Using Common LISP in the EAVE autonomous underwater vehicle

The Marine Systems Engineering Laboratory of the University of New Hampshire has ported the University of Utah's Portable Common LISP Subset (PLCS) to the experimental autonomous vehicle (EAVE) underwater autonomous vehicle. Using Common LISP in the EAVE autonomous vehicle is expected to improve programmer productivity and software portability. Using the LISP interpreter allows for software changes to be made while in the field, thus saving time during vehicle operations. Issues concerning the operation of LISP in a real-time environment, such as the impact of garbage collection (GC), have been resolved by using an efficient version of Common LISP and by using LISP) at the high-end of a time-based software hierarchy     

A hierarchical real-time control architecture for a semi-autonomous underwater vehicle

This paper describes a real-time control architecture for Dual Use Semi-Autonomous Underwater Vehicle (DUSAUV), which has been developed at Korea Research Institute of Ships and Ocean Engineering (KRISO) for being a test-bed of development of underwater navigation and manipulator technologies. DUSAUV has three built-in computers, seven thrusters for six DOF motion control, one 4-function electric manipulator, one ballasting motor, built-in power source, and various sensors. A supervisor control system with GUI and a multi-purpose joystick is mounted on the surface vessel and communicates with vehicle through a fiber optic link. Furthermore, QNX, one of real-time operating system, is ported on the built-in control and navigation computers for real-time control purpose, while Microsoft OS product is ported in the supervisor computer for GUI programming convenience. A hierarchical control architecture, which consists of application layer, real-time layer and physical layer, has been developed for efficient control system of above complex underwater robotic system. The experimental results with implementation of the layered control architecture for various motion control of DUSAUV in an ocean engineering basin of KRISO is also presented.     

Robust control for underwater vehicle systems with time delays

A robust control scheme is presented for controlling systems with time delays. The scheme is based on the Smith controller and the LQG/LTR (linear quadratic Gaussian/loop transfer recovery) methodology. The methodology is applicable to underwater vehicle systems that exhibit time delays, including tethered vehicles that are positioned through the movements of a surface ship and autonomous vehicles that are controlled through an acoustic link. An example, using full-scale data from the tethered vehicle ARGO, demonstrates the developments     

Model-free adaptive control method with variable forgetting factor for unmanned surface vehicle control

We present a new type of model-free adaptive control (MFAC) method based on an adaptive forgetting factor for unmanned surface vehicle (USV) heading control under uncertain influence. Firstly, we analyze the compact form dynamic linearization based MFAC (CFDL-MFAC) method and its main problems with regard to USV heading control. Secondly, in order to address the problems of overshoot, oscillation, and slow convergence of the heading control with the MFAC method and considering the dynamics of the USV heading control subsystem, we introduce an adaptive forgetting factor into the CFDL-MFAC to arrive at the CFDL-MFAC with variable forgetting factor (CFDL-MFAC-VFF) method. Our simulation studies show that the CFDL-MFAC-VFF method yields low overshoot and low oscillations and is insensitive to changes in the system parameters and output error. Finally, our field experiments with the small USV “Dolphin-I” demonstrate the effectiveness and engineering practicability of our proposed method.     

浅海管线检测维修潜水器控制系统自航模试验

浅海海底管线检测维修潜水器是具有复杂动力特性和作业方式的特种载人潜水器，其作业需配备姿态及航行自动控制系统。为了保证其自动控制系统研制成功，研制了1：8缩尺的自航模作为平台，将实际控制系统方案遵循相似性准则改造为自航模控制系统，包括校正与补偿回路、指令分配器、姿态控制回路、航行控制回路。在海洋工程水池模拟风浪流等海洋环境，进行各种情况下的控制试验，对实现的控制律加以验证和改进，这些改进又按照相似性准则反映到实际控制系统方案的修正中。控制系统的设计方案由此得到全面验证和改善。     

海底管线检修潜水器垂直面控制及自航模试验

论述了纵倾控制律设计及自航模试验。首先选择一系列深度,对同一深度采用频域校正法单独设计控制律,使之对不同的速度和漂角具有足够的稳态精度和抗干扰性,这些控制律被集成统一为纵倾控制器,并根据潜深变化进行切换,对于其它深度采用同样的方法设计。控制器首先通过计算机仿真,然后进行自航模试验验证。设计的纵倾控制系统同时在其他试验项目中(水下管线跟踪和动力定位)发挥了重要的作用。     

Information fusion model-free adaptive control algorithm and unmanned surface vehicle heading control

Based on the model-free adaptive control (MFAC) theory, the heading control problem of unmanned surface vehicles (USVs) with uncertainties is explored. First, as a USV’s heading subsystem does not satisfy the quasilinear assumption of the MFAC theory, a new type of input and output information fusion MFAC, i.e., the IOIF–MFAC algorithm is proposed. The novel algorithm proposed herein renders the MFAC theory applicable to the heading control of USVs. Next, the input and output information of the heading subsystem, namely the rudder angle and heading angle, are combined, and the data model of the heading subsystem is subsequently deduced using a compact format dynamic linearization method. Based on which, the stability of the control system is proved. Finally, the effectiveness and practicability of the IOIF–MFAC algorithm are verified by simulation and field experiments through the “Dolphin IB” test platform developed by our group.     

Robust control for an autonomous underwater vehicle that suppresses pitch and yaw coupling

Attitude control systems for autonomous underwater vehicles are often implemented with separate controllers for pitch motion in the vertical plane and yaw motion in the horizontal plane. We propose a novel time-varying model for a streamlined autonomous underwater vehicle that explicitly displays the coupling between yaw and pitch motion due to nonzero roll angle and/or roll rate. The model facilitates the use of a multi-input multi-output H_∞ control design that is robust to yaw-pitch coupling. The efficacy of our approach is demonstrated with field trials.     

潜水器控制系统层次故障诊断模型设计

在潜水器控制系统的基础上,按照结构、功能和组件的关系,为潜水器控制系统进行故障诊断建模。依据基于模型的层次故障诊断技术,建立了适用于潜水器控制系统故障诊断的具体诊断和推理策略,开发了故障诊断软件系统,描述了故障诊断具体过程,并利用数字仿真验证系统设计的有效性。     

Design of a sliding mode fuzzy controller for the guidance and control of an autonomous underwater vehicle

This work demonstrates the feasibility of applying a sliding mode fuzzy controller to motion control and line of sight guidance of an autonomous underwater vehicle. The design method of the sliding mode fuzzy controller offers a systematical means of constructing a set of shrinking-span and dilating-span membership functions for the controller. Stability and robustness of the control system are guaranteed by properly selecting the shrinking and dilating factors of the fuzzy membership functions. Control parameters selected for a testbed vehicle, AUV-HM1, are evaluated through tank and field experiments. Experimental results indicate the effectiveness of the proposed controller in dealing with model uncertainties, non-linearities of the vehicle dynamics, and environmental disturbances caused by ocean currents and waves.     

无人船运动控制方法综述

为实现无人船海上自主作业,无人船运动控制的快速性、准确性以及鲁棒性亟待提高。首先从全驱动控制和欠驱动控制角度,分别概括了国内外无人船航向控制、航速控制、轨迹跟踪控制以及路径跟踪控制的主流控制方法。其次,归纳总结了处理海洋环境不确定扰动的研究进展,包括扰动的建模和消除、抑制扰动的主流方法。最后,总结了无人船运动控制现状与存在的问题,并从工程应用和理论研究两个角度对未来的研究方向进行了展望。     

Nonlinear adaptive control of an underwater towed vehicle

This paper addresses the problem of simultaneous depth tracking and attitude control of an underwater towed vehicle. The system proposed uses a two-stage towing arrangement that includes a long primary cable, a gravitic depressor, and a secondary cable. The towfish motion induced by wave driven disturbances in both the vertical and horizontal planes is described using an empirical model of the depressor motion and a spring-damper model of the secondary cable. A nonlinear, Lyapunov-based, adaptive output feedback control law is designed and shown to regulate pitch, yaw, and depth tracking errors to zero. The controller is designed to operate in the presence of plant parameter uncertainty. When subjected to bounded external disturbances, the tracking errors converge to a neighbourhood of the origin that can be made arbitrarily small. In the implementation proposed, a nonlinear observer is used to estimate the linear velocities used by the controller thus dispensing with the need for costly sensor suites. The results obtained with computer simulations show that the controlled system exhibits good performance about different operating conditions when subjected to sea-wave driven disturbances and in the presence of sensor noise. The system holds promise for application in oceanographic missions that require depth tracking or bottom-following combined with precise vehicle attitude control.     

Depth-trim mapping control of underwater vehicle with fins

Underwater vehicle plays an important role in ocean engineering.Depth control by fin is one of the difficulties for underwater vehicle in motion control.Depth control is indirect due to the freedom coupling between trim and axial motion.It includes the method of dynamic analysis and lift-resistance-coefficient experiment and theory algorithm.By considering the current speed and depth deviation,comprehensive interpretation is used in object-planning instruction.Expected depth is transformed into expected trim.Dynamic output fluctuation can be avoided,which is caused by linear mapping of deviation.It is steady and accurate for the motion of controlled underwater vehicles.The feasibility and efficiency of the control method are testified in the pool and natural area for experiments.     

Discrete-time quasi-sliding mode control of an autonomousunderwater vehicle

This paper presents a discrete-time quasi-sliding mode controller for an autonomous underwater vehicle (AUV) in the presence of parameter uncertainties and a long sampling interval. The AUV, named VORAM, is used as a model for the verification of the proposed control algorithm. Simulations of depth control and contouring control are performed for a numerical model of the AUV with full nonlinear equations of motion to verify the effectiveness of the proposed control schemes when the vehicle has a long sampling interval. By using the discrete-time quasi-sliding mode control law, experiments on depth control of the AUV are performed in a towing tank. The controller makes the system stable in the presence of system uncertainties and even external disturbances without any observer nor any predictor producing high rate estimates of vehicle states. As the sampling interval becomes large, the effectiveness of the proposed control law is more prominent when compared with the conventional sliding mode controller     

基于分布式控制力矩陀螺的水下航行器轨迹跟踪控制

基于控制力矩陀螺群(CMGs)的水下航行器具有低速或零速机动的能力。采用基于分布式CMGs的水下航行器方案,并研究其水平面的轨迹跟踪控制问题。通过全局微分同胚变换将非完全对称的动力学模型解耦成标准欠驱动控制模型,并根据简化的模型构建其轨迹跟踪的误差动力学模型,将轨迹跟踪控制问题转化为误差模型镇定问题。基于一种分流神经元模型和反步法设计了系统的轨迹跟踪控制律,该控制器不需要对任何虚拟控制输入进行求导计算,且能确保跟踪误差的最终一致有界性。仿真结果表明该控制器能够实现在不依赖动力学参数先验知识的情况下对光滑轨迹的有效跟踪。     

Design and reliability analysis of DP-3 dynamic positioning control architecture

As the exploration and exploitation of oil and gas proliferate throughout deepwater area,the requirements on the reliability of dynamic positioning system become increasingly stringent.The control objective ensuring safety operation at deep water will not be met by a single controller for dynamic positioning.In order to increase the availability and reliability of dynamic positioning control system,the triple redundancy hardware and software control architectures were designed and developed according to the safe specifications of DP-3 classification notation for dynamically positioned ships and rigs.The hardware redundant configuration takes the form of triple-redundant hot standby configuration including three identical operator stations and three real-time control computers which connect each other through dual networks.The function of motion control and redundancy management of control computers were implemented by software on the real-time operating system VxWorks.The software realization of task loose synchronization,majority voting and fault detection were presented in details.A hierarchical software architecture was planed during the development of software,consisting of application layer,real-time layer and physical layer.The behavior of the DP-3 dynamic positioning control system was modeled by a Markov model to analyze its reliability.The effects of variation in parameters on the reliability measures were investigated.The time domain dynamic simulation was carried out on a deepwater drilling rig to prove the feasibility of the proposed control architecture.     

开架式水下机器人运动的模糊非线性PD控制方法

由于水下机器人系统的非线性动力学特性和工作环境的复杂性和不确定性,如何更好地设计水下机器人作业时的运动控制器一直是其实用化过程中没能得到很好解决的问题。结合模糊逻辑和S面控制,利用T—S推理结构,设计了一种兼具局部和全局调整功能的模糊非线性PD(m)控制器,仿真结果表明,其控制效果要优于采用单一控制参数的S面控制器。     

Preliminary experiments in model-based thruster control forunderwater vehicle positioning

This paper reports comparative experiments with two novel and one conventional thrust control algorithms for the unsteady (transient) control of thrust generated by conventional bladed-propeller marine thrusters. First, comparative experiments with three different thrust control algorithms over a wide range of unsteady operating conditions suggest that model-based control algorithms offer transient thrust-control performance superior to that of their nonmodel-based counterpart. Second, hybrid simulations combining actual real-time experimental thruster responses with simulated one-dimensional real-time vehicle dynamics suggest that model-based thrust control algorithms offer vehicle position control superior to that of its nonmodel-based counterpart     

A task-based hierarchical control strategy for autonomous motion of an unmanned surface vehicle swarm

In this paper, a hierarchical control framework with relevant algorithms is proposed to achieve autonomous navigation for an underactuated unmanned surface vehicle (USV) swarm. In order to implement automatic target tracking, obstacle avoidance and avoid collisions between group members, the control framework is divided into three layers based on task assignments: flocking strategy design, motion planning and control input design. The flocking strategy design transmits some basic orders to swarm members. Motion planning applies the potential function method and then improves it; thus, the issue of autonomous control is transformed into one of designing the velocity vector. In the last layer, the control inputs (surge force and yaw moment) are designed using the sliding mode method, and the problem of underactuation is handled synchronously. The proposed closed-loop controller is shown to be semi-asymptotically stable by applying Lyapunov stability theory, and the effectiveness of the proposed methodology is demonstrated via numeric simulations of a homogeneous USV swarm.     

Three-dimensional visualization of mission planning and control forthe NPS autonomous underwater vehicle

The Naval Postgraduate School (NPS) is constructing a small autonomous underwater vehicle (AUV) with an onboard mission control computer. The mission controller software for this vehicle is a knowledge-based artificial intelligence (AI) system requiring thorough analysis and testing before the AUV is operational. The manner in which rapid prototyping of this software has been demonstrated by developing a controller code on a LISP machine and using an Ethernet link with a graphics workstation to simulate the controller's environment is discussed. The development of a testing simulator using a knowledge engineering environment (KEE) expert system shell that examines AUV controller subsystems and vehicle models before integrating them with the full AUV for its test environment missions is discussed. This AUV simulator utilizes an interactive mission planning control console and is fully autonomous once initial parameters are selected