Virtual Reality allow users to explore virtual environments naturally, by moving their head and body. However, the size of the environments they can explore is limited by real world constraints, such as the tracking technology or the physical space available. Existing techniques removing these limitations often break the metaphor of natural navigation in VR (e.g. steering techniques), involve control commands (e.g., teleporting) or hinder precise navigation (e.g., scaling user's displacements). This paper proposes NaviFields, which quantify the requirements for precise navigation of each point of the environment, allowing natural navigation within relevant areas, while scaling users' displacements when travelling across non-relevant spaces. This expands the size of the navigable space, retains the natural navigation metaphor and still allows for areas with precise control of the virtual head. We present a formal description of our NaviFields technique, which we compared against two alternative solutions (i.e., homogeneous scaling and natural navigation). Our results demonstrate our ability to cover larger spaces, introduce minimal disruption when travelling across bigger distances and improve very significantly the precise control of the viewpoint inside relevant areas.

This paper seeks to determine how the overlap of several infrared beams affects the tracked position of the user, depending on the angle of incidence of light, distance to the target, distance between sensors, and the number of capture devices used. We also try to show that under ideal conditions using several Kinect sensors increases the precision of the data collected. The results obtained can be used in the design of telerehabilitation environments in which several RGB-D cameras are needed to improve precision or increase the tracking range. A numerical analysis of the results is included and comparisons are made with the results of other studies. Finally, we describe a system that implements intelligent methods for the rehabilitation of patients based on the results of the tests carried out.

Abstract This paper proposes the use of RGB‐D sensors in motor rehabilitation of patients suffering acquired brain injury. Indeed, RGB‐D sensors are promising in their use as assistive technologies in ambient assisted living and rehabilitation places. The paper describes the system developed for creating and monitoring the ambient assisted environment for rehabilitation. The proposal consists of four major tasks: workspace configuration, information integration, user identification, and user tracking. Another main concern in this paper is to assess the user experience of the environment and scenario. A qualitative evaluation of the proposal has been performed to find out how the stakeholders of the proposed RGB‐D assistive technologies environment (injured patients and therapists) use and perceive the ambient assisted rehabilitation room.

Interaction is gradually moving from desktop computers to the open air thanks to depth sensors such as Kinect, Xtion and Leap Motion. In this new situation, in which the user is no longer holding any device, the simulation of the sense of touch is progressively gaining more interest. This paper describes how VITAKI, a VIbro Tactile prototyping tool Kit for Eccentric Rotating Mass (ERM) actuators, was used to test different haptic properties of objects in two experiments. VITAKI has been successfully used in the identification of 2D shapes and textures, and 3D shapes. However, there are some haptic properties of objects that have not been simulated using VITAKI yet. These are hardness, temperature, weight and size. This paper describes how VITAKI is used to assess whether differences in weight and size can be discriminated using vibrotactile technology. To analyze these new features, two different experiments were carried out by 18 participants. The results of the experiments are presented in this paper, and allowed us to successfully validate the introduced techniques with a success rate higher than 88% in the case of the size, and between 78 and 85% in the case of the weight, depending on the method used.

The use of haptics in virtual reality and video games has received growing attention as a means of enhancing the sensation of immersion in these environments. The sensation of touching virtual objects not only augments the impression of reality but also can improve the performance. However, the design of haptic interactions is not an easy task, and it usually needs a great effort due to the absence of powerful prototyping toolkits. Thus, this article proposes a vibrotactile prototyping toolkit for Eccentric Rotating Mass actuators named VITAKI. The main objective of this platform is to facilitate the prototyping and testing procedures of new vibrotactile interaction techniques for Virtual Reality and video games. A detailed description of the design of the system is provided, presenting the hardware and software elements that make up the VITAKI toolkit. In addition, its application to two different examples to illustrate its use is provided. Finally, a preliminary evaluation of this toolkit is presented. This evaluation is divided into two main stages. On one hand, a study of Olsen’s criteria is performed to analyze its general capabilities. On the other hand, a comparison with previously presented proposals is included too. These two analyses, together with other experiments where the devices created with the toolkit were tested by end users, highlight its main features and its advantages over other proposals.