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Human Computer Interaction

Specification of the Haptic Elements in Proposed Design

Haptic refers to nonverbal communication, which involves the sense of touch. The proposed design will be implemented in a manner that will be possible for the user to interact with the system using only the sense of touch. This will require that the system sends feedback to the user through the user of vibration, forces and/or motions. The haptic feedbacks will be provided through the user's hands. The haptic system is able to detected movements coming from the environment, depending on this input, it responds by exerting force to the environment.

For the system to respond to the human actions and send appropriate responses to the human, it will be necessary to understand the working of the human sense of touch. It is necessary to ensure that haptic signals are perceived by the user correctly. This will require the haptic interface to be tuned to human sensitivity thresholds and limitations and calibrated appropriately.

During the design, it is necessary to note the various specifications that will enable the users to interact with the device. The dexterity of the device will determine the pressure to be applied by the user before the device registers this as a command. This specification will determine the pressure and motion necessary to accomplish a task. To determine the amount of pressure that the device will detect as a command, it will be necessary to use calibration. This will determine the amount of pressure to which the device will respond. This can be accomplished by use of tactile sensors. These sensors will assist in measuring the force applied on the device by the user.

Another specification will be the behavior of a depressed key. This will specify the amount of pressure to be exerted on a key for the system to register it as a human action. It will also be necessary to specify the switch de-bounce, this specifies the amount of time that a key may be pressed without registering double input (Burdea, 1996).

The proposed design will be able to give some virtual response to the user. This can be accomplished by making the color of a button to change once a key has been pressed and registered successfully. After the haptic is applied, the haptic devices, using the actuators, will apply a force to the user's skin to provide feedback. For example, when opening a slider cell phone, the screen changes color when touched. Touching and moving the slider to open the cell phone results to a vibration. The texture of a screen of such a slider cell phone is smooth to the touch. The haptic device will have a hard but smooth texture to enable easy handling. The smooth texture will help register the touch from the user. Specifications such as detection threshold are also important in the proposed design. This will be affected by factors such as nature of the haptic device and the size of the icon.

Physical Requirements by the User

Rotational Movements

Since the device is hand-held, the user will require some rotational movements to effectively use the interface. Rotational movements of the head of a human being enable the head to nod up and down giving a yes signal. Depending on height at which it is held, the user may move the head to be able to view the device. Other rotational movements such as rotation of the head from side to side will also help in locating the position where the device is held (Burdea, 1996).

Translational Movements

The device may be held in closely to the face of the user, this way; the user can just maintain the normal posture while interacting with the interface of the device. If the device is located further from the face of the user, the user will require some translational movements. The movements will make it for the user to have a better view of the screen. This is made possible by the ability of the neck to move the head along the X axis. The user will also be required to use the parallelity concept while viewing the content on the screen of the device. Attempt to view the screen content from either will not be possible. The device can be designed to detect the posture of the user using the parallelity concept, the device will detect when the user is in a diagonal posture and change the orientation of the screen accordingly (Burdea, 1996).

Accommodating Users with Limited Physical Abilities

The device will have capabilities to accommodate users with limited physical abilities such as arthritis or inability to apply a lot of pressure to the button. For the individual who are not able to apply much pressure to the button, the device can be configured to register an instruction after exerting the maximum pressure as per the ability of the user. Users suffering from arthritis may not be able to exert pressure on the buttons as a result of the painful joints caused by the disease. Users having these limited physical abilities may also have problems interpreting the response from the system. This requires that a device intended to be used by such persons be set to detect the amount of pressure that the person can exert, and also the system should provide feedback according to what the user can be able to interpret correctly. This will require that the haptic interface are calibrated depending on the relative receptivity of the skin of each user (McLaughlin, Hespanha, & Sukhatme, 2002).

The calibration should be customized according to the needs of the individual because pressure limits are not the same for every person. Pressure limits depends on the age, gender, and body location. Also, the device should have rapid adaptation receptors that will be continuously stimulated to develop a sense of touch depending on the ability of a user.