不确定机械系统的二阶逼近模糊滑模控制

针对不确定机械系统,利用模糊逻辑系统的万能逼近特性对未知非线性函数建模,以便设计控制方法。基于一阶逼近精度的模糊逻辑系统需要足够多的模糊规则才能保证一定的逼近精度,然而规则数的增多必然导致计算量的增大,不利于实时控制。本文中设计了具有二阶逼近精度的模糊逻辑系统对机械系统中的非线性未知部分进行实时逼近,并结合鲁棒性能好的滑模控制对不确定机械系统进行轨迹跟踪控制。从仿真实验证明,具有二阶逼近精度的模糊系统可以以很少的规则高精度的逼近任意非线性函数,并以此为基础构成的模糊滑模控制器不仅可以达到所希望的控制精度,比起规则数量多得多的模糊滑模控制,甚至位置误差和速度误差更小,跟踪速度更快。故采用特殊隶属函数所设计的自适应模糊逻辑系统,解决了逼近精度和模糊规则数量之间的矛盾,为机械系统的高精度的实时控制提供了保证。     

基于死区补偿的码垛机械臂控制算法

针对码垛机械臂系统中存在死区特性影响控制精度的问题,提出一种基于模糊自适应的死区补偿算法.首先,根据死区非线性特性设计模糊死区补偿器对系统中的非线性环节进行补偿和控制;其次,利用模糊自适应算法对变量进行实时整定,从而使得轨迹跟踪误差趋于零;最后,借助MATLAB对理论结果实施验证.结果表明所提的控制算法具有良好的稳定性,与其他算法相比具有更高的动、静态性能和轨迹跟踪精度.     

输入受限的非完整移动机器人的自适应模糊控制

提出了一种非完整移动机器人饱和自适应模糊轨迹跟踪控制方法,该方法基于反演技术分别设计了系统的运动学控制器和动力学控制器。运动学控制器通过引入分流控制技术解决了初始速度跳变引起的控制量突变问题,动力学控制器利用饱和函数和受限控制参数实现了其有界力矩控制。自适应模糊控制器将模糊逻辑系统与自适应方法相结合,有效消除了常规方法难以解决的系统未知不确定性对系统的影响。通过Lyapunov直接法证明了该系统是收敛且渐进稳定的。仿真结果验证了所设计控制器的良好控制性能和强鲁棒性。     

电力机车永磁同步电机自适应模糊滑模控制

为研究牵引工况下电力机车永磁同步电机(PMSM)的转速控制精度,考虑轮轨接触不平顺及车体静载荷在轮对径向产生的未知时变负载转矩,建立了机车PMSM在d-q坐标系下的数学模型;针对该耦合非线性系统中存在的负载转矩,设计非线性转矩观测器对其实际值进行估计,对观测误差采用自适应模糊逻辑系统进行逼近;依据Lyapunov稳定性理论,构造了基于转矩观测器的自适应模糊滑模控制器。理论分析及仿真结果表明,机车PMSM闭环转速控制系统跟踪误差一致有界,转矩观测误差收敛于0。     

非线性时滞系统自适应模糊动态面控制

针对含完全未知时滞的不确定非线性系统的控制问题,提出了一种自适应模糊动态面控制方案.首先采用模糊逻辑系统逼近系统的未知时滞函数,进而用参考信号代换逼近器输入中的未知时滞信号,取消了对未知时滞常作的假设,摆脱了控制器构造对时滞假设条件的依赖性.模糊逼近和时滞代换产生的误差则采用自适应边界技术处理.基于Lyapunov-Krasovskii泛函,证明了闭环系统所有信号半全局一致最终有界,通过调节设计参数可以实现任意的跟踪精度.仿真实例进一步说明了该方案的可行性.     

时变漂角下USV直线路径跟踪控制器设计与验证

为了解决"蓝信"号无人水面艇在真实海洋环境中的直线路径跟踪的精确控制问题,在考虑到实际航行中存在时变漂角的情况下,设计并验证了一种基于LOS制导算法的无人水面艇直线路径跟踪控制方法。以"蓝信"号无人水面艇的操纵运动模型及辨识的参数为基础,将LOS制导算法与模糊自适应PID航向跟踪控制相结合,设计了一种考虑时变漂角的无人水面艇直线路径跟踪控制器,仿真结果验证了该方法的可行性。最后,通过蓝信号无人水面艇在大连海事大学凌水校区外部海域的实船实验,验证了该方法应用在实际工程中的正确性和有效性,降低了真实海洋环境下实际航迹跟踪过程中时变漂角对航迹跟踪控制精度的影响。     

一种弧焊机器人轨迹跟踪控制方法的研究

针对弧焊机器人动态特性中的非线性和不确定因素,对机器人的轨迹跟踪控制问题进行了研究。为提高跟踪精度和控制性能,提出一种基于高斯基模糊神经网络的轨迹跟踪控制方法。该方法以高斯基作为隶属函数,结合神经网络和模糊算法,设计了高斯基模糊神经网络控制器。采用非线性规划中的最速下降法对模糊神经网络进行自学习,能够在线调节隶属度函数的中心以及关节耦合权值,使得控制器具有更好的自学习与自适应能力。数值仿真结果表明该控制方法能高效地控制机器人的轨迹跟踪。     

时变信号频率跟踪的一种新自适应陷波器方法

针对频率、幅值和相位均发生变化的时变信号,现有自适应陷波器(ANF)频率估计方法存在信号频率跟踪精确性和稳定性不足的问题,为此提出了一种基于新误差函数的ANF时变信号频率跟踪方法,通过新误差函数改善自适应算法收敛至最优频率解的精度与速度,以提高时变信号频率跟踪的精确性和稳定性。给出了新误差函数分析结果,新ANF方法实现步骤和该频率估计方法的Cramer-Rao下限。通过计算与现有ANF的时变信号频率跟踪方法性能进行了比较分析,并针对科里奥利质量流量计时变信号进行了现场实验验证。结果表明,该方法具有收敛速度快、跟踪精度高、更接近Cramer-Rao下限和抗噪性好的优点。     

基于T-S模糊系统的漂浮基空间机器人关节协调运动的分散自适应滑模控制

针对载体位置和姿态均不受控的漂浮基空间机器人系统动力学方程难以预知的情况,提出了一种基于模糊逻辑系统的分散自适应滑模控制方案。利用第二类拉格朗日方法建立了空间机器人系统动力学方程。针对空间机器人的每一个自由度,将其动力学描述为分散交联子系统的集合。使用T-S模糊逻辑系统逼近子系统未知的动力学模型,然后设计自适应滑模控制器消除交联项和模糊逼近误差对轨迹跟踪性能的影响,并用Lyapunov理论证明控制器的稳定性。这种控制方法不需要预知系统动力学方程。数值仿真结果证实了该分散控制器的可靠性和有效性。     

基于补偿与模糊比例积分微分控制的凸轮刀系统定位研究

以四步切割机项目的凸轮刀系统为研究对象,针对比例阀存在较大死区、具有时变非线性特点,以及凸轮刀系统存在响应滞后等问题,基于补偿与模糊比例积分微分控制对凸轮刀系统的定位问题进行研究,提出将模糊比例积分微分控制与自适应死区补偿相结合的自适应控制方法。通过计算机软件搭建凸轮刀系统的仿真模型,设计加入自适应补偿的模糊比例积分微分控制器,并对凸轮刀系统的定位进行优化。通过试验对比确认,所提出的自适应控制方法对系统输出具有良好的校正作用,能够有效改善凸轮刀系统的定位性能。     

交流伺服系统自适应模糊滑模控制

介绍了交流伺服系统的自适应模糊滑模控制方案.通过自适应模糊控制解决了扰动补偿问题.正是因为结合了模糊控制的逼近特性和滑模控制的鲁棒性,才使得系统对外部扰动具有很好的稳定性和鲁棒性,同时消除了抖动现象.仿真实验表明这一控制方案具有很好的控制效果.     

A FUZZY UNCERTAINTY COMPENSATOR FOR MANIPULATOR TRAJECTORY TRACKING

A novel fuzzy logic compensating (FLC) scheme is proposed to enhance the conventional computed-torque control (CTC) structure of manipulators The control scheme is based on the combination of a classical CTC and FLC, and the resulting control scheme has a simple structure with improved robustness. Further improvement of the performance of the FLC scheme is achieved through automatic tuning of a weight parameter a leading to a self-tuning fuzzy logic compensator, so the system uncertainty can be compensated very well. By taking into account the full nonlinear nature of the robotic dynamics, the overall closed-loop system is shown to be asymptotically stable. Experimental results demonstrate the effectiveness of the computed torque and fuzzy compensation scheme to control a manipulator during a trajectory tracking task.     

Robust nonlinear PID-like fuzzy logic control of a planar parallel (2PRP-PPR) manipulator

In this paper, a robust nonlinear proportional–integral–derivative (PID)-like fuzzy control scheme is presented and applied to complex trajectory tracking control of a 2PRP-PPR (P-prismatic, R-revolute) planar parallel manipulator (motion platform) with three degrees-of-freedom (DOF) in the presence of parameter uncertainties and external disturbances. The proposed control law consists of mainly two parts: first part uses a feed forward term to enhance the control activity and estimated perturbed term to compensate for the unknown effects namely external disturbances and unmodeled dynamics, and the second part uses a PID-like fuzzy logic control as a feedback portion to enhance the overall closed-loop stability of the system. Experimental results are presented to show the effectiveness of the proposed control scheme.     

Modeling and control of the magnetic suspension system

A fuzzy logic based controller applied to a simple magnetic suspension is presented in this paper. The simple electromagnet-ball system and the contactless optical position measurement system are developed as a physical model of the magnetic suspension. A nonlinear mathematical model is presented and linearized. This model has been used to design a discrete linear PID controller with optimal parameters. The physical real-time model was constructed in order to compare the performance of the linear discrete PID controller and the proposed fuzzy logic based PID controller. The decomposed fuzzy PID controller has proportional, integral, and derivative separate parts which are tuned independently. When testing it becomes clear that the decomposed fuzzy PID controller gives better performance over a typical operational range than a traditional linear PID controller.     

天然气发电机组频率自适应模糊控制

为提高天然气发电机组交流频率的控制精度,提出了基于规则修改和比例因子自调整的自适应模糊频率控制方法．自适应模糊控制器通过改变误差和误差变化的权值来修改控制规则,根据机组负荷区域及负荷变化采用模糊决策调整比例因子．试验结果证明了自适应模糊频率控制的有效性和可行性．     

Adaptive fuzzy approach for a class of uncertain nonlinear systems in strict-feedback form

Adaptive fuzzy control is proposed for a class of affine nonlinear systems in strict-feedback form with unknown nonlinearities. The unknown nonlinearities include two types of nonlinear functions: one satisfies the "triangularity condition" and can be directly approximated by fuzzy logic system, while the other is assumed to be partially known and consists of parametric uncertainties. Takagi-Sugeno type fuzzy approximators are used to approximate unknown system nonlinearities and the design procedure is a combination of adaptive backstepping and generalized small gain design techniques. It is proved that the proposed adaptive control scheme can guarantee the uniformly ultimately bounded (UBB) stability of the closed-loop systems. Simulation studies are shown to illustrate the effectiveness of the proposed approach.     

Active surge control for variable speed axial compressors

This paper discusses active surge control in variable speed axial compressors. A compression system equipped with a variable area throttle is investigated. Based on a given compressor model, a fuzzy logic controller is designed for surge control and a proportional speed controller is used for speed control. The fuzzy controller uses measurements of the change of pressure rise as well as the change of mass flow to determine the throttle opening. The presented approach does not require the knowledge of system equilibrium or the surge line. Numerical simulations show promising results. The proposed fuzzy logic controller performs better than a backstepping controller and is capable to suppress surge at different operating points.     

挖掘机器人的模型与自适应模糊滑模控制

为实现挖掘机器人的自动挖掘,在挖掘机器人的轨迹规划器给出铲斗期望运动轨迹的情况下,需要挖掘机器人的控制系统能够控制其工作装置实现对给定轨迹的准确跟踪.利用拉格朗日方法建立了挖掘机器人工作装置的三自由度动力学方程,设计了自适应模糊滑模变结构控制器.利用模糊控制动态调节切换增益,将滑模控制的切换项转化为连续的模糊系统,增强了控制系统对挖掘机器人工作装置不确定性和外界干扰的鲁棒性,削弱了滑模控制的抖振现象,并且有较强的自适应跟踪能力.利用MATLAB7.4/Simulink工具箱对所设计的控制器进行了仿真,给出了自适应模糊滑模控制的跟踪性能及误差.     

Fuzzy logic sliding mode control for command guidance law design

Recently, the combination of sliding mode and fuzzy logic techniques has emerged as a promising methodology for dealing with nonlinear, uncertain, dynamical systems. In this paper, a sliding mode control algorithm combined with a fuzzy control scheme is developed for the trajectory control of a command guidance system. The acceleration command input is mathematically derived. The proposed controller is used to compensate for the influence of unmodeled dynamics and to alleviate chattering. Simulation results show that the proposed controller gives good system performance in the face of system parameters variation and external disturbances. In addition, they show the effectiveness of the proposed missile guidance law against different engagement scenarios where the results demonstrate better performance over the conventional sliding mode control.     

振动自适应模糊控制方法研究

将自适应模糊控制理论引入振动控制工程领域,提出了一种基于模糊逻辑系统的在线自学习控制方法。给出了该控制方法的学习算法及初始振动模糊控制器的产生方法。分析了该方法与其它非线性控制方法（神经网络控制）相比所具有的优点。仿真结果表明该自适应模糊控制方法能有效地抑制振动。