内模控制系统鲁棒跟踪控制器的参数化及优化

针对最常用的2自由度内模控制系统,利用基于传递函数互质分解的频域理论,推导了存在模型失配且参考输入和扰动为任意已知函数时,所有能实现稳态无差跟踪的前馈控制器和反馈滤波器的参数化表达式.所得结论同时适用干连续和离散时间系统,并可在参数化基础上实现频域的优化控制.     

基于互质因子摄动的反馈系统的鲁棒稳定性

考虑对象和控制器同时具有互质因子摄动时闭环系统的鲁棒稳定性问题,得到了闭环系统鲁棒稳定的充要条件并给出了鲁棒控制器的优化设计方法.     

关于自适应控制系统的鲁棒稳定性条件

本文用统一的方法对于由自适应控制系统的鲁棒稳定性分析提出的一类时变动态系统的有界解问题给出了一个充分条件。它为鲁棒自适应控制器的设计以及进行相应的理论分析带来了方便。     

基于鲁棒右互质分解的直流伺服系统精确跟踪控制

对含有不确定性的直流伺服控制系统,通过应用鲁棒右互质分解方法,设计了一种基于鲁棒右互质分解的精确跟踪控制系统;通常情况下,直流伺服系统中存在诸如非线性特性及参数辨识引起的模型误差和外界扰动,在设计的控制系统中,未知模型误差和外界扰动对系统性能的影响都被看作直流伺服系统的不确定性;在考虑到这些不确定性情况下,设计了一种基于鲁棒右互质分解理论的精确跟踪控制;首先在考虑未知的不确定模型影响系统性能指标的情况下,设计了一种基于演算子理论的反馈控制结构,此结构可以消除不确定模型的影响,在此基础上,设计了基于鲁棒右互质分解的鲁棒精确跟踪控制系统,得出精确跟踪条件;仿真结果表明使用提出的方法可以有效地消除不确定性,使得伺服系统具有很强的鲁棒性和精确跟踪能力。     

光电跟踪系统视轴稳定的鲁棒内模控制器设计

针对运动平台上光电跟踪系统既要抑制平台扰动对视轴稳定的影响,又必须对建模误差具有很强的鲁棒性的特点,设计了稳定平台改进鲁棒性的内模控制器。通过在内模控制基础上添加一局部反馈回路构成鲁棒内模控制,并详细分析了鲁棒内模控制对系统建模误差和外界扰动的鲁棒性。仿真和实验结果显示,与采用PI控制相比,鲁棒内模控制在很宽频段范围内提高了系统对扰动的抑制能力,28 Hz以内都有10 dB以上的提高。     

衰减扰动下非线性预测控制系统的鲁棒稳定性

考虑一般形式的非线性预测控制系统,研究带终端约束的稳定预测控制策略在衰减扰动下的鲁棒稳定性问题,首先引入离散非线性系统的输入状态稳定性,然后针对上述预测控制策略得出了系统的稳定性结论。     

机器人鲁棒模型跟踪控制

本文根据非线性系统模型参考控制理论,提出了一种连续的机器人控制方法.这种方法可以保证跟踪误差的有界性,消除不连续控制中的高频颤动现象,同时继承了不连续控制中的鲁棒特性。     

连续状态模糊控制系统的鲁棒稳定性分析

1　引言关于模糊系统的稳定性研究 ,目前已有许多相关的分析和设计方法 [1 ] .比如 ,文献 [2 ]中证明了凡用经典控制能稳定控制的系统必可用模糊控制达到相同的稳定性能 ,文献 [3]中有关 Takagi- Sugeno模糊系统的稳定性研究 ,文献 [4 ]中有关关系模型的模糊稳定性分析 ,文献 [     

不确定性线性系统的鲁棒渐近跟踪控制

对于线性不确定系统，本文给出了一种鲁棒渐近跟踪控制的设计方法，通过选取矩阵φ，构造广义匹配条件，利用Riccati方程正解给出了设计鲁棒渐近跟踪有效方法，对于匹配系统和不匹配系统均可使输出渐近跟踪某一参考输入，算例表明了该方法的有效性。     

参数不确定机器人分散鲁棒跟踪控制

提出了一种新的参数不确定机器人分散控制器设计方法．首先将关节子系统的动力学模型分解为人工标称模型和非线性时变不确定模型两部分；然后分别设计相应的标称控制器和鲁棒补偿器．标称控制器使得标称闭环系统具有理想的跟踪性能；鲁棒补偿器可以抑制参数不确定和关节间非线性耦合等因素的影响，实现鲁棒跟踪．所设计的控制器只需要局部关节的位置反馈，具有易于实现和可在线调整的优点．仿真结果说明了该方法的有效性．     

论两种改进内模控制系统的等价性

改进型内模控制有两种最常见的形式,针对这两种改进内模控制的研究一直认为它们是两种不同的控制,且其中一种比另一种更为优越.通过深入分析可以证明它们事实上是完全等价的,而且所得等价性结论具有一般性,无论采用何种设计方法、系统连续或离散、对象稳定与否都成立.     

Maximum sensitivity based fractional IMC–PID controller design for non-integer order system with time delay

A simple approach with a small number of tuning parameters is a key goal in fractional order controller design. Recently there have been a number of limited attempts to bring about improvements in these areas. In this paper, a new design method for a fractional order PID controller based on internal model control (IMC) is proposed to handle non-integer order systems with time delay. In order to reduce the number of tuning parameters and mitigate the impact of time delay, the fractional order internal model control scheme is used. Considering the robustness of the control system with respect to process variations and model uncertainty, maximum sensitivity is applied to the tuning of the parameters. The resulting controller has the structure of a fractional order PID which is cascaded with a filter. This is named a fractional IMC–PID controller. Numerical results are given to show the efficiency of the proposed controller.     

An intelligent robust tracking control for electrically-driven robot systems

This article addresses the problem of designing intelligent robust tracking controls of robot systems actuated by brushed direct current motors. The structures of both mechanical and electrical dynamics are allowed to be completely unknown and adaptive fuzzy (or neural network) systems are employed to approximate these two uncertainties. Consequently, an adaptive fuzzy-based (or neural network-based) state feedback tracking controller is developed such that the resulting closed-loop system guarantees that all the states and signals are bounded and the tracking error can be made as small as possible. Finally, simulation examples are made to demonstrate the effectiveness and tracking performance.     

IMC design for unstable processes with time delays

A modified IMC structure is proposed for unstable processes with time delays. The structure extends the standard IMC structure for stable processes to unstable processes and controllers do not have to be converted to conventional ones for implementation. An advantage of the structure is that setpoint tracking and disturbance rejection can be designed separately. A method is proposed to tune the modified IMC structure with an emphasis on the robustness of the structure. Design for some typical delayed unstable processes shows that the control structure can be tuned easily and achieve good tradeoff between time-domain performance and robustness.     

A modified direct adaptive robust motion trajectory tracking controller of a pneumatic system

In this study, we developed and tested a high-precision motion trajectory tracking controller of a pneumatic cylinder driven by four costless on/off solenoid valves rather than by a proportional directional control valve. The relationship between the pulse width modulation （PWM） of a signal＇s duty cycle and control law was determined experimentally, and a mathematical model of the whole system established. Owing to unknown disturbances and unmodeled dynamics, there are considerable uncertain nonlinearities and parametric uncertainties in this pneumatic system. A modified direct adaptive robust controller （DARC） was constructed to cope with these issues. The controller employs a gradient type adaptation law based on discontinuous projection mapping to guarantee that estimated unknown model parameters stay within a known bounded region, and uses a deterministic robust control strategy to weaken the effects of unmodeled dynamics, disturbances, and parameter estimation errors. By using discontinuous projection mapping, the parameter adaptation law and the robust control law can be synthesized separately. A recursive backstepping technology is applied to account for unmatched model uncertainties. Kalman filters were designed sepa- rately to estimate the motion states and the derivative of the intermediate control law in synthesizing the deterministic robust control law. Experimental results illustrate the effectiveness of the proposed controller.     

LMI conditions for quadratic and robust D-stability of interval systems

Sufficient conditions for the quadratic D-stability and further robust D-stability of interval systems are presented in this paper. This robust D-stability condition is based on a parameter-dependent Lyapunov function obtained from the feasibility of a set of linear matrix inequalities （LMIs） defined at a series of partial-vertex-based interval matrices other than the total vertex matrices as in previous results. The results contain the usual quadratic and robust stability of continuous-time and discrete-time interval systems as particular cases. The illustrative example shows that this method is effective and less conservative for checking the quadratic and robust D-stability of interval systems.     

Real-time edge-enhanced dynamic correlation and predictive open-loop car-following control for robust tracking

We present a robust framework for a real-time visual tracking system, based on a BPNN-controlled fast normalized correlation (BCFNC) algorithm and a predictive open-loop car-following control (POL-CFC) strategy. The search for the target is carried out in a dynamically generated resizable search-window. In order to achieve the robustness, we use some edge-enhancement operations before the correlation operation, and introduce an adaptive template-updating scheme. The proposed tracking algorithm is compared with various correlation-based techniques and (in some cases) with the mean-shift and the condensation trackers on real-world scenarios. A significant improvement in efficiency and robustness is reported. The POL-CFC algorithm approximates the current velocity of an open-loop pan-tilt unit, computes the predicted relative-velocity of the object using Kalman filter, and generates the precise control signals to move the camera accurately towards the maneuvering target regardless of its changing velocity. The proposed system works in real-time at the speed of 25–200 frames/ second depending on the template size, and it can persistently track a distant or near object even in the presence of object fading, low-contrast imagery, noise, short-lived background clutter, object-scaling, changing object-velocity, varying illumination, object maneuvering, multiple objects, obscuration, and sudden occlusion.     

Decentralised cooperative attitude tracking using modified Rodriguez parameters based on relative attitude information

In this article, the problem of decentralised cooperative attitude tracking based on relative attitude information is considered in the context of deep space spacecraft formation flying. We use modified Rodriguez parameters for attitude representation due to its nonreduction. We first present a distributed sliding-mode estimator and a cooperative attitude tracking control law such that the attitudes and angular velocities of all spacecraft track their references. Then we extend the result to three different cases. In the first case, we use a passivity approach to derive a control law without angular velocity measurements, which is of significance for applications with low-cost configurations of spacecraft. In the second case, to relax the special connectivity condition given in the original control design, we obtain a locally asymptotical stability condition for any undirected connected communication topology. In the third case, we consider cooperative attitude tracking in the presence of a dynamic communication topology. Simulation results are presented to validate the effectiveness of these control laws.     

A strong tracking nonlinear robust filter for eye tracking

Non-intrusive methods for eye tracking are important for many applications of vision-based human computer interaction. However, due to the high nonlinearity of eye motion, how to ensure the robustness of external interference and accuracy of eye tracking pose the primary obstacle to the integration of eye movements into today’s interfaces. In this paper, we present a strong tracking unscented Kalman filter (ST-UKF) algorithm, aiming to overcome the difficulty in nonlinear eye tracking. In the proposed ST-UKF, the Suboptimal fading factor of strong tracking filtering is introduced to improve robustness and accuracy of eye tracking. Compared with the related Kalman filter for eye tracking, the proposed ST-UKF has potential advantages in robustness and tracking accuracy. The last experimental results show the validity of our method for eye tracking under realistic conditions.