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122.
Manual monitoring and seam tracking through watching weld pool images in real-time, by naked eyes or by industrial TV, are experience-depended, subjective, labor intensive, and sometimes biased. So it is necessary to realize the automation of computer-aided seam tracking. A PAW (plasma arc welding) seam tracking system was developed, which senses the molten pool and the seam in one frame by a vision sensor, and then detects the seam deviation to adjust the work piece motion adaptively to the seam position sensed by vision sensor. A novel molten pool area image-processing algorithm based on machine vision was proposed. The algorithm processes each image at the speed of 20 frames/second in real-time to extract three feature variables to get the seam deviation. It is proved experimentally that the algorithm is very fast and effective. Issues related to the algorithm are also discussed. 相似文献
123.
R. Sarathi 《应用聚合物科学杂志》2002,83(13):2843-2849
In the present work tracking phenomena were studied with high‐density polyethylene (HDPE) materials under dc voltage, with NH4Cl and acid rain as contaminants. It was determined that the tracking time of the material depends on the conductivity and flow rate of the contaminant. Furthermore, physicochemical analysis by wide‐angle X‐ray diffraction studies, differential scanning calorimetry, and luminescence spectroscopy was carried out, whereupon it was concluded that the tracking process is a surface‐degradation process. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 2843–2849, 2002; DOI 10.1002/app.10260 相似文献
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125.
In this paper, a decentralized adaptive tracking control is developed for a second-order leader–follower system with unknown dynamics and relative position measurements. Linearly parameterized models are used to describe the unknown dynamics of a self-active leader and all followers. A new distributed system is obtained by using the relative position and velocity measurements as the state variables. By only using the relative position measurements, a dynamic output–feedback tracking control together with decentralized adaptive laws is designed for each follower. At the same time, the stability of the tracking error system and the parameter convergence are analyzed with the help of a common Lyapunov function method. Some simulation results are presented to validate the proposed adaptive tracking control. 相似文献
126.
《自动化学报》2014,(11)
A nonlinear control is proposed for trajectory tracking of a 6-DOF model-scaled helicopter with constraints on main rotor thrust and fuselage attitude. In the procedure of control design, the mathematical model of helicopter is simplified into three subsystems: altitude subsystem, longitudinal-lateral subsystem and attitude subsystem. The proposed control is developed by combining the sub-controls for the corresponding subsystems. The sub-controls for altitude subsystem and longitudinal-lateral subsystem are designed with hyperbolic tangent functions to satisfy the constraints; the sub-control for attitude subsystem is based on backstepping technique such that fuselage attitude tracks the virtual control for longitudinallateral subsystem. It is proved theoretically that tracking errors are ultimately bounded, and control constraints are satisfied.Performances of the proposed controller are demonstrated by simulation results. 相似文献
127.
针对迭代学习控制(Iterative learning control,ILC)中的初始状态问题,提出了采用有限时间跟踪微分器安排过渡过程方法,根据迭代学习控制中期望轨迹已知的特点,设计了其参数有明显物理意义并且调节方便的有限时间跟踪微分器. 在此基础上,针对一类具有不确定性的非线性时变系统的迭代学习控制问题,提出了具有对不确定项进行估计的迭代学习控制算法,并应用类Lyapunov方法给出了相关定理证明. 仿真结果表明所提出的方法是有效的. 相似文献
128.
基于硬件Kalman滤波器的航拍云台姿态获取 总被引:1,自引:0,他引:1
航拍云台姿态获取是航空摄影中相机姿态校正的基本依据,介绍了一种基于硬件Kalman滤波器的航拍云台姿态获取的实现方法。设计中采用MPU6050作为系统的姿态传感器,它提供三轴角速度和三轴加速度数据。根据系统特征建立Kalman滤波方程对这些数据进行数据融合处理,Kalman滤波过程中的加减乘除浮点数运算由FPGA实现,外部数据的采集和时序的控制也由FPGA完成。经过对实际数据的处理实验,得出该硬件模块可以获得较为准确的航拍云台姿态,输出结果误差在-1.5°~1.5°范围内。 相似文献
129.
《Automatica》2014,50(11):2737-2764
Adaptive control is a control methodology capable of dealing with uncertain systems to ensure desired control performance. This paper provides an overview of some fundamental theoretical aspects and technical issues of multivariable adaptive control, and a thorough presentation of various adaptive control schemes for multi-input–multi-output systems, literature reviews on adaptive control foundations and multivariable adaptive control methods, and related technical problems. It covers some basic concepts and issues such as certainty equivalence, stability, tracking, robustness, and parameter convergence. It discusses some of the most important topics of adaptive control: plant uncertainty parametrization, stable controller adaptation, and design conditions for different adaptive control schemes. The paper also presents a detailed study of well-developed multivariable model reference adaptive control theory and design techniques. It provides an introduction to multivariable adaptive pole placement and adaptive nonlinear control, and it concludes by identifying some open research problems. 相似文献
130.
Giuseppe Placidi Danilo Avola Marco Ferrari Daniela Iacoviello Andrea Petracca Valentina Quaresima Matteo Spezialetti 《Computer methods and programs in biomedicine》2014