Adaptive Sensor-Fault Tolerant Control of Unmanned Underwater Vehicles With Input Saturation

This paper investigates the tracking control problem for unmanned underwater vehicles(UUVs)systems with sensor faults,input saturation,and external disturbance caused by waves and ocean currents.An active sensor fault-tolerant control scheme is proposed.First,the developed method only requires the inertia matrix of the UUV,without other dynamic information,and can handle both additive and multiplicative sensor faults.Subsequently,an adaptive fault-tolerant controller is designed to achieve asymptotic tracking control of the UUV by employing robust integral of the sign of error feedback method.It is shown that the effect of sensor faults is online estimated and compensated by an adaptive estimator.With the proposed controller,the tracking error and estimation error can asymptotically converge to zero.Finally,simulation results are performed to demonstrate the effectiveness of the proposed method.

Application of A* Algorithm for Real-time Path Re-planning of an Unmanned Surface Vehicle Avoiding Underwater Obstacles

This paper describes path re-planning techniques and underwater obstacle avoidance for unmanned surface vehicle(USV) based on multi-beam forward looking sonar(FLS). Near-optimal paths in static and dynamic environments with underwater obstacles are computed using a numerical solution procedure based on an A* algorithm. The USV is modeled with a circular shape in 2 degrees of freedom(surge and yaw). In this paper, two-dimensional(2-D) underwater obstacle avoidance and the robust real-time path re-planning technique for actual USV using multi-beam FLS are developed. Our real-time path re-planning algorithm has been tested to regenerate the optimal path for several updated frames in the field of view of the sonar with a proper update frequency of the FLS. The performance of the proposed method was verified through simulations, and sea experiments. For simulations, the USV model can avoid both a single stationary obstacle, multiple stationary obstacles and moving obstacles with the near-optimal trajectory that are performed both in the vehicle and the world reference frame. For sea experiments, the proposed method for an underwater obstacle avoidance system is implemented with a USV test platform. The actual USV is automatically controlled and succeeded in its real-time avoidance against the stationary undersea obstacle in the field of view of the FLS together with the Global Positioning System(GPS) of the USV.

Technology Development of Unmanned Underwater Vehicles (UUVs)

In recent years, the weapon systems have been changing drastically because of the advancement of science technology and the change of military concept of combat. There is an unmanned system at the center of all those changes. Especially, in case of maritime environment, as the center stage of combat has changed from ocean to coastal areas, it is difficult for the existing naval forces to effectively operate in shallow waters. Therefore, unmanned underwater vehicles (UUVs) are being required at an increasing pace. In this paper, we analyze the characteristics of already developed UUVs, which are the key unmanned system of the marine battlefield environment in the future. Through the analysis of development cases and the investigation of the essential technologies, the critical design issues of UUVs are elaborated. We also suggest the future directions of the UUV technologies based on the case analysis.

Application of unmanned underwater vehicles in polar research

The importance of polar ice as vital components of the global ocean-climate system is widely recognized.In this paper,we demonstrate the importance and urgency of polar research,describe the primary characteristics of sea ice and ice shelves,and outline the current status and difficulties associated with sub-ice research.We highlight the importance of Unmanned Underwater Vehicles(UUVs)as important tools for oceanographic research.We present recent progress in UUV deployment in sub-ice research in the Arctic and the Antarctic,and review the latest international developments in UUV structure,navigation,payload,and field operation.Moreover,Chinese polar UUVs and their deployments in the polar regions are presented in detail.Key technologies and solutions regarding polar application of UUVs(e.g.,sub-ice navigation and positioning,energy supply and data transmission,and sub-ice guidance and recovery)are discussed.Given the current worldwide attention on polar science,the potential future directions of UUV-related polar research(e.g.,observations under Antarctic ice shelves,long-range surveys beneath Arctic sea ice and application of intelligent technology)are discussed.

Using Unmanned Underwater Vehicles as Research Platforms in Coastal Ocean Studies

The advantages of using unmanned underwater vehicles in coastal ocean studies are emphasized. Two types of representative vehicles, remotely operated vehicle (ROV) and autonomous underwater vehicle (AUV) from University of South Florida, are discussed. Two individual modular sensor packages designed and tested for these platforms and field measurement results are also presented. The bottom classification and albedo package, BCAP, provides fast and accurate estimates of bottom albedos, along with other parameters such as in-water remote sensing reflectance. The real-time ocean bottom optical topographer, ROBOT, reveals high-resolution 3-dimentional bottom topography for target identification. Field data and results from recent Coastal Benthic Optical Properties field campaign, 1999 and 2000, are presented. Advantages and limitations of these vehicles and applications of modular sensor packages are compared and discussed.

Experimental Study of a Modified Command Governor Adaptive Controller for Depth Control of an Unmanned Underwater Vehicle

Command governor–based adaptive control(CGAC)is a recent control strategy that has been explored as a possible candidate for the challenging task of precise maneuvering of unmanned underwater vehicles(UUVs)with parameter variations.CGAC is derived from standard model reference adaptive control(MRAC)by adding a command governor that guarantees acceptable transient performance without compromising stability and a command filter that improves the robustness against noise and time delay.Although simulation and experimental studies have shown substantial overall performance improvements of CGAC over MRAC for UUVs,it has also shown that the command filter leads to a marked reduction in initial tracking performance of CGAC.As a solution,this paper proposes the replacement of the command filter by a weight filter to improve the initial tracking performance without compromising robustness and the addition of a closed-loop state predictor to further improve the overall tracking performance.The new modified CGAC(M-CGAC)has been experimentally validated and the results indicate that it successfully mitigates the initial tracking performance reduction,significantly improves the overall tracking performance,uses less control force,and increases the robustness to noise and time delay.Thus,M-CGAC is a viable adaptive control algorithm for current and future UUV applications.

Multiple Unmanned Underwater Vehicles Consensus Control with Unmeasurable Velocity Information and Environmental Disturbances Under Switching Directed Topologies

A consensus algorithm proposed in the paper is applied to tackle remarkable problems of unmeasurable velocities,the environmental disturbances, and the limited communication environment for the multiple unmanned underwater vehicles(multi-UUVs). Firstly, for a complex nonlinear and coupled model of the unmanned underwater vehicle(UUV), a technique of feedback linearization is developed to transform the nonlinear UUV model into a secondorder integral UUV model. Secondly, to address the problem of the unavailable velocity information and environmental disturbances for the multi-UUVs system, we design a distributed extended state observer(DESO) to estimate the unmeasurable velocities and environmental disturbances using the relative position information. Finally,we propose a protocol based on the estimation information from the DESO and demonstrate that the multi-UUVs system with the switching directed topologies under the protocol can reach consensus asymptotically. The theoretical result proposed in the literature is verified by one numerical example.

Submarine Hunter: Efficient and Secure Multi-Type Unmanned Vehicles

Utilizing artificial intelligence(AI)to protect smart coastal cities has become a novel vision for scientific and industrial institutions.One of these AI technologies is using efficient and secure multi-environment Unmanned Vehicles(UVs)for anti-submarine attacks.This study’s contribution is the early detection of a submarine assault employing hybrid environment UVs that are controlled using swarm optimization and secure the information in between UVs using a decentralized cybersecurity strategy.The Dragonfly Algorithm is used for the orientation and clustering of the UVs in the optimization approach,and the Re-fragmentation strategy is used in the Network layer of the TCP/IP protocol as a cybersecurity solution.The research’s noteworthy findings demonstrate UVs’logistical capability to promptly detect the target and address the problem while securely keeping the drone’s geographical information.The results suggest that detecting the submarine early increases the likelihood of averting a collision.The dragonfly strategy of sensing the position of the submersible and aggregating around it demonstrates the reliability of swarm intelligence in increasing access efficiency.Securing communication between Unmanned Aerial Vehicles(UAVs)improves the level of secrecy necessary for the task.The swarm navigation is based on a peer-to-peer system,which allows each UAV to access information from its peers.This,in turn,helps the UAVs to determine the best route to take and to avoid collisions with other UAVs.The dragonfly strategy also increases the speed of the mission by minimizing the time spent finding the target.

Attitude Stabilization of Unmanned Underwater Vehicle During Payloads Release

Large unmanned underwater vehicles can carry big payloads for varied missions and it is desirable for them to possess an upright orientation during payload release.Their attitude can hardly be maintained during and after the phase of payload release.Releasing a payload from the vehicle induces uncertainties not only in rigid-body parameters,e.g,the moment of inertia tensor due to the varying distribution of the masses on board the vehicle,but also in the hydrodynamic derivatives due to the vehicle’s varying geometric profile.A nonlinear attitude stabilizer that is robust to these time-varying model uncertainties is proposed in this paper.Stability is guaranteed via Lyapunov stability theory.The simulation results verify the effectiveness of the proposed approach.

Hydrodynamic Modeling with Grey-Box Method of A Foil-Like Underwater Vehicle

In this study, a dynamic modeling method for foil-like underwater vehicles is introduced and experimentally verified in different sea tests of the Hadal ARV. The dumping force of a foil-like underwater vehicle is sensitive to swing motion. Some foil-like underwater vehicles swing periodically when performing a free-fall dive task in experiments. Models using conventional modeling methods yield solutions with asymptotic stability, which cannot simulate the self-sustained swing motion. By improving the ridge regression optimization algorithm, a grey-box modeling method based on 378 viscous drag coefficients using the Taylor series expansion is proposed in this study. The method is optimized for over-fitting and convergence problems caused by large parameter matrices. Instead of the PMM test data, the unsteady computational fluid dynamics calculation results are used in modeling. The obtained model can better simulate the swing motion of the underwater vehicle. Simulation and experimental results show a good consistency in free-fall tests during sea trials, as well as a prediction of the dive speed in the swing state.

A new robust fuzzy method for unmanned flying vehicle control

A new general robust fuzzy approach was presented to control the position and the attitude of unmanned flying vehicles(UFVs). Control of these vehicles was challenging due to their nonlinear underactuated behaviors. The proposed control system combined great advantages of generalized indirect adaptive sliding mode control(IASMC) and fuzzy control for the UFVs. An on-line adaptive tuning algorithm based on Lyapunov function and Barbalat lemma was designed, thus the stability of the system can be guaranteed. The chattering phenomenon in the sliding mode control was reduced and the steady error was also alleviated. The numerical results, for an underactuated quadcopter and a high speed underwater vehicle as case studies, indicate that the presented adaptive design of fuzzy sliding mode controller performs robustly in the presence of sensor noise and external disturbances. In addition, online unknown parameter estimation of the UFVs, such as ground effect and planing force especially in the cases with the Gaussian sensor noise with zero mean and standard deviation of 0.5 m and 0.1 rad and external disturbances with amplitude of 0.1 m/s2 and frequency of 0.2 Hz, is one of the advantages of this method. These estimated parameters are then used in the controller to improve the trajectory tracking performance.

A hybrid tracking control strategy for an unmanned underwater vehicle aided with bioinspired neural dynamics

Tracking control has been a vital research topic in robotics.This paper presents a novel hybrid control strategy for an unmanned underwater vehicle(UUV)based on a bio-inspired neural dynamics model.An enhanced backstepping kinematic control strategy is first developed to avoid sharp velocity jumps and provides smooth velocity commands relative to conventional methods.Then,a novel sliding mode control is proposed,which is capable of providing smooth and continuous torque commands free from chattering.In comparative studies,the proposed combined hybrid control strategy has ensured control signal smoothness,which is critical in real‐world applications,especially for a UUV that needs to operate in complex underwater environments.

基于BP神经网络的非线性流域UUV动态回收过程预测

针对水下无人自主航行器(UUV)回收过程中流域存在非线性干扰问题,提出了一种基于BP神经网络优化UUV回收路径的闭环控制方法。采用计算流体力学(CFD)方法模拟UUV相对于潜艇以不同路径进行回收的水动力系数,将数值模拟结果作为训练BP神经网络的初始数据,利用拉丁超立方法对非线性流域的位置随机采样,采用神经网络输出UUV在采样处的水动力系数,实现非线性流域内UUV动态回收过程的水动力系数预测。结果表明:通过均方根检验神经网络预测水动力系数误差均在10%范围内。将神经网络预测结果与UUV纵向操纵性方程结合,对比回收速度和操舵间隔与理论回收轨迹的误差,优化UUV动态回收路径的闭环控制方案。

水下无人航行器高速航行下的运动特性及仿真控制研究

水下无人航行器具有水下活动范围大、机动性好优点,主要用于大范围地形地貌勘探,水下高速长航程航行时,水下航行器运动特性和姿态控制是研究重点。本文建立水下航行器垂直面航行运动模型,分析高速航行下的运动特性。为保证高速航行高效稳定,提出PID方法控制纵倾和滑模方法控制深度的组合控制策略。通过仿真试验,开展高速航行运动仿真研究。研究结果表明,在高速航行下,水下航行器会产生一定纵倾,且随着航速增加,纵倾影响会越大,高速状态放大了水下航行器外形上下轻微不对称的特性,诱导产生的垂向水动力及力矩增大,进而引起纵倾;在高速航行条件下,水下航行器能稳定保持定深度长距离航行,控制策略具有很好的适用性。

水下航行体极限大机动流动分离大涡模拟研究

针对大机动极限工况下水下航行体流动分离带来的机动性不足问题,本文以Suboff标模为研究对象,采用大涡模拟数值计算方法开展大机动工况下水下航行体的流体动力性能评估,并完成水下航行体尾部及舵面流动分离涡旋结构的精细捕捉。本文研究成果可为后续极限机动工况下水下航行体流动控制提供技术支撑。

近海复杂环境下UUV动态路径规划方法研究

为解决近海环境下水下无人航行器(unmanned underwater vehicle,UUV)的动态路径规划问题,本文提出一种结合全局和局部动态路径规划的算法。首先,本文提出一种基于自适应目标引导的快速拓展随机树算法,以增加随机树生长的方向性,并通过转向和重选策略减少无效拓展加快算法的收敛速度。接着,获得全局路径之后使用自适应子节点选取策略获取动态窗口法的子目标点,将复杂的全局动态任务规划分解为多个简单的动态路劲规划,从而防止动态窗口法陷入局部极小值。最后,通过UUV出港任务仿真实验验证了算法的有效性和实用性。

无人航行器声隐身性能提升研究

针对小几何尺度的无人航行器(Unmanned Underwater Vehicle,UUV)中减振技术的应用问题,建立尺度较小的SUBOFF无人航行器有限元模型。分析其在典型激励下的声振特性,探讨阻振、吸振技术在UUV上的应用,并且基于声学黑洞结构设计UUV舱段,分析其减振效果。研究结果表明:无人航行器结构振动和辐射噪声的峰值频率与整体和局部结构的模态频率关系较大。在推进电机基座、推力轴承基座等结构上应用阻振质量和动力吸振器可有效减小艇体振动,吸振器质量增加可改善吸振效果。设计声学黑洞(Acoustic Black Hole,ABH)舱段并应用于艇体的中部均匀部分,可有效减小结构振动由激励源向船艏的传递,体现该方案的减振效果。

水下无人系统通用质量特性工程技术发展与挑战

通用质量特性工程技术是保障水下无人系统在复杂海洋环境下的任务出动能力、执行能力和生存能力的重要技术之一。回顾了水下无人系统的发展现状,从复杂环境适应性、智能化特征可靠性和集群化特征可靠性3个角度分析了水下无人系统通用质量特性技术的发展方向和面临的主要挑战,为我国水下无人系统装备通用质量特性工程技术发展提供了一条参考思路。

海水对UUV WPT系统的影响及耦合机构的补偿研究

针对水下无人航行器(UUV)无线电能传输(WPT)系统的效率和稳定性问题,建立了水下WPT等效电路,并对其工作原理进行了数学推导和分析。以此为基础研究了海水环境对WPT电路性能的影响机理,推导出了WPT系统在海水中的传输功率及效率模型。由于在海浪和海流等水下外界干扰下电能传输机构的收/发端均会产生偏移,从而影响系统电能传输的稳定性和效率。为减小影响,分析了4种典型拓扑补偿电路结构,并给出了最优补偿电路选取原则。最后,在MATLAB平台进行验证,结果验证了数学推导的正确性以及补偿电路设计的有效性。研究结果可为类似水下无线供电系统的设计提供借鉴。

无人作战平台导航装备分析及趋势

面向国内外目前大力发展水下无人潜航器、水面无人艇的背景,通过分析国外无人潜航器、水面无人艇的使命任务、技术状态和分级标准,提出国内无人潜航器、水面无人艇的分级设想和导航能力需求。结合典型无人平台导航装备配置情况进一步分析,构建国内无人作战平台导航装备配置谱系,为我国海军无人作战平台导航装备发展形成谱系化、阶梯化导航能力具有启示意义。