Dongbum Pyo

A new subminiature impact actuator for mobile devices

This paper presents a new subminiature impact type actuator which creates the haptic sensation in a mobile device. Recently, linear resonance actuators (LRA) are widely used. One of the key differences between an LRA and a traditional eccentric motor is that the LRA generates the vibrotactile sensation through resonance for minimizing response time. The strategy of operation near the resonant frequency, however, brought a new issue for creating vibrotactile sensation which can be strong enough to feel in arbitrary frequency. In order to achieve this issue, we adopt an unstable structure to amplify impact force and to reduce response rate. Due to the impact with fast rising and falling time in the proposed impact actuator, the available strong impact vibration is created over wide frequency range from 0Hz to 100Hz. The impact vibration generated from the proposed actuator is suitable for reproducing realistic button sensation and creating various vibration patterns in mobile devices.

A New Surface Display for 3D Haptic Rendering

This paper presents a new surface display that enables realistic 3D haptic rendering with more plentiful haptic information. The visual feedback that is commonly provided from a touch surface includes depth and texture information. To render this information haptically, both kinesthetic feedback and tactile feedback are needed. Although electrovibration or mechanical vibration is currently used to simulate these types of feedback, it is not easy to render such complicated information by using only one of the two feedbacks. Also, in the case of electrovibration, active tactile feedback is not available because it can be conveyed only if the fingertip slides over the touch surface. To address these issues, we propose a surface display that can generate both electrovibration and mechanical vibration uniformly on a large surface. We describe the principle of operation and vibration characteristics of the system. A psychophysical experiment was then conducted to evaluate the effects of the mechanical vibration to the perceived friction force caused by electrovibration. Finally, we present the possibility of this approach as an effective method for 3D haptic rendering through several example applications.

Physical mobile interaction with kinesthetic feedback

As the gestural interface is emerging as one of the key interfaces for mobile computing, the ability of these interfaces to provide physical feedback is becoming more important. Especially in the context of interacting with a virtual world, generating proper feedback is more important when seeking to engage users in a simulated world. However, due to the inherent size problems of mechanical structures and due to power issues, most handheld devices relied on vibrotactile feedback. To resolve this issue, this paper proposes a haptic interface module that can represent realistic kinesthetic feedback for use with hand interfaces. Large-scale but slowly changing force is generated using a linear servomotor to provide general object information, such as the overall shape of an object. On the other hand, subtle haptic feedback generated by a solenoid-magnet pair provides the detailed surface properties of the object. To measure the performance of the proposed system, two experiments are conducted. From the experimental results, it was revealed that the proposed solenoid-magnet pair could generate about 1N of magnetic force. In terms of perception, the device can provide six levels of kinesthetic feedback. As an application, we propose depth-based interaction in which the proposed system is controlled by a depth-measuring unit.

Mechanical and psychophysical performance evaluation of a haptic actuator based on magnetorheological fluids

This study presents a miniature haptic actuator (10 mm (L) × 10 mm (W) × 6.5 mm (H)) based on magnetorheological fluids, which is designed to provide realistic touch sensations to users. Its primary goals are to evaluate mechanical or actuation performances of the prototype magnetorheological actuator and to assess its effectiveness in conveying haptic sensations to users by conducting the psychophysical experiments. The mechanical performance study evaluated the prototype’s output forces from haptic perspectives using a dynamic test frame. The psychophysical experiments studied human subjects’ perceptions on haptic sensations produced by the prototype. The mechanical test results show that the magnetorheological actuator is capable of generating a wide range of frequency-dependent output forces (from 1.5 N to nearly 9 N). The psychophysical experiments show that the actuator offers various kinesthetic and vibrotactile sensations to human operators. Overall, the results suggest a feasibility of using the magnetorheological haptic actuator in real-world applications, such as a haptic keypad and functional buttons in small consumer electronics and hand-held devices.

Design, simulation, and testing of a magnetorheological fluid–based haptic actuator for mobile applications:

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.

Development of an impact-resonant actuator for mobile devices

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 users 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.

Simultaneous Representation of Texture and Geometry on a Flat Touch Surface

We propose to combine two types of tactile feedback, electrovibration and mechanical vibration, for haptic interaction on a flat touch surface. This approach would enrich haptic effects for touch screen-based devices by simultaneously providing texture and geometry information.

Haptic Interaction on a Touch Surface

This paper presents a new surface display that enables delicate tactile rendering with electrovibration and mechanical vibration. Haptic information on the surface can be expressed more richly if both feedback types are rendered simultaneously.

Design and Simulation of an MR Fluids-Based Haptic Actuator for Mobile Applications

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

High-pressure endurable flexible tactile actuator based on microstructured dielectric elastomer

We demonstrate a robust flexible tactile actuator that is capable of working under high external pressures. The tactile actuator is based on a pyramidal microstructured dielectric elastomer layer inducing variation in both mechanical and dielectric properties. The vibrational performance of the actuator can be modulated by changing the geometric parameter of the microstructures. We evaluated the performance of the actuator under high-pressure loads up to 25 kPa, which is over the typical range of pressure applied when humans touch or manipulate objects. Due to the benefit of nonlinearity of the pyramidal structure, the actuator could maintain high mechanical output under various external pressures in the frequency range of 100–200 Hz, which is the most sensitive to vibration acceleration for human finger pads. The responses are not only fast, reversible, and highly durable under consecutive cyclic operations, but also large enough to impart perceivable vibrations for haptic feedback on practical wearable ...