轮式移动焊接机器人输出反馈线性化控制

针对目前基于运动学模型的焊缝跟踪控制已经不能满足焊缝跟踪的高精度要求的问题,以一种后两轮差速驱动的5自由度轮式移动焊接机器人为对象,给出其动力学模型及其输出反馈线性化的过程,并提出一种基于此动力学的轮式移动焊接机器人路径跟踪控制方法。建立轮式移动机器人具有非完整力学系统形式的动力学模型,并推导出对应的状态反馈精确线性化模型。在此线性化模型基础上,考虑机器人动力学模型参数的不确定性,利用滑模变结构控制方法来设计动力学控制规律,选取线性切换函数和指数趋近律,设计滑模变结构控制器。并利用Lyapunov稳定性理论证明系统的稳定性且跟踪误差收敛,满足了移动机器人的轨迹跟踪要求,且具有设计方法简单、鲁棒性强的特点。通过仿真验证所提控制律的有效性和正确性。     

多关节机械臂干扰观测器的自适应滑模控制

为了解决多关节机械臂在外部干扰和建模误差的轨迹跟踪问题,提出了多关节机械臂干扰观测器的机械臂自适应滑模控制方法.针对干扰信号,采用干扰观测器对可观测干扰进行观测,对于未观测到的干扰通过自适应律的设计进行估计补偿;针对机械臂控制系统中的抖振问题,采用新型趋近律来设计滑模控制律,以减小抖振影响;最后,利用李雅普诺夫函数验证了系统的稳定性.仿真结果表明,该方法不仅可以有效地削弱抖振问题,而且还可以克服外界干扰和建模误差带来的不确定性,同时保证了系统的鲁棒性.     

多关节机械臂干扰观测器的自适应滑模控制

为了解决多关节机械臂在外部干扰和建模误差的轨迹跟踪问题,提出了多关节机械臂干扰观测器的机械臂自适应滑模控制方法.针对干扰信号,采用干扰观测器对可观测干扰进行观测,对于未观测到的干扰通过自适应律的设计进行估计补偿;针对机械臂控制系统中的抖振问题,采用新型趋近律来设计滑模控制律,以减小抖振影响;最后,利用李雅普诺夫函数验证了系统的稳定性.仿真结果表明,该方法不仅可以有效地削弱抖振问题,而且还可以克服外界干扰和建模误差带来的不确定性,同时保证了系统的鲁棒性.     

多关节机械臂干扰观测器的自适应滑模控制

为了解决多关节机械臂在外部干扰和建模误差的轨迹跟踪问题,提出了多关节机械臂干扰观测器的机械臂自适应滑模控制方法.针对干扰信号,采用干扰观测器对可观测干扰进行观测,对于未观测到的干扰通过自适应律的设计进行估计补偿;针对机械臂控制系统中的抖振问题,采用新型趋近律来设计滑模控制律,以减小抖振影响;最后,利用李雅普诺夫函数验证了系统的稳定性.仿真结果表明,该方法不仅可以有效地削弱抖振问题,而且还可以克服外界干扰和建模误差带来的不确定性,同时保证了系统的鲁棒性.     

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.     

非完整轮式移动机器人反演滑模轨迹跟踪控制器设计

针对轮式移动机器人的轨迹跟踪问题,提出了一种反演滑模控制方法。采用PI型滑模面设计等效控制律,利用变速函数代替了符号函数得到切换控制律,并利用Lypunov定理证明了系统的稳定性。仿真结果表明了该方法的有效性和正确性,控制中出现的抖振现象得到改善,在外界干扰影响下,也具有良好的控制品质。     

非完整移动机械臂的自适应模糊滑模控制研究

针对四轮二连杆非完整移动机械臂的轨迹跟踪问题,设计了一种结合自适应模糊控制和滑模控制的控制策略。首先建立了系统包含未知动力学模型不确定性和外部扰动的动力学控制模型,然后基于反演技术设计了控制器;采用了模糊控制来逼近系统未知时变总体不确定性,并采用了自适应机制动态优化模糊系统控制参数,进一步采用了指数趋近律滑模控制消除模糊逼近误差的影响。研究结果表明:该控制器对系统总体不确定性进行了有效补偿,保证了移动机械臂在复杂不确定环境下的良好轨迹跟踪性能。     

风电叶片打磨机器人柔性末端终端滑模力控制

为了自适应叶片在磨削过程叶片曲率的变化,实现主被动磨削力控制。仿照人体肌肉组织,提出一种适用于电机驱动的直线型类串联弹性驱动器(SEA)安装于六自由度机械臂末端,以实现柔性输出。并建立了类SEA数学模型,在基于类SEA动力学模型的基础上,提出一种新型非奇异快速终端滑模滑模面和多幂次趋近率,并依据新型滑模面和多幂次趋近率设计了带扰动补偿的控制律。通过与传统终端滑模面、传统趋近率得到的控制律进行了磨削力跟踪对比仿真实验,结果表明新型非奇异终端滑模面和多幂次趋近率得到的控制律趋近平衡点速率更快,要求控制器输出较低,抗干扰能力更强。     

基于级联滑模控制的高精度光电跟踪与捕获

为了进一步提高光电跟踪系统的目标捕获和跟踪性能,提出了一种基于变增益趋近律的级联滑模控制方法。基于反双曲正弦函数和幂次项设计了新型变增益滑模趋近律,在提高滑模面趋近速度的同时抑制滑模抖振现象;基于变增益滑模趋近律设计速度环和位置环滑模控制器构成级联滑模控制,以提高系统的动态响应性能和鲁棒性,提高系统对目标的捕获能力和跟踪精度。最后,以某球形光电跟踪系统的方位轴作为控制对象,进行了传统级联PI控制和级联滑模控制方法的对比分析。实验结果表明,相比于传统级联PI控制,捕获速度为1(°)/s的目标时,级联滑模控制可以将目标捕获时间减小32%;跟踪等效最大速度为4(°)/s和最大加速度为2(°)/s 2的正弦引导信号,可将跟踪误差RMS值减小31%,采用级联滑模控制可有效提高跟踪系统的控制性能。     

轮式移动机器人的Back-stepping滑模模糊自适应轨迹跟踪控制

为提高两轮驱动轮式移动机器人轨迹跟踪控制的精度,依据轮式移动机器人的运动学和动力学方程,提出了一种具有全局渐进稳定性的控制方法。首先基于Back-stepping建立了轮式移动机器人的运动学控制器;其次通过滑模控制方法建立轮式移动机器人的动力学控制器;然后加入模糊控制系统调节滑模增益以削弱抖振;最后对系统的未知扰动建立自适应控制规律,并证明了其稳定性。以跟踪直线、圆、类正弦轨迹为例进行了仿真研究,验证了该控制方法的有效性。     

纵向打滑状态下轮式移动机器人轨迹跟踪控制

针对轮式移动机器人纵向打滑状态下滑动参数未知的轨迹跟踪控制问题,提出了一种轨迹跟踪控制方法。建立了纵向打滑状态下移动机器人的运动学模型,用滑动 参数表示左右轮的打滑程度;设计合适的滑模观测器对未知的滑动参数进行估计,并通过低通滤波器减少抖振对估计结果产生的影响;基于Lyapunov直接法设计轨迹跟踪控制律,并提出了一种根据控制系统的极点分布确定控制参数的方法。仿真结果验证了所提方法的准确性和有效性。     

Finite-time tracking control of nth-order chained-form non-holonomic systems in the presence of disturbances

This paper addresses the problem of finite-time tracking controller design for nth-order chained-form non-holonomic systems in the presence of unknown disturbances. To this aim, a generalized disturbance observer based controller is proposed and combined with a recursive terminal sliding mode approach which guarantees finite-time convergence of the disturbance observer dynamic. By introducing a time-varying transformation and introducing a new control law, the existence of the sliding around the recursive terminal sliding mode surfaces is guaranteed. Finally, the proposed approach is applied for a wheeled mobile robot with a fourth-order chained-form non-holonomic model. The simulation results demonstrate the desirable and robust tracking performance of the proposed approach in the presence of unknown disturbance.     

Target Tracking Algorithm Using Finite-time Convergence Smooth Second-order Sliding Mode Controller for Mobile Robots

Target tracking control for wheeled mobile robot (WMR) need resolve the problems of kinematics model and tracking algorithm.High-order sliding mode control is a valid method used in the nonlinear tracking control system,which can eliminate the chattering of sliding mode control.Currently there lacks the research of robustness and uncertain factors for high-order sliding mode control.To address the fast convergence and robustness problems of tracking target,the tracking mathematical model of WMR and the target is derived.Based on the finite-time convergence theory and second order sliding mode method,a nonlinear tracking algorithm is designed which guarantees that WMR can catch the target in finite time.At the same time an observer is applied to substitute the uncertain acceleration of the target,then a smooth nonlinear tracking algorithm is proposed.Based on Lyapunov stability theory and finite-time convergence,a finite time convergent smooth second order sliding mode controller and a target tracking algorithm are designed by using second order sliding mode method.The simulation results verified that WMR can catch up the target quickly and reduce the control discontinuity of the velocity of WMR.     

水下机械手分数阶积分滑模轨迹跟踪控制方法研究

针对未知有界外部干扰下水下机械手的轨迹跟踪问题,提出了一种分数阶积分滑模控制方法。该方法采用了基于分数阶积分滑模面的指数趋近律,考虑外部扰动,在模型中添加了外部扰动的近似估计项,使得系统可以实现快速收敛,且具有较强的抗干扰能力。利用李雅普诺夫理论证明了该方法的稳定性。对六自由度水下机械手的跟踪问题进行了仿真,结果表明,该控制方法具有良好的轨迹跟踪能力,且对外部干扰表现出良好的鲁棒性。     

High precision tracking control of a servo gantry with dynamic friction compensation

This paper is concerned with the tracking control problem of a voice coil motor (VCM) actuated servo gantry system. By utilizing an adaptive control technique combined with a sliding mode approach, an adaptive sliding mode control (ASMC) law with friction compensation scheme is proposed in presence of both frictions and external disturbances. Based on the LuGre dynamic friction model, a dual-observer structure is used to estimate the unmeasurable friction state, and an adaptive control law is synthesized to effectively handle the unknown friction model parameters as well as the bound of the disturbances. Moreover, the proposed control law is also implemented on a VCM servo gantry system for motion tracking. Simulations and experimental results demonstrate good tracking performance, which outperform traditional control approaches.     

基于微分几何的离合器接合过程速度跟踪滑模控制

针对离合器控制系统中存在的非线性、外部干扰和参数不确定问题,提出了基于微分几何的离合器接合过程速度跟踪滑模控制方法。考虑系统参数的不确定性和外界干扰等不确定因素,建立了单个离合器起步动力学模型;基于微分几何的反馈线性化方法,得出系统的控制律;采用基于趋近律的滑模控制方法,设计了存在不确定干扰的离合器控制系统滑模控制器。利用Lyapunov理论对系统的稳定性进行了证明。仿真结果表明该控制器使离合器接合过程的速度跟踪精度高,且鲁棒性好。     

Direct adaptive robust tracking control for 6 DOF industrial robot with enhanced accuracy

A direct adaptive robust tracking control is proposed for trajectory tracking of 6 DOF industrial robot in the presence of parametric uncertainties, external disturbances and uncertain nonlinearities. The controller is designed based on the dynamic characteristics in the working space of the end-effector of the 6 DOF robot. The controller includes robust control term and model compensation term that is developed directly based on the input reference or desired motion trajectory. A projection-type parametric adaptation law is also designed to compensate for parametric estimation errors for the adaptive robust control. The feasibility and effectiveness of the proposed direct adaptive robust control law and the associated projection-type parametric adaptation law have been comparatively evaluated based on two 6 DOF industrial robots. The test results demonstrate that the proposed control can be employed to better maintain the desired trajectory tracking even in the presence of large parametric uncertainties and external disturbances as compared with PD controller and nonlinear controller. The parametric estimates also eventually converge to the real values along with the convergence of tracking errors, which further validate the effectiveness of the proposed parametric adaption law.     

Model algorithm control for path tracking of wheeled mobile robots

This paper proposes a model algorithm control (MAC) method for the path tracking control of differentially steered wheeled mobile robots (WMRs) subject to nonholonomic constraints. The continuous dynamic model of the wheeled mobile robot is presented and used as the model to be controlled. The MAC controller is designed based on the sampled-data representation of the system. In this paper the case that there exists time delay in the control input is also considered. A time discretization method using the Taylor series and the zero-order-hold (ZOH) assumption is proposed to discretize the continuous dynamic model of the WMR. This time discretization method is especially useful in the case of the time delayed system. It can provide finite dimensional and more accurate discretized form model of the mobile robot with input time delay and convert it into a general nonlinear time discretized form to which the MAC controller can be applied. Simulations are conducted to show the performance and feasibility of the proposed control strategy. In these simulations the WMR is controlled to track two difference reference paths such as the “8” shape path and the circular path. The bounded inertial parameters uncertainties and some disturbance are also considered in the model of the control system.     

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.