WO2010081538A2

WO2010081538A2 - Navigation device & method

Info

Publication number: WO2010081538A2
Application number: PCT/EP2009/050358
Authority: WO
Inventors: Sjoerd Aben; Pieter Geelen
Original assignee: Tomtom International B.V.
Priority date: 2009-01-14
Filing date: 2009-01-14
Publication date: 2010-07-22
Also published as: WO2010081538A3

Abstract

This invention relates to a navigation device (200) comprising a processor (210), a store (230) for map data, means (322) to access one or more types of additional information for use in route computation and a multiple route computation module (490) arranged to determine a first route from a start location to a destination location using the map data and one or more types of additional information and to determine one or more additional routes using the map data and fewer, or different, types of additional information from the first route.

Description

NAVIGATION DEVICE & METHOD

Field of the Invention

This invention relates to navigation devices and to methods for displaying navigation maps. Illustrative embodiments of the invention relate to portable navigation devices (so-called PNDs), in particular PNDs that include Global Positioning System (GPS) signal reception and processing functionality. Other embodiments relate, more generally, to any type of processing device that is configured to execute navigation software so as to provide route planning, and preferably also navigation, functionality.

Background to the Invention

Portable navigation devices (PNDs) that include GPS (Global Positioning System) signal reception and processing functionality are well known and are widely employed as in-car or other vehicle navigation systems. In general terms, a modern PNDs comprises a processor, memory (at least one of volatile and non-volatile, and commonly both), and map data stored within said memory. The processor and memory cooperate to provide an execution environment in which a software operating system may be established, and additionally it is commonplace for one or more additional software programs to be provided to enable the functionality of the PND to be controlled, and to provide various other functions.

Typically these devices further comprise one or more input interfaces that allow a user to interact with and control the device, and one or more output interfaces by means of which information may be relayed to the user. Illustrative examples of output interfaces include a visual display and a speaker for audible output. Illustrative examples of input interfaces include one or more physical buttons to control on/off operation or other features of the device (which buttons need not necessarily be on the device itself but could be on a steering wheel if the device is built into a vehicle), and a microphone for detecting user speech. In a particularly preferred arrangement the output interface display may be configured as a touch sensitive display (by means of a touch sensitive overlay or otherwise) to additionally provide an input interface by means of which a user can operate the device by touch.

Devices of this type will also often include one or more physical connector interfaces by means of which power and optionally data signals can be transmitted to and received from the device, and optionally one or more wireless transmitters/receivers to allow communication over cellular telecommunications and other signal and data networks, for example Wi-Fi, Wi-Max GSM and the like. PND devices of this type also include a GPS antenna by means of which satellite-broadcast signals, including location data, can be received and subsequently processed to determine a current location of the device.

The PND device may also include electronic gyroscopes and accelerometers which produce signals that can be processed to determine the current angular and linear acceleration, and in turn, and in conjunction with location information derived from the GPS signal, velocity and relative displacement of the device and thus the vehicle in which it is mounted. Typically such features are most commonly provided in in-vehicle navigation systems, but may also be provided in PND devices if it is expedient to do so. The utility of such PNDs is manifested primarily in their ability to determine a route between a first location (typically a start or current location) and a second location (typically a destination). These locations can be input by a user of the device, by any of a wide variety of different methods, for example by postcode, street name and house number, previously stored "well known" destinations (such as famous locations, municipal locations (such as sports grounds or swimming baths) or other points of interest), and favourite or recently visited destinations.

Typically, the PND is enabled by software for computing a "best" or "optimum" route between the start and destination address locations from the map data. A "best" or "optimum" route is determined on the basis of predetermined criteria and need not necessarily be the fastest or shortest route. The selection of the route along which to guide the driver can be very sophisticated, and the selected route may take into account existing, predicted and dynamically and/or wirelessly received traffic and road information, historical information about road speeds, and the driver's own preferences for the factors determining road choice (for example the driver may specify that the route should not include motorways or toll roads).

In addition, the device may continually monitor road and traffic conditions, and offer to or choose to change the route over which the remainder of the journey is to be made due to changed conditions. Real time traffic monitoring systems, based on various technologies (e.g. mobile phone data exchanges, fixed cameras, GPS fleet tracking) are being used to identify traffic delays and to feed the information into notification systems.

PNDs of this type may typically be mounted on the dashboard or windscreen of a vehicle, but may also be formed as part of an on-board computer of the vehicle radio or indeed as part of the control system of the vehicle itself. The navigation device may also be part of a hand-held system, such as a PDA (Portable Digital Assistant) a media player, a mobile phone or the like, and in these cases, the normal functionality of the hand-held system is extended by means of the installation of software on the device to perform both route calculation and navigation along a calculated route.

Route planning and navigation functionality may also be provided by a desktop or mobile computing resource running appropriate software. For example, the Royal Automobile Club (RAC) provides an on-line route planning and navigation facility at http://www.rac.co.uk, which facility allows a user to enter a start point and a destination whereupon the server to which the user's PC is connected calculates a route (aspects of which may be user specified), generates a map, and generates a set of exhaustive navigation instructions for guiding the user from the selected start point to the selected destination. The facility also provides for pseudo three-dimensional rendering of a calculated route, and route preview functionality which simulates a user travelling along the route and thereby provides the user with a preview of the calculated route.

In the context of a PND, once a route has been calculated, the user interacts with the navigation device to select the desired calculated route, optionally from a list of proposed routes. Optionally, the user may intervene in, or guide the route selection process, for example by specifying that certain routes, roads, locations or criteria are to be avoided or are mandatory for a particular journey. The route calculation aspect of the PND forms one primary function, and navigation along such a route is another primary function.

During navigation along a calculated route, it is usual for such PNDs to provide visual and/or audible instructions to guide the user along a chosen route to the end of that route, i.e. the desired destination. It is also usual for PNDs to display map information on-screen during the navigation, such information regularly being updated on-screen so that the map information displayed is representative of the current location of the device, and thus of the user or user's vehicle if the device is being used for in- vehicle navigation.

An icon displayed on-screen typically denotes the current device location, and is centred with the map information of current and surrounding roads in the vicinity of the current device location and other map features also being displayed. Additionally, navigation information may be displayed, optionally in a status bar above, below or to one side of the displayed map information, examples of navigation information include a distance to the next deviation from the current road required to be taken by the user, the nature of that deviation possibly being represented by a further icon suggestive of the particular type of deviation, for example a left or right turn. The navigation function also determines the content, duration and timing of audible instructions by means of which the user can be guided along the route. As can be appreciated a simple instruction such as "turn left in 100 m" requires significant processing and analysis. As previously mentioned, user interaction with the device may be by a touch screen, or additionally or alternately by steering column mounted remote control, by voice activation or by any other suitable method.

A further important function provided by the device is automatic route re- calculation in the event that: a user deviates from the previously calculated route during navigation (either by accident or intentionally); real-time traffic conditions dictate that an alternative route would be more expedient and the device is suitably enabled to recognize such conditions automatically, or if a user actively causes the device to perform route re-calculation for any reason. It is also known to allow a route to be calculated with user defined criteria; for example, the user may prefer a scenic route to be calculated by the device, or may wish to avoid any roads on which traffic congestion is likely, expected or currently prevailing. The device software would then calculate various routes and weigh more favourably those that include along their route the highest number of points of interest (known as POIs) tagged as being for example of scenic beauty, or, using stored information indicative of prevailing traffic conditions on particular roads, order the calculated routes in terms of a level of likely congestion or delay on account thereof. Other POI-based and traffic information-based route calculation and navigation criteria are also possible.

Although the route calculation and navigation functions are fundamental to the overall utility of PNDs, it is possible to use the device purely for information display, or "free-driving", in which only map information relevant to the current device location is displayed, and in which no route has been calculated and no navigation is currently being performed by the device. Such a mode of operation is often applicable when the user already knows the route along which it is desired to travel and does not require navigation assistance.

Devices of the type described above, for example the 720T model manufactured and supplied by TomTom International B. V., provide a reliable means for enabling users to navigate from one position to another.

However, a problem arises in that a route selected by a PND may not always be acceptable to a user. For example, when selecting a route between start and destination address locations, the PND may take into account traffic information and select a route which avoids roads currently experiencing a high traffic volume or currently carrying traffic with a low average speed. However, a user may not be aware that those roads have been avoided and may attempt to repeat the journey on another occasion by following the previously selected route, which may not be the best route on that occasion. It is an aim of the present invention to address this problem, in particular to attempt to provide a user with more information concerning route selection.

Summary of the Invention In pursuit of this aim, a presently preferred embodiment of the present invention provides a navigation device comprising: a processor; a store for map data; and means to access one or more types of additional information for use in route computation; characterised in that the navigation device further comprises: a multiple route computation module arranged to determine a first route from a start location to a destination location using the map data at least one or more types of additional information and to determine one ore more additional routes using the map data and fewer, or different, types of additional information from the first route

Another embodiment of the present invention relates to a method of method of route calculation for use in a navigation apparatus, the method comprising the steps of: determining a first route from a start location to a destination location using map data and at least one type of additional information; determining a second route from the start location to the destination location using the map data and either fewer or different types of additional information than the first route.

Yet another embodiment of the present invention relates to computer software comprising one or more software modules operable, when executed in an execution environment, to cause a processor to perform a method of method of route calculation for use in a navigation apparatus, the method comprising the steps of: determining a first route from a start location to a destination location using map data and at least one type of additional information; determining a second route from the start location to the destination location using the map data and either fewer or different types of additional information than the first route.

Advantages of these embodiments are set out hereafter, and further details and features of each of these embodiments are defined in the accompanying dependent claims and elsewhere in the following detailed description.

Brief Description of the Drawings

Various aspects of the teachings of the present invention, and arrangements embodying those teachings, will hereafter be described by way of illustrative example with reference to the accompanying drawings, in which: Fig. 1 is a schematic illustration of a Global Positioning System (GPS);

Fig. 2 is a schematic illustration of electronic components arranged to provide a navigation device;

Fig. 3 is a schematic illustration of the manner in which a navigation device may receive information over a wireless communication channel;

Figs. 4A and 4B are illustrative perspective views of a navigation device; Fig. 5 is a schematic representation of the software employed by the navigation device;

Fig. 6 is an illustration of map data; and

Figure 7 is a further illustration of map data.

Detailed Description of Preferred Embodiments

Preferred embodiments of the present invention will now be described with particular reference to a PND. It should be remembered, however, that the teachings of the present invention are not limited to PNDs but are instead universally applicable to any type of processing device that is configured to execute navigation software so as to provide route planning and navigation functionality. It follows therefore that in the context of the present application, a navigation device is intended to include (without limitation) any type of route planning and navigation device, irrespective of whether that device is embodied as a PND, a navigation device built into a vehicle, or indeed a computing resource (such as a desktop or portable personal computer (PC), mobile telephone or portable digital assistant (PDA)) executing route planning and navigation software.

It will also be apparent from the following that the teachings of the present invention even have utility in circumstances where a user is not seeking instructions on how to navigate from one point to another, but merely wishes to be provided with a view of a given location. In such circumstances the "destination" location selected by the user need not have a corresponding start location from which the user wishes to start navigating, and as a consequence references herein to the "destination" location or indeed to a "destination" view should not be interpreted to mean that the generation of a route is essential, that travelling to the "destination" must occur, or indeed that the presence of a destination requires the designation of a corresponding start location.

With the above provisos in mind, Fig. 1 illustrates an example view of Global Positioning System (GPS), usable by navigation devices. Such systems are known and are used for a variety of purposes. In general, GPS is a satellite-radio based navigation system capable of determining continuous position, velocity, time, and in some instances direction information for an unlimited number of users. Formerly known as NAVSTAR, the GPS incorporates a plurality of satellites which orbit the earth in extremely precise orbits. Based on these precise orbits, GPS satellites can relay their location to any number of receiving units.

The GPS system is implemented when a device, specially equipped to receive GPS data, begins scanning radio frequencies for GPS satellite signals. Upon receiving a radio signal from a GPS satellite, the device determines the precise location of that satellite via one of a plurality of different conventional methods. The device will continue scanning, in most instances, for signals until it has acquired at least three different satellite signals (noting that position is not normally, but can be determined, with only two signals using other triangulation techniques). Implementing geometric triangulation, the receiver utilizes the three known positions to determine its own two-dimensional position relative to the satellites. This can be done in a known manner. Additionally, acquiring a fourth satellite signal will allow the receiving device to calculate its three dimensional position by the same geometrical calculation in a known manner. The position and velocity data can be updated in real time on a continuous basis by an unlimited number of users.

As shown in Figure 1 , the GPS system is denoted generally by reference numeral 100. A plurality of satellites 120 are in orbit about the earth 124. The orbit of each satellite 120 is not necessarily synchronous with the orbits of other satellites 120 and, in fact, is likely asynchronous. A GPS receiver 140 is shown receiving spread spectrum GPS satellite signals 160 from the various satellites 120.

The spread spectrum signals 160, continuously transmitted from each satellite 120, utilize a highly accurate frequency standard accomplished with an extremely accurate atomic clock. Each satellite 120, as part of its data signal transmission 160, transmits a data stream indicative of that particular satellite 120. It is appreciated by those skilled in the relevant art that the GPS receiver device 140 generally acquires spread spectrum GPS satellite signals 160 from at least three satellites 120 for the GPS receiver device 140 to calculate its two-dimensional position by triangulation. Acquisition of an additional signal, resulting in signals 160 from a total of four satellites 120, permits the GPS receiver device 140 to calculate its three-dimensional position in a known manner.

Figure 2 is an illustrative representation of electronic components of a navigation device 200 according to a preferred embodiment of the present invention, in block component format. It should be noted that the block diagram of the navigation device 200 is not inclusive of all components of the navigation device, but is only representative of many example components.

The navigation device 200 is located within a housing (not shown). The housing includes a processor 210 connected to an input device 220 and a display screen 240. The input device 220 can include a keyboard device, voice input device, touch panel and/or any other known input device utilised to input information; and the display screen 240 can include any type of display screen such as an LCD display, for example. In a particularly preferred arrangement the input device 220 and display screen 240 are integrated into an integrated input and display device, including a touchpad or touchscreen input so that a user need only touch a portion of the display screen 240 to select one of a plurality of display choices or to activate one of a plurality of virtual buttons. The navigation device may include an output device 260, for example an audible output device (e.g. a loudspeaker). As output device 260 can produce audible information for a user of the navigation device 200, it is should equally be understood that input device 240 can include a microphone and software for receiving input voice commands as well. In the navigation device 200, processor 210 is operatively connected to and set to receive input information from input device 220 via a connection 225, and operatively connected to at least one of display screen 240 and output device 260, via output connections 245, to output information thereto. Further, the processor 210 is operably coupled to a memory resource 230 via connection 235 and is further adapted to receive/send information from/to input/output (I/O) ports 270 via connection 275, wherein the I/O port 270 is connectible to an I/O device 280 external to the navigation device 200. The memory resource 230 comprises, for example, a volatile memory, such as a Random Access Memory (RAM) and a non-volatile memory, for example a digital memory, such as a flash memory. The external I/O device 280 may include, but is not limited to an external listening device such as an earpiece for example. The connection to I/O device 280 can further be a wired or wireless connection to any other external device such as a car stereo unit for hands-free operation and/or for voice activated operation for example, for connection to an ear piece or head phones, and/or for connection to a mobile phone for example, wherein the mobile phone connection may be used to establish a data connection between the navigation device 200 and the internet or any other network for example, and/or to establish a connection to a server via the internet or some other network for example.

Fig. 2 further illustrates an operative connection between the processor 210 and an antenna/receiver 250 via connection 255, wherein the antenna/receiver 250 can be a GPS antenna/receiver for example. It will be understood that the antenna and receiver designated by reference numeral 250 are combined schematically for illustration, but that the antenna and receiver may be separately located components, and that the antenna may be a GPS patch antenna or helical antenna for example.

Further, it will be understood by one of ordinary skill in the art that the electronic components shown in Fig. 2 are powered by power sources (not shown) in a conventional manner. As will be understood by one of ordinary skill in the art, different configurations of the components shown in Fig. 2 are considered to be within the scope of the present application. For example, the components shown in Fig. 2 may be in communication with one another via wired and/or wireless connections and the like. Thus, the scope of the navigation device 200 of the present application includes a portable or handheld navigation device 200.

In addition, the portable or handheld navigation device 200 of Fig. 2 can be connected or "docked" in a known manner to a vehicle such as a bicycle, a motorbike, a car or a boat for example. Such a navigation device 200 is then removable from the docked location for portable or handheld navigation use. Referring now to Fig. 3, the navigation device 200 may establish a "mobile" or telecommunications network connection with a server 302 via a mobile device (not shown) (such as a mobile phone, PDA, and/or any device with mobile phone technology) establishing a digital connection (such as a digital connection via known Bluetooth technology for example). Thereafter, through its network service provider, the mobile device can establish a network connection (through the internet for example) with a server 302. As such, a "mobile" network connection is established between the navigation device 200 (which can be, and often times is mobile as it travels alone and/or in a vehicle) and the server 302 to provide a "real-time" or at least very "up to date" gateway for information. The establishing of the network connection between the mobile device (via a service provider) and another device such as the server 302, using an internet (such as the World Wide Web) for example, can be done in a known manner. This can include use of TCP/IP layered protocol for example. The mobile device can utilize any number of communication standards such as CDMA, GSM, WAN, etc. As such, an internet connection may be utilised which is achieved via data connection, via a mobile phone or mobile phone technology within the navigation device 200 for example. For this connection, an internet connection between the server 302 and the navigation device 200 is established. This can be done, for example, through a mobile phone or other mobile device and a GPRS (General Packet Radio Service)- connection (GPRS connection is a high-speed data connection for mobile devices provided by telecom operators; GPRS is a method to connect to the internet). The navigation device 200 can further complete a data connection with the mobile device, and eventually with the internet and server 302, via existing Bluetooth technology for example, in a known manner, wherein the data protocol can utilize any number of standards, such as the GSRM, the Data Protocol Standard for the GSM standard, for example.

The navigation device 200 may include its own mobile phone technology within the navigation device 200 itself (including an antenna for example, or optionally using the internal antenna of the navigation device 200). The mobile phone technology within the navigation device 200 can include internal components as specified above, and/or can include an insertable card (e.g. Subscriber Identity Module or SIM card), complete with necessary mobile phone technology and/or an antenna for example. As such, mobile phone technology within the navigation device 200 can similarly establish a network connection between the navigation device 200 and the server 302, via the internet for example, in a manner similar to that of any mobile device. For GRPS phone settings, a Bluetooth enabled navigation device may be used to correctly work with the ever changing spectrum of mobile phone models, manufacturers, etc., model/manufacturer specific settings may be stored on the navigation device 200 for example. The data stored for this information can be updated.

In Fig. 3 the navigation device 200 is depicted as being in communication with the server 302 via a generic communications channel 318 that can be implemented by any of a number of different arrangements. The server 302 and a navigation device 200 can communicate when a connection via communications channel 318 is established between the server 302 and the navigation device 200 (noting that such a connection can be a data connection via mobile device, a direct connection via personal computer via the internet, etc.).

The server 302 includes, in addition to other components which may not be illustrated, a processor 304 operatively connected to a memory 306 and further operatively connected, via a wired or wireless connection 314, to a mass data storage device 312. The processor 304 is further operatively connected to transmitter 308 and receiver 310, to transmit and send information to and from navigation device 200 via communications channel 318. The signals sent and received may include data, communication, and/or other propagated signals. The transmitter 308 and receiver 310 may be selected or designed according to the communications requirement and communication technology used in the communication design for the navigation system 200. Further, it should be noted that the functions of transmitter 308 and receiver 310 may be combined into a signal transceiver. Server 302 is further connected to (or includes) a mass storage device 312, noting that the mass storage device 312 may be coupled to the server 302 via communication link 314. The mass storage device 312 contains a store of navigation data and map information, and can again be a separate device from the server 302 or can be incorporated into the server 302.

The navigation device 200 is adapted to communicate with the server 302 through communications channel 318, and includes processor, memory, etc. as previously described with regard to Fig. 2, as well as transmitter 320 and receiver 322 to send and receive signals and/or data through the communications channel 318, noting that these devices can further be used to communicate with devices other than server 302. Further, the transmitter 320 and receiver 322 are selected or designed according to communication requirements and communication technology used in the communication design for the navigation device 200 and the functions of the transmitter 320 and receiver 322 may be combined into a single transceiver. Software stored in server memory 306 provides instructions for the processor

304 and allows the server 302 to provide services to the navigation device 200. One service provided by the server 302 involves processing requests from the navigation device 200 and transmitting navigation data from the mass data storage 312 to the navigation device 200. Another service provided by the server 302 includes processing the navigation data using various algorithms for a desired application and sending the results of these calculations to the navigation device 200.

The communication channel 318 generically represents the propagating medium or path that connects the navigation device 200 and the server 302. Both the server 302 and navigation device 200 include a transmitter for transmitting data through the communication channel and a receiver for receiving data that has been transmitted through the communication channel.

The communication channel 318 is not limited to a particular communication technology. Additionally, the communication channel 318 is not limited to a single communication technology; that is, the channel 318 may include several communication links that use a variety of technology. For example, the communication channel 318 can be adapted to provide a path for electrical, optical, and/or electromagnetic communications, etc. As such, the communication channel 318 includes, but is not limited to, one or a combination of the following: electric circuits, electrical conductors such as wires and coaxial cables, fibre optic cables, converters, radio-frequency (RF) waves, the atmosphere, empty space, etc. Furthermore, the communication channel 318 can include intermediate devices such as routers, repeaters, buffers, transmitters, and receivers, for example.

In one illustrative arrangement, the communication channel 318 includes telephone and computer networks. Furthermore, the communication channel 318 may be capable of accommodating wireless communication such as radio frequency, microwave frequency, infrared communication, etc. Additionally, the communication channel 318 can accommodate satellite communication.

The communication signals transmitted through the communication channel 318 include, but are not limited to, signals as may be required or desired for given communication technology. For example, the signals may be adapted to be used in cellular communication technology such as Time Division Multiple Access (TDMA), Frequency Division Multiple Access (FDMA), Code Division Multiple Access (CDMA), Global System for Mobile Communications (GSM), etc. Both digital and analogue signals can be transmitted through the communication channel 318. These signals may be modulated, encrypted and/or compressed signals as may be desirable for the communication technology.

The server 302 includes a remote server accessible by the navigation device 200 via a wireless channel. The server 302 may include a network server located on a local area network (LAN), wide area network (WAN), virtual private network (VPN), etc.

The server 302 may include a personal computer such as a desktop or laptop computer, and the communication channel 318 may be a cable connected between the personal computer and the navigation device 200. Alternatively, a personal computer may be connected between the navigation device 200 and the server 302 to establish an internet connection between the server 302 and the navigation device 200. Alternatively, a mobile telephone or other handheld device may establish a wireless connection to the internet, for connecting the navigation device 200 to the server 302 via the internet.

The navigation device 200 may be provided with information from the server 302 via information downloads which may be periodically updated automatically or upon a user connecting navigation device 200 to the server 302 and/or may be more dynamic upon a more constant or frequent connection being made between the server 302 and navigation device 200 via a wireless mobile connection device and TCP/IP connection for example. For many dynamic calculations, the processor 304 in the server 302 may be used to handle the bulk of the processing needs, however, processor 210 of navigation device 200 can also handle much processing and calculation, oftentimes independent of a connection to a server 302.

As indicated above in Fig. 2, a navigation device 200 includes a processor 210, an input device 220, and a display screen 240. The input device 220 and display screen 240 are integrated into an integrated input and display device to enable both input of information (via direct input, menu selection, etc.) and display of information through a touch panel screen, for example. Such a screen may be a touch input LCD screen, for example, as is well known to those of ordinary skill in the art. Further, the navigation device 200 can also include any additional input device 220 and/or any additional output device 241 , such as audio input/output devices for example.

Figs 4A and 4B are perspective views of a navigation device 200. As shown in Fig. 4A, the navigation device 200 may be a unit that includes an integrated input and display device 290 (a touch panel screen for example) and the other components of fig. 2 (including but not limited to internal GPS receiver 250, microprocessor 210, a power supply, memory systems 230, etc.).

The navigation device 200 may sit on an arm 292, which itself may be secured to a vehicle dashboard/window/etc, using a suction cup 294. This arm 292 is one example of a docking station to which the navigation device 200 can be docked.

As shown in Fig. 4B, the navigation device 200 can be docked or otherwise connected to an arm 292 of the docking station by snap connecting the navigation device 292 to the arm 292 for example. The navigation device 200 may then be rotatable on the arm 292, as shown by the arrow of Fig. 4B. To release the connection between the navigation device 200 and the docking station, a button on the navigation device 200 may be pressed, for example. Other equally suitable arrangements for coupling and decoupling the navigation device to a docking station are well known to persons of ordinary skill in the art.

Referring now to Fig. 5 of the accompanying drawings, the memory resource 230 stores a boot loader program (not shown) that is executed by the processor 210 in order to load an operating system 470 from the memory resource 230 for execution by functional hardware components 460, which provides an environment in which application software 480 can run. The operating system 470 serves to control the functional hardware components 460 and resides between the application software 480 and the functional hardware components 460. The application software 480 provides an operational environment including the GUI that supports core functions of the navigation device 200, for example map viewing, route planning, navigation functions and any other functions associated therewith. In accordance with the preferred embodiment of the present invention, part of this functionality comprises a multiple route calculation module 490, the function of which will now be described in detail in connection with the following figures. As discussed above, part of the application software 480 is arranged for computing a "best" or "optimum" route between start and destination address locations from map data stored in the memory 230. A "best" or "optimum" route is determined on the basis of predetermined criteria, such as user preferences etc. The map data typically comprises a plurality of nodes and segments linking those nodes. Nodes and segments may have associated attributes, such as speed limits, road type indications etc. Using the map information, including the associated attributes, the "best" route is computed between the start and destination addresses on the basis of the predetermined criteria, such as the route being the "fastest" (minimum time), "shortest" (least distance), avoiding certain road types e.g. motorways, or other criteria.

A method of route computation will now be described with reference to Figure 6. Figure 6 shows an illustration of map data which contains nodes A-G, representing places, linked by segments 601 -609 representing roads. When executing the application software 480, the processor 210 is arranged to compute a route between node A as the start location and node G as the destination location. In this example, the processor 210 is configured to compute a fastest route between the nodes A and G. In order to compute the route, the processor 210 refers to speed limit and/or road type attribute information associated with the segments in the map data to compute the fastest route. The processor 210 computes the fastest route to include segment 602 linking nodes A and D. At node D, there exist two candidate routes. The first travels through nodes E and F to G, whilst the second travels directly to node G. The map data indicates that segment 608 linking nodes D and G has a greater length than a sum of segments 605, 606, 607 linking nodes D, E, F, G. However, the attribute information indicates that segment 608 has a greater speed limit than segments 605, 606, 607, for example segment 608 is a bypass road having a relatively high speed limit, whereas segments 605, 606, 607 are urban roads having a relatively low speed limit. Therefore, the processor 210 determines that the fastest route from A to G includes segments 602 and 608.

However, the application software 480 executing on processor 210 may also consider additional information, such as dynamically received traffic information, when computing the route between nodes A and G. For example, the navigation device 200 may receive wirelessly broadcast traffic information using an RDS-TMC receiver. In an example situation, at the time of the processor 210 computing the route between nodes A and G, the received traffic information may indicate that the segment 608 linking nodes D and G has a very low average speed due to an accident. In this case, the processor 210 would compute the fastest route between nodes A and G as including segments 605, 606, 607. As the user would be unaware that the computed route had not included segment 608, they may believe that the fastest route between A and G always included segments 605, 606, 607. Alternatively, the user may know that segment 608 is a road well serviced by emergency services/recovery vehicles and that the accident will be cleared relatively quickly, in which case the user may wish to join the traffic on segment 608 since the user believes that the traffic situation on segment 608 will rapidly improve.

In order to alleviate these problems, the multiple route calculation module 490 is arranged to determine a plurality of routes between the start and destination addresses. The multiple route calculation module 490 is arranged to cause the processor 210 to compute a plurality of routes, each using differing types and/or amounts of additional information. In one embodiment, a first route is computed using the map data stored in memory 230 and all available additional information, such as traffic information, historic traffic information, road condition information, toll road information etc. The first route is likely to be a "best" route meeting the user's predetermined criteria at the time the route is computed. For example, the first route is likely to be the fastest route at that time which avoids traffic delays indicated in the traffic information. In addition to the first route, the multiple route calculation module 490 causes the processor 210 to determine at least one additional route which does not take into account at least some of the additional information. In some embodiments, the processor 210 is arranged to compute a second route which only takes into account the map data i.e. does not consider any additional information. In this case, the first route would be the best route at the time of route planning, whereas the second route would the theoretically fastest route, i.e. according to the map data, at other times. The processor 210 may compute a third route additional to the first route but either alternatively or additionally to the second route, which only takes into account some of the additional information, or takes into account different additional information. The third route may, for example, not take into account traffic information but may consider toll road information indicating on which roads a toll is required to be paid, road condition information, historic journey information relating to recorded journeys made along segments and/or any other information additional to the map data. Further routes may also be computed by the multiple route calculation module which, for example, consider other additional information.

Example operation of the multiple route calculation module 490 will now be explained with reference to Figure 7. Figure 7 illustrates example map data comprising nodes A-G and segments 701 -

710 indicating roads linking those segments, as shown. By way of an example, the processor 210 is caused by the multiple route calculation module 490 to compute a route between a start node A and a destination node G. The processor 210 is caused by the multiple route calculation module 490 to compute a first route from node A to node G using all information available to the navigation device 200. The available additional information is summarised in the table below.

Using the additional information above, the processor 210 is arranged to compute the first route between nodes A and G as being via segments 701 , 706 and 710, thereby avoiding segment 705 which currently has a low average speed due to an accident, segment 707 having a low average speed due to flooding and segment 708 on which a toll is payable. The processor 210 then computes a second route using less additional information than the first route. By way of example, the second route is computed using no additional information, only the map data stored in the memory 230. The second route is computed by the processor 210 to include segments 702, 705 and 709. It will be noted however that the second route may have been computed using some, but not all, additional information. For example, the second route may be computed using traffic information, but not road condition information or toll information. In this case, the second route would comprise segments 702, 704, 707 and 709. The multiple route calculation module 490 may cause the processor 210 to compute one or more additional routes using other combinations, amounts or types of additional information. For example, a third route may be computed using road condition information but not traffic information.

In some cases, the first and second routes, and any further computed routes, will be identical. In these cases, the multiple route calculation module 490 causes the processor 210 to provide route guidance to the user along the computed route. However, if the computed routes differ, one embodiment of the present invention provides an indication of the different routes to the user. For example, the navigation device 200 may display an indication to the user on the display device 240 that multiple routes have been determined. The indication may comprise information identifying a difference between the routes, or information indicating each of the routes. For example, referring to Figure 7, the navigation device 200 may indicate that first and second routes have been determined, the first route comprising segments 701 , 706 and 710, and a second route comprising segments 702, 704, 707 and 709. The indication may further comprise information such as an estimated journey time and/or information identifying why the routes differ e.g. that segment 707 has a low average speed. The user is then offered a choice between the computed routes, such as by requiring a user input, which may be in the form of a button press on the display device 230 to accept one of the displayed routes.

In other embodiments, an estimated time required to travel each of the determined routes is determined by the multiple route calculation module 490. The multiple route calculation module 490 calculates an estimated time required to travel the first route T(1 ) and an estimated time required to travel the second route T(2). The multiple route calculation module 490 may also calculate the estimated time required to travel any further computed routes. The multiple route calculation module 490 then calculates a difference between the times required to travel the plurality of routes and, if a significant difference is determined between the routes, the user is offered a choice between those routes. In one embodiment, the multiple route calculation module 490 calculates whether the estimated times required by the routes differ by more than a predetermined percentage. If the routes differ by more than the predetermined percentage, then the user is provided with an indication on the display device 230 of those routes and of the estimated times required to travel those routes. The user is then offered a choice between the computed routes differing by more than the predetermined percentage. Once selected, the user is provided with guidance along the selected route to the destination.

Advantageously, embodiments of the present invention provide the user with information concerning each of a plurality of available routes determined with respect to map data and varying amounts or types of additional information.

It will be apparent from the foregoing that the teachings of the present invention provide an arrangement whereby a user is provided with a more realistic view of a destination location and, optionally, facilities such as car parking in the vicinity of that location, which view allows the user to more easily navigate to that destination.

It will also be appreciated that whilst various aspects and embodiments of the present invention have heretofore been described, the scope of the present invention is not limited to the particular arrangements set out herein and instead extends to encompass all arrangements, and modifications and alterations thereto, which fall within the scope of the appended claims.

For example, whilst embodiments described in the foregoing detailed description refer to GPS, it should be noted that the navigation device may utilise any kind of position sensing technology as an alternative to (or indeed in addition to) GPS. For example the navigation device may utilise using other global navigation satellite systems such as the European Galileo system. Equally, it is not limited to satellite based but could readily function using ground based beacons or any other kind of system that enables the device to determine its geographic location.

It will also be well understood by persons of ordinary skill in the art that whilst the preferred embodiment implements certain functionality by means of software, that functionality could equally be implemented solely in hardware (for example by means of one or more ASICs (application specific integrated circuit)) or indeed by a mix of hardware and software. As such, the scope of the present invention should not be interpreted as being limited only to being implemented in software.

Lastly, it should also be noted that whilst the accompanying claims set out particular combinations of features described herein, the scope of the present invention is not limited to the particular combinations hereafter claimed, but instead extends to encompass any combination of features or embodiments herein disclosed irrespective of whether or not that particular combination has been specifically enumerated in the accompanying claims at this time.

Claims

1 . A navigation device (200) comprising: a processor (210); a store (230) for map data; and means (322) to access one or more types of additional information for use in route computation; characterised in that the navigation device (200) further comprises: a multiple route computation module (490) arranged to determine a first route from a start location to a destination location using the map data and one or more types of additional information and to determine one or more additional routes using the map data and fewer, or different, types of additional information from the first route.

2 The navigation device (200) of claim 1 , wherein the multiple route computation module (490) is arranged to compare each of the determined routes and to discard those routes which are identical to the first route.

3. The navigation device (200) of claim 1 or 2, comprising a display device (240) wherein the multiple route computation module (490) is arranged to display on the display device (240) information indicative of each of the determined routes.

4. The navigation device (200) of claim 1 , 2 or 3, wherein the multiple route computation module (490) is arranged to request a user input selecting one of the determined routes.

5 The navigation device (200) of claim 3 or 4, wherein the multiple route computation module (490) is arranged to calculate an estimated travelling time for each of the determined routes and to only display an indication of a determined route when a difference between the estimated time for that route and the first route exceeds a predetermined threshold.

6 The navigation device (200) of claim 5, wherein the multiple route computation module (490) is arranged to determine when the estimated travelling time for each of the determined routes differs by more than a predetermined percentage.

7. The navigation device (200) of any preceding claim, wherein the types of additional information comprise one or more of traffic information, road condition information and/or toll information.

8. The navigation device (200) of any preceding claim, wherein the multiple route computation module (490) is arranged to determine the second route using the map data and no additional information.

9. A method of route calculation for use in a navigation apparatus (200), the method comprising the steps of: determining a first route from a start location to a destination location using map data and at least one type of additional information; characterised by: determining a second route from the start location to the destination location using the map data and either fewer or different types of additional information than the first route.

10. The method of claim 9, comprising comparing each of the determined routes and discarding those routes which are identical to the first route.

1 1 . The method of claim 9 or 10, comprising displaying information indicative of the first and second routes to a user.

12. The method of claim 1 1 , comprising calculating an estimated travelling time for each of the determined routes and only displaying information indicative of those routes whose estimated travelling times differ by more than a predetermined amount.

13. The method of claim 1 1 or 12, comprising receiving a user input selecting one of the displayed routes to provide route guidance for the selected route.

14. The method of claim 9, wherein the second route is determined using the map data but without any additional information.

15. Computer software comprising one or more software modules operable, when executed in an execution environment, to cause a processor (210) to perform the method of claims 9 to 14.