An experimental printed circuit board drilling system automated by pattern recognition

The two-dimensional image processing necessary for closed-loop control of automated printed circuit board drilling and a mechanical prototype capable of drilling simulated printed-circuit boards are described. A single closed-loop correction of position permits correction of errors introduced by vidicon camera positional nonlinearity, noise, irregular lighting, inaccuracy of transformational constants, and mechanical slippage. These errors are corrected to an acceptable degree and in a short enough time that automatic drilling may present a challenge to manual drilling labor costs.     

Control of reactive distillation process for production of ethyl acetate

In this paper, plant-wide control for the production of ethyl acetate using reactive distillation is studied. Four important issues are considered in developing control schemes, including: (1) economics; (2) steady-state deviation of key product purities; (3) controllability in terms of degree of oscillation and settling time; and (4) feasible region of disturbances for effective control. Starting with two basic control schemes that have been studied before, new control schemes are developed to improve the operability of the process. These new control schemes have evolved from the basic schemes by making a trade-off between optimal design and control or by selecting sensor locations using closed-loop sensitivity analysis. It is found that, while being subjected to fluctuations in the composition of the acid feed or in the production flow-rate, sensor location based on traditional open-loop sensitivity causes a larger overshoot and steady-state deviation of key product purities. Sensor location on the basis of a closed-loop sensitivity analysis provides a better alternative for feedback control. The resulting scheme for control is found to be effective in reducing the steady-state deviation and in promoting good control performance.     

Adaptive fuzzy robust tracking controller design via small gain approach and its application

An adaptive fuzzy robust tracking control (AFRTC) algorithm is proposed for a class of nonlinear systems with the uncertain system function and uncertain gain function, which are all the unstructured (or nonrepeatable) state-dependent unknown nonlinear functions arising from modeling errors and external disturbances. The Takagi-Sugeno type fuzzy logic systems are used to approximate unknown uncertain functions and the AFRTC algorithm is designed by use of the input-to-state stability approach and small gain theorem. The algorithm is highlighted by three advantages: 1) the uniform ultimate boundedness of the closed-loop adaptive systems in the presence of nonrepeatable uncertainties can be guaranteed; 2) the possible controller singularity problem in some of the existing adaptive control schemes met with feedback linearization techniques can be removed; and 3) the adaptive mechanism with minimal learning parameterizations can be obtained. The performance and limitations of the proposed method are discussed. The uses of the AFRTC for the tracking control design of a pole-balancing robot system and a ship autopilot system to maintain the ship on a predetermined heading are demonstrated through two numerical examples. Simulation results show the effectiveness of the control scheme.     

一种基于SSVEP的仿人机器人异步脑机接口控制系统

设计了稳态视觉诱发电位(SSVEP)空闲状态检测的特征提取方法,建立了基于SSVEP的异步脑机接口二级分类器结构,开发了基于TICC2430芯片的无线传感器网络模块,实现了机器人控制命令的远程传送,使该仿人机器人系统具有脑电控制、语音交互、游戏手柄交互、机器视觉与避障等功能.通过SSVEP窄闲状态检测实验验证了脑机接口...     

基于串级PID和复合滤波算法板球控制系统设计

本文设计了一种基于串级PID算法和复合滤波的板球控制系统,通过多级错频获取速度差和位置差,并复合滑窗滤波和低通滤波算法,给出了以小球速度差为内环,位置偏差为外环的双闭环平衡控制策略,在simulink平台搭建了仿真模型并进行研究,同时利用J-Scope调试软件进行实际效果波形检测,结果表明本文设计应用的串级PID算法相对于经典单闭环位置式PID算法稳定性更强,系统稳态误差越小,添加复合滤波后,系统抖动明显减弱,位置控制更加精确,增强了板球控制系统实时控制动态响应效果。     

基于扩张状态观测器和反步滑模法的四旋翼无人机轨迹跟踪控制

为了解决欠驱动四旋翼无人机（UAV）在实际飞行中存在的外界干扰问题,同时提高在系统参数摄动情况下的精确轨迹跟踪效果,设计了一种基于扩张状态观测器（ESO）和积分型反步滑模算法的飞行控制策略。首先,根据系统的半耦合特性和严反馈结构特点,采用反步法设计姿态内环和位置外环控制器;然后,将抗干扰能力较强的滑模控制融入其中,使得系统的鲁棒性得到增强;接着,为了减小系统的稳态误差,引入积分环节;最后,利用ESO实时估算出系统的内、外总扰动并对控制量进行补偿。通过Lyapunov稳定判据,可以说明该系统是一个全局渐进稳定的系统,并通过仿真分析验证了所提控制方法的有效性和鲁棒性。     

A generalized function projective synchronization scheme for uncertain chaotic systems subject to input nonlinearities

In this paper, a modified generalized function projective synchronization scheme for a class of master–slave chaotic systems subject to dynamic disturbances and input nonlinearities (dead-zone and sector nonlinearities) is investigated. This synchronization system can be seen as a generalization of many existing projective synchronization schemes (namely the function projective synchronization, the modified projective synchronization and so on), in the sense that the master system has a scaling function matrix and the slave system has a scaling factor matrix. To practically achieve this generalized function synchronization, an adaptive fuzzy variable-structure control system is designed. The fuzzy systems are used to appropriately approximate the uncertain nonlinear functions. A Lyapunov approach is employed to prove the boundedness of all signals of the closed-loop control system as well as the exponential convergence of the synchronization errors to an adjustable region. Simulations results are presented to illustrate the effectiveness of the proposed generalized function PS scheme.     

电液系统位置压力非线性自适应双闭环控制

随着技术的不断发展电液伺服系统的用途越来越广泛,电液伺服系统在工业设备工程机械、冶金机械、机械制造等领域占据着举足轻重的地位.本文建立位置压力非线性自适应双闭环控制,通过李雅普诺夫函数算法的稳定性探索闭环系统的稳定性.通过李雅普诺夫函数逐步分析算法的半负定.根据半负定判定该算法的稳定性,若为半负定则此时的函数为渐近稳定的.若不是半负定则不是渐进稳定的.采用李雅普诺夫函数算法的稳定性的控制方法,可以使系统的误差逐渐减小,从而使系统趋于稳定状态.从结果分析可以看出采用非线性自适应双闭环控制对跟踪位置压力的期望值有明显的提高,并且误差值也越来越小.     

Consensus Control of Leader-Following Multi-Agent Systems in Directed Topology With Heterogeneous Disturbances

This paper investigates the consensus problem for linear multi-agent systems with the heterogeneous disturbances generated by the Brown motion. Its main contribution is that a control scheme is designed to achieve the dynamic consensus for the multi-agent systems in directed topology interfered by stochastic noise. In traditional ways, the coupling weights depending on the communication structure are static. A new distributed controller is designed based on Riccati inequalities, while updating the coupling weights associated with the gain matrix by state errors between adjacent agents. By introducing time-varying coupling weights into this novel control law, the state errors between leader and followers asymptotically converge to the minimum value utilizing the local interaction. Through the Lyapunov directed method and It? formula, the stability of the closed-loop system with the proposed control law is analyzed. Two simulation results conducted by the new and traditional schemes are presented to demonstrate the effectiveness and advantage of the developed control method.      

Adaptive motion control of wheeled mobile robot with unknown slippage

As a major representative nonholonomic system, wheeled mobile robot (WMR) is often used to travel across off-road environments that could be unstructured environments. Slippage often occurs when WMR moves in slopes or uneven terrain, and the slippage generates large accumulated position errors in the vehicle, compared with conventional wheeled mobile robots. An estimation of the wheel slip ratio is essential to improve the accuracy of locomotion control. In this paper, we propose an improved adaptive controller to allow WMR to track the desired trajectory under unknown longitudinal slip, where the stabilisation of the closed-loop tracking system is guaranteed by the Lyapunov theory. All system states use neural network online weight tuning algorithms, which ensure small tracking errors and no loss of stability in robot motion with bounded input signals. We demonstrate superior tracking results using the proposed control method in various Matlab simulations.     

Finite-Time Sideslip Differentiator-Based LOS Guidance for Robust Path Following of Snake Robots

This paper presents a finite-time sideslip differentiator-based line-of-sight (LOS) guidance method for robust path following of snake robots. Firstly, finite-time stable sideslip differentiator and adaptive LOS guidance method are proposed to counteract sideslip drift caused by cross-track velocity. The proposed differentiator can accurately observe the cross-track error and sideslip angle for snake robots to avoid errors caused by calculating sideslip angle approximately. In our method, the designed piecewise auxiliary function guarantees the finite-time stability of position errors. Secondly, for the case of external disturbances and state constraints, a Barrier Lyapunov function-based backstepping adaptive path following controller is presented to improve the robot’s robustness. The uniform ultimate boundedness of the closed-loop system is proved by analyzing stability. Additionally, a gait frequency adjustment-based virtual velocity control input is derived to achieve the exponential convergence of the tangential velocity. At last, the availability and superiority of this work are shown through simulation and experiment results.      

On tracking performance in bilateral teleoperation

This paper addresses the problem of steady-state position and force tracking in bilateral teleoperation. Passivity-based control schemes for bilateral teleoperation provide robust stability against network delays in the feedback loop and velocity tracking, but do not guarantee steady-state position and force tracking in general. Position drift due to data loss and offset of initial conditions is a well-known problem in such systems. In this paper, we introduce a new architecture, which builds upon the traditional passivity-based configuration by using additional position control on both the master and slave robots, to solve the steady-state position and force-tracking problem. Lyapunov stability methods are used to establish the range of the position control gains on the master and slave sides. Experimental results using a single-degree-of-freedom master/slave system are presented, showing the performance of the resulting system.     

Stable adaptive control for a class of nonlinear systems using amodified Lyapunov function

Investigates the adaptive control design for a class of nonlinear systems using Lyapunov's stability theory. The proposed method is developed based on a novel Lyapunov function, which removes the possible controller singularity problem in some of the existing adaptive control schemes using feedback linearization techniques. The resulting closed-loop system is proven to be globally stable, and the output tracking error converges to an adjustable neighborhood of zero     

欠驱动水下机器人三维轨迹跟踪有限时间预设性能控制

本文研究了具有不确定动态和未知时变海洋环境扰动的欠驱动水下机器人(AUVs)三维轨迹跟踪有限时间预设性能控制问题,提出新型预设性能函数和误差映射函数,将受预设性能限制的轨迹跟踪误差转变为非受限的变换后误差;构造新的超螺旋(ST)扩张状态观测器,在有限时间内实时估计AUV不确定动态和未知时变海洋环境扰动引起的总扰动;基于...     

基于2D三焦点张量的移动机器人视觉伺服镇定控制

针对单目视觉移动机器人系统, 本文提出了一种基于二维三焦点张量(2D trifocal tensor, 2DTT)的视觉伺服镇定控制方法. 具体而言, 首先描述了2D三焦点张量的导出过程, 并给出了基于图像特征点的估计方法. 在此基础上根据2D三焦点张量的元素, 设计了一种反馈线性化控制器以实现机器人的位置镇定, 以及一种比例控制器来实现姿态镇定, 因而在场景信息与平移信息均未知情况下完成了移动机器人的视觉镇定控制. 通过理论分析证明了本文设计的镇定控制算法具有指数收敛性能. 相比现有方法, 这种基于2D 三焦点张量的方法在图像特征识别方面具有更强的鲁棒性, 并且在平面场景与立体场景情况下均适用. 最后利用仿真与实验结果验证了本文提出的视觉伺服方法的优良性能.     

A concurrent design of input shaping technique and a robust control for high-speed/high-precision control of a chip mounter

Input Shaping Technique (IST) and Time Delay Control (TDC), a robust feedback control law, were combined to achieve fast and precise point-to-point motion of a chip mounter. TDC was used as a feedback control to overcome disturbances and parameter variations, an IST was used to suppress the residual vibration induced in the closed loop system. TDC was designed first for the machine, and a discrete version of IST was designed on the basis of the closed-loop dynamics. In the design of TDC, a better set of gains was available thanks to the use of IST than TDC alone; in the design of IST, too, a better design was possible than IST alone. As the result of the concurrent design and synergy of the two methods, point-to-point motion could be achieved with no overshoot, the settling time of about 0.05 s and few steady-state errors to position commands of 1.5 mm. This result is far better than a conventional PID control or TDC alone could achieve, thereby showing the effectiveness of the concurrent design.     

CAutoCSD – Evolutionary Search and Optimisation Enabled Computer Automated Control System Design

This paper attempts to set a unified scene for various linear time-invariant (LTI) control system design schemes, by transforming the existing concept of "computer-aided control system design" (CACSD) to novel "computer-automated control system design" (CAutoCSD). The first step towards this goal is to accommodate, under practical constraints, various design objectives that are desirable in both time and frequency domains. Such performance-prioritised unification is aimed at relieving practising engineers from having to select a particular control scheme and from sacrificing certain performance goals resulting from pre-commitment to such schemes. With recent progress in evolutionary computing based extra-numeric, multi-criterion search and optimisation techniques, such unification of LTI control schemes becomes feasible, analytical and practical, and the resultant designs can be creative. The techniques developed are applied to, and illustrated by, three design problems. The unified approach automatically provides an integrator for zero-steady state error in velocity control of a DC motor, and meets multiple objectives in the design of an LTI controller for a non-minimum phase plant and offers a high-performance LTI controller network for a non-linear chemical process.     

Robust consensus algorithm for second-order multi-agent systems with external disturbances

This article investigates the problem of robust consensus for second-order multi-agent systems with external disturbances. Based on a non-smooth backstepping control technique, a class of novel continuous non-smooth consensus algorithms are proposed for the multi-agent network with/without communication delays. The controller design is divided into two steps. First, for the kinematic subsystem, the velocity is regarded as a virtual input and designed such that the states consensus can be achieved asymptotically. Then for the dynamic subsystem, a finite-time control law is designed such that the virtual velocity can be tracked by the real velocity in a finite time. Under the proposed control law, it is shown that if the communication topology graph contains a directed spanning tree, the states consensus can be achieved asymptotically in the absence of disturbances. In the presence of disturbances, the steady-state errors of any two agents can reach a small region around the origin. By building a relationship between control parameters and the bound of steady tracking errors, it is demonstrated that the disturbance rejection performance of the resulting closed-loop system can be enhanced by adjusting the fractional power in the non-smooth controller. Finally, an example is given to verify the efficiency of the proposed method.     

Markov 系统矩阵未知情况下的控制器设计

针对Markov 系统矩阵参数未知的实际情况, 提出一种基于状态反馈控制与自适应控制相结合的控制方法. 基于线性矩阵不等式技术给出相应控制器参数的求解条件. 与现有大多数自适应控制方法相比, 所提方法不仅使估计误差几乎处处有界, 而且原系统的系统状态几乎处处渐近稳定, 具有较好的收敛特性. 在所得结果的基础上, 进一步讨论了转移速率部分未知时的相关控制问题. 数值算例验证了所提出的设计方法的有效性.

     

高超声速飞行器指定时间自适应控制

为了解决高超声速飞行器纵向运动模型的稳定轨迹跟踪控制问题,设计一种指定时间自适应控制方法.通过引入障碍李雅普诺夫函数,保证速度跟踪误差和高度跟踪误差能够收敛到期望的区域,同时满足系统的瞬态性能和稳态精度.将自适应控制与实际指定时间稳定理论结合,实现闭环系统在指定时间稳定,收敛时间可根据实际需求预先指定.引入的固定时间滤波器对虚拟导数进行求解,可以避免传统反步控制中存在的“计算爆炸”问题,提高收敛速度.对所设计的控制器利用李雅普诺夫理论给出严格理论证明,并能够保证系统其他状态变量在指定时间内趋于稳态值.仿真结果表明,所设计的控制器能够使速度和高度稳定地跟踪参考信号,满足时变的性能约束需求且具有较强的鲁棒性.