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Navigation aid of the ASSAM Walking Assistant

Usability research by Bartiméus and the Accessibility Foundation

In the literature mobility means the possibility of moving freely without the support of any accompanying person at home or in public and open spaces. Moving freely can be a challenge for many blind and visually impaired people. In order to explore unfamiliar and unknown places, blind and visually impaired people usually need the assistance of another person, a dog or a white cane (1). 

With advances in technology, blind people increasingly also use technological aids for navigation and exploration. Navigation apps can be used on mobile phones to help navigate and self-localize. These technological aids help blind and visually impaired people to improve both their mobility and their independence. The Navigation Aid and Walking Assistant software and supporting hardware have been developed as part of the European project Assistance for Safe Mobility (ASSAM) to help blind people to find their way in an in- and outdoor environment. This system assists navigation and orientation in real time and can improve the possibility of moving freely and independently.

How?

The Navigation Aid software fuses odometry (provided by sensors in an OdoWheel and the tablet or smartphone), GPS and map information with the help of a Monte Carlo particle filter to be able to provide precise outdoor localization. The Walking Assistant with laser scanner support can locate persons or objects in the path and can be of great use in out- and indoor environments. Our blind test users tested these assistants during a usability research session at the Bartiméus Accessibility Foundation in Utrecht, The Netherlands. What do some of our test users Hans (63), Bianca (39) and Roel (64) think about the navigation aid of the ASSAM Walking Assistant prototype? Is it sufficient and ready to use for blind and visually impaired people?

Hans lives in Utrecht and used his dog and a navigation app to find his way to the Accessibility Foundation at the other side of the town. “Thanks to my navigation app, I can find my way around and move freely.”

Creating mental maps

Hans with the ASSAM walking assistantMany blind people are able to create mental maps from sensory images by compensating the lack of sight and augmenting the information from the other senses. Mainly tactile and auditory information are used to replace or complement the ability to see a place. In order to create a so-called mental map, a blind person tries to mentally build the spaces by identifying obstacles around him and searching environmental information.

How can the Walking Assistant ensure the creation of mental maps in wayfinding and exploration of an environment? The Walking Assistant provides information about the environment through tactile and audio feedback. The vibration element in the iHandlebars is able to send messages about the route. Alternatively, the Navigation Aid may provide audio messages through speech.

The Navigation Aid user-interface is designed to help navigate to a target through visual and auditive modalities. In reality, when we tested the walker, neither the navigation aid nor the odometry was ready to be connected to the computer of the walker or to each other. This of course had some consequences for the testing. That is why we focused on wishes and ideas about navigation during the focus group session. We installed a small vibration element ourselves to start the discussion with the test users.

 

Navigation Aid

The ASSAM Navigation Aid has different tabs. One to show the map during navigation, the other to show the compass and one is a target selection tab. But, wait a minute! How is a blind person able to get this visual information? Only during navigation, the user can be guided by audio turn-by-turn signals and haptic modalities by the iHandlebars. How is a blind person supposed to select an address in the Navigation Aid? This is currently possible with the speech interface after the app is made accessible. To make sure the ASSAM Walking Assistant is suitable for blind and visually impaired users, Hans, Roel and Bianca give some suggestions to keep in mind regarding the navigation aid.

Assam focus group sessionSuggestion 1: Make sure the navigation aid is accessible for blind and visually impaired people from the start. Make sure the blind user can use the tablet and the other features of the walker.

Bianca, Roel and Hans all use existing navigation apps like NAVIGON and BlindSquare. They use these apps because they give detailed information about the environment and are accessible for blind and visually impaired people. BlindSquare for example is a GPS app specially designed for blind and visually impaired users. It describes the environment, announces points of interest and street intersections. An important reason Bianca, Roel and Hans use this app is because the different functions can be accessed through an audio menu via headset or speaker. They are dependent on the information that their navigation apps present.

Suggestion 2: The navigation instructions of the ASSAM Navigation Aid need to be very clear and precise. Only giving a direction like turn left or right is not enough. The test users suggest using the clock positions for navigation instructions and using the twelve hour markings with the directions in which they point. By the way: the current interface is adjustable for this purpose, in particular front, front-left etc. We would expect users to prefer qualitative directions rather than 12-hour indications as that may include higher cognitive requirements.

To be more precise: 12 o’clock means straight ahead, 3 o’clock means to the right, 6 o’clock means turn around and 9 o’clock means to the left. All the other hours refers to directions that are not directly in line with the four major directions. Hans prefers to receive the navigation instructions through a speaker. For example, a speaker that can be attached to his jacket so it is close to his ears. Sounds from the Walking Assistants tablet might be too soft in outdoor situations like a busy intersection. Hans does not like the idea of using a headset, because then he feels isolated from street noise. He could be helped with a bone-conducting headphone.

Suggestion 3: Make sure the detailed navigation instructions can be understood and heard properly in all circumstances, for example via a portable speaker.

Even though the test users were very excited about all the different features of the ASSAM Walking Assistant, they warned for an information and signal overload. In their opinion messages through audio and vibrations about navigation can be a bit overwhelming.

Suggestion 4: To prevent a multimodel channel overload, use a single modality to give the navigation instructions, so by either audio or by vibrations. The test participants all preferred the audio instructions for navigation and suggested to use the vibrating handlebars for warnings about objects.

Roel has some problems with moving freely. He has difficulties with walking stairs, change from the road to a sidewalk and use high doorsteps. He says that besides navigation, some specific information about the height of such ‘obstacles’ would really help him. Currently the Navigation Aid tries to avoid unsuitable paths, e.g. with steps.

Suggestion 5: The navigation should also give general and specific environment information on demand, such as the height or presence of stairs or sidewalks, but also information on the status of a traffic-light signal. This information should keep the user on a safe path.

Outdoor navigation

Nina and Hans testing the Assam walking assistantASSAM Navigation Aid is most useful in outdoor environments. A blind person can orient himself in already known places by recognising known features or by perceiving unknown but regular objects like walls or tables.  Outdoor navigation for blind people is essential in their possibility of moving freely. They can create mental maps of environments thanks to navigation instructions. Hans, Roel and Bianca are very pleased about the navigation possibilities of the ASSAM Walking Assistant, but they need very precise instructions. 

 

 

Literature used:

  • (1) Schneider-Hufschmidt, M. et al.
    2003  Human Factors guidelines for multimodal interaction, communication and navigation.
  • Krieg-Brückner, B. et al.
    2013  Navigation Aid for Mobility Assistants.
  • D’Atri, E. et al.
    2007  A system to aid blind people in the mobility: A usability test and its results.
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