Exploring Distance Encodings with a Tactile Display to
Convey Turn by Turn Information in Automobiles
Amna Asif1, Wilko Heuten2, Susanne Boll1
1University of Oldenburg 2OFFIS
Escherweg 2 Escherweg 2
26121 Oldenburg, Germany 26121 Oldenburg, Germany
famna.asif—susanne.bollg@informatik.uni-oldenburg.de heuten@offis.de
ABSTRACT
Visual and auditory displays successfully complement each
other presenting information in car navigation systems. How-
ever, they distract the visual and auditory attention of the
driver, which is needed in many primary driving tasks, such
as maneuvering the car or observing the traffic. Tactile in-
terfaces can form an alternative way to display spatial in-
formation. The way of how exactly information should be
presented in a vibro-tactile way is explored rarely. In this
paper we investigate three different designs of vibro-tactile
stimulation to convey distance information to the driver us-
ing a tactile waist belt. We explore the tactile parameters
intensity, rhythm, duration, and body location for encoding
the distance information. We conduct a comparative experi-
ment on a real navigation scenario in an urban environment
to evaluate our designs.
In our study we discovered that rhythm and duration are suit-
able parameters to generate tactile stimulation for encoding
distance information. In this way the driver perceives count-
able vibro-tactile pulses, which indicate the distance in turn
by turn instructions. The approach is found be simple way
of encoding complex navigational information.
ACM Classification Keywords
H.5.2 User Interfaces: Haptic I/O; 1.3.6 Methodology and
Techniques: Interaction techniques
General Terms
Human Factors, Experimentation
Author Keywords
Car navigation system, Tactile interface
INTRODUCTION AND MOTIVATION
The activity of driving is multi-tasking and complex [12].
Vehicles are equipped with a number of distinct information
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systems to support the driver. A car navigation system is
one of the promoted and preferred information systems for
cars. Visual and auditory displays in the present car navi-
gation systems are successful to provide spatial information.
However, the car navigation system increases a demand of
the driver’s visual and acoustic attention while driving and
are subject to distract the driver. The visual attention of the
driver is essential in the primary task of driving, which is
for example steering the car, using brakes and controls as
well as observing the traffic. Pauzie and Marin [10] investi-
gated that aging drivers spent 6.3% and young drivers spent
3.5% of their driving time glancing at the screen. Auditory
displays on the other hand are challenging in a noisy envi-
ronment. The driver performs a multiple number of primary
and secondary tasks on visual and auditory displays that can
impose mental workload [4] and distraction [12], which is
harmful for safety of driving.
A tactile display can be used as an alternative interface for
the car navigation system to reduce the mental workload
and the distraction, following the Multiple Resource The-
ory (MRT) [21]. Two important parameters of the turn by
turn navigation are direction and distance [2, 19]. In pre-
vious studies car simulators have been used to evaluate the
vibro-tactile distance encoding. However, the investigation
of the precise approach of vibro-tactile distance presentation
in a real environment is missing. We investigated a number
of the encodings based on rhythm, intensity and duration to
discover an appropriate approach for the vibro-tactile dis-
tance encoding. We evaluated three vibro-tactile distance
encodings in an experiment: (1) Only rhythm based distance
encoding (2) Rhythm and intensity based distance encoding
(3) Rhythm and duration based distance encoding. In our
study, we focused on comparing different methods of con-
veying the distance with the vibro-tactile feedback in real
urban environments. The study shows success of duration in
combination with rhythm based distance encoding in the car
navigation systems.
In the remainder of this paper, Section 2 introduces the reader
with the state-of-the-art tactile interfaces and related approaches
of the vibro-tactile distance and direction encoding in auto-
mobiles. The design space and the vibro-tactile distance en-
codings are described in Section 3. The experiment details
are presented in Section 4. In Section 5 we report the find-

ings. In Section 6 we discuss the answers to our research
question and further findings. We close the paper with a
conclusion in Section 7.
RELATED WORK
Previous research has shown that the tactile displays were
effectively used to provide navigation aids to the pedestri-
ans and blind users. McDaniel et al. [9] present a scheme
for using tactile rhythms to convey intimate, personal, social
interpersonal distances to blind users. ActiveBelt [16] con-
sists of a number of vibration components integrated into a
belt or a vest. The vibration components are equally dis-
tributed around the person’s body and activated for showing
him a direction. Tactile Wayfinder [5] was evaluated for the
task of pedestrian route guidance. The tactile Wayfinder sup-
ported the pedestrian in orientation, choice of route, keeping
through track, and recognition of destination. PeTaNa [20] a
torso based wearable system was evaluated to present direc-
tion and distance information to soldiers in the field. The di-
rection information was presented on the respective location
of torso of the soldier. Distance was coded with the tempo-
ral rhythm on the vibration. van Erp et al. [19] investigated
different distance encoding schemes with pedestrian partic-
ipants. The vibration rhythm was used to code the distance
and the body location was used to code the direction. An ad-
ditional experiment investigated usefulness of tactile display
with a helicopter and a fast boat. Straub et al. [14] used a
vibro-tactile waist belt to encode distance for the pedestrian.
They used four distance encodings based on the parameters
of intensity, frequency, position (which tactor), and patterns.
Pielot et al. [11] presented a position and spatial distance of
several people with the help a tactile torso based display in
fast paced 3D game. The results showed that the location of
the team members can be effectively processed with the help
of the tactile display in high cognitive demand. The team
showed a better team play and higher situation awareness.
The findings of the previous studies encourage the fact that
it is possible to encode distance with tactile displays. The
effectiveness of the tactile display for presenting direction
and distance information to blind and pedestrians motivate
the idea to discover the approach to code distance in vibro-
tactile signals in car navigation systems.
Furthermore, the tactile interface is effectively used in Ad-
vanced Driver Assistance Systems on commercial scale e.g.
in Citroen1 and Audi2 in the seat and steering wheel, re-
spectively. Similarly, the previous studies investigated the
feasibility of the tactile channel in vehicle information sys-
tems e.g. in car navigation systems. A vibro-tactile seat
is developed with the characteristics of a matrix with 6 x 6
elements with interaction area of a 430 by 430 mm with dy-
namically modifying haptic feedback based on the driving
sitting posture [13]. A prototype steering wheel [7] is inte-
grated with six tactile actuators. The steering wheel is used
to display the direction in a car simulator. The best driving
performance is attained by combining tactile display with a
visual display or an auditory display. A seat fitted with 24
1http://www.citroen.com.hk/tech/sec 04.htm
2http://www.audiworld.com/news/05/naias/aaqc/content5.shtml
vibrators in an 8 x 8 matrix [6] is used to evaluate the abil-
ity of drivers to distinguish up to eight different directions.
The distance information is presented by van Erp and van
Veen [17] with vibrocon (vibro-tactile icon) for three dis-
tance steps of 250 m, 150 m, and 50 m. The information is
presented to the users by activating the four tactile actuators
either under the left or right leg of the driver. The results of
an evaluation in the simulator show that the tactile interface
helps to reduce the visual burden of the drivers. We take
the opportunity to explore the tactile encoding for spatial in-
formation in the real driving environment. van Erp and van
Veen encoded a distance information in the form of rhythm
patterns though it is possible to explore more methods of
distance encoding. The proof-of-concept study shows that
using vibro-tactile displays in the car is useful for presenting
distance information.
In the previous research, torso based tactile displays are suc-
cessfully employed to present navigation information to the
blind users and pedestrians but parameters still require ex-
ploration in the automobiles. In the previous studies [9,
11, 14, 19], a number of vibro-tactile encoding schemes are
compared to display distance information to the team play-
ers, pedestrian and blind users. Besides previous proof-of-
concept studies [17] the tactile parameters are still required
to explore to discover an appropriate approach of encoding
distance with vibro-tactile signals in the car navigation sys-
tem. In this paper a similar comparative approach is used to
explore the tactile parameters to encode distance information
in the car navigation system.
EXPLORING DISTANCE ENCODING WITH VIBRO-TACTILE
SIGNALS
Car navigation systems provide route guidance to the driver
towards a destination [15]. In our study, we used a tactile
waist belt to provide turn by turn directions and distance in-
formation to the driver. Figure 1 presents example cues that
DirectionDirecton
Very-far
Ver
Very
Very-yfa Very
Very
Very
Very
Figure 1. The direction and distance instruction presented by the tactile
feedback, as the car approaches the crossing.
are conveyed to the driver through the tactile belt while ap-