机械臂的改进固定时间滑模控制方法设计

当机械臂末端对给定轨迹进行跟踪控制时,跟踪误差收敛速度容易受初始跟踪误差大小的影响,针对这一问题设计了一种适用于机械臂模型的改进固定时间滑模轨迹跟踪控制策略.在快速终端滑模面的基础上,设计了一种固定时间滑模面,从而使得控制器具有固定时间收敛特性并给与证明;针对滑模控制伴随抖震的特性,对滑模控制器的趋近律进行了抑制抖振的...     

非时间参考的移动机器人变滑模控制

提出一种基于非时间参考移动机器人的变滑模控制方法，设计以一定的速度跟踪路径的控制器，买现对一类轨迹的跟踪。由于采用变滑模控制，增强了机器人在不确定环境下的跟踪能力和系统鲁棒性，可以实现机器人在动态环境中的路径跟踪。买验验证了该方法的有效性。     

光电跟踪系统快速捕获时间最优滑模控制技术

针对光电跟踪系统目标的快速捕获过程,本文提出了时间最优滑模控制方法。该控制的滑模面函数为时间最优控制系统状态最优运动轨迹,保证系统状态变量沿着最优轨迹滑动;设计相应的指数趋紧率,使状态变量快速平稳趋近滑模面。以180°、90°、60°阶跃信号为捕获目标进行仿真与实验研究,实验结果为时间最优滑模控制调节时间比时间最优控制和滑模控制分别减小了约43.66%、59.67%,超调量为0,稳态波动量为0,稳态误差减小了约为44.94%和62.34%,与仿真结果相吻合。结果表明该方法调节时间短,超调小,稳态值平稳,稳态误差小,鲁棒性强等优点适合应用于光电跟踪系统目标快速捕获,具有重要的研究与应用价值。     

挖掘机基于干扰观测器的滑模控制

针对挖掘机工作装置的参数不确定和存在干扰的问题,将滑模控制用于挖掘机工作装置的轨迹跟踪控制中。为了削弱滑模控制中存在的抖振,设计了干扰观测器,对干扰项进行有效估计以降低滑模控制中的切换增益。利用Matlab／Simulink工具箱对所设计的控制器进行了仿真,给出了基于干扰观测器的滑模控制的跟踪性能及误差。     

阀控缸系统有限时间滑模控制

针对阀控缸系统稳态跟踪误差的收敛时间均为非有限时间内收敛到0的问题，提出了一种终端滑模控制方法。解决了液压系统非有限时间收敛问题，使得跟踪误差在有限时间内收敛到0。首先，运用终端滑模控制方法通过构造终端函数方式引入非线性项，设计终端滑模面来保证系统的全局鲁棒性和稳定性；其次，基于Lyapunov稳定性理论设计终端滑模控制器，保证位置跟踪误差在有限时间内收敛到0并验证其稳定性；最后，利用阀控缸系统模型以正弦信号及其衍生信号为参考信号对控制策略进行Simulink仿真，表明了终端滑模控制方法的可行性与有效性。     

机械臂固定时间观测器和自适应滑膜控制方法的设计

在机械臂轨迹跟踪控制过程中,当利用观测器对模型参数不确定性和外部未知动态扰动进行估计时,估计时间容易受扰动初值的影响,为此基于固定时间扰动观测器设计了一种自适应滑模轨迹跟踪控制方法。利用固定时间观测器的特性,在固定时间内获得机械臂内部模型误差和外部不确定扰动的估计,对扰动估计做出补偿,通过滑模控制策略实现机械臂的轨迹跟踪控制。针对滑模控制伴随抖震的特性,论文对滑模控制器的趋近律进行了抑制抖震的改进设计。通过仿真实验证明:基于固定时间扰动观测器的滑膜控制方法能够在固定时间内准确获取扰动的估计值,能够控制机械臂以高精度跟踪给定轨迹;通过与基于高阶扰动观测器的滑模控制方法进行仿真对比,验证了该方法在消除不确定扰动的基础上,能够有效地抑制系统抖振,并且跟踪误差能够在短时间内以指数速率完成收敛。     

电液伺服力控系统的自适应滑模控制

针对存在不确定性的非线性电液伺服力控系统的跟踪控制问题,基于等价控制的概念,提出了一种自适应滑模控制律综合方法,应用参数自适应的方法,消除不确定性对控制性能的影响,以达到鲁棒跟踪控制的目的。为了证明这种控制器可行性,利用微机实现的该控制器被应用于某疲劳试验机电液伺服系统,实时控制的结果验证了所提方法的有效性。     

基于MIMO滑模的气动伺服系统控制

针对非线性气动伺服系统的轨迹跟踪和柔顺控制问题,采用MIMO滑模控制器实现气动系统多输出的跟踪控制。对气动伺服系统基于流量控制策略的动力学进行建模,将其状态方程转换为严格反馈系统形式;设计用于轨迹跟踪和内腔压力跟踪的双滑模面,基于传统的滑模控制率构造用于气动系统的双控制输入,实现气动系统控制器的设计。基于Simulink搭建控制仿真平台,仿真结果验证了控制器对系统多输出的有效跟踪控制。     

双臂空间机器人捕获航天器后的镇定运动分块滑模自适应神经网络控制

讨论了双臂空间机器人捕获航天器后闭链混合体系统姿态和关节的受扰运动镇定控制及双臂协调操作问题。根据冲量定理及闭环约束条件,分析了双臂空间机器人捕获操作结束后受到的冲击效应,建立了闭链混合体系统动力学方程。以此为基础,针对星载计算机运算能力有限的问题,基于神经网络控制理论设计了分块滑模自适应控制方案。将混合体系统动力学方程考虑为多个非线性关联子系统的集合,因此可同时并行地利用神经网络来分别逼近各子系统未知动力学模型,即通过并行处理来提高计算效率。设计了自适应滑模控制器来抵消交联项及神经网络逼近误差的影响。为了保证各臂杆的协同操作,基于最小权值范数法分配了各臂关节控制力矩。通过系统数值仿真验证了所提控制方案的有效性。     

4自由度机械手的滑模变结构轨迹跟踪控制

针对机械手的高度非线性、强耦合的特性,依据滑模变结构控制理论,提出了一种机械手的滑模变结构的控制方法,并对其进行仿真。仿真结果证明该方法对4自由度机械手的轨迹跟踪的有效和准确性。     

Finite-time control for nonlinear spacecraft attitude based on terminal sliding mode technique

In this paper, a fast terminal sliding mode control (FTSMC) scheme with double closed loops is proposed for the spacecraft attitude control. The FTSMC laws are included both in an inner control loop and an outer control loop. Firstly, a fast terminal sliding surface (FTSS) is constructed, which can drive the inner loop tracking-error and the outer loop tracking-error on the FTSS to converge to zero in finite time. Secondly, FTSMC strategy is designed by using Lyaponov's method for ensuring the occurrence of the sliding motion in finite time, which can hold the character of fast transient response and improve the tracking accuracy. It is proved that FTSMC can guarantee the convergence of tracking-error in both approaching and sliding mode surface. Finally, simulation results demonstrate the effectiveness of the proposed control scheme.     

Fractional order nonsingular terminal sliding mode control for flexible spacecraft attitude tracking

This paper investigates a fractional terminal sliding mode control for flexible spacecraft attitude tracking in the presence of inertia uncertainties and extern...     

Feedback attitude sliding mode regulation control of spacecraft using arm motion

The problem of spacecraft attitude regulation based on the reaction of arm motion has attracted extensive attentions from both engineering and academic fields.Most of the solutions of the manipulator’s motion tracking problem just achieve asymptotical stabilization performance,so that these controllers cannot realize precise attitude regulation because of the existence of non-holonomic constraints.Thus,sliding mode control algorithms are adopted to stabilize the tracking error with zero transient process.Due to the switching effects of the variable structure controller,once the tracking error reaches the designed hyper-plane,it will be restricted to this plane permanently even with the existence of external disturbances.Thus,precise attitude regulation can be achieved.Furthermore,taking the non-zero initial tracking errors and chattering phenomenon into consideration,saturation functions are used to replace sign functions to smooth the control torques.The relations between the upper bounds of tracking errors and the controller parameters are derived to reveal physical characteristic of the controller.Mathematical models of free-floating space manipulator are established and simulations are conducted in the end.The results show that the spacecraft’s attitude can be regulated to the position as desired by using the proposed algorithm,the steady state error is 0.000 2 rad.In addition,the joint tracking trajectory is smooth,the joint tracking errors converges to zero quickly with a satisfactory continuous joint control input.The proposed research provides a feasible solution for spacecraft attitude regulation by using arm motion,and improves the precision of the spacecraft attitude regulation.     

Adaptive fast sliding mode fault tolerant control integrated with disturbance observer for spacecraft attitude stabilization system

In this paper, the problem of fault-tolerant control (FTC) for spacecraft attitude stabilization system with actuator fault and mismatched disturbance is investigated. A novel fault tolerant control strategy based on adaptive fast terminal sliding mode control (AFTSMC) is proposed. Firstly, a novel composite observer is proposed to estimate the disturbance, actuator efficiency factor and partial states of the system. By introducing a sliding mode observer, the bias actuator fault is reconstructed. Subsequently, in accordance with the estimated information, a novel sliding mode fault tolerant controller is designed. The proposed control scheme contains two compensators and two adaptive parameters to attenuate the mismatched disturbance, to compensate actuator fault, and to guarantee fast convergence of the system. Furthermore, the reachability of sliding motion is proved. The simulation results for the spacecraft system illustrate the effectiveness of the proposed method.     

Finite-time fault tolerant attitude stabilization control for rigid spacecraft

A sliding mode based finite-time control scheme is presented to address the problem of attitude stabilization for rigid spacecraft in the presence of actuator fault and external disturbances. More specifically, a nonlinear observer is first proposed to reconstruct the amplitude of actuator faults and external disturbances. It is proved that precise reconstruction with zero observer error is achieved in finite time. Then, together with the system states, the reconstructed information is used to synthesize a nonsingular terminal sliding mode attitude controller. The attitude and the angular velocity are asymptotically governed to zero with finite-time convergence. A numerical example is presented to demonstrate the effectiveness of the proposed scheme.     

Adaptive sliding mode current control with sliding mode disturbance observer for PMSM drives

This paper focuses on the current control of a permanent magnet synchronous motor (PMSM) for electric drives with model uncertainties and external disturbances. To improve the performance of the PMSM current loop in terms of the speed of response, tracking accuracy, and robustness, a hybrid control strategy is proposed by combining the adaptive sliding mode control and sliding mode disturbance observer (SMDO). An adaptive law is introduced in the sliding mode current controller to improve the dynamic response speed of the current loop and robustness of the PMSM drive system to the existing parameter variations. The SMDO is used as a compensator to restrain the external disturbances and reduce the sliding mode control gains. Experiments results demonstrate that the proposed control strategy can guarantee strong anti-disturbance capability of the PMSM drive system with improved current and speed-tracking performance.     

Attitude output feedback control for rigid spacecraft with finite-time convergence

The main problem addressed is the quaternion-based attitude stabilization control of rigid spacecraft without angular velocity measurements in the presence of external disturbances and reaction wheel friction as well. As a stepping stone, an angular velocity observer is proposed for the attitude control of a rigid body in the absence of angular velocity measurements. The observer design ensures finite-time convergence of angular velocity state estimation errors irrespective of the control torque or the initial attitude state of the spacecraft. Then, a novel finite-time control law is employed as the controller in which the estimate of the angular velocity is used directly. It is then shown that the observer and the controlled system form a cascaded structure, which allows the application of the finite-time stability theory of cascaded systems to prove the finite-time stability of the closed-loop system. A rigorous analysis of the proposed formulation is provided and numerical simulation studies are presented to help illustrate the effectiveness of the angular-velocity observer for rigid spacecraft attitude control.     

Nonlinear attitude control for a rigid spacecraft by feedback linearization

Attitude control laaw design for spacecraft large angle maneuvers is investigated in this paper. The feedback linearization technique is applied to the design of a nonlinear tracking control law. The output function to be tracked is the quaternion attitude parameter. The designed control law turns out to be a combination of attitude and attitude rate tracking commands. The attitude-only output function, therefore, leads to a stable closed-loop system following the given reference trajectory. The principal advantage of the proposed method is that it is relatively easy to produce reference trajectories and associated controller.     

Fuzzy surface-based sliding mode control

A new controller based on a combination of Sliding Mode Control and Fuzzy Logic is proposed. The conventional sliding surface is modified using a set of fuzzy rules. This combination confers controller robustness and flexibility. A neutralization process and a mixing process are used to compare the performance of the new controller to that of a conventional sliding mode controller and a PID controller.     

移动机器人的准滑模控制研究

基于滑模变结构控制理论,针对移动机器人这类非完整系统,提出了一种准滑模控制方法.该方法利用李雅普洛夫函数和指数趋近律方法,设计移动机器人的控制律,结合准滑模方法,使用饱和函数代替符号函数,以降低因采用滑模变结构控制方法而产生的抖振.运用所提出的方法设计了轮式移动机器人的控制系统并进行了仿真,仿真结果验证了所提出的控制策略的有效性,并且能够有效地降低系统的抖振.