为了解决单一预报模型对复杂的船舶横摇运动姿态时间序列建模预报困难以及支持向量机预报方法离线训练导致实时性差的问题,文中提出一种分解域船舶运动姿态在线预报方法.采用经验模式分解法对时序的不同特征信息进行分解;应用游程法将分量重构为高、中、低频三个分量;针对每个分量建立在线最小二乘支持向量机预报模型,对各分量的预报结果累加得出最终预报值.对某船横摇角时序进行了预报,结果表明,所提方法预报10s的相对均方误差在13％以内,相比于支持向量机预报模型,该模型能够有效提高预报精度和效率.

For attitude tracking control of the spacecraft rendezvous and docking simulator, this paper designs two finite-time active disturbance rejection controllers by using an improved fast nonsingular terminal sliding mode surface and an improved adaptive law under the condition of external disturbances and inertia uncertainties existing. The proposed controllers of the improved adaptive control architecture are continuous, which can inhibit the disturbance effectively, meanwhile, the second controller can resolve the problem of the boundary layer theory that finite-time stability is lost within the boundary layer. The Lyapunov theory and simulation results show that the two proposed controllers can guarantee the finite-time stability of the system, and the system can converge to the equilibrium point quickly.

In order to realize path following control for underactuated surface vessels under parameter perturbation and external disturbances, a neural sliding mode controller is presented based on visible distance. The desired position and the current position are used to determine the reference surge velocity and yawing angle by using visible distance, which are employed as the virtual control laws in stabilizing the position errors. Then, a new nonlinear feedback robust controller is designed based on neural network and sliding modes to realize the tracking control of the virtual control laws without determining upper bound of parameter perturbation and external disturbances. The problem of saturation and chattering of the controller are circumvented. The results of simulation experiments indicate that the controller is robust against parameter perturbation and external disturbances. Moreover, the path following control with can be achieved by the proposed control method.

The paper studies the formation control problem for multiple underactuated surface vessels by utilizing leader-follower approach with parameter uncertainties and external disturbances, and the proposed formation control method that the follower tracks a reference trajectory based on the leader's position and the predetermined formation without the need for leader's velocity and dynamics. A virtual ship is constructed such that its trajectory converges to the reference trajectory of the follower in limited time. The Ships formation control model is established on the virtual ship under leader-follower mode. The robust controller can effectively deal with parameter uncertainties and external disturbances by combining backstepping with sliding-mode control method, which can make the follower move along the trajectory of the virtual ship, maintain the desired formation with leader and achieve the purpose of formation control. A Simulation of the formation control for the multiple underactuated surface vessels is performed by using three real Northern Clippers. Results validate the effectiveness of the proposed method.

现有的基于理论模型、半经验模型及经验模型的船间水动力干扰力和干扰力矩计算公式比较复杂,不适于驾引人员实际操船的应用.为快速、准确计算船间水动力干扰力和干扰力矩,帮助驾引人员迅速分析对遇条件下两船间的水动力影响情况,对Vantorre等人的船间水动力干扰缩尺船模试验中的一组船舶对遇试验数据运用不同的回归方法进行拟合,以优化得到一个相对精确、计算简单的船间水动力干扰计算模型.此模型可供船舶驾引人员迅速估计对遇条件下的船间水动力影响,在一定程度上可为驾引人员的操纵提供判断依据.

In order to realize tracking control for underactuated surface vessels with parameter uncertainties and external disturbances, a nonsingular terminal sliding mode method was proposed. The controller was divided by backstepping method into the kinetic part and the dynamic part. In the kinetic process, the reference surge and sway velocities are employed as the virtual control law in stabilizing the position errors. In the dynamic process, the virtual control law was considered the new tracking target, and the real control law was designed by the nonsingular terminal sliding-mode method to realize the tracking control of the reference velocities. This method can not only guarantee the position tracking error converge finite time, but also ensure yawing motion is BIBO stable. Eventually, simulation experiment of real ship is performed. Results validate the proposed controller can achieve fast tracking control of USV in finite time under parameter uncertainties and external disturbances.

In order to realize tracking control for underactuated surface vessels with parameter uncertainties and external disturbances, a command filter feedback combined with sliding mode method is proposed. The tracking error equations are established based on CFB, which puts tracking control into stabilize surge speed and course angle error using transformation equation. Then, a nonlinear sliding mode controller is designed based on integration ideas. The problem of analytical and numerical differentiation of the virtual control laws is overcome, chattering of control input is circumvented, and the static error and overshoot are decreased. The results of simulation experiments indicate that the controller is robust against the systemic variations and time-varying external disturbances. Moreover, the tracking control with high tracking precision can be achieved by the proposed control method.

This paper addresses the exponential stabilization problem of underactuated surface vessels. The ships under consideration are not actuated in the sway direction, and the mass and damping matrices are not assumed to be diagonal. By using the cascaded system theory and backstepping approach, a discontinuous control law is proposed to make the origin of an under actuated ship k-exponentially stable. The effectiveness of the proposed control law is verified by simulation. © 2013 Springer Science+Business Media.

An improved simultaneous localization and mapping(SLAM) method based on extended Kalman filter(EKF) is presented to solve the SLAM problem of mobile robot with omnidirectional vision. The environment feature is extracted from the environment information around the mobile robot got by onmidirectional vision, then the landmark is located, finally, the position and attitude of the mobile robot and the map library are updated synchronously by using the EKF algorithm. Simulation results and real robot experiment results indicate the effectiveness and accuracy of the proposed approach.

A robust adaptive controller with guaranteed transient performance under a desired compensation adaptation law is developed for trajectory tracking control of robot manipulator in the presence of parametric uncertainties and external disturbances.With some modifications to the conventional adaptation law,a new control law is redesigned by combining the design methodologies of adaptive control and sliding mode control.The adaptive scheme has best computationally efficient for real-time calculating of the regressor,and compensate nonlinear friction and external disturbances via thought of variable structure.The global asymptotic stability is validated by Lyapunov direct method.Because the adaptation law is robust to uncertainty,the parameter is not contaminated with noise,simulation results show the estimated parameters are converged and the good robust and accuracy are obtained.