Dynamic Modeling and Tracking Control of 2-Joint Manipulators in Ocean Current Environment北大核心CSCD

The hydrodynamic performance of the underwater manipulator is greatly influenced by the current load. The underwater environment is assumed to be a still water environment and the current load is only considered as a simple random disturbance in the current control research, and the traditional control precision is usually rather low. Based on the Lagrange method and the Newton-Euler method, a dynamic model for 2-joint manipulators in the uniform ocean current environment was derived. In view of the relative motion of the ocean current and the manipulator, the Morison formula was introduced to calculate the water resistance and the inertia force of the ocean current on the manipulator. Based on this dynamic model, the sliding mode control strategy was used to achieve accurate tracking of the ideal trajectory of the manipulator. The simulation results show that, compared with the PD (proportional derivative) control, the sliding mode control strategy has better control effects. © 2023 Editorial Office of Applied Mathematics and Mechanics. All rights reserved.     

基于终端滑模控制的扰动复杂网络的有限时间同步

本文研究了扰动的复杂网络的有限时间同步问题. 利用终端滑模控制的方法, 设计了能保证网络同步的滑模面和控制器, 得到了两个不同的复杂网络之间达到有限时间同步的充分条件. 这些理论结果推广了复杂网络同步的一些已有结论.     

Avoidance control

We consider dynamical systems subject to control by two agents, one of whom desires that no trajectory of the system, emanating from outside a given set, intersects the set, no matter what the admissible actions of the other agent. Conditions are given whose satisfaction assures that a given control results in avoidance. Furthermore, these conditions are constructive in that they yield an avoidance feedback control. Some examples are presented.     

永磁同步电机伺服系统的有限时间位置控制

研究了永磁同步电机伺服系统的位置跟踪问题.利用反馈线性化的思想,对永磁同步电机的数学模型进行分析,实现了电机模型的精确线性化和解耦.首先,将永磁同步电机位置跟踪系统采用反馈线性化技术变换为两个线性子系统,分别对其设计相应的基于连续状态反馈线性化的有限时间控制器,并设计了有限时间负载观测器来观测估计外部负载扰动.对永磁同步电机位置跟踪的闭环系统进行了稳定性的分析.与对应的渐近稳定控制的方案相比,基于有限时间的控制方案实现了永磁同步电机对期望信号的有限时间跟踪,获得了更好的动态响应和抗扰动性能.仿真结果表明了该控制方案的有效性.     

基于滑模方法的倒立摆台车系统的非线性控制

以倒立摆台车系统为研究对象,将系统状态分成两组,构造出一种双层滑动面,给出一种基于滑模控制的非线性控制律,并设计了控制器参数．然后采用Lyapunov方法,证明了各级滑动平面的稳定性,实现了台车在水平方向位置及摆角的渐近跟踪．     

混沌记忆系统的自适应反馈控制和轨迹跟踪控制

研究了混沌记忆系统的自适应反馈控制和基于反馈线性化的轨迹跟踪控制问题.首先,通过绘制系统的时域波形图和混沌吸引子图验证系统的复杂的动力学行为;然后,分别应用自适应反馈控制方法和基于反馈线性化的轨迹跟踪控制方法设计控制器,对系统施加控制;最后,通过数值仿真验证控制器的有效性.     

基于组合智能控制的柔性臂微机控制系统研究

针对难以控制的柔性机械臂,设计了强鲁棒性、强自适应能力的模糊滑模控制策略;并针对控制对象与控制算法的复杂性,设计了基于DSP＋FPGA的控制系统,保证了系统的实时性和精确度。     

具有时滞和参数不确定性的网络系统的滑模控制

研究了一类具有时滞的不确定网络控制系统(NCS)的滑模控制.首先,用一种特殊的变换将不确定时滞系统化为非延迟不确定系统形式.然后基于Lyapunov稳定性理论及线性矩阵不等式(LMI)技术,以线性矩阵不等式的形式给出了该系统的一些新的稳定性判据.所提出的控制器能够使具有不确定性的时滞系统渐近稳定性,而且控制器结构简单,计算方便.最后通过数值模拟,验证了所设计方法的有效性.     

Optimal Control of a Ship for Collision Avoidance Maneuvers

We consider a ship subject to kinematic, dynamic, and moment equations and steered via rudder under the assumptions that the rudder angle and rudder angle time rate are subject to upper and lower bounds. We formulate and solve four Chebyshev problems of optimal control, the optimization criterion being the maximization with respect to the state and control history of the minimum value with respect to time of the distance between two identical ships, one maneuvering and one moving in a predetermined way.Problems P1 and P2 deal with collision avoidance maneuvers without cooperation, while Problems P3 and P4 deal with collision avoidance maneuvers with cooperation. In Problems P1 and P3, the maneuvering ship must reach the final point with a given lateral distance, zero yaw angle, and zero yaw angle time rate. In Problems P2 and P4, the additional requirement of quasi-steady state is imposed at the final point.The above Chebyshev problems, transformed into Bolza problems via suitable transformations, are solved via the sequential gradient-restoration algorithm in conjunction with a new singularity avoiding transformation which accounts automatically for the bounds on rudder angle and rudder angle time rate.The optimal control histories involve multiple subarcs along which either the rudder angle is kept at one of the extreme positions or the rudder angle time rate is held at one of the extreme values. In problems where quasi-steady state is imposed at the final point, there is a higher number of subarcs than in problems where quasi-steady state is not imposed; the higher number of subarcs is due to the additional requirement that the lateral velocity and rudder angle vanish at the final point.     

分数阶时滞微分系统的滑模控制(英文)

The problem of sliding mode control for fractional differential systems with statedelay is considered.A novel sliding surface is proposed and a controller is designed correspondingly,such that the state starting from any initial value will move toward the switching surface and reach the sliding surface in finite time and the state variables on the sliding surface will converge to equilibrium point.And the stability of the proposed control design is discussed.     

Maximin Approach to the Ship Collision Avoidance Problem via Multiple-Subarc Sequential Gradient-Restoration Algorithm

The ideal strategy for ship collision avoidance under emergency conditions is to maximize wrt the controls the timewise minimum distance between a host ship and an intruder ship. This is a maximin problem or Chebyshev problem of optimal control in which the performance index being maximinimized is the distance between the two ships. Based on the multiple-subarc sequential gradient-restoration algorithm, a new method for solving the maximin problem is developed.Key to the new method is the observation that, at the maximin point, the time derivative of the performance index must vanish. With the zero derivative condition being treated as an inner boundary condition, the maximin problem can be converted into a Bolza problem in which the performance index, evaluated at the inner boundary, is being maximized wrt the controls. In turn, the Bolza problem with an added inner boundary condition can be solved via the multiple-subarc sequential gradient-restoration algorithm (SGRA).The new method is applied to two cases of the collision avoidance problem: collision avoidance between two ships moving along the same rectilinear course and collision avoidance between two ships moving along orthogonal courses. For both cases, we are basically in the presence of a two-subarc problem, the first subarc corresponding to the avoidance phase of the maneuver and the second subarc corresponding to the recovery phase. For stiff systems, the robustness of the multiple-subarc SGRA can be enhanced via increase in the number of subarcs. For the ship collision avoidance problem, a modest increase in the number of subarcs from two to three (one subarc in the avoidance phase, two subarcs in the recovery phase) helps containing error propagation and achieving better convergence results.     

Maximal distance for robotic simulation: The convex case

Given two hyper-rectangles inE ⁿ with sides having surface normals in the directions of the axes, each containing a set that touches all 2n sides of its containing hyper-rectangle, it is important to have an easily calculated upper bound on the distance between the sets, for use in a branch and bound algorithm applicable in collision avoidance in robotic simulation. In a previous paper, such a bound was given under the hypothesis that the sets are connected. Here, we consider the case where the sets are convex.The work of the second author was supported in part by the Natural Sciences and Engineering Research Council of Canada. The drawings were prepared by K. Stewart.     

Leader-follower strategy via a sliding mode approach

In this paper, the decision making problem in continuoustime dynamic systems is considered for the situation with two decision makers and a hierarchical decision structure. The leader-follower strategy is studied. To implement the leader's strategy, we propose to use a sliding mode approach, which allows the leader to constrain the state of the system within some manifold of the state space and forces the follower to choose the strategy preferable for the leader. The corresponding sliding manifolds are derived from the classical variational problem formulation for a class of systems whose right-hand side is affine with respect to the two control inputs. Numerical examples are considered with simulations to illustrate the technique.The authors wish to express their thanks to Dr. Vadim Utkin for his helpful discussions.     

具外部扰动的变时滞不确定奇异系统的滑动模态控制

研究了含有多个变时滞的不确定奇异系统的滑动模态问题.该系统相比文献中已研究的系统更为复杂,具有多个变时滞,且分别含有匹配和不匹配的外部扰动项.通过对系统进行等价分解化为两个子系统,对分解后的系统进行切换函数的设计,再通过定义Lyapunov函数得到使得系统的滑模运动渐近稳定的充分条件.由此证明了所设计的滑模控制率能够保证状态轨迹在优先时间内被驱动到指定的切换面上且保持运动.设计过程简单,且结果以线性矩阵不等式呈现,相比文献中已有的结论更易于实现.最后通过例子验证结论的正确性.