水下无人系统学报

Optimized Smith Predictor Combined with HCOPSO Algorithm for Unman Surface Vehicle Heading Control

LI Zhiqi, LIU Lanjun, CHEN Jialin

, Available online , doi: 10.11993/j.issn.2096-3920.2025-0104

[Abstract](9) [FullText HTML] (5) [PDF 1857KB](3)

Abstract:
In the heading control of high-speed unmanned surface vessel(USV), the presence of time delay elements in both the forward channel and feedback loop significantly degrades the system's overall performance. Moreover, a larger delay to dynamic time ratio further exacerbates the control difficulty. Conventional Smith predictors can only effectively compensate for time delays in the forward channel and are ineffective against time delays in the feedback loop. In this paper, the time delay in the feedback loop is incorporated into the design of the Smith predictor, constructing a predictive model that accounts for time delays in both directions. This approach allows for simultaneous compensation of time delays in both the forward and feedback paths, thereby significantly reducing the erosion of the system's phase margin caused by bidirectional time delays. Furthermore, a hybrid mean center opposition based learning particle swarm optimization (HCOPSO) algorithm is introduced for the parameter tuning of the PID controller. This algorithm employs a mean center opposition - based learning strategy in the early stages of iteration to expand the search range and utilizes an adaptive compression factor in the later stages for fine-tuning. Thus, it combines the advantages of both global exploration and local exploitation. Simulation results based on a USV heading model demonstrate that the improved Smith predictor PID controller shows significant improvements in system overshoot and settling time compared to conventional PID controllers and traditional Smith predictor PID controllers, with a steady-state error of less than 0.1°. When the compensation model of the optimized Smith predictor contains parameter deviations, the system can still maintain good dynamic stability and steady-state accuracy. Additionally, when comparing the HCOPSO algorithm with other algorithms such as PSO, GA, and WOA for parameter optimization of the improved Smith predictor PID controller, the HCOPSO algorithm achieves an ITAE index that is respectively 55.38%, 22.47%, and 24.63% lower than those obtained by PSO, GA, and WOA, and it exhibits stronger disturbance suppression capability and faster heading recovery performance under different disturbance scenarios, which further verifies the effectiveness of the proposed method.

Simulation of PEMFC Voltage Stabilization System for Underwater Unmanned Power Platform Based on Fuzzy Control

BIAN Yangzhen, XIAO Zongliang, YANG Jian, ZHONG Quanming, DING Yi, ZHANG Lin

, Available online , doi: 10.11993/j.issn.2096-3920.2025-0061

[Abstract](12) [FullText HTML] (8) [PDF 2328KB](0)

Abstract:
Aiming at the demand of underwater unmanned power platform for efficient and stable energy system, this paper focuses on the problem of strong nonlinearity and easy fluctuation of the output voltage of proton exchange membrane fuel cell (PEMFC), and proposes a DC-DC converter voltage stabilization strategy based on the fuzzy PID adaptive control.Due to the strong nonlinear characteristics of the output voltage of the PEMFC and its easy to fluctuate, the traditional control methods have limitations in the dynamic response and robustness. limitations of traditional control methods in terms of dynamic response and robustness. In this study, a mathematical model of PEMFC (including Nernst voltage and activation, ohmic, and concentration loss) and a Boost boost circuit model are established to analyze the voltage fluctuation mechanism. The core innovation lies in the design of a fuzzy PID controller with a rule base that deeply couples the PID control principle with the nonlinear characteristics of PEMFC, which realizes the online dynamic self-tuning of proportional, integral, and differential parameters to optimize the DC-DC converter duty cycle in real time. The results show that compared with the traditional PID, the fuzzy PID control can shorten the system regulation time , the steady-state error tends to be close to zero, the output voltage fluctuation range is narrowed to within ±0.5V under the sudden current change condition, and the duty cycle response is more accurate. The fuzzy PID adaptive strategy significantly enhances the dynamic response speed and robustness of the system, providing a reliable theoretical cornerstone and solution for the efficient and stable fluctuation of the energy heart of the underwater unmanned platform.

A Fast Calibration Method for Underwater Camera Intrinsic Parameters Based on Refraction Model

CHEN Junfeng, JIA Guotao, LI Xueyan, LI Yantian, WANG Xian

, Available online , doi: 10.11993/j.issn.2096-3920.2025-0064

[Abstract](22) [FullText HTML] (7) [PDF 2417KB](3)

Abstract:
To address the low operational precision caused by inaccurate camera intrinsic parameters in underwater visual tasks, a fast calibration method for underwater cameras is proposed. A single image containing two sets of mutually orthogonal parallel lines is used in the proposed method. By solving the vanishing points of these lines on the image plane, an orthogonal relationship related to the equivalent focal length is established. This enables the intrinsic parameters of the camera to be determined. To address the underwater imaging distortion problem, the distortion coefficients are solved using the second-order radial distortion model with the minimum reprojection error as the optimization objective, thereby achieving the distortion calibration of underwater images and improving the accuracy of intrinsic parameter calibration. Furthermore, the accuracy of the method in restoring images is demonstrated by comparing in-air target images with their equivalent air images of underwater targets. Experimental results indicate that the proposed method is simple to operate, significantly reduces environmental requirements during camera calibration, effectively enhances calibration speed while maintaining a certain level of accuracy, and is suitable for calibration tasks of underwater cameras.

Research and Implementation of Aperture Measurement Method for Irregular Broken Hole of Target Plate

ZHANG Jianting, JIANG Xiaopeng, QU Chunliang, ZHANG Xitong, XU Bo

, Available online , doi: 10.11993/j.issn.2096-3920.2025-0051

[Abstract](14) [FullText HTML] (12) [PDF 3877KB](0)

Abstract:
In this paper, the method of flow comparison is used to measure the irregular hole diameter of target plate, which is close to the actual working condition, simple and easy to implement, reliable and low in use cost, and solves the technical problems of irregular hole diameter measurement. Accurate measurement of hole size by taking irregular holes as regular holes has special characterization significance for underwater damage effectiveness evaluation. This method can also meet the needs of similar irregular aperture measurement in different industries.

Maximum efficiency tracking and wide power regulation composite control method for underwater MC-WPT system

LI Hao, QIAN Linjun, LI Shenghong, WANG Feng, LI Zhiqiang

, Available online , doi: 10.11993/j.issn.2096-3920.2025-0065

[Abstract](32) [FullText HTML] (23) [PDF 2368KB](1)

Abstract:
Addressing the requirements of maximum efficiency transmission and varying power output for underwater unmanned vehicle wireless charging systems, a composite control method that can both achieve maximum efficiency tracking and adjust output power is proposed in this paper. Firstly, the influencing factors of transmission power and efficiency in underwater MC-WPT systems are analyzed. Focusing on the seawater medium environment, the issue of eddy current loss in the coupling mechanism needs to be considered. A joint simulation method of magnetic field and circuit is adopted to obtain the equivalent resistance of the coupling mechanism's eddy current, and the optimal load is calculated. Secondly, impedance matching is achieved by cascading Cuk converters at the receiving end to track maximum efficiency, while wide power range adjustment is realized by controlling the phase shift angle of the inverter at the transmitting end. In this composite control method, the efficiency and power control loops do not interfere with each other. Finally, a system simulation model was constructed, and an experimental prototype of the MC-WPT system was built. The correctness of the theoretical analysis and proposed methods in the paper was verified through simulation and experiment. The experimental results showed that after introducing the maximum efficiency tracking method, the optimal efficiency could be achieved under various load conditions. Taking the output of 2 kW and a load of 5 Ω as an example, the efficiency increased from 84.8% to 93.1%. In the experiment, when the input voltage varied, power output ranging from 1 kW to 3 kW was achieved at maximum efficiency by adjusting the phase shift angle. Both simulation and experiment demonstrate that the system can maintain high efficiency operation at all times and adjust the output power in real-time according to demand.

Analysis of Spatiotemporal Characteristics for Underwater Target's Comprehensive Magnetic Field

DONG Xinyu, WANG Honglei, YANG Yixin

, Available online , doi: 10.11993/j.issn.2096-3920.2025-0073

[Abstract](59) [FullText HTML] (28) [PDF 1322KB](4)

Abstract:
The accurate modeling of the radiated magnetic field of underwater targets is of great significance to the development of magnetic detection technology. The target radiation magnetic field mainly consists of magnetic anomaly field and wake magnetic field, while the magnetic sensor usually receives the total magnetic field signal during detection. Current research mainly focuses on the simulation analysis of magnetic anomaly fields and wake magnetic fields respectively, lacking systematic studies on the radiation mechanism, propagation model, spatiotemporal characteristics and attenuation laws after their integration. This makes it difficult to effectively promote the development of underwater target magnetic detection technology. To this end, this paper proposes a method for analyzing the spatiotemporal characteristics of the comprehensive magnetic field of underwater targets. COMSOL and MATLAB software are used to model and study the magnetic anomaly field and wake magnetic field respectively. By integrating the two magnetic field models through vector superposition, the spatiotemporal characteristics and attenuation laws of the target's radiated magnetic field are comprehensively analyzed, which improves the solution efficiency and model accuracy of the comprehensive magnetic field. At the same time, it reveals the specific influence law of the target motion parameters on the comprehensive magnetic field, providing theoretical support for the high-precision modeling of underwater target magnetic detection.

Research on the Extraction and Recognition of Space-Time-Frequency Features for Underwater Moving Targets

LIU Xiaochun, YANG Yunchuan, HU Youfeng, WANG Chenyu, LI Yongsheng

, Available online , doi: 10.11993/j.issn.2096-3920.2025-0067

[Abstract](44) [FullText HTML] (22) [PDF 1231KB](2)

Abstract:
Aiming at the issue of inadequate bearing-angle adaptability in active sonar target recognition, this paper elaborates on the physical mechanism of active sonar target information perception from wave equation theory. Based on generalized multiple signal classification(MUSIC) spatial spectrum estimation, a novel method is proposed for acquiring the pseudo three-dimensional spatial feature of underwater targets by incorporating distance information, thereby effectively enhancing the adaptability of spatial features across different bearing angles. Additionally, research is conducted on methods to enhance Pseudo Wigner-Ville Distribution(PWVD) time-frequency features and extract Doppler frequency shift distribution features of moving targets. By leveraging the complementary advantages of these two algorithms, the bearing-angle adaptability is further improved. To address the challenge of scarce and imbalanced underwater target samples, the concept of meta-learning is integrated to construct a data-level fusion target recognition network that incorporates spatial, time-frequency, and Doppler domain features. The network is trained and tested using simulation and experimental data. The results demonstrate that the fusion features significantly improve the bearing-angle adaptability and anti-interference capability, providing a novel approach for the development of intelligent underwater target recognition technology.

Analysis of the Impact of Shock Waves on the Safe Exit of the Rocket-assisted Vehicle Nose Cap during the Thermal Emission Process of a Concentric Canister Launcher

LIU Gangqi, YUAN Xin, GAO Shan, CUI Canli, HUANG Yuxuan

, Available online , doi: 10.11993/j.issn.2096-3920.2024-0156

[Abstract](72) [FullText HTML] (39) [PDF 1755KB](7)

Abstract:
In response to the impact of shock waves on the safety of the rocket-assisted vehicle nose cap during the concentric tube thermal launch process, computational fluid dynamics (CFD) software was used to numerically simulate the ignition and launch process. The propagation process of shock waves and gas generated by solid rocket motors in the concentric tube was analyzed in detail, and the force variation curve of the nose cap under the action of shock waves was obtained, revealing the force mechanism of the nose cap inside the tube under the action of shock waves. The test data of the shock wave opening process during the field test of a certain product further illustrates the force variation process of the nose cap in the shock wave environment. The research results contribute to a clear understanding of the mechanism of force changes on the nose cap under the shock wave during the thermal emission process of concentric cylinders, and can be used to guide the safety design of the nose cap exiting the cylinder.

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