Beatriz Defez

Sensory navigation device for blind people

This paper presents a new Electronic Travel Aid (ETA) ‘Acoustic Prototype’ which is especially suited to facilitate the navigation of visually impaired users. The device consists of a set of 3-Dimensional Complementary Metal Oxide Semiconductor (3-D CMOS) image sensors based on the three-dimensional integration and Complementary Metal-Oxide Semiconductor (CMOS) processing techniques implemented into a pair of glasses, stereo headphones as well as a Field-Programmable Gate Array (FPGA) used as processing unit. The device is intended to be used as a complementary device to navigation through both open known and unknown environments. The FPGA and the 3D-CMOS image sensor electronics control object detection. Distance measurement is achieved by using chip-integrated technology based on the Multiple Short Time Integration method. The processed information of the object distance is presented to the user via acoustic sounds through stereophonic headphones. The user interprets the information as an acoustic image of the surrounding environment. The Acoustic Prototype transforms the surface of the objects of the real environment into acoustical sounds. The method used is similar to a bat’s acoustic orientation. Having good hearing ability, with few weeks training the users are able to perceive not only the presence of an object but also the object form (that is, if the object is round, if it has corners, if it is a car or a box, if it is a cardboard object or if it is an iron or cement object, a tree, a person, a static or moving object). The information is continuously delivered to the user in a few nanoseconds until the device is shut down, helping the end user to perceive the information in real time.

Measurement of Aerodynamic Coefficients of Spherical Objects Using an Electro-optic Device

Aerodynamic coefficients are required to determine the trajectory of moving objects. These coefficients are typically obtained measuring the forces acting on the object using a wind tunnel. Wind tunnels are expensive and not easily available; therefore, their use is limited. This paper presents a new procedure to measure aerodynamic coefficients of spherical objects using an electro-optic device. Forces are calculated from velocity changes instead of being directly measured. The procedure is based on a method to measure the three components of the instantaneous velocity vector at known positions. The main advantages are size, cost and complexity reduction compared to wind tunnels. These advantages open the possibility of integration in production lines for quality control. A prototype has been built and tested using soccer balls.

Fuzzy Directional-Distance Vector Filter

A well-known family of nonlinear multichannel image filters uses the ordering of vectors by means of an appropriate distance or similarity measurebetween vectors. In this way, the vector median filter(VMF), the vector directional filter(VDF) and the distance directional filter(DDF) use the relative magnitude differences between vectors, the directional vector difference or a combination of both, respectively. In this paper, a novel fuzzy metricis used to measure magnitude and directional fuzzy distancesbetween image vectors. Then, a variant of the DDF using this fuzzy metricis proposed. The proposed variant is computationally cheaper than the classical DDF. In addition, experimental results show that the proposed filter receives better results in impulsive noise suppression in colour images.

Simulation of the Evolution of Floor Covering Ceramic Tiles During the Firing

Finding the geometry and properties of a ceramic tile after its firing using simulations, is relevant because several defects can occur and the tile can be rejected if the conditions of the firing are inadequate for the geometry and materials of the tile. Previous works present limitations because they do not use a model characteristic of ceramics at high temperatures and they oversimplify the simulations. As a response to such shortcomings, this article presents a simulation with a three-dimensional Norton’s model, which is characteristic of ceramics at high temperatures. The results of our simulated experiments show advantages with respect to the identification of the mechanisms that contribute to the final shape of the body. Our work is able to divide the history of temperatures in stages where the evolution of the thermal, elastic, and creep deformations is simplified and meaningful. That is achieved because our work found that curvature is the most descriptive parameter of the simulation. Future work is to be realized in the creation of a model that takes into account that the shrinkage is dependent on the history of temperatures.

Virtual Moving Sound Source Localization through Headphones

Humans are able to detect, identify and localize the sound source around them, to roughly estimate the direction and distance of the sound source, the static or moving sounds and the presence of an obstacle or a wall [Fay and Popper, 2005]. Sound source localization and the importance of acoustical cues, has been studied during many years [Brungart et al., 1999]. Lord Rayleigh in his “duplex theory” presented the foundations of the modern research on sound localization [Stutt, 1907], introducing the basic mechanisms of localization. Blauert defined the localization as “the law or rule by which the location of an auditory event (e.g., its direction and distance) is related to a specific attribute or attributes of a sound event” [Blauert, 1997]. A great contribution on sound localization plays the acoustical cues, Interaural Time Difference ITD and Interaural Level Diference ILD, torso and pinnae (Brungart et al., 1999), [Bruce, 1959]. [Kim et al., 2001] confirm that the Head Related Transfer Functions (HRTFs) which represent the transfer characteristics of the sound source in a free field to the listener external ear [Blauert, 1997]), are crucial for sound source localization. An important role in the human life plays the moving sound localization [Al’tman et al., 2005]. In the case of a moving source, changes in the sound properties appear due to the influence of the sound source speed or due to the speed of the used program for sound emission. Several research have been done on static sound localization using headphones [Wenzel et al., 1993], [Blauert, 1997] but few for moving sound source localization. It is well known that on localization via headphones, the sounds are localized inside the head [Junius et al., 2007], known as “lateralization”. Previous studies [Hartmann and Wittenberg, 1996] in their research on sound localization, showed that sound externalization via headphones can be achieved using individual HRTFs, which help listeners to localize the sound out in space [Kulkani et al., 1998], [Versenyi, 2007]. Great results have been achieved with the individual HRTFs, which are artificially generated and measured on a dummy head or taken from another listener. Due to those HRTFs, the convolved sounds are localized as real sounds [Kistler et al., 1996], [Wenzel, 1992]. This chapter presents several experiments on sound source localization. Two experiments are developed using monaural clicks in order to verify the influence of the Inter-click interval on sound localization accuracy. In the first of these experiments [Dunai et al., 2009] the localization of the position of a single sound and a train of sounds was carried out for different inter-click intervals (ICIs). The