They design a device to improve the autonomy of people with visual disabilities

Researchers from the Autonomous University of Madrid (UAM) have designed a device to improve the autonomy of people with visual disabilities. The project, which has the support of Indra and the Universia Foundation, uses vibrations to make the skin act like a low-resolution retina.

The SSD-MOVE project, financed by INDRA and the Universia Foundation through its call for grants for research in accessible technologies, has developed a locomotion assistance device to improve the autonomy of people with visual disabilities.

The project, carried out by the members of the Perception and Movement Research Group of the Autonomous University of Madrid (UAM), is part of the research on VibroTactil Sensory Substitution (SSVT), which uses the tactile perception of vibrations as a substitute for visual perception.

This makes it an optimal method to develop technologies to assist locomotion for people with visual disabilities, since it does not hinder the normal functioning of other sensory modalities as essential as hearing.

According to the researchers, “SSVT is based on the transformation of the distance to surrounding objects into vibrations of an array of small motors in contact with different body surfaces. In this way, the skin acts as a kind of low-resolution retina, in which mechanical vibrations act as visible light.”

Composition of the SSVT device

The objective of the project has been to develop an SSVT integrated into an abdominal girdle with a design that is ergonomic enough to be able to assist in the daily locomotion of its users.

The design is based on four main components: a microcomputer, a Time of Flight camera (ToF, a kind of sonar that works by emitting and capturing infrared light) for detecting the distance to surrounding objects and surfaces, an array of 48 vibrators and a battery. All components are integrated into the girdle itself, which in total weighs less than 800 grams.

The operation of the device has been tested with a task that consisted of crossing a corridor with obstacles in the shortest time possible, trying not to hit the obstacles or the walls.

For this experiment we had the collaboration of both students (who performed the task with their eyes covered with a mask) and people with visual disabilities.

After a 5-minute device familiarization phase performed without vision, all participants were able to complete the task and showed the ability to detect obstacles with the device without strong impact or recoil.

“The participants with better performance used a time close to what is necessary with vision. In other cases, the speed was much slower, probably due to the different degree of security with which each participant faced the task”, details Jorge Ibáñez, who has led the project.

"Participants with visual impairment also showed very heterogeneous speeds, although the number of minor impacts was half that of participants with normal vision", adds the researcher.

SSVT Device Assessment

Regarding the usability of the device, all the participants were satisfied with its operation and with the time needed to learn its use during the familiarization task.

For their part, the participants with visual impairment agreed that this type of mobility aid would be more useful in open and unknown spaces than in a corridor.

The tested device is capable of assisting locomotion in real contexts and has provided valuable feedback to improve its future design.

In the next stage of the project, the device will be tested in a greater variety of contexts in order to develop specific training methods for each one. In addition, work is being done on an improvement of the optical system that allows its safe use outdoors.

Image: Experimentation with an SSVT integrated in an abdominal binder / UAM

Bibliographic references

de Paz, C., Travieso, D., Ibáñez-Gijón, J., Bravo, M., Lobo, L., & Jacobs, DM 2019. Sensory substitution: The affordance of passability, body-scaled perception, and exploratory movements . PlOS ONE , 14(3), e0213342.

de Paz, C., Travieso, D., Jacobs, D., & Ibáñez-Gijón, J. 2022. A comparison of sound and vibration as stimulation sources for a sensory substitution glove. International APPE-SEPEX Meeting , Faro, Portugal.

de Paz, C., Ibáñez-Gijón, J., Travieso, D., & Jacobs, D. Under review. Grasping Objects with a Sensory Substitution Glove. International Journal of Human-Computer studies .