WO2008061539A1

WO2008061539A1 - Method and apparatus for communicating navigational instructions to a user

Info

Publication number: WO2008061539A1
Application number: PCT/EP2006/011096
Authority: WO
Inventors: Zoran Radivojevic; Ari Raatikainen
Original assignee: Nokia Corporation
Priority date: 2006-11-20
Filing date: 2006-11-20
Publication date: 2008-05-29
Also published as: EP2084494A1; CN101542238A

Abstract

A method for communicating navigational instructions to a user. The user wears/touches skin electrodes that are operatively coupled to a navigational device. A navigational device generates signals for activating the skin electrodes based on direction indications generated by the navigation device. An apparatus including a navigational device and at least two skin electrodes. The navigational device generates activation signals for the skin electrode based on navigational instructions generated by the navigational device.

Description

METHOD AND APPARATUS FOR COMMUNICATING NAVIGATIONAL INSTRUCTIONS TO A USER

FIELD OF THE INVENTION

The present invention relates to a method for communicating navigational instructions to a user.

Further, the invention relates to a navigational apparatus that generates navigational instructions for a user .

BACKGROUND OF THE INVENTION

Navigation devices, such as mobile GPS navigation devices to communicate the navigational instructions in audiovisual or tactile form to users. Hereto, the navigational devices are provided with a display, a loudspeaker and a vibrator. These technologies are advanced. however, they have their limitations. For instance, haptic user interfaces typically require a lot of energy to operate, which is not acceptable for most mobile battery operated devices. Optical information requires a user to direct his view to the display, which may not be desirable when the user is for example driving a car. Audible instructions can be undesirable in very silent environments or unperceivable in very loud environments .

DISCLOSURE OF THE INVENTION

On this background, it is an object of the present invention to provide a method of communicating navigational instructions to the user that overcomes or at least reduces the limitations of the methods described above. This object is achieved by providing a method for directing a user with a navigational device, the navigational device being operatively coupled to at least two skin electrodes including placing the at least two skin electrodes on the skin of the user, generating navigational directions for user, converting the navigational directions to signals for activating the electrodes .

Thus, a user interface is created that does not require the user to direct his/her eyes to the display, that does not use large amounts of energy, and that can be used in both very quiet and very loud environments.

Preferably, one of the at least two skin electrodes is placed on the left side of the body of the user and the other of the at least two electrodes is placed on the right side of the body of the user.

The electrodes can be integrated in other objects like a car steering wheel and user is in intimae contact while holding the steering wheel and driving/guiding the car. Furthermore, other suggested integration of skin electrodes can be for instance in shoe insole or in a belt equipped with 2-3 electrodes.

The method may further include activating the skin electrode placed on the left side of the body when the navigational directions indicate that the user should turn left and activating the skin electrodes placed on the right side of the body when the navigational directions indicate that the user should turn right. The method may also include the use of a third skin electrode, the third electrode preferably being placed in the middle and/or on the back of the body of the user.

The method may further include activating the third electrode when the navigational directions indicate that the user should turn back.

The method may further include activating the electrodes in a predetermined sequence. Various sequences of activation and allow for a larger number of different instructions to be communicated to a user.

Preferably, the method includes the use of a plurality of different sequences, each having a different meaning associated therewith.

The method may further include activation of any of the skin electrodes by the use of electro-pulse sequences. The electropuise sequences may be composed of two parts, and an active part with a basic frequency, time length and a silent part free of stimulations with another predetermined time length. An activation of any of the skin electrodes may comprise a plurality of the two parts.

The above limitations are also removed or at least reduced by providing an apparatus including a navigation device operatively coupled to two or more skin electrodes, the navigation device being configured to generate navigational instructions in the form of activation signals for the one more skin electrodes. Thus, an apparatus is provided that can communicate navigational instructions to a user without the need for the user looking at a display, or listening to a loudspeaker.

Preferably, the navigational device generates navigational instructions for a user, and the navigational device is configured to activate one or more of the electrodes when the navigational instructions indicate that the user needs to change direction.

The apparatus may include a left skin electrode and a right skin electrode, the navigational device is configured to activate the left skin electrode when the navigational instructions indicate that the user needs to turn left, and the navigational device is configured to activate the a right skin electrode when the navigational instructions indicate that the user needs to turn right.

The apparatus may comprise device comprises a central or rear skin electrode, the navigational device is configured to activate the central or reader skin electrode when the navigational instructions indicate that the user needs to turn around.

Preferably, the navigational device is configured to generate a sequence of activations of any of the electrodes when they navigational instructions indicate that the user needs to change direction.

The navigational device may be configured to activate the left to electrode, the right to electrode and the middle or rear electrode sequentially when the navigational instructions indicate that the user needs to change level .

The navigational device and the electrodes may be connected by wires.

The navigational device and the electrodes may be wirelessly connected.

The navigational electrodes can be integrated in a vehicle steering wheel (navigational steering wheel cover) or on the parts of the wheel support. When driver needs navigational suggestion it is delivered through electro stimuli or vibrations on the wheel cover directly.

The navigational electrodes can be integrated into a shoe insole. The foot skin is extremely sensitive and any small stimuli will be easily felt by the user. This part of user body is very suited for very low power stimuli navigational informatics. In case of the integration in a belt/stripe like form the material used can be elastic rubber which will provide permanent attachment of the electrodes to the user skin. Notice that the belt/strip is meant to be used under the clothes placed directly on the skin.

Preferably, the navigational device includes a position detector and map data. The navigational device may include a processor configured to determine a route based on user instructions, position data that and map data.

The navigational device may receive its position and map data from a remote server via a wireless connection. The navigational device may be part of a mobile phone or of an in car navigation system.

Further objects, features, advantages and properties of the method, software product and apparatus according to the invention will become apparent from the detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

In the following detailed portion of the present description, the invention will be explained in more detail with reference to the exemplary embodiments shown in the drawings, in which:

Fig. 1 is a front view of an apparatus according to an embodiment of the invention including a navigation device and skin electrodes, Fig. 2 is a block diagram illustrating the general architecture of the apparatus of Fig. 1,

Fig. 3 is diagrammatic representation of the functions associated with the activation of particular skin electrodes in accordance with an embodiment of the invention,

Fig. 4 is another diagrammatic representation of the functions associated with the activation of particular skin electrodes in accordance with an embodiment of the invention, Fig. 5 is a graph illustrating repeated sequences of electropulse used in an embodiment of the invention, Fig. 6 is a flow chart illustrating a method of communicating navigational instructions to the user according to an embodiment of the invention, Fig. 7 is an elevated view of another embodiment of the apparatus according to the invention,

Fig. 8 is a side view of the apparatus shown in Fig. 7, Fig. 9 is a front view of another embodiment of the invention in which the electrodes are arranged in a car steering and/or in a car steering wheel cover, Fig. 10 is an elevated view of another embodiment of the invention in which the electrodes are arranged in a pair of shoe insoles, and Fig. 12 is a front view of another embodiment of the invention in which the electrodes are arranged in a belt.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

In the following detailed description, the apparatus and the method according to the invention in the form of a personal computer, PDA, mobile terminal or a mobile communication terminal in the form of a cellular/mobile phone will be described by the preferred embodiments.

Fig. 1 illustrates in front view of a first embodiment of an apparatus according to an embodiment of the invention. The system includes two modules (module I and module II) . Module I (external navigation system) includes: a mobile electronic device with GPS and directional sensor. Module II involves a network of skin electrodes connected (wired or wireless) to the module I. The Operation principle of the system is simple and intuitive. Basic components are:

a network (two or more) of skin electrodes placed at user skm/hands/legs/shoulders working synchronously with Module I . Wired or wireless connection (short range BT, T-loop or IR) or just wired

A set of navigation language commands

In the embodiment shown in Fig. 1 Module I is formed by a mobile terminal 1 and Module II is formed by device 100 including skin electrodes.

In an embodiment of the invention the mobile terminal according is in the form of a mobile telephone. The mobile phone 1 comprises a user interface having a housing 2, a display 3, an on/off button (not shown), a speaker 5 (only the opening is shown) , and a microphone 6

(not visible in Fig. 1) . The phone 1 according to the first preferred embodiment is adapted for communication via a cellular network, such as the GSM 900/1800 MHz network, but could just as well be adapted for use with a

Code Division Multiple Access (CDMA) network, a 3G network, or a TCP/IP-based network to cover a possible VoIP-network (e.g. via WLAN, WIMAX or similar) or a mix of VoIP and Cellular such as UMA (Universal Mobile

Access) .

The keypad 7 has a first group of keys 8 as alphanumeric keys, by means of which the user can enter a telephone number, write a text message (SMS) , write a name (associated with the phone number), etc. Each of the twelve alphanumeric keys 8 is provided with a figure "0-9" or a sign "#" or "*", respectively. In alpha mode each key is associated with a number of letters and special signs used in the text editing.

The keypad 2 has additionally a second group of keys comprising two softkeys 9, two call handling keys (offhook key 11 and onhook key 12), and a 5-way navigation key 10 (up, down, left, right and center: select/activate) . The function of the softkeys 9 depends on the state of the phone, and navigation in the menu is performed by using the navigation-key 10. The present function of the softkeys 9 is shown an separate fields (soft labels) in a dedicated area 4 of the display 3, just above the softkeys 9. The two call handling keys 11,12 are used for establishing a call or a conference call, terminating a call or rejecting an incoming call.

The navigation key 10 is a four- or five-way key which can be used for cursor movement, scrolling and selecting (five-way key) and is placed centrally on the front surface of the phone between the display 3 and the group of alphanumeric keys 7.

A releasable rear cover (not shown) gives access to the SIM card (not shown) , and the battery pack (not shown) in the back of tne pnone that supplies electrical power for the electronic components of the mobile phone 1.

The mobile phone 1 has a flat display 3 that is typically made of an LCD with optional back lighting, such as a TFT matrix capable of displaying color images. A touch screen may be used instead of a conventional LCD display.

The mobile phone 1 is provided with a navigation device that includes in an embodiment a GPS receiver. The navigation device in the mobile phone may also be a cellular network based methods such as the cell identification + round trip time or the pilot correlation method. Other systems, such as RF indoor systems can also be used. Details of the navigation device and described further below with reference to Fig. 2.

The device 100 includes a main housing 110 holding electronic circuitry and a battery. The main housing 110 is connected to a left skin electrode 131 via a cable 137 and to a right electrode 132 via cable 138. An extension towards a set of skin electrodes is provided by multiplying the same configuration, e.g. cable ...i... to the electrode ...i.... The arrangement of the electrodes can have different form factors (e.g. suited for a direct attachment to user body or integrated in an external object like a car steering wheel, shoe insole, belt/elastic strip,- etc..)

Fig. 2 illustrates in block diagram form the general architecture of the apparatus 100. The mobile phone 1 includes a processor 18 that controls the operation of the terminal and has an integrated digital signal processor 17 and an integrated RAM 15. The processor 18 controls the communication with the cellular network via the transmitter/receiver circuit 19 and an internal antenna 20. A microphone 6 coupled to the processor 18 via voltage regulators 21 transforms the user's speech into analogue signals, the analogue signals formed thereby are A/D converted in an A/D converter (not shown) before the speech is encoded in the DSP 17 that is included in the processor 18. The encoded speech signal is transferred to the processor 18, which e.g. supports the GSM terminal software. The digital signal-processing unit 17 speech-decodes the signal, which is transferred from the processor 18 to the speaker 5 via a D/A converter (not shown) . Tne voltage regulators 21 form the interface for the speaker 5, the microphone 6, the LED drivers 91 ffnr the LEDS backlighting the keypad 7 and the display 3), the SIM card 22, battery 24, the bottom connector 27, the DC jack 31 (for connecting to the charger 33) and the audio amplifier 32 that drives the (hands-free) loudspeaker 25.

The mobile phone 1 also includes a directional sensor/compass 57 and a GPS receiver 51 that is coupled to a GPS antenna 54.

The processor 18 also forms the interface for some of the peripheral units of the device, including a (Flash) ROM memory 16. the graphical display 3, the keypad 7, a Bluetooth transceiver 26, the GPS receiver 51, the directional sensors/comp us 57, a music player 37 and a music reproduction unit 38.

The device 100 includes a processor 118 that controls the operation of tne device and has an integrated RAM 115 and ROM 116. The processor 118 is coupled to the electrodes 131, 132 and 133, to a battery 124 and to a Bluetooth receiver 126.

Operation

The skin electrode present soft and efficient system directly coupled to user skin (palm, hands, shoulders, back, foot, etc..) The electrodes can operate on two basic principles; e.g. delivering direct voltage stimulation to the user skin nerves (electro-stimulation) or just by vibrations of the skin electrode itself. The skin electrodes can be placed on various suitable positions of the human body or installed in holding/steering external objects like a car steering wheel. In case of direct installment on the human body it can be for instance, left/right hands/legs, shoulders, etc Such placement might be quite natural and in accordance to functional suggestion when/where to turn (left/right/back) . In case of installment on external objects the placement and associated directional meaning of guidance is also natural. For instance activation of the electrodes on the left part of the steering wheel is associated with the meaning "next turn to the LEFT", etc ..

The skin electrodes modules can be placed at different places of user body e.g. shoulders, legs, hands, lets/right parts of stomach or any place depending on user preferences.

Accorαing to an embodiment shown in Fig. 10 the skin electrodes 431,432,431' and 432'are implemented in a cover 410 for a car steering wheel 400 (left skin electrode 431 and right skin electrode 432) and/or at the steering wheel support (left skin electrode 431' and right skin electrode 432' providing possibility to touch it on-demand (e.g. only when navigation info is needed "user is lost" and prior making decision where to go/turn) .

According to an embodiment shown in Fig. 11, the skin electrodes can be integrated in a pair of shoe insoles 501,502 (the foot is extremely sensitive skin area) by placing the left skin electrode 531 on the left insole 501 and placing the right skin electrode on the right insole 502.

The navigational application concepts can be based on a network of 2, 3 or even more skin electrodes. Optimal mode of operation is determined by perceiving sequences of pulsed signals between module I and module II.

The navigational operation uses electro pulsed sequences delivered to the set of skin electrodes 131,132,133 placed at different user body parts or installed at external objects. The most efficient pulse sequences are in range of 0.2 - 2 seconds. Suggested frequencies (F) are in range of F-l-500 Hz (e.g. the operational range where human skin is the most sensitive) .

The electro pulse sequences are composed of two parts; active part with basic frequency (F), time length Tp (cf. Fig. 5) and a "silent part" which does not have any stimulations and which has time length of Ts. For instance Tp-0.4 sec long pulse (F=200 Hz basic frequency) can be followed by Ts-I sec of "silence". Then the whole structure can be repeated several times to ensure perceiving and notification.

Relatively simple directional language can be implemented to guide a user in predetermined direction. For system based on only 2 skin electrodes 131 and 132 turning directions (Left/Right) can be intuitively suggested as shown in Fig 3) . "Go Back" command can be attributed to simultaneous activity of both skin electrodes 131,132 and "Go Forward" command can be default value meaning that forward direction is suggested if there is no activity at any of the skin electrodes. When having 3 (or more) skin electrodes it is possible to distinguish order of subsequent stimulations between the electrodes and attribute it to additional navigational commands. For instance contra-clockwise stimulations can be attributed to UP command and clockwise to DOWN command suggesting out-of-plane movement (meaning: "please one floor up/down in case of indoor navigation conditions").

Time length (Tp, Ts, cf. Fig. 5) of the electro pulsed sequences can be correlated to the relative distance to target (user-target distance) . For instance when user approaches the target the pulses are becoming more frequent (shorter Ts. see Fig 5) .

When a user requests navigation assistance, the processor 18 determines a route with the help of software in a memory of the mobile phone 1 that includes map data. On the base of the signal received from the GPS receiver 51 and from the directional sensor/compass 57 as well as the map data, the processor 18 determines in advance when the user has to make a turn or eventually has to turn around. The navigational instructions generated by the processor 18 may also include height or floor level guidance.

Fig. 3 illustrates the activation of the skin electrodes 131,132 in relation to be navigational instructions issued by the navigation software.

When the navigational software has determined that the user should turn left, the mobile phone 1 sends a corresponding Bluetooth signal which is received by the Bluetooth receiver 126 in the device 100. Upon receipt of the signal in the Bluetooth receiver 126 the processor 118 activates the left skin electrode 131.

When the navigational software has determined that the user should turn right, the right skin electrode 132 is activated via Bluetooth in accordance with the procedure described in detail described here above.

When the navigational software has determined that the user should turn around (go back) the left skin electrode 131 and the right skin electrode 132 are activated simultaneously, via Bluetooth in accordance with the procedure described in detail described here above.

Fig. 4 illustrates the activation of the skin electrodes in another embodiment. In this embodiment there are three skin electrodes: a left skin electrode 131, a right skin electrode 132 and a central or rear electrode 133. In this embodiment the activation of the left or right skin electrode 131,132 when the user nas to turn left or right is exactly as described above. However, when the user has to turn back the rear or middle electrode 131 is activated. Further, when the navigation software has determined that the user should move up, the left, right and rear or middle electrode are activated one after another in an anti-clockwise direction. When the navigational software has determined that the user should move down, the left, right and rear or middle electrode are activated one after another in a clockwise direction.

According to an embodiment, an intuitive mode of operation assumes appropriate navigational suggestions "Where & When & What-WWW" is the next turning point. This operation can be synchronized with the real time movement within and a town map, between buildings, along auto ways, etc. Furthermore, instant WWW navigational service can be requested by user just by pressing the "WWW- emergency button" (not shown) to get immediate navigational info. In a case of integration to external objects like in a car steering wheel user have an option to keep all the time the electrodes in palm (see Fig 10 /right) or touch (by the tombs) the electrodes only when feels "lost" and when guidance is needed "touch on demand") . Such navigation system can provide commodity in many applications like:

Driving a car in unknown area (improved security, not need to move the vision and attention from the road while driving) • When walking in unknown town (silent electro stimuli guide to predefined target)

• Finding other person in crowded occasion and/or large town (service requested by "Find Me - SMS")

• Guiding a customer to selected shop (location aware seiviceb)

Fig. 6 illustrates a flow chart of the method for communicating navigational signals to a user according to an embodiment of the invention. In step 40, the user requests navigation all directions from the mobile electronic device 1. In step 42, the navigational device m the mobile electronic device 1 determines the appropriate route. In step 44 the navigation device monitors present position and heading. In step 46 the navigation device determines that the user should change direction and/or level. In step 48 the navigation device determines which electorate should be activated and sends a signal for activation of the skin electrodes to the apparatus 100. In step 49 the skin electrodes are activated by the apparatus 100. Next, the process returns to step 44 to continue the navigational assistance.

Fig. 7 illustrates another embodiment of the invention that is essentially identical with the embodiments described above, except that the module I and module II are integrated in a single wrist worn device. The wrist worn device 200 includes a housing 201, a display 203, a keypad 207 and a strap 209. As shown in Fig. 8, to skin electrodes 231 and 232 are disposed that the rear side of the housing 201. The operation of the device is similar to the devices described above, with one of the electrodes having the turn left function associated therewith and the other electrode having the turn right function associated therewith. Similarly, activation of both electrodes indicates for the user to turn around. In an embodiment (not shown) there are more than two electrodes disposed on the rear side of the housing 201.

Fig. 9 illustrates another embodiment of the invention, that is essentially identical with the embodiments of Figs. 1 to 6, except that the mobile electronic device is an in car navigation system 300. Module I is included in the in car navigation system 300, which collaborates with an apparatus 100 that is provided with a plurality of skin electrodes (module II) . In the in car navigation system 300 includes a housing 302, a display 303, and a plurality of keys, including a "home" key 310, a mark waypoints key 312, a select key 314 and navigation keys 316,318. The entire navigation system can be attached to a car windscreen with a suction cup (not shown) at the rear of the in car navigation system. In an embodiment the in car navigation system 300 is provided with a Bluetooth receiver that is used for communication with a Bluetooth receiver in another device that forms module II.

Fig. 10 illustrates another embodiment of the invention in form of a car steering wheel cover 420 (or vibration surfaces) to guide/suggest the driver where to turn/go. The skin electrodes can be realized in a form of the wheel cover/coat 420 where the electrodes 431, 432, 431' , 432' are placed on left/right side of the wheel. While driving a car user holds the wheel and feels guidance suggestions where to turn on the next cross point/square. The navigational info is received prior the turning point. In an embodiment the electrodes 432', 432' are placed on tho wheel support. If not sure where to go the driver may touch both electrodes (by the thumbs) and feel a suggestion where to go. Notice that such approach offers "alternative suggestion" preventing user of not necessary guiding suggestion (touch-on-demand) .

Fig. 12 illustrates another embodiment in which the rear/central electrode 633, the left electrode 631 and the right to electrodes 632 electrodes are placed on the inside a belt/elastic strip 600. In all cases the electrodes are in close contact with user skin. The operational principle is the same as described in previous solutions .

The invention can be used for:

• Tourist guidance (museums, theatres, shops, etc ) • Various location aware applications / information and services

• Running in forest and do not get lost

• Health, Sport and Fitness

• Silent communication equipment Post office delivery and E-guidance to address.

The invention has numerous advantages. Different embodiments or implementations may yield one or more of the following advantages. It should be noted that this is not an exhaustive list and there may be other advantages which are not described herein. One advantage of the invention is that a new communication dimension (synchronized electro stimuli for navigation) is added to existing user interfaces. Another advantage of the present invention is the ultra low power consumption of electrodes (months instead of weeks with a small battery when compared with vibra-based systems). Yet another advantage of the present invention is the intuitive nature of the communication of the navigational signals. Another advantage of the present invention is the low disturbance of the direct environment, the independency from audio-visual conditions, and the very silent and "non-visible" communication. Yet another advantage of the pLesern: invention is the provision of a new communication language & protocols. Another advantage of the invention is the possibility for language customization (by user) . Yet another advantage of the invention is the possibility for useful, silent and not disturbing information to guide a user in real 3D space and in accordance with his/her predefined program/target (digital services).

The term "comprising" as used in the claims does not exclude other elements or steps. The term "a" or "an" as used in the claims does not exclude a plurality. The single processor or other unit may fulfill the functions of several means recited in the claims. Although the present invention has been described in detail for purpose of illustration, it is understood that such detail is solely for that purpose, and variations can be made therein by those skilled in the art without departing from the scope of the invention.

Claims

CLAIMS :

1. A method for directing a user with a navigational device, the navigational device being operatively coupled to at least two skin electrodes comprising:

placing the at least two skin electrodes on the skin of the user, generating navigational directions for user, converting the navigational directions to signals for activating the electrodes.

2. A method according to claim 1, wherein one of the at least two skin electrodes is placed or touched on or by the left side of the body of the user and the other of the at least two electrodes is placed/touched on/by the right side of the body of the user.

3. A method according to claim 2, further comprising activating the skin electrode placed on the left side of the body when the navigational directions indicate that the user should turn left and activating the skin electrodes placed on the right side of the body when the navigational directions indicate that the user should turn right.

4. A method according to claim 2, further comprising activating the left skin electrode and the right skin electrode simultaneously when the navigational and directions indicate that the user should turn around.

5. A method according to claim 2 or 3, further comprising a third skin electrode, the third electrode preferably being placed in the middle and/or on the back of the body of the user.

6. A method according to claim 5, further comprising activating the third electrode when the navigational directions indicate that the user should turn back.

7. A method according to any of claims 1 to 6, further comprising activating the electrodes in a predetermined sequence.

8. A method according to claim 7, comprising a plurality of different sequences, each having a different meaning associated therewith.

9. A method according to any of claims 1 to 8, wherein the activation of any of the skin electrodes includes the use of electro-pulse sequences.

10. A method according to claim 9, wherein the electropulse sequences are composed of two parts, and an active part with a basic frequency, time length and a silent partner free of stimulations with another predetermined time length.

11. A method according to claim 10, wherein an activation of any of the skin electrodes includes a plurality of the two parts.

12. A software program product executing the method according to any of claims 1 to 11 when run on a processor.

13 An apparatus comprising a navigation device operatively coupled to two or more skin electrodes, the navigation device being configured to generate navigational instructions in the form of activation signals for the one more skin electrodes.

14. An apparatus according to claim 13, wherein the navigational device generates navigational instructions for a user, and the navigational device is configured to activate one or more of the electrodes when the navigational instructions indicate that the user needs to change direction.

15. An apparatus armrding to claim 14, wherein the apparatus comprises a left skin electrode and a right skin electrode, the navigational device is configured to activate the left skin electrode when the navigational instructions indicate that the user needs to turn left, and the navigational device is configured to activate the a right skin electrode when the navigational instructions indicate that the user needs to turn right.

16. An apparatus according to claim 14 or 15, wherein the apparatus comprises a central or rear skin electrode, the navigational device is configured to activate the central or rear skin electrode when the navigational instructions indicate that the user needs to turn around.

17. An apparatus according to any of claims 13 to 16, wherein the navigational device is configured to generate a sequence of activations of any of the electrodes when they navigational instructions indicate that the user needs to change direction.

18. An apparatus according to claim 17, wherein the navigational device is configured to activate the left to electrode, the right to electrode and the middle or rear electrode sequentially when the navigational instructions indicate that the user needs to change level.

19. An apparatus according to any of claims 13 to 18, wherein the navigational device and the electrodes are connected by wires.

20. An apparatus according to any of claims 13 to 18, wherein the navigational device and the electrodes are wirelessly connected.

21. An apparatus according to any of claims 13 to 20, wherein the navigational device comprises a position detector and map data.

22. An apparatus according to any of claims 13 to 21, wherein navigational device is configured to activate the left skin electrode and the right skin electrode simultaneously when the navigational instructions indicate that the user needs to turn around.

23. An apparatus according to claim 21, wherein the navigational device comprises a processor configured to determine a route based on user instructions, position data that and map data.

24. An apparatus according to any of claims 13 to 20, wherein the navigational device receives its position and map data from a remote server via a wireless connection.

25. An apparatus according to any of claims 13 to 24, wherein the navigational device is part of a mobile phone or of an in car navigation system.

26 A software product for use in a mobile electronic apparatus that is provided with a navigation device, the software product comprising:

software code for generating signals for activating skin electrodes corresponding to navigational instructions received from the navigation device.