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.

Share this:

Turn-by-Turn Navigation – the Best Way to Guide Pedestrians?

Pedestrian navigation systems increasingly offer turn-by-turn instructions to guide travellers to their destinations. Turn-by-turn instructions, however, render the human’s inherent navigation skills redundant and lead to a worse understanding of the travelled route. Recently, researchers have increasingly studied providing general directional cues only, so travellers only get a sense of the direction, in which the destination lies, but have to find the route by themselves. This new paradigm may help to reengage travellers in a positive way.

Navigating from a place to another is an essential ability for a self-determined life. When navigating in unknown terrain, e.g. when going for a hike or when visiting a city as a tourist, people become increasingly dependent on navigation aids. Established aids range from signposts over maps to route descriptions. But, thanks to the increasing number of GPS-enabled mobile phones, a new navigation aid is becoming increasingly common: the GPS navigation system.

In principle, these systems behave like car navigation systems. The traveller’s location is displayed on a map, the route is highlighted, and turning instructions are given by symbols or speech. For cars, this way of guiding the driver has shown to be quite successful. Timely and accurate instructions are indispensable as the driver has to follow the traffic rules. For pedestrians, however, this type of information presentation may be too strict. Even worse, when providing too much navigation information, we neglect the human’s inherent navigation abilities and cause even disadvantages. For example, many people report that when driving a route by navigation systems, they cannot remember the route as well as they could before the area of car navigation systems.

Now just imagine a place that is roughly 1 mile away from your current location. If somebody would give you the rough cardinal direction of this place on demand, most people would reach it easily. We tested this kind of navigation in research group and currently offer it in the PocketNavigator. First, the user specifies the destination by selecting it on a map. The handheld then creates vibration patterns that indicate whether the destination is ahead, to the left-hand side, or to the right-hand side.

First studies show that pedestrians can effectively and efficiently navigate with such as directional cue only. Thus, showing the direction of a destination “as the crow flies” could be a valuable additional to turn-by-turn navigation systems for pedestrians.

For more information see  “In Fifty Metres Turn Left”: Why Turn-by-turn Instructions Fail Pedestrians

Share this:

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.

Share this:

How tiny flaws in the user interface can lead to negative user ratings

Usability is important to ensure that your application is successful. In one of our applications we just had to learn that even tiny issues in secondary features can have huge negative effects.

UI professionals keep repeating it: usability is a key to success. One of the most prominent examples is the iPhone 2G. When being released in 2007 it lacked lots of features that were already present in other devices, such as 3G networking, GPS receiver, or a camera. But it arguably it was just the easiest to use phone around then.

However, even when the system is easy to use in general, small usability issues can have huge negative effects. This post reports from an illustrative case that occurred in my research group. Currently, we are working on an Android application called PocketNavigator, which is basically a map-based navigation system.

Screenshot of the PocketNavigators main map view

While the core of the application seemed to be sufficiently easy to use, a rather small ambiguity in a secondary feature brought us bad user ratings.

Due to many requests we added a view that allowed searching for addresses. It provides a text field, where users can enter the address, e.g. “Berlin” or “1 Broadway, New York”.

The address search view as the user initially sees it.
The address search view as the user initially sees it.

For convenience, we stored the last 5 searches and made them accessible through a drop box. To not have to deal with an empty drop box when the application was just installed we initially filled it with five city names.

The address view with the unfolded drop box showing the name of the five initially stored cities.
The initially present cities.

After having released the address view in an update, we faced negative comments in the Android Market saying “only works in five cities”. We could not make sense of this until our colleague complained about the same issue. The UI was giving the impression that the text field only allowed to enter a street and the drop down box had to be used to select the city. So some user’s did not know they could enter any address including a street and a city in the text field.

We addressed the problem by slightly revising the user interface. First, we changed the labels to stress that the user could either enter an address or choose a previously entered one.

New layout of the address view

Second, the drop box would now be filled with complete addresses, such as “Tiergarten Berlin” or “10 Downing Street, London” to demonstrate what types of searches are possible.

The new entries are now more diverse, illustrating different possible entries.

With these countermeasures we hope to avoid such confusion in the future.

In summary, this case is a nice example of how a small usability issue can lead to a bad overall impression of an application. It reinforces that ensuring a good usability should never be neglected when developing an application for a wide audience.

Share this: