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Dong-Sheng Li,Jiahe Liu,Li Tang,Wei Shen 국제구조공학회 2024 Smart Structures and Systems, An International Jou Vol.33 No.1
Grouting sleeves are an essential connecting component of prefabricated components, and the quality of grouting has a significant influence on structural integrity and seismic performance. The embedded grouting sleeve (EGS)'s grouting defects are highly undetectable and random, and no effective monitoring method exists. This paper proposes an ultrasonic guided wave method and provides a set of guidelines for selecting the optimal frequency and suitable period for the EGS. The optimal frequency was determined by considering the group velocity, wave structure, and wave attenuation of the selected mode. Guided waves are prone to multi-modality, modal conversion, energy leakage, and dispersion in the EGS, which is a multi-layer structure. Therefore, a time-reversal (TR)-based multi-mode focusing and dispersion automatic compensation technology is introduced to eliminate the multi-mode phase difference in the EGS. First, the influence of defects on guided waves is analyzed according to the TR coefficient. Second, two major types of damage indicators, namely, the time domain and the wavelet packet energy, are constructed according to the influence method. The constructed wavelet packet energy indicator is more sensitive to the changes of defecting than the conventional time-domain similarity indicator. Both numerical and experimental results show that the proposed method is feasible and beneficial for the detection and quantitative estimation of the grouting defects of the EGS.
Dong-Dong Mu,Guo-Feng Wang,Yun-Sheng Fan 제어·로봇·시스템학회 2018 International Journal of Control, Automation, and Vol.16 No.4
This paper addresses two interrelated problems concerning the tracking control of podded propulsion unmanned surface vehicle (USV), namely, the modeling of podded propulsion USV, and trajectory tracking controller design. Based on the force analysis, the separation model of podded propulsion USV is established. Furthermore, a practical adaptive neural tracking controller is proposed by backstepping technique, neural network minimum parameter learning method, neural shunting model and auxiliary dynamic system without the exact information of hydrodynamic damping structure and the sea disturbances. Using Lyapunov stability analysis theory, it is proven that all error signals in the system are uniformly ultimately bounded. The advantages of the paper are that first, the underactuated characteristic of podded propulsion USV is demonstrated; then, neural shunting model and neural network minimum parameter learning method are introduced to cope with the problem of "explosion of complexity" and uncertainty factors, respectively; third, auxiliary dynamic system is introduced into controller design to reduce the risk of actuator saturation. Taking into account the above practical problems is helpful to engineering implementation in the marine practice. Finally, numerical simulation has been given to demonstrate the effectiveness of the proposed scheme.
Dong-Dong Mu,Guo-Feng Wang,Yun-Sheng Fan 대한전기학회 2017 Journal of Electrical Engineering & Technology Vol.12 No.6
This paper addresses two interrelated problems concerning the tracking control of pod propulsion unmanned surface vessel (USV), namely, the modeling of pod propulsion USV, and tracking controller design. First, based on MMG modeling theory, the model of pod propulsion USV is derived. Furthermore, a practical adaptive neural tracking controller is proposed by backstepping technique, neural network approximation and adaptive method. Meanwhile, unlike some existing tracking methods for surface vessel whose control algorithms suffer from “explosion of complexity”, a novel neural shunting model is introduced to solve the problem. Using a Lyapunov functional, it is proven that all error signals in the system are uniformly ultimately bounded. The advantages of the paper are that first, the underactuated characteristic of pod propulsion USV is proved; second, the neural shunting model is used to solve the problem of “explosion of complexity”, and this is a combination of knowledge in the field of biology and engineering; third, the developed controller is able to capture the uncertainties without the exact information of hydrodynamic damping structure and the sea disturbances. Numerical examples have been given to illustrate the performance and effectiveness of the proposed scheme.
Dong-Dong Mu,Guo-Feng Wang,Yun-Sheng Fan 제어·로봇·시스템학회 2020 International Journal of Control, Automation, and Vol.18 No.11
This paper addresses the formation tracking control problem of multiple underactuated unmanned surface vehicles. Considering many actual situations, a practical formation control scheme, which is performed by using a leader-follower approach, minimum learning parameter technique, adaptive technology and so on. Firstly, a virtual unmanned surface vehicle is designed according to the location information of the leader unmanned surface vehicle to estimate the leader’s speed information while reducing the communication bandwidth. Secondly, a formationcontrol law is designed to make the follower underactuated unmanned surface vehicles track the leader. Unknown dynamics and external disturbances are regarded as a whole and compensated by the minimum learning parameter technique instead of multi-layer neural network and the neural shunt model can handle multiple derivation problems of virtual control laws. Meanwhile, the robustness of the controlled system is improved through adaptive technology. Besides, an auxiliary design system is employed to constrain the output range of the control law. Finally, numerical simulations are implemented to prove the feasibility of the formation tracking control strategy.