一种水下机器人传感器故障诊断与容错控制方法

采用自适应滤波器ＦＩＲ 对水下机器人进行在线自适应建模,并利用ＬＭＳ算法来调节滤波器的权系数．通过对滤波器权系数和误差信号平方的分析,实时检测出传感器的故障,并应用ＦＩＲ 滤波器输出替代故障传感器信号,实现传感器故障情形下水下机器人容错控制．应用该方法对Ｏｕｔｌａｎｄ１０００水下机器人传感器的故障进行检测和容错,实验结果表明所提故障检测方法准确可靠,具有较好的容错效果．

     

基于降阶卡尔曼滤波器的水下机器人滑模容错控制

针对水下机器人执行器时变、非线性故障,提出一种基于降阶卡尔曼滤波器的故障估计和滑模容错控制方法.用降阶卡尔曼滤波器估计水下机器人故障解耦子系统的状态,受故障的影响,子系统状态可测.由估计的状态和测量的状态可进一步得到水下机器人执行器的故障信息.滑模容错控制器根据所估计的执行器故障调整控制器的输出以实现容错控制.仿真结果验证了所提出的故障辨识与容错控制算法的有效性.     

旋翼飞行机器人故障诊断与容错控制技术综述

对故障诊断和容错技术的发展过程进行了简要概述，以旋翼飞行机器人为研究对象，在分析了旋翼飞行机器人故障诊断与容错控制特点的基础上，介绍了当前国内外在该领域的研究进展和主要方法．最后，总结了该领域待解决的难点问题，并指出了该研究领域的发展趋势．     

自主式水下机器人滑模容错自动化控制方法

针对因水下机器人工作环境噪声影响较大、难以提取故障特征点,导致控制精准度较低的问题,该文提出一种滑模容错自动化控制方法。建立机器人五自由度空间方程以及故障执行器的动力学方程,计算机器人每个关键滑模点的不确定性因素变化矢量,推导得到机器人的离散故障状态方程。根据机器人在期望状态下的滑模特性,将故障状态参数代入后,识别定位到故障点,提取机器人线性反馈的控制规律,设定机器人在滑模容错控制函数中的双曲正切函数,计算产生滑模动态的控制输入值,实现自动化控制。实验结果证明,所提方法在第25 s处即发现故障,输出信号幅值稳定在-28 Hz～28 Hz之间,具有良好的自动化控制能力。     

水下机器人推力器容错控制技术的研究

为保证自主式水下机器人在高压、可见度差的未知海洋环境下顺利完成作业任务,必然要求水下机器人具有容错控制能力．本文主要以哈尔滨工程大学研制的“智水Ⅲ”型水下机器人为对象,探讨水下机器人推力器容错控制技术．文中先给出在正常情况下水下机器人的解耦控制器及推力分配,然后给出了在推力器出现故障时的容错控制策略．仿真结果表明,该控制器及容错控制策略都能达到很好的控制精度．     

基于ODDD水下机器人故障诊断方法

近年来数据挖掘技术的快速发展使得利用水下机器人作业过程中积累的大量数据进行故障诊断成为可能;基于数据挖掘的故障诊断技术能够从数据中获取潜在的诊断知识;针对水下机器人推进器系统数据特征,提出一种基于聚类和距离的离群点检测方法(outlier detection based on dbscan and distance,ODDD);首先,对数据进行粗聚类,然后采用剪枝规则进行离群点检测,来实现故障诊断;仿真实验结果表明算法能够实现水下机器人快速有效的故障检测.     

水下机器人传感器容错控制技术的研究

在分析水下机器人的解耦控制器及传感器系统的基础上,探讨了传感器出现故障时采用以滑模观测器输出代替传感器输出的容错控制（又叫取代控制）策略．对于传感器出现的无法修复性故障,这种策略最小化了其带给机器人的损伤．对于传感器出现的跳变故障,则在跳变故障的时间内采用取代控制．仿真结果表明了方法的有效性．     

水下机器人多传感器并发故障检测方法

针对水下机器人多传感器并发故障检测问题,提出了一种小波分析和神经网络相结合的故障特征提取方法,将小波多分辨率分解后的细节系数进行小波重构,对重构后的细节系数进行融合得到整体高频细节信息量作为一类故障特征值;同时,基于改进的Elman 网络建立水下机器人的全阶状态观测器模型,模型输出与传感器测量值之间的差值作为另一类故障特征值．为进行水下机器人多传感器并发故障定位,提出了一种模糊加权属性信息融合方法,将两类故障特征值的重要度与可信度进行模糊合成转换,基于转换结果将各故障特征值加权融合,进行水下机器人多传感器并发故障定位．水下机器人实验样机的水池实验结果验证了本文所提方法的可行性和有效性．     

水下机器人的神经网络自适应控制

研究了水下机器人神经网络直接自适应控制方法,采用Lyapunov稳定性理论,证明了存在有界外界干扰和有界神经网络逼近误差条件下,水下机器人控制系统的跟踪误差一致稳定有界.为了进一步验证该水控制方法的正确性和稳定性,利用水下机器人实验平台进行了动力定位实验、单自由度跟踪实验和水平面跟踪实验等验证实验.     

水下机器人传感器故障诊断

在分析水下机器人传感器故障形式的基础上,对传感器可能出现的三种故障形式分别给出了相应的诊断方法,即通过传感器长时间采集不到数据来诊断传感器信息保持不变的故障,线性平滑滤波解决传感器输出振荡,小波变换检测传感器信息的突变．海中试验验证了本方法的可行性．     

Thruster fault diagnosis and accommodation for open-frame underwater vehicles

This paper introduces a novel thruster fault diagnosis and accommodation system (FDAS) for open-frame underwater vehicles. Basically, the FDAS is a control allocator, but this primary function is enhanced with the ability of automatic thruster fault detection and accommodation. The proposed FDAS consists of two subsystems: a fault diagnosis subsystem (FDS) and a fault accommodation subsystem (FAS). The FDS uses fault detector units (FDUs), associated with each thruster, to monitor their state. Robust and reliable FDUs are based on integration of self-organising maps and fuzzy logic clustering methods. These units are able to detect internal and external faulty states of thrusters. The FAS uses information provided by the FDS to accommodate faults and perform an appropriate control reallocation. A control energy cost function is used as the optimisation criteria. The FAS uses weighted pseudo-inverse to find the solution of the control allocation problem, which minimise this criteria. Two approximations (truncation or scaling) can be used to ensure feasibility of the solution. The proposed FDS is evaluated with data obtained during test trials. The feasible region concept, related with the problem of thruster velocity saturation, is developed in order to provide geometrical interpretation of the control allocation problem. The proposed FDAS is implemented as a Simulink model (ROV simulator), in order to evaluate its performance in different faulty situations.     

Depth control of autonomous underwater vehicles using indirect robust control method

In this article, we propose a robust depth control design scheme for autonomous underwater vehicles (AUVs) in the presence of hydrodynamic parameter uncertainties and disturbances. The controller is designed via a new indirect robust control method that handles the uncertainties by formulating the uncertainty bounds into the cost functional and then transforming the robust control problem into an equivalent optimal control problem. Both robust asymptotic stability and optimality can be achieved and proved with this new formulation. The θ-D method is utilised to solve the resultant nonlinear optimal control problem such that an approximate closed-form feedback controller can be obtained and thus is easy to implement onboard without intensive computation load. Simulation results demonstrate that robust depth control is accomplished under the system parameter uncertainties and disturbances with small control fin deflection requirement.     

Implicit fault-tolerant control: application to induction motors

In this paper we propose an innovative way of dealing with the design of fault-tolerant control systems. We show how the nonlinear output regulation theory can be successfully adopted in order to design a regulator able to offset the effect of all possible faults which can occur and, in doing so, also to detect and isolate the occurred fault. The regulator is designed by embedding the (possible nonlinear) internal model of the fault. This idea is applied to the design of a fault-tolerant controller for induction motors in presence of both rotor and stator mechanical faults.     

Bibliographical review on reconfigurable fault-tolerant control systems

In this paper, a bibliographical review on reconfigurable (active) fault-tolerant control systems (FTCS) is presented. The existing approaches to fault detection and diagnosis (FDD) and fault-tolerant control (FTC) in a general framework of active fault-tolerant control systems (AFTCS) are considered and classified according to different criteria such as design methodologies and applications. A comparison of different approaches is briefly carried out. Focuses in the field on the current research are also addressed with emphasis on the practical application of the techniques. In total, 376 references in the open literature, dating back to 1971, are compiled to provide an overall picture of historical, current, and future developments in this area.     

Model predictive and non-cooperative dynamic game fault recovery control strategies for a network of unmanned underwater vehicles

In this paper, the problem of control and fault recovery for a team of autonomous underwater vehicles in the presence of loss of effectiveness (LOE) actuator faults is addressed. Towards this end, two different fault recovery control strategies based on the model predictive control technique as well as the dynamic game theory are proposed and developed. Given the allowable information that can be exchanged among the agents, both centralised and semi-decentralised recovery control schemes are considered and their associated corresponding fault recovery strategies are developed. The proposed active fault recovery control strategies incorporate both the online inaccurate as well as delayed actuator fault estimates to reconfigure the nominal (healthy state) controllers. The effectiveness of the proposed semi-decentralised fault recovery control schemes is quantitatively investigated through extensive simulation case studies considering various LOE actuator fault severities in one or more unmanned vehicles as well as fault detection and isolation module imperfections such as fault estimation error and time delays in detecting the faults. The simulation results demonstrate and illustrate that our proposed semi-decentralised recovery control scheme can maintain acceptable degraded tracking and formation keeping performance of both the faulty and healthy agents in the team with lower computational and communication bandwidth requirements as well as lower or fairly close control effort cost as compared to the centralised control recovery scheme.     

Adaptive fault diagnosis and fault-tolerant control of MIMO nonlinear uncertain systems

This article presents an integrated fault diagnosis and fault-tolerant control (FTC) methodology for a class of nonlinear multi-input–multi-output systems. Based on the fault information obtained during the diagnostic procedure, an FTC component is designed to compensate for the effect of faults. In the presence of a fault, a baseline controller guarantees the boundedness of all the system signals until the fault is detected. After fault detection and then again after isolation, the controller is reconfigured to improve the tracking performance using online fault diagnostic information. Under certain assumptions, the stability and tracking performances of the closed-loop system are rigorously investigated. It is shown that the system signals always remain bounded and the output tracking error converges to a neighbourhood of the origin of the state space.     

Using parallel program specifications for reactive control of underwater vehicles

This paper describes a situated reasoning architecture and a programming implementation for controlling robots in naturally changing environments. The reactive portion of the architecture produces reaction plans that exploit low-level competences as operators. The low-level competences include both obstacle avoidance heuristics and control-theoretic algorithms for generating and following a velocity/acceleration trajectory. Implemented in the GAPPS/REX situated automata programming language, robot goals can be specified logically and can be compiled into runtime virtual circuits that map sensor information into actuator commands in a fashion that allows for parallel execution. Detailed programs are described for controlling underwater vehicles being developed at the Woods Hole Oceanographic Institution, specifically the Remotely Piloted Vehicle (RPV), its successor, the Hylas, and eventually the Autonomous Benthic Explorer (ABE). Experiments with the RPV in a test tank are described in detail and will be duplicated with the Hylas. The experiments show that the robot performed both pilotaided and autonomous exploration tasks while accommodating normal changes in the task environment. ABE programs are described to illustrate how the reaction plans can be used in tasks more complex than those in the RPV experiments. The ABE is required to gather scientific data from deep ocean phenomena (e.g., thermal vents) which occur sporadically over long periods of time. A test tank simulation is described wherein the architecture is shown to easily generate robust vehicle control schemes which gather the required thermal vent data for a variety of vents of varying positions, velocities and extents.     

Kalman filter based fault diagnosis of networked control system with white noise

The networked control system NCS is regarded as a sampled control system with output time-variant delay. White noise is considered in the model construction of NCS. By using the Kalman filter theory to compute the filter parameters, a Kalman filter is constructed for this NCS.By comparing the output of the filter and the practical system,a residual is generated to diagnose the sensor faults and the actuator faults. Finally, an example is given to show the feasibility of the approach.     

Fault-tolerant traction control of electric vehicles

This paper investigates a new traction control approach that requires neither chassis velocity nor information about tire-road conditions. Plant fault subject to the uncertainties of the mathematical model and slightly sensor fault are concerned. For general traction control of vehicles, the variation of model behavior may break down the steering stability if the chassis velocity is not monitored. This paper presents a fault-tolerant approach based on the maximum transmissible torque estimation (MTTE) scheme which has the ability to prevent electric vehicles from skidding. A PI-type disturbance observer is employed to enhance the steering stability of the MTTE approach. This proposed approach does not require both the differentiator and the inversion of the controlled plant. Finally, illustrated examples are given for evaluating the fault-tolerant performance and feasibility of the presented anti-slip strategy.