双连杆柔性机械手负载自适应模糊滑模控制

讨论了柔性机械手末端负载变化时的控制问题.应用奇异摄动将双连杆柔性机械手系统分解为慢变、快变两个子系统.提出一种慢变子系统采用自适应模糊滑模控制、快变子系统采用最优控制的混合控制方法.仿真结果表明,该方法不仅能实现柔性机械手轨迹的快速、准确跟踪,有效的抑制弹性振动,并且对负载的变化具有强的鲁棒性.     

双连杆柔性机械手负载自适应模糊滑模控制

讨论了柔性机械手末端负载变化时的控制问题。应用奇异摄动将双连杆柔性机械手系统分解为慢变、快变两个子系统。提出一种慢变子系统采用自适应模糊滑模控制、快变子系统采用最优控制的混合控制方法。仿真结果表明,该方法不仅能实现柔性机械手轨迹的快速、准确跟踪,有效的抑制弹性振动,并且对负载的变化具有强的鲁棒性。     

基于神经网络与粒子滤波的柔性臂控制方法研究

基于奇异摄动法将单连杆柔性臂系统分解为慢变、快变子系统,采用混合控制方法;设计了基于粒子滤波的神经网络控制器来线性化慢子系统,使其跟踪期望轨迹;采用粒子滤波训练神经网络克服了BP算法收敛速度慢、易陷入局部极小值的缺陷,及扩展卡尔曼滤波方法带来的模型线性化损失;对于快变系统采用最优控制方法;仿真结果表明:在神经网络训练误差收敛速度及精度方面,粒子滤波要比BP及卡尔曼滤波要好;组合控制方法能有效地抑制柔性臂弹性振动,轨迹跟踪迅速准确,精度方面也是前者最优。     

基于模糊神经的柔性臂变负载控制方法

基于奇异摄动将单连杆柔性机械臂动力学模型分解为慢、快变子系统,传统方法分别采用PD控制和最优控制能取得较好控制效果,但负载不确定时,控制效果并不理想.提出对于慢变子系统,采用模糊神经、PD控制相结合的控制方法,对于快变子系统,采用模糊神经、最优控制相结合的控制方法.当负载变化时,采用模糊神经控制器根据实际负载对PD参数及最优控制参数进行调整,达到更优的控制效果.分别采用传统方法及本文提出的改进方法在变负载条件下作了仿真实验,结果表明后者的控制效果明显优于前者.给出了慢、快变子系统模糊神经控制器在变负载条件下训练参数的获取方法.     

参数不确定柔性机械手的快速终端滑模控制

针对具有参数不确定性的柔性机械手,采用重新定义系统输出的方法,将系统分解为输入输出子系统和零动态子系统.对于输入输出子系统提出了一种递阶快速终端滑模控制策略,使得输入输出子系统在有限时间内收敛.将零动态子系统在平衡点近似线性化以选择控制器的设计参数,使零动态子系统在平衡点附近渐近稳定,从而保证了整个柔性机械手系统的渐近稳定,对系统中的不确定性具有较强的鲁棒性.仿真结果验证了所提方法的正确性.     

基于混沌遗传算法的柔性机械手滑模控制器优化设计

针对柔性机械手动力学方程的非最小相位特点,本文提出一种柔性机械手的终端滑模控制方法,将关节电机转角和柔性模态变量的线性组合定义为柔性机械手系统的输出.通过输入输出线性化,将系统分解为输入输出子系统和零动态子系统.设计终端滑模控制策略,使输入输出子系统在有限时间收敛到零;利用混沌遗传算法优化控制器的设计参数,使零动态了系统在甲衡点附近渐近稳定,从而保证整个系统的渐近稳定.本文提出的方法设计过程简单,易于实现.仿真结果证明了设计的有效性.     

单连杆柔性臂负载自适应模糊滑模控制

针对单连杆柔性臂，提出了负载自适应模糊滑模控制与最优控制相结合的混合控制方法。首先，采用奇异摄动将系统分为慢变和快变两个子系统。然后，对慢变子系统采用负载自适应模糊滑模控制，快变子系统采用最优控制。最后，仿真结果表明，该方法不仅能实现柔性臂轨迹的快速、准确跟踪，有效地抑制弹性振动，并且对负载的变化具有强的鲁棒性。     

参数不确定柔性机械手的终端滑模控制

针对参数不确定双臂柔性机械手系统, 提出一种基于遗传算法的终端滑模控制方法, 以实现其末端控制.基于输出重定义方法, 通过输入输出线性化, 将系统分解为输入输出子系统和内部子系统. 设计终端滑模控制策略,使输入输出子系统有限时间内收敛到零, 内部子系统变为零动态子系统; 采用遗传算法优化零动态子系统参数, 使其在平衡点附近渐近稳定. 根据Lyapunov稳定性理论算出末端输出位移的误差范围. 仿真结果证明该方法有效性.     

基于鲁棒滑模观测器的两关节柔性机械手控制

柔性机械手系统为非最小相位系统, 当控制有界时, 该特性阻碍其端点位移渐近跟踪期望轨迹. 本文首先重新定义柔性机械手系统的输出, 通过输入输出线性化, 将系统分解为输入输出子系统和零动态子系统; 然后提出一种用于观测柔性模态导数的鲁棒滑模观测器, 使状态估计达到预期的指标, 解决了柔性模态导数难以获得的问题; 设计积分滑模控制策略, 使输入输出子系统在有限时间收敛到零; 选择适当的控制器参数, 使零动态子系统在 平衡点附近渐近稳定, 从而保证整个系统的渐近稳定. 本文提出的方法设计过程简单, 易于实现. 仿真结果证明了设计的有效性.     

基于分布参数机械臂协调操作柔性负载双时标控制

基于分布参数系统理论,建立机械臂协调操作柔性负载系统的动力学模型.利用奇异摄动方法,对动力学模型进行双时标分解,得到一个表征系统大范围刚性运动的集中参数慢变子系统和表征系统弹性振动的分布参数快变子系统.分别设计了自适应模糊滑模慢变控制器和振动反馈快变控制器,并通过分析快变子系统主算子及其生成C_O半群的特性,证明了分布参数闭环子系统的渐近稳定性.最后,通过仿真实验验证了所提出方法的有效性.     

Boundary Control for A Flexible Inverted Pendulum System Based on A Pde Model

A partial differential equation (PDE) model for a flexible inverted pendulum system (FIPS) is derived by the use of the Hamilton principle. To solve the coupling system model, a singular perturbation method was adopted. The PDE model was divided into a fast subsystem and a slow subsystem using the singular perturbation method. To stabilize the fast subsystem, a boundary control force was applied at the free end of the beam. It then was proven that the closed‐loop subsystem is appropriate and exponentially stable. For the slow subsystem, a sliding mode control method was employed to design a controller and the Linear Matrix Inequality (LMI) method was used to design the sliding surface. It then was shown that the slow subsystem is exponentially stable.     

Boundary Control for a Flexible Inverted Pendulum System Based on a PDE Model with Input Saturation

This research considers the control problem of a flexible inverted pendulum system (FIPS) in the presence of input saturation. The model for a flexible inverted pendulum system (FIPS) is derived via the Hamilton principle. The FIPS model is divided into a fast subsystem and a slow subsystem via the singular perturbation method. We introduce an auxiliary system to deal with the input saturation of a fast subsystem. To stabilize the fast subsystem, a boundary anti‐windup control force is applied at the free end of the beam. It is proven that the closed‐loop subsystem is stable. For the slow subsystem, a sliding mode control method is employed to design a controller and a new decoupling method to design the sliding surface. Then it is shown that the slow subsystem is stable. Finally, simulation results are provided to confirm the efficacy of the proposed controller.     

Dynamic modelling and adaptive robust tracking control of a space robot with two-link flexible manipulators under unknown disturbances

In this paper, both the closed-form dynamics and adaptive robust tracking control of a space robot with two-link flexible manipulators under unknown disturbances are developed. The dynamic model of the system is described with assumed modes approach and Lagrangian method. The flexible manipulators are represented as Euler–Bernoulli beams. Based on singular perturbation technique, the displacements/joint angles and flexible modes are modelled as slow and fast variables, respectively. A sliding mode control is designed for trajectories tracking of the slow subsystem under unknown but bounded disturbances, and an adaptive sliding mode control is derived for slow subsystem under unknown slowly time-varying disturbances. An optimal linear quadratic regulator method is proposed for the fast subsystem to damp out the vibrations of the flexible manipulators. Theoretical analysis validates the stability of the proposed composite controller. Numerical simulation results demonstrate the performance of the closed-loop flexible space robot system.     

Experimental study for trajectory tracking of a two-link flexible manipulator

In this paper, the dynamical equations of a two-link flexible manipulator moving in the vertical plane are derived. The system is divided into a fast subsystem and a slow subsystem via the singular perturbation method. Considering the characteristics of a flexible manipulator, a compensated controller is designed for each joint angle. A combined robust control algorithm is proposed, which includes a sliding mode variable structure for the slow subsystem and H infinity control strategy for the fast subsystem. Experimental results of this combined robust controller are compared with those of the standard PID controller and a significant performance is well demonstrated.     

Adaptive sliding mode trajectory tracking control for wheeled mobile robots

This paper discusses the problem of adaptive sliding mode trajectory tracking control for wheeled mobile robots in the presence of external disturbances and inertia uncertainties. A new fast nonsingular terminal sliding mode surface without any constraint is proposed, which not only avoids singularity, but also retains the advantages of sliding mode control. In order to implement the trajectory tracking mission, the error dynamic system is divided into a second-order subsystem and a third-order one. First, an adaptive fast nonsingular terminal sliding mode control law of the angular velocity is constructed for stabilising the second-order subsystem in finite time. Then, another adaptive fast nonsingular terminal sliding mode control law of the linear velocity is designed to guarantee the stability of the third-order subsystem. Finally, a simulation example is provided to demonstrate the validity of the proposed control scheme.     

Second-order terminal sliding mode control of uncertain multivariable systems

A second-order terminal sliding mode controller for uncertain multivariable systems is proposed in this paper. The controller adopts the hierarchical control structure. The paper derives the state transform matrices which are used to transform a multivariable linear system to the block controllable form consisting of two subsystems, an input–output subsystem and a stable internal dynamic subsystem. The proposed controller utilizes a non-singular terminal sliding mode manifold for the input–output subsystem to realize fast convergence and better tracking precision. Meanwhile, a chattering-free second-order terminal sliding mode control law is presented. The stability of uncertain multivariable systems can be realized using the proposed controller. A derivative estimator is utilized in the paper to estimate the derivatives of the sliding mode functions for the controller. The simulation results are presented to validate the design method.     

Composite Hierarchical Anti-Disturbance Control of a Quadrotor UAV in the Presence of Matched and Mismatched Disturbances

Quadrotor helicopter is an unstable system subject to matched and mismatched disturbances. To stabilize the quadrotor dynamics in the presence of these disturbances, the application of a composite hierarchical anti-disturbance controller, combining a sliding mode controller and a disturbance observer, is presented in this paper. The disturbance observer is used to attenuate the effect of constant and slow time-varying disturbances. Whereas, the sliding mode controller is used to attenuate the effect of fast time-varying disturbances. In addition, sliding mode control attenuates the effect of the disturbance observer estimation errors of the constant and slow time-varying disturbances. In this approach, the upper bounds of the disturbance observer estimation errors are required instead of the disturbances’ upper bounds. The disturbance observer estimation errors are found to be bounded when the disturbance observer dynamics are asymptotically stable and the disturbance derivatives and initial disturbances are bounded. Moreover, due to the highly nonlinear nature of the quadrotor dynamics, the upper bounds of a part of the quadrotor states and disturbance estimates are required. The nonlinear terms in the rotational dynamics are considered as disturbances, part of which is mismatched. This assumption simplifies the control system design by dividing the quadrotor’s model into a position subsystem and a heading subsystem, and designing a controller for each separately. The stability analysis of the closed loop system is carried out using Lyapunov stability arguments. The effectiveness of the developed control scheme is demonstrated in simulations by applying different sources of disturbances such as wind gusts and partial actuator failure.     

基于干扰观测器的解耦快速终端滑模控制

针对一类欠驱动系统跟踪控制问题,提出了一种基于非线性干扰观测器的全局解耦快速终端滑模控制(NDODGFTSMC)策略.将欠驱动系统分解成两个子系统分别设计全局快速终端滑模面,利用其中一个子系统滑模面的符号函数来构造中间变量,并将该变量引入到另一个子系统的滑模面中,构造出整个系统的滑模面,采用等效控制法和模糊双幂次趋近律...