability of musculoskeletal mechanisms driven by antagonistic multiarticular muscles depends on the muscle configuration, origin/insertion of muscles, spring constants of muscles, contracting force of muscles, and other factors. We analyze the stability of a multi-serial-link mechanism driven by antagonistic multiarticular muscles aiming to avoid buckling and other undesired motions. We theoretically derive the potential energy of the system and the stable condition at the target point, and validate the results through dynamic simulations and experiments. This paper presents the static stability criteria of serially linked robots, which are redundantly driven by monoarticular and multiarticular muscles, resulting in the design and control guidelines for those robots. [ABSTRACT FROM AUTHOR]

In the past two decades, unmanned amphibious robots have proven the most promising and efficient systems ranging from scientific, military, and commercial applications. The applications like monitoring, surveillance, reconnaissance, and military combat operations require platforms to maneuver on challenging, complex, rugged terrains and diverse environments. The recent technological advancements and development in aquatic robotics and mobile robotics have facilitated a more agile, robust, and efficient amphibious robots maneuvering in multiple environments and various terrain profiles. Amphibious robot locomotion inspired by nature, such as amphibians, offers augmented flexibility, improved adaptability, and higher mobility over terrestrial, aquatic, and aerial mediums. In this review, amphibious robots’ locomotion mechanism designed and developed previously are consolidated, systematically The review also analyzes the literature on amphibious robot highlighting the limitations, open research areas, recent key development in this research field. Further development and contributions to amphibious robot locomotion, actuation, and control can be utilized to perform specific missions in sophisticated environments, where tasks are unsafe or hardly feasible for the divers or traditional aquatic and terrestrial robots.

Penetrating planetary regolith is extremely important to explore the secrets inside extraterrestrial celestial bodies. Applying the concept and method of bionics to endow planetary regolith-burrowing robots (PRBRs) with elegant and flexible mobility as natural creatures is gradually becoming a research hotspot in the field of planetary robotics. Compared with traditional penetrating methods, such as drilling and excavation, bioinspired burrowing methods are still seldom studied. This work presents a detailed review of the progress and perspective of bioinspired PRBRs. According to the burrowing mechanisms and strategies of creatures, the current bioinspired PRBRs are divided into seven categories, namely wriggling, undulating, dual-anchoring, grabbing-pushing, reciprocating, granular fluidizing methods inspired by animals, and root growth method inspired by plants. The general characteristics of these robots are summarized in-depth, and the advantages and disadvantages are compared. Then, the key technologies of determining the functionalities and performance of bioinspired PRBRs are comprehensively analyzed, including bioinspired mechanism design, motion control, robot-regolith interaction, and terrestrial validation. Finally, the development trend of bioinspired PRBRs is presented, including new mechanisms and materials, autonomous burrowing control, and intelligent perception and communication. [ABSTRACT FROM AUTHOR]

This article presents the design and the experimental tests of a bioinspired robot mimicking the cownose ray. These fish swim by moving their large and flat pectoral fins, creating a wave that pushes backward the surrounding water so that the fish is propelled forward due to momentum conservation. The robot inspired by these animals has a rigid central body, housing motors, batteries, and electronics, and flexible pectoral fins made of silicone rubber. Each of them is actuated by a servomotor driving a link inside the leading edge, and the traveling wave is reproduced thanks to the flexibility of the fin itself. In addition to the pectoral fins, two small rigid caudal fins are present to improve the robot’s maneuverability. The robot has been designed, built, and tested underwater, and the experiments have shown that the locomotion principle is valid and that the robot is able to swim forward, perform left and right turns, and do floating or diving maneuvers.

The field of soft robotics is rapidly evolving, and there is a growing interest in developing soft robots with bioinspired features for use in various applications. This research presented the design and development of 3D-printed origami actuators for a soft robot with amphibious locomotion and tongue hunting capabilities. Two different types of programmable origami actuators were designed and manufactured, namely Z-shaped and twist tower actuators. In addition, two actuator variations were developed based on the Z-shaped actuator, including the pelvic fin and the coiling/uncoiling types. The Z-shaped actuators were used for the rear legs to facilitate the locomotion of the water-like frogs. Meanwhile, the twisted tower actuators were used for the rotation joints in the forelegs and for locomotion on land. The pelvic fin actuator was developed to imitate the land locomotion of the mudskipper, and the coiling/uncoiling actuator was designed for tongue hunting motion. The origami actuators and soft robot prototype were tested through a series of experiments, which showed that the robot was capable of efficiently moving in water and on land and performing tongue hunting motions. Our results demonstrate the effectiveness of these actuators in producing the desired motions and provide insights into the potential of applying 3D-printed origami actuators in the development of soft robots with bioinspired features.

In this paper, we develop a soft climbing robot made of silicone. Octopus-like behaviour is realized by a simple mechanism utilizing the dynamics of the soft body, and the robot can grasp various objects of unknown shape. In addition, by inching its truck, it can climb various columnar objects. Experiments, using pipes, long balloons, and natural trees, are conducted to evaluate the effectiveness of the proposed robot. [ABSTRACT FROM AUTHOR]

The one-degree-of-freedom (DOF) mechanism has a simple structure, convenient control, and high stiffness, and it has been applied in many micro jumping robots. Meanwhile, the six- and eight-bar mechanisms can satisfy more complex motion requirements than the four-bar jumping leg mechanism and they have good application prospects. However, the lack of effective design methods limits the application range of these mechanisms. In this work, a type and dimensional integration synthesis method was proposed with the one-DOF six-bar leg mechanism as the research object. The initial tibia and femur were determined based on the kinematic chain atlas, and configuration design was implemented through the superposition of links. When a closed chain was formed in the superposition process, the feasible range of the link length was analyzed by considering the constraint conditions. The proposed method innovatively establishes the relationship between the kinematic chain atlas and the configuration, and the feasible length ranges of the links can be quickly obtained simultaneously. Several examples were provided to prove the feasibility of the kinematic synthesis method. This method provides a useful reference for the design of one-DOF mechanisms. [ABSTRACT FROM AUTHOR]

In this paper, we present a milliscale-integrated jumping–crawling robot that can adjust its launch trajectory and upright itself. This multimodal robot shows an enhanced performance of overcoming obstacles compared with a robot with a single locomotion mode. To make this possible, the robot uses a newly developed jumping module with improved energy storing capacity and a height-adjustable active clutch. The jumping module utilizes both linear springs and torsional springs to maximize the energy-storing capacity under the given limit of structural robustness. To adjust the quantity of stored energy and release the energy at any state, an active clutch mechanism based on a single dc motor is developed, which enables the robot to control both jump timing and height. Also, an active shell allows the robot to upright itself after landing and to continue jumping and crawling. The jumping module and the shell are integrated with the lightweight VelociRoACH crawler. To show the usability in real-world applications, the integrated jumping–crawling robot is tested on the cluttered terrain. In result, the robot reaches a target using jumping, crawling, and self-righting. [ABSTRACT FROM AUTHOR]

SUMMARY: This paper reports the design, analysis, and control of a miniature vibration-driven planar locomotion robot called Shell. A vibration-driven system is able to achieve locomotion based on internal oscillations and anisotropic friction forces. In this robot design, two parallel oscillators are employed to provide propelling forces, and a blade-like support is designed to generate anisotropic frictional contact with the ground. If the two parallel oscillators are of different frequencies and amplitudes, two-dimensional locomotion of the robot can be achieved. To predict the robot's planar locomotion, a dynamic model is developed. Controlling the robot's locomotion and especially, the locomotion modes can be achieved by adjusting the vibration frequencies of the two internal oscillators. Experimental results show that Shell can be controlled to move rectilinearly and along circles with certain curvatures. In addition, by combining these basic trajectories, Shell can move freely on a horizontal plane. [ABSTRACT FROM AUTHOR]

It remains a great challenge for a biomimetic dolphin robot to leap out of the water by reason of requirements for very high speed and exquisite motion control. In this paper, we estimate the minimum exit speed that allows the dolphin to completely leap out of the water, and for the first time, we build a self-contained leaping dolphin robot with commercially available actuators and power supply. To quantify the possible impact of the body length on the minimum exit speed during the leap, we employ a rigid body model rather than a particle model to numerically evaluate the leaping process. Furthermore, a robotic prototype intended for leap motions is created, with particular emphasis on streamlining and high-thrust tail propulsive mechanism designs in conjunction with a passive control strategy for the dorsoventral propulsion. Underwater tests on the untethered dolphin robot demonstrate the effectiveness of the proposed methods and mechatronic designs. We found that the dolphin robot successfully performed leaps with a length-specific speed of over 2.3 body lengths per second, and an emergence angle ranging between 35 and 60 ${}^{\circ}$. [ABSTRACT FROM PUBLISHER]

Jellyfish uses jet propulsion to achieve a diversity of propulsion modes in the water. In this article, a miniature jellyfish-inspired swimming robot is designed and built, which is capable of executing horizontal and vertical propulsion and maneuvers. In order to imitate the jellyfish in terms of morphology and kinematics, the robotic jellyfish is designed to be comprised of a streamlined head, a cavity shell, four separate drive units with bevel gears, and a soft outer skin encasing the drive units. A combination of four six-bar linkage mechanisms that are centrally symmetric is adopted as the driver to regulate the phases of contraction and relaxation of the bell-shaped body. Furthermore, a triangle wave generator is incorporated to generate rhythmic drive signals, which is implemented on the microcontroller. Through independent and coordinated control of the four drive units, the robotic jellyfish is able to replicate various propulsion modes similar to real jellyfish. Aquatic tests on the actual robot verify the effectiveness of the formed design scheme along with the proposed control methods. [ABSTRACT FROM AUTHOR]

In gripping devices, adapting to highly unstructured environments such as irregularly shaped objects and surfaces continues to be challenging. To achieve safe and reliable gripping, many researchers have employed various underactuated mechanisms such as differential and compliant mechanisms. All these mechanisms have demonstrated successful gripping performances. They, however, have hardly considered scalability issues of underactuated mechanisms originating from additional force transmissions and onerous mechanism assembly. In this paper, we propose a structurally simple and scalable underactuated mechanism. The mechanism is demonstrated on a gripping device called the “Buckling gripper.” The Buckling gripper achieves adaptive gripping on rugged, uneven, and undulating surfaces typically found in the natural world. The key design principle of the Buckling gripper is inspired by a caterpillar's proleg that highly deforms depending on the shape of the contact surface. This key principle is applied to the gripper via flexural buckling. Normally, buckling is avoided in mechanical designs, but the buckling behavior of a flexure with an adequately selected length provides wide gripping range with a narrow range of force variation, which provides a sufficient number of contacts with even contact forces. As a result, the Buckling gripper achieves adaptive gripping on various surfaces, similar to a caterpillar. [ABSTRACT FROM PUBLISHER]

High-rise tasks such as cleaning, painting, inspection, and maintenance on walls of large buildings or other structures require robots with climbing and manipulating skills. Motivated by these potential applications and inspired by the climbing motion of inchworms, we have developed a biped wall-climbing robot—W-Climbot. Built with a modular approach, the robot consists of five joint modules connected in series and two suction modules mounted at the two ends. With this configuration and biped climbing mode, W-Climbot not only has superior mobility on smooth walls, but also has the function of attaching to and manipulating objects equivalent to a “mobile manipulator.” In this paper, we address several fundamental issues with this novel wall-climbing robot, including system development, analysis of suction force, basic climbing gaits, overcoming obstacles, and transiting among walls. A series of comprehensive and challenging experiments with the robot climbing on walls and performing a manipulation task have been conducted to demonstrate its superior climbing ability and manipulation function. The analytical and experimental results have shown that W-Climbot represents a significant advancement in the development of wall-climbing robots. [ABSTRACT FROM PUBLISHER]

Jumping may be considered to be quite a useful means of mobile robot locomotion, but acquiring a stable landing has been a difficult problem. This paper reports on the design, analysis, simulation and experiments of a mesoscale jumping robot that is capable of stable landing. A jumping mechanism inspired by jumping insects is introduced and an actuation scheme using only one shape memory alloy (SMA) spring is described. Experimental results show that a robot with a 17 gram weight and 13 cm diameter can jump forward as far as 1.2 times its body diameter and vertically as high as 1.5 times its body diameter. In addition, the robot is able to land in a stable manner and recover its initial posture after landing. [ABSTRACT FROM AUTHOR]

This paper is devoted to the active turn control of a free-swimming multilink dolphin-like robot, with emphasis on yaw and pitch controls. With full consideration of both mechanical configuration and propulsive principle of the robot consisting of a yaw joint and multiple pitch joints, a viable approach to perform yaw maneuvers via laterally directed biases is formed, providing an advantage in qualitative and quantitative assessment. Meanwhile, based on the feedback of the pitch angle measured by an onboard gyroscope, a closed-loop control strategy in dorsoventral motions is proposed to achieve agile and swift pitch maneuvers. More remarkably, two hybrid acrobatic stunts, i.e., frontflip and backflip, are first implemented on the physical robot. The latest results obtained demonstrate the effectiveness of the proposed methods. It is also confirmed that the dolphin robot achieves better performance for pitch maneuvers than it does for yaw maneuvers, agreeing well with the biological observations. [ABSTRACT FROM PUBLISHER]