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Investigation on adaptive pulse width modulation control for high speed on/off valve
Qiang Gao,Yuchuan Zhu,Zhang Luo,Niyomwungeri Bruno 대한기계학회 2020 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.34 No.4
High speed on/off valves (HSV) have often been used to control flow or pressure in digital hydraulic systems due to higher switching frequency. However, the dynamic performance and energy efficiency are highly affected by the supply pressure and the carrier frequency. In this paper, a new adaptive PWM control method for HSV based on software is proposed. The proposed adaptive PWM consists of a reference PWM, an excitation PWM, a high frequency PWM, and a reverse PWM. First, the nonlinear model of the HSV was established, and the structural composition and working principle of the proposed adaptive PWM control strategy were presented. Secondly, individual feedback controllers for the excitation PWM, the high frequency PWM, and the reverse PWM were designed, respectively;and each of the individual feedback controllers was experimentally verified. Finally, the comparative experimental results demonstrated that, with the proposed adaptive PWM control, the rising delay time of the control pressure drastically reduces by 84.6 % (from 13 ms to 2 ms), the duty cycle’s effective range remains large (12 %-85 %) even with high carrier frequency (100 Hz), and the temperature rise of the valve’s coil shell is reduced by 61.5 %, compared to the three-voltage control. In addition, the dynamic performance and the energy efficiency of the HSV are not affected by the supply pressures and carrier frequencies, which proves that the proposed control strategy can improve the robustness and stability of the valve system.
A Novel Single-Mode Lamb Wave Generation Method for Crack Localization of Beam Structures
Qiang Gao,Jun Young Jeon,Yeseul Kong,Gyuhae Park 한국비파괴검사학회 2021 한국비파괴검사학회지 Vol.41 No.2
Structure health monitoring of beam structures is important in civil and mechanical engineering. Lamb waves have the advantages of long propagation distance and low power loss, which are widely used in the field of nondestructive testing. However, Lamb waves generated via conventional methods usually contain multiple modes, and in many cases, the multi-mode Lamb waves cause difficulties in damage detection and localization. This research proposes a novel single-A0 mode Lamb wave generation technique; the actuator is attached on the side surface of a beam structure, and the sensor is attached on the top or bottom surface, which is perpendicular to the side surface, such that the single-A0 mode of the Lamb wave can be generated. Due to the mode conversion effect of the Lamb wave when it passes through a crack, the existence of the crack can be determined by evaluating the existence of the S0 mode. In addition, the crack can be localized accurately using the proposed algorithm. Numerical and experimental investigations are performed to verify the performance of the proposed method. Comparisons with other single-mode Lamb wave generation methods are also performed to validate the advantages of the proposed method.
Tracking Control for a Quadrotor via Dynamic Surface Control and Adaptive Dynamic Programming
Qiang Gao,Xin-Tong Wei,Da-Hua Li,Yue-Hui Ji,Chao Jia 제어·로봇·시스템학회 2022 International Journal of Control, Automation, and Vol.20 No.1
In this paper, a data-driven control algorithm based on the Dynamic Surface Control and the ActionDependent Heuristic Dynamic Programming is proposed to realize the stable tracking control of the quadrotor. Firstly, the dynamic surface control is addressed for the nonlinear model of the quadrotor, which can overcome the “explosion of complexity” problem encountered in traditional back-stepping method inevitably. The controller designed by Dynamic Surface Control is served as the main controller in the total control structure. Secondly, the Action-Dependent Heuristic Dynamic Programming is investigated to construct a complementary attitude controller by involving the learning mechanism. The adoption of Action-Dependent Heuristic Dynamic Programming can provide the capability of adaptation and disturbance rejection to improve the tracking control performance effectively. The overall closed-loop system is proved to be asymptotically stable by the Lyapunov theorem. Finally, the numerical simulation and flight experiments are presented to demonstrate that the proposed tracking control scheme exhibits an excellent tracking performance in the case of external disturbances.
A novel active disturbance rejection-based control strategy for a gun control system
Qiang Gao,Zhan Sun,Guolai Yang,Runmin Hou,Li Wang,Yuan-Long Hou 대한기계학회 2012 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.26 No.12
To compensate for the nonlinearity and to achieve finely-tuned tracking accuracy of a gun control system driven by an AC machine,an improved active disturbance rejection control (IADRC) strategy with neural network embedding (NN-IADRC) is developed in this paper. The proposed IADRC, which has amnestic memory effects, can be regarded as an extension of the conventional ADRC (CADRC),making it a special case of the IADRC. To further attenuate the dependence on system models and enhance the disturbance rejection capacities of the IADRC strategy, an on-line NN-based optimum updating approach is also developed in this paper. Finally, a series of experiments are conducted on the semi-physical simulation platform to estimate the performance of the control system and the effects of the memory factor on the system. The experimental results confirm that the proposed NN-IADRC is highly robust. The results also confirm that it performs more excellently than the CADRC and that its fine tuning has attained tracking accuracy.
Lightweight high-precision pedestrian tracking algorithm in complex occlusion scenarios
Qiang Gao,Zhicheng He,Xu Jia,Yinghong Xie,Xiaowei Han 한국인터넷정보학회 2023 KSII Transactions on Internet and Information Syst Vol.17 No.3
Aiming at the serious occlusion and slow tracking speed in pedestrian target tracking and recognition in complex scenes, a target tracking method based on improved YOLO v5 combined with Deep SORT is proposed. By merging the attention mechanism ECA-Net with the Neck part of the YOLO v5 network, using the CIoU loss function and the method of CIoU non-maximum value suppression, connecting the Deep SORT model using Shuffle Net V2 as the appearance feature extraction network to achieve lightweight and fast speed tracking and the purpose of improving tracking under occlusion. A large number of experiments show that the improved YOLO v5 increases the average precision by 1.3% compared with other algorithms. The improved tracking model, MOTA reaches 54.3% on the MOT17 pedestrian tracking data, and the tracking accuracy is 3.7% higher than the related algorithms and The model presented in this paper improves the FPS by nearly 5 on the fps indicator.
Rapid flow measurement for high speed on/off valve based on coil current derivative
Qiang Gao,Yuchuan Zhu,Yuwen Wang 대한기계학회 2022 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.36 No.6
The average flow rate of a high speed on/off valve (HSV) is usually obtained by a flow sensor, which leads to pressure loss, structural complexity, and long test time. This paper proposes a rapid flow measurement for HSV based on the coil current derivative. The average flow rate is calculated by the effective opening time, which is solved by the critical moving time according to the proposed flow models. To estimate the critical moving time in real-time, an analytical model between the coil current derivative and the valve’s displacement is derived. Experiments indicate that the error between the linear and nonlinear flow model is small when the frequency is smaller than 50 Hz. Moreover, compared to the linear flow model, the average error of the nonlinear flow model decreases from 0.21 L/min to 0.12 L/min under 100 Hz. The proposed flow measurement method has advantages of rapid measurement, structural simplicity, non-contact, and easy to implement intelligence.
An SDN Based CBT for Distributed Shared Memory
Qiang Gao,Weiqin Tong,Samina Kausar,Shengan Zheng 보안공학연구지원센터 2016 International Journal of Grid and Distributed Comp Vol.9 No.1
It is a challenging task to provide an easy–to-use programming interface for distributed shared memory in parallel computing that demands high availability as well as effective synchronization. The current implementations typically use conventional Ethernet as communication medium using broadcast or multicast for synchronization mechanisms. In general, multicast is more efficient than broadcast, as it uses multicast tree to transfer data instead of multicast flooding. Multicast avoids redundant transmissions and lessens network contention. These properties make it significant for distributed shared memory. However, such solution has limited control on response time and process scheduling. This causes uncertainty of time spent in synchronization and interruption of unrelated processes in the same multicast group. In this research, we propose a dynamic SDN multicast mechanism to improve efficiency of synchronization for distributed shared memory by using an SDN-based multicast mechanism and a dynamic core based tree algorithm. The forwarding rule reduces the number of consistency-related messages without interfering the unrelated processes in the same multicast group. The dynamic core-based tree algorithm builds a multicast tree for every multicast group, hereby, SDN controller dynamically adjusts multicast tree according to joining or leaving of nodes. The experiments on the prototype system demonstrate that it could provide better performance compared to the conventional Ethernet based solution in terms of response time and process scheduling in the homogeneous testing environment.