Fabrication and test of a micro electromagnetic actuator

Kim, Ki Hoon; Yoon, Hyeun Joong; Jeong, Ok Chan; Yang, Sang Sik

doi:10.1016/j.sna.2003.10.079

Cited by 54 publications

(47 citation statements)

References 10 publications

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“…Most of these are based on the electromagnetic working principles. Review of previously reported devices shows that they produce relatively small forces 14 mN [13], 6 mN [14], 0.9 mN [15], as a result of a trade-off between power and size of the actuator. More recent efforts to design smaller and more powerful actuators have led to devices based on moving permanent magnets with a diameter of 2 millimeters and a significant force peak (70.8 mN), however the force-displacement characteristic is monotonously decreasing thus making it difficult to remain in contact with the curved surface of the finger.…”

Section: Introductionmentioning

confidence: 99%

Development of Wearable Micro-actuator Array for 3-D Virtual Tactile Displays

Szabo¹,

Enikov²

2012

JEMAA

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A novel 4 by 4 array of electromagnetic micro-actuators operating on the principle of voice-coil actuators is presented. The intended application of the array is dynamic tactile stimulation, where multiple actuators generate an illusion of touching a moving pattern. In comparison to earlier designs [1-3], the device has smaller dimensions of 2.28 mm in diameter and 7 mm in length, which allowed its use in an array capable of hosting up to a 5 by 5 set of actuators with a rectangular shape covering an area of 18 mm by 21 mm. Using finite element analysis of several conceptual designs of actuators [1,4,5], it was established that the voice-coil type device (where the coil is the moving part) has most beneficial characteristics for the envisioned application. These include sufficient force over a relatively large distance, allowing tactile stimulation of surfaces with irregular shape, fast response, and small foot-print that matches the density of the tactile sensory neurons in the human finger. Eexperimental evaluation of the operation of neighboring actuators spaced at 3.3 mm apart, indicates that there is no crosstalk between the actuators. The resulting density exceeds that of previously reported alternative designs based on moveable permanent magnets [4,6]. Static force measurement indicate that each micro-actuator can produce at least 26 mN of repulsive force over a stroke of 2100 µm with a peak force of 34 mN. The driving circuit operates at 13.5V and generates a vibration frequency of up to 265 Hz without significant change of the force-displacement characteristics. In the higher frequency range (above 100 Hz) the actuator provides at least 15 mN of force over a slightly reduced stroke of 2300 µm, and a peak force of 21 mN. All of the above parameters meet the required threshold values of tactile human perception known from [2] and [3]

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Section: Introductionmentioning

confidence: 99%

Development of Wearable Micro-actuator Array for 3-D Virtual Tactile Displays

Szabo¹,

Enikov²

2012

JEMAA

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“…Characteristics of those actuation methods are compared in Table. 2. Electromagnetic method requires high power [12]. In the thermal method, the actuator part is heated to high temperature for deformation [13].…”

Section: Introductionmentioning

confidence: 99%

Wireless Driving of a Micromirror Device by Electoromagnetic Excitation Tuned to Mechanical Resonance of Rotation

Kumagai

Ohnishi

Sasaki

2012

JAMDSM

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Wireless driving of a micromirror device is achieved by electromagnetic excitation tuned to the mechanical resonance of the mirror rotation. The micromirror used is designed for low-voltage-driving. Static mirror rotation angle is 7.7 deg. at 12 V bias. The micromirror is connected to a coil for receiving the driving energy through electromagnetic induction. Magnetic field of 19.3 mT at the surface of the first coil induces 0.6 V at the second coil that is 24 mm apart from the first coil. An LC resonance circuit is incorporated in the second coil system to enhance the induced voltage. The LC resonance frequency is tuned to induce the mechanical resonance of the micromirror device. When the separation distance between the first and second coils is 24 mm, the voltage induced by the LC resonance is 1.43 V. Mirror rotation angle is 0.3 deg. for half stroke is achieved. It is expected that the rotation angle is expanded by increasing the Q factors of the electrical circuit and mechanical resonance of the micromirror. These will be achieved by reducing the loss in the electrical circuits and packaging the micromirror device in vacuum with hermetic seal.

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“…Also, there is an upper limit of about 50 Hz on the actuation frequency of this actuation method due to the long thermal time constant, especially during the cooling process. Electrostatically actuated diaphragms offer operation frequencies of several kHz, at extremely low power consumption and full micro system compatibility [11,17], but with an inherently small actuation stroke limited to a practical value of around 5 m with actuation voltages of around 200 V. Electromagnetic actuators have high field energy density and fast response time, and new technologies for fabricating magnetic microcoil elements have been incorporated in diaphragm pump designs [18]. The produced pumps exhibited large membranes deflection with low input voltage, and were able to self-priming, and to generate water flow rates up to 1 ml/min against a backpressure of 50 mbar [19].…”

Section: Introductionmentioning

confidence: 99%