An Efficient Optimization Design Framework for Low-Resistance Shape of Bionic Amphibious Robot

To realize the low-resistance shape optimization design of amphibious robots,an efficient optimization design framework is proposed to improve the geometric deformation flexibility and optimization efficiency.In the proposed framework,the free-form deformation parametric model of the flat slender body is established and an analytical calculation method for the height constraints is derived.CFD method is introduced to carry out the high-precision resistance calculation and a constrained Kriging-based optimization method is built to improve the optimization efficiency by circularly infilling the new sample points which satisfying the constraints.Finally,the shape of an amphibious robot example is optimized to get the low-resistance shape and the results demonstrate that the presented optimization design framework has the advantages of simplicity,flexibility and high efficiency.

Development of amphibious biomimetic robots

Amphibious robots are becoming increasingly important for civilian,scientific,and environmental missions.They are widely used in disaster rescue,ecosystem monitoring,and entertainment.However,some have two different locomotion systems that need to be changed manually to fulfill both swimming in the water and moving on land,which may reduce their efficiency and reliability.Applying bioinspiration and biomimetics,many recently developed amphibious robots can undertake various tasks in complex amphibious environments with high mobility,flexibility,and energy efficiency.This review overviews the latest developments in amphibious robots,emphasizing biomimetic design concepts,backbone driving mechanisms,and typical applications.The performance indices of amphibious robots mimicking 13 different natural sources are compared,based on 10 different propulsion principles/modes,travel speed,working efficiency,maneuverability,and stability.Finally,the current challenges and perspectives of amphibious bio-inspired robots are discussed.This article summarizes the current types of amphibious robots and their movement and behavior solutions.The design concepts and operating mechanisms of amphibious robots reviewed here can be readily applied to other robotic studies.

Design and Mechanics of a Composite Wave-driven Soft Robotic Fin for Biomimetic Amphibious Robot

Bionic amphibious robots have important prospects in scientific, commercial, and military fields. Compared with traditional amphibious robots which use propellers/jets for aquatic medium and wheels/tracks for terrestrial medium, bionic propulsion method has great advantages in terms of manoeuvrability, efficiency, and reliability, because there is no need to switch between different propulsion systems. To explore the integrated driving technology of amphibious robot, a novel bio-inspired soft robotic fin for amphibious use is proposed in this paper. The bionic fin can swim underwater and walk on land by the same undulating motion. To balance the conflicting demands of flexibility underwater and rigidity on land, the undulating fin adopts a special combination of a membrane fin and a bending spring. A periodic longitudinal wave in horizontal direction has been found generating passively in dynamic analysis. To find the composite wave-driven mechanics, theoretical analysis is conducted based on the walking model and swimming model. A virtual prototype is built in ADAMS software to verify the walking mechanics. The simulation result reveals that the passive longitudinal wave is also periodical and the composite wave contributes to land walking. Finally, an amphibious robot prototype actuated by a pair of undulating fins has been developed. The experiments show that the robot can achieve multiple locomotion, including walking forward/backward, turning in place, swimming underwater, and crossing medium, thus giving evidence to the feasibility of the newly designed undulating fin for amphibious robot.

Locomotion Performance of the Amphibious Robot on Various Terrains and Underwater with Flexible Flipper Legs

Amphibious robots are attracting more and more attentions from researchers worldwide tbr their broad appllcanons m resource exploration, disaster rescue, and reconnaissance. Amphibious robot with transformable flipper-leg composite propul- sion mechanisms can adapt various terrestrial and water environments. In this paper, we explored the locomotion performance of a amphibious robot with flexible flipper legs on various terrains and underwater through dynamical simulation. The influence of the stiffness of the flipper legs on the locomotion performance in various environments was investigated comprehensively. The results indicate that the locomotion with flexible flipper legs is very stable, and the stiffness of the flipper legs has a great impact on the locomotion performance. The verification experiments demonstrate the accuracy of the simulation results. The study facilitates the design of the amphibious robot and indicates that the passively transformable flipper-leg mechanisms also enable amphibious robot to conquer various complex terrestrial environments.

Initial Development of a Novel Amphibious Robot with Transformable Fin-Leg Composite Propulsion Mechanisms

Amphibious robots are very attractive for their broad applications in resource exploration, disaster rescue, and recon- naissance. However, it is very challenging to develop the robots for their complex, amphibious working environments. In the complex amphibious environment, amphibious robots should possess multi-capabilities to walk on rough ground, maneuver underwater, and pass through transitional zones such as sandy and muddy terrain. These capabilities require a high-performance propulsion mechanism for the robots. To tackle a complex task, a novel amphibious robot （AmphiHex-I） with,transformable fin-leg composite propulsion mechanisms is developed. With the fin-leg composite propulsions, AmphiHex-I can walk on rough and soft substrates and swim in water with many maneuvers. This paper presents the structural design of the transformable fin-leg propulsion mechanism and its driving module. A hybrid model is used to explore the dynamics between the trans- formable legs and transitional environment such as granular medium. The locomotion performances of legs with various ellip- tical shapes are analyzed, which is verified by the coincidence between the model predictions and the simulation results. Further, an orthogonal experiment is conducted to study the locomotion performance of a two-legged platform walking with an asyn- chronous gait in the sandy and muddy terrain. Finally, initial experiments of AmphiHex-I walking on various lands and swimming in water are implemented. These results verify that the transformable fin-leg mechanisms enable the amphibious robot to pass through a complex, amphibious working environment.

Development of an Amphibious Turtle-Inspired Spherical Mother Robot

Robots play an important role in underwater monitoring and recovery operations, such as pollution detection, submarine sampling and data collection, video mapping, and object recovery in dangerous places. However, regular-sized robots may not be suitable for applications in some restricted underwater environments. Accordingly, in previous research we designed several novel types of bio-inspired microrobots using Ionic Polymer Metal Composite （IPMC） and Shape Memory Alloy （SMA） ac- tuators. These microrobots possess some attributes of compact structure, multi-functionality, flexibility, and precise positioning. However, they lack the attributes of long endurance, stable high speed, and large load capacity necessary for real-world appli- cations. To overcome these disadvantages, we proposed a mother-son robot system, composed of several microrobots as sons and a newly designed amphibious spherical robot as the mother. Inspired by amphibious turtles, the mother robot was designed with a spherical body and four legs with two Degrees of Freedom （DOF）. It is actuated by four vectored water-jet propellers and ten servomotors, and it is capable of walking on land and cruising underwater. We analysed the mother robot＇s walking and underwater cruising mechanisms, constructed a prototype, and carried out a series of experiments to evaluate its amphibious motions. Good motion performance was observed in the experiments.

A Fuzzy PID Algorithm for a Novel Miniature Spherical Robots with Three-dimensional Underwater Motion Control

We proposed and developed a small bionic amphibious spherical robot system for tasks such as coastal environment monitoring and offshore autonomous search and rescue.Our third-generation bionic small amphibious spherical robots have many disadvantages,such as the lack of maneuverability and a small operating range.It is difficult to accomplish underwater autonomous motion control with these robots.Therefore,we proposed a fourth-generation amphibious spherical robot.However,the amphibious spherical robot developed in this project has a small and compact design,with limited sensors and external sensing options.This means that the robot has weak external information collection capabilities.We need to make the real time operation of the robot's underwater motion control system more reliable.In this paper,we mainly used a fuzzy Proportional-Integral-Derivative(PID)control algorithm to design an underwater motion control system for a novel robot.Moreover,we compared PID with fuzzy PID control methods by carrying out experiments on heading and turning bow motions to verify that the fuzzy PID is more robust and exhibits good dynamic performance.We also carried out experiments on the three-dimensional(3D)motion control to validate the design of the underwater motion control system.

Dynamic Modeling and Hybrid Fireworks Algorithm-Based Path Planning of an Amphibious Robot

The task of path planning in amphibious environments requires additional consideration due to the complexity of the amphibious environments.This paper presents a path planning method for an amphibious robot named\AmphiRobot"with its dynamic constraints considered.First,an explicit dynamic model using Kane's method is presented.The hydrodynamic parameters are obtained through computational°uid dynamics simulations.Furthermore,a path planning method based on a hybrid¯reworks algorithm is proposed,combining the¯reworks algorithm and bare bones¯reworks algorithm,aiming at the amphibious robot's characteristics of multiple motion modes and working environments.The initially planned path is then smoothed using Dubins path under constraints determined by the dynamic model.Simulation reveals that the performance of the hybrid¯reworks algorithm approach is better than the¯reworks algorithm and bare bones¯reworks algorithm is applied separately in the amphibious environment scenarios.

Study on Decentralization of Spherical Amphibious Multi-robot Control System Based on Smart Contract and Blockchain

With the development of intelligent bionic robots and the improvement of military application,a single robot cannot meet the requirements of the tasks of the current era.The more complex tasks require not only that the robot be able to pass through the field barriers and the amphibious environment,but also that the robot be able to collaborate in a multi-robot system.Consequently,research on the multi-robot control system of spherical amphibious robots is very important.Presently,the main research on amphibious robots is to improve the functions of a single robot,in the absence of the study of the multi-robot control system.Existing systems primarily use a centralized control methodology.Although the transfer of central node can be achieved,there is still a problem of Byzantine fault tolerance in military applications,that is,when the amphibious multi-robot system is invaded by the enemy.The central node may not only fail to accomplish the task,but also lose control of other robots,with severe consequences.To solve the above problems,this paper proposed a decentralized method of spherical amphibious multi-robot control system based on blockchain technology.First,the point-to-point information network based on long range radio technology of low power wide area network was set up,we designed the blockchain system for embedded application environment and the decentralized hardware and software architecture of multi-robot control system.On this basis,the consensus plugin,smart contract and decentralized multi-robot control algorithm were designed to achieve decentralization.The experimental results of consensus of spherical amphibious multi-robot showed the effectiveness of the decentralization.

Design, Implementation and Control of an Amphibious Spherical Robot

We proposed and implemented a leg-vector water-jet actuated spherical robot and an underwater adaptive motion control system so that the proposed robot could perform exploration tasks in complex environments.Our aim was to improve the kinematic performance of spherical robots.We developed mechanical and dynamic models so that we could analyze the motions of the robot on land and in water.The robot was equipped with an Inertial Measurement Unit(IMU)that provided inclination and motion information.We designed three types of walking gait for the robot,with different stabilities and speeds.Furthermore,we proposed an online adjustment mechanism to adjust the gaits so that the robot could climb up slopes in a stable manner.As the system function changed continuously as the robot moved underwater,we implemented an online motion recognition system with a forgetting factor least squares algorithm.We proposed a generalized prediction control algorithm to achieve robust underwater motion control.To ensure real-time performance and reduce power consumption,the robot motion control system was implemented on a Zynq-7000 System-on-Chip(SoC).Our experimental results show that the robot’s motion remains stable at different speeds in a variety of amphibious environments,which meets the requirements for applications in a range of terrains.

A Hybrid Territorial Aquatic Bionic Soft Robot with Controllable Transition Capability

In this paper,a bionic mantis shrimp amphibious soft robot based on a dielectric elastomer is proposed to realize highly adaptive underwater multimodal motion.Under the action of an independent actuator,it is not only able to complete forward/backwards motion on land but also has the ability of cyclically controllable transition motion from land to water surface,from water surface to water bottom and from water bottom to land.The fastest speed of the soft robot on land is 170 mm/s,and it can crawl while carrying up to 4.6 times its own weight.The maximum speeds on the water surface and the water bottom are 30 mm/s and 14.4 mm/s,respectively.Furthermore,the soft robot can climb from the water bottom with a 9°slope transition to land.Compared with other similar soft robots,this soft robot has outstanding advantages,such as agile speed,large load-carrying capacity,strong body flexibility,multiple motion modes and strong underwater adaptability.Finally,nonlinear motion models of land crawling and water swimming are proposed to improve the environmental adaptability under multiple modalities,and the correctness of the theoretical model is verified by experiments.

A Novel Design of an Aquatic Walking Robot Having Webbed Feet

Inspired by the movement of duck that is able to move on land and water utilizing its webbed feet, a novel design of an amphibious robot has been presented in this paper. In contrary, the orthodox design of amphibious robot utilizes the tracks or wheels on land and switches to the propeller to move in water. The proposed design employs same propulsion system as webbed feet to move on land and water. After studying the movement of the duck underwater, a conclusion has been drawn that it is swimming in the water by moving its webbed feet back and forth to generate force to push its body forward. Recreating this phenomenon of duck movement, hybrid robot locomotion has been designed and developed which is able to walk, swim and climb steps using the same propulsion system. Moreover, webbed feet would be able to walk efficiently on muddy, icy or sandy terrain due to uneven distribution of robot weight on the feet. To be able to justify the feasibility of the design, simulations are being carried out using SimulationXpress of the SOLIDWORKS software.