Computer graphics processing and selective visual display system – Display peripheral interface input device
Reexamination Certificate
1997-01-17
2001-10-30
Wu, Xiao (Department: 2674)
Computer graphics processing and selective visual display system
Display peripheral interface input device
C345S157000
Reexamination Certificate
active
06310604
ABSTRACT:
TECHNICAL FIELD
The present invention relates to virtual reality and telereality employed in various fields such as design, education, training, amusement, hazardous operation, micromanipulation/supermicromanipulation, and more particularly to virtual reality system and telereality system which display to an operator, in real time, force senses in a virtual world created by a computer or in a telereal world which actually exists, by using control mechanism that electrically varies flow resistance of an electrorheological fluid.
The virtual reality system and telereality system in accordance with the present invention are also utilized as a haptic interface that displays information perceived by a motor-sensory system, that is, information associated with mechanical force senses involved in body movement.
TERMINOLOGY
The term “virtual reality” in the present invention refers to a world of images such as computer graphics created on a display by a computer. The images may be formed on any of a CRT, screen, flat display, and 3D (3-dimensional) display. Although the images formed on the visual display are synchronized in real time with the flow resistance of the electrorheological fluid in a force display device as in the telereal world, real force effect is not involved as in the telereal world. The term “real time” in the present invention refers to a fact that no substantial delay is present although a very short delay is allowed in image processing, or electrical or mechanical transmission.
The term “telereal world” in the present invention refers to a world in which mechanical forces are exerted such as operations in extreme environments in various fields like nuclear power, sea, disaster prevention, or space, or micromanipulation/supermicromanipulation in various fields like medical treatment, electronic components, micro-machining. In other words, it is a telereal world in which mechanical forces are exerted by the operator of the force display system via a mechanical medium such as a robot or manipulator, and a real world in which, are exerted the same mechanical or physical laws as in the world the operator is present. Therefore, the world in which the operator of the force display system is present is synchronized with the telereal world in which the mechanical forces are exerted are performed in real time.
The term “virtual reality system” in the present invention refers to a system that provides an operator with real time telepresence as if he or she were present, and acted or worked in the virtual world created by a computer. Although conventional systems mainly appeal to the eye and/or ear, the system in accordance with the present invention appeals to force senses, as well.
The term “telereality system” in the present invention refers to a system that provides an operator with real time telepresence as if he or she experienced events in a unique real world such as extremely fine, hazardous, or bad environment through a mechanical medium like a robot, thereby appealing with real time presence to the various senses of the operator, particularly to the force senses.
The term “teleexistence system” in the present invention includes both the virtual reality system and the telereality system.
The term “force sense” refers to a tactile or bodily sensation, that is, senses accompanying the movement of man's hands and feet, or actions on external objects. The tactile sensation includes senses such as soft, hard, heavy, light, strong, elastic or viscous associated with actions such as push, pull, touch, grasp, turn, hit, or kick, and the bodily sensation includes similar senses involved in actions such as press, draw, or tightening.
The term “force display device” refers to a device implemented in the form of gloves, fingers, arms, grips or elbows, which are analogous to man's counterparts. The force display device in accordance with the present invention which utilizes electrorheological fluid can be implemented by simpler and more compact structure than the conventional purely mechanical device.
The term “mechanical variables” refers to variables such as position, angle, distortion amount, velocity, force, pressure, acceleration. Sensors for detecting these variables are generally mounted on the force display device. They are often mounted on the output system which performs mechanical operation in the telereal world.
The term “electrorheological fluid” refers to fluid whose viscosity changes instantaneously and reversibly when electric field is applied thereto, and is roughly divided into dispersion electrorheological fluid and homogeneous electrorheological fluid. The dispersion electrorheological fluid is formed by dispersing dielectric particles into insulating oil, whereas the homogeneous electrorheological fluid does not use particles. The dispersion electrorheological fluid employs particles such as:
(1) Inorganic particles.
Silica or zeolite containing ionically polarizable water, acid or alkali, or organic electrolyte.
(2) Organic particles.
Ion exchange resin, or cellulose.
(3) Semiconductor particles.
Carbon or polyaniline or metallo phthalocyanine which contains no water and causes electronic polarization rather than ionic polarization.
(4) Metal particles or electroconductive polymer particles having insulating thin films coated on their surfaces.
(5) Particles composed of materials with conductivity anisotropy and nonlinear optical characteristic.
Besides, the following insulating oils are generally used which are stable in electric insulation, in addition to stable mechanical, physical and chemical characteristics: for example, silicone oil, fluorocarbon oil, mineral oil, paraffin, aromatic ester oil, aliphatic cyclic compound ester oil, natural oil.
On the other hand, as the homogeneous electrorheological fluid, it is preferable to use materials or their solution with such properties as liquid crystal, viscosity anisotropy, amphiphilic, ferroelectricity, and high dipole moment. In particular, liquid crystal, especially liquid crystalline polymer is preferable.
The dispersion electrorheological fluid generally exhibits Bingham fluid characteristic in which the shear stress is nearly constant independently of the shear velocity when electric field is applied. On the other hand, the homogeneous electrorheological fluid generally shows so-called Newtonian Flow characteristic in which the shear stress is proportional to the shear velocity.
BACKGROUND ART
The virtual reality or teleexistence technology flourishes which provides real time telepresence where we have the illusion that we are really present and work in the virtual reality created by a computer or in the telereal world which actually exists in a very fine or hazardous environment. To make a human operator feel as if he or she were in that place, a high performance force display device is essential. In addition, it is necessary to conduct wide spectrum of research on the entire systems including sensors, actuators, and computer systems associated with the force display devices.
The following techniques are reported on the force display device used in the virtual reality system.
(1) M. Minsky, et al. disclose in ACM SIGGRAPH, Vol. 24,235, 1990, a “virtual sandpaper” that provides fingers with the surface texture of a virtual object. It has a sensor for detecting positions in all movable directions, and expresses texture by resistance created by a special big joy stick including motors and brakes, each of which is mounted on each shaft of the joy stick, thereby providing a hand with the surface texture of the virtual object.
(2) Iwata, et al. disclose in ACM SIGGRAPH, vol. 24,165, 1990, a device that provides operator's fingers and hand with force senses through a special disk top manipulator when he or she touches a virtual object. The disk top manipulator has a configuration with many small, metal pantograph arranged ingeniously, and provides the force which is generated by a mechanism including motors to fingertips inserted thereto.
(3) Hashimoto, et al. disclose in Journal of the Robot
Furusho Junji
Inoue Akio
Sano Akihito
Asahi Kasei Kabushiki Kaisha
Finnegan Henderson Farabow Garrett & Dunner L.L.P.
Wu Xiao
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