Thorsten Schwarz

Towards Displaying Graphics on a Cheap, Large-Scale Braille Display

Large-scale Braille displays will make participation in modern media society easier for visually impaired people. At the moment extensive research is done on developing new technologies for affordable refreshable Braille displays. However, the developed displays often do not match the user requirements. This is because most of the engineers entrusted with the development know little to nothing about the potential users of their systems. To bridge that gap we carried out an online survey. Within this survey 69 people who either are visually impaired themselves or take care of someone who has lost his/her sight stated their opinion on how a large-scale refreshable Braille display should be designed. The results of this survey were used to build a first prototype of a large-scale refreshable braille display for displaying text and tactile graphics. This prototype relies on cheap, energy efficient microfluidic phase change actuators.

Tuning the Strain in LaCoO3 Thin Films by the Heteroepitaxial Growth on Single Crystal Substrates

Epitaxial strain in LaCoO3 thin films has been changed by the growth of thin films on different substrate materials, i.e., (001) oriented SrLaAlO4, LaAlO3, SrLaGaO4, (LaAlO3)0.3(Sr2AlTaO6)0.7, and SrTiO3. The films were deposited by pulsed laser deposition. The lattice mismatch of the in-plane lattice parameters between the substrate, a s, and LaCoO3, a b, ∈ = (a s−a b)/a b, ranges from ∈ = −1.32% for the growth on SrLaAlO4 to ∈ = +2.76% for films on SrTiO3. The characterization of the structural properties such as film lattice parameters, unit cell volume and epitaxial strain was carried out by θ/2θ scans and reciprocal space mapping on a two-circle and four-circle x-ray diffractometer, respectively. We succeeded in the growth of single phased (001) oriented LCO films on all the substrate materials. For the lattice parameters of the LaCoO3 films we observed a quasi-elastic behaviour in the range of −1% < ∈ < +2 %. The out of plane lattice parameter c increases and the in-plane lattice parameters a and b decrease nearly linearly with decreasing in-plane lattice parameter a s of the substrate material. This indicates an elastic coupling of the film to the substrate and therefore the possibility to tune the Co-O bond-length and thus the crystal field splitting, Δ CF, by epitaxial strain.

Development of a Graphic and Braille Optimized Plotter for the Blind and Visually Impaired

With the development of this plotter, a cost-effective and easy assembly was created to allow a better accessibility to well-recognizable braille text and tactile graphics on standard DIN-A4 paper for blind and visually impaired users. In comparison to currently employed systems, the developed device consists of a commercially available X/Y-plotter, which enables a movement in two orthogonal directions at once. Thus, not only the embossing of single dots, but also of continuous lines on a flat surface is possible. The plotter was extended by a solenoid that can change the force on a convertible embossing pen in Z-direction. Further parts were constructed and added to enable material feeding, material removal and paper fixation while printing. In a survey with six blind and visually impaired people, the results of the plotter were tested for good readability and recognition and compared to a conventional needle-based-system. Most of the participants would use the results produced by the plotter at hand in their daily life.

Prototype development of a low-cost vibro-tactile navigation aid for the visually impaired

Vibro-tactile support for navigation tasks is helpful, not only for visually impaired people. However many different prototypes exist which are not available for experimental usage or commercial ones are expensive. We developed a low-cost prototype of a wristlet and anklet that can easily be rebuild. We evaluated them in a two step procedure with 11 and 10 participants. Both prototypes are easy to use and comfortable to wear. However, the wristlet had a high error rate so that it was not used in the second test. Comparisons between the anklet and voice guidance during navigation in the second test showed the potential of vibration for navigation tasks, but implied a refinement of the design, which will be tested in further studies.

An inclusive and accessible LaTeX editor

In this paper, we discuss the reasons which led us to propose LaTeX as mathematical notation to visually impaired students and why there is need for an accessible LaTeX editor. We performed an accessibility test for a selection of three LaTeX editors, to investigate their capabilities to satisfy the needs of these users. The evaluation of the results showed that it was necessary to develop an own editor. The first prototype was preliminarily tested, proving that, paying attention to the GUI library and the development environment, it is possible to develop a GUI with a high level of compatibility with assistive technologies like screen readers and magnifiers. The editor achieved a satisfying ranking in the user-tests which encourages further development of the software.

Accessible EPUB: Making EPUB 3 documents universal accessible

Current document standards have the characteristic that they can only serve one group of users under the aspect of vision (sighted, visually impaired or blind reader). Wouldn’t it be nice if one documentformat could combine all properties in one document? This paper presents a new approach of an universal accessible version of EPUB 3 documents, which will allow sighted, visually impaired and blind readers to use and share the same EPUB 3 document by an “integrated switching mechanism” to change the output format. Furthermore, we will introduce a simple word processing tool that allows to easily create such accessible EPUBs without knowing how an EPUB file is constructed or created.

Optical Braille Recognition

Analog production methods for braille material, like braille typewriter or thermoforming processes, are still in use. Thereupon exists the wish to archive and preserve those materials, e.g. by digitalizing it. Research in the field of braille writing system detection and braille transcription has been sparse. Therefore we present a system to digitize printed Braille-documents.