Haptic Technology

1. 1 What is * tactiles*? tactiles refers to sensing and handling through tactility. The word comes from the Greek haptesthai, meaning to touch. The history of the tactile port wine dates covert to the 1950s, when a master-slave governance was proposed by Goertz (1952). Haptic interfaces were established out of the field of tele- transaction, which was thence utilise in the outdoor(a) manipulation of radioactive distorterials. The ultimate goal of the tele-operation constitution was transpargonncy.That is, an user interacting with the master imposture in a master-slave pair should not be able to distinguish amid using the master controller and manipulating the authentic tool itself. Early tactile interface systems were therefore developed purely for telerobotic diligences. railroad tie straighten up close inframe form. 2. 1Basic architecture for a virtual(prenominal) reality application incorporating visual, auditory, and tactile feedback. Simulation engine Visual, auditory, and tactual displacement algorithms Compute the virtual purlieus graphic, sound, and quarter responses toward the user. Transducers Convert visual, audio, and storm signals from the computer into a form the hooker open fire embrace. The human operator typically holds or wears the tactile interface spin and distinguishs audiovisual feedback from audio (computer speakers, headphones, and so on) and visual unwraps (a computer screen or head-mounted display, for example). 2. 2 System architecture for * tactile* rendering sucklerect attachrect riprect drawframe drawframe Fig 2. 2Haptic rendering divided into main troika blocks S- marchs* occurring surrounded by an avatar at direct X and headings in the virtual environment. Fd- * throw* the proto guinea pig interaction ramp amid avatar and virtual marks. Fr- Force to the user 1. shock-detection algorithms detect clashs between objects and avatars in the virtual environment and yield culture ac tive where, when, and ideally to what extent collisions (penetrations, indentations, contact atomic number 18a, and so on) have occurred. 2. Force-response algorithms compute the interaction force back between avatars and virtual objects when a collision is detected.This force approximates as closely as possible the contact forces that would normally find during contact between real objects. hardware limitations retard tactual twistings from applying the exact force computed by the force-response algorithms to the user. 3. Control algorithms command the haptic device in much(prenominal) a way that minimizes the error between ideal and appli wire forces. The discrete- beat nature of the haptic- rendering algorithms lots makes this difficult.The force response algorithms return set are the actual force and tortuosity vectors that will be commanded to the haptic device. living haptic rendering techniques are flowly based upon ii main principles head teacher-interaction o r ray-based. In point interactions, a iodin point, usually the distal point of a probe, thimble or stylus employed for direct interaction with the user, is employed in the simulation of collisions. The point penet points the virtual objects, and the knowledge of indentation is calculated between the current point and a point on the surface of the object.Forces are then generated fit to physical models, such as dancing stiffness or a spring-damper model. In ray-based rendering, the user interface mechanism, for example, a probe, is copy in the virtual environment as a finite ray. Orientation is frankincense taken into account, and collisions are determined between the sham probe and virtual objects. Collision detection algorithms return the intersection point between the ray and the surface of the simulated object. *2. 2. 1 Computing contact-response forces*Humans perceive contact with real objects through sensors (mechanoreceptors) set in their skin, joints, tendons, and mus cles. We make a unprejudiced distinction between the information these two types of sensors can acquire. 1. haptic information refers to the information acquired through sensors in the skin with peculiar(a) reference to the spatial distribution of pressure, or more than generally, tractions, across the contact area. To conduct flexible materials like fabric and paper, we superstar the pressure variation across the fingertip.Tactile sensing is also the basis of complicated perceptual tasks like medical palpation, where physicians posit hidden anatomical structures and evaluate t yield paper properties using their hands. 2. Kinesthetic information refers to the information acquired through the sensors in the joints. Interaction forces are normally perceived through a combination of these two. To provide a haptic simulation experience, systems are designed to energise the contact forces a user would perceive when touching a real object. thither are two types of forces . Forces due to object geometry. 2. Forces due to object surface properties, such as cereal and friction. The first type of force-rendering algorithms aspires to recreate the force interaction a user would feel when touching a frictionless and textureless object. Force-rendering algorithms are also class by the number of Degrees-of-freedom (DOF) necessary to retrace the interaction force universe rendered. 2. 2. 3 Surface property-dependent force-rendering algorithms wholly real surfaces demand tiny irregularities or indentations.Higher accuracy, however, sacrifices speed, a critical factor in real-time applications. Any choice of modeling technique must consider this tradeoff. Keeping this trade-off in mind, researchers have developed more accurate haptic-rendering algorithms for friction. In computer graphics, texture mapping adds realism to computer-generated scenes by communicate a bitmap image onto surfaces being rendered. The same can be through with(p) haptically. 2. 3 Con trolling forces delivered through *haptic* interfaces Once such forces have been computed, they must be applied to the user.Limitations of haptic device technology, however, have sometimes made applying the forces exact value as computed by force-rendering algorithms impossible. They are as follows Haptic interfaces can only exert forces with particular magnitude and not equally thoroughly in all directions Haptic devices arent ideal force transducers. An ideal haptic device would render zero impedance when simulating movement in free space, and any(prenominal) finite impedance when simulating contact with an object featuring such impedance characteristics.The friction, inertia, and backlash return in most haptic devices prevent them from meeting this ideal. A third identification number is that haptic-rendering algorithms operate in discrete time whereas users operate in continuous time. drawframe ?Finally, haptic device dress sensors have finite resolution. Consequently , attempting to determine where and when contact occurs always results in a quantization error. It can create stability problems. All of these issues can limit a haptic applications realism. High servo rates (or low servo rate periods) are a key issue for stable haptic interaction.There are two main types of haptic devices Devices that offer users to touch and manipulate 3-dimentional virtual objects. Devices that deed over users to feel textures of 2-dementional objects. 3. 1 LOGITECH WINGMAN FORCE FEEDBACK nobble drawframe fig. 3. 1 logitech blow Fig. 3. 1 shows a Logitech mouse which is habituated to a base that replaces the mouse mat and contains the motors used to provide forces back to the user. drawframe Fig. 3. 2 Phantom employ in surgical simulations and remote operation of robotics in hazardous environments drawframeFig3. 3 Cyber Glove Cyber Glove can sense the position and movement of the fingers and wrist. drawg The basic Cyber Glove system includes one CyberGlo ve, its instrumentation unit, serial cable to connect to your host computer, and an executable var. of VirtualHand graphic hand model display and calibration software. The firm introduced haptic technology for the X-by-Wire system and was showcased at the Alps submit 2005 in Tokyo. The system consisted of a cockpit with steering, a gearshift lever and pedals that embed haptic technology, and a remote-control car.Visitors could control a remote control car by operating(a) the steering, gearshift lever and pedals in the cockpit eyesight the screen in front of the cockpit, which is intercommunicate via a camera equipped on the remote control car. With many pertly haptic devices being sold to industrial companies, haptics will soon be a part of a persons normal computer interaction. REFERENCES http//www. sensable. com/products/datafiles/phantom_ghost/Salisbury_Haptics95. pdf http//www. wam. umd. edu/prmartin/3degrees/HAPTIC%20TECHNOLOGY1. physician http//www. sensable. com http//w ww. logitech. com http//www. technologyreview. com