Adaptive tracking control of an autonomous underwater vehicle

This paper presents the trajectory tracking control of an autonomous underwater vehicle(AUV). To cope with parametric uncertainties owing to the hydrodynamic effect, an adaptive control law is developed for the AUV to track the desired trajectory. This desired state-dependent regressor matrix-based controller provides consistent results under hydrodynamic parametric uncertainties.Stability of the developed controller is verified using the Lyapunov s direct method. Numerical simulations are carried out to study the efficacy of the proposed adaptive controller.     

LDPC码在基于FH-FSK的AUV水声通信系统中的应用

水声信道严重的多途干扰和频率选择性衰落,将增加水声FH-FSK系统的平均误码率.此外,由于自主式水下交通工具(AUV)平台的运动特性,接收信号易产生时间选择性衰落,在接收端产生成串的突发错误甚至导致通信的中断.以上两方面因素将降低移动FH-FSK系统的可靠性,针对此问题,将多元低密度奇偶校验(LDPC)码与FH-FSK系统相结合,提出了一种基于多元LDPC码的水声FH-FSK系统.对比了基于二元LDPC码的FH-FSK系统与基于卷积码的FH-FSK系统的抗干扰性能,实验结果表明:前者具有更强的抗干扰能力.对比了基于多元LDPC码的FH-FSK系统与基于二元LDPC码的FH-FSK系统,仿真与实验结果表明:基于多元LDPC码的FH-FSK系统具有更强的抗干扰能力,可以进一步提高FH-FSK系统的可靠性.     

基于贝叶斯估计的水下机器人罗盘故障检测

以电子磁通门罗盘为例对自主水下机器人(Autonomous Underwater Vehicles,AUVs)传感器故障检测方法展开研究.针对电子罗盘极易受到周围磁场的影响而产生时对时错的数据这一问题,首先联立AUV的运动学和动力学方程得到AUV的全状态非线性模型;然后分析了电子罗盘的误差来源,建立了误差的模型;在此基础上,提出了基于贝叶斯估计的故障检测方法并给出了该方法离散形式的递推迭代公式;最后参照实际使用的电子罗盘的参数和AUV的机动能力,设计了仿真实验和外场试验,通过实验验证了该方法的正确性和有效性.     

基于改进双种群遗传算法的AUV路径规划方法研究

研究了在静态环境条件下AUV全局无碰撞的路径规划方法,提出了一种将顶点图像法与双种群遗传算法相结合的路径规划方法。利用顶点图像法建立环境模型,对候选路径进行二进制编码,然后利用改进的双种群遗传算法进行路径寻优。仿真实验表明,本文采用的改进双种群遗传算法是正确和有效的,具有运算速度快、全局优化能力强等优点。     

自主水下航行器的变质心跟踪控制

The trajectory-tracking control problem is investigated for an autonomous underwater vehicle (AUV) moving in the vertical plane using an internal point mass and a rear thruster as actuators. Combined with the dynamics of the point mass, the AUV is modeled as an underactuated system. A Lyapunov-based tracking controller is proposed by using backstepping approach to stabilize the error dynamics and force the position errors to a small neighborhood of the origin. Simulation results validate the proposed tracking approach.     

State feedback sliding mode control without chattering by constructing Hurwitz matrix for AUV movement

This paper presents a new method to eliminate the chattering of state feedback sliding mode control (SMC) law for the mobile control of an autonomous underwater vehicle (AUV) which is nonlinear and suffers from unknown disturbances system. SMC is a well-known nonlinear system control algorithm for its anti-disturbances capability, while the chattering on switch surface is one stiff question. To dissipate the well-known chattering of SMC, the switching manifold is proposed by presetting a Hurwitz matrix which is deducted from the state feedback matrix. Meanwhile, the best switching surface is achieved by use of eigenvalues of the Hurwitz matrix. The state feedback control parameters are not only applied to control the states of AUV but also connected with coefficients of switching surface. The convergence of the proposed control law is verified by Lyapunov function and the robust character is validated by the Matlab platform of one AUV model.     

Black‐box position and attitude tracking for underwater vehicles by second‐order sliding‐mode technique

In this work we address the tracking control problems for autonomous underwater vehicles (AUVs). The proposed solution is based on the variable structure systems (VSS) theory and, in particular, on the second‐order sliding‐mode (2‐SM) methodology. The tuning of the controller is carried out via black‐box approach, dispensing with the knowledge of the actual AUV parameters, by simply progressively increasing a single gain parameter. The presented stability analysis includes explicitly the unmodelled actuator dynamics and the presence of external uncertain disturbances. The good performance of the proposed scheme is verified by means of simulations on a 6‐DOF AUV. Copyright © 2009 John Wiley & Sons, Ltd.     

基于扩展卡尔曼滤波器的AUV导航定位数据融合

导航定位是AUV(自主式水下潜器)自动化受限的关键技术.GPS等单独的定位方式又存在缺陷.故采用低成本罗经-DVL-GPS组合导航定位.因为导航定位观测的非线性关系,设计了基于扩展卡尔曼滤波器的导航定位数据融合算法.针对扩展卡尔曼滤波器存在的滤波发散现象,引入机动目标模型抑制滤波发散,研究并仿真了AUV的两种运动方式,实现了覆盖四个象限运动的导航定位仿真,结果表明算法能有效进行数据融合,提高状态估计精确度.     

具有PID反馈增益的自主水下航行器反步法变深控制

本文针对海底地形测绘时自主水下航行器(autonomous underwater vehicle,AUV)的变深控制问题,提出具有PID增益调节的AUV深度控制方法,基于反馈增益的反步法设计控制器,避免了采用传统反步法导致控制器中存在虚拟控制量的高阶导数问题;基于李雅普诺夫稳定性理论设计控制器参数消除了部分非线性项,得到的控制器的线性部分为状态变量的线性组合,具有PID控制器参数调节的形式;针对存在建模不精确、外界干扰和测量噪声时的闭环系统鲁棒性进行分析,保证了误差系统在扰动作用时的一致最终有界性.最后通过仿真实验验证了本文设计的控制器的有效性.