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Actuators, Volume 13, Issue 3 (March 2024) – 37 articles

Cover Story (view full-size image): An electric coolant control valve has become prominent because optimal control of coolant temperature is essential to maintain the performance of a fuel cell vehicle. Therefore, this study investigated the transient dynamic flow characteristics of the fluid flow via a five-way electric coolant valve. To achieve this goal, this paper attempts a 3D CFD simulation of the fluid flow through the valve using a moving-grid technique to consider flow inertia and dynamic flow in the opening and closing stages of the ball valve rotating motion. Via comparisons of steady and dynamic flow simulations for two different rotation speeds and directions, it is found that thermo-fluid characteristics are greatly dependent on the rotational speed, rotational direction, and flow interference between fluxes. View this paper
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20 pages, 2874 KiB  
Article
Multi-Channel Phase-Compensated Active Disturbance Rejection Control with an Improved Backstepping Strategy for Electro-Optical Tracking Systems
by Shanlin Zhuang, Jiachen Li, Haolin Wang, Jiuqiang Deng and Yao Mao
Actuators 2024, 13(3), 117; https://doi.org/10.3390/act13030117 - 21 Mar 2024
Viewed by 711
Abstract
A multi-channel phase-compensated active disturbance rejection control (MPADRC) incorporating an improved backstepping strategy is proposed in this paper to handle the phase lag in the extended state observer (ESO) and the residual uncertainty in the system. Firstly, a multi-channel phase-compensated ESO (MPESO) is [...] Read more.
A multi-channel phase-compensated active disturbance rejection control (MPADRC) incorporating an improved backstepping strategy is proposed in this paper to handle the phase lag in the extended state observer (ESO) and the residual uncertainty in the system. Firstly, a multi-channel phase-compensated ESO (MPESO) is constructed by adding phase-advanced networks to all output channels of the ESO, which allows disturbances and system states to be compensated and feedback in a more timely manner, respectively. Then, to estimate and offset the residual uncertainty in the system, an improved backstepping control method is employed and a Lyapunov function is designed to verify the convergence of the error between the estimated and actual values of the residual uncertainty. After that, the improved backstepping control is combined with MPADRC, and comparisons with the conventional linear active disturbance rejection control (LADRC) are conducted for a range of cases. Finally, on an inertial stabilization platform in the electro-optical tracking system (ETS), simulation and experimental results verified the effectiveness of the proposed method. Full article
(This article belongs to the Section Control Systems)
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15 pages, 3298 KiB  
Article
Self-Stabilizing Control Strategy of Stabilized Platform for Rotary Steerable Drilling System Based on Adaptive Backstepping Control
by Shuoyu Li, Yuelong Wang, Xiaoxiong Wu, Yanhui Mao, Jia Chen and Yi Yang
Actuators 2024, 13(3), 116; https://doi.org/10.3390/act13030116 - 20 Mar 2024
Viewed by 671
Abstract
To enhance the robustness of the toolface angle control in a fully rotary steerable drilling tool, a backstepping control law and a drilling fluid flow adaptive law are devised based on the dynamic model of the stable platform. The Lyapunov function is constructed, [...] Read more.
To enhance the robustness of the toolface angle control in a fully rotary steerable drilling tool, a backstepping control law and a drilling fluid flow adaptive law are devised based on the dynamic model of the stable platform. The Lyapunov function is constructed, and it is proven that the adaptive backstepping control system of the stabilized platform is stable. Furthermore, in order to address problems such as the friction dead zone and excessive rotational kinetic energy in the stabilized platform system, which could cause toolface angle oscillations and the rapid rotation of the stabilized platform, we additionally propose an online estimation method for the balancing torque and velocity-angle control switching strategy. By combining the backstepping control law, drilling fluid flow adaptive law, and velocity-angle control switching strategy, a self-stabilizing control strategy for the stabilized platform is established. In comparison with the PID control method, the simulation results show the superiority of the proposed scheme under complex disturbances from a downhole environment. And the drilling simulation experiment results indicate that the proposed control method has a good anti-interference capability under various conditions, including drilling fluid flow rate, inclination angle, and drill collar rotational speed. Therefore, the proposed control method can improve the robustness of the stabilized platform control system. Full article
(This article belongs to the Section Control Systems)
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13 pages, 6017 KiB  
Article
On the Evolution of Stress and Microstructure in Radio Frequency-Sputtered Lead-Free (Ba,Ca)(Zr,Ti)O3 Thin Films
by Runar Plünnecke Dahl-Hansen, Marit Synnøve Sæverud Stange, Tor Olav Sunde, Johan Henrik Ræder and Per Martin Rørvik
Actuators 2024, 13(3), 115; https://doi.org/10.3390/act13030115 - 20 Mar 2024
Viewed by 673
Abstract
Thin-film piezoelectrics are widely investigated for actuators and energy harvesters, but there are few alternatives to toxic lead zirconate titanate. Biocompatible Ca- and Zr-modified BaTiO3 (BCZT) is one of the most promising lead-free alternatives due to its high piezoelectric response. However, the [...] Read more.
Thin-film piezoelectrics are widely investigated for actuators and energy harvesters, but there are few alternatives to toxic lead zirconate titanate. Biocompatible Ca- and Zr-modified BaTiO3 (BCZT) is one of the most promising lead-free alternatives due to its high piezoelectric response. However, the dielectric/piezoelectric properties and structural integrity of BCZT films, which are crucial for their applications, are strongly influenced by the substrate upon which the film is grown and the related processing methods. Here, the in-plane stress, microstructure, dielectric, and piezoelectric properties of 100–500 nm thick high-temperature RF-sputtered BCZT films on industrially relevant Si-based substrates were investigated. Obtaining polycrystalline piezoelectric films required deposition temperatures ≥ 700 °C, but this induced tensile stresses of over 1500 MPa, which caused cracking in all films thicker than 200 nm. This degraded the dielectric, piezoelectric, and ferroelectric properties of films with larger electrode areas for applications. Films on SrTiO3, on the other hand, had a compressive residual stress, with fewer defects and no cracks. The grain size and surface roughness increased with increasing deposition temperature. These findings highlight the challenges in processing BCZT films and their crucial role in advancing lead-free piezoelectric technologies for actual device applications. Full article
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31 pages, 51418 KiB  
Article
Reaction Force-Based Position Sensing for Magnetic Levitation Platform with Exceptionally Large Hovering Distance
by Reto Bonetti, Lars Beglinger, Spasoje Mirić, Dominik Bortis and Johann W. Kolar
Actuators 2024, 13(3), 114; https://doi.org/10.3390/act13030114 - 16 Mar 2024
Viewed by 858
Abstract
This work introduces a novel sensing concept based on reaction forces for determining the position of the levitating magnet (mover) for magnetic levitation platforms (MLPs). Besides being effective in conventional magnetic bearings, the applied approach enables operation in systems where the mover is [...] Read more.
This work introduces a novel sensing concept based on reaction forces for determining the position of the levitating magnet (mover) for magnetic levitation platforms (MLPs). Besides being effective in conventional magnetic bearings, the applied approach enables operation in systems where the mover is completely isolated from the actuating electromagnets (EMs) of the stator (e.g., located inside a sealed process chamber) while levitating at an extreme levitation height. To achieve active position control of the levitating mover by properly controlling the stator’s EM currents, it is necessary to employ a dynamic model of the complete MLP, including the reaction force sensor, and implement an observer that extracts the position from the force-dependent signals, given that the position is not directly tied to the measured forces. Furthermore, two possible controller implementations are discussed in detail: a basic PID controller and a more sophisticated state-space controller that can be chosen depending on the characteristics of the MLP and the accuracy of the employed sensing method. To show the effectiveness of the proposed position-sensing and control concept, a hardware demonstrator employing a 207 mm outer-diameter (characteristic dimension, CD) stator with permanent magnets, a set of electromagnets, and a commercial multi-axis force sensor is built, where a 0.36 kg mover is stably levitated at an extreme air gap of 104 mm. Full article
(This article belongs to the Special Issue Actuators in 2024)
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13 pages, 13431 KiB  
Article
Extended State Kalman Filter-Based Model Predictive Control for Electro-Optical Tracking Systems with Disturbances: Design and Experimental Verification
by Wanrun Xia, Yao Mao, Luyao Zhang, Tong Guo, Haolin Wang and Qiliang Bao
Actuators 2024, 13(3), 113; https://doi.org/10.3390/act13030113 - 16 Mar 2024
Viewed by 727
Abstract
A modified Extended State Kalman Filter (ESKF)-based Model Predictive Control (MPC) algorithm is introduced to tailor the enhanced disturbance suppression in electro-optical tracking systems. Traditional control techniques, although robust, often struggle in scenarios with concurrent internal, external disturbances, and sensor noise. The proposed [...] Read more.
A modified Extended State Kalman Filter (ESKF)-based Model Predictive Control (MPC) algorithm is introduced to tailor the enhanced disturbance suppression in electro-optical tracking systems. Traditional control techniques, although robust, often struggle in scenarios with concurrent internal, external disturbances, and sensor noise. The proposed algorithm effectively overcomes these limitations by precisely estimating system states and actively mitigating disturbances, thus significantly boosting noise and perturbation control resilience. The primary contributions of this study include the integration of ESKF for accurate system state and disturbance estimation in noisy environments, the embedding of an ESKF estimation-compensation loop to simulate an improved disturbance-free system, and a simplified modeling approach for the controlled device. This designed structure minimizes the reliance on extensive system identification, easing the predictive control model-based constraints. Moreover, the approach incorporates total disturbance estimation into the optimization problem, safeguarding against actuator damage and ensuring high tracking accuracy. Through rigorous simulations and experiments, the ESKF-based MPC has demonstrated enhanced model error tolerance and superior disturbance suppression capabilities. Comparative analyses under varying model parameters and external disturbances highlight its exceptional trajectory tracking performance, even in the presence of model uncertainties and external noise. Full article
(This article belongs to the Section Control Systems)
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17 pages, 38360 KiB  
Article
Design and Characterization of Soft Fabric Omnidirectional Bending Actuators
by Kyungjoon Lee, Khulan Bayarsaikhan, Gabriel Aguilar, Jonathan Realmuto and Jun Sheng
Actuators 2024, 13(3), 112; https://doi.org/10.3390/act13030112 - 14 Mar 2024
Viewed by 889
Abstract
Soft robots, inspired by biological adaptability, can excel where rigid robots may falter and offer flexibility and safety for complex, unpredictable environments. In this paper, we present the Omnidirectional Bending Actuator (OBA), a soft robotic actuation module which is fabricated from off-the-shelf materials [...] Read more.
Soft robots, inspired by biological adaptability, can excel where rigid robots may falter and offer flexibility and safety for complex, unpredictable environments. In this paper, we present the Omnidirectional Bending Actuator (OBA), a soft robotic actuation module which is fabricated from off-the-shelf materials with easy scalability and consists of three pneumatic chambers. Distinguished by its streamlined manufacturing process, the OBA is capable of bending in all directions with a high force-to-weight ratio, potentially addressing a notable research gap in knit fabric actuators with multi-degree-of-freedom capabilities. We will present the design and fabrication of the OBA, examine its motion and force capabilities, and demonstrate its capability for stiffness modulation and its ability to maintain set configurations under loads. The mass of the entire actuation module is 278 g, with a range of omnidirectional bending up to 90.80°, a maximum tolerable pressure of 862 kPa, and a bending payload (block force) of 10.99 N, resulting in a force-to-weight ratio of 39.53 N/kg. The OBA’s cost-effective and simple fabrication, compact and lightweight structure, and capability to withstand high pressures present it as an attractive actuation primitive for applications demanding efficient and versatile soft robotic solutions. Full article
(This article belongs to the Special Issue Soft Robotics: Actuation, Control, and Application)
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17 pages, 9375 KiB  
Article
Model Predictive Control Strategy Based on Loss Equalization for Three-Level ANPC Inverters
by Shaoqi Wan, Bo Wang, Jingbo Chen, Haiying Dong and Congxin Lv
Actuators 2024, 13(3), 111; https://doi.org/10.3390/act13030111 - 12 Mar 2024
Viewed by 698
Abstract
Targeting the issue of high losses of individual switching tubes in Neutral-Point Clamped (NPC) three-level inverters, an Active Neutral-Point Clamped (ANPC) three-level inverter is used, and a model predictive control strategy using the loss equalization of the inverter is proposed. This method organizes [...] Read more.
Targeting the issue of high losses of individual switching tubes in Neutral-Point Clamped (NPC) three-level inverters, an Active Neutral-Point Clamped (ANPC) three-level inverter is used, and a model predictive control strategy using the loss equalization of the inverter is proposed. This method organizes and analyzes multiple zero-state current pathway commutation modes and adds mode three under the original two commonly used zero-state commutation modes. On this basis, the three modes are flexibly switched by model predictive control, and the output is optimized according to the value function for the space vector in each operation, while the midpoint voltage control is added to the value function. The simulation results suggest that the recommended strategy in this study may effectively realize the loss equalization control and midpoint voltage control of the ANPC inverter, which improves the operation efficiency of the electromechanical actuator. Full article
(This article belongs to the Special Issue Power Electronics and Actuators)
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21 pages, 17164 KiB  
Article
Transient and Dynamic Simulation of the Fluid Flow through Five-Way Electric Coolant Control Valve of a 100 kW Fuel Cell Vehicle by CFD with Moving Grid Technique
by Soo-Jin Jeong, Ji-hoon Kang, Seong-Joon Moon and Gum-su Lee
Actuators 2024, 13(3), 110; https://doi.org/10.3390/act13030110 - 11 Mar 2024
Viewed by 795
Abstract
In order to maintain the performance of a fuel cell vehicle, it is essential to maintain a constant temperature of the stack. Therefore, it is very important to distribute the optimal coolant flow rate to each major component under very diverse and rapidly [...] Read more.
In order to maintain the performance of a fuel cell vehicle, it is essential to maintain a constant temperature of the stack. Therefore, it is very important to distribute the optimal coolant flow rate to each major component under very diverse and rapidly changing dynamic operating conditions. The part responsible for this is a five-way electric coolant valve. Therefore, this study aims to investigate transient dynamic flow characteristics of the fluid flow through a five-way electric coolant valve (PCCV: Penta-Control Coolant Valve). To achieve this goal, this paper attempts a three-dimensional dynamic simulation of the fluid flow through the valve using a commercial CFD solver with moving mesh technique to consider flow inertia and dynamic flow in the opening and closing stages of the ball valve rotating motion. The dynamic flow characteristics and the thermal mixing inside the PCCV ball valve during the opening and closing stages are analyzed. It was found that the discrepancies between dynamic and steady-state simulations are remarkable when fluxes with different levels of enthalpy and momentum flow into the PCCV, leading to strong flow interference and flow inertia, while the discrepancies are relatively small at low rotation speed and weak flow interference. Subsequently, the effect of the dynamic flow characteristics of the valve on the dynamic thermal mixing characteristics at two different ball valve rotation speeds and rotation directions are investigated. It was found that the dynamic flow and thermal mixing characteristics inside the PCCV are greatly affected by the rotation speed, rotation direction, and degree of flow interference between fluxes. It also helps design better coolant control strategies and improves the FCEV thermal management system. Full article
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20 pages, 7690 KiB  
Article
Trajectory Re-Planning and Tracking Control for a Tractor–Trailer Mobile Robot Subject to Multiple Constraints
by Tianrui Zhao, Peibo Li, Yu Yuan, Lin Zhang and Yanzheng Zhao
Actuators 2024, 13(3), 109; https://doi.org/10.3390/act13030109 - 08 Mar 2024
Viewed by 799
Abstract
Autonomous tractor–trailer robots possess a broad spectrum of applications but pose significant challenges in control due to their nonlinear and underactuated dynamics. Unlike the tractor, the motion of the trailer cannot be directly actuated, which often results in a deviation from the intended [...] Read more.
Autonomous tractor–trailer robots possess a broad spectrum of applications but pose significant challenges in control due to their nonlinear and underactuated dynamics. Unlike the tractor, the motion of the trailer cannot be directly actuated, which often results in a deviation from the intended path. In this study, we introduce a novel method for generating and following trajectories that circumvent obstacles, tailored for a tractor–trailer robotic system constrained by multiple factors. Firstly, leveraging the state information of both the obstacles and the desired trajectory, we formulate an improved trajectory for obstacle avoidance using the nonlinear least squares method. Subsequently, we propose an innovative tracking controller that integrates a universal barrier function with a state transformation strategy. This amalgamation facilitates the accurate tracking of the prescribed trajectory. Our theoretical analysis substantiates that the proposed control methodology ensures exponential convergence of the line-of-sight (LOS) distance and angle tracking errors, while enhancing the transient performance. To validate the efficacy of our approach, we present a series of simulation results, which demonstrate the applicability of the developed control strategy in managing the complex dynamics of tractor–trailer robots. Full article
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24 pages, 5847 KiB  
Article
Trajectory Generation Method for Serial Robots in Hybrid Space Operations
by Yan Xu, Yaqiu Liu, Xun Liu, Yiyang Zhao, Peibo Li and Pengjie Xu
Actuators 2024, 13(3), 108; https://doi.org/10.3390/act13030108 - 08 Mar 2024
Viewed by 810
Abstract
The hybrid space of robots is divided into task space and joint space, with task space focused on trajectory-tracking accuracy, while joint space considers dynamic responsiveness and synchronization. Therefore, the robot-motion control systems need to effectively integrate both aspects, ensuring precision in task [...] Read more.
The hybrid space of robots is divided into task space and joint space, with task space focused on trajectory-tracking accuracy, while joint space considers dynamic responsiveness and synchronization. Therefore, the robot-motion control systems need to effectively integrate both aspects, ensuring precision in task trajectory while promptly responding to unforeseen environmental events. Hence, this paper proposes an online trajectory-generation method for robots in both joint and task spaces. In task space, a planning approach is presented for high-precision NURBS curves. The global NURBS curve is segmented into several rational Bezier curves, establishing local coordinate systems for control points. This ensures that all local control points meet the chord error constraint, guaranteeing trajectory accuracy. To address the feed rate dynamic planning issue for segmented curves, an improved online S-shape feed-rate scheduling framework is introduced. This framework dynamically adjusts the current execution speed to meet task requirements. In joint space, an offline velocity planning based on a time synchronization scheme and a multi-dimensional synchronization technique based on the principle of spatial-coordinate system projection are proposed. Building upon the offline scheme, it allows for the modification of the target state for any sub-dimension during the motion process, with the remaining dimensions adapting accordingly. Simulation and experimentation demonstrate that the two proposed online trajectory generations for robot motion spaces, while ensuring task trajectory accuracy, effectively handle external unexpected events. They ensure joint synchronization and smoothness, carrying significant practical implications and application value for the stability of robot systems. Full article
(This article belongs to the Special Issue Motion Planning and Control of Robot Systems)
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17 pages, 6233 KiB  
Article
Design of an Electromagnetic Linear Drive with Permanent Magnetic Weight Compensation
by Bela Schulte Westhoff and Jürgen Maas
Actuators 2024, 13(3), 107; https://doi.org/10.3390/act13030107 - 08 Mar 2024
Viewed by 771
Abstract
When using electric linear drives for vertical positioning of workloads, a constant force both during movement and at standstill must be supplied to compensate gravity. Compensating stationary forces by the use of passive components reduces the power consumption of the employed actuator and [...] Read more.
When using electric linear drives for vertical positioning of workloads, a constant force both during movement and at standstill must be supplied to compensate gravity. Compensating stationary forces by the use of passive components reduces the power consumption of the employed actuator and permits smaller dimensioning. In this article, we present a novel integrative actuator design which combines the inherent advantages of a permanent magnetic weight compensation with a two-phase linear direct drive. We illustrate how to design permanent magnetic force compensation to realize a constant compensating force over a desired actuator stroke. Analytical solutions for both the design of the direct drive and the design of the permanent magnetic weight compensation are derived and validated by simulation and experiment. The innovative actuator design is compared to a conventional, non-compensated drive, and we aim to provide the reader with insights into specific applications where the use of the weight-compensated actuator proves particularly effective. Full article
(This article belongs to the Section Actuator Materials)
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12 pages, 4749 KiB  
Article
Numerical and Experimental Study of Low-Frequency Membrane Damper for Tube Vibration Suppression
by Boris I and Jaesun Lee
Actuators 2024, 13(3), 106; https://doi.org/10.3390/act13030106 - 08 Mar 2024
Viewed by 922
Abstract
In modern days, low-frequency vibration is still challenging to suppress due to its high vibrational energy. A typical suppression method is to increase the object’s mass to reduce the amplitude of the vibration, but such a way is unsuitable in many cases. Membrane [...] Read more.
In modern days, low-frequency vibration is still challenging to suppress due to its high vibrational energy. A typical suppression method is to increase the object’s mass to reduce the amplitude of the vibration, but such a way is unsuitable in many cases. Membrane dampers can potentially eliminate the limitation and offer lightweight and compact damper. The idea is to decrease the stiffness and add additional mass to increase the dissipation of the vibration energy. For that, the membrane and an extra mass made of silicone rubber were used for the damper. Finite element eigenfrequency simulation showed the transformation of each mode to the damper mode, where the tube displacement was zero. Also, it showed the bandgap between modes in the frequency range from 106 Hz to 158 Hz. The experimental verification of clamped from both ends of the tube showed the predicted bandgap and absence of the resonance peak of the bare tube. Overall, the membrane damper showed good efficiency in extremely low frequencies and seems promising for vibration suppression. Full article
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13 pages, 4144 KiB  
Article
High-Precision Position Tracking Control with a Hysteresis Observer Based on the Bouc–Wen Model for Smart Material-Actuated Systems
by Jubo Zhao, Yaobin Li, Yonggang Cao, Fukai Zhang, Ming Cui and Rui Xu
Actuators 2024, 13(3), 105; https://doi.org/10.3390/act13030105 - 07 Mar 2024
Viewed by 801
Abstract
The Bouc–Wen model has been widely adopted to describe hysteresis nonlinearity in many smart material-actuated systems, such as piezoelectric actuators, shape memory alloy actuators, and magnetorheological dampers. For effective control design, it is of interest to estimate the hysteresis state that is not [...] Read more.
The Bouc–Wen model has been widely adopted to describe hysteresis nonlinearity in many smart material-actuated systems, such as piezoelectric actuators, shape memory alloy actuators, and magnetorheological dampers. For effective control design, it is of interest to estimate the hysteresis state that is not measurable. In this paper, the design of a state observer for the Bouc–Wen model is presented. It is shown that, with sufficiently high observer gains, the state estimate error, including that for the hysteresis state, converges to zero exponentially fast. The utility of the proposed hysteresis observer is illustrated in the design of a high precision output-feedback position tracking controller, and the resulting tracking error is shown to decay exponentially via Lyapunov analysis. Simulation and experimental results show that the proposed hysteresis observer and the high precision position tracking controller outperform a traditional extended state observer and the corresponding tracking controller, respectively. Full article
(This article belongs to the Special Issue Advances in Smart Materials-Based Actuators)
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17 pages, 5077 KiB  
Article
Exploring Control Authority Preferences in Robotic Arm Assistance for Power Wheelchair Users
by Breelyn Kane Styler, Wei Deng, Reid Simmons, Henny Admoni, Rory Cooper and Dan Ding
Actuators 2024, 13(3), 104; https://doi.org/10.3390/act13030104 - 07 Mar 2024
Viewed by 846
Abstract
This paper uses mixed methods to explore the preliminary design of control authority preferences for an Assistive Robotic Manipulator (ARM). To familiarize users with an intelligent robotic arm, we perform two kitchen task iterations: one with user-initiated software autonomy (predefined autonomous actions) and [...] Read more.
This paper uses mixed methods to explore the preliminary design of control authority preferences for an Assistive Robotic Manipulator (ARM). To familiarize users with an intelligent robotic arm, we perform two kitchen task iterations: one with user-initiated software autonomy (predefined autonomous actions) and one with manual control. Then, we introduce a third scenario, enabling users to choose between manual control and system delegation throughout the task. Results showed that, while manually switching modes and controlling the arm via joystick had a higher mental workload, participants still preferred full joystick control. Thematic analysis indicates manual control offered greater freedom and sense of accomplishment. Participants reacted positively to the idea of an interactive assistive system. Users did not want to ask the system to only assist, by taking over for certain actions, but also asked for situational feedback (e.g., ‘How close am I (the gripper)?’, ‘Is the lid centered over the jug?’). This speaks to a future assistive system that ensures the user feels like they drive the system for the entirety of the task and provides action collaboration in addition to more granular situational awareness feedback. Full article
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21 pages, 849 KiB  
Article
Yaw Stability Control of Unmanned Emergency Supplies Transportation Vehicle Considering Two-Layer Model Predictive Control
by Minan Tang, Yaqi Zhang, Wenjuan Wang, Bo An and Yaguang Yan
Actuators 2024, 13(3), 103; https://doi.org/10.3390/act13030103 - 06 Mar 2024
Viewed by 774
Abstract
The transportation of emergency supplies is characterized by real-time, urgent, and non-contact, which constitute the basic guarantee for emergency rescue and disposal. To improve the yaw stability of the four-wheel-drive unmanned emergency supplies transportation vehicle (ESTV) during operation, a two-layer model predictive controller [...] Read more.
The transportation of emergency supplies is characterized by real-time, urgent, and non-contact, which constitute the basic guarantee for emergency rescue and disposal. To improve the yaw stability of the four-wheel-drive unmanned emergency supplies transportation vehicle (ESTV) during operation, a two-layer model predictive controller (MPC) method based on a Kalman filter is proposed in this paper. Firstly, the dynamics model of the ESTV is established. Secondly, the improved Sage–Husa adaptive extended Kalman filter (SHAEKF) is used to decrease the impact of noise on the ESTV system. Thirdly, a two-layer MPC is designed for the yaw stability control of the ESTV. The upper-layer controller solves the yaw moment and the front wheel steering angle of the ESTV. The lower-layer controller optimizes the torque distribution of the four tires of the ESTV to ensure the self-stabilization of the ESTV operation. Finally, analysis and verification are carried out. The simulation results have verified that the improved SHAEKF can decrease the state estimation error by more than 78% and achieve the noise reduction of the ESTV state. Under extreme conditions of high velocity and low adhesion, the average relative error is within 6.77%. The proposed control method can effectively prevent the instability of the ESTV and maintain good yaw stability. Full article
(This article belongs to the Special Issue Integrated Intelligent Vehicle Dynamics and Control)
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16 pages, 3435 KiB  
Article
Design and Evaluation of the Sit-to-Stand Movement Assistive Device for Elderly
by Yicun Xu, Bo Zhang, Yongzhen Li, Ruihua Guo, Pei Cao, Xiaofeng Zhu and Shangkai Zhu
Actuators 2024, 13(3), 102; https://doi.org/10.3390/act13030102 - 05 Mar 2024
Viewed by 839
Abstract
The act of standing up is one of the most important movements in daily life, but it often poses challenges for elderly individuals with declining physical functions. To address this issue, we have designed an assistive device for sit-to-stand (STS) movement. This device [...] Read more.
The act of standing up is one of the most important movements in daily life, but it often poses challenges for elderly individuals with declining physical functions. To address this issue, we have designed an assistive device for sit-to-stand (STS) movement. This device aids the upper limbs, allowing them to bear some of the weight during the STS movement, thereby improving the force distribution on the lower limbs and enhancing the stability of the body during movement. The connection to the user is very straightforward; one simply needs to place their hands and arms on the lifting mechanism to connect, and after the STS movement is completed, the user can easily disengage, making it very convenient to use. The device is compact, equipped with wheels and a handle, allowing it to be flexibly moved and used in confined spaces such as bedrooms, bathrooms, and balconies. ADAMS-LifeMOD simulations indicate that the use of the STS movement assistive device can significantly improve the force distribution across the joints of the lower limbs and reduce the pressure on the soles of the feet against the ground. Subsequently, a prototype was built, and four volunteers were invited to conduct further experimental validation, comparing the changes in plantar pressure during the STS movement with and without the assistive device, as well as the subjective feelings of the users. The experimental results demonstrate that the device can effectively help users to stand up more easily. Full article
(This article belongs to the Special Issue Actuators in Assistive and Rehabilitation Robotics)
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16 pages, 4078 KiB  
Article
Deviation Sequence Neural Network Control for Path Tracking of Autonomous Vehicles
by Liang Su, Yiyuan Mao, Feng Zhang, Baoxing Lin and Yong Zhang
Actuators 2024, 13(3), 101; https://doi.org/10.3390/act13030101 - 05 Mar 2024
Viewed by 837
Abstract
Despite its excellent performance in path tracking control, the model predictive control (MPC) is limited by computational complexity in practical applications. The neural network control (NNC) is another attractive solution by learning the historical driving data to approximate optimal control law, but a [...] Read more.
Despite its excellent performance in path tracking control, the model predictive control (MPC) is limited by computational complexity in practical applications. The neural network control (NNC) is another attractive solution by learning the historical driving data to approximate optimal control law, but a concern is that the NNC lacks security guarantees when encountering new scenarios that it has never been trained on. Inspired by the prediction process of MPC, the deviation sequence neural network control (DS-NNC) separates the vehicle dynamic model from the approximation process and rebuilds the input of the neural network (NN). Taking full use of the deviation sequence architecture and the real-time vehicle dynamic model, the DS-NNC is expected to enhance the adaptability and the training efficiency of NN. Finally, the effectiveness of the proposed controller is verified through simulations in Matlab/Simulink. The simulation results indicate that the proposed path tracking NN controller possesses adaptability and learning capabilities, enabling it to generate optimal control variables within a shorter computation time and handle variations in vehicle models and driving scenarios. Full article
(This article belongs to the Section Actuators for Land Transport)
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22 pages, 4588 KiB  
Article
Dynamic Modeling, Simulation, and Optimization of Vehicle Electronic Stability Program Algorithm Based on Back Propagation Neural Network and PID Algorithm
by Zheng Wu, Cunfeng Kang, Borun Li, Jiageng Ruan and Xueke Zheng
Actuators 2024, 13(3), 100; https://doi.org/10.3390/act13030100 - 04 Mar 2024
Viewed by 1244
Abstract
The vehicle lateral stability control algorithm is an essential component of the electronic stability program (ESP), and its control effect directly affects the vehicle’s driving safety. However, there are still numerous shortcomings and challenges that need to be addressed, including enhancing the efficiency [...] Read more.
The vehicle lateral stability control algorithm is an essential component of the electronic stability program (ESP), and its control effect directly affects the vehicle’s driving safety. However, there are still numerous shortcomings and challenges that need to be addressed, including enhancing the efficiency of processing intricate pavement condition data, improving the accuracy of parameter adjustment, and identifying subtle and elusive patterns amidst noisy and ambiguous data. The introduction of machine learning algorithms can address the aforementioned issues, making it imperative to apply machine learning to the research of lateral stability control algorithms. This paper presented a vehicle lateral electronic stability control algorithm based on the back propagation (BP) neural network and PID control algorithm. Firstly, the dynamics of the whole vehicle have been analytically modeled. Then, a 2 DOF prediction model and a 14 DOF simulation model were built in MATLAB Simulink to simulate the data of the electronic control units (ECU) in ESP and estimate the dynamic performance of the real vehicle. In addition, the self-correction of the PID algorithm was verified by a Simulink/CarSim combined simulation. The improvement of the BP neural network to the traditional PID algorithm was also analyzed in Simulink. These simulation results show the self-correction of the PID algorithm on the lateral stability control of the vehicle under different road conditions and at different vehicle speeds. The BP neural network smoothed the vehicle trajectory controlled by traditional PID and improved the self-correction ability of the control system by iterative training. Furthermore, it shows that the algorithm can automatically tune the control parameters and optimize the control process of the lateral electronic stability control algorithm, thus improving vehicle stability and adapting it to many different vehicle models and road conditions. Therefore, the algorithm has a high practical value and provides a feasible idea for developing a more intelligent and general vehicle lateral electronic stability system. Full article
(This article belongs to the Section Actuators for Land Transport)
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6 pages, 167 KiB  
Editorial
New Control Schemes for Actuators
by Oscar Barambones, José Antonio Cortajarena and Patxi Alkorta
Actuators 2024, 13(3), 99; https://doi.org/10.3390/act13030099 - 01 Mar 2024
Viewed by 945
Abstract
An actuator is a device that moves or controls a mechanism, by turning a control signal into mechanical action, such as in an electric motor [...] Full article
(This article belongs to the Special Issue New Control Schemes for Actuators)
17 pages, 7139 KiB  
Article
Adaptive Nonsingular Fast-Reaching Terminal Sliding Mode Control Based on Observer for Aerial Robots
by Pu Yang, Yan Xuan and Wanting Li
Actuators 2024, 13(3), 98; https://doi.org/10.3390/act13030098 - 29 Feb 2024
Viewed by 969
Abstract
In this article, an observer-based adaptive non-singular fast-reaching terminal sliding mode control strategy is proposed to tackle the problem of actuator faults and uncertain disturbance in aerial robot systems. Firstly, a model of an aerial robot system is established through dynamic analysis. Next, [...] Read more.
In this article, an observer-based adaptive non-singular fast-reaching terminal sliding mode control strategy is proposed to tackle the problem of actuator faults and uncertain disturbance in aerial robot systems. Firstly, a model of an aerial robot system is established through dynamic analysis. Next, an adaptive observer, combined with a fast adaptive fault estimation (FAFE) algorithm, is proposed to estimate system states and actuator failure and compensate for faults in a precise and prompt manner. In addition, a non-singular fast terminal sliding surface is defined, taking into account the fast convergence of the tracking errors in order to provide appropriate trajectory tracking results. Since the upper bounds of the disturbances caused by the manipulator of the system in practice are unknown, the control approach may benefit from the addition of an adaptive control strategy that can suppress the influence of uncertain disturbances. The Lyapunov stability theory demonstrates that tracking errors are able to converge stably and quickly. In the end, the contrast experiment is conducted to exhibit the effectiveness of the proposed control strategy. The results demonstrate quicker convergence and improved estimating accuracy. Full article
(This article belongs to the Special Issue Fault-Tolerant Control for Unmanned Aerial Vehicles (UAVs))
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20 pages, 3841 KiB  
Article
Research on Path Tracking Fault-Tolerant Control Strategy for Intelligent Commercial Vehicles Based on Brake Actuator Failure
by Guanjie Cui, Chunjiang Bao, Mingjie Guo, Yahui Xu, Yelin He and Jian Wu
Actuators 2024, 13(3), 97; https://doi.org/10.3390/act13030097 - 28 Feb 2024
Viewed by 818
Abstract
With the development of safety technologies for intelligent commercial vehicles, electronic pneumatic braking systems (EBSs) have been widely used. However, EBS actuators may fail during vehicle operation and thus create safety problems. For this reason, we propose a path-tracking fault-tolerant control strategy under [...] Read more.
With the development of safety technologies for intelligent commercial vehicles, electronic pneumatic braking systems (EBSs) have been widely used. However, EBS actuators may fail during vehicle operation and thus create safety problems. For this reason, we propose a path-tracking fault-tolerant control strategy under EBS actuator failure in intelligent commercial vehicles. First, in order to be able to characterize different types of brake actuator faults during the EBS differential braking process of a vehicle, a comprehensive fault coefficient for calculating the degree of fault is designed, and a BES generalized fault model is established. Second, the faults are introduced into the fault-tolerant controller through the comprehensive fault coefficients for braking torque calculation and braking pressure allocation. Thus, a vehicle path model with the complete fault coefficients as variable parameters is established. Then, based on the LPV system gain scheduling, a path-tracking LPV/H∞ fault-tolerant controller under EBS actuator faults in commercial vehicles is designed, which is used to solve the safety problem arising from sudden EBS actuator faults. Finally, we conducted experimental validation through hardware-in-the-loop tests. The results demonstrate that the control strategy designed in this paper redistributes the braking torque and synergizes with the steering system to enhance vehicle stability, thereby improving vehicle safety in the EBS failure mode. Full article
(This article belongs to the Section Actuators for Land Transport)
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16 pages, 4216 KiB  
Article
Proposal for a Human–Machine Collaborative Transfer System Considering Caregivers’ Lower Back Pain and Cognitive Factors in the Elderly during Transfer Movements
by Jiang Wu and Motoki Shino
Actuators 2024, 13(3), 96; https://doi.org/10.3390/act13030096 - 28 Feb 2024
Viewed by 885
Abstract
With the aging society in Japan, the number of elderly people residing in elderly facilities is increasing. In previous study, we developed a transfer assistive device designed to aid the elderly in transferring from the bedroom to the bathroom. Additionally, the device assists [...] Read more.
With the aging society in Japan, the number of elderly people residing in elderly facilities is increasing. In previous study, we developed a transfer assistive device designed to aid the elderly in transferring from the bedroom to the bathroom. Additionally, the device assists the elderly with standing and sitting to facilitate independent toileting activities. We verified that, throughout the entire transfer movement, the lumbar burden on caregivers remained below 3400 N. In this study, based on quantitative evaluation indices of transfer movements, the relationship between the lumbar burden on caregivers and factors such as psychological anxiety or cognitive impairment in the elderly during the use of a transfer assistive device was elucidated through motion analysis. We developed a control algorithm for the human–machine collaborative transfer system with the aim of alleviating the strain on the caregiver’s lower back while ensuring the elderly can use the device with peace of mind. The practicality of the control algorithm was verified. Full article
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14 pages, 8720 KiB  
Article
A Microchannel Device for Droplet Classification by Manipulation Using Piezoelectric Vibrator
by Ao Fujioka, Shoko Seo, Takefumi Kanda, Shuichi Wakimoto and Daisuke Yamaguchi
Actuators 2024, 13(3), 95; https://doi.org/10.3390/act13030095 - 28 Feb 2024
Viewed by 873
Abstract
Emulsion formulations should be monodispersed in terms of their stability. Therefore, there is a need for a device that can classify droplets of the desired size from polydispersed emulsions in a fluidized bed manufacturing system. In the previous study, we evaluated the fabrication [...] Read more.
Emulsion formulations should be monodispersed in terms of their stability. Therefore, there is a need for a device that can classify droplets of the desired size from polydispersed emulsions in a fluidized bed manufacturing system. In the previous study, we evaluated the fabrication of a droplet manipulation device using acoustic radiation forces through simulation using the finite element method. In this study, particle manipulation experiments using 1, 6, and 10 µm polystyrene particles were first estimated and evaluated in comparison with their theoretical particle behavior. Based on the results we obtained, the driving conditions and droplet behavior were derived, and the droplet manipulation device using ultrasonic waves to shrink monodisperse emulsions was evaluated. As a result, the droplet classification effect in the microchannel was confirmed to be consistent with the droplet behavior prediction, and the microchannel structure with a constriction component improved its classification effect. Full article
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18 pages, 5984 KiB  
Article
Magnetic Performance of Eddy Current Suppressing Structures in Additive Manufacturing
by Carsten Klein, Christopher May and Matthias Nienhaus
Actuators 2024, 13(3), 94; https://doi.org/10.3390/act13030094 - 28 Feb 2024
Viewed by 869
Abstract
Additively manufactured soft-magnetic components are inherently bulky leading to significant eddy current losses when applied to electrical machines. Prior works have addressed this issue by implementing structures based on the Hilbert space-filling curve which include eddy current suppressing gaps, thereby reducing the fill [...] Read more.
Additively manufactured soft-magnetic components are inherently bulky leading to significant eddy current losses when applied to electrical machines. Prior works have addressed this issue by implementing structures based on the Hilbert space-filling curve which include eddy current suppressing gaps, thereby reducing the fill factor of the soft-magnetic component. The present research aims at investigating a number of space-filling curves in addition to sheets in order to find the optimal eddy current suppressing structure from an electromagnetic point of view. By means of both analysis and finite-element simulation, it was shown that sheets are superior at minimizing eddy current losses while space-filling curves excel at maximizing the fill factor. Full article
(This article belongs to the Special Issue Electromagnetic Actuators)
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21 pages, 4130 KiB  
Article
Deep Domain Adaptation with Correlation Alignment and Supervised Contrastive Learning for Intelligent Fault Diagnosis in Bearings and Gears of Rotating Machinery
by Bo Zhang, Hai Dong, Hamzah A. A. M. Qaid and Yong Wang
Actuators 2024, 13(3), 93; https://doi.org/10.3390/act13030093 - 27 Feb 2024
Viewed by 853
Abstract
Deep domain adaptation techniques have recently been the subject of much research in machinery fault diagnosis. However, most of the work has been focused on domain alignment, aiming to learn cross-domain features by bridging the gap between source and target domains. Despite the [...] Read more.
Deep domain adaptation techniques have recently been the subject of much research in machinery fault diagnosis. However, most of the work has been focused on domain alignment, aiming to learn cross-domain features by bridging the gap between source and target domains. Despite the success of these methods in achieving domain alignment, they often overlook the class discrepancy present in cross-domain scenarios. This can result in the misclassification of target domain samples that are located near cluster boundaries or far from their associated class centers. To tackle these challenges, a novel approach called deep domain adaptation with correlation alignment and supervised contrastive learning (DCASCL) is proposed, which synchronously realizes both domain distribution alignment and class distribution alignment. Specifically, the correlation alignment loss is used to enforce the model to generate transferable features, facilitating effective domain distribution alignment. Additionally, classifier discrepancy loss and supervised contrastive learning loss are integrated to carry out feature distribution alignment class-wisely. The supervised contrastive learning loss leverages class-specific information of source and target samples, which efficiently promotes the compactness of samples of the same class and the separation of samples from different classes. Moreover, our approach is extensively validated across three diverse datasets, demonstrating its effectiveness in diagnosing machinery faults across different domains. Full article
(This article belongs to the Section Control Systems)
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15 pages, 3516 KiB  
Article
Can Pressure Data from Wearable Insole Devices Be Utilized to Estimate Low Back Moments for Exoskeleton Control System?
by Seungheon Chae, Ahnryul Choi, Jeehae Kang and Joung Hwan Mun
Actuators 2024, 13(3), 92; https://doi.org/10.3390/act13030092 - 27 Feb 2024
Viewed by 907
Abstract
This study presents a machine learning model for predicting lumbar spine moments using data from low-cost sensors, with the ultimate aim of developing a control strategy for waist-active exoskeleton devices. The limitation of sparse features in low-cost insoles was addressed by leveraging a [...] Read more.
This study presents a machine learning model for predicting lumbar spine moments using data from low-cost sensors, with the ultimate aim of developing a control strategy for waist-active exoskeleton devices. The limitation of sparse features in low-cost insoles was addressed by leveraging a source model constructed based on data acquired from the high-precision Pedar-X device, employing a transfer learning technique. The model’s performance saw significant improvement through a training approach that incorporated high-precision commercial insole data and fine-tuning with low-cost insole data. In comparison to the conventional model, this method resulted in a noteworthy 7% enhancement in performance, achieving an rRMSE of approximately 12% and a correlation coefficient of 0.9 in lumbar joint moment prediction. If the model can demonstrate real-time efficacy and effectiveness across various operations in future applications, it holds substantial potential for deployment as an active exoskeleton device for the waist. Full article
(This article belongs to the Section Control Systems)
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15 pages, 3387 KiB  
Article
Hovering Flight of a Robotic Hummingbird: Dynamic Observer and Flight Tests
by Han Wang, Yousef Farid, Liang Wang, Emanuele Garone and André Preumont
Actuators 2024, 13(3), 91; https://doi.org/10.3390/act13030091 - 27 Feb 2024
Viewed by 1006
Abstract
The paper reports on flight tests at hovering of the COLIBRI robot. After a short review of the control model and the stabilization strategy, two different approaches are considered for the attitude reconstruction from the MEMS Inertial Measurement Unit (IMU): the complementary filter [...] Read more.
The paper reports on flight tests at hovering of the COLIBRI robot. After a short review of the control model and the stabilization strategy, two different approaches are considered for the attitude reconstruction from the MEMS Inertial Measurement Unit (IMU): the complementary filter and the full-state dynamic observer, implemented in a specially designed flight control board. It is shown that both strategies provide adequate stabilization at hovering in spite of the strong vibration excitation resulting from the flapping of the wings. Moreover, it is shown that the residual wandering due to noise, robot imperfection, etc., can be significantly reduced by a cascade control loop based on the axial and lateral velocities reconstructed by the full-state observer. Experiments show that this approach based on onboard measurements allows for a station keeping as good as that obtained with velocities reconstructed from an external tracking system. The paper also reports endurance tests conducted with two different robot configurations; the maximum flight time observed is 4 min 30 s. Full article
(This article belongs to the Section Aircraft Actuators)
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17 pages, 3450 KiB  
Article
Development of a Hydraulic Actuator for MRI- and Radiation-Compatible Medical Applications
by Julian Mühlenhoff, Oliver Radler and Thomas Sattel
Actuators 2024, 13(3), 90; https://doi.org/10.3390/act13030090 - 27 Feb 2024
Viewed by 913
Abstract
This paper presents methods for the actuation, measurement, and control of a magnetic resonance imaging- and radiation-compatible single-axis translatory actuation system. As an exemplary demanding use case, the axis is developed for a robotic phantom for evaluating emitted radiation doses of radiotherapy devices. [...] Read more.
This paper presents methods for the actuation, measurement, and control of a magnetic resonance imaging- and radiation-compatible single-axis translatory actuation system. As an exemplary demanding use case, the axis is developed for a robotic phantom for evaluating emitted radiation doses of radiotherapy devices. For this, the robot has to follow given three-dimensional trajectories of patients’ movements with an accuracy of 200 µm. For enabling use of magnetic resonance imaging, actuation of the robot is realized by hydraulic transmission without any metal parts or electrical components at the imaging side. The hydraulic axis is developed, built-up, and tested. In order to compensate for deviations from the targeted actuation trajectory resulting from tolerances, friction, and non-linearities in the system, a combination of photogrammetric measurement and iterative learning control is applied. The developed photogrammetric system is capable of determining the robot’s position with systematic errors of 35 µm and stochastic errors of 0.3 µm. Different types of iterative learning control methods are applied, parameterized, and tested. With this, the hydraulically actuated axis is able to follow given trajectories with maximum errors below 130 µm. Full article
(This article belongs to the Section Actuators for Medical Instruments)
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18 pages, 3859 KiB  
Article
A Novel Cooperative Control Strategy for Three-Degree-of-Freedom Pneumatic Parallel Mechanism
by Qingqing Huang, Guanwei He, Guodong Feng and Beichen Ding
Actuators 2024, 13(3), 89; https://doi.org/10.3390/act13030089 - 26 Feb 2024
Viewed by 999
Abstract
The three-degree-of-freedom (3-DoF) parallel mechanism (PM) is widely used due to its simple structure and ability to avoid coupling problems commonly found in high-DoF PMs. The conventional control approach is usually independent control for each branch of the mechanism using a PID controller, [...] Read more.
The three-degree-of-freedom (3-DoF) parallel mechanism (PM) is widely used due to its simple structure and ability to avoid coupling problems commonly found in high-DoF PMs. The conventional control approach is usually independent control for each branch of the mechanism using a PID controller, without considering the consistency among branches. This paper proposes a novel cooperative control strategy for the 3-DoF PM to achieve both synchronized and differential motion. A pneumatic actuated test rig was constructed to validate the effectiveness of the cooperative controller. The results demonstrate our control approach outperforms the PID controller. Our self-designed platform is functional and intuitive, which can be regarded as a control scheme test bench for a 3-DoF PM. Full article
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11 pages, 1731 KiB  
Article
Reduced-Order Model Approaches for Predicting Airfoil Performance
by Antonio Colanera, Eduardo Di Costanzo, Matteo Chiatto and Luigi de Luca
Actuators 2024, 13(3), 88; https://doi.org/10.3390/act13030088 - 26 Feb 2024
Viewed by 884
Abstract
This study delves into the construction of reduced-order models (ROMs) of a flow field over a NACA 0012 airfoil at a moderate Reynolds number and an angle of attack of 8. Numerical simulations were computed through the finite-volume solver OpenFOAM. The [...] Read more.
This study delves into the construction of reduced-order models (ROMs) of a flow field over a NACA 0012 airfoil at a moderate Reynolds number and an angle of attack of 8. Numerical simulations were computed through the finite-volume solver OpenFOAM. The analysis considers two different reduction techniques: the standard Galerkin projection method, which involves projecting the governing equations onto proper orthogonal decomposition modes (POD−ROMs), and the cluster-based network model (CNM), a fully data-driven nonlinear approach. An analysis of the topology of the dominant POD modes was conducted, uncovering a traveling wave pattern in the wake dynamics. We compared the performances of both ROM techniques regarding their prediction of flow field behavior and integral quantities. The ROM framework facilitates the practical actuation of control strategies with significantly reduced computational demands compared to the full-order approach. Full article
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