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309 result(s) for "Zhang, Weihai"
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Finite-time adaptive switched gain control for non-strict feedback nonlinear systems via nonlinear command filter
This paper is aimed at developing a finite-time adaptive control for non-strict feedback nonlinear systems with unknown backlash-like hysteresis. First, the adaptive fuzzy systems are applied to identify the unknown functions which contain all the system states. Second, based on the practical finite-time stability criteria, a novel finite-time adaptive switched gain controller via nonlinear command filter is proposed. The stability analysis shows that the tracking error converges to a small region around the origin within a finite time. Meanwhile, all the resulting closed-loop system states are bounded. Finally, simulation examples verify the effectiveness of the designed control scheme.
Research on the Performance of Vehicle Lateral Control Algorithm Based on Vehicle Speed Variation
Analyzing the performance characteristics and applicable environments of intelligent vehicle lateral control algorithms, this paper establishes the Model Predictive Control (MPC), Pure Pursuit (PP), and Linear Quadratic Regulator (LQR) algorithms and uses 2022b MATLAB software to simulate the lateral error, heading error, and algorithm execution time at speeds of 3 m/s, 7 m/s, and 10 m/s. Urban low-speed scenarios (3 m/s) require high-precision control (such as obstacle avoidance), while high-speed scenarios (10 m/s) require strong stability. Existing research mostly focuses on a single speed and lacks a quantitative comparison across multiple operating conditions. Although MPC has high accuracy, its time consumption fluctuates greatly. LQR has strong real-time performance but a wide range of heading errors. PP has poor low-speed performance but controllable high-speed time consumption growth. It is necessary to define the applicable scenarios of each algorithm through quantitative data. In response to the lack of multi-speed domain quantitative comparison in existing research, this paper conducts multi-condition simulations using MPC, PP, and LQR algorithms and finds that at a low speed of 3 m/s, the peak lateral error of PP (0.45 m) is 55% and 156% higher than MPC (0.29 m) and LQR (0.176 m), respectively. At a speed of 10 m/s, the lateral error standard deviation of MPC (0.08 m) is reduced by 68% compared to PP (0.25 m). In terms of algorithm time consumption, LQR maintains full-speed domain stability (0.11–0.44 ms), while PP time increases by 95% with speed from 3 m/s to 10 m/s. The results show that in terms of lateral error, the MPC and LQR algorithms perform more stably, while the PP algorithm has a larger error at low speeds. Regarding heading error, all algorithms have a relatively large error range, but the MPC and LQR algorithms perform slightly better than the PP algorithm at high speeds. In terms of algorithm execution time, the LQR algorithm has the shortest and most stable execution time, the MPC algorithm has a relatively longer execution time, and the PP algorithm’s execution time varies at different speeds. Through this simulation, if high control accuracy and stability are pursued, the MPC or LQR algorithm can be considered; if real-time performance and computational efficiency are more important, the PP algorithm can be considered.
Structural Safety Performance Simulation Analysis of a Certain Electric Vehicle Battery Pack Based on Multi-Working-Condition Safety Evaluation
This study takes the power battery pack of a pure electric vehicle as the research object, focusing on safety—a core concern widely emphasized in the automotive industry. In practical application scenarios, evaluating the safety of the power battery pack through a single operating condition fails to fully reflect its comprehensive safety performance throughout the vehicle’s entire life cycle. To overcome this limitation, a systematic analysis process was established. First, Catia geometric modeling software was used to simplify the battery pack structure, and HyperMesh was then employed for mesh generation. Second, three core analyses were conducted: static analysis, modal analysis, and extrusion condition analysis. A multi-condition safety evaluation system for electric vehicle battery packs during computer simulation analysis was proposed, which evaluates the battery pack from three dimensions: “dynamic stiffness-static strength-extrusion safety”. Results show that: modal analysis reveals the battery pack’s low-order natural frequencies exceed the vehicle’s excitation frequency (excitation point on the case cover); static analysis confirms it meets operational requirements; extrusion verification proves its safety complies with new national standards. The coupling effect of this multi-dimensional analysis breaks through the limitations of safety performance evaluation under a single operating condition, more realistically reflecting the battery pack’s comprehensive safety over its life cycle and providing a more systematic basis for power battery pack optimization.
Event-Triggered Secure Consensus of Stochastic Multi-Agent Systems: A Defense Scheme Against Bilateral False Data Injection Attacks
This paper investigates the event-triggered secure consensus problem for stochastic multi-agent systems (MASs) subject to bilateral false data injection attacks (FDIAs). To achieve reliable secure consensus while reducing resource consumption, an event-triggered defense scheme incorporated with a configurable waiting period is proposed. By introducing an adjustable time interval between consecutive trigger events, the developed scheme not only rigorously eliminates Zeno behavior but also alleviates the computational and sensing burdens. Notably, the analysis of event-triggered secure consensus for stochastic MASs is more challenging compared to conventional deterministic scenarios, due to the coupling effects of stochastic disturbances, event-triggered mechanisms, and bilateral FDIAs. To address this critical challenge, a stochastic convergence theorem is adopted in this study. Distinct from the traditional Lyapunov theorem for stochastic stability analysis, this theorem exhibits inherent similarities to the deterministic Barbalat lemma, which offers a more flexible analytical framework. A key advantage of the proposed approach is that it relaxes the positive definiteness constraint on the candidate Lyapunov function, thereby significantly enhancing the flexibility in constructing Lyapunov functions for stochastic MASs under bilateral FDIAs. Finally, two numerical simulation examples are presented to verify the correctness and effectiveness of the proposed control protocol and key theoretical results.
Research on Path Planning Based on Multi-Dimensional Optimized RRT Algorithm
The Rapidly Exploring Random Tree (RRT) is widely employed in the field of intelligent vehicles, but traditional RRT has issues like inefficient blind expansion, tortuous/discontinuous paths, and slow convergence. Thus, a multi-dimensional optimized RRT is proposed. First, a heuristic search method is adopted to reduce blind sampling, guiding sampling toward the target and cutting irrelevant searches. Second, to fix RRT’s inability to adjust step size dynamically (limiting complex road adaptability), step size is optimized based on environmental information. Third, since treating vehicles as mass points leads to unreasonable paths, sampling points are expanded for practicality. Finally, redundant points are removed via a greedy strategy, and paths are smoothed with quasi-uniform cubic B-splines to meet ride comfort needs. MATLAB R2022b simulations validate the algorithm: in simple scenarios, optimized RRT reduces sampling points to 232 (24.4% of traditional RRT), runtime to 3.25 s (79.4% cut), path length to 673.84 m (15.6% reduction); in complex scenarios, 636 points (37.0%), 11.07 s runtime (58.8% cut), 699.61 m path (21.6% reduction), outperforming traditional RRT and Q-RRT*.
Optimized PAB-RRT Algorithm for Autonomous Vehicle Path Planning in Complex Scenarios
Path planning is a pivotal technology for autonomous vehicles, directly influencing driving safety and comfort. Developing algorithms adaptable to diverse scenarios is critical for ensuring the safe operation of autonomous driving systems and advancing their engineering applications. The existing Rapidly exploring Random Tree (RRT) algorithm has limitations such as low efficiency and tortuous, lengthy paths. To address these issues, this study proposes the PAB-RRT algorithm, which integrates probabilistic goal bias, adaptive step size, and bidirectional exploration into RRT. Comparative simulations were conducted to evaluate PAB-RRT against traditional RRT, RRT*, and single-strategy improved variants (A-RRT, P-RRT, B-RRT). Results show that in static multi-obstacle scenarios, PAB-RRT completes planning with 30 iterations (6.99% of traditional RRT), 0.1255 s computation time (21.9% of traditional RRT), and a 130.83 m path length (7.2% shorter than traditional RRT). In dynamic obstacle scenarios, it requires 19 iterations (0.0434 s) at the initial stage and 37 iterations (0.0861 s) after obstacle movement, with path length stably around 130 m. Overall, PAB-RRT outperforms traditional algorithms in exploration efficiency, path performance, and robustness in complex settings, better meeting the efficiency and reliability requirements of autonomous vehicle path planning under complex scenarios and providing a feasible reference for related technology.
Influence of Multi-Source Electromagnetic Coupling on NVH in Automotive PMSMs
Persistent discrepancies remain in the perceived far-field noise of automotive permanent-magnet synchronous motors (PMSMs) and the predictions of conventional NVH simulations. To bridge this gap, a Tri-source Electromagnetic Coupling NVH Integrated Framework (Tri-ECNVH) is developed, in which air-gap electromagnetic force harmonics, torque ripple, and cogging torque are treated as a coupled excitation system rather than as independent sources. Traditional workflows usually superpose their responses in the power domain, which tends to underestimate the radiating contribution of torque-related excitations and neglect their phase and order coupling with radial electromagnetic forces. In the proposed Tri-ECNVH framework, the three sources are mapped into the order domain, aligned by spatial order, and applied to the stator with phase consistency, so that inter-source coupling and cross terms are explicitly retained along a unified electromagnetic–structural–acoustic chain. Acoustic radiation is evaluated by prescribing the normal velocity on the stator outer surface as a Neumann boundary condition and computing the far-field A-weighted sound pressure level (SPL) using a boundary element method (BEM) model. Numerical results reveal pronounced cooperative amplification of the three sources at critical orders and within perceptually sensitive frequency bands; relative to independent-source modeling with power-domain summation, Tri-ECNVH predicts peak levels that are typically 5–10 dB higher and reproduces the spectral envelope and peak–valley evolution more faithfully. The framework therefore offers a practical, radiation-oriented basis for multi-source noise mitigation in traction PMSMs and helps narrow the gap between simulation and perceived sound quality in automotive applications.
Prediction of Propellant Electrostatic Sensitivity Based on Small-Sample Machine Learning Models
Hydroxyl-terminated-polybutadiene (HTPB)-based composite solid propellants are extensively used in aerospace and defense applications due to their high energy density, thermal stability, and processability. However, the presence of highly sensitive energetic components in their formulations leads to a significant risk of accidental ignition under electrostatic discharge, posing serious safety concerns during storage, transportation, and handling. To address this issue, this study explores the prediction of electrostatic sensitivity in HTPB propellants using machine learning techniques. A dataset comprising 18 experimental formulations was employed to train and evaluate six machine learning models. Among them, the Random Forest (RF) model achieved the highest predictive accuracy (R2 = 0.9681), demonstrating a strong generalization capability through leave-one-out cross-validation. Feature importance analysis using SHAP and Gini index methods revealed that aluminum, catalyst, and ammonium perchlorate were the most influential factors. These findings provide a data-driven approach for accurately predicting electrostatic sensitivity and offer valuable guidance for the rational design and safety optimization of HTPB-based propellant formulations.
Quantum Dots Mediated Crystallization Enhancement in Two-Step Processed Perovskite Solar Cells
Highlights The incorporation of quantum dots (QDs) as crystallization seeds results in the growth of larger perovskite crystals with reduced defect densities and preferential orientations along the (001) and (002) planes, significantly improving the film morphology. The QD-seeded films exhibit reduced non-radiative recombination and enhanced charge transport, as confirmed by steady-state and time-resolved photoluminescence, transient photovoltage measurements, and electrochemical impedance spectroscopy. Devices fabricated with QD-treated films achieve a remarkable power conversion efficiency (PCE) of 24.75% and exhibit exceptional long-term stability under simulated sunlight exposure, retaining 80% of their PCE after 1000 h of continuous illumination. Hybrid organic–inorganic lead halide perovskites have emerged as a promising material for high-efficiency solar cells, yet challenges related to crystallization and defects limit their performance and stability. This study investigates the use of perovskite quantum dots (QDs) as crystallization seeds to enhance the quality of FAPbI 3 perovskite films and improve the performance of perovskite solar cells (PSCs). We demonstrate that CsPbI 3 and CsPbBr 3 QDs effectively guide the crystallization process, leading to the formation of larger crystals with preferential orientations, particularly the (001) and (002) planes, which are associated with reduced defect densities. This seed-mediated growth strategy resulted in PSCs with power conversion efficiencies (PCEs) of 24.75% and 24.11%, respectively, compared to the baseline efficiency of 22.05% for control devices. Furthermore, devices incorporating QD-treated perovskite films exhibited remarkable stability, maintaining over 80% of their initial PCE after 1000 h of simulated sunlight exposure, a significant improvement over the control. Detailed optoelectronic characterization revealed reduced non-radiative recombination and enhanced charge transport in QD-treated devices. These findings highlight the potential of QDs as a powerful tool to improve perovskite crystallization, facet orientation, and overall device performance, offering a promising route to enhance both efficiency and stability in PSCs.