Actuators

19 pages, 3421 KB

Open AccessArticle

Adaptive Parameter Avoidance Control and Safety-Corrected Tracking Framework for Multi-Agent Differential Drive Vehicles

by Wenxue Zhang, Bingkun Shi, Dušan M. Stipanović and Ning Zong

Actuators 2026, 15(4), 229; https://doi.org/10.3390/act15040229 - 20 Apr 2026

Viewed by 251

Abstract

This paper presents a closed-form tracking and collision avoidance framework for multi-agent differential drive robots. Existing reactive methods often rely on purely geometric proximity, leading to conservative detours and local minima. A state-dependent adaptive avoidance strategy is developed to dynamically modulate repulsive forces [...] Read more.

This paper presents a closed-form tracking and collision avoidance framework for multi-agent differential drive robots. Existing reactive methods often rely on purely geometric proximity, leading to conservative detours and local minima. A state-dependent adaptive avoidance strategy is developed to dynamically modulate repulsive forces using the time-derivative of fractional barrier risk functions, alleviating unnecessary evasive maneuvers. Within a convergence vector field (CVF) architecture, an active safety-corrected tracking mechanism orthogonally strips hazardous velocity projections from the spatial error. This mitigates the inherent conflict between target tracking and obstacle repulsion. A matrix projection-based Lyapunov approach demonstrates the finite-time convergence of the vehicle orientation, bounded tracking errors, and collision-free properties of the closed-loop system, with effectiveness further validated through simulations. Full article

(This article belongs to the Special Issue Next-Generation Electric Machine Design and Control for Sustainable Mobility)

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21 pages, 3240 KB

Open AccessArticle

Prediction and Optimization of Assembly Accuracy for Multistage Rotors in Aeroengines

by Fajin Mao, Lin Yue and Wenke Dai

Actuators 2026, 15(4), 228; https://doi.org/10.3390/act15040228 - 19 Apr 2026

Viewed by 320

Abstract

Accurate prediction and optimization of assembly accuracy are critical to ensuring assembly quality and efficiency for multistage connected aero-engine rotors. To mitigate the effects of residual alignment errors induced by repeated component measurements and to avoid the formation of bowed rotors caused by [...] Read more.

Accurate prediction and optimization of assembly accuracy are critical to ensuring assembly quality and efficiency for multistage connected aero-engine rotors. To mitigate the effects of residual alignment errors induced by repeated component measurements and to avoid the formation of bowed rotors caused by conventional stacking strategies that only minimize parallel misalignment, a harmonic decomposition-based registration method is proposed to unify inconsistent measurement datums among multiple setups. Meanwhile, key assembly process parameters are considered simultaneously, including front-and-rear support concentricity, front-and-rear bearing mounting face end-face runout, rotor blade-tip runout, and rotor unbalance. Taking the discrete assembly phase angles of each rotor stage as independent variables, a multi-objective genetic algorithm is adopted to realize the assembly accuracy prediction and optimization of multistage flange-bolted rotors. The proposed method is validated using a four-stage simulated rotor assembly. Experimental results show that the harmonic decomposition-based registration method improves the average geometric prediction accuracy of rotor assembly by 1.2 percentage points, with the prediction error of geometric assembly parameters for each stage not exceeding 8.4% and the unbalance prediction error not exceeding 29.0%. Compared with random assembly, four-objective comprehensive optimization achieves significant reductions in all objectives: front-and-rear support concentricity is reduced by 66.2%, front-and-rear support shoulder end-face runout by 63.9%, blade-tip runout by 16.7%, and unbalance by 33.8%. The residual alignment error compensation method and stacking optimization strategy proposed in this study provide valuable engineering guidance for improving rotor assembly prediction accuracy and enhancing assembly reliability. Full article

(This article belongs to the Section Actuators for Manufacturing Systems)

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16 pages, 10245 KB

Open AccessArticle

A Modular Soft Robot for Pipeline Crawling Based on Thin-Film Actuators

by Xilai Jin, Zhiwei Ji, Anqi Guo, Siqi Yu and Guoqing Jin

Actuators 2026, 15(4), 227; https://doi.org/10.3390/act15040227 - 18 Apr 2026

Viewed by 295

Abstract

Building upon previously developed thin-film modular soft actuators for elongation and deflection, this study develops a modular soft robot for pipeline locomotion, addressing insufficient anchoring capability in confined environments. Conventional inflatable airbags typically expand into spindle-shaped geometries, resulting in limited contact length and [...] Read more.

Building upon previously developed thin-film modular soft actuators for elongation and deflection, this study develops a modular soft robot for pipeline locomotion, addressing insufficient anchoring capability in confined environments. Conventional inflatable airbags typically expand into spindle-shaped geometries, resulting in limited contact length and reduced effective gripping stability. To overcome this issue, a corrugated thin-film gripping actuator is proposed, in which two high-aspect-ratio sub-airbags are arranged above a compression structure to regulate deformation through geometric constraints. Numerical simulation and experimental evaluation were conducted to investigate contact behavior and locomotion performance. Under an input pressure of 30 kPa, the proposed design achieves a contact length of 46 mm, compared to 37 mm for a conventional three-layer airbag configuration under the same conditions, corresponding to a 24.33% increase in a 10 mm plate-spacing environment. The gripping module is integrated into the modular framework to extend the motion primitives of the soft robot to include anchoring functionality. The results indicate that the corrugated structure effectively suppresses the spindle effect and improves contact effectiveness under compression. These findings demonstrate that structural regulation of thin-film pneumatic actuators provides a feasible strategy for enhancing anchoring performance and locomotion capability of soft robots in confined pipeline environments. Full article

(This article belongs to the Special Issue Soft Actuators and Robotics—2nd Edition)

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25 pages, 5129 KB

Open AccessArticle

Active Piezoelectric Control of Three-Dimensional Vibration in a Flexible Circular Shaft via a Fuzzy Adaptive PID Algorithm

by Changhuan Huang, Yang Liu, Jiyuan Zhai, Weichao Chi and Xianguang Sun

Actuators 2026, 15(4), 226; https://doi.org/10.3390/act15040226 - 17 Apr 2026

Viewed by 279

Abstract

Flexible circular shafts are critical components for power transmission in engineering systems. However, they are susceptible to complex three-dimensional coupled vibrations under multidirectional excitations, which can compromise operational stability and lead to structural fatigue. To address this issue, this paper presents an active [...] Read more.

Flexible circular shafts are critical components for power transmission in engineering systems. However, they are susceptible to complex three-dimensional coupled vibrations under multidirectional excitations, which can compromise operational stability and lead to structural fatigue. To address this issue, this paper presents an active control method for the three-dimensional vibration of a piezoelectrically driven flexible circular shaft via a fuzzy adaptive PID algorithm. The study begins by establishing a dynamic model of the system based on the Euler–Bernoulli beam theory and Lagrange equation. This model forms the foundation for the design of a fuzzy adaptive PID controller. The accuracy of the developed model is then validated through simulations and experiments. Subsequently, active vibration control (AVC) experiments are carried out to evaluate the vibration attenuation effectiveness of various control strategies (including a conventional PID controller as the benchmark for comparison) under different types of excitations applied at the shaft root. The results demonstrate that the proposed active control method has superior control performance, and exhibits excellent vibration suppression performance, especially under bidirectional excitation at the natural frequency, where the vibration suppression ratios in the two orthogonal directions reach 93.03% and 92.09%, respectively. Full article

(This article belongs to the Special Issue Vibration Control Based on Intelligent Actuators and Sensors)

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20 pages, 3693 KB

Open AccessArticle

LSTM-Based Reduced-Order Modeling of Secondary Loop of Nuclear-Powered Propulsion Actuation System

by Kaiyu Li, Lizhi Jiang, Xinxin Cai, Fengyun Li, Gang Xie, Zhiwei Zheng, Wenlin Wang, Hongxing Lu and Guohua Wu

Actuators 2026, 15(4), 225; https://doi.org/10.3390/act15040225 - 16 Apr 2026

Viewed by 251

Abstract

The dynamic response of the secondary circuit system in nuclear propulsion plants is critical to the power output, safety, and energy efficiency of nuclear-powered ships. High-fidelity thermo-hydraulic simulation models can accurately capture system transients but are computationally expensive and unsuitable for real-time applications. [...] Read more.

The dynamic response of the secondary circuit system in nuclear propulsion plants is critical to the power output, safety, and energy efficiency of nuclear-powered ships. High-fidelity thermo-hydraulic simulation models can accurately capture system transients but are computationally expensive and unsuitable for real-time applications. To address this limitation, this study proposes a reduced-order dynamic parameter prediction method that integrates high-fidelity simulation with deep learning. A multi-operating-condition simulation model of a typical nuclear-powered ship secondary circuit system is developed to generate time-series data covering load ramping and propulsion mode switching. Based on this dataset, a conventional recurrent neural network (RNN) and a multilayer long short-term memory (LSTM) network are constructed for multivariate autoregressive prediction of 17 key dynamic parameters, and their performances are systematically compared. Results show that the LSTM significantly outperforms the RNN in capturing long-term temporal dependencies, achieving average RMSE and MAPE values of 0.0228% and 0.365%, respectively. The proposed model completes 50-step-ahead prediction within 0.84 s, satisfying real-time requirements. The hybrid simulation-driven and data-driven framework provides a practical solution for intelligent monitoring and control optimization of nuclear-powered ship propulsion systems. Full article

(This article belongs to the Special Issue Active Disturbance Rejection Control: Theory, Design, and Applications in Advanced Actuation Systems)

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26 pages, 8239 KB

Open AccessArticle

A DACO-XGBoost-Driven Method for Evaluating Braking Performance of High-Speed Elevators

by Yefeng Jiang, Dongxin Li, Wanbin Su, Cancan Yi, Ke Li, Wei Shen and Shulong Xu

Actuators 2026, 15(4), 224; https://doi.org/10.3390/act15040224 - 16 Apr 2026

Viewed by 238

Abstract

To address the high labor intensity of weight handling and the low accuracy of testing outcomes in the 125% rated-load down-running braking test for high-speed elevators, this study proposes a numerical-model-driven evaluation method for elevator braking capability based on Dynamic Ant Colony Optimization–eXtreme [...] Read more.

To address the high labor intensity of weight handling and the low accuracy of testing outcomes in the 125% rated-load down-running braking test for high-speed elevators, this study proposes a numerical-model-driven evaluation method for elevator braking capability based on Dynamic Ant Colony Optimization–eXtreme Gradient Boosting (DACO-XGBoost). Firstly, to overcome the limited prediction accuracy caused by insufficient measured samples during braking analysis, vibration and noise effects are both considered, and thus an equivalent dynamic analysis is conducted for no-load up-running and 125% load down-running conditions. Based on this, a simulation-data generation approach was developed to produce loaded down-running braking samples from the no-load up-running operating condition. Secondly, by combining the simulated samples generated by the above model with a limited set of measured samples, an XGBoost model optimized by a dynamic ant colony algorithm was constructed, improving the model’s ability to fit the complex nonlinear relationships in the elevator braking process. This mitigates the constraints imposed by sample scarcity and enables accurate prediction of key braking-performance parameters. Experimental results demonstrate that the proposed DACO-XGBoost substantially improves prediction accuracy. For braking distance, it decreased from 7.5453 to 0.5661 (RMSE) and from 2.7452 to 0.0370 (MAE). For slip amount, it decreased from 60.0307 to 1.2200 (RMSE) and from 7.7401 to 0.8146 (MAE), respectively. Furthermore, after comparisons with RF, GA-RF, and PSO-RF, the effectiveness of the proposed method for quantitative evaluation of braking performance in high-speed elevators was verified. Full article

(This article belongs to the Special Issue Advanced Perception and Control of Intelligent Equipment)

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27 pages, 8918 KB

Open AccessArticle

Fault Diagnosis of Portal Crane Gearboxes Based on Improved CWGAN-GP and Multi-Task Learning

by Yongsheng Yang, Zuohuang Liao and Heng Wang

Actuators 2026, 15(4), 223; https://doi.org/10.3390/act15040223 - 16 Apr 2026

Viewed by 489

Abstract

With increasing port automation and operational intensity, the gearboxes of gantry cranes widely used in bulk cargo terminals are prone to bearing and gear failures under prolonged heavy loads, intense vibrations, and complex operating conditions. Since fault samples often exhibit imbalanced distributions, this [...] Read more.

With increasing port automation and operational intensity, the gearboxes of gantry cranes widely used in bulk cargo terminals are prone to bearing and gear failures under prolonged heavy loads, intense vibrations, and complex operating conditions. Since fault samples often exhibit imbalanced distributions, this imposes two higher requirements on diagnostic methods—first, the ability to effectively address sample imbalance and, second, the capability to simultaneously identify multiple fault categories. To address these challenges, this paper proposes a joint diagnostic method integrating an improved Conditional Wasserstein Generative Adversarial Network with Gradient Penalty (CWGAN-GP) and Multi-Task Learning (MTL). First, the modified CWGAN-GP performs conditional augmentation for minority fault classes, evaluating synthetic sample authenticity and diversity through multiple metrics. Subsequently, a multi-channel diagnostic network is constructed, in which vibration signals are fed into two parallel sub-networks: time–frequency features are extracted from the Short-Time Fourier Transform (STFT)-based time–frequency representations via a residual-block Convolutional Neural Network (CNN), while temporal features are captured from the raw time-domain signal using a Bidirectional Long Short-Term Memory (Bi-LSTM) with an attention mechanism. An attention fusion layer then integrates these two feature types, enabling joint classification of bearings and gears within a multi-task learning framework. Experimental validation on public gearbox datasets and port gantry crane gearbox datasets demonstrates that this method achieves an average diagnostic accuracy exceeding 97%. The proposed method reduces the impact of class imbalance, thereby improving the accuracy and stability of multi-task fault identification. Full article

(This article belongs to the Special Issue Fault Diagnosis and Prognosis in Actuators)

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21 pages, 2410 KB

Open AccessArticle

A Comprehensive Experimental–Analytical Framework for Motorcycle Testing with Fourier-Based Curve Fitting and Adaptive Control

by Firat Can Yilmaz, Muzaffer Metin and Talha Oguz

Actuators 2026, 15(4), 222; https://doi.org/10.3390/act15040222 - 16 Apr 2026

Viewed by 358

Abstract

Traditional simulators predominantly operate with position control at specific frequencies and largely neglect the appropriate imposition of accelerations on the structure. This restricts the application of realistic accelerations during fatigue testing and reduces the fidelity of tests to real road conditions. This study [...] Read more.

Traditional simulators predominantly operate with position control at specific frequencies and largely neglect the appropriate imposition of accelerations on the structure. This restricts the application of realistic accelerations during fatigue testing and reduces the fidelity of tests to real road conditions. This study proposes an integrated experimental–analytical framework for motorcycle testing under laboratory conditions. Within the framework, smooth displacement reference signals are generated from noisy field-measured acceleration signals through Fourier-based harmonic curve fitting and analytic integration. Subsequently, a nonlinear adaptive backstepping control algorithm is designed to ensure accurate replication of these references within the 0–25 Hz bandwidth under parametric uncertainties. This approach provides a valuable and repeatable alternative to conventional on-road testing, ensuring that realistic road-induced accelerations are accurately imposed on the motorcycle structure during fatigue testing. Experimental signals were collected from a motorcycle on three different road surfaces, and the performance of the generated reference signals was evaluated in both the time and frequency domains. Experiments conducted on a real-time industrial controller demonstrated that the proposed controller exhibits superior tracking performance across all road profiles, achieving a Root Mean Square Error (RMSE) as low as 1.3 mm, while the Fourier-based reconstruction achieves

R^{2}

values approaching 0.97. The controller maintains consistent precision and negligible performance variance despite significant differences in road characteristics, thereby offering a controlled and cost-effective laboratory simulation alternative to conventional on-road durability testing. Full article

(This article belongs to the Special Issue Integrated Intelligent Vehicle Dynamics and Control—2nd Edition)

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17 pages, 8475 KB

Open AccessArticle

Asymptotic Stabilization Control Based on Trajectory Optimization for Vertical Underactuated Manipulators with the First Joint Actuator

by Yufei Chen, Lejun Wang, Bin He, Lei Qin and Yu Gao

Actuators 2026, 15(4), 221; https://doi.org/10.3390/act15040221 - 16 Apr 2026

Viewed by 321

Abstract

Underactuated system control is a central topic in nonlinear system control. For the three-link vertical underactuated manipulator with only the first joint actuated (APP manipulator), the control objective of swing-up and balancing is challenging. The advantages of this paper are as follows: (i) [...] Read more.

Underactuated system control is a central topic in nonlinear system control. For the three-link vertical underactuated manipulator with only the first joint actuated (APP manipulator), the control objective of swing-up and balancing is challenging. The advantages of this paper are as follows: (i) The proposed method avoids balancing region division in common partitioned control, preventing failure to stabilize at the target position due to improper partitioning. (ii) The time-based switching condition optimized via parameter tuning is easier to satisfy than the state-based condition. (iii) The proposed controller effectively suppresses state fluctuations caused by switching, yielding a smoother transition. (iv) The proposed controller avoids the singularity problem. The main procedures are as follows. First, the dynamic model of the APP manipulator is established. Then, a trajectory is designed to guide the active link from the initial position to the vicinity of the target position. On this basis, to ensure that all links can simultaneously reach the vicinity of the target position, the trajectory parameters are optimized according to the coupling relationship between the links. Next, an NFTSM-based tracking controller is developed to steer the links along the optimized trajectory. After that, an LQR-based stabilization controller is further employed to lock the system at the target position. Finally, the effectiveness of the proposed method is verified through simulations. Full article

(This article belongs to the Special Issue Motion Planning, Trajectory Prediction, and Control for Robotics—2nd Edition)

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24 pages, 13036 KB

Open AccessArticle

Zero-Sequence Current Suppression Strategy for a Common DC Bus OW-FPPMSM with Third-Harmonic Current Injection

by Weijie Hao and Yiguang Chen

Actuators 2026, 15(4), 220; https://doi.org/10.3390/act15040220 - 15 Apr 2026

Viewed by 452

Abstract

In the open-winding motor fed by a common DC bus, unbalanced inverter common-mode voltage (CMV), zero-sequence components of the permanent magnet flux linkage, and the PWM dead-time effect can induce a zero-sequence current (ZSC) through the inherent current path. For an open-winding five-phase [...] Read more.

In the open-winding motor fed by a common DC bus, unbalanced inverter common-mode voltage (CMV), zero-sequence components of the permanent magnet flux linkage, and the PWM dead-time effect can induce a zero-sequence current (ZSC) through the inherent current path. For an open-winding five-phase permanent magnet synchronous motor (OW-FPPMSM) applied in an aerospace rocket starter-generator system, two ZSC suppression strategies based on zero-sequence voltage (ZSV) generation mechanisms are proposed in this paper, which improve motor performance in a simple and efficient manner. In the first strategy, the conventional method is modified to enable asynchronous operation of the two inverters, thereby generating the required ZSV pulses. The switching order and time offset between the two inverters are determined by the reference ZSV. The second strategy employs basic voltage vectors with larger magnitudes, resulting in higher DC bus voltage utilization. By adjusting the switching sequence of the second inverter, the ZSC components at the carrier frequency are eliminated. Both strategies also achieve the injection of the third-harmonic current. Finally, the two strategies are further analyzed in terms of the modulation index and ZSV modulation range. Simulation and experimental results verify the effectiveness of the ZSC suppression strategies. Full article

(This article belongs to the Special Issue Advanced Technologies on the Control Method of Electromagnetic Actuator—Second Edition)

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19 pages, 1971 KB

Open AccessArticle

Displacement and Flow Ripple of an Axial Floating Piston Pump

by Bao-Yu Liu, Lan-Kang Li, Gao-Cheng An, Hao-Lin Li and Li-Feng Ma

Actuators 2026, 15(4), 219; https://doi.org/10.3390/act15040219 - 15 Apr 2026

Viewed by 245

Abstract

Axial floating piston pumps (AFPPs) have been proposed as a promising solution to address the increasingly demanding operating conditions of hydraulic pumps, including wide speed ranges, high-pressure environments, and low-viscosity media. To systematically investigate the displacement characteristics and flow pulsation rate of AFPPs, [...] Read more.

Axial floating piston pumps (AFPPs) have been proposed as a promising solution to address the increasingly demanding operating conditions of hydraulic pumps, including wide speed ranges, high-pressure environments, and low-viscosity media. To systematically investigate the displacement characteristics and flow pulsation rate of AFPPs, this study develops a mathematical model via the coordinate transformation method to precisely determine the coordinates of each cylinder. Based on this model, analytical formulas for displacement and flow pulsation rate were derived. Furthermore, the influence trends of diverse geometric parameters on these two metrics were analyzed, accounting for variations in installation methods and structural configurations. Validation was conducted through simulations and experimental tests on an AFPP prototype with specific parameters, confirming the accuracy of the theoretical analysis. This work provides a robust theoretical foundation for the optimal design and performance improvement of AFPPs in practical engineering applications. Full article

(This article belongs to the Section Control Systems)

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4 pages, 151 KB

Open AccessEditorial

Actuator Technologies and Control: Materials, Devices and Applications

by Paolo Mercorelli

Actuators 2026, 15(4), 218; https://doi.org/10.3390/act15040218 - 14 Apr 2026

Viewed by 467

Abstract

Actuation technologies lie at the heart of modern engineering systems, providing the means by which computational intelligence and control decisions are translated into purposeful physical action [...] Full article

(This article belongs to the Special Issue Actuator Technologies and Control: Materials, Devices and Applications)

19 pages, 13360 KB

Open AccessArticle

Research on Coordinated Control Strategy of DHT Mode Switching Based on Multiple Power Sources

by Zhigang Zhang, Hao Yang, Xiaosong Wang, Zhige Chen, Hai Qing and Xiaolin Tang

Actuators 2026, 15(4), 217; https://doi.org/10.3390/act15040217 - 13 Apr 2026

Viewed by 427

Abstract

To suppress the severe output torque fluctuations caused by clutch engagement when a hybrid electric vehicle equipped with a dedicated hybrid transmission (DHT) switches from pure electric (E) drive mode to hybrid (H) drive mode, a coordinated control method for power source switching [...] Read more.

To suppress the severe output torque fluctuations caused by clutch engagement when a hybrid electric vehicle equipped with a dedicated hybrid transmission (DHT) switches from pure electric (E) drive mode to hybrid (H) drive mode, a coordinated control method for power source switching is proposed. First, an adaptive fuzzy proportional-integral (PI) controller regulates the engine speed based on the speed difference between the engine and the P2 motor. Second, an active disturbance rejection control (ADRC) controller is employed for trajectory tracking to eliminate the speed difference across the synchronizer’s friction surfaces. This compensates for clutch torque variations during engine startup and ensures rapid synchronizer engagement. Finally, the torque interruption caused by the decoupling of the engine and P2 motor from the driveline is compensated via feedforward control from the P3 motor. The proposed strategy was validated through MATLAB Simulink simulations and CANape calibration tests. The results indicate that applying the proposed method to E-H mode switching slightly extended the total duration by 0.02 s. However, compared with uncoordinated control, the maximum longitudinal jerk was reduced by 73.8%, and the clutch sliding work decreased by 38.6%. This significantly enhances switching smoothness and prolongs the clutch’s service life. Full article

(This article belongs to the Section Actuators for Surface Vehicles)

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24 pages, 2992 KB

Open AccessArticle

Hybrid Learning-Based Control of Closed-Kinematic Chain Mechanism Robot Manipulators

by Charles C. Nguyen, Tuan M. Nguyen, Ha T. T. Ngo, Tri T. Nguyen and Tu T. C. Duong

Actuators 2026, 15(4), 216; https://doi.org/10.3390/act15040216 - 13 Apr 2026

Viewed by 305

Abstract

This paper presents a novel hybrid learning-based control scheme for position control of robot manipulators whose structure is based on a closed-kinematic-chain mechanism (CKCM). The developed control scheme integrates two complementary control components: the feedback controller and the learning controller. The feedback controller [...] Read more.

This paper presents a novel hybrid learning-based control scheme for position control of robot manipulators whose structure is based on a closed-kinematic-chain mechanism (CKCM). The developed control scheme integrates two complementary control components: the feedback controller and the learning controller. The feedback controller is designed using linearization about a desired trajectory and a PID control law whose gains are selected by a tuning algorithm to guarantee semi-global stability of the linearized closed-loop feedback system. The learning controller incorporates PID-type iterative learning strategy to generate additional control inputs to compensate for modeling uncertainties and unmodeled dynamics. By updating the control input iteratively from trial to trial, the learning controller progressively improves the overall control performance. The effectiveness of the developed control scheme is demonstrated through computer simulations conducted on a six-degree-of-freedom CKCM robot manipulator. Simulation results are presented and discussed to evaluate the tracking accuracy of the developed approach. Full article

(This article belongs to the Section Actuators for Robotics)

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24 pages, 4524 KB

Open AccessArticle

Anti-Disturbance Gimbal Control via Adaptive Proportional-Integral-Resonant Controller and ESO for Control Moment Gyroscope with Vibration Isolator

by Shaobo Li, Zhong Wu and Boxu Zhu

Actuators 2026, 15(4), 215; https://doi.org/10.3390/act15040215 - 13 Apr 2026

Viewed by 413

Abstract

In order to mitigate the effects of micro-vibrations due to control moment gyroscopes (CMGs) on spacecraft attitude control system, they are often mounted on isolation platforms. However, the flexible deformation of isolators may cause certain disturbances in CMG gimbal servo systems. In addition, [...] Read more.

In order to mitigate the effects of micro-vibrations due to control moment gyroscopes (CMGs) on spacecraft attitude control system, they are often mounted on isolation platforms. However, the flexible deformation of isolators may cause certain disturbances in CMG gimbal servo systems. In addition, gimbal servo systems also suffer from intrinsic disturbances due to rotor imbalance and gimbal components. Since these disturbances are distributed over a wide frequency range, they are difficult to suppress and may seriously deteriorate gimbal control performance. To suppress multiple disturbances and improve gimbal speed accuracy, a composite anti-disturbance control method is proposed. The proposed method consists of two components. The first component adopts an adaptive proportional-integral-resonant controller with phase compensation to suppress disturbance due to isolator and rotor imbalance disturbance with improved transient performance. The second component adopts an adaptive extended state observer to estimate and then compensate slowly varying disturbances with improved dynamic performance and steady-state accuracy. By integrating these two components, the proposed method can effectively suppress multiple disturbances in CMG gimbal servo systems. Simulation and experimental results demonstrate the superior performance of the proposed method. Full article

(This article belongs to the Special Issue Advanced Measurement, Drive, and Control of Electric Actuators for Aerospace Vehicles)

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18 pages, 1695 KB

Open AccessArticle

Trajectory Tracking Control of Lower Limb Rehabilitation Exoskeleton Robot Based on Adaptive-Weight MPC

by Linqi Zheng, Yuan Zhou, Anjie Mao and Shuwang Du

Actuators 2026, 15(4), 214; https://doi.org/10.3390/act15040214 - 11 Apr 2026

Viewed by 382

Abstract

In this paper, an adaptive-weight model predictive control (AW-MPC) strategy is proposed to address the trajectory tracking problem of a lower-limb rehabilitation exoskeleton robot. First, based on human motion analysis, the dynamics of the lower-limb rehabilitation exoskeleton are established, and the nonlinear dynamic [...] Read more.

In this paper, an adaptive-weight model predictive control (AW-MPC) strategy is proposed to address the trajectory tracking problem of a lower-limb rehabilitation exoskeleton robot. First, based on human motion analysis, the dynamics of the lower-limb rehabilitation exoskeleton are established, and the nonlinear dynamic model is transformed into a linear model. Second, a MPC objective function is formulated to minimize the tracking error, yielding the optimal control input. Then, on the basis of conventional MPC, a weight-tuning scheme is developed: a weighting function is constructed according to the evolution of the tracking error to adaptively adjust the MPC weighting coefficients, and the closed-loop stability of the control system is proven via a Lyapunov-based analysis. Finally, the proposed method is validated on a lower-limb rehabilitation exoskeleton experimental platform, with a PID controller designed as a baseline for comparison. The experimental results demonstrate that, compared with the PID controller, the proposed AW-MPC achieves faster convergence of the tracking error, higher tracking accuracy, and enhanced robustness. Full article

(This article belongs to the Special Issue Advanced Perception and Control of Intelligent Equipment)

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30 pages, 40596 KB

Open AccessArticle

Three-Vector-Based Model Predictive Direct Speed Control Strategy for Enhanced Target Tracking in Risley Prism Systems

by Hao Lu, Bo Liu, Jianwen Guo, Yuqi Shan, Hao Yi, Yun Jiang, Lan Luo, Feifan He, Taibei Liu, Zixun Wang and Yongqi Yang

Actuators 2026, 15(4), 213; https://doi.org/10.3390/act15040213 - 11 Apr 2026

Viewed by 475

Abstract

When the Risley prism pair is used for target tracking, the nonlinear relationship between beam deflection and prism rotation makes tracking performance highly dependent on precise and stable motor control over a wide speed range. Although the brushless DC motor serves as the [...] Read more.

When the Risley prism pair is used for target tracking, the nonlinear relationship between beam deflection and prism rotation makes tracking performance highly dependent on precise and stable motor control over a wide speed range. Although the brushless DC motor serves as the preferred drive source, its inherent commutation torque ripples directly induce beam pointing jitter, severely degrading overall tracking accuracy and stability. To address these issues, this paper proposes a three-vector-based model predictive direct speed control method. This approach establishes a direct speed-to-torque control channel by generating reference active power through dynamic equations, eliminating the need for fitting a constant flux linkage and parameter tuning. Simultaneously, combined with three-vector optimization and seven-segment modulation strategies, it achieves a dynamic balance between high-frequency, instantaneous electromagnetic power fine-tuning and inherent mechanical inertia of the rotor. Simulation results demonstrate that the proposed method exhibits superior speed stability compared to the conventional double-vector-based model predictive power control method and maintains high-precision dynamic tracking over a wide speed range. Ultimately, it leads to an average reduction of over 60% in the time-weighted absolute tracking error integral under various target trajectories, providing an effective solution for drive control of target tracking in Risley prism systems. Full article

(This article belongs to the Special Issue Intelligent and Precision Control for Mechatronic/Electro-Hydraulic Systems—Second Edition)

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24 pages, 10740 KB

Open AccessArticle

HAML: Humanoid Adversarial Multi-Skill Learning via a Single Policy

by Xing Fang, Honghao Liao, Yanyun Chen, Wenhao Tan and Xiaolei Li

Actuators 2026, 15(4), 212; https://doi.org/10.3390/act15040212 - 11 Apr 2026

Viewed by 426

Abstract

Translating large-scale motion datasets into robust, deployable humanoid controllers is a critical challenge in engineering informatics, primarily due to the scarcity of high-quality annotations, the risk of mode collapse in conditional generation, and the strict constraints of onboard computing hardware. This paper presents [...] Read more.

Translating large-scale motion datasets into robust, deployable humanoid controllers is a critical challenge in engineering informatics, primarily due to the scarcity of high-quality annotations, the risk of mode collapse in conditional generation, and the strict constraints of onboard computing hardware. This paper presents a deployable two-stage learning system that maps clip-level motion datasets to a single-policy multi-skill controller and its deployable counterpart. We adopt coarse one-hot skill labels that can be assigned automatically at the clip level with negligible manual effort, enabling scalable dataset construction. To prevent conditional discriminators from ignoring skill conditions, we inject mismatched (transition, label) pairs and introduce a condition-aware loss that explicitly penalizes incorrect transition–label associations, improving controllability and mitigating mode collapse. For real-world deployment, we further propose a two-stage training strategy: a privileged teacher policy is first trained in simulation and then distilled into a student policy that relies on stacked historical proprioceptive observations, ensuring robustness against sensing noise and latency without relying on external state estimation. Extensive evaluations in simulation and on real hardware demonstrate improved skill coverage, transition coverage, realism, and training efficiency across heterogeneous embodiments. With the onboard computer of a Unitree G1 robot, the distilled policy runs at 100 Hz with 15–25 ms latency, confirming the system’s engineering feasibility. Full article

(This article belongs to the Section Actuators for Robotics)

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21 pages, 8757 KB

Open AccessArticle

A Study on Control System Design for Tugboat-Assisted Vessel Berthing Under Tugboat Failure

by Jung-Suk Park, Young-Bok Kim and Thinh Huynh

Actuators 2026, 15(4), 211; https://doi.org/10.3390/act15040211 - 8 Apr 2026

Viewed by 373

Abstract

This paper investigates the controllability of vessel berthing systems assisted by multiple tugboats under actuator faults or failures. In such interconnected systems, a failure of an individual tugboat can potentially compromise the berthing operation, or even lead to the collapse of the entire [...] Read more.

This paper investigates the controllability of vessel berthing systems assisted by multiple tugboats under actuator faults or failures. In such interconnected systems, a failure of an individual tugboat can potentially compromise the berthing operation, or even lead to the collapse of the entire system. To address this challenge, the dynamic model of the multi-tug-assisted vessel system is first derived, followed by a controllability analysis under various fault scenarios to identify tolerable fault configurations. Then, a robust controller is proposed, integrating an adaptive disturbance observer with finite-time sliding mode control. This design ensures effective rejection of maritime environmental disturbances, practical finite-time stability, and bounded trajectory tracking errors. To accommodate different fault conditions, a switching control allocation strategy is developed to redistribute control efforts among the remaining healthy tugboats, thereby maintaining system reliability and efficiency. Simulation results under various faulty conditions demonstrate the effectiveness and robustness of the proposed control approach. Full article

(This article belongs to the Special Issue Advances in Dynamics and Motion Control of Unmanned Aerial/Underwater/Ground Vehicles—2nd Edition)

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19 pages, 3273 KB

Open AccessArticle

A Comprehensive Analysis of Human–Machine Interaction: Teaching Pendant vs. Gesture Control in Industrial Robotics

by Robert Kristof, Valentin Ciupe, Erwin-Christian Lovasz and Ghadeer Ismael

Actuators 2026, 15(4), 210; https://doi.org/10.3390/act15040210 - 8 Apr 2026

Viewed by 411

Abstract

In collaborative robotics, efficiency and user experience play a central role. This study looks at how perceived performance differs from measured performance when comparing two ways of controlling industrial robots: traditional teaching pendants and wearable EMG-based gesture control. A Myo Armband was used [...] Read more.

In collaborative robotics, efficiency and user experience play a central role. This study looks at how perceived performance differs from measured performance when comparing two ways of controlling industrial robots: traditional teaching pendants and wearable EMG-based gesture control. A Myo Armband was used as an accessible 8-channel EMG platform, and three experiments were carried out on a Universal Robots UR10e to test pick-and-place tasks and precision positioning. Time and accuracy data were gathered together with blind feedback from 13 participants through a multi-criteria analysis framework. Even though the teaching pendant turned out to be more accurate in every scenario, 85% of participants still rated gesture control higher in overall satisfaction. These results point to a notable gap between what users perceive and how they actually perform and suggest that user experience deserves more weight in the design of future robot control interfaces. Full article

(This article belongs to the Special Issue Actuation and Sensing of Intelligent Soft Robots—2nd Edition)

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23 pages, 3301 KB

Open AccessArticle

Hierarchical Active Perception and Stability Control for Multi-Robot Collaborative Search in Unknown Environments

by Zeyu Xu, Kai Xue, Ping Wang and Decheng Kong

Actuators 2026, 15(4), 209; https://doi.org/10.3390/act15040209 - 7 Apr 2026

Viewed by 480

Abstract

Multi-robot systems (MRS) have attracted a lot of attention from researchers due to their widespread application in various environments. However, in multi-robot collaborative search tasks, two problems often arise: sparse rewards for capturing targets and control oscillations. To address these issues, this paper [...] Read more.

Multi-robot systems (MRS) have attracted a lot of attention from researchers due to their widespread application in various environments. However, in multi-robot collaborative search tasks, two problems often arise: sparse rewards for capturing targets and control oscillations. To address these issues, this paper proposes the hierarchical active perception multi-agent deep deterministic policy gradient (HAP-MADDPG) framework. This framework guides robots to efficiently explore maps and discover targets through global utility planning based on global exploration rate and local information aggregation based on local exploration rate. A stability control mechanism, which includes hysteresis logic and reward decay, is introduced to suppress control oscillations. Experimental results show that the HAP-MADDPG framework achieves a success rate of 96.25% and an average search time of 216.3 steps. The path trajectories are smooth, demonstrating the effectiveness of the proposed approach. Full article

(This article belongs to the Special Issue Intelligent Planning and Collaborative Control for Unmanned Swarm Systems)

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20 pages, 4228 KB

Open AccessArticle

Design and Application of an Automated Microinjection System Combining Deep Learning Vision Positioning and Neural Network Sliding Mode Motion Control

by Zhihao Deng, Yifan Xu and Shengzheng Kang

Actuators 2026, 15(4), 208; https://doi.org/10.3390/act15040208 - 5 Apr 2026

Viewed by 359

Abstract

Microinjection is one of the most established and effective techniques for introducing foreign substances into cells. However, issues such as cumbersome procedures, low success rates, and poor repeatability in manual cell microinjection have seriously restricted its practical applications in biomedical research and engineering. [...] Read more.

Microinjection is one of the most established and effective techniques for introducing foreign substances into cells. However, issues such as cumbersome procedures, low success rates, and poor repeatability in manual cell microinjection have seriously restricted its practical applications in biomedical research and engineering. Responding to such problems, this paper designs an automated microinjection system that combines deep learning visual positioning and adaptive neural network sliding-mode motion control. The machine vision solution based on the deep learning YOLOv8 target detection algorithm is utilized by the system to provide positional prerequisites for automated microinjection. Then, stable and fast puncture is completed by controlling the end effector (composed of a piezoelectric actuator and a displacement amplification mechanism). Since the piezoelectric actuator has strong nonlinearity, the motion control of the end effector adopts the control strategy combining sliding mode variable structure and adaptive neural networks to meet the requirements of precise displacement output of microinjection. At the same time, a host computer control system is developed to integrate hardware equipment, visual positioning algorithms and motion control algorithms to achieve corresponding automated microinjection tasks. Finally, the effectiveness of the designed automated microinjection system is successfully verified on zebrafish embryos. Full article

(This article belongs to the Special Issue Intelligent and Precision Control for Mechatronic/Electro-Hydraulic Systems—Second Edition)

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19 pages, 3330 KB

Open AccessArticle

Design and Experiment for a Single-Degree-of-Freedom Four-Bar Planting Manipulator

by Yugong Dang, Gaohang Jiang, Yupeng Zhang and Zhigang Zhou

Actuators 2026, 15(4), 207; https://doi.org/10.3390/act15040207 - 4 Apr 2026

Viewed by 405

Abstract

At present, commonly used vegetable pot seedling planters can be divided into two categories: one has a complex structure and high manufacturing cost, and the other has a simple structure but poor planting quality. In order to solve this problem, an open-hinge four-bar-mechanism [...] Read more.

At present, commonly used vegetable pot seedling planters can be divided into two categories: one has a complex structure and high manufacturing cost, and the other has a simple structure but poor planting quality. In order to solve this problem, an open-hinge four-bar-mechanism planting manipulator is designed, which has many advantages, such as a simple structure, strong force transfer performance, and the ability to achieve complex trajectory curves. The physical characteristics of pot seedlings are measured; this provides a basis for the structural and dimensional design of the planter and the shape design of the duckbill. According to the analysis of the planting process, the design requirements of the planting mechanism are formulated. The motion path of the mechanism and the motion of each pair are planned and designed; a planetary gear train is used to restrain the rotating pair consisting of connecting rod 1 and connecting rod 2; a cam high pair mechanism is used to restrain the rotating pair consisting of connecting rod 2 and connecting rod 3; and a cam linkage mechanism is used to control the opening and closing action of the duckbill. Finally, a single-degree-of-freedom fully mechanical planting mechanism is designed. The experimental results show that the trajectory of the initial soil entry point of the planting mechanism is consistent with the design requirements and theoretical simulation results. In the transplanting experiment, the rate of qualified planting erectness was 94.79%, among which the rate of excellent planting erectness was 92.45%, and the mechanism has high reliability. The design of this mechanism offers a fully automatic pot seedling planting method, which can provide a reference for research on the full automation of transplanting equipment. Full article

(This article belongs to the Special Issue High-Performance Control of Electromechanical Servo System Based on Motor/Hydraulic Actuator)

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20 pages, 6648 KB

Open AccessArticle

Sensorless Collision Detection and Classification in Collaborative Robots Using Stacked GRU Networks

by Jong Hyeok Lee, Minjae Hong and Kyu Min Park

Actuators 2026, 15(4), 206; https://doi.org/10.3390/act15040206 - 4 Apr 2026

Viewed by 450

Abstract

The increasing deployment of collaborative robots in industrial manufacturing environments has enabled close human–robot collaboration, making rapid and reliable collision detection essential for worker safety. This paper presents a learning-based framework for real-time detection and classification of hard and soft collisions using stacked [...] Read more.

The increasing deployment of collaborative robots in industrial manufacturing environments has enabled close human–robot collaboration, making rapid and reliable collision detection essential for worker safety. This paper presents a learning-based framework for real-time detection and classification of hard and soft collisions using stacked Gated Recurrent Unit (GRU) networks. A two-stage pipeline is introduced, in which collision detection and collision type classification are performed sequentially using separate models, and its performance is validated through extensive experiments on a collision dataset collected from a six-joint collaborative robot executing random point-to-point motions. Without requiring joint torque sensors, unmodeled joint friction is implicitly compensated through learning for both detection and classification. Compared to our previous work, the proposed method achieves improved detection performance, and its robustness is further demonstrated through systematic generalization experiments under simulated dynamic model uncertainties. In addition, the classification model accurately distinguishes between hard and soft collisions, providing a basis for differentiated post-collision reaction strategies. Overall, the proposed sensorless collision detection and classification framework provides a practical and cost-effective solution for real-world industrial human–robot collaboration. Full article

(This article belongs to the Special Issue Machine Learning for Actuation and Control in Robotic Joint Systems)

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21 pages, 3106 KB

Open AccessArticle

Trajectory Tracking Control for Lane Change Maneuvers: A Differential Steering Approach for In-Wheel Motor-Driven Electric Vehicles

by Rizwan Ali, Haiting Ma, Jiaxin Mao and Jie Tian

Actuators 2026, 15(4), 205; https://doi.org/10.3390/act15040205 - 4 Apr 2026

Viewed by 380

Abstract

To ensure reliable lane change behavior in-wheel motor-driven electric vehicles (IWM-EVs) under steer-by-wire (SBW) failure, this paper presents an integrated lateral–longitudinal lane change control strategy based on differential steering. The control framework and relevant models are first established. An upper-layer model predictive control [...] Read more.

To ensure reliable lane change behavior in-wheel motor-driven electric vehicles (IWM-EVs) under steer-by-wire (SBW) failure, this paper presents an integrated lateral–longitudinal lane change control strategy based on differential steering. The control framework and relevant models are first established. An upper-layer model predictive control (MPC) controller is then designed to simultaneously achieve lateral path tracking and longitudinal speed regulation, outputting the desired front-wheel steering angle and acceleration. Finally, a model-free adaptive control (MFAC)-based lower-layer lateral controller transforms the desired steering angle into differential driving torques for the front wheels, while a feedforward–feedback lower-layer longitudinal controller (incorporating drive/brake switching and PI control) computes the required driving torque or braking pressure. Co-simulation in Matlab/Simulink R2022b and CarSim R2020 reveals that the MPC controller designed in this study outperforms the LQR-PID controller, reducing the maximum absolute values of lateral error, heading error, front-wheel steering angle, yaw rate and sideslip angle by 42.9%, 50.0%, 7.8%, 2.8% and 10.3%. The proposed hierarchical control strategy outperforms the compared hierarchical controller, reducing the maximum absolute values of the lateral displacement error, heading error and yaw rate by 17.9%, 6.7%, and 33.3%. These results verify that the strategy can improve trajectory tracking accuracy and achieve basic differential steering functionality in specific scenarios. Full article

(This article belongs to the Special Issue Actuator Fault Diagnosis, State Detection and Fault Tolerant Control for Ground and Rail Vehicles)

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32 pages, 5604 KB

Open AccessArticle

Dual-Layer LAMDA-Based Cascade Control for Cooperative Formation of Aerial Manipulators

by Gabriela M. Andaluz, Luis Morales, Paulo Leica and Guillermo Palacios-Navarro

Actuators 2026, 15(4), 204; https://doi.org/10.3390/act15040204 - 4 Apr 2026

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Abstract

This paper proposes a novel dual-layer learning-based cascade architecture, termed LAMDA-LAMDA, for cooperative formation control of aerial manipulators. The strategy integrates two hierarchical LAMDA controllers: an inner loop that performs velocity-level dynamic compensation and disturbance attenuation, and an outer loop that regulates formation [...] Read more.

This paper proposes a novel dual-layer learning-based cascade architecture, termed LAMDA-LAMDA, for cooperative formation control of aerial manipulators. The strategy integrates two hierarchical LAMDA controllers: an inner loop that performs velocity-level dynamic compensation and disturbance attenuation, and an outer loop that regulates formation shape and centroid tracking. Unlike conventional model-dependent approaches, the proposed control law does not require explicit knowledge of the aerial manipulator dynamics, which are characterized by strong nonlinear coupling between the hexacopter platform and the onboard manipulator. A Lyapunov-based stability analysis guarantees asymptotic convergence of both velocity and formation errors under bounded uncertainties. The controller is benchmarked against four reference schemes: Kinematic-SMC, SMC with Inverse Dynamics (SMC-ID), SMC-SMC cascade, SMC-LAMDA, and LAMDA-LAMDA cascade, considering abrupt reference changes and severe parametric disturbances affecting inertia, Coriolis, and gravitational terms. Quantitative results show that LAMDA-LAMDA achieves the lowest tracking errors, with average ISE = 0.702 and IAE = 1.652, corresponding to improvements of 35.3% and 32.1% over the best model-based alternative. Additionally, the proposed scheme generates smooth control actions while preserving robustness, highlighting its suitability for cooperative aerial manipulation under dynamic uncertainty. Full article

(This article belongs to the Section Control Systems)

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18 pages, 7179 KB

Open AccessArticle

Research on Error Compensation of MTPA Control for Synchronous Reluctance Motors

by Shengjie Fu, Chuanqiang Zhang, Zhaoyuan Yao, Qihuai Chen and Tianliang Lin

Actuators 2026, 15(4), 203; https://doi.org/10.3390/act15040203 - 3 Apr 2026

Viewed by 267

Abstract

Synchronous Reluctance Motors (SynRM) have attracted much attention due to their advantages of simple structure and low cost. However, due to factors such as magnetic saturation and temperature changes, the parameters of SynRM exhibit nonlinear characteristics. Existing Maximum Torque per Ampere (MTPA) control [...] Read more.

Synchronous Reluctance Motors (SynRM) have attracted much attention due to their advantages of simple structure and low cost. However, due to factors such as magnetic saturation and temperature changes, the parameters of SynRM exhibit nonlinear characteristics. Existing Maximum Torque per Ampere (MTPA) control strategies often do not fully consider the impact of nonlinear changes in motor parameters, making it difficult to achieve accurate MTPA control and resulting in reduced motor efficiency. This article analyzes the control errors caused by the nonlinear changes in inductance of SynRM and proposes an error compensation strategy based on virtual DC signal injection MTPA control. The error expression is reconstructed to achieve error compensation and improve the accuracy of MTPA control. The effectiveness of the proposed control strategy is verified by building a simulation model and a motor experimental platform. The experimental results show that the control strategy proposed in this paper can achieve a maximum current optimization rate of 5.01% while ensuring fast system responsiveness. Full article

(This article belongs to the Section Control Systems)

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17 pages, 2787 KB

Open AccessArticle

Research on Impedance Matching Performance Evaluation Method for Ultrasonic Machining System Based on Standing Wave Detection

by Nanchao Jiang, Hongxian Ye, Shixi Yang and Baohua Yu

Actuators 2026, 15(4), 202; https://doi.org/10.3390/act15040202 - 2 Apr 2026

Viewed by 385

Abstract

The failure of impedance matching between the ultrasonic power supply and the transducer can degrade machining quality, decrease machining efficiency, and reduce tool life. To enhance the detection efficiency of impedance matching status in ultrasonic machining systems, an impedance matching detection method based [...] Read more.

The failure of impedance matching between the ultrasonic power supply and the transducer can degrade machining quality, decrease machining efficiency, and reduce tool life. To enhance the detection efficiency of impedance matching status in ultrasonic machining systems, an impedance matching detection method based on the Voltage Standing Wave Ratio (VSWR) is proposed. First, by constructing a fitting model for the forward and reverse voltage and power of ultrasonic power supply, the relationship between VSWR and voltage is determined. Subsequently, a correlation model between the VSWR and tool tip amplitude, which reflects the working state of the ultrasonic system, is established. And the range of VSWR for optimal performance of system impedance matching is obtained by means of the model. Finally, the detection effectiveness of this method is verified through experiments on tool tip output amplitude under varying working conditions, and a comparison is made between this method and the phase method. The results indicate that using VSWR as a detection parameter to characterize impedance matching yields measurement values within 7% of the theoretical values. These results confirm the evaluation interval for a good working state of the system. Furthermore, experiments under varying force loads and temperatures demonstrate the reliability of the VSWR-based characterization. Compared to the traditional phase method, this approach reduces the cost of impedance matching performance detection and meets the requirements for impedance matching status detection during ultrasonic machining. Full article

(This article belongs to the Section Actuators for Manufacturing Systems)

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14 pages, 1266 KB

Open AccessArticle

An Enhanced Envelope Spectroscopy Method for Bearing Diagnosis: Coupling PSO-Adaptive Stochastic Resonance with LMD

by Zhaohong Wu, Jin Xu, Jiaxin Wei, Haiyang Wu, Yusong Pang, Chang Liu and Gang Cheng

Actuators 2026, 15(4), 201; https://doi.org/10.3390/act15040201 - 2 Apr 2026

Viewed by 351

Abstract

Early fault vibration signals from rolling bearings are typically nonlinear, non-stationary, and heavily obscured by background noise, which severely impedes the accurate extraction of fault features. To overcome the limitations of traditional stochastic resonance (SR)—specifically the small-parameter restriction for high-frequency signals and the [...] Read more.

Early fault vibration signals from rolling bearings are typically nonlinear, non-stationary, and heavily obscured by background noise, which severely impedes the accurate extraction of fault features. To overcome the limitations of traditional stochastic resonance (SR)—specifically the small-parameter restriction for high-frequency signals and the subjectivity in parameter selection—this paper proposes an adaptive SR envelope spectroscopy method based on particle swarm optimization (PSO) and local mean decomposition (LMD). First, a variable-scale transformation is introduced to compress the high-frequency fault signals into the effective frequency band required by the adiabatic approximation theory. Second, utilizing the global search capability of PSO, the potential well parameters of the bistable system are adaptively optimized by maximizing the output signal-to-noise ratio (SNR), thereby achieving optimal matching between the nonlinear system and the input signal. Finally, the enhanced signal is decomposed by LMD, and the sensitive components are selected for envelope spectrum analysis to identify fault characteristics. Experimental validation using the Case Western Reserve University bearing dataset demonstrates that the proposed method effectively amplifies weak fault signals under strong noise conditions, exhibiting superior feature extraction accuracy and noise robustness compared to traditional methods. Full article

(This article belongs to the Section Control Systems)

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19 pages, 11080 KB

Open AccessArticle

A Fast Reaching Law in Sliding Mode Control with Application to an Inverted Pendulum Robot

by Dongliang Wang, Guofu Ma and Zhun Fan

Actuators 2026, 15(4), 200; https://doi.org/10.3390/act15040200 - 2 Apr 2026

Viewed by 390

Abstract

Sliding mode control (SMC) is an effective and robust technique for managing uncertain nonlinear systems. The conventional SMC approach integrates a constant-rate reaching law with the boundary layer method to regulate the system. However, it does not address scenarios in which the initial [...] Read more.

Sliding mode control (SMC) is an effective and robust technique for managing uncertain nonlinear systems. The conventional SMC approach integrates a constant-rate reaching law with the boundary layer method to regulate the system. However, it does not address scenarios in which the initial state variables are significantly distant from the boundary layer. To expedite the process of reaching the sliding surface, this study introduces a fast reaching law in SMC, ensuring a fixed control time for reaching the sliding mode surface. The proposed fast reaching law is applied to an inverted pendulum robot, demonstrating its effectiveness in this typical system. In addition, we propose a qualitative evaluation method to compare various existing reaching law methods. The simulation results indicate that the proposed reaching law outperforms current approaches, substantiating its effectiveness. Full article

(This article belongs to the Special Issue Analysis and Design of Linear/Nonlinear Control System—2nd Edition)

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Actuators, Volume 15, Issue 4 (April 2026) – 53 articles

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