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Actuators, Volume 9, Issue 3 (September 2020) – 6 articles

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Open AccessArticle
An Equivalent Circuit Analysis and Suspension Characteristics of AC Magnetic Suspension Using Magnetic Resonant Coupling
Actuators 2020, 9(3), 52; https://doi.org/10.3390/act9030052 - 09 Jul 2020
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Abstract
The fundamental characteristics and performances of alternating current (AC) magnetic suspension using magnetic resonant coupling are studied analytically and experimentally. Nowadays, wireless power transfer to the suspended object is required during non-contact suspension in some applications. Therefore, magnetic resonant coupling has been introduced [...] Read more.
The fundamental characteristics and performances of alternating current (AC) magnetic suspension using magnetic resonant coupling are studied analytically and experimentally. Nowadays, wireless power transfer to the suspended object is required during non-contact suspension in some applications. Therefore, magnetic resonant coupling has been introduced for AC magnetic suspension to achieve self-stabilizing magnetic suspension and energy transfer to the floator simultaneously. The effect of circuit parameters for developing an experimental apparatus and performances are predicted from the solution of the equivalent circuits analytically. First, an equivalent magnetic circuit is derived and analyzed to characterize the self-inductance and mutual inductance with the gap. Second, an equivalent electrical circuit is analyzed to derive the current and force equations including magnetic parameters of the circuit. The derivation of these equations is numerically solved to study the characteristics of the primary current, the secondary current, and the force with respect to the gap and the applied frequency. The comparison between theoretical and experimental results is depicted, and the reason for differences is explained. The experimental and theoretical results show that positive stiffness is possible, which is essential for achieving self-stabilization. The self-stability is confirmed by the frequency response of the suspension system to disturbance experimentally. Full article
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Open AccessArticle
A New Type of Rotary Magnetic Actuator System Using Electromagnetic Vibration and Wheel
Actuators 2020, 9(3), 51; https://doi.org/10.3390/act9030051 - 06 Jul 2020
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Abstract
In recent years, large structures, such as bridges, which are a type of social infrastructure, have been constructed with increasing traffic volume. For this reason, inspection and maintenance of social infrastructures, such as large bridges and tanks, is important. In the present paper, [...] Read more.
In recent years, large structures, such as bridges, which are a type of social infrastructure, have been constructed with increasing traffic volume. For this reason, inspection and maintenance of social infrastructures, such as large bridges and tanks, is important. In the present paper, a magnetic wheel actuator system capable of movement using a new principle of locomotion was proposed and tested. The experimental results indicated a maximum pulling force of 1.6 N. By on-off control of the attractive force of the magnetic wheel, the actuator system was demonstrated to be able to move on a step having a height of 10 mm. Furthermore, the proposed actuator system could freely rotate in horizontal and vertical planes of over angles of 360°. Full article
(This article belongs to the Section Actuators for Robotics)
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Open AccessArticle
Innovative Actuator Fault Identification Based on Back Electromotive Force Reconstruction
Actuators 2020, 9(3), 50; https://doi.org/10.3390/act9030050 - 03 Jul 2020
Viewed by 277
Abstract
The ever increasing adoption of electrical power as secondary form of on-board power is leading to an increase in the usage of electromechanical actuators (EMAs). Thus, in order to maintain an acceptable level of safety and reliability, innovative prognostics and diagnostics methodologies are [...] Read more.
The ever increasing adoption of electrical power as secondary form of on-board power is leading to an increase in the usage of electromechanical actuators (EMAs). Thus, in order to maintain an acceptable level of safety and reliability, innovative prognostics and diagnostics methodologies are needed to prevent performance degradation and/or faults propagation. Furthermore, the use of effective prognostics methodologies carries several benefits, including improved maintenance schedule capability and relative cost decrease, better knowledge of systems health status and performance estimation. In this work, a novel, real-time approach to EMAs prognostics is proposed. The reconstructed back electromotive force (back-EMF), determined using a virtual sensor approach, is sampled and then used to train an artificial neural network (ANN) in order to evaluate the current system status and to detect possible coils partial shorts and rotor imbalances. Full article
(This article belongs to the Section Aircraft Actuators)
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Open AccessLetter
Analysis of the Possibilities of Using a Driver’s Brain Activity to Pneumatically Actuate a Secondary Foot Brake Pedal
Actuators 2020, 9(3), 49; https://doi.org/10.3390/act9030049 - 01 Jul 2020
Viewed by 266
Abstract
The study deals with the use of the driver’s brain activity for wireless remote control of the pneumatic actuator exerting pressure on the secondary foot brake pedal. The conducted experimental tests confirm that bioelectrical signals (BES) induced by muscle tension within the head [...] Read more.
The study deals with the use of the driver’s brain activity for wireless remote control of the pneumatic actuator exerting pressure on the secondary foot brake pedal. The conducted experimental tests confirm that bioelectrical signals (BES) induced by muscle tension within the head can be used for wireless remote control of a pneumatic actuator to exert a pressure force on a foot brake pedal for disabled drivers during car emergency braking. It has been shown that the BES artefacts generated by muscular tension inside the head (e.g., movement of the face and eyelids, clenching of jaws, and pressing the tongue on the palate) are the easiest to control of the pneumatic systems. The proposed car braking assistance system controlled by the driver’s brain activity can improve the driving safety of disabled people, e.g., by reducing the reaction time of pneumatically assisted emergency braking. Full article
(This article belongs to the Special Issue Variable Stiffness Actuators)
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Open AccessArticle
Design of Tendon-Driven Mechanism Using Geometrical Condition
Actuators 2020, 9(3), 48; https://doi.org/10.3390/act9030048 - 30 Jun 2020
Viewed by 308
Abstract
A tendon-driven robot offers many advantages, such as easy designs for mass distribution that facilitate dexterous motion. A procedure to design such a robot using a single actuator to achieve the desired force direction and magnitude on an endpoint is presented herein. The [...] Read more.
A tendon-driven robot offers many advantages, such as easy designs for mass distribution that facilitate dexterous motion. A procedure to design such a robot using a single actuator to achieve the desired force direction and magnitude on an endpoint is presented herein. The force on the endpoint is generated by the single actuator and a wire that passes through pulleys attached on links. To set the pulley position for the desired force direction and magnitude, a geometrical condition is proposed. To evaluate the proposed method, a physical monopod robot was developed. We compared the calculated and physical forces on the endpoint of the physical robot for the desired directions. Finally, we confirmed that the proposed method provided the desired force on the endpoint without iterative trials. Full article
(This article belongs to the Section Actuators for Robotics)
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Open AccessArticle
Proposal of an Equal-Stiffness and Equal-Stroke 2D Micro-Positioning Platform Driven by Piezoelectric Actuators
Actuators 2020, 9(3), 47; https://doi.org/10.3390/act9030047 - 29 Jun 2020
Viewed by 374
Abstract
Micro-positioning platform plays an important role in the field of precision positioning such as microelectronics, robotics and biomedicine. This paper proposes an equal-stiffness and equal-stroke 2D micro-positioning platform, which is driven by piezoelectric actuators. The overall structure of the 2D micro-positioning platform adopts [...] Read more.
Micro-positioning platform plays an important role in the field of precision positioning such as microelectronics, robotics and biomedicine. This paper proposes an equal-stiffness and equal-stroke 2D micro-positioning platform, which is driven by piezoelectric actuators. The overall structure of the 2D micro-positioning platform adopts a nested structure and the displacement magnification mechanism adopts two hourglass displacement magnification mechanisms. The displacement magnification ratio of the hourglass displacement magnification mechanism was studied, and its structural parameters were optimized. Static stiffness analysis and simulation analysis of the micro-positioning platform were carried out. The simulation stiffness of the micro-positioning platform in the XY direction is 46873 N/m and 46832 N/m respectively. The experimental prototype of the micro-positioning platform was built. Through the measurement experiment with the prototype, the maximum stroke of the micro-positioning platform in the XY direction is 489 μm and 493 μm respectively; the maximum coupling ratio in the XY direction is 2.38% and 2.70% respectively. The research indicates that the micro-positioning platform had the characteristics of small size, equal long stroke, equal stiffness and low coupling ratio in the XY direction. Full article
(This article belongs to the Special Issue Piezoelectric Actuators and Ultrasonic Motors: Future Perspectives)
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