Journal Description
Actuators
Actuators
is an international, peer-reviewed, open access journal on the science and technology of actuators and control systems published monthly online by MDPI.
- Open Access— free for readers, with article processing charges (APC) paid by authors or their institutions.
- High Visibility: indexed within Scopus, SCIE (Web of Science), Inspec, and other databases.
- Journal Rank: JCR - Q2 (Engineering, Mechanical) / CiteScore - Q2 (Control and Optimization)
- Rapid Publication: manuscripts are peer-reviewed and a first decision is provided to authors approximately 16.7 days after submission; acceptance to publication is undertaken in 2.5 days (median values for papers published in this journal in the second half of 2023).
- Recognition of Reviewers: reviewers who provide timely, thorough peer-review reports receive vouchers entitling them to a discount on the APC of their next publication in any MDPI journal, in appreciation of the work done.
Impact Factor:
2.6 (2022);
5-Year Impact Factor:
2.6 (2022)
Latest Articles
Parameter Tuning Approach for Incremental Nonlinear Dynamic Inversion-Based Flight Controllers
Actuators 2024, 13(5), 187; https://doi.org/10.3390/act13050187 - 13 May 2024
Abstract
Incremental nonlinear dynamic inversion (INDI) is a widely used approach to controlling UAVs with highly nonlinear dynamics. One key element of INDI-based controllers is the control allocation realizing pseudo controls using available actuators. However, the tracking of commanded pseudo controls is not the
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Incremental nonlinear dynamic inversion (INDI) is a widely used approach to controlling UAVs with highly nonlinear dynamics. One key element of INDI-based controllers is the control allocation realizing pseudo controls using available actuators. However, the tracking of commanded pseudo controls is not the only objective considered during control allocation. Since the approach only works locally due to linearization and the solution is often ambiguous, additional aspects like control efforts or penalizing the deviation of certain states must be considered. Conducting the control allocation by solving a quadratic program this results in a considerable number of weighting parameters, which must be tuned during control design. Currently, this is conducted manually and is therefore time consuming. An automated approach for tuning these parameters is therefore highly beneficial. Thus, this paper presents and evaluates a model-based approach automatically tuning the control allocation parameters of a tiltrotor VTOL using an optimization algorithm. This optimization algorithm searches for optimal parameters minimizing a cost functional that reflects the design target. This cost functional is calculated based on a test mission for the VTOL which is conducted within a simulation environment. The test mission represents the common operating range of the VTOL. The simulation environment consists of an aircraft model as well as a model of the INDI-based controller which is dependent on the control allocation parameters. On this basis, model-based optimization is conducted and the optimal parameters are identified. Finally, successful real-world tests on a 4-degrees-of-freedom testbench using the identified parameters are presented. Since the control allocation parameters can significantly influence the aircraft’s stability, the 4-DOF testbench for the aircraft is required for rapid validation of the parameters at a minimum amount of risk.
Full article
(This article belongs to the Special Issue Flight Control Systems and Dynamic Simulation for Aerospace Applications)
Open AccessArticle
Effect of Structural Parameters on Output Characteristics of a Novel Self-Supplied Aviation Intelligent Pump
by
Xudong Han, Yongling Fu, Yan Wang, Feixiang Yan and Liming Yu
Actuators 2024, 13(5), 186; https://doi.org/10.3390/act13050186 (registering DOI) - 13 May 2024
Abstract
The aviation intelligent pump system is an effective solution to aircraft hydraulic systems’ inefficient power consumption and temperature increase. A self-supplied aviation intelligent pump (SAIP) has a high power-to-weight ratio and compact structure, making it the optimal choice for an intelligent pump. To
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The aviation intelligent pump system is an effective solution to aircraft hydraulic systems’ inefficient power consumption and temperature increase. A self-supplied aviation intelligent pump (SAIP) has a high power-to-weight ratio and compact structure, making it the optimal choice for an intelligent pump. To analyze the output characteristics of a novel aviation intelligent pump, it is crucial to establish an accurate mathematical model that describes its dynamic characteristics. This can be achieved by analyzing the working principle and exploring the influence of critical parameters. The paper introduces the composition and working principle of a self-supplied electro-hydraulic servo variable displacement pump. It then establishes a mathematical model of the whole pump, with a detailed analysis and modeling of the critical variable mechanism and the swash plate assembly’s load moment. A simulation model was created to examine the impact of crucial structural parameters, such as the offset spring’s stiffness and control piston’s diameter, on the output characteristics of the intelligent pump. An experimental platform was also constructed, and the experimental results confirm the accuracy of the SAIP model presented in this paper. The investigation of the output characteristics fully reveals the dynamic performance of the SAIP. This provides the basis for the subsequent design of high-performance flow and pressure control strategies and aids in researching intelligent aircraft hydraulic systems.
Full article
(This article belongs to the Special Issue Flight Control Systems and Dynamic Simulation for Aerospace Applications)
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Open AccessArticle
Overvoltage Avoidance Control Strategy for Braking Process of Brushless DC Motor Drives with Small DC-Link Capacitance
by
Wei Chen, Jialong Wu, Xinmin Li and Chen Li
Actuators 2024, 13(5), 185; https://doi.org/10.3390/act13050185 - 13 May 2024
Abstract
Single-phase input rectifier brushless DC motor drives with a small film capacitor have many advantages, such as high power density and high reliability. However, when the motor system operates in regenerative braking mode, the dc-link capacitor with reduced capacitance may suffer from overvoltage
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Single-phase input rectifier brushless DC motor drives with a small film capacitor have many advantages, such as high power density and high reliability. However, when the motor system operates in regenerative braking mode, the dc-link capacitor with reduced capacitance may suffer from overvoltage without adding additional hardware circuits. At the same time, the braking torque control of the motor will be affected by speed variations. In order to ensure smooth and reliable operation of the motor system, an anti-overvoltage braking torque control method is proposed in this article. The relationship among the dc-link capacitance, the dc-link capacitor voltage, and the speed during regenerative braking is analyzed quantitatively, and the speed at which the regenerative braking is switched to the plug braking is obtained, which in turn consumes the capacitor energy to avoid dc-link overvoltage. Additionally, based on the relationship between the controllability of the braking torque and the speed, a reference value of the braking current that matches the speed is designed. The proposed method makes use of the capacitor’s energy storage during regenerative braking. Meanwhile, it mitigates the impact of motor speed on braking torque. Finally, the effectiveness of the proposed method is verified on a motor platform equipped with the dc-link film capacitor.
Full article
(This article belongs to the Special Issue Power Electronics and Actuators)
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Open AccessArticle
Electromagnetic Torque Components Analysis of Ultra-High-Speed Permanent-Magnet Synchronous Motor for Fuel Cell Air Compressor
by
Jiaming Zhou, Jinming Zhang, Fengyan Yi, Donghai Hu, Caizhi Zhang, Yanzhao Li, Zhiming Zhang, Guangping Wu and Jinxiang Song
Actuators 2024, 13(5), 184; https://doi.org/10.3390/act13050184 - 12 May 2024
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The ultra-high-speed electric air compressor (UHSEAC) is affected by the electromagnetic torque components of the ultra-high-speed permanent magnet synchronous motor (UHSPMSM) during wide-range speed regulation, resulting in intense speed fluctuation. Electromagnetic torque components are generated by the effects of permanent magnet field harmonics,
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The ultra-high-speed electric air compressor (UHSEAC) is affected by the electromagnetic torque components of the ultra-high-speed permanent magnet synchronous motor (UHSPMSM) during wide-range speed regulation, resulting in intense speed fluctuation. Electromagnetic torque components are generated by the effects of permanent magnet field harmonics, stator slotting, and current harmonics. It is very important to conduct simulation comparisons and theoretical descriptions of different sources of pulsation factors. In this paper, firstly, the electromagnetic torque model of UHSPMSM with a rated speed of 80,000 rpm is constructed and verified by an experimental bench. Secondly, the electromagnetic torque components of UHSPMSM are extracted on the basis of the electromagnetic torque model. Finally, the electromagnetic torque components’ characteristic law is investigated under different ultra-high-speed operating conditions. The results show that under ultra-high-speed operation, the frequency and amplitude of electromagnetic torque components become larger with increasing speed. And the amplitude of electromagnetic torque components becomes larger with increasing torque. This paper constructs the observation object of the high-frequency state observer and does the preliminaries for the design of the UHSEAC controller.
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Open AccessArticle
The Effect of Arm Movements on the Dynamics of the Wheelchair Frame during Manual Wheelchair Actuation and Propulsion
by
Franz Konstantin Fuss, Adin Ming Tan and Yehuda Weizman
Actuators 2024, 13(5), 183; https://doi.org/10.3390/act13050183 - 11 May 2024
Abstract
Wheelchair propulsion and actuation are influenced by the moving masses of the wheelchair user; however, the extent of this effect is still unclear. The main evidence of this effect is that the speed of the wheelchair frame continues to increase after the end
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Wheelchair propulsion and actuation are influenced by the moving masses of the wheelchair user; however, the extent of this effect is still unclear. The main evidence of this effect is that the speed of the wheelchair frame continues to increase after the end of the push phase. The wheelchair’s speed was measured using IMUs and the duration of the push period was recorded using miniaturised pressure sensors attached to the driver’s middle fingers. The velocity and acceleration were determined for various average stroke cycle speeds to determine the speed dependency of the acceleration. The wheelchair was then mounted on a force plate to measure the inertial forces of the hands moving back and forth. The aerodynamic drag and rolling resistance forces were determined from coast-down experiments. Based on the measured forces, the behaviour of the force and velocity profiles was finally modelled by gradually reducing the mass of the arms and thus their inertial force. The results showed that the wheelchair is accelerated throughout the push phase (except for a temporary deceleration in the middle of the push phase at higher velocities), and that this acceleration continues well after the push phase. In the second half of the recovery phase, the wheelchair decelerates. The horizontal inertial forces measured on the force plate are predominantly negative in the push phase and in the second half of the recovery phase, and positive in the first half of the push phase, and their impulse is zero due to the conservation of momentum. Modelling the wheelchair with moving masses showed that reducing the horizontal inertial forces has no effect on the driver’s propulsive force but reduces the velocity fluctuations. The main conclusion of this research is that the wheelchair user’s power should be calculated only from the pure propulsive force that is required in the push phase to overcome the dissipative forces and that enables the gain or loss in speed per stroke cycle, but not directly from the measured velocity.
Full article
(This article belongs to the Section Actuators for Robotics)
Open AccessArticle
Study of Self-Excited Thermomechanical Oscillator with Shape Memory Alloys
by
Ivo Yotov, Georgi Todorov and Todor Todorov
Actuators 2024, 13(5), 182; https://doi.org/10.3390/act13050182 - 11 May 2024
Abstract
In this paper, a new type of self-excited thermomechanical oscillator containing an oscillating shape memory alloy (SMA) filament with two symmetrically arranged spheres is investigated. The self-excitation of the oscillations is due to a heater of constant temperature, which causes periodic contractions of
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In this paper, a new type of self-excited thermomechanical oscillator containing an oscillating shape memory alloy (SMA) filament with two symmetrically arranged spheres is investigated. The self-excitation of the oscillations is due to a heater of constant temperature, which causes periodic contractions of the filament when it approaches it. The contracted filament moves away from the heater a distance sufficient to cool it. Under the action of the weight of the spheres, the cooled filament re-approaches the heater, causing the above processes to repeat periodically. On the basis of experimental studies, approximating functions of the heater’s heat field distribution are derived. A dynamic model of the oscillator has been created, in which the minor and major hysteresis in the SMA alloy and the distribution of the heat field around the heater have been taken into account. Through numerical solutions of the differential equations, the laws of motion of the spheres are obtained. The displacements of the spheres in two perpendicular directions were measured using an experimental system. The obtained experimental results validate the proposed dynamic model and its assumptions with a high degree of confidence. Conclusions are drawn about the stochastic nature of the oscillations due to the hysteresis properties of the SMA and the temperature variation of the natural frequency of the oscillating system.
Full article
(This article belongs to the Special Issue Shape Memory Alloy (SMA) Actuators and Their Applications)
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Open AccessArticle
A Framework for IBVS Using Virtual Work
by
Qiuda Yu, Wu Wei, Dongliang Wang, Yanjie Li and Yong Gao
Actuators 2024, 13(5), 181; https://doi.org/10.3390/act13050181 - 10 May 2024
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The visual servoing of manipulators is challenged by two main problems: the singularity of the inverse Jacobian and the physical constraints of a manipulator. In order to overcome the singularity issue, this paper presents a novel approach for image-based visual servoing (IBVS), which
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The visual servoing of manipulators is challenged by two main problems: the singularity of the inverse Jacobian and the physical constraints of a manipulator. In order to overcome the singularity issue, this paper presents a novel approach for image-based visual servoing (IBVS), which converts the propagation of errors in the image plane into the conduction of virtual forces using the principle of virtual work. This approach eliminates the need for Jacobian inversion computations and prevents matrix inversion singularity. To tackle physical constraints, reverse thinking is adopted to derive the function of the upper and lower bounds of the joint velocity on the joint angle. This enables the proposed method to configure the physical constraints of the robot in a more intuitive manner. To validate the effectiveness of the proposed method, an eye-in-hand system based on UR5 in VREP, as well as a physical robot, were established.
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Open AccessArticle
Pneumatically Actuated Soft Robotic Hand and Wrist Exoskeleton for Motion Assistance in Rehabilitation
by
Tanguy Ridremont, Inderjeet Singh, Baptiste Bruzek, Alexandra Jamieson, Yixin Gu, Rochdi Merzouki and Muthu B. J. Wijesundara
Actuators 2024, 13(5), 180; https://doi.org/10.3390/act13050180 - 10 May 2024
Abstract
Exoskeletons are being explored for assisting motion therapy for neurological impairment-related rehabilitation. Soft robotic exoskeletons are gaining more attention for upper-extremity applications due to their simplistic actuation mechanisms and compliant nature. To regain fine motor hand functions, it is desired to have both
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Exoskeletons are being explored for assisting motion therapy for neurological impairment-related rehabilitation. Soft robotic exoskeletons are gaining more attention for upper-extremity applications due to their simplistic actuation mechanisms and compliant nature. To regain fine motor hand functions, it is desired to have both hand and wrist motions in a coordinated fashion, as most daily living tasks require a combination of both hand and wrist joint motions. However, a soft robotic exoskeleton with hand and wrist motion together is an underdeveloped area. This paper presents a pneumatically actuated soft robotic exoskeleton designed to provide coordinated assistive motion to the hand and wrist joints using PD-based feedback control. The results showed the potential of the exoskeleton to provide flexion/extension rehabilitation exercises and task-oriented rehabilitation practices. Additionally, the results have confirmed that the implemented PD control ensures that the exoskeleton reaches the targeted angular trajectories and velocities. Two modes, full and partial assistance, were successfully tested to verify the ability of the exoskeleton to accommodate varying levels of impairment.
Full article
(This article belongs to the Special Issue Soft Actuators for Medical Robotics)
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Open AccessArticle
Practical Comparison of Two- and Three-Phase Bearingless Permanent Magnet Slice Motors for Blood Pumps
by
Jonathan E. M. Lawley, Giselle C. Matlis, Amy L. Throckmorton and Steven W. Day
Actuators 2024, 13(5), 179; https://doi.org/10.3390/act13050179 - 8 May 2024
Abstract
The majority of bearingless permanent magnet slice motors (BPMSMs) used in commercially available rotary blood pumps use a two-phase configuration, but it is unclear as to whether or not a comparable three-phase configuration would offer a better performance. This study compares the performance
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The majority of bearingless permanent magnet slice motors (BPMSMs) used in commercially available rotary blood pumps use a two-phase configuration, but it is unclear as to whether or not a comparable three-phase configuration would offer a better performance. This study compares the performance of two-phase and three-phase BPMSM configurations. Initially, two nominal designs were manufactured and empirically tested for their performance characteristics, namely, the axial stiffness, radial stiffness, and current force. Subsequently, finite element analysis (FEA) models were developed based on these nominal devices and validated against the empirical results. Simulations were then employed to assess the sensitivity of performance characteristics to variations in seven different geometric features of the models for both configurations. Our findings indicate that the nominal three-phase design had a higher axial stiffness and radial stiffness, but resulted in a lower axial-to-radial-stiffness ratio when compared to the nominal two-phase design. Additionally, while the nominal two-phase design shows a higher current force, the nominal three-phase design proves to be slightly superior when the force generated is considered relative to the power usage. Notably, the three-phase configuration demonstrates a greater sensitivity to dimensional changes in the geometric features. We observed that alterations in the air gap and rotor length lead to the most significant variations in performance characteristics. Although most changes in specific geometric features entail equal tradeoffs, increasing the head protrusion positively influences the overall performance. Moreover, we illustrated the interdependent nature of the head height and rotor height on the performance characteristics. Overall, this study delineates the strengths and weaknesses of each configuration, while also providing general insights into the relationship between specific geometric features and performance characteristics of BPMSMs.
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(This article belongs to the Special Issue Power Electronics and Actuators)
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Open AccessArticle
Cellulose-Based Triboelectric Nanogenerator Prepared by Multi-Fluid Electrospinning for Respiratory Protection and Self-Powered Sensing
by
Jiaqi Huang, Yan Zhang, Haijiao Yu, Guangping Han and Wanli Cheng
Actuators 2024, 13(5), 178; https://doi.org/10.3390/act13050178 - 8 May 2024
Abstract
A cellulose-based triboelectric nanogenerator (TENG) with fiber–wave–arch structure was prepared through a multi-fluid electrospinning process for air filtration and wind sensing. The TENG is composed of a cellulose nanocrystals (CNC)/zein membrane and a cyanoethyl cellulose (CEC)/polyvinylidene fluoride (PVDF) membrane. The results show that
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A cellulose-based triboelectric nanogenerator (TENG) with fiber–wave–arch structure was prepared through a multi-fluid electrospinning process for air filtration and wind sensing. The TENG is composed of a cellulose nanocrystals (CNC)/zein membrane and a cyanoethyl cellulose (CEC)/polyvinylidene fluoride (PVDF) membrane. The results show that the addition of CEC improves the output performance and filterability of TENG. At the same time, the reduced diameter and high roughness of CEC/PVDF nanofibers improve the output performance of the TENG. The TENG with a 6 wt% CEC/PVDF solution concentration has the highest output performance with a short-circuit current of 3.30 μA and an open-circuit voltage of 10.01 V. The particle filtration of 12 wt% CEC/PVDF TENG is the best, showing an efficiency of 98.84% and a pressure drop of 50 Pa. The TENG also has a good formaldehyde filtration capability with an efficiency of 92% at 0.25 mg/m3. The TENG shows great potential in self-powered sensor applications.
Full article
(This article belongs to the Section Actuator Materials)
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Open AccessArticle
Structural Optimization Study on a Three-Degree-of-Freedom Piezoelectric Ultrasonic Transducer
by
Zhizhong Wu, Zhao Zhang, Deguang Wu, Yuanhang Chen, Fan Hu, Chenxin Guo and Lijun Tang
Actuators 2024, 13(5), 177; https://doi.org/10.3390/act13050177 - 8 May 2024
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A three-degree-of-freedom (3-DOF) piezoelectric ultrasonic transducer is a critical component in elliptical and longitudinal ultrasonic vibration-assisted cutting processes, with its geometric structure directly influencing its performance. This paper proposes a structural optimization method based on a convolutional neural network (CNN) and non-dominated sorting
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A three-degree-of-freedom (3-DOF) piezoelectric ultrasonic transducer is a critical component in elliptical and longitudinal ultrasonic vibration-assisted cutting processes, with its geometric structure directly influencing its performance. This paper proposes a structural optimization method based on a convolutional neural network (CNN) and non-dominated sorting genetic algorithm II (NSGA2). This method establishes a transducer lumped model to obtain the electromechanical coupling coefficients (X- and Z- ) and thermal power (X-P) indicators, evaluating the bending and longitudinal vibration performance of the transducer. By creating a finite element model of the transducer with mechanical losses, a dataset of different transducer performance parameters, including the tail mass, piezoelectric stack, and dimensions of the horn, is obtained. Training a CNN model with this dataset yields objective functions for the relationship between different transducer geometric structures and performance parameters. The NSGA2 algorithm solves the X- and Z- objective functions, obtaining the Pareto set of the transducer geometric dimensions and determining the optimal transducer geometry in conjunction with X-P. This method achieves simultaneous improvements in X- and Z- of the transducer by 22.33% and 25.89% post-optimization and reduces X-P to 18.97 W. Furthermore, the finite element simulation experiments of the transducer validate the effectiveness of this method.
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Open AccessArticle
Trajectory Planning through Model Inversion of an Underactuated Spatial Gantry Crane Moving in Structured Cluttered Environments
by
Jason Bettega, Dario Richiedei and Iacopo Tamellin
Actuators 2024, 13(5), 176; https://doi.org/10.3390/act13050176 - 7 May 2024
Abstract
Handling suspended loads in cluttered environments is critical due to the oscillations arising while the load is traveling. Exploiting active control algorithms is often unviable in industrial applications, due to the necessity of installing sensors on the load side, which is expensive and
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Handling suspended loads in cluttered environments is critical due to the oscillations arising while the load is traveling. Exploiting active control algorithms is often unviable in industrial applications, due to the necessity of installing sensors on the load side, which is expensive and often impractical due to technological limitations. In this light, this paper proposes a trajectory planning method for underactuated, non-flat, non-minimum phase spatial gantry crane moving in structured cluttered environments. The method relies on model inversion. First, the system dynamics is partitioned into actuated and unactuated coordinates and then the load displacements are described as a non-linear separable function of these. The unactuated dynamic is unstable; hence, the displacement, velocity, and acceleration references are modified through the output redefinition technique. Finally, platform trajectory is computed, and the desired displacements of the load are obtained. The effectiveness of the proposed method is assessed through numerical and experimental tests performed on a laboratory testbed composed by an Adept Quattro robot moving a pendulum. The load is moved in a cluttered environment, and collisions are avoided while simultaneously tracking the prescribed trajectory effectively.
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(This article belongs to the Special Issue Dynamics and Control of Underactuated Systems)
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Identification Algorithm for Stability Improvement of Welding Robot End-Effector
by
Lijian Liu, Yongkang Zhang, Bin Wei and Guang Yang
Actuators 2024, 13(5), 175; https://doi.org/10.3390/act13050175 - 6 May 2024
Abstract
Aiming to solve the problem that the significant error between the actual joint torque and the calculated joint torque of a welding robot leads to the vibration of the end-effector, which in turn affects the stability of the end-effector, this paper proposes a
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Aiming to solve the problem that the significant error between the actual joint torque and the calculated joint torque of a welding robot leads to the vibration of the end-effector, which in turn affects the stability of the end-effector, this paper proposes a identification algorithm based on the Weighted Least Squares Genetic Algorithm (WLS-GA) to construct and solve the dynamical model to obtain the accurate dynamical parameters. Firstly, a linear model of welding robot dynamics is derived. The fifth-order optimal Fourier series excitation trajectory is designed to collect experimental data such as joint torque. Then, a rough solution of the parameters to be recognized is obtained by solving the dynamics model through the Weighted Least Squares (WLS) method, the search space is determined based on the rough solution, and the optimal solution is obtained by using the Genetic Algorithm (GA) to perform a quadratic search in the search space. Finally, the identification data obtained from the algorithm is analyzed and compared with the experimental data. The results show that the error between the identification data obtained using the WLS-GA identification algorithm and the experimental data is relatively small. The results show that the identification data obtained using the WLS-GA identification algorithm have less error than the experimental data, taking the Root Mean Square (RMS) value of the joint torque error obtained using the weighted least squares algorithm as a criterion. The accuracy of the WLS-GA identification algorithm can be improved by up to 66.85% compared with that of the weighted least squares algorithm and by up to 78.0% compared with that of the Ordinary Least Squares (OLS) algorithm. In summary, the WLS-GA identification algorithm can accurately identify the dynamic parameters of the welding robot and more accurately construct a dynamic model to solve the effect of joint torque error on the control characteristics of the welding robot. It can improve the stability of the end-effector of the welding robot to ensure the quality of the automobile body and beam welding and welding speed.
Full article
(This article belongs to the Special Issue Design and Application of Actuators with Multi-DOF Movement-2nd Edition)
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Open AccessArticle
Improvement in the Accuracy and Efficiency of Smoothed Particle Hydrodynamics: Point Generation and Adaptive Particle Refinement/Coarsening Algorithms
by
Jun Zhang, Yanchao Ding, Wei Wu, Wenjie Li, Zhaoming Zhang and Yanmei Jiao
Actuators 2024, 13(5), 174; https://doi.org/10.3390/act13050174 - 5 May 2024
Abstract
An adaptive particle refinement (APR) algorithm has been developed for the smoothed particle hydrodynamics (SPH) method to augment the resolution of the region of interest to achieve high accuracy and simultaneously reduce the cost of computational resources. It is widely applied in the
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An adaptive particle refinement (APR) algorithm has been developed for the smoothed particle hydrodynamics (SPH) method to augment the resolution of the region of interest to achieve high accuracy and simultaneously reduce the cost of computational resources. It is widely applied in the field of fluid-controlling problems involving large interface deformations, such as the two-phase flow and fluid–structure interaction because this algorithm can capture the interface with high accuracy. Nonetheless, existing APR algorithms widely encounter computational dispersion issues at the interface of regions of different particle resolutions. Moreover, traditional shifting algorithms applied in the APR processes also have difficulties in dealing with particles with different smooth lengths. In this work, an algorithm for fast particle generation was first developed based on the accelerated ray method, which accelerates the discretization of the flow field into particles. Then, a dynamic refinement/coarsening algorithm based on the APR algorithm is proposed to solve the computational dispersion problem that occurs at the refinement/coarsening interfaces. In addition, the shifting algorithm was improved in this work to ensure the particles are always well distributed during numerical calculations and, thus, can efficiently facilitate the adaptive particle refinement/coarsening processes. Comparative analysis indicates that the robust algorithms developed for the SPH method in this work can lead to more precise and reasonable flow fields compared with the conventional SPH adaptive methods.
Full article
(This article belongs to the Special Issue Active Flow Control: Recent Advances in Fundamentals and Applications — Volume II)
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Unified Sufficient Conditions for Predefined-Time Stability of Non-Linear Systems and Its Standard Controller Design
by
Bing Xiao, Haichao Zhang, Shijie Zhao, Zhaoyue Chen and Lu Cao
Actuators 2024, 13(5), 173; https://doi.org/10.3390/act13050173 - 5 May 2024
Abstract
This paper presents a unified Lyapunov-based predefined-time stability theorem that includes three sufficient conditions. The standard theoretical analysis method for achieving predefined-time stability of non-linear systems using this theorem is provided within the framework of Lyapunov theory. The developed Lyapunov-based theorem facilitates the
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This paper presents a unified Lyapunov-based predefined-time stability theorem that includes three sufficient conditions. The standard theoretical analysis method for achieving predefined-time stability of non-linear systems using this theorem is provided within the framework of Lyapunov theory. The developed Lyapunov-based theorem facilitates the establishment of equivalence between the existing Lyapunov theorems concerning predefined-time stability. Furthermore, when the presented sufficient conditions are relaxed, the predefined-time stability conclusion for non-linear systems degenerates into a finite-time one. Consequently, a standard non-singular sliding mode control framework based on the unified Lyapunov-based theorem is developed for a Lagrangian system to ensure its predefined-time stability. Exemplary numerical simulation results are subsequently given, in order to illustrate the convergence behavior of the system states and confirm that the controlled systems are predefined-time stable.
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(This article belongs to the Section Control Systems)
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Design and Implementation of an
by
Deepanshu Bagati, Toufik Souanef and James F. Whidborne
Actuators 2024, 13(5), 172; https://doi.org/10.3390/act13050172 - 2 May 2024
Abstract
A new approach for output feedback adaptive control based on a proportional adaptation law is presented. The effectiveness of this design is assessed in simulation and validated through real-time testing on an airfoil pitch control wind tunnel experimental rig. Experimental evaluation
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A new approach for output feedback adaptive control based on a proportional adaptation law is presented. The effectiveness of this design is assessed in simulation and validated through real-time testing on an airfoil pitch control wind tunnel experimental rig. Experimental evaluation of the robustness of the controllers, assessed by introducing various disturbances into the control signals, shows that the adaptive control has a better performance compared to PID control, particularly in scenarios with reduced control effectiveness and time-varying disturbances. The experimental results demonstrate the efficacy of the proposed method in practical applications.
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(This article belongs to the Section Aircraft Actuators)
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Bidirectional Multi-Spectral Vibration Control: Insights from Automotive Engine Mounting Systems in Two-Dimensional Structures with a Damaged Vertical Active Element
by
Dongwoo Hong, Hojoon Moon and Byeongil Kim
Actuators 2024, 13(5), 171; https://doi.org/10.3390/act13050171 - 1 May 2024
Abstract
Active mounting systems have become more prevalent in recent years to effectively mitigate structure-induced vibration across the automobile chassis. This trend is particularly evident in engine mounts. Considerable research has been dedicated to this approach owing to its potential to enhance the quietness
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Active mounting systems have become more prevalent in recent years to effectively mitigate structure-induced vibration across the automobile chassis. This trend is particularly evident in engine mounts. Considerable research has been dedicated to this approach owing to its potential to enhance the quietness and travel comfort of automobiles. However, prior research has concentrated on a limited spectrum of specific vibrations and noise control or has been restricted to vertical vibration control. This article describes the modeling, analysis, and control of a source structure employing a multidirectional active mounting system designed to closely simulate the position and direction of an actual automobile engine mount. A piezoelectric stack actuator is connected in series to an elastic (rubber) mount to form an active mount. The calculation of the secondary force required for each active mount is achieved through the application of harmonic excitation forces. The control signal can also reduce vibrations caused by destructive interference with the input signal. Furthermore, horizontal oscillations can be mitigated by manipulating the parameters via dynamic interconnections of the source structure. We specifically examined the level of vibration reduction performance in the absence of a vertical active element operation and determined whether the control is feasible. Simulation outcomes demonstrate that this active mount, which operates in both the vertical and horizontal directions, effectively mitigates excitation vibrations. Furthermore, a simulation was conducted to mitigate the vibrations caused by complex signals (AM and FM signals) and noise. This was achieved by monitoring the system response using an adaptive filter NLMS algorithm. Adaptive filter simulations demonstrate that the control efficacy degrades in response to complex signals and noise, although the overall relaxation trend remains unchanged.
Full article
(This article belongs to the Special Issue Actuators and Dampers for Vibration Control: Damping and Isolation Applications - Volume II)
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Adaptive Nonsingular Fast Terminal Sliding Mode-Based Direct Yaw Moment Control for DDEV under Emergency Conditions
by
Yixi Zhang, Jian Ma and Yang Zhou
Actuators 2024, 13(5), 170; https://doi.org/10.3390/act13050170 - 1 May 2024
Abstract
This paper presents an innovative three-level direct yaw moment control strategy for distributed drive electric vehicles (DDEV) under emergency conditions. The phase plane analysis is used at the supervisory level to design the stability boundary function taking into account the impact of the
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This paper presents an innovative three-level direct yaw moment control strategy for distributed drive electric vehicles (DDEV) under emergency conditions. The phase plane analysis is used at the supervisory level to design the stability boundary function taking into account the impact of the road adhesion coefficient. To guarantee the performance of finite-time convergence and singularity-free methods, the adaptive nonsingular fast terminal sliding mode control (ANFTSMC) is developed at the decision level to determine the extra yaw moment for tracking the intended side slip angle and yaw rate. Among this, the unstable domain in the phase plane is further separated into moderately and severely unstable according to the degree of vehicle instability, which is defined by the distance between the state phase point and the stability boundary. Meanwhile, the adaptive weight between the handling and stability is obtained. At the executive level, the quadratic programming algorithm is adopted to allocate four-wheel torque with the objective of optimal tire utilization rate. Finally, the co-simulation test is executed in both closed-loop and open-loop circumstances; according to the simulation results, the presented ANFTSMC method outperforms the SMC, and it can decrease the tracking error and improve the handling and stability.
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(This article belongs to the Section Actuators for Land Transport)
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Open AccessArticle
A Novel Extended Unscented Kalman Filter Is Designed Using the Higher-Order Statistical Property of the Approximate Error of the System Model
by
Chengyi Li and Chenglin Wen
Actuators 2024, 13(5), 169; https://doi.org/10.3390/act13050169 - 1 May 2024
Abstract
In the actual working environment, most equipment models present nonlinear characteristics. For nonlinear system filtering, filtering methods such as the Extended Kalman Filter (EKF), Unscented Kalman Filter (UKF), and Cubature Kalman Filter (CKF) have been developed successively, all of which show good results.
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In the actual working environment, most equipment models present nonlinear characteristics. For nonlinear system filtering, filtering methods such as the Extended Kalman Filter (EKF), Unscented Kalman Filter (UKF), and Cubature Kalman Filter (CKF) have been developed successively, all of which show good results. However, in the process of nonlinear system filtering, the performance of EKF decreases with an increase in the truncation error and even diverges. With improvement of the system dimension, the sampling points of UKF are relatively few and unrepresentative. In this paper, a novel high-order extended Unscented Kalman Filter (HUKF) based on an Unscented Kalman Filter is designed using the higher-order statistical properties of the approximate error. In addition, a method for calculating the approximate error of the multi-level approximation of the original function under the condition that the measurement is not rank-satisfied is proposed. The effectiveness of the filter is verified using digital simulation experiments.
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(This article belongs to the Special Issue From Theory to Practice: Incremental Nonlinear Control)
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Open AccessArticle
Sensor-Based Identification of Singularities in Parallel Manipulators
by
Jose L. Pulloquinga, Marco Ceccarelli, Vicente Mata and Angel Valera
Actuators 2024, 13(5), 168; https://doi.org/10.3390/act13050168 - 1 May 2024
Abstract
Singularities are configurations where the number of degrees of freedom of a robot changes instantaneously. In parallel manipulators, a singularity could reduce the mobility of the end-effector or produce uncontrolled motions of the mobile platform. Thus, a singularity is a critical problem for
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Singularities are configurations where the number of degrees of freedom of a robot changes instantaneously. In parallel manipulators, a singularity could reduce the mobility of the end-effector or produce uncontrolled motions of the mobile platform. Thus, a singularity is a critical problem for mechanical design and model-based control. This paper presents a general sensor-based method to identify singularities in the workspace of parallel manipulators with low computational cost. The proposed experimental method identifies a singularity by measuring sudden changes in the end-effector movements and huge increments in the forces applied by the actuators. This paper uses an inertial measurement unit and a 3D tracking system for measuring the end-effector movements, and current sensors for the forces exerted by the actuators. The proposed sensor-based identification of singularities is adjusted and implemented in three different robots to validate its effectiveness and feasibility for identifying singularities. The case studies are two prototypes for educational purposes—a five-bar mechanism and an L-CaPaMan parallel robot—and a four-degree-of-freedom robot for rehabilitation purposes. The tests showcase its potential as a practical solution for singularity identification in educational and industrial robots.
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(This article belongs to the Special Issue Advanced Robots: Design, Control and Application—2nd Edition)
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