Actuators MDPI

📢📢 /Actuators/ Receives an Increased CiteScore of 3.9 We are pleased to inform you that /Actuators/ (ISSN: 2076-0825 ) has received a heightened CiteScore of 3.9. The 2023 CiteScore provides an assessment of the scientific influence of journals in the 2020 to 2023 period. This is a reflection of the excellent performance, support, and dedication of all journal editors, reviewers, authors, and readers. Actuators CiteScore ranks as follows: Q2 (37 out of 130) in "Control and Optimization". Q2 (131 out of 321) in "Control and Systems Engineering". Q2 (131 out of 321) in "Engineering". For more journal statistics, please visit https://lnkd.in/gmZ-HAMi Thank you to everyone who has contributed to the journal.

#Article 📜 A Bimodal Hydrostatic Actuator for Robotic Legs with Compliant Fast Motion and High Lifting Force by Alex Lecavalier, Jeff Denis, Jean-Sébastien Plante and Alexandre Girard 🔗 https://lnkd.in/gPjQQCQB MDPI; Université de Sherbrooke #roboticleg #wearablerobot #leggedlocomotion #dualspeedactuator #hydrostatictransmission #gearshifting #forcebandwidth #Abstract Robotic legs, such as for lower-limb exoskeletons and prostheses, have bimodal operation: (1) within a task, like for walking (high speed and low force for the swing phase and low speed and higher force when the leg bears the weight of the system); (2) between tasks, like between walking and sit–stand motions. Sizing a traditional single-ratio actuation system for such extremum operations leads to oversized heavy electric motor and poor energy efficiency at low speeds. This paper explores a bimodal actuation concept where a hydrostatic transmission is dynamically reconfigured using custom motorized ball valves to suit the requirements of a robotic leg with a smaller and more efficient actuation system. First, this paper presents an analysis of the mass and efficiency advantages of the bimodal solution over a baseline solution, for three operating points: high-speed, high-force, and braking modes. Second, an experimental demonstration with a custom-built actuation system and a robotic leg test bench is presented.

#Article 📜 Development of Vibratory Microinjection System for Instantaneous Cell Membrane Piercing in Cytoplasmic Microinjection into Fertilized Eggs by Fujio Miyawaki and Jun Hasegawa 🔗 https://lnkd.in/gwCVECFV MDPI; Tokyo Denki University; Takushoku University #VibratoryMicroinjectionSystem #vibrationpropagationmechanism #vibrator #ultrasonicvibration #Abstract To complete microinjection as quickly as possible, we have developed Vibratory Microinjection Systems (VMSs) that vibrate a micropipette in its longitudinal direction and can significantly reduce the time needed for pronuclear microinjection compared to ordinary (non-vibratory) microinjection. The longest breakdown of the time is the time required to pierce the cell membrane and the pronuclear membrane simultaneously. Because cytoplasmic microinjection, which pierces the cell membrane alone, is far more difficult and time-consuming than pronuclear microinjection, we next aimed to develop a VMS capable of penetrating the cell membrane instantly. In this new and latest version, two types of ultrasonic-wave vibrators were developed: the first for commercially available micropipettes (Femtotip) and the second for self-made micropipettes. The two vibrators differ only in their airtight structure, where the micropipettes connect to their respective vibrators: a female screw plus O-ring for the first vibrator (VMS6_1) and a silicone-rubber tube for the second (VMS6_2).

#Article 📜 Observer-Based Nonlinear Proportional–Integral–Integral Speed Control for Servo Drive Applications via Order Reduction Technique by Yonghun Kim, Hyunho Ye, Sun Lim and Seok-Kyoon Kim 🔗 https://lnkd.in/g5_qjr9Y MDPI; Chungnam National University; KETI(Korea Electronics Technology Institute); Hanbat National University #speedcontrol #activedamping #observer #servodrive #Abstract This study designs an advanced single-loop output feedback system for speed servo drive applications, in which a simple proportional–integral–integral (PII) controller equipped with nonlinear feedback and feed-forward gains is formed. The resultant feedback system shows the desired critically damped performance for wide-operating regions by actively handling the system parameter and load uncertainties. There are three contributions: first, the third-order observer estimates, independent from the system model, where the speed and acceleration are obtained using the position measurement with the order reduction property; second, the observer-based PII controller is compensated by active damping with a nonlinearly structured feedback and feed-forward gains; and, third, a guarantee is achieved on the desired critically damped performance through a closed-loop analysis. A hardware testbed that adopts a 500 W brushless DC motor is used to experimentally demonstrate performance improvements over certain constant torque regions under various scenarios.

#Article 📜 Man-Power-Amplifying Exoskeleton with Pneumatic Actuator by Francesco Durante, terenziano raparelli and Pierluigi Beomonte Zobel 🔗 https://lnkd.in/gEb-uBgq MDPI; University of L'Aquila; Politecnico di Torino #manpoweramplifier #control #pneumatic #exoskeleton #admittancecontrol #cobot #Abstract This study describes the activity of developing a force amplifier exoskeleton with one degree of freedom. The system was developed as a research prototype to conduct control system studies. The device consists of an arm with a pneumatic cylinder actuator controlled by a pressure regulator. As for the human–machine interface, the system has a force sensor. The idea is to verify the possibility of developing a simple system from the sensor system’s point of view and the control system’s architecture while simultaneously obtaining an effective, economical, and reliable device. The idea developed in this project is to use the user’s available ability to control movements in unknown environments. The user constitutes the central part of the entire control system: he defines the references for the speeds and forces to be applied to the environment and observes the rates of the controlled robotic system through his own sight and proprioceptive system. On the other hand, the machine produces and controls the forces applied to the environment by the actuator. In this way, the device shows an increased admittance. A mathematical system model was created to verify the idea’s feasibility. Following the results of the simulations, a prototype was built on which experimental tests were carried out.

#Article 📜 A Novel Hierarchical Recursive Nonsingular Terminal Sliding Mode Control for Inverted Pendulum by Hiep Dai Le and Tamara Nestorović 🔗 https://lnkd.in/g-gfkzJG MDPI; Ruhr University Bochum #adaptiveslidingmodecontrol #uncertainties #invertedpendulum #underactuatedsystem #Abstract This paper aims to develop a novel hierarchical recursive nonsingular terminal sliding mode controller (HRNTSMC), which is designed to stabilize the inverted pendulum (IP). In contrast to existing hierarchical sliding mode controllers (HSMC), the HRNTSMC significantly reduces the chattering problem in control input and improves the convergence speed of errors. In the HRNTSMC design, the IP system is first decoupled into pendulum and cart subsystems. Subsequently, a recursive nonsingular terminal sliding mode controller (RNTSMC) surface is devised for each subsystem to enhance the error convergence rate and attenuate chattering effects. Following this design, the HRNTSMC surface is constructed by the linear combination of the RNTSMC surfaces. Ultimately, the control law of the HRNTSMC is synthesized using the Lyapunov theorem to ensure that the system states converge to zero within a finite time. By invoking disturbances estimation, a linear extended state observer (LESO) is developed for the IP system. To validate the effectiveness, simulation results, including comparison with a conventional hierarchical sliding mode control (CHSMC) and a hierarchical nonsingular terminal sliding mode control (HNTSMC) are presented. These results clearly showcase the excellent performance of this approach, which is characterized by its strong robustness, fast convergence, high tracking accuracy, and reduced chattering in control input.

#Article 📜 Plasma Actuators for Cycloidal Rotor Thrust Vectoring Enhancement in Airships by Amine Benmoussa, Frederico F. Rodrigues and José C. Páscoa 🔗 https://lnkd.in/ghT2-FGV MDPI; Universidade da Beira Interior #DBDplasmaactuators #flowcontrol #cycloidalrotors #airships #Abstract Airships are a method of transportation with reduced fuel consumption and great potential for different applications. However, these aerial vehicles still present considerable control and maneuverability problems. To overcome these issues, in the current work, we propose the use of plasma-enhanced cycloidal rotor thrusters to increase the controllability and maneuverability of airships. Numerical simulations are carried out to demonstrate the potential of plasma actuators to enhance the efficiency and thrust vectoring capabilities of cycloidal rotors. The fluid dynamics of the flow effects created via the operation of the cycloidal rotor is analyzed with and without plasma actuation. In addition, smart combined plasma actuation is proposed to further optimize the plasma-coupled cycloidal rotor device. The results demonstrated that by using this novel approach, the lift coefficient was increased by about 27%. To summarize, the obtained results for a rotational speed of 100 rpm are compared with results for 200 rpm, and it is demonstrated that for lower rotational speeds, the plasma effect is increased and more significant. This allows us to conclude that airships are an ideal application for plasma-enhanced cycloidal rotors, because since the lift is mostly generated via aerostatic principles, the plasma-enhanced thruster can be operated at lower rotational speeds and effectively increase the controllability and maneuverability of the aerial vehicle.

#Article 📜 EEG Investigation on the Tactile Perceptual Performance of a Pneumatic Wearable Display of Softness by Federico Carpi, Michele C. Valles, Gabriele Frediani, Tanita Toci and Antonello Grippo 🔗 https://lnkd.in/gADcpa9t MDPI; Università degli Studi di Firenze #tactile #display #wearable #softness #stimulation #somatosensoryevokedpotential #EEG #Abstract Multisensory human–machine interfaces for virtual- or augmented-reality systems are lacking wearable actuated devices that can provide users with tactile feedback on the softness of virtual objects. They are needed for a variety of uses, such as medical simulators, tele-operation systems and tele-presence environments. Such interfaces require actuators that can generate proper tactile feedback, by stimulating the fingertips via quasi-static (non-vibratory) forces, delivered through a deformable surface, so as to control both the contact area and the indentation depth. The actuators should combine a compact and lightweight structure with ease and safety of use, as well as low costs. Among the few actuation technologies that can comply with such requirements, pneumatic driving appears to be one of the most promising. Here, we present an investigation on a new type of pneumatic wearable tactile displays of softness, recently described by our group, which consist of small inflatable chambers arranged at the fingertips. In order to objectively assess the perceptual response that they can elicit, a systematic electroencephalographic study was conducted on ten healthy subjects.

#Article 📜 Design and Testing of Disconnection Actuators for Enhancing Safety and Preventing Failure Escalation by Yusuf Akcay, Oliver Tweedy, Paolo Giangrande and Michael Galea 🔗 https://lnkd.in/ghuyUN43 MDPI; The University of Sheffield; University of Nottingham; Università degli Studi di Bergamo; University of Malta #electromagneticdevice #magneticcoupling #reliability #faultmitigation #disconnectionactuator #Abstract The growing demand for reliability has led to an increased interest in developing effective disconnection systems for enhancing the safety of and preventing failure escalation in engineering systems. Considering this prospect, the design optimization of two disconnection actuators composed of a coaxial magnetic coupling linked to an electromagnetic device is presented and discussed. The disconnection actuator delivers a contactless torque transmission through the coaxial magnetic coupling, whereas the torque transfer is interrupted by the electromagnetic device in case a failure is detected via a dedicated algorithm. The performed design procedure relies on 2D finite element analysis, and trade-off studies are carried out to achieve an optimized geometry of an electromagnetic device. Finally, two disconnection actuators, for high-speed and high-torque applications, are prototyped and tested, with the aim of evaluating their disconnection capability. For both disconnection actuators, the developed force and voltage–current characteristics are measured along with the disconnection time.

#Article 📜 Mechanical Property Degradation of Entangled Metallic Wire Materials under Vibration Environment: Experiments and Prediction Models by Yanhong Ma, Tianyu Liang, yongfeng wang, Zhizhou Wang and Jie Hong 🔗 https://lnkd.in/gKFK6FsV MDPI; Beihang University #entangledmetallicwirematerial #vibrationexperiment #cycliccompressiveloads #predictionmodel #Abstract Entangled metallic wire material (EMWM) can be utilized as a novel elastic element in vibration isolation devices for mechanical actuators. This paper presents a vibration experiment aimed at investigating the degradation behavior of mechanical performance in EMWM under a cyclic compressive environment. An electric vibration testing system, coupled with an isolation structure, is employed to apply compressive loads to the EMWM specimens. Through visual observations and quasi-static compression tests, the variations in geometric morphology and mechanical properties are studied, considering different relative densities and vibrational stress amplitudes. The results indicate a significant reduction in the compressed dimension of the specimens as the number of cycles increases, without any wire fractures or wear. The mechanical properties exhibit an increasing secant modulus and a decreasing loss factor. These variations ultimately lead to a gradual deviation of the vibration characteristics of the isolation structure from its design state, including resonance frequency and transmission rate. To forecast the mechanical property degradation of EMWM, prediction models are proposed, incorporating its dimensions, modulus, and damping by fitting the experiment results. This research provides valuable experimental data and presents an effective method to determine the operational lifespan of vibration isolators utilizing EMWM.