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Reconfigurable Slip Vectoring Control in Four In-Wheel Drive Electric Vehicles -
Use the Force: Review of High-Rate Actuation of Shape Memory Alloys -
Design and Evaluation of Fault-Tolerant Electro-mechanical Actuators for Flight Controls of Unmanned Aerial Vehicles -
Optimized Voltage-Induced Control of Magnetic Domain-Wall Propagation in Hybrid Piezoelectric/Magnetostrictive Devices
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 many other databases.
- Journal Rank: CiteScore - Q2 (Control and Optimization)
- Rapid Publication: manuscripts are peer-reviewed and a first decision provided to authors approximately 14.4 days after submission; acceptance to publication is undertaken in 2.9 days (median values for papers published in this journal in the first half of 2021).
- 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:
1.994 (2020)
;
5-Year Impact Factor:
2.623 (2020)
Latest Articles
Design and Implementation of a Robotic Hip Exoskeleton for Gait Rehabilitation
Actuators 2021, 10(9), 212; https://doi.org/10.3390/act10090212 - 29 Aug 2021
Abstract
In this paper, a four degrees-of-freedom robotic hip exoskeleton was proposed for gait rehabilitation. The robotic hip exoskeleton was designed with active flexion/extension and passive abduction/adduction at each hip joint to comply with the movement of the thigh. Due to each user’s different
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In this paper, a four degrees-of-freedom robotic hip exoskeleton was proposed for gait rehabilitation. The robotic hip exoskeleton was designed with active flexion/extension and passive abduction/adduction at each hip joint to comply with the movement of the thigh. Due to each user’s different lower limbs characteristics and unknown torques at hip joints, model-free linear extended state observer (LESO)-based controllers were proposed for rehabilitation gait control. The prototypes of the robotic hip exoskeleton and controller designs were validated and compared through walking and ascending rehabilitation experiments. Additionally, a motion captured system and EMG signals were used to investigate the walking assistance of the robotic hip exoskeleton.
Full article
(This article belongs to the Special Issue Actuators in Robotic Control)
Open AccessArticle
A Twisted String, Flexure Hinges Approach for Design of a Wearable Haptic Thimble
Actuators 2021, 10(9), 211; https://doi.org/10.3390/act10090211 - 29 Aug 2021
Abstract
Wearable haptic devices in the shape of actuated thimbles are used to render the sense of touch in teleoperation and virtual reality scenarios. The design of similar devices has to comply with concurring requirements and constraints: lightweight and compactness, intensity and bandwidth of
[...] Read more.
Wearable haptic devices in the shape of actuated thimbles are used to render the sense of touch in teleoperation and virtual reality scenarios. The design of similar devices has to comply with concurring requirements and constraints: lightweight and compactness, intensity and bandwidth of the rendered signals. Micro-sized motors require a mechanical reduction to increase the output force, at the cost of noise and vibrations introduced by conventional gear reducers. Here we propose a different actuation method, based on a miniaturized twisted string actuator and a flexure hinge transmission mechanism. The latter is required to transmit and transform the pulling force of the twist actuator to a pushing force of the plate in contact with the fingerpad. It achieves a lightweight and noiseless actuation in a compact mechanism. In this work, we present design guidelines of the proposed approach, optimization, and FEM analysis of the flexure hinge mechanism, implementation of the prototype, and experimental characterization of the twist actuator measuring frequency response and output force capabilities.
Full article
(This article belongs to the Special Issue Actuators for Haptics)
Open AccessArticle
Human–Machine Cooperative Control of Intelligent Vehicles for Lane Keeping—Considering Safety of the Intended Func-tionality
Actuators 2021, 10(9), 210; https://doi.org/10.3390/act10090210 - 28 Aug 2021
Abstract
Reasonably foreseeable misuse by persons, as a primary aspect of safety of the intended functionality (SOTIF), has a significant effect on cooperation performance for lane keeping. This paper presents a novel human–machine cooperative control scheme with consideration of SOTIF issues caused by driver
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Reasonably foreseeable misuse by persons, as a primary aspect of safety of the intended functionality (SOTIF), has a significant effect on cooperation performance for lane keeping. This paper presents a novel human–machine cooperative control scheme with consideration of SOTIF issues caused by driver error. It is challenging to balance lane keeping performance and driving freedom when driver error occurs. A safety evaluation strategy is proposed for safety supervision, containing assessments of driver error and lane departure risk caused by driver error. A dynamic evaluation model of driver error is designed based on a typical driver model in the loop to deal with the uncertainty and variability of driver behavior. Additionally, an extension model is established for determining the cooperation domain. Then, an authority allocation strategy is proposed to generate a dynamic shared authority and achieve an adequate balance between lane keeping performance and driving freedom. Finally, a model predictive control (MPC)-based controller is designed for calculating optimal steering angle, and a steer-by-wheel (SBW) system is employed as an actuator. Numerical simulation tests are conducted on driver error scenarios based on the CarSim and MATLAB/Simulink software platforms. The simulation results demonstrate the effectiveness of the proposed method.
Full article
(This article belongs to the Special Issue Modelling, Control and Condition Monitoring of Actuator-Based Land Transport Systems)
Open AccessArticle
Model-Based Design Optimization of Soft Polymeric Domes Used as Nonlinear Biasing Systems for Dielectric Elastomer Actuators
by
, , , , and
Actuators 2021, 10(9), 209; https://doi.org/10.3390/act10090209 - 27 Aug 2021
Abstract
Due to their unique combination of features such as large deformation, high compliance, lightweight, energy efficiency, and scalability, dielectric elastomer (DE) transducers appear as highly promising for many application fields, such as soft robotics, wearables, as well as micro electro-mechanical systems (MEMS). To
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Due to their unique combination of features such as large deformation, high compliance, lightweight, energy efficiency, and scalability, dielectric elastomer (DE) transducers appear as highly promising for many application fields, such as soft robotics, wearables, as well as micro electro-mechanical systems (MEMS). To generate a stroke, a membrane DE actuator (DEA) must be coupled with a mechanical biasing system. It is well known that nonlinear elements, such as negative-rate biasing springs (NBS), permit a remarkable increase in the DEA stroke in comparison to standard linear springs. Common types of NBS, however, are generally manufactured with rigid components (e.g., steel beams, permanent magnets), thus they appear as unsuitable for the development of compliant actuators for soft robots and wearables. At the same time, rigid NBSs are hard to miniaturize and integrate in DE-based MEMS devices. This work presents a novel type of soft DEA system, in which a large stroke is obtained by using a fully polymeric dome as the NBS element. More specifically, in this paper we propose a model-based design procedure for high-performance DEAs, in which the stroke is maximized by properly optimizing the geometry of the biasing dome. First, a finite element model of the biasing system is introduced, describing how the geometric parameters of the dome affect its mechanical response. After conducting experimental calibration and validation, the model is used to develop a numerical design algorithm which finds the optimal dome geometry for a given DE membrane characteristics. Based on the optimized dome design, a soft DEA prototype is finally assembled and experimentally tested.
Full article
(This article belongs to the Special Issue Cooperative Microactuator Systems)
Open AccessArticle
Impact of the Confinement Plate on the Velocity of Synthetic Jet
by
and
Actuators 2021, 10(9), 208; https://doi.org/10.3390/act10090208 - 27 Aug 2021
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In the paper, the impact of the limitation of the environment around the office of synthetic jet actuators were tested. One short and three length orifices were tested and compared with and without confinement plate. In total, seven different synthetic jet actuators were
[...] Read more.
In the paper, the impact of the limitation of the environment around the office of synthetic jet actuators were tested. One short and three length orifices were tested and compared with and without confinement plate. In total, seven different synthetic jet actuators were investigated. The constant temperature anemometer was used for the velocity measurements. The synthetic jet was tested for the Reynolds number in the range of 2300 < Re < 19,500, and the Stokes number in the range of 46 < S < 62. The confinement plate decreased the velocity of synthetic jet depending on the actuator supply power even around 5%. However, the differences in axial velocity profile are slight and the impact of the confinement plate was visible only in the distance x/d < 4.
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Open AccessArticle
Optimized Control of Virtual Coupling at Junctions: A Cooperative Game-Based Approach
Actuators 2021, 10(9), 207; https://doi.org/10.3390/act10090207 - 27 Aug 2021
Abstract
Recently, virtual coupling has aroused increasing interest in regard to achieving flexible and on-demand train operations. However, one of the main challenges in increasing the throughput of a train network is to couple trains quickly at junctions. Pre-programmed train operation strategies cause trains
[...] Read more.
Recently, virtual coupling has aroused increasing interest in regard to achieving flexible and on-demand train operations. However, one of the main challenges in increasing the throughput of a train network is to couple trains quickly at junctions. Pre-programmed train operation strategies cause trains to decelerate or stop at junctions. Such strategies can reduce the coupling efficiency or even cause trains to fail to reach coupled status. To fill this critical gap, this paper proposes a cooperative game model to represent train coupling at junctions and adopts the Shapley theorem to solve the formulated game. Due to the discrete and high-dimensional characteristics of the model, the optimal solution method is non-convex and is difficult to solve in a reasonable amount of time. To find optimal operation strategies for large-scale models in a reasonable amount of time, we propose an improved particle swarm optimization algorithm by introducing self-adaptive parameters and a mutation method. This paper compares the strategy for train coupling at junctions generated by the proposed method with two naive strategies and unimproved particle swarm optimization. The results show that the operation time was reduced by using the proposed cooperative game-based optimization approach.
Full article
(This article belongs to the Special Issue Modelling, Control and Condition Monitoring of Actuator-Based Land Transport Systems)
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Open AccessArticle
Towards Essential Hand Tremor Suppression via Pneumatic Artificial Muscles
Actuators 2021, 10(9), 206; https://doi.org/10.3390/act10090206 - 26 Aug 2021
Abstract
Essential tremor (ET) is one of the most common movement disorders and can occur unexpectedly and develop indefinitely to any population unit. According to the recorded statistics of people suffering from ET, the disorder affects 5% of people worldwide, thus creating an ever-increasing
[...] Read more.
Essential tremor (ET) is one of the most common movement disorders and can occur unexpectedly and develop indefinitely to any population unit. According to the recorded statistics of people suffering from ET, the disorder affects 5% of people worldwide, thus creating an ever-increasing need to investigate ways for its suppression and treatment. In this article, we investigate the capability of Pneumatic Artificial Muscles (PAMs) to reduce or even suppress ET leading to the relief of the sufferers. In our work, we designed and constructed two iterations of a glovelike setup and attempted to explore the possibility of suppressing ET on different parts of the hand by exerting force on the index finger and metacarpal region. For both glove iterations, we established an experimental protocol based on the adjustment of a force controller. Finally, we evaluated exhaustively the performance of our setup under multiple motion scenarios with the participation of an ET-diagnosed volunteer.
Full article
(This article belongs to the Special Issue Soft Actuators for Artificial Muscles)
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Open AccessArticle
Active Exploration for Obstacle Detection on a Mobile Humanoid Robot
by
, , , , , and
Actuators 2021, 10(9), 205; https://doi.org/10.3390/act10090205 - 25 Aug 2021
Abstract
Conventional approaches to robot navigation in unstructured environments rely on information acquired from the LiDAR mounted on the robot base to detect and avoid obstacles. This approach fails to detect obstacles that are too small, or that are invisible because they are outside
[...] Read more.
Conventional approaches to robot navigation in unstructured environments rely on information acquired from the LiDAR mounted on the robot base to detect and avoid obstacles. This approach fails to detect obstacles that are too small, or that are invisible because they are outside the LiDAR’s field of view. A possible strategy is to integrate information from other sensors. In this paper, we explore the possibility of using depth information from a movable RGB-D camera mounted on the head of the robot, and investigate, in particular, active control strategies to effectively scan the environment. Existing works combine RGBD-D and 2D LiDAR data passively by fusing the current point-cloud from the RGB-D camera with the occupancy grid computed from the 2D LiDAR data, while the robot follows a given path. In contrast, we propose an optimization strategy that actively changes the position of the robot’s head, where the camera is mounted, at each point of the given navigation path; thus, we can fully exploit the RGB-D camera to detect, and hence avoid, obstacles undetected by the 2D LiDAR, such as overhanging obstacles or obstacles in blind spots. We validate our approach in both simulation environments to gather statistically significant data and real environments to show the applicability of our method to real robots. The platform used is the humanoid robot R1.
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(This article belongs to the Special Issue Intelligent Humanoid Mobile Robots)
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Open AccessArticle
Distributed Model Predictive Longitudinal Control for a Connected Autonomous Vehicle Platoon with Dynamic Information Flow Topology
Actuators 2021, 10(9), 204; https://doi.org/10.3390/act10090204 - 25 Aug 2021
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The development of vehicle-to-vehicle (V2V) improves the cooperation efficiency of the connected autonomous vehicle (CAV) platoon. However, the failure of the network communication occurs occasionally in the realistic environment, where the ideal fixed information flow topology (FIFT) cannot be adapted. To address this
[...] Read more.
The development of vehicle-to-vehicle (V2V) improves the cooperation efficiency of the connected autonomous vehicle (CAV) platoon. However, the failure of the network communication occurs occasionally in the realistic environment, where the ideal fixed information flow topology (FIFT) cannot be adapted. To address this issue, this paper proposes a dynamic information flow topology (DIFT) utilizing a distributed model predictive control (DMPC) algorithm for CAV platoons. When the communication link is broken, the platoon control system will switch to the corresponding collaborative control mode instead of the degeneration to adaptive cruise control (ACC). First, the duty-vehicle dynamic model is constructed. In addition, the constraints with vehicle physical limitations and rear-end collision are considered. The acceleration information of the pedal actuator from the leading vehicle and the states of the predecessor including position, velocity and acceleration are transmitted to the following vehicle with a switch Indicator under DIFT. The cost function with the consideration of DIFT and fuel consumption is formulated for the optimization problem. Comparing with the FIFT, the proposed method is evaluated in the co-simulation of Matlab-TruckSim. The results demonstrate that the proposed DIFT strategy shows the satisfactory performance of the platoon under the communication issues by measuring inter-vehicle space, position and velocity tracking, and acceleration change with high tracking accuracy of position within 1.2 m and velocity within 0.04 m/s.
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Open AccessArticle
Transmission Comparison for Cooperative Robotic Applications
Actuators 2021, 10(9), 203; https://doi.org/10.3390/act10090203 - 25 Aug 2021
Abstract
The development of powered assistive devices that integrate exoskeletal motors and muscle activation for gait restoration benefits from actuators with low backdrive torque. Such an approach enables motors to assist as needed while maximizing the joint torque muscles, contributing to movement, and facilitating
[...] Read more.
The development of powered assistive devices that integrate exoskeletal motors and muscle activation for gait restoration benefits from actuators with low backdrive torque. Such an approach enables motors to assist as needed while maximizing the joint torque muscles, contributing to movement, and facilitating ballistic motions instead of overcoming passive dynamics. Two electromechanical actuators were developed to determine the effect of two candidate transmission implementations for an exoskeletal joint. To differentiate the transmission effects, the devices utilized the same motor and similar gearing. One actuator included a commercially available harmonic drive transmission while the other incorporated a custom designed two-stage planetary transmission. Passive resistance and mechanical efficiency were determined based on isometric torque and passive resistance. The planetary-based actuator outperformed the harmonic-based actuator in all tests and would be more suitable for hybrid exoskeletons.
Full article
(This article belongs to the Section Actuators for Robotics)
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Open AccessArticle
Characterization and Analysis of a Flexural Shape Memory Alloy Actuator
Actuators 2021, 10(8), 202; https://doi.org/10.3390/act10080202 - 22 Aug 2021
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Shape memory alloys (SMAs) are popular as actuators for use in soft robots due to their high work density and compatibility with miniaturized on-board batteries and power electronics. However, because SMA actuators are activated through electrical Joule heating, they exhibit poor energy efficiency
[...] Read more.
Shape memory alloys (SMAs) are popular as actuators for use in soft robots due to their high work density and compatibility with miniaturized on-board batteries and power electronics. However, because SMA actuators are activated through electrical Joule heating, they exhibit poor energy efficiency and low actuator frequencies that arise from long cool-down times. Moreover, in the case of SMA wires that are subject to flexural loading, their load capacity and mechanical work output decrease exponentially with decreasing cross-sectional area. In this study, we perform analytic and numerical analyses to examine the thermal and structural design space around a particular class of flexural SMA wire actuators with the intention of increasing actuator operating frequency and actuation forces. Measurements obtained through experimental testing are consistent with theoretical studies of actuator force output and provide additional insight into the efficiency of electrical-to-mechanical energy conversion. Together, the theoretical and experimental studies provide insights that have the potential to inform SMA wire design and usage in soft robotic applications.
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Open AccessArticle
Adaptive Fuzzy Active-Disturbance Rejection Control-Based Reconfiguration Controller Design for Aircraft Anti-Skid Braking System
by
, , , , , and
Actuators 2021, 10(8), 201; https://doi.org/10.3390/act10080201 - 22 Aug 2021
Abstract
The aircraft anti-skid braking system (AABS) is an essential aero electromechanical system to ensure safe take-off, landing, and taxiing of aircraft. In addition to the strong nonlinearity, strong coupling, and time-varying parameters in aircraft dynamics, the faults of actuators, sensors, and other components
[...] Read more.
The aircraft anti-skid braking system (AABS) is an essential aero electromechanical system to ensure safe take-off, landing, and taxiing of aircraft. In addition to the strong nonlinearity, strong coupling, and time-varying parameters in aircraft dynamics, the faults of actuators, sensors, and other components can also seriously affect the safety and reliability of AABS. In this paper, a reconfiguration controller-based adaptive fuzzy active-disturbance rejection control (AFADRC) is proposed for AABS to meet increased performance demands in fault-perturbed conditions as well as those concerning reliability and safety requirements. The developed controller takes component faults, external disturbance, and measurement noise as the total perturbations, which are estimated by an adaptive extended state observer (AESO). The nonlinear state error feedback (NLSEF) combined with fuzzy logic can compensate for the adverse effects and ensure that the faulty AABS maintains acceptable performance. Numerical simulations are carried out in different runway environments. The results validate the robustness and reconfiguration control capability of the proposed method, which improves AABS safety as well as braking efficiency.
Full article
(This article belongs to the Special Issue Robust, Fault-Tolerant Control Design)
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Design and Analysis of a Stepping Piezoelectric Actuator Free of Backward Motion
Actuators 2021, 10(8), 200; https://doi.org/10.3390/act10080200 - 20 Aug 2021
Abstract
Although the stick-slip principle has been widely employed for designing piezoelectric actuators, there still exits an intrinsic drawback, i.e., the backward motion, which significantly affects its output performances and applications. By analyzing the generation mechanism of backward motion in stick-slip piezoelectric actuators, the
[...] Read more.
Although the stick-slip principle has been widely employed for designing piezoelectric actuators, there still exits an intrinsic drawback, i.e., the backward motion, which significantly affects its output performances and applications. By analyzing the generation mechanism of backward motion in stick-slip piezoelectric actuators, the elliptical trajectory was employed to design a novel stepping piezoelectric actuator free of backward motion. Accordingly, a prototype of piezoelectric actuator was designed, which utilized a flexure hinge mechanism and two vertically arranged piezoelectric stacks to generate the required elliptical trajectory. The compliance matrix method was used to theoretically analyze the flexure hinge mechanism. The theoretical and measured elliptical trajectories under various phase differences were compared, and the phase difference of 45° was selected accordingly. Under a critical relative gap, output performances of the actuator working under the elliptical trajectory were characterized, and then compared with that obtained under the normal stick-slip driving principle. Experimental results indicated that forward and reverse stepping displacement with completely suppressed backward motion could be achieved when employing the elliptical trajectory, verifying its feasibility. This study provides a new strategy for designing a stepping piezoelectric actuator free of backward motion.
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(This article belongs to the Special Issue Design of Sensing and Actuation Systems)
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Open AccessArticle
Design of Two-Axial Actuator for Controlled Vibration Damper for Large Rams
Actuators 2021, 10(8), 199; https://doi.org/10.3390/act10080199 - 19 Aug 2021
Abstract
Machine tool rams are important constructional elements found on vertical lathes as well as on many other machines. In most cases, a machine tool ram constitutes an assembly with significant dynamic compliance that affects the machine’s ability to achieve stable cutting conditions. There
[...] Read more.
Machine tool rams are important constructional elements found on vertical lathes as well as on many other machines. In most cases, a machine tool ram constitutes an assembly with significant dynamic compliance that affects the machine’s ability to achieve stable cutting conditions. There are various solutions for increasing a machine tool ram’s stiffness and damping. This paper describes an innovative concept of a two-axial electromagnetic actuator for controlled vibration dampers with high dynamic force values. The described solution is purposefully based on the use of standard electric drives. As a result, the size of the actuator is easier to scale to the required application. The solution is designed as a spacer between the end of the ram and the head. The paper presents the actuator concept, construction design, current control loop solution and experimental verification of the controlled vibration damper’s function on the test ram in detail. The presented position measurement concept will enable the use of non-contact position sensors for motor commutation as well as for possible use in vibration suppression control. Applications can be expected mainly in the field of vibration suppression of vertical rams of large machine tools.
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(This article belongs to the Special Issue Vibration Control and Structure Health Monitoring)
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Open AccessArticle
Mechanical Design and Performance Analyses of a Rubber-Based Peristaltic Micro-Dosing Pump
Actuators 2021, 10(8), 198; https://doi.org/10.3390/act10080198 - 19 Aug 2021
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Low pressure fluid transport (1) applications often require low and precise volumetric flow rates (2) including low leakage to reduce additional costly and complex sensors. A peristaltic pump design (3) was realized, with the fluid’s flexible transport channel formed by a solid cavity
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Low pressure fluid transport (1) applications often require low and precise volumetric flow rates (2) including low leakage to reduce additional costly and complex sensors. A peristaltic pump design (3) was realized, with the fluid’s flexible transport channel formed by a solid cavity and a wobbling plate comprising a rigid and a soft layer (4). In operation, the wobbling plate is driven externally by an electric motor, hence, the soft layer is contracted and unloaded (5) during pump-cycles transporting fluid from low to high pressure sides. A thorough characterization of the pump system is required to design and dimension the components of the peristaltic pump. To capture all these parameters and their dependencies on various operation-states, often complex and long-lasting dynamic 3D FE-simulations are required. We present, here, a holistic design methodology (6) including analytical as well as numerical calculations, and experimental validations for a peristaltic pump with certain specifications of flow-rate range, maximum pressures, and temperatures. An experimental material selection process is established and material data of candidate materials (7) (liquid silicone rubber, acrylonitrile rubber, thermoplastic-elastomer) are directly applied to predict the required drive torque. For the prediction, a semi-physical, analytical model was derived and validated by characterizing the pump prototype.
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Open AccessArticle
Distributed Secure Edge Computing Architecture Based on Blockchain for Real-Time Data Integrity in IoT Environments
Actuators 2021, 10(8), 197; https://doi.org/10.3390/act10080197 - 13 Aug 2021
Abstract
The traditional cloud-based Internet of Things (IoT) architecture places extremely high demands on computers and storage on cloud servers. At the same time, the strong dependence on centralized servers causes major trust problems. Blockchain provides immutability, transparency, and data encryption based on safety
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The traditional cloud-based Internet of Things (IoT) architecture places extremely high demands on computers and storage on cloud servers. At the same time, the strong dependence on centralized servers causes major trust problems. Blockchain provides immutability, transparency, and data encryption based on safety to solve these problems of the IoT. In this paper, we present a distributed secure edge computing architecture using multiple data storages and blockchain agents for the real-time context data integrity in the IoT environment. The proposed distributed secure edge computing architecture provides reliable access and an unlimited repository for scalable and secure transactions. The architecture eliminates traditional centralized servers using an edge computing framework that represents cloud computing for computer and security issues. Also, blockchain-based edge computing-compatible IoT design is supported to achieve the level of security and scalability required for data integrity. Furthermore, we present the blockchain agent to provide internetworking between blockchain networks and edge computing. For experimenting with the proposed architecture in the IoT environment, we implement and perform a concrete IoT environment based on the EdgeX framework and Hyperledger Fabric. The evaluation results are collected by measuring the performance of the edge computing and blockchain platform based on service execution time to verify the proposed architecture in the IoT environment.
Full article
(This article belongs to the Special Issue Sensing and Actuating Tasks in IoT Environments)
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H∞ Reliable Dynamic Output-Feedback Controller Design for Discrete-Time Singular Systems with Sensor Saturation
Actuators 2021, 10(8), 196; https://doi.org/10.3390/act10080196 - 13 Aug 2021
Abstract
In this study, we investigate the H∞ fault-tolerant control problem for a discrete-time singular system which is subject to external disturbances, actuator faults, and sensor saturation. By assuming that the state variable of the system is unavailable for measurement, and the actuator
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In this study, we investigate the H∞ fault-tolerant control problem for a discrete-time singular system which is subject to external disturbances, actuator faults, and sensor saturation. By assuming that the state variable of the system is unavailable for measurement, and the actuator fault can be described by a Markovian jump process, attention is mainly focused on designing a reliable dynamic output-feedback (DOF) controller able to compensate for the effects of the aforementioned factors on the system stability and performance. Based on the sector non-linear approach to handle the sensor saturation, a new criterion is established to ensure that the closed-loop system is stochastically admissible with a level of the H∞ disturbance rejection performance. The main aim of this work is to develop a procedure for synthesizing the controller gains without any model transformation or decomposition of the output matrix. Therefore, by introducing a slack variable, the H∞ admissibility criterion is successfully transformed in terms of strict linear matrix inequalities (LMIs). Three practical examples are exploited to test the feasibility and effectiveness of the proposed approach.
Full article
(This article belongs to the Special Issue Robust, Fault-Tolerant Control Design)
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Open AccessArticle
The Development of an Optimally-Tuned PID Control for the Actuator of a Transport Robot
by
and
Actuators 2021, 10(8), 195; https://doi.org/10.3390/act10080195 - 12 Aug 2021
Abstract
An optimally-tuned PID control for a transport robot actuator based on an induction motor was developed. Continuous-discrete and continuous mathematical models of the actuator were obtained. The parametric synthesis of PID controller on the basis of continuous and discrete actuator models were performed.
[...] Read more.
An optimally-tuned PID control for a transport robot actuator based on an induction motor was developed. Continuous-discrete and continuous mathematical models of the actuator were obtained. The parametric synthesis of PID controller on the basis of continuous and discrete actuator models were performed. Numerical simulations using SimInTech for the adaptive regulator taking into account the cargo weight (from empty to maximum loaded) were carried out. The scheme of automatic selection of actuator PID coefficients considering the cargo weight was proposed. The scheme of automatic selection of coefficients of PID regulator for an actuator with regard to the cargo weight was suggested. As a result of parametric synthesis of discrete PID control law optimum values of its amplification coefficients were determined. There was no overcontrol and the transient time, which satisfied the initial requirements for the optimization of the control algorithm by angular velocity.
Full article
(This article belongs to the Special Issue Actuators in Manufacturing Robotics and Mechatronics)
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Open AccessArticle
A New Method for Friction Estimation in EMA Transmissions
by
, , , and
Actuators 2021, 10(8), 194; https://doi.org/10.3390/act10080194 - 11 Aug 2021
Abstract
The increasing interest for adopting electromechanical actuators (EMAs) on aircraft demands improved diagnostic and prognostic methodologies to be applied to such systems in order to guarantee acceptable levels of reliability and safety. While diagnostics methods and techniques can help prevent fault propagation and
[...] Read more.
The increasing interest for adopting electromechanical actuators (EMAs) on aircraft demands improved diagnostic and prognostic methodologies to be applied to such systems in order to guarantee acceptable levels of reliability and safety. While diagnostics methods and techniques can help prevent fault propagation and performance degradation, prognostic methods can be applied in tandem to reduce maintenance costs and increase overall safety by enabling predictive and condition-based maintenance schedules. In this work, a predictive approach for EMAs friction torque estimation is proposed. The algorithm is based on the reconstruction of the residual torque in mechanical transmissions. The quantity is then sampled and an artificial neural network (ANN) is used to obtain an estimation of the current health status of the transmission. Early results demonstrate that such an approach can predict the transmission health status with good accuracy.
Full article
(This article belongs to the Special Issue Health Monitoring and Fault Diagnosis on Actuation Systems)
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Open AccessArticle
Observer-Based Coordinated Control for Blended Braking System with Actuator Delay
Actuators 2021, 10(8), 193; https://doi.org/10.3390/act10080193 - 11 Aug 2021
Abstract
The coordinated control of a blended braking system is always a difficult task. In particular, blended braking control becomes more challenging when the braking actuator has an input time-delay and some states of the braking system cannot be measured. In order to improve
[...] Read more.
The coordinated control of a blended braking system is always a difficult task. In particular, blended braking control becomes more challenging when the braking actuator has an input time-delay and some states of the braking system cannot be measured. In order to improve the tracking performance, a coordinated control system was designed based on the input time-delay and state observation for a blended braking system comprising a motor braking system and friction braking system. The coordinated control consists of three parts: Sliding mode control, a multi-input single-output observer, and time-delay estimation-based Smith Predictor control. The sliding mode control is used to calculate the total command braking torque according to the desired braking performance and vehicle states. The multi-input single-output observer is used to simultaneously estimate the input time-delay and output braking torque of the friction braking system. With time-delay estimation-based Smith Predictor control, the friction braking system is able to effectively track the command braking torque of the friction braking system. The tracking of command braking torque is realized through the coordinated control of the motor braking system and friction braking system. In order to validate the effectiveness of the proposed approach, numerical simulations on a quarter-vehicle braking model were performed.
Full article
(This article belongs to the Special Issue Vehicle Modeling and Control)
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Special Issue in
Actuators
Smart Actuators for Endoscopic Robots
Guest Editor: Luigi ManfrediDeadline: 30 September 2021
Special Issue in
Actuators
Vehicle Modeling and Control
Guest Editors: Olivier Sename, Van Tan Vu, Thanh-Phong PhamDeadline: 15 October 2021


