Virtual Reality and Assistive Technologies: A Survey <s> IV. HAPTIC VIRTUAL ENVIRONMENTS <s> Data visualization is a technique used to explore real or simulated data by representing it in a form more suitable for comprehension. This form is usually visual since vision provides a means to perceive large quantities of spatial information quickly. However, people who are blind or visually impaired must rely on other senses to accomplish this perception. Haptic interface technology makes digital information tangible, which can provide an additional medium for data exploration and analysis. Unfortunately, the amount of information that can be perceived through a haptic interface is considerably less than that which can be perceived through vision, so a haptic environment must be enhanced to aid the comprehension of the display. This enhancement includes speech output and the addition of object properties such as friction and texture. Textures are generated which can be modified according to a characteristic or property of the object to which it is applied. For example, textures can be used as an analog to color in graphical displays to highlight variations in data. Taking all of these factors into account, methods for representing various forms of data are presented here with the goal of providing a haptic visualization system without the need for a visual component. The data forms considered include one-, two-, and three-dimensional (1-D, 2-D, and 3-D) data which can be rendered using points, lines, surfaces, or vector fields similar to traditional graphical displays. The end result is a system for the haptic display of these common data sets which is accessible for people with visual impairments. <s> BIB001 </s> Virtual Reality and Assistive Technologies: A Survey <s> IV. HAPTIC VIRTUAL ENVIRONMENTS <s> The recent addition of force and touch feedback to virtual reality simulations has enhanced their realism. Research on haptics interfaces is now extended to physical modeling of contact surfaces, object hardness, surface deformation, etc. This is especially needed when dextrous manipulation of virtual objects is concerned. The paper describes a VR system using a haptic glove (Rutgels Master II) connected to a PC workstation, and a new method for modeling virtual hand haptic interactions. An application example presented here is an orthopedic rehabilitation library. The exercises in this library involve interactions with dynamic objects and physical modeling of plasticity. <s> BIB002 </s> Virtual Reality and Assistive Technologies: A Survey <s> IV. HAPTIC VIRTUAL ENVIRONMENTS <s> A personal computer (PC)-based desktop virtual reality (VR) system was developed for rehabilitating hand function in stroke patients. The system uses two input devices, a CyberGlove and a Rutgers Master II-ND (RMII) force feedback glove, allowing user interaction with a virtual environment. This consists of four rehabilitation routines, each designed to exercise one specific parameter of hand movement: range, speed, fractionation or strength. The use of performance-based target levels is designed to increase patient motivation and individualize exercise difficulty to a patient's current state. Pilot clinical trials have been performed using the above system combined with noncomputer tasks, such as pegboard insertion or tracing of 2D patterns. Three chronic stroke patients used this rehabilitation protocol daily for two weeks. Objective measurements showed that each patient showed improvement on most of the hand parameters over the course of the training. Subjective evaluation by the patients was also positive. This technical report focuses on this newly developed technology for VR rehabilitation. <s> BIB003 </s> Virtual Reality and Assistive Technologies: A Survey <s> IV. HAPTIC VIRTUAL ENVIRONMENTS <s> Attention deficits are one of the most profound problems facing the traumatic brain injured individual. The Traumatic Brain Injury (TBI) inpatient population in the rehabilitation unit is difficult to study with new technology because it is often very difficult to render and evaluate such interventions in the short time span when a patient is still in the hospital, even though that is precisely the time when clinical attentional therapy is considered most critical. We developed and performed a preliminary test of a haptic/graphic paradigm for improving attention and concentration in early stages of recovery in the TBI inpatient population. Six TBI patients and three healthy controls were exposed to a minimal distraction/minimal interaction environment while reaching for a visual target. Our initial results showed (1) the subjects tolerated the experience, (2) the number of targets acquired in successive one-minute intervals indicated a sustained attention for the task, and (3) haptic interaction in such an environment was well tolerated, engaging, and enjoyable -- often considered a game. These findings have provided the foundation for a larger, intensive, protracted study with repeated treatment. <s> BIB004 </s> Virtual Reality and Assistive Technologies: A Survey <s> IV. HAPTIC VIRTUAL ENVIRONMENTS <s> This paper presents the design and characteristics of a five-fingered haptic interface robot named HIRO III. The aim of the development of HIRO III is to provide a high-precision three-directional force at the five human fingertips. HIRO III consists of a 15-degrees-of-freedom (DOF) haptic hand, a 6-DOF interface arm, and a control system. The haptic interface, which consists of a robot arm and hand, can be used in a large workspace and can provide multipoint contact between the user and a virtual environment. However, the following problems peculiar to a multi-DOF robot have arisen: a large amount of friction, a backlash, and the presence of many wires for many motors and sensors. To solve these problems, a new mechanism and a wire-saving control system have been designed and developed. Furthermore, several experiments have been carried out to investigate the performance of HIRO III. These results show the high-precision force display and great potential of HIRO III. <s> BIB005
Haptic relates to the perception using the sense of touch. Perception can be tactile or kinesthetic/ proprioceptive BIB001 . Tactile perception generates some kind of sensation to the skin; it is unidirectional. Kinesthetic /proprioceptive perception is bi-directional; users move their hands to reach for objects and resistive force is generated to the hand as the object is touched or grasped. Thus kinesthesis is the human sense of position and movement, which is created from proprioceptive cues arising from receptors in the joints and muscles (?; ?). A force feedback based haptic VE can extend a patients muscle capabilities by following the movement of the limb and producing external forces proportional to the forces applied by them BIB003  . To the blind and visually impaired, touch works as a substitute for vision. A haptic VE has also been successfully used to address attention deficiencies  BIB004 ). Force feedback-based haptic devices can be classified into the following two categories: (a) end effector and (b) exoskeleton. End effectors are non-exoskeletal devices. Some popular end effectors are 3D Systems Touch or Touch X, Novint Technologies Novint Falcon and more. On the other hand, exoskeleton haptic devices provide structural support to the patients paretic limb to further assist in its movement. Among the exoskeleton devices, Rutgers Master II-ND (RMII), CyberGrasp and Haptic Interaction Robot (HIRO) are widely used. Table 3 summarizes the classification of haptic VEs for different types of rehabilitation using different haptic devices. Among different haptic devices, end effectors are grounded and free standing; users commonly interact with VEs by gripping the handle of the device attached to the end of the device. Figure 8a and Figure 8b demonstrate 3D Systems two such end effectors known as Touch and Touch X respectively which are widely used for the rehabilitation of wrist and upper limbs. These are 3 degrees of freedom (DOF) force feedback haptic devices with 3D touch workspace and are capable of exerting force up to 3.3 Newton along X, Y and Z directions. 3D Systems Phantom Premium 6 DOF haptic devices are able to produce a larger amount of force and have a much larger work space than Touch devices to consider the movement of the whole arm. In addition to exerting force along X, Y and Z directions, 6 DOF devices are able to apply torque around X, Y and Z axes. The Novint Falcon is a 3 DOF haptic device that was originally designed for the gaming industry by Novint Technologies ( Figure 8c ). The arm of this device can extend, retract, and fold to measure range of motion. Mirror-image motion enabler (MIME) and HapticMaster are two widely used end effectors specifically designed for motor rehabilitation. MIME can work in bilateral mode, i.e., mirror image movements of the non-affected arm are sent to the robot to guide the movements of the paretic arm (Lum et In comparison with the end effectors, exoskeleton devices can be (i) ungrounded or (ii) grounded. Ungrounded exoskeletal devices are not free standing. Rutgers Master II-ND (RMII) as shown in Figure 9a is a light weight exoskeletal ungrounded robotic device and is used in conjunction with CyberGlove to track finger movements and provide force feedback to the fingers and hand BIB002 BIB003  . The force feedback on fingers is provided by the attached actuators to facilitate grasping or other activities in VEs. Cyber-Glove Systems CyberGrasp as shown in Figure 9b is another ungrounded exoskeletal device that works in a very similar way as RMII, but a bit heavier. The major structural difference between RMII and CyberGrasp is the placement of actuators. In a CyberGrasp system, actuators are placed on the dorsal side while actuators are placed inside the palm in RMII preventing full closure of the hand. Grounded exoskeleton devices are large and stationary and can be associated with a large and varied amount of force. These devices provide an orthotic shell to support the entire limb. Hand Wrist Assisting Robotic Device (HWARD), ARMin, and MAHI Exo-II are some popular grounded exoskeletons widely used for rehabilitation  HWARD and MAHI Exo-II can work both in active and passive modes. In passive mode, the robot moves the patients arm, unlike in the active assisted mode where the patient moves their arm with the help of the device to reach the desired target. Haptic Interaction Robot (HIRO) III as shown in Figure  9c is another grounded multi-fingered exoskeleton haptic interface that provides supports for all fingers to interact with the VE BIB005 ). HIRO III consists of a 15 DOF haptic hand (3 DOF for each joint in each finger), a 6 DOF interface arm, and a control system. It is placed against a human hand, and the haptic fingertips are connected to the human fingertips through passive spherical magnet joints. The rest of this section briefly discusses different types of haptics-based VR rehabilitation systems developed with the help of the haptic devices as mentioned in Table 3 for different types of impairments, i.e., mobility, cognitive, and visual.