Tracking control of second‐order chained form systems by cascaded backstepping

A design methodology is presented for tracking control of second‐order chained form systems. The methodology separates the tracking‐error dynamics, which are in cascade form, into two parts: a linear subsystem and a linear time‐varying subsystem. The linear time‐varying subsystem, after the first subsystem has converged, can be treated as a chain of integrators for the purposes of a backstepping controller. The two controllers are designed separately and the proof of stability is given by using a result for cascade systems. The method consists of three steps. In the first step we apply a stabilizing linear state feedback to the linear subsystem. In the second step the second subsystem is exponentially stabilized by applying a backstepping procedure. In the final step it is shown that the closed‐loop tracking dynamics of the second‐order chained form system are globally exponentially stable under a persistence of excitation condition on the reference trajectory. The control design methodology is illustrated by application to a second‐order non‐holonomic system. This planar manipulator with two translational and one rotational joint (PPR) is a special case of a second‐order non‐holonomic system. The simulation results show the effectiveness of our approach. Copyright © 2002 John Wiley & Sons, Ltd.     

A COMBINED SLIDING MODE‐GENERALIZED PI CONTROL SCHEME FOR SWINGING UP AND BALANCING THE INERTIA WHEEL PENDULUM

In this note we propose a control strategy which combines sliding modes and generalized PI (GPI) control for the swinging up, and stabilization around its unstable vertical position of the inertia wheel pendulum. Both tasks are achieved using a single controller. The pendulum angular position is assumed to be the only measured output variable. We show that this control scheme is robust with respect to constant torque disturbances. The proposed controller is used in an actual experimental setup.     

具有非驱动关节机器人的位置闭环控制

以具有非驱动关系的水平两自由度机械手为对象，建立了其动力学数学模型，对具有非完全约束机器人的特点进行了分析，利用解非线性方程的有效方法平均值法对模型进行了处理，得到平均值系统，使模型得到简化，在此基础上，针对平均系统，利用李亚普诺夫稳定性方法设计了非驱动关系的任意位置闭环控制，仿真结果表明平均系统与原真实系统具有相同的动力学特性，且设计的位置环控制方法是有效的。     

一类二阶非完整系统的镇定

研究一类二阶非完整系统的镇定问题. 通过状态和输入反馈变换将系统模型转换为二阶链式标准型, 并对标准型给出一种时变光滑指数镇定控制律. 所得结果应用于欠驱动平面刚体的镇定.     

自主式水下航行器控制技术新进展

自主式水下航行器是一个复杂的智能化机电系统，是能够在复杂的海洋环境中自主执行各种任务的无人平台。近年来，自主式水下航行器（AUV）控制技术取得了长足进展，本文较全面概括了近年来国内外在AUV控制技术领域的最新进展，主要包括基于控制器设计的建模、推进器建模与控制、动力定位控制、推力矢量控制、欠驱动控制等方面，然而目前AUV控制领域面临的难点主要在模型不确定和扰动不确定、传感器信息不足以及欠驱动系统的本质特性（例如可控性）及其控制方法等方面，还需要人们为之付出不懈的努力。     

一类非确定欠驱动系统的串级模糊滑模控制

本文针对一类含有非确定项的欠驱动系统提出了一种串级模糊滑模控制方法.该方法先选取状态变量中两个相关联的系统状态构造第一级滑动平面,然后将第一级滑模函数作为一个广义状态,与剩下系统状态中的一个状态构造第二级滑动平面,直到所有的系统状态都包含在内构造最后一级滑动平面.同时考虑到系统模型中存在的不确定项,利用模糊逻辑的逼近功能进行估计,文中采用Lyapunov方法求取了控制器的控制律以及模糊逼近的有关参数的自适应律.该串级模糊滑模控制器能够保证各级滑动平面的稳定性,并且在仿真实验中得到了验证.     

欠驱动水下机器人三维轨迹跟踪有限时间预设性能控制

本文研究了具有不确定动态和未知时变海洋环境扰动的欠驱动水下机器人(AUVs)三维轨迹跟踪有限时间预设性能控制问题,提出新型预设性能函数和误差映射函数,将受预设性能限制的轨迹跟踪误差转变为非受限的变换后误差;构造新的超螺旋(ST)扩张状态观测器,在有限时间内实时估计AUV不确定动态和未知时变海洋环境扰动引起的总扰动;基于...     

Adaptive output-feedback formation control for underactuated surface vessels

ABSTRACT

This paper investigates the leader–follower formation problem of underactuated surface vessels. Velocities of both leader and follower vessels are unavailable. Model uncertainties and ocean disturbances are also considered. By incorporating adaptive control, neural networks (NNs), the high-gain observer (HGO) and the minimal learning parameter (MLP) algorithm in the backstepping procedure, a novel adaptive output-feedback formation control scheme is developed. We show that formation errors can be guaranteed to be semiglobally uniformly ultimately bounded (SGUUB) with the proposed controller. Compared with existing methods, the formation can be achieved only with position and yaw angle of both leader and follower. Meanwhile, the developed scheme can enhance the robustness of the closed-loop system with less computational effort, where only two online parameters need to be tuned. Simulation and comparison results are provided to illustrate the effectiveness of theoretical results.     

仿猿双臂手机器人连续摆荡移动优化与实验

针对仿生悬摆机器人在连续移动过程中不能可靠抓握目标杆的问题,提出调整双手抓杆构形使势能最大、摆荡运动关节轨迹优化、大阻尼切换与大阻尼抓杆的分阶段控制策略.给出分阶段控制下各主动驱动关节PID控制器的期望目标关节轨迹计算公式和各阶段光滑运动的切换条件,利用ADAMS与MATLAB/Simulink软件进行仿猿双臂手机器人连续抓握不同间距目标杆的移动控制仿真.用自行研制的BARDAH-I型仿猿双臂手机器人分别进行了起始杆与中间杆间距1 m,中间杆与目标杆间距依次为0.5、0.6、0.7、0.8 m总计12次实验,实验成功率100%.实验结果证明所提出的控制方法能够有效提高仿猿双臂手机器人连续移动的成功率.     

Path tracking of underactuated ships with general form of dynamics

This article considers the path tracking problem for underactuated ships with general form of dynamics including uncertainties. By introducing certain two polar coordinate transformations, the ship's tracking kinematics and dynamics can be transformed into certain two-inputs–two-outputs nonlinear strict-feedback form. To avoid possible singularity problem in the backstepping control design, we introduce an asymptotic modification of orientation concept. Presented tracking scheme can guarantee the uniformly ultimately boundedness of closed-loop system in terms of polar coordinates. For the convenience of comparison with previous related works, where all tracking schemes were discussed in the Cartesian frame, we carry out some case studies to investigate the conditions under which the proposed tracking method can guarantee the same stability and convergence properties of tracking errors in the Cartesian frame. Numerical simulation studies are also carried out to demonstrate the effectiveness of presented tracking scheme.