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Abeykoon, A. M. Harsha S.; Ohnishi, Kouhei
doi: 10.1163/156855308X314506pmid: N/A
Interest in tele-operation started many decades ago. Today, tele-operation is becoming a reality with improved tele-communication systems. Bilateral control is also a subset of tele-operation. Usually in bilateral control, force position information is exchanged between a master and a slave. This structure successfully transmits tactile sensation from the slave environment to the master operator. A bilateral control system is capable of transmitting tactile sensation to the master side. This capability is also known as the transparency of the system. If bilateral control is used in a surgery, ideally the medical doctor should sense the feeling coming from the body tissue together with the reaction force of the special surgical tool. We have previously proposed a method to eliminate the special surgical tool with a simple tool tip and a virtual tool model. However, a physical tool as well as the proposed virtual tool add impedance to the system. Even if a virtual model is used, impedances are essential to carry out the tool action. In this paper, a novel method is proposed to switch off and on the virtual tool model when the tool action can be replaced by the environmental reaction forces. An experiment was carried out using a bilaterally controlled forceps robot. Results show the applicability of the idea.
Kim, Yeongmi; Oakley, Ian; Ryu, Jeha
doi: 10.1163/156855308X314524pmid: N/A
The ability to combine tactile, on-the-skin, sensory cues with the kinesthetic ones that widely available force-feedback devices are able to produce is a desirable one, opening the door to the production of more realistic, compelling virtual environments. Pneumatic air-jet displays can be easily mounted on existing force-feedback devices and we believe have the potential to provide useful complimentary tactile information. However, there is little concrete psychophysical data relating to pneumatic displays — a fact that hinders their adoption. This paper addresses this challenge, and presents brief psychophysical studies examining localization rate, the two-point threshold and the stimulus intensity of cues produced by pneumatic air jets. Using insights gained from these studies, we also present a more concrete application-focused investigation where we evaluate the effect of combining tactile and force-feedback cues in a simple object manipulation task in a virtual environment. We show that task completion times are significantly improved with the addition of tactile information, validating our ideas and suggesting this topic warrants further attention.
Wettels, Nicholas; Santos, Veronica J.; Johansson, Roland S.; Loeb, Gerald E.
doi: 10.1163/156855308X314533pmid: N/A
The performance of robotic and prosthetic hands in unstructured environments is severely limited by their having little or no tactile information compared to the rich tactile feedback of the human hand. We are developing a novel, robust tactile sensor array that mimics the mechanical properties and distributed touch receptors of the human fingertip. It consists of a rigid core surrounded by a weakly conductive fluid contained within an elastomeric skin. The sensor uses the deformable properties of the finger pad as part of the transduction process. Multiple electrodes are mounted on the surface of the rigid core and connected to impedance-measuring circuitry safely embedded within the core. External forces deform the fluid path around the electrodes, resulting in a distributed pattern of impedance changes containing information about those forces and the objects that applied them. Here we describe means to optimize the dynamic range of individual electrode sensors by texturing the inner surface of the silicone skin. Forces ranging from 0.1 to 30 N produced impedances ranging from 5 to 1000 kΩ. Spatial resolution (below 2 mm) and frequency response (above 50 Hz) appeared to be limited only by the viscoelastic properties of the silicone elastomeric skin.
doi: 10.1163/156855308X314542pmid: N/A
This paper proposes a tactile display mouse providing both pin-array-type tactile feedback and thermal feedback. The pin-array-type tactile display is composed of a 6 × 5 pin-array that is actuated by 30 piezo-electric bimorphs. Micro shape and vibrotactile feedback can be generated by the device, and various planar distributed patterns can be displayed as can Braille cell patterns. The thermal feedback device is composed of a thin-film resistance temperature detector, a Peltier thermoelectric heat pump and a water cooling jacket. Users can discriminate among different materials by considering the temperature variation that can be sensed as they touch an object's surface. This paper also includes an experimental evaluation of the tactile display mouse to prove the effectiveness of displaying textures. Evaluation of the ability to identify material properties was conducted using the thermal feedback part that displays a simulated temperature profile. To investigate thermo–tactile interaction, an experiment determining perceived magnitude of vibrotactile stimulus according to different temperature conditions was conducted.
Suwanratchatamanee, Kitti; Matsumoto, Mitsuharu; Hashimoto, Shuji
doi: 10.1163/156855308X314551pmid: N/A
This paper presents a new tactile sensor system and an active sensing technique to realize active object surface sensing. Experimental results are also presented. The tactile sensor unit implemented on the robot hand consists of three force-sensitive resistors arranged triangularly. The unit can detect not only the reactive force from the object, but also determine the orientation of the object surface. Three possible applications are introduced. The first application is three-dimensional (3-D) object edge tracing, which can be employed in industrial processes such as welding and inspection to eliminate manual teaching procedures. The second application is the control of a hand pose to keep the direction of the hand normal to the object surface in 3-D, which is often necessary when pushing an object. Third is the realization of effective human–robot cooperation to move an object together.
Tamei, Tomoya; Ishii, Shin; Shibata, Tomohiro
doi: 10.1163/156855308X314560pmid: N/A
This study proposes a new approach to virtual realization of force/tactile sensors in machines equipped with no real sensors. The key of our approach is that a machine exploits the user's biological signals. Therefore, this approach is not dependent on controlled objects and is expected to be widely applicable for a variety of machines including robots. This article describes an example robotic system comprised of an industrial robot manipulator, a motion capture system and a surface electromyogram (EMG) measurement apparatus. By monitoring/recording the user's surface EMG and postural information in real-time, we show that a robot equipped with no force/tactile sensors behaved similarly to one possessing sensors over its body. Another advantage of our approach is demonstrated by a task in which a robot and a user cooperatively hold and move a heavy load.
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