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Pyo D.,KAIST | Yang T.-H.,Center for Mass and Related Quantities | Ryu S.,KAIST | Han B.-K.,KAIST | And 2 more authors.
Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) | Year: 2012

This paper presents a novel impact-resonant actuator (IRA) that can increase a degree of reality and a sense of immersion by providing a delicate haptic sensation. In current mobile devices, eccentric rotary motor and linear resonant actuators are widely used for haptic feedback, but they provide only simple vibration response to a user's on-screen touch. Varied vibration patterns cannot be generated due to their limited working frequency range. Also, it is hard to create crisp vibrotactile sensation which can mimic the sensation of pressing a button due to their slow response time and long residual vibration. To overcome the limitations of conventional actuators, the proposed actuator generates impact vibration, operating at a wide frequency range from 0 Hz to 190 Hz with a fast response time and very short residual vibration. Moreover, stronger impact force can be generated effectively near the resonant frequency. © 2012 Springer-Verlag. Source


Ryu S.,KAIST | Koo J.-H.,Miami University Ohio | Yang T.-H.,Center for Mass and Related Quantities | Pyo D.,KAIST | And 2 more authors.
Journal of Intelligent Material Systems and Structures | Year: 2015

This article presents a novel design of a miniature haptic actuator based on magnetorheological fluids for mobile applications with the aim of providing various haptic sensations to users in mobile devices. The primary design goal for a haptic actuator for mobile applications is to miniaturize its size while achieving large forces and low power consumption. To this end, this study proposes to design the actuator's piston head (or plunger) in cone shape and activate multiple modes of magnetorheological fluids. A prototype actuator was designed and fabricated based on a simulation model. Using a dynamic test frame, the performance of the prototype actuator was evaluated in terms of the force (resistive force) produced by the prototype. The results show that the small actuator (10 mm × 10 mm × 6.5 mm) produced a maximum resistive force of about 5 N and the force rate of nearly 80% at 0.3 W. This change in resistive force or the force rate is sufficient to provide several steps of force variation that is explicitly perceivable for operators, depending on the input power. The results demonstrate a feasibility of using the proposed actuator's applications in mobile devices, conveying realistic haptic sensations to users. © SAGE Publications. Source


Ryu S.,KAIST | Koo J.-H.,Miami University Ohio | Yang T.-H.,Center for Mass and Related Quantities | Pyo D.,KAIST | And 2 more authors.
ASME 2013 Conference on Smart Materials, Adaptive Structures and Intelligent Systems, SMASIS 2013 | Year: 2013

This study presents a novel design of a miniature haptic actuator based on Magneto-Rheological (MR) fluids for mobile applications, and it evaluates the performance of a haptic actuator using a simulation model. The primary design goal for a haptic actuator for mobile applications is to miniaturize its size while generating realistic haptic sensations. To this end, this study proposes to design the MR actuator's piston head (or plunger) in cone-shape and activate multiple modes of MR fluids (direct shear, flow and squeeze modes). Using a simulation model developed by integrating magnetic and force equations, the performance of a haptic actuator was evaluated in terms of the force (resistive force) produced by the actuator. The results show that a small actuator model, dimension of 10 mm (L) × 10 mm (W) × 6.5 mm (H), produced a maximum resistive force of about 5 N at 0.3 Watts, which is sufficient to provide force feedback to users. Copyright © 2013 by ASME. Source


Ryu S.,KAIST | Koo J.-H.,Miami University Ohio | Yang T.-H.,Center for Mass and Related Quantities | Pyo D.,KAIST | And 2 more authors.
ASME 2014 Conference on Smart Materials, Adaptive Structures and Intelligent Systems, SMASIS 2014 | Year: 2014

This paper presents design and testing of a haptic keypad system using an array of haptic actuators. The research goals are to construct a prototype haptic keypad system using haptic actuators and to evaluate the performance of the prototype keypad for haptic rendering. To this end, an MR haptic actuator was designed and fabricated such that it can convey realistic force feedback to users. To demonstrate haptic applications of the MR actuator, a haptic keypad system was constructed, which consists of following components: (1) 3 × 3 array of haptic actuators, (2) 3 × 3 array of force sensing resistors (FSR), (3) a controller including a micro-processor, a current amplifier and a wireless communication module, (4) a graphic display unit with PC. After constructing a prototype keypad system, a haptic rendering technology was employed to interface the hardware keypad system with test software (virtual environment). The prototype system enabled human operators to interact with the target contents in a virtual environment more intuitively. The evaluation results show a feasibility of applications of MR fluids-based haptic actuators in real-world mobile applications. © 2014 by ASME. Source


Pyo D.,KAIST | Yang T.-H.,Center for Mass and Related Quantities | Ryu S.,KAIST | Kwon D.-S.,KAIST
Sensors and Actuators, A: Physical | Year: 2015

In this study, a novel linear impact-resonant actuator was proposed for mobile device applications. The most significant issue in mobile haptic actuators is the ability to provide various vibrotactile and alert functions despite their size and power consumption limitations. This study aimed to achieve fast and strong impact vibrations over a wide frequency range, including the resonant frequency, which decoupled the intensity and frequency of the vibration to achieve both fruitful vibrotactile feedback and strong alarming vibration. To accomplish this, a new mechanism was proposed that can amplify the impact force at the end of the stroke and increase the speed of the response. The magnetic flux path was optimized using an equivalent magnetic circuit model to maximize the electromagnetic force. The performance of a prototype actuator (11 mm × 9 mm × 3.2 mm) was evaluated in terms of the response time and vibration acceleration amplitude under an input power of 0.3 W. The experimental results clearly showed that the proposed actuator could create a vibration acceleration that was greater than 2 g over a frequency range of 1-210 Hz with a fast response of 4 ms and extremely short residual vibration. In addition, a stronger impact force of around 3 g could be generated near the resonant frequency of 190 Hz. © 2015 Elsevier B.V. All rights reserved. Source

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