Modelo de interacción en entornos inmersivos de simulación mediante la integración de los sentidos de la vista y el tacto

Abstract

Haptic devices make it possible to perceive properties of virtual objects by means of the sense of touch. Based on the type of feedback they provide, a distinction can be made between haptic devices and force-feedback devices. Force feedback devices are considered the most realistic since they respond to the user’s interaction with the system and transmit object properties such as geometric shape, hardness and weight. To provide this feedback they must have mechanical links capable of acting on the end effector manipulated by the user. These mechanical links are the main limitation of these devices, since the available working space is always limited by the physical dimensions of the arms. This limitation makes necessary interaction techniques that allow the use of these devices to interact haptically with scenes of larger dimensions than those of their workspace. The literature review conducted identifies several techniques specifically designed to address this limitation. However, the review also evidences that none of them allow for easy integration of these devices into virtual reality experiences and that the uses that have been made of haptic devices in these immersive environments have featured limited interaction by not applying specific techniques. To provide a solution to the identified problem, a first interaction model called haptic zoom has been developed that addresses the problem of the limited workspace of forcefeedback desktop haptic devices. This model allows, through a continuous mapping of the device’s workspace and the area viewed by the user, both to move freely throughout the scene and to focus on an area of interest by performing a series of visual and haptic zooms. The results of the evaluation performed comparing the new technique with classical techniques shows that the new technique is as easy to use as direct mapping and offers as much accuracy as clutching. A second interaction model has been developed that focuses on enabling the use of force-feeback desktop haptic devices as the primary interaction mechanisms in virtual reality experiences. This new model is called haptic reality and its operation is based on defining a virtual representation of the device workspace called the action area. The technique allows haptic interaction with the elements inside the action area and, to provide the user with greater precision, it integrates the haptic zoom technique, which allows the size of the action area to be modified. In order to interact with objects outside the action area, the model includes a relocating mode that allows repositioning the action area anywhere in the scene. This technique has been implemented in the ParaVR medical simulator and has been tested by a set of emergency service paramedics from the Wales Ambulance Service NHS Trust, who rated both the simulator and the technique positively. Formal evaluation of the haptic reality technique has been carried out in a comparison with the bubble technique and the results have shown that the new technique is superior to the bubble technique in several respects, placing it as the benchmark technique when integrating force-feedback desktop haptic devices into immersive virtual reality experiences.