In this paper, two improved projection algorithms are proposed for a servo turntable system based on the autoregressive exogenous (ARX) model. The improvement pertains to the complexity, convergence speed and estimati...
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In this paper, two improved projection algorithms are proposed for a servo turntable system based on the autoregressive exogenous (ARX) model. The improvement pertains to the complexity, convergence speed and estimation accuracy of the algorithm. First, the ARX model structure to be identified is obtained from the open -loop velocity model of the servo turntable. To solve the problems of imprecise step size calculation and slow convergence, the adaptive step size momentum projection (AMP) algorithm is proposed, in which segmented adaptive step sizes are adopted and momentum factors are introduced. On this basis, the latest estimation -based hierarchical adaptive step size momentum projection (LE -AMP) algorithm, which has faster convergence, is proposed as a combination of the hierarchical strategy and the latest estimation approach. Second, the complexity and convergence performance of the proposed algorithms are compared and analyzed. Finally, the effectiveness of the algorithms is verified using two examples. Theoretical analysis and simulation experiments show that the AMP algorithm has excellent parameter estimation accuracy, and its convergence speed is further improved through the addition of the momentum factor and the latest estimation, and these improved strategies do not cause any significant increase in complexity.
Dual-motor driving servo systems are widely used in many military and civil fields. Since backlash nonlinearity affects the dynamic performance and steady-state tracking accuracy of these systems, it is necessary to s...
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Dual-motor driving servo systems are widely used in many military and civil fields. Since backlash nonlinearity affects the dynamic performance and steady-state tracking accuracy of these systems, it is necessary to study a control strategy to reduce its adverse effects. We first establish the state-space model of a system. To facilitate the design of the controller, we simplify the model based on the state-space model. Then, we design an adaptive controller combining a projection algorithm with dynamic surface control applied to a dual-motor driving servo system, which we believe to be the first, and analyze its stability. Simulation results show that projection algorithm-based dynamic surface control has smaller tracking error, faster tracking speed, and better robustness and stability than mere dynamic surface control. Finally, the experimental analysis validates the effectiveness of the proposed control algorithm.
In this paper, the distributed containment control problem is studied for continuous-time fractional-order multi-agent systems. A distributed containment control protocol with nonlinear projection algorithm is designe...
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ISBN:
(纸本)9789881563972
In this paper, the distributed containment control problem is studied for continuous-time fractional-order multi-agent systems. A distributed containment control protocol with nonlinear projection algorithm is designed for each follower. Besides, a novel approach is proposed to show the effectiveness of the proposed containment control protocol. The main idea is to obtain the L-1 interpolation approximation of the investigated system based on piecewise linear interpolation, and then by using the property of the convex hull and the Mittag-Leffler function, we demonstrate that by taking the distributed containment control protocol, all followers can converge to the convex hull spanned by multiple leaders asymptotically. Finally, a numerical simulation is implemented to illustrate the effectiveness of the obtained theoretical results.
Permeable concrete is widely used as a road surfacing material due to its sturdiness and ability to be quickly repaired. The porosity of concrete has been used as a predictive indicator for the properties of the concr...
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Permeable concrete is widely used as a road surfacing material due to its sturdiness and ability to be quickly repaired. The porosity of concrete has been used as a predictive indicator for the properties of the concrete. Traditional methods for measuring this porosity are feasible but can be time-consuming. In this paper, we propose a particle swarm optimization-based projection algorithm for visualization of the high-dimensional data as a 2-D scatter plot for detecting porosity in permeable concrete from X-ray computerized tomography images. We regard the proposed projection algorithm as an improved version of Sammon's nonlinear mapping. The projected scatter plot allows for a straightforward analysis of the inherent structure of clusters within scanned images. Several data sets, including artificial data sets and real-life imaging data, were tested to demonstrate the performance of the proposed projection algorithm. The model created in this paper can augment the traditional methods for examining porosity by providing visual images for decision makers to make correct decisions for future problems. With an accuracy of >99%, the visualized images provide a clearer understanding of the inner structure of pervious concrete and enhance the study of the correlation between the properties of the concrete.
The problem of designing two feedback controllers for an unknown plant based on measured data is discussed here in a linear setting. Virtual reference feedback tuning control is a direct method that aims at minimizing...
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The problem of designing two feedback controllers for an unknown plant based on measured data is discussed here in a linear setting. Virtual reference feedback tuning control is a direct method that aims at minimizing a cost function of the 2-norm type by using a set of data. When constructing the cost function, we consider two model-matching problems between closed loop transfer function and sensitivity function simultaneously. In these model-matching procedures, we analyze how to design the reference input signal and disturb signal respectively. After transforming the problem of identifying unknown parameter vectors in virtual reference feedback tuning control into two linear regression models, the projection algorithm is introduced to achieve our first on-line parameter estimation scheme. And we also see that the projection algorithm is equivalent to one optimization problem. Further in this paper, scenario optimization is used to determine the number of scenarios that determine the solution. The maximum number of data points that determine the so-called support points equals the number of optimization variables.
Background: The need to organize any large document collection in a manner that facilitates human comprehension has become crucial with the increasing volume of information available. Two common approaches to provide ...
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Background: The need to organize any large document collection in a manner that facilitates human comprehension has become crucial with the increasing volume of information available. Two common approaches to provide a broad overview of the information space are document clustering and topic modeling. Clustering aims to group documents or terms into meaningful clusters. Topic modeling, on the other hand, focuses on finding coherent keywords for describing topics appearing in a set of documents. In addition, there have been efforts for clustering documents and finding keywords simultaneously. Results: We present an algorithm to analyze document collections that is based on a notion of a theme, defined as a dual representation based on a set of documents and key terms. In this work, a novel vector space mechanism is proposed for computing themes. Starting with a single document, the theme algorithm treats terms and documents as explicit components, and iteratively uses each representation to refine the other until the theme is detected. The method heavily relies on an optimization routine that we refer to as the projection algorithm which, under specific conditions, is guaranteed to converge to the first singular vector of a data matrix. We apply our algorithm to a collection of about sixty thousand PubMed (R) documents examining the subject of Single Nucleotide Polymorphism, evaluate the results and show the effectiveness and scalability of the proposed method. Conclusions: This study presents a contribution on theoretical and algorithmic levels, as well as demonstrates the feasibility of the method for large scale applications. The evaluation of our system on benchmark datasets demonstrates that our method compares favorably with the current state-of-the-art methods in computing clusters of documents with coherent topic terms.
In this paper, we propose a hybrid CQ projection algorithm with two projection steps and one Armijo-type line-search step for the split feasibility problem. The line-search technique is intended to construct a hyperpl...
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In this paper, we propose a hybrid CQ projection algorithm with two projection steps and one Armijo-type line-search step for the split feasibility problem. The line-search technique is intended to construct a hyperplane that strictly separates the current point from the solution set. The next iteration is obtained by the projection of the initial point on a regress region (the intersection of three sets). Hence, algorithm converges faster than some other algorithms. Under some mild conditions, we show the convergence. Preliminary numerical experiments show that our algorithm is efficient.
In this paper, we improve the convergence theorem in the paper by Yang (Journal of Industrial and Management Optimization 1, 211-217, 2005), and propose a new modified convergence theorem. The theorem and the proof pr...
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In this paper, we improve the convergence theorem in the paper by Yang (Journal of Industrial and Management Optimization 1, 211-217, 2005), and propose a new modified convergence theorem. The theorem and the proof presented in the present paper are interesting improvements on the convergence theorem of Yang.
Overset on viscous grid is an important application of overset grid method. The projection algorithm for viscous grid is a crucial algorithm of viscous grid overlapping and has been extended to the cell-centered syste...
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ISBN:
(纸本)9781467388290
Overset on viscous grid is an important application of overset grid method. The projection algorithm for viscous grid is a crucial algorithm of viscous grid overlapping and has been extended to the cell-centered system. Some special handling is done to enhance the robustness of the projection algorithm. A steady DLR-F6 wing body flow is performed, and good agreement of computational results with experimental data has been achieved, showing that this algorithm has a strong applicability to complex geometry.
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