Actuation Efficiency Research Articles

Part Design of Giant Magnetostrictive Actuator

The key parts of giant magnetostrictive actuator, flexure hinge and pre-stress disc spring, were designed and analyzed. Rotation stiffness and strength characteristics of flexure hinge were analyzed, calculation equations for rotation stiffness and strength were established as well. Fatigue characteristic was also analyzed as flexure hinge usually worked under high frequency situation. In order to improve output efficiency of the giant magnetostrictive actuator and reduce energy loss, an ideal spring force-deformation curve, whose shape was bilinear broken line, of the pre- stress disc spring was put forward, and a disc spring was designed by configuring its geometric parameters to make its spring force-deformation curve was approximate to the ideal spring force-deformation curve.

216104 DBDプラズマアクチュエータの基本的特性に関する研究(一般05 流体力学・流体工学2)

Drag reduction is a technical issue on the reduction of carbon dioxide gas emission. Particularly, DBD plasma actuator is a promising technology on active control of the flow separation. In the present work, efficiency of the plasma actuator is investigated experimentally for a variety of parameters including dielectric material, thickness of the dielectric plate, and gap between two electrodes. It is found that: (a) efficiency increases substantially with decreasing thickness of the dielectric plate, however maximum value exists for the applied voltage; (b) as for materials, efficiency of polytetrafluoroethylene (PTFE) is 〜400% larger compared to polyoxybenzylmethylenglycolanhydride (Bakelite).

Ionic Electroactive Polymer Actuators with Aligned Carbon Nanotube/Nafion Nanocomposite Electrodes

ABSTRACTRecent advances in fabricating controlled-morphology vertically aligned carbon nanotube (VA-CNTs) with ultrahigh volume fraction create unique opportunities for markedly improving the electromechanical performance of ionic polymer conductor network composite actuators (IPCNCs). Actuator experiments show that the continuous paths through inter-VA-CNT channels and low electrical conduction resistance due to the continuous CNTs in the composite electrodes of the IPCNC lead to fast ion transport and actuation speed (>10% strain/second). One critical issue in developing advanced actuator materials is how to suppress or eliminate unwanted strains generated under electric stimulation, which reduce the actuation efficiency and also the actuation strains. We observe that the VA-CNTs in the composite electrodes yields non-isotropic elastic modulus that suppresses the unwanted strain and markedly enhances the actuation strain (>8% strain under 4 volts). A transmission line model has been developed to understand the electrical properties of the actuator device.

Research and Application of Dynamic Substitution Control of Actuators in Flatness Control of Cold Rolling Mill

AbstractThe work roll bending control has a strong ability to eliminate the symmetrical flatness defects of strip. However, if the incoming strip is coming with severe symmetrical flatness defects, it happens that the position limit of work roll bending is prone to be reached or exceeded during the execution of the displacement, resulting in the residual symmetrical flatness defects without further elimination, as well as a limited flatness control process. Abilities of work roll bending and intermediate roll bending / shifting for flatness control have been analyzed based on the actuator efficiencies for the purpose of solving the problem of work roll bending control reaching threshold. Meanwhile, a self‐learning determination model of actuator efficiency factors, which can be utilized to determine the actuator efficiency factors online accurately, was developed from the measurement data extracted from the rolling mill. Models of intermediate roll bending and intermediate roll shifting substitution control in case of work roll bending control over‐limitation have been developed, in accordance with the practical conditions and the degree of work roll bending over‐limitation. Applications show that the substitution control can play an important role in the residual symmetrical flatness deviation control, which should have been removed completely by the work roll bending control.

Magnetic Torque Evaluation for Magnetized Nanoparticles

The efficiency of the magnetic actuation is studied using ideal magnetized nano-ellipsoids under an applied magnetic field. The volumetric magnetic torque is evaluated and the influence of the particle shape, orientation and anisotropy is outlined.

Thermally driven multi-layer actuator for 2D cantilever arrays

The present work reports on novel four-layer thermally driven piezoresistive cantilevers implemented in one- and two-dimensional arrays for parallel proximity scanning. There, the heater (metallic meander), the piezoresistive deflection sensor, and the metal actuation film with significantly higher thermal expansion coefficient make up separate layers. Actuation efficiency and cross-talk of the novel cantilever design are studied and compared with two recent designs: thin metallic film and ion-implanted heater. The novel actuator, integrated on a 240 μm long and 3 μm thick silicon cantilever and supplied by Vdc=1 V enables deflections up to 5 μm of the AFM-tip with an actuation efficiency of about 170 nm/mW and suppressed cross-talk between actuator and sensor.

A Robust Model for Work Roll Bending Control Reaching Threshold in Flatness Control of Cold Rolling Mill

The work roll bending is one of the most effective flatness actuators in flatness control of cold rolled strips, as a result of its characteristics such as high speed response, powerful effects on the elimination of flatness defects such as edge-waves, central waves and so on. The existing research on flatness control mainly focuses on the calculation of optimal adjustment of individual flatness actuator. However, the final output of a flatness actuator is required to be limited firstly for some special cases. If the incoming strip is coming with big symmetrical flatness defects, it happens that the position limit of work roll bending is prone to be reached or exceeded during the execution of the displacement, resulting in the residual symmetrical flatness defects without further elimination, as well as a limited flatness control process. In order to avoid this situation, substitution control by intermediate roll bending in case of work roll bending control over-limitation have been developed, which is based on actuator efficiencies and in accordance with the practical conditions. Applications show that the substitution control of intermediate roll bending for work roll bending over-limitation can play an important role in the residually symmetrical flatness control.

Analysis of Actuator Performance Based on Actuator Efficiency in Flatness Control of Cold Rolling Mill

In order to improve the flatness of cold rolled strips, the accurate knowledge of actuator performance in flatness control is required. As the basis of flatness control, efficiencies of flatness actuators provide a quantitative description to the law of flatness control. In this paper, a 1250 single stand 6-H reversible UCM cold mill was taken as the object of this study, with efficiency factors of individual actuators analyzed for better flatness control. For the purpose of obtaining accurate efficiency factors matrixes of actuators, a self-learning determination model of actuator efficiency factors was established in accordance with the practical rolling processes. The actuator efficiency factors can be determined and improved continuously by the self-learning model with correlative measurement flatness data input. With this study, performance of actuators in flatness control of UCM cold rolling mill has been obtained, which provides a theoretical basis for better flatness control.

Performance Analysis of Asymmetrical Roll Bending for Flatness Control of Cold Rolling Mill

When there appeared catastrophic asymmetrical flatness defects in rolling processes, especially when the incoming strip is with a wedge shape, the tilting roll can hardly eliminate these defects completely. Moreover, the overshooting of tilting roll will lead to strip break. In order to improve the ability of cold rolling mill for asymmetrical flatness defects control, performance of the work roll asymmetrical bending as well as the intermediate roll asymmetrical bending has been analyzed, based on the actuator efficiency factors of them. In addition, for the purpose of obtaining accurate efficiency factors matrixes of actuators, a self-learning determination model of actuator efficiency factors was established in accordance with the practical rolling processes. In this paper, a 1250 single stand 6-H reversible UCM cold mill was taken as the object of this study, with efficiency factors of asymmetrical roll bending analyzed, which provides a theoretical basis for better flatness control. Analysis shows that the asymmetrical roll bending is significant for asymmetrical flatness control.

A Flatness Control System Design Based on Actuator Efficiency Factors for Cold Rolling Mill

In order to improve the flatness of cold rolled strips, strategies of closed loop feedback flatness control and rolling force feed forward control were established respectively, based on actuator efficiency factors. As the basis of flatness control system, efficiencies of flatness actuators provide a quantitative description to the law of flatness control. For the purpose of obtaining accurate efficiency factors matrixes of actuators, a self-learning model of actuator efficiency factors was established. The precision of actuator efficiency factors could be improved continuously by correlative measurement flatness data inputs. Meanwhile, the self-learning model of actuator efficiency factors permits the application of this flatness control for all possible types of actuators and every stand type. The developed flatness control system has been applied to a 1250mm single stand 6-H reversible UCM cold mill. Applications show that the flatness control system based on actuator efficiency factors is capable to obtain good flatness.

Carbon Nanotubes: High Electromechanical Response of Ionic Polymer Actuators with Controlled‐Morphology Aligned Carbon Nanotube/Nafion Nanocomposite Electrodes (Adv. Funct. Mater. 19/2010)

AbstractRecent advances in fabricating controlled‐morphology vertically aligned carbon nanotubes (VA‐CNTs) with ultrahigh volume fraction create unique opportunities for markedly improving the electromechanical performance of ionic polymer conductor network composite (IPCNC) actuators. Continuous paths through inter‐VA‐CNT channels allow fast ion transport, and high electrical conduction of the aligned CNTs in the composite electrodes lead to fast device actuation speed (>10% strain/second). One critical issue in developing advanced actuator materials is how to suppress the strain that does not contribute to the actuation (unwanted strain) thereby reducing actuation efficiency. Here, experiments demonstrate that the VA‐CNTs give an anisotropic elastic response in the composite electrodes, which suppresses the unwanted strain and markedly enhances the actuation strain (>8% strain under 4 V). The results reported here suggest pathways for optimizing the electrode morphology in IPCNCs using ultrahigh volume fraction VA‐CNTs to further enhanced performance.

Comb-Actuated Resonant Torsional Microscanner With Mechanical Amplification

A comb-actuated torsional microscanner is developed for high-resolution laser-scanning display systems. Typical torsional comb-drive scanners have fingers placed around the perimeter of the scanning mirror. In contrast, the structure in this paper uses cascaded frames, where the comb fingers are placed on an outer drive frame, and the motion is transferred to the inner mirror frame with a mechanical gain. The structure works only in resonant mode without requiring any offset in the comb fingers, keeping the silicon-on-insulator-based process quite simple. The design intent is to improve actuator efficiency by removing the high-drag fingers from the high-velocity scanning mirror. Placing them on the lower velocity drive frame reduces their contribution to the damping torque. Furthermore, placement on the drive frame allows an increase of the number of fingers and their capacity to impart torque. The microscanner exhibits a parametric response, and as such, the maximum deflection is found when actuated at twice its natural frequency. Analytical formulas are given for the coupled-mode equations and frame deflections. A simple formula is derived for the mechanical-gain factor. For a 1-mm × 1.5-mm oblong scanning mirror, a 76° total optical scan angle is achieved at 21.8 kHz with 196-V peak-to-peak excitation voltages.

Enhancing PKM Accuracy by Separating Actuation and Measurement: A 3DOF Case Study

This paper proposes an approach for enhancing parallel kinematics machine accuracy by separating actuation and measurement. We describe the interest of the separation actuation and measurement concept and define the sensor redundancy used for designing the measurement device. Then, we present the design of a parallel machine-tool prototype with an independent measuring system, MoM3, as well as the optimization of its measuring system. Lastly, we present the control schemes used on the prototype, and provide experimental results to show the efficiency of separation actuation and measurement applied to a machine-tool.

High Electromechanical Response of Ionic Polymer Actuators with Controlled‐Morphology Aligned Carbon Nanotube/Nafion Nanocomposite Electrodes

Recent advances in fabricating controlled-morphology vertically aligned carbon nanotubes (VA-CNTs) with ultrahigh volume fraction create unique opportunities for markedly improving the electromechanical performance of ionic polymer conductor network composite (IPCNC) actuators. Continuous paths through inter-VA-CNT channels allow fast ion transport, and high electrical conduction of the aligned CNTs in the composite electrodes lead to fast device actuation speed (>10% strain/second). One critical issue in developing advanced actuator materials is how to suppress the strain that does not contribute to the actuation (unwanted strain) thereby reducing actuation efficiency. Here our experiments demonstrate that the VA-CNTs give an anisotropic elastic response in the composite electrodes, which suppresses the unwanted strain and markedly enhances the actuation strain (>8% strain under 4 volts). The results reported here suggest pathways for optimizing the electrode morphology in IPCNCs using ultra-high volume fraction VA-CNTs to further enhanced performance.

Line-Focus Array Transducers for Effective Actuation of Tissue

Acoustic radiation forces induced by ultrasound can be used to apply external forces to an object, and the viscoelastic property of the object can be evaluated by measuring the resultant regional displacement of the object using a different ultrasonic probe for measurement. However, according to safety guidelines for the use of ultrasound, the recommended intensity is below 1 W/cm2 for continuous waves. Therefore, to generate a measurable displacement or strain by acoustic actuation, a method of effectively applying acoustic radiation forces needs to be devised. A potential way to improve the efficiency of acoustic actuation is to use line-focus transducers. However, there are undesired fluctuations in the emitted sound field due to the finite aperture size with uniform apodization when a single-element line-focus transducer (SELFT) is used to emit plane waves, which are focused only in the elevational direction. To suppress such undesired fluctuations, in the present study, a pair of line-focus array transducers (LFATs) was constructed to realize spatially smoother radiation forces by applying an appropriate apodization. As a result, the three dominant undesired peaks in the sound field emitted from a SELFT were suppressed using the LFATs with the examined appropriate apodization, and the displacement distribution induced in a phantom, which was measured by the phased tracking method using the different ultrasonic probe, became spatially smooth.

Slider Design Optimization for Lube-Surfing Head-Disk Interface Scheme

The stringent magnetic spacing requirement of future high-density magnetic disk drives requires new head disk interface scheme. One possible approach is the lube-surfing scheme-where majority of the slider body is flying while the reader/writer (R/W) element is thermally protruded to contact and penetrate the disk lubricant. This scheme, however, has many challenges to overcome to be feasible. One of these challenges is a slider with improved disk waviness-following capability especially for waviness with wavelength less than half the slider length. This paper explores air bearing design strategies to improve the waviness-following performance of a Femto slider. We propose a ¿W-shaped¿ trailing pad slider and investigated the impact of pad layout, etching depth and trailing pad size to the disk waviness-following performance. We have also incorporated a trenched trailing pad structure to reduce air bearing pressure over the R/W element so as to minimize the loss in air bearing pressure during lube contact and to improve the actuation efficiency.

Active structural acoustic control for a truck oil pan: Actuator placement and efficiency estimation

The oil pan of large diesel engine trucks is identified as a significant contributor to their external noise radiation. This undesired broadband noise is caused by the oil pan's structural vibration and cannot be treated effectively by passive measures, especially in the low frequency range up to 500 Hz. In order to address this challenge, an Active Structural Acoustic Control (ASAC) system was to be realized within the European Union (EU) project �Intelligent Materials for Active Noise Reduction� for the oil pan of a Volvo MD13 truck engine. The technological demonstration was conducted in a laboratory test stand and employs piezoceramic patch actuators to alter the vibrations in a broadband noise reduction manner. The following paper focuses on the tasks of deriving actuator placement and estimating respective broadband sound power minimization capability. First, the oil pan's structural response to typical force excitation at its mounting points was analyzed through finite element simulation, and an actuator placement was derived. The estimation of its sound power minimization capability was then established based on computed structural frequency response functions and numerically derived radiation modes. Finally, the actuator layout was transferred to a serial production oil pan and adjusted by experimental observations

Light-Driven Actuator with Shape Memory Alloy for Manipulation of Macroscopic Objects

With the aim of manipulating macroscopic objects, the possibility of improving energy conversion efficiency of light-driven actuators (LDAs) was investigated. Thermal expansion is one of the most efficient mechanisms reported so far but a rough estimation revealed that its upper limit in efficiency is ∼10−4%. Thermodynamics suggests several percent can be achieved in theory, so by using a suitable mechanism there is room for improvement. Based on those considerations we propose a LDA using a pre-tensioned wire of shape memory alloy. This design reduces the energy loss in converting the input light into mechanical motion. We demonstrated that a force larger than 1 Newton and an energy conversion efficiency of 1 percent can be achieved.

Trenched Trailing Pad Air Bearing Surface Structure for Improved Thermal Actuation Efficiency

The thermally actuated flying height control (TFC) technology makes accurate flying height control possible. However, one concern is how to have a proper balance between flying height stability and thermal actuation efficiency, as high air-bearing stiffness at the slider's trailing pad increases the flying height stability but reduces thermal actuation efficiency. A trenched trailing pad ABS structure is explored to solve the abovementioned dilemma. The effects of pad shape, trench depth, and width on the thermal actuation efficiency were investigated. Results indicate that the trenched trailing pad structure significantly improves the actuation efficiency as compared to the conventional ABS. The new structure also improves the ease of fabricating relatively small pad sizes by adopting a multiple etching process which allows the photoresist mask outline to be extended beyond the slider's ABS boundary to provide more footprint and stability to the photoresist pattern.

Electrothermal actuation of silicon carbide ring resonators

Silicon carbide (SiC) ring resonators have been designed, simulated, and fabricated in order to achieve higher resonant frequency compared to beam resonators. The resonant frequency as a function of the ring radius and central hole radius, as well as the influence of the electrode design on the actuation efficiency have been investigated. Aluminum (Al) electrodes have been fabricated on top of the structures in order to study the electrothermal actuation of the structures. The bimorph Al/SiC ring resonators have been constructed by etching the SiC in inductively coupled plasma. The release of the Si sacrificial layer has been performed with a XeF2 chemical etching. The radial release and area release have been characterized as a function of the central hole dimension at chamber pressure of 1 and 2 Torr, whereby the release rates have been found to increase as the hole dimensions and the etching pressure increases. In addition, the release process has shown to be governed by aperture effects. The rings fabricated with different dimensions have been actuated mechanically and electrothermally, and the resonant frequency detected optically. The resonant frequency has been shown to increase as the ring radius decreases and the hole radius increases, both theoretically and experimentally.