Validation of an eBAT as a mobility aid for blind people

One of the challenges faced by blind persons to achieve optimal mobility is the detection and avoidance of obstacles located in their travel path. Besides the widely used white cane, alternative or complementary devices have been developed, such as electronic aids that provide feedback about the environment. However, the devices available have been unable to provide an optimal solution with widespread acceptance, motivating the present work. The eBAT (electronic Buzzer for Autonomous Travel) is designed to offer optimal protection and employs the user's own mobile phone for easier use and reduced manufacturing costs. For this work, a group of 25 blind individuals was used to validate the eBAT based on the single-subject with reversal method (ABA study). The results show a significant decrease in the number of involuntary contacts in an unknown travel path between the first phase of the study, which did not involve the eBAT, and the second, where it was used. When the device was again removed in the third phase, the number of contacts rose. We may therefore conclude that the eBAT fills an important gap in mobility aids for blind people, yielding a clear benefit by reducing the participants' feeling of insecurity.

Low-Cost Ultrasonic Range Improvements for an Assistive Device

To achieve optimal mobility, visually impaired people have to deal with obstacle detection and avoidance challenges. Aside from the broadly adopted white cane, electronic aids have been developed. However, available electronic devices are not extensively used due to their complexity and price. As an effort to improve the existing ones, this work presents the design of a low-cost aid for blind people. A standard low-cost HC-SRF04 ultrasonic range is modified by adding phase modulation in the ultrasonic pulses, allowing it to detect the origin of emission, thus discriminating if the echo pulses come from the same device and avoiding false echoes due to interference from other sources. This improves accuracy and security in areas where different ultrasonic sensors are working simultaneously. The final device, based on users and trainers feedback for the design, works with the user’s own mobile phone, easing utilization and lowering manufacturing costs. The device was tested with a set of twenty blind persons carrying out a travel experiment and satisfaction survey. The main results showed a change in total involuntary contacts with unknown obstacles and high user satisfaction. Hence, we conclude that the device can fill a gap in the mobility aids and reduce feelings of insecurity amongst the blind.

Quantifying the wind dispersal of Culicoides species in Greece and Bulgaria

This paper tests the hypothesis that Culicoides (Diptera: Ceratopogonidae) species can be propagated by wind over long distances. Movement patterns of midges were inferred indirectly from patterns of the spread of bluetongue outbreaks between farms (using outbreak data from 1999-2001 for Greece, Bulgaria and Turkey) and then matched to concurrent wind patterns. The general methodology was to determine wind trajectories to and from each outbreak site based on the horizontal and vertical wind components of the European ReAnalysis-40 (ERA-40) dataset from the European centre for medium-range weather forecast (ECMWF). Forward trajectories (downwind or where the windvectors pointed to) and backward trajectories (upwind or where the wind-vectors originated from) were calculated for each outbreak for the period from one week before to one week after it had been recorded. These wind trajectories were then compared with the general outbreak patterns taking into consideration the different serotypes involved. It was found that the wind trajectories could be matched to the temporal distribution of the outbreak cases. Furthermore, the spread of the infected vector via the calculated wind trajectories was corroborated by molecular evidence. The conclusion is that the methodology presented is appropriate for quantifying the risk of spread of infected Culicoides midges by wind and that this approach could form an important component of a regional early-warning system for bluetongue.