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Accuracy analysis of predicted velocity profiles of laminar duct flow with entropy generation method

应用数学和力学 2013年第8期 971-984页

作者： J. A. ESFAHANI M. MODIRKHAZENI S. MOHAMMADI Center of Excellence on Modeling and Control Systems CEMCS& Department of Mechanical Engineering Faculty of Engineering Ferdowsi University of Mashhad Mashhad 91775-1111 Iran

The objective of this work is to estimate the accuracy of a predicted velocity profile which can be gained from experimental results, in comparison with the exact ones by the methodology of entropy generation. The analysis is concerned with the entropy generation rate in hydrodynamic, steady, laminar, and incompressible flow for Newtonian fluids in the insulated channels of arbitrary cross section. The entropy generation can be calculated from two local and overall techniques. Adaptation of the results of these techniques depends on the used velocity profile. Results express that in experimental works, whatever the values of local and overall entropy generation rates are close to each other, the results are more accuracy. In order to extent the subject, different geometries have been investigated. Also, the influence of geometry on the entropy generation rate is studied, and the distribution of volumetric local entropy generation rate for the selected geometries is drawn.

关键词： entropy generation velocity profile duct arbitrary cross section laminar internal flow

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control Design of Flight Simulation Turntable Based on Model-Free Adaptive control

Control Design of Flight Simulation Turntable Based on Model...

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2023 China Automation Congress, CAC 2023

作者： Yue, Mingtan Zhang, Yu Huo, Xin Control & Simulation Center Harbin Institute of Technology Harbin150080 China Beijing Simulation Center National Key Laboratory of Modeling and Simulation for Complex Systems Beijing100854 China

ISBN: (纸本)9798350303759

Aiming at the problem of periodic interference in flight simulation turntables, a design method of full-form dynamic linearization model free adaptive control (FFDL-MFAC) is proposed. An equivalent dynamic linearized data model is established at each dynamic operating point of the closed-loop system to achieve adaptive control of the nonlinear system, which gives the controller the advantage of online adjustment of internal parameters and improves the robustness of the control system. Aiming at the difficulty of parameter adjustment caused by the increase of dimension of the pseudo partial derivative matrix, a PID-like MFAC parameter adjustment method is proposed, which greatly reduces the difficulty of parameter adjustment of the model-free adaptive controller. The simulation results of MFAC and PID show that the designed FFDL-MFAC controller outperforms the conventional PID in tracking command signals and suppressing periodic disturbances. © 2023 IEEE.

关键词： controllers

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A credibility allocation approach of complex simulation systems 35

A credibility allocation approach of complex simulation syst...

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35th European modeling and Simulation Symposium, EMSS 2023

作者： Zhang, Huan Li, Wei Geng, HuaPin Ma, Ping Yang, Ming Control and Simulation Center Harbin Institute of Technology Harbin150080 China National Key Laboratory of Modeling and Simulation for Complex Systems Harbin150080 China Science and Technology on Complex System Control and Intelligent Agent Cooperation Laboratory Beijing100074 China

ISBN: (纸本)9788885741881

complex simulation systems usually need to satisfy the credibility requirements and the credibility of complex simulation systems is inextricably linked to the credibility of simulation sub-systems. Hence, in order to guarantee the credibility of complex simulation systems meets requirements, it is necessary to allocate the credibility of simulation sub-systems. complex simulation systems are composed of several correlative simulation sub-systems and their credibility has correlation relationships, which makes it difficult to obtain the credibility of simulation sub-systems quickly. The existing works mostly ignore the relationships between the sub-systems and are difficult to generate the credibility allocation results of simulation sub-systems. In this paper, we model the credibility allocation problem as a probabilistic inference problem based on the pairwise Markov random field (PMRF). In addition, we apply several inference algorithms to perform the inference exactly and approximately in the credibility PMRF. Finally, experiments are conduted on the air defense combat complex simulation system, and the experiment results demonstrate that the proposed method can obtain the credibility allocation results quickly and accurately. © 2023 The Authors.

关键词： Inference engines

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A Novel Heterogeneous Actor-critic Algorithm with Recent Emphasizing Replay Memory

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International Journal of Automation and computing 2021年第4期18卷 619-631页

作者： Bao Xi Rui Wang Ying-Hao Cai Tao Lu Shuo Wang State Key Laboratory of Management and Control for Complex Systems Institute of AutomationChinese Academy of SciencesBeijing 100190China University of Chinese Academy of Sciences Beijing 100049China Center for Excellence in Brain Science and Intelligence Technology Chinese Academy of SciencesShanghai 200031China

Reinforcement learning(RL) algorithms have been demonstrated to solve a variety of continuous control tasks. However,the training efficiency and performance of such methods limit further applications. In this paper, we propose an off-policy heterogeneous actor-critic(HAC) algorithm, which contains soft Q-function and ordinary Q-function. The soft Q-function encourages the exploration of a Gaussian policy, and the ordinary Q-function optimizes the mean of the Gaussian policy to improve the training efficiency. Experience replay memory is another vital component of off-policy RL methods. We propose a new sampling technique that emphasizes recently experienced transitions to boost the policy training. Besides, we integrate HAC with hindsight experience replay(HER) to deal with sparse reward tasks, which are common in the robotic manipulation domain. Finally, we evaluate our methods on a series of continuous control benchmark tasks and robotic manipulation tasks. The experimental results show that our method outperforms prior state-of-the-art methods in terms of training efficiency and performance, which validates the effectiveness of our method.

关键词： Reinforcement learning(RL) actor-critic experience replay training efficiency manipulation skill learning

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Robust stability of switched linear systems with polytopic uncertainty

Robust stability of switched linear systems with polytopic u...

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2007 IEEE 22nd International Symposium on Intelligent control, ISIC 2007

作者： Li, Z.G. Wen, C.Y. Soh, Y.C. Media Division Institute for Infocomm Research 21 Heng Mui Keng Terrace Singapore 119613 Singapore Center for Modeling and Control of Complex Systems Nanyang Technological University Nanyang Drive Singapore 639798 Singapore

ISBN: (纸本)142440441X

In this paper, we study robust stability of a class of switched linear systems (SLSs) that is composed of a finite number of linear continuous variable systems (CVSs) and the switchings of CVSs are predefined and represented by a finite state machine. Each CVS consists of a cluster of unstable matrices, which are simultaneously block-triangularizable. This type of SLSs cannot be addressed by existing results. A decomposition method is used to decompose the original system into several lower dimensional SLSs at the diagonal block positions. Our results show that the original higher dimensional SLS is asymptotically stable if all these lower dimensional SLSs are asymptotically stable. The synergy between the continuous of each lower dimensional SLSs and the discrete dynamics is fully utilized by the cycle analysis method to derive sufficient conditions on the robust stability of each lower dimensional SLS. With our method, all CVSs in a cycle instead of each individual CVS is taken as an analysis unit. The condition on the stability of SLSs can then be relaxed in the sense that Lyapunov functions are only required to be non-increasing along each type of cycle instead of each CVS. ©2007 IEEE.

关键词： Linear systems

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Dynamic Walking and Stepping over Large Obstacles of Biped Robots: A Poincaré Map Approach

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Journal of Engineering Science and Technology Review 2022年第6期15卷 186-200页

作者： Kalamain, Nasrin Farrokhi, Mohammad School of Electrical Engineering Iran University of Science and Technology Tehran Iran School of Electrical Engineering Center of Excellence for Modeling and Control of Complex Systems Iran University of Science and Technology Tehran Iran

This paper considers dynamic stepping of biped robots when walking through a big obstacle, which is a great problem for these kinds of robots, using nonlinear model predictive control technique. No need for trajectory planning is one of the key advantages of this method. Hence, the gait length is not predefined and the controller determines it on the basis of the physical restraints and dynamic constancy conditions for approaching the obstacle and stepping over it. The stability and good performance for stepping over large obstacles are guaranteed by the definition of appropriate linear and nonlinear constraints and cost functions. Furthermore, to solve the uncertainty problem corresponding to the biped dynamic model, neural networks are used to identify the model of robot. For stability analysis, the Poincaré map with the fixed-point technique is utilized to guarantee the robot stability. Simulation outcomes indicate excellent efficiency of the suggested technique used to a five-link biped robot crossing over a 40×15 cm obstacle in sagittal plane when preserving a safety clearance from it with no need to a predefined trajectory © 2022 School of Science, IHU. All Rights Reserved.

关键词： Cost functions

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A second-order controller for resonance damping and tracking control of nanopositioning systems 19

A second-order controller for resonance damping and tracking...

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19th International Conference on Adaptive Structures and Technologies 2008, ICAST 2008

作者： Aphale, Sumeet S. Fleming, Andrew J. Moheimani, S.O.R. University of Aberdeen Kings College United Kingdom ARC Center of Excellence for Complex Dynamic Systems and Control University of Newcastle Callaghan Australia School of Electrical Engineering and Computer Science University of Newcastle CallaghanNSW Australia

ISBN: (纸本)9781617389870

This paper presents a simple second-order controller that damps the resonance typical of piezoelectric nanopositioners and delivers good tracking performance. This method employs the Integral Resonant control scheme (IRC) for damping the dominant resonant mode of the piezoelectric nanopositioner and uses an integral controller to achieve tracking performance. As disturbance rejection is a main concern in nanopositioning applications, the control scheme is tested for its disturbance rejection performance. It is seen that the control scheme has good disturbance rejection characteristics deeming it suitable for nanopositioning applications. To test the tracking performance, the system is made to track a 20 Hz triangular input at various integral gains. It is shown that improved tracking performance can be achieved at high gains with only a slight degradation in disturbance rejection performance at high frequencies.

关键词： Disturbance rejection

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Learning regional attention convolutional neural network for motion intention recognition based on EEG data 29

Learning regional attention convolutional neural network for...

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29th International Joint Conference on Artificial Intelligence, IJCAI 2020

作者： Fang, Zhijie Wang, Weiqun Ren, Shixin Wang, Jiaxing Shi, Weiguo Liang, Xu Fan, Chen-Chen Hou, Zengguang State Key Laboratory for Management and Control of Complex Systems Institute of Automation Chinese Academy of Sciences Beijing China University of Chinese Academy of Sciences Beijing China Center for Excellence in Brain Science and Intelligence Technology Beijing China

ISBN: (纸本)9780999241165

Recent deep learning-based Brain-Computer Interface (BCI) decoding algorithms mainly focus on spatial-temporal features, while failing to explicitly explore spectral information which is one of the most important cues for BCI. In this paper, we propose a novel regional attention convolutional neural network (RACNN) to take full advantage of spectral-spatial-temporal features for EEG motion intention recognition. Time-frequency based analysis is adopted to reveal spectral-temporal features in terms of neural oscillations of primary sensorimotor. The basic idea of RACNN is to identify the activated area of the primary sensorimotor adaptively. The RACNN aggregates a varied number of spectral-temporal features produced by a backbone convolutional neural network into a compact fixed-length representation. Inspired by the neuroscience findings that functional asymmetry of the cerebral hemisphere, we propose a region biased loss to encourage high attention weights for the most critical regions. Extensive evaluations on two benchmark datasets and real-world BCI dataset show that our approach significantly outperforms previous methods. © 2020 Inst. Sci. inf., Univ. Defence in Belgrade. All rights reserved.

关键词： Brain computer interface

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Development of a propeller with undulating fins and its characteristics

Development of a propeller with undulating fins and its char...

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2019 IEEE International Conference on Real-Time Computing and Robotics, RCAR 2019

作者： Ma, Ruichen Wang, Yu Wang, Rui Wang, Shuo State Key Laboratory of Management and Control for Complex Systems Institute of Automation Chinese Academy of Sciences Beijing100190 China University of Chinese Academy of Sciences Beijing100049 China CAS Center for Excellence in Brain Science and Intelligence Technology

ISBN: (纸本)9781728137261

This paper addresses some experiments about measurements of thrust and heave force generated by a modular designed biomimetic underwater propeller. The propeller has a ribbon fin that consists of twelve rays linked by a latex membrane. Different forms of waves can be generated by the propeller. A measurement platform is constructed to obtain the thrust and heave force generated by the waves along with the input power of the propeller. Three types of waves are performed on the platform, including sinusoidal waves, fusiform sinusoidal waves and inward counter-propagating sinusoidal waves. By changing the parameters of undulating waves, a total of three hundred series of experiments are implemented. The measurement results of three types of waves are analyzed and the differences among three types of waves are compared. © 2019 IEEE.

关键词： Fins (heat exchange)

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Personalized gait trajectory generation based on anthropometric features using Random Forest

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Journal of Ambient Intelligence and Humanized Computing 2023年第12期14卷 15597-15608页

作者： Ren, Shixin Wang, Weiqun Hou, Zeng-Guang Chen, Badong Liang, Xu Wang, Jiaxing Peng, Liang The State Key Laboratory of Management and Control for Complex Systems Institute of Automation Chinese Academy of Sciences Beijing100190 China University of Chinese Academy of Sciences Beijing100049 China The CAS Center for Excellence in Brain Science and Intelligence Technology Beijing100190 China Institute of Artificial Intelligence and Robotics Xi’an Jiaotong University Xi’an710049 China

Using lower limb rehabilitation robots (LLRRs) to help stroke patients recover their walking ability is attracting more and more attention presently. Previous studies have shown that gait rehabilitation training with natural gait pattern can improve the therapeutic outputs. However, how to generate the personalized gait trajectory has not been well researched. In this paper, a personalized gait generation method based anthropometric features is proposed. Firstly, gait trajectories are fitted and simplified into Fourier coefficient vectors, which are used to represent gait trajectories. Secondly, fourteen body features are used to generate the personalized gait trajectories and the feature set is further optimized based on the minimal redundancy maximal relevance criterion for easy application on the LLRR. Then, the relationship between the optimized feature set and gait trajectories is modeled by using the RF algorithm. Finally, the performance of the proposed method is demonstrated by several comparison experiments. © 2019, Springer-Verlag GmbH Germany, part of Springer Nature.

关键词： Trajectories

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