Android Projects Research

A Tactile Compass for Eyes-free Pedestrian Navigation

The idea came up when I was heading back to the hotel from a conference dinner at MobileHCI 2008 in Amsterdam. I had no orientation. The only guide I had was a map on my Nokia phone. Not being familiar with Amsterdam, the route let me right through the busy areas of the city center.

The day before, a cyclist had stolen a mobile phone right out of the hand of another conference attendee. Knowing that made me quite afraid something similar could happen to me too. Without the phone I would have been completely lost.

Here, serendipity hit. Since my research group was already working on tactile displays for navigation and orientation, I wondered whether it was possible to create a navigation system for mobile phones that guided by vibration only, so it could be left in the pocket.

Back at OFFIS we quickly tested a few prototypes, including a hot/cold metaphor and a compass metaphor. The compass metaphor prevailed. The design was to encode the direction the user should be heading (forward, left, right, backwards) in different vibration patterns. Our testing participants liked that design most. Later we tested the vibration compass design a forest and found that it can replace navigation with a map.

The development and the studies was presented at the 13th IFIP TCI3 Conference in Human-Computer Interaction (INTERACT) in Lisbon, Portugal in September 2011. The article is available here.

If you own an Android phone you can try this vibration compass by downloading our PocketNavigator navigation application for free from the Android market.


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Projects Research

Counter-Strike? Research?

Eight people in the twilight, starring at eight screens, hammering their keyboards, wielding their virtual guns … and all for research purposes?

Counter-Strike is a well-known team-based first-person shooter game. Since shooting is an essential part of the game play, it has a bad image in the public. Whenever a young gunman runs amok, Counter-Strike is the first to blame for many conservative politics.

But, games, such as Counter-Strike, can be fantastic research tools. Players need to process a large amount of information as quickly as possible to be successful. For user interface researchers, this comes in handy when novel interface shall be tested in high cognitive workload situations.

In our previous work we had developed a tactile user interface that allowed sensing the location of people via the sense of touch. To test this user interface we integrated it into Counter-Strike. It gives the wearer a sense of where the team mates are at any time.

The direction of the team mate is indicated by where the vibration occurs. The distance is indicated by the number of pulses.


We conducted a study where two teams of participants compete against each other. The teams where alternately equipped with the tactile location sensing system. We found that the tactile location sensing system increased the team’s situation awareness and its performance. Despite the games high cognitive demands the participants were able to interpret the tactile cues.

And the best is … this project scored a publication at the most prestigious scientific conference on human-computer interaction: the ACM Conference on Human Factors in Computing Systems (CHI).

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Projects Research

Sensing your Friends’ Locations via the Sense of Touch

Imagine visiting a crowded place with a bunch of friends. Wouldn’t it be great to unobtrusively stay aware of where they are? Thanks to 3G, GPS, and powerful handhelds, today it is perfectly possible to share the location in such a mobile context.

A remaining problem is how to present the friends’ locations to the user. Instead of constantly pulling the device out of your pocket you might rather want to enjoy the event. The environment may be noisy and crowded, making the interaction with the device difficult in general.

We therefore developed a system that displays the location of friends via the sense of touch. Specifically, we aimed at conveying the direction and the distance of a number of friends, so the user would have a rough idea of where her/his friends are.

For communicating via the sense of touch we used a tactile belt. A tactile belt is a belt that comprises a number of vibration motors (Tactors), which are distributed all around the waist when the belt is worn. It has been demonstrated by other research groups that users can easily interpret the vibration patterns as pointing directions. If for example the front vibration motor is turned on the belt seems to point forward.

In our system we used this to inform the wearer in which direction a friend is. Since we wanted to display the direction of more than one friend we iterated through the friends. Each friend’s direction is displayed for a short time before the system switches to the next friend.

To convey a location we added a distance cue into the tactile signal. From the direction and the distance we assumed the user could get a rough understanding of the friend’s location. We tested three different ways of encoding the friend’s distance in the vibration.

In the rhythm-based distance encoding the belt would pulse a number of times into the direction of the friend. The number indicates the distance. The more pulses, the further the friend is away.

In the duration-based distance encoding the belt would use a single pulse to display the friend’s direction. The distance is encoded in the length of the pulse. The longer the pulse is the further the friend is away.

In the intensity-based distance encoding the belt would use a single pulse to display the friend’s direction. The distance is encoded in the pulse’s intensity. The further the friend is away, the less intense the pulse becomes.

In an experiment we compared the three distances encodings to find out how accurate and intuitive they are. The rhythm-based encoding allowed the most accurate and intuitive distance perception. However, the intensity-based and the duration-based distance encodings made it subjectively easier to judge the friend’s direction.

Altogether, we could show that providing a rough estimate of e.g. the location of people via the sense of touch is possible.

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Projects Research

Vibration-enhanced Paper Map Navigation

Maps are one of the oldest known information artifacts. An even in the times of GPS navigation systems, people still use them to find their ways in unknown environments.

One of the challenges when navigating by a map is that the map’s abstract content has to be matched to the traveler’s environment. It has for example been found that maps are easier to use when they are rotated so they align with the environment. We were interested if that matching would become easier if the user always knew were the destination was.

In our research we therefore coupled a GPS-enabled handheld with a vibro-tactile belt. The belt consists of eight vibration motors that equally distribute around the user’s waist. A built-in compass allows understanding in which direction the user is facing. The belt was then use to constantly vibrate into the direction of the traveler’s destination.

Traveler with a map and our vibro-tactile belt. The belt vibrates     into the direction of the traveler's destination.
Concept: convey the general direction of the destination with a vibro-tactile belt


In a field experiment with 16 participants we tested our approach in the wild. The participants had to reach two destinations, one with a paper map only and the other with the additional support of the vibro-tactile belt.

We found that the vibrational cues made participants less on the map, lose their orientation less often, and take shorter routes.

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