快速终端滑模控制在并联机器人中的应用

针对二自由度冗余驱动并联机器人,提出了并联机器人的快速终端滑模控制(FTSMC)以实现其鲁棒控制,并利用Lyapunov函数证明了该控制系统的稳定性。仿真结果表明,该控制系统跟踪效果好,系统误差小,可以满足并联机器人控制的要求。与采用普通滑模控制相比,该控制系统具有状态响应速度快,系统状态在有限时间内收敛到零的特点。仿真实验证实了该控制策略的正确性和有效性。     

主动悬架H_∞/广义H_2积分切换面自适应滑模控制研究

悬架是车轮与车辆承载系统之间的弹性连接装置的统称,是现代车辆重要组成部分之一。以四分之一汽车动力学模型作为研究对象,设计一种带有积分切换面的自适应滑模控制器。所设计的H∞/广义H2积分型切换面能够有效地改善悬架系统的动态性能,使其对非匹配外界路面扰动具有不敏感性。并且通过设计一种自适应律,实现对不确定路面扰动的辨识估计,提高了系统的实用性。将控制器的性能与被动悬架系统、H∞/广义H2主动悬架进行了对比,仿真结果证实了控制器的有效性。     

RBF神经网络滑模变结构控制在并联机器人中的应用

并联机器人系统结构复杂,具有强耦合、非线性等特点。滑模变结构控制对参数不确定性和外部扰动具有强鲁棒性,不需要被控对象精确数学模型且基于该方法的控制器设计过程是自然解耦过程,适用于并联机器人控制,但是滑模控制普遍存在抖振问题。鉴于此,该文提出RBF神经网络与滑模控制相结合的控制方法,利用RBF神经网络对滑模控制器切换项的增益进行调节,可以有效地降低滑模控制的抖振,获得较好的控制效果。仿真结果表明,该控制方法跟踪性能好,系统误差小,具有较强的鲁棒性,可以满足并联机器人的控制要求。     

六自由度并联机器人线性化反馈RBF神经滑模控制研究

采用分散控制的策略和线性化反馈RBF神经滑模的控制算法,实现了对六自由度并联机器人高精度自适应的轨迹跟踪控制。所设计的控制器实现了控制实时性和自适应性,有效抑制了滑动模态的抖振,仿真结果和实际实验均验证了此方案的实效性。     

基于交流伺服电机驱动的并联机器人动态滑模控制

并联机器人具有刚度大、承载能力强、误差小等特点,针对以交流伺服电机驱动的并联机器人机构--GPM-200并联机构,建立了控制系统模型,并在其工作空间中进行了轨迹规划,而后设计了一种动态滑模控制算法,在Matlab/Simulink上进行了仿真实验,结果表明:该算法鲁棒性好,且系统抗干扰能力强,对系统参数变化不敏感,具有良好的跟踪性能,实现了对该并联机器人的高精度实时控制.     

自适应反演神经网络控制在并联机器人中的应用

针对未知非线性、外界干扰等各种不确定因素对二自由度冗余并联机器人控制系统的影响,提出了反演自适应神经网络控制方法.RBF神经网络实现了不确定性函数的逼近,自适应反演控制作为主控制器完成并联机器人控制系统的输出.仿真结果表明,自适应反演神经网络控制方法跟踪性能好,系统误差小,具有很强的鲁棒性,能够满足并联机器人的控制要求.仿真实验证实了该控制策略的正确性和有效性.     

并联机器人的新型趋近率滑模控制研究

对一种驱动冗余四自由度并联机器人进行任务空间实时控制动力学滑模控制研究。基于所构建动力学模型,在任务空间内,提出并设计一种新型加权积分增益型指数趋近率滑模控制方法,利用滑动模态的形成,使控制系统对于不确定参数以及外界干扰具有良好的鲁棒性,同时,通过在趋近率的积分项中引入负的加权值,在保证并联机器人系统轨迹跟踪速度和精度的同时,有效降低起始阶段控制力的幅度并有效削弱输出驱动力的抖振。其次,利用Lyapunov函数,理论证明所设计控制律的稳定性。最后,利用MATLAB对所建立并联机器人动力学模型及所设计控制律进行仿真试验研究,通过与计算力矩控制、一般趋近率滑模控制进行仿真对比,其结果表明了所建立并联机器人动力学模型的实时可控性以及所设计控制方法的有效性。     

智能扫地机器人双环积分滑模控制方法研究

针对Mecanum轮型扫地机器人在车轮打滑和重心偏移等不确定非线性因素影响下的轨迹跟踪精度问题,提出了一种基于修正动力学模型的轨迹跟踪控制方法。首先,对机器人进行了运动学与动力学分析。然后,根据外界干扰及参数估计的不确定性对动力学模型进行了修正,设计了双环积分滑模控制器,并通过Lyapunov函数证明了控制系统的稳定性。最后,在不同扰动作用下,以圆为参考轨迹进行跟踪仿真,结果表明:该控制系统具有较好的抗干扰性和鲁棒性,避免了因不确定性参数估计带来的建模误差,为扫地机器人在实际轨迹跟踪控制运用中奠定了理论基础。     

并联机器人的智能模糊滑模控制算法

针对以交流伺服电机驱动的二自由度并联机器人,设计了智能模糊滑模控制算法.该方法先设计动态滑模面,使系统的任意初始状态一开始就在滑模面上,消除了滑模控制的到达运动阶段,使系统在响应的全过程都具有鲁棒性;然后设计一种智能模糊控制器,用模糊控制器的输出取代滑模控制切换项的输出.仿真结果表明,该控制方法不仅增强了全局抗干扰能力,而且有效地消除了系统的抖振现象.     

Adaptive fuzzy sliding mode control for an automatic arc welding system

This paper describes an automatic welding control system developed for alternating current shielded metal arc welding (SMAW). This method could replace manual operations which require a well-trained technician. We have derived a mathematical model of the welding control system and identified the system’s parameters. The sliding surface is used as the input variable to reduce the number of fuzzy reasoning rules, in comparison with the conventional two-dimensional fuzzy logic control (FLC) algorithm. An adaptive fuzzy sliding mode controller (AFSMC) consists of an equivalent control part and a hitting control part. An adaptive law derived from a Lyapunov function is used to obtain the FLC’s parameters, and is applied to approximate the equivalent control part of the sliding mode control (SMC), so that the system states can be forced to zero. By using three-rules FLC, the control part that satisfies the hitting conditions of the SMC can force the system’s states to reach and remain on the sliding surface. Therefore, the stability of the AFSMC can be guaranteed and can be used to modulate the rate of the electrode feeding mechanism that regulates the arc current of the SMAW. The simulation and the experimental results both show that this automatic welding control system, based on the AFSMC, can perform effectively.     

Adaptive fuzzy sliding mode control for an automatic arc welding system

This paper describes an automatic welding control system developed for alternating current shielded metal arc welding (SMAW). This method could replace manual operations which require a well-trained technician. We have derived a mathematical model of the welding control system and identified the system’s parameters. The sliding surface is used as the input variable to reduce the number of fuzzy reasoning rules, in comparison with the conventional two-dimensional fuzzy logic control (FLC) algorithm. An adaptive fuzzy sliding mode controller (AFSMC) consists of an equivalent control part and a hitting control part. An adaptive law derived from a Lyapunov function is used to obtain the FLC’s parameters, and is applied to approximate the equivalent control part of the sliding mode control (SMC), so that the system states can be forced to zero. By using three-rules FLC, the control part that satisfies the hitting conditions of the SMC can force the system’s states to reach and remain on the sliding surface. Therefore, the stability of the AFSMC can be guaranteed and can be used to modulate the rate of the electrode feeding mechanism that regulates the arc current of the SMAW. The simulation and the experimental results both show that this automatic welding control system, based on the AFSMC, can perform effectively.     

Second-order integral sliding-mode control with experimental application

In the present study, a second-order sliding-mode controller is proposed for single-input single-output (SISO) uncertain real systems. The proposed controller successively overcomes the variations caused by the uncertainties and external load disturbances although an approximate model of the system is used in the design procedure. An integral type sliding surface is used and the stability and robustness properties of the proposed controller are proved by means of Lyapunov stability theorem. The chattering phenomenon is significantly reduced adopting the switching gain with the known parameters of the system. Thus, the proposed controller is suitable for long-term application to the real systems. The performance of the proposed control scheme is validated by a real system experiments and the results are compared with the similar controllers presented in the literature.     

An enhanced tracking control of marine surface vessels based on adaptive integral sliding mode control and disturbance observer

In this paper, a new control methodology is developed to enhance the tracking performance of fully actuated surface vessels based on an integrating between an adaptive integral sliding mode control (AISMC) and a disturbance observer (DO). First, an integral sliding mode control (ISMC), in which the backstepping control technique is used as the nominal controller, is designed for the system. The major features, i.e., benefits and drawbacks, of the ISMC are discussed thoroughly. Then, to enhance the tracking performance of the system, an adaptive technique and a new disturbance observer based on sliding mode technique are developed and integrated into the ISMC. The stability of the closed-loop system is proved based on Lyapunov criteria. Computer simulation is performed to illustrate the tracking performance of the proposed controller and compare with the existing controllers for the tracking control of a surface vessel. The simulation results demonstrate the superior performance of the proposed strategy.     

Sliding mode control with PID sliding surface and experimental application to an electromechanical plant

In this study, a sliding mode control system with a proportional+integral+derivative (PID) sliding surface is adopted to control the speed of an electromechanical plant. A robust sliding mode controller is derived so that the actual trajectory tracks the desired trajectory despite uncertainty, nonlinear dynamics, and external disturbances. The proposed sliding mode controller is chosen to ensure the stability of overall dynamics during the reaching phase and sliding phase. The stability of the system is guaranteed in the sense of the Lyapunov stability theorem. The chattering problem is overcome using a hyperbolic function for the sliding surface. Experimental results that are compared with the results of conventional PID verify that the proposed sliding mode controller can achieve favorable tracking performance, and it is robust with regard to uncertainties and disturbances.     

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.