Adaptive Swimming of Underwater Snake-like Robot in Different Underwater Environment

Hydrodynamic force is an important factor that affects the performance of underwater vehicle.Adapting to the current underwater environment by changing its shape is an important feature of underwater snake-like robots(USLR).An experiment was implemented to verify the swimming along the straight line of USLR.A simulation platform is also established for the analysis of the swimming of USLR.To figure out adaptive swimming of USLR to different underwater environments,the relationships between CPG parameters and maximum swimming speed have been discussed,and the switching between different swimming modes has been implemented.

Modeling and Control of Head of the Underwater Snake-like Robot Swimming

In order to solve oscillation of head of the underwater snake-like robot,the Central Pattern Generator( CPG)-based control scheme with head-controller was presented. The Kane dynamic model was constructed to be processed with a commercial package MotionGenesis Kane 5. 3,to which the proposed control scheme was applied. The relation between CPG parameters and orientation offset of head was investigated. The target orientation of head-controller was calculated through a convenient method. The advantage of this control scheme is that the head of the underwater snake-like robot remains in the forward direction during swimming. To prove the feasibility of the proposed methodology,two basic motion patterns,swimming along the straight line and swimming along the curved path,had been implemented in our simulation platform. The results showed that the simulation platform can imitate the swimming of the underwater snake-like robot and the head of the underwater snake-like robot remains in a fixed orientation directed towards the target. The oscillation of head's orientation is inhibited effectively.

Head Orientation Stability of Underwater Snake-Like Robot Swimming

In prior research,the orientation of head of the snake-like robot is changed according to the sinusoidal wave. To solve this problem,we propose Central Pattern Generator( CPG)-based control scheme with head-controller to stabilize the head of the underwater snake-like robot. The advantage of the CPG-based control scheme with head-controller is that the head of the underwater snake-like robot is direct to the target orientation during swimming. The relation between CPG parameters and orientation stability of head is discussed.The adaptation of the proposed method to environment changes is tested. The influences of CPG parameters and hydrodynamic forces on the orientation offset of head are investigated. The target orientation( the input of headcontroller) with an experimental optimization is calculated through a convenient method. To prove the feasibility of the proposed methodology,the different swimming modes have been implemented in our simulation platform.The results show that the oscillation of head's orientation is inhibited effectively,and the proposed method has strong adaptation to environment and CPG parameters changes.

Development and Control of Underwater Gliding Robots:A Review

As one of the most effective vehicles for ocean development and exploration,underwater gliding robots(UGRs)have the unique characteristics of low energy consumption and strong endurance.Moreover,by borrowing the motion principles of current underwater robots,a variety of novel UGRs have emerged with improving their maneuverability,concealment,and environmental friendliness,which significantly broadens the ocean applications.In this paper,we provide a comprehensive review of underwater gliding robots,including prototype design and their key technologies.From the perspective of motion characteristics,we categorize the underwater gliding robots in terms of traditional underwater gliders(UGs),hybrid-driven UGs,bio-inspired UGs,thermal UGs,and others.Correspondingly,their buoyancy driven system,dynamic and energy model,and motion control are concluded with detailed analysis.Finally,we have discussed the current critical issues and future development.This review offers valuable insight into the development of next-generation underwater robots well-suited for various oceanic applications,and aims to gain more attention of researchers and engineers to this growing field.

Wearable Robots for Human Underwater Movement Ability Enhancement:A Survey

Underwater robot technology has shown impressive results in applications such as underwater resource detection.For underwater applications that require extremely high flexibility,robots cannot replace skills that require human dexterity yet,and thus humans are often required to directly perform most underwater operations.Wearable robots(exoskeletons)have shown outstanding results in enhancing human movement on land.They are expected to have great potential to enhance human underwater movement.The purpose of this survey is to analyze the state-of-the-art of underwater exoskeletons for human enhancement,and the applications focused on movement assistance while excluding underwater robotic devices that help to keep the temperature and pressure in the range that people can withstand.This work discusses the challenges of existing exoskeletons for human underwater movement assistance,which mainly includes human underwater motion intention perception,underwater exoskeleton modeling and human-cooperative control.Future research should focus on developing novel wearable robotic structures for underwater motion assistance,exploiting advanced sensors and fusion algorithms for human underwater motion intention perception,building up a dynamic model of underwater exoskeletons and exploring human-in-theloop control for them.

Locomotion of Bioinspired Underwater Snake Robots Using Metaheuristic Algorithm

Snake Robots(SR)have been successfully deployed and proved to attain bio-inspired solutions owing to its capability to move in harsh environments,a characteristic not found in other kinds of robots(like wheeled or legged robots).Underwater Snake Robots(USR)establish a bioinspired solution in the domain of underwater robotics.It is a key challenge to increase the motion efficiency in underwater robots,with respect to forwarding speed,by enhancing the locomotion method.At the same time,energy efficiency is also considered as a crucial issue for long-term automation of the systems.In this aspect,the current research paper concentrates on the design of effectual Locomotion of Bioinspired Underwater Snake Robots using Metaheuristic Algorithm(LBIUSR-MA).The proposed LBIUSR-MA technique derives a bi-objective optimization problem to maximize the ForwardVelocity(FV)and minimize the Average Power Consumption(APC).LBIUSR-MA technique involves the design ofManta Ray Foraging Optimization(MRFO)technique and derives two objective functions to resolve the optimization issue.In addition to these,effective weighted sum technique is also used for the integration of two objective functions.Moreover,the objective functions are required to be assessed for varying gait variables so as to inspect the performance of locomotion.A detailed set of simulation analyses was conducted and the experimental results demonstrate that the developed LBIUSR-MA method achieved a low Average Power Consumption(APC)value of 80.52W underδvalue of 50.The proposed model accomplished the minimum PAC and maximum FV of USR in an effective manner.

Optical fiber based slide tactile sensor for underwater robots

In the underwater environment, many visual sensors don’t work, and many sensors which work well for robots working in space or on land can not be used underwater. Therefore, an optical fiber slide tactile sensor was designed based on the inner modulation mechanism of optical fibers. The principles and structure of the sensor are explained in detail. Its static and dynamic characteristics were analyzed theoretically and then simulated. A dynamic characteristic model was built and the simulation made using the GA based neural network. In order to improve sensor response, the recognition model of the sensor was designed based on the ‘inverse solution’ principle of neural networks, increasing the control precision and the sensitivity of the manipulator.

Underwater robots to safeguard Olympic Games in 2008

A small-sized autonomous underwater vehicle (AUV) independently developed and built by CAS researchers has been designated as an underwater

Environmental Adaptive Control of a Snake-like Robot With Variable Stiffness Actuators

This work investigates adaptive stiffness control and motion optimization of a snake-like robot with variable stiffness actuators. The robot can vary its stiffness by controlling magnetorheological fluid(MRF) around actuators. In order to improve the robot's physical stability in complex environments, this work proposes an adaptive stiffness control strategy. This strategy is also useful for the robot to avoid disturbing caused by emergency situations such as collisions. In addition, to obtain optimal stiffness and reduce energy consumption, both torques of actuators and stiffness of the MRF braker are considered and optimized by using an evolutionary optimization algorithm. Simulations and experiments are conducted to verify the proposed adaptive stiffness control and optimization methods for a variable stiffness snake-like robots.

A Survey of Underwater Multi-Robot Systems

As a cross-cutting field between ocean development and multi-robot system(MRS),the underwater multi-robot system(UMRS)has gained increasing attention from researchers and engineers in recent decades.In this paper,we present a comprehensive survey of cooperation issues,one of the key components of UMRS,from the perspective of the emergence of new functions.More specifically,we categorize the cooperation in terms of task-space,motion-space,measurement-space,as well as their combination.Further,we analyze the architecture of UMRS from three aspects,i.e.,the performance of the individual underwater robot,the new functions of underwater robots,and the technical approaches of MRS.To conclude,we have discussed related promising directions for future research.This survey provides valuable insight into the reasonable utilization of UMRS to attain diverse underwater tasks in complex ocean application scenarios.

An Integrated Hydrodynamics and Control Model of A Tethered Underwater Robot

An integrated hydrodynamics and control model to simulate tethered underwater robot system is proposed. The governing equation of the umbilical cable is based on a finite difference method, the hydrodynamic behaviors of the underwater robot are described by the six-degrees-of-freedom equations of motion for submarine simulations, and a controller based on the fuzzy sliding mode control(FSMC) algorithm is also incorporated. Fluid motion around the main body of moving robot with running control ducted propellers is governed by the Navier–Stokes equations and these nonlinear differential equations are solved numerically via computational fluid dynamics(CFD) technique. The hydrodynamics and control behaviors of the tethered underwater robot under certain designated trajectory and attitude control manipulation are then investigated based on the established hydrodynamics and control model. The results indicate that satisfactory control effect can be achieved and hydrodynamic behavior under the control operation can be observed with the model; much kinematic and dynamic information about tethered underwater robot system can be forecasted, including translational and angular motions of the robot, hydrodynamic loading on the robot, manipulation actions produced by the control propellers, the kinematic and dynamic behaviors of the umbilical cable. Since these hydrodynamic effects are fed into the proposed coupled model, the mutual hydrodynamic influences of different portions of the robot system as well as the hydrological factors of the undersea environment for the robot operation are incorporated in the model.

Dynamics model of underwater robot motion control in 6 degrees of freedom

In order to analyze underwater robot control system dynamics features, a system 6-DOF dynamics model was founded. Underwater robot linear and nonlinear hydrodynamics were analyzed by Taylor series, based on general motion equation. Special control system motion equation was deduced by cluster of inertial items and non-inertial items. For program convenience, motion equation matrix format was presented. Experimental principles of screw propellers, rudders and wings were discussed. Experimental data least-square curve fitting, interpolation and their corresponding traditional equation helped us to obtain the whole system dynamic response procedure. A series of simulation experiments show that the dynamics model is correct and reliable. The model can provide theory proof for analyzing underwater robot motion control system physics characters and provide a mathematic model for traditional control method.

Simulation Platform of Underwater Quadruped Walking Robot Based on MotionGenesis Kane 5.3 and Central Pattern Generator

It will still in lack of a simulation platform used to learn the walking of underwater quadruped walking robot. In order to alleviate this shortage,a simulation platform for the underwater quadruped walking robot based on Kane dynamic model and CPG-based controller is constructed. The Kane dynamic model of the underwater quadruped walking robot is processed with a commercial package MotionGenesis Kane 5. 3. The forces between the feet and ground are represented as a spring and damper. The relation between coefficients of spring and damper and stability of underwater quadruped walking robot in the stationary state is studied. The CPG-based controller consisted of Central Pattern Generator( CPG) and PD controller is presented,which can be used to control walking of the underwater quadruped walking robot. The relation between CPG parameters and walking speed of underwater quadruped walking robot is investigated. The relation between coefficients of spring and damper and walking speed of underwater quadruped walking robot is studied. The results show that the simulation platform can imitate the stable walking of the underwater quadruped walking robot.

Underwater robot local dry welding system

To satisfy the demand for good quality underwater welding and maintenance of nuclear power stations,a set of local dry automatic welding systems has been developed.These systems were based on an underwater robot that consisted of a special high-power underwater welding power supply,diving wire feeder,mini drain cap,welding robot,and special underwater welding torch.With a digital signal controller microprocessor as its core and combined with a dual inverter topology,the welding power supply was characterized by full-digital construction and multi-waveform flexible output.A compact diving wire feeding device was designed,based on the armature voltage negative feedback and high-frequency chopping pulse width modulation.This device yielded a high-efficiency seal of the driving motor with the help of dynamic and static sealing technology.To overcome the difficulty of local protection and deslagging in the welding area,a mini drain cap(with a duplexgas structure)based on the principle of the convergent nozzle was designed.The practical tests and the underwater welding experiments revealed that the underwater robotic local dry welding system is quite feasible.That is,the system could strike the arc stably and reliably in the shallow water environment,and formed beautiful welding seams.

The design of underwater hull-cleaning robot

The research on underwater ship-hull cleaning robot was conducted on the purpose of realizing the automation of cleaning underwater ship hull so that service life of ship will be prolonged and ship speed will raised. Moreover, fuel consumption and the work intensity of divers will be reduced. In this paper, the current situation and the latest technology in China and abroad were analyzed;meanwhile, the typical characteristics of the underwater cleaning robot were introduced. According to the work principle of the underwater cleaning robot, the emphasis was put on the analysis and study of permanent-magnetic absorption, magnetic wheel, airproof and anticorrosion, underwater cleaning equipment and control system. The robot is easy in rotation and simple in control.

Optical Fiber Type Slide Tactile Sensor Used for Underwater Robot

Because of the special underwater environment, many sensors used well in robots working in space or on the land can not be used in the underwater. So an optical fiber type slide tactile sensor is designed by the inner modulation mechanism of the intensity type optical fiber. The principle and structure of the sensor are introduced in detail. The static and dynamic characteristics are analyzed theoretically and experimentally. The dynamic characteristic model is built and the simulation is made by using genetic algorithm based on neural network. In order to use the sensor perfectly, the recognition model of the sensor is built on the basis of the principle of “inverse solution” using neural networks. The control precision and sensitivity of the manipulator are improved.

Design of Underwater Robot Lines Based on a Hybrid Automatic Optimization Strategy

在这份报纸，混合自动优化策略为设计被建议在水下机器人线。Isight 作为一个集成平台被介绍。这个平台的构造包括 UG6.0， GAMBIT2.4.6 和 FLUENT12.0 基于用户编程和几个商业软件。一个聪明的参数优化方法，粒子群优化，被合并到平台。为了验证策略，求婚了，模拟被进行在上在水下机器人为 5470 建模，它从 DTRC SUBOFF 工程发源。与自动优化平台，最小的抵抗作为优化目标被拿；是的湿表面区域限制条件；象设计变量的船身前半部，最大的身体半径和船体后部最小半径的长度。随 CFD 计算， RANS 方程和标准骚乱模型被用于直接数字的模拟。由模拟结果的分析，平台效率高，这被结束。通过平台，为线的设计的许多计划被产生，最佳的解决方案被完成。聪明的优化算法和数字模拟的联合保证一个全球最佳的答案并且改进寻找的答案的效率。

Control of Underwater Robot Attitude in Wave Based on Fuzzy Sliding Mode Method

When an underwater robot works with its manipulator,it is very critical to keep the position and attitude stable in wave. The modeling,numerical calculus of the rolling motion of a small open-frame underwater robot in wave was discussed. A sliding mode control(SMC) strategy with adaptive fuzzy reasoning is presented to change the rolling response process of the underwater robot by using the two lateral thrusters to reduce the rolling amplitude when the manipulators are working. The results comparing between the simulation and the numerical calculus has shown the effectiveness. There is few analogous research on underwater robot attitudes in wave. Some attempts are made here.

Modelling of thrust generated by oscillation caudal fin of underwater bionic robot

A simplified model of the thrust force is proposed based on a caudal fin oscillation of an underwater bionic robot. The caudal fin oscillation is generalized by cen- tral pattern generators （CPGs）. In this model, the drag coefficient and lift coefficient are the two critical parameters which are obtained by the digital particle image velocimetry （DPIV） and the force transducer experiment. Numerical simulation and physical experi- ments have been performed to verify this dynamic model.

Knowledge presentation by the MNSM-based controller for swimming motion of a snake-like robot

A MNSM( mirror neuron system mechanism)-based controller is developed to present the swimming rhythm of a snake-like robot in Cartesian space. From engineering viewpoint,the proposed controller is composed of a neuron for rhythm angle and two neurons for motion knowledge in XY plane. The given knowledge is a rhythm curve for swimming motion of a snake-like robot. Experimental results show that the proposed controller can present the knowledge of swimming rhythm,which represents the corresponding control law to drive the snake-like robot to swim with different speeds and turning motion. This work provides a novel method to present the knowledge for swimming motion of snake-like robots.