WO2015015255A1

WO2015015255A1 - Method and system for navigation with presentation of the route by alternation of modes

Info

Publication number: WO2015015255A1
Application number: PCT/IB2014/000045
Authority: WO
Inventors: Pierre Hayot
Original assignee: Michelin Travel Partner
Priority date: 2013-08-02
Filing date: 2014-01-17
Publication date: 2015-02-05

Abstract

Method of navigation for road navigation apparatus comprising a viewing screen (44) enabling a driver to receive a succession of visual alerts intended for ensuring the following of a precalculated road route, comprising the following steps: - a plurality of resting steps (100, 200), during which the overall level of the luminous intensity emitted by the viewing screen (44) is less than a so-called resting threshold, and during which an alert module (14) verifies whether the distance between the vehicle travelling along the route and the point of triggering of the next alert phase is less than or equal to an alert threshold; - a plurality of alert steps (104, 204) comprising an instantaneous increasing of the overall level of the luminous intensity emitted by the viewing screen by at least 50%, and preferably by more than 75% with respect to the resting step, in conjunction with the displaying of a guidance instruction; - the resting and alert steps alternating successively with one another.

Description

METHOD AND SYSTEM FOR NAVIGATION WITH ROUTE PRESENTATION BY ALTERNATING MODES

TECHNICAL FIELD OF THE INVENTION [0001] The present invention relates to a navigation system comprising access to road mapping data, at least one microprocessor, at least one working memory, a route calculation module. The invention also provides a corresponding navigation method. STATE OF THE PRIOR ART

Methods and navigation systems operating with mobile devices are well known and have even become common tools for a considerable number of road users. For several years, commercialized navigation devices have relatively small screens, but have a number of data increasingly important. Users are fond of devices with presentations simulating a driver's point of view on the road. The effects of realism and image quality also reach particularly high levels.

In return, the amounts of data to be stored, processed and displayed have increased dramatically. Yet, despite all these improvements, the accuracy of the routes presented or the ease of reading has not progressed. In fact, the generalization of display modes with a background map scrolling with very realistic color images has actually helped to make the use more enjoyable or attractive, without facilitating the reading or understanding of the data displayed. The aesthetic and attractive side of the current devices also creates a distracting effect for the driver. On the other hand, most of the current devices are autonomous and non-communicating, and therefore include all the map data useful for calculating routes and displaying maps on which the routes are shown. Given the large amount of data to be processed and stored, these devices require significant capacity both in terms of memory and the microprocessor used. In addition to their complexity and high cost, this type of device has the disadvantage of containing data that quickly become outdated if no update is made. Finally, an autonomous device can not in any case provide data whose life is very short, such as traffic-related data.

To avoid these disadvantages, some suppliers have developed centralized systems, in which a central server provides routing calculations for a large community of users. The data, further comprising road maps, are then transmitted from the server to the mobile device. Such an implementation involves the exchange of large volumes of data, little compatible with a very limited bandwidth for each receiver, especially in certain places or moments. Furthermore, the display of the route in the form of a road map with a large amount of information has the disadvantage of soliciting the user too intensely, often for obtaining information irrelevant in look at the route to follow.

Document US 2004/117108 describes a navigation system in which the route to be followed is divided into segments sequentially transmitted to a mobile navigation terminal from the segments calculated at a route server. The transmissions are made at given points of the calculated route. Subsequent segments are transmitted when a given point of a previous segment is reached. The described system involves the transmission of segment data in addition to the specific point data. This segment data greatly increases the amount of data that must be transmitted from the server to the mobile devices. Document US 2009/112462 describes a navigation system in which the route guidance list is hierarchized so that the information concerning the maneuvering actions at locations closer to the user's position take precedence. For example, in the route guidance list, information about the immediate maneuvering location is more detailed, enlarged, and highlighted relative to others. To transmit the information to the user, the method uses a list of maneuvers.

US 2003/078729 discloses a navigation system in which the road guidance information is adapted for use on a small screen. Road guidance information display elements are mapped to numeric keys in ascending numerical order by means of hyperlinks. Each file is divided so that each item does not fall below the expected size of the file. The presented system implies an alternation of continuities displayed sometimes before, sometimes after an instruction. This non-constancy of the display mode compels the user to adapt each time the mode changes, causing great confusion and affecting speed of interpretation of the data.

US 5544060 discloses a navigation system for a vehicle allowing a user to obtain an optimal route between a starting point and a destination, before departure. Once the optimum path has been calculated, a preview function allows the user to visualize the calculated path either before departure or at any point along the optimal path. The approach presented in this document involves only the distance to the next maneuver, with no notion of continuity. Thus, in general, the existing methods and navigation systems are not very ergonomic and are generally greedy in memory capacity, storage capacity and data processing capacity. Also known navigation devices provided with brightness sensors to automatically adjust the intensity of the display of the screen. This type of arrangement also makes it possible to reduce the luminous intensity of the screen at night or when passing through tunnels so as not to dazzle the driver. The variation in light intensity is directly related to the results of the measurements of the light sensor and remains independent of the route and the maneuvers to be performed.

To overcome these disadvantages, the invention provides different technical means.

SUMMARY OF THE INVENTION

A first object of the invention to provide a system and a navigation method with optimized ergonomics, facilitating understanding and use, safely.

Another object of the invention is to provide a system and a navigation method for facilitating the reading and understanding of the route data.

Another object of the invention is to provide a system and a navigation method for reducing the distraction sources of the driver of a vehicle equipped with such a device.

Another object of the invention to provide a system and a method of navigation to prevent maneuvers or driving actions are not recognized timely or not performed by the driver but also that maneuvers are incorrectly interpreted or misunderstood. Another object of the invention is to provide a system and a simplified navigation method, thereby reducing the sources of distractions that may affect the concentration of the driver. Yet another object of the invention to provide a system and a navigation method to reduce the driver's cognitive load, allowing him to focus on the basic functions, namely driving the vehicle safely . Yet another object of the invention is to provide a system and a method of navigation to attract attention in a targeted manner or synchronized with the precise moment when the driver must perform a driving act. Yet another object of the invention to provide a system and a navigation method thus improving the general safety of the driver and his passengers when following a route.

Yet another object of the invention is to provide a system and a navigation method to avoid distracting the driver immediately before a driving action.

Yet another object of the invention is to provide a system and a method of navigation for soliciting a reflex of the driver to reduce the effort and / or the reaction time.

Finally another object of the invention is to provide a system and a navigation method allowing the driver to maintain maximum availability and attention to maintain a reaction time as low as possible in case of solicitation for urgent action (accident, sudden avoidance of a person or object, etc.). Indications or voice instructions may require a relatively long time to express the statement as a whole, which may cause errors in route tracking. In addition, a statement is often less precise than a diagram and in particular to follow a route, a precise and clear diagram is more effective than a long explanatory speech.

To do this, the invention provides a navigation method for a navigation device comprising a display screen, allowing a driver to receive a succession of visual alerts for monitoring a route route pre- calculated, comprising the following steps:

a plurality of rest stages, during which the overall level of the light intensity emitted by the display screen is less than a so-called rest threshold, and during which an alert module checks whether the distance between the vehicle while traveling along the route and the initiation point of the next warning phase is less than or equal to an alert threshold;

a plurality of alerting steps (or visual signal stimulus intended for the user) comprising an instantaneous increase in the overall level of the light intensity emitted by the viewing screen (and perceived by the user) of at least 50%, and preferably more than 75% relative to the resting step, (or even 80, 90 or 100%), in connection with the display of a guidance instruction (maneuver).

- the stages of rest and alert successively alternating with each other. The instantaneous variation of the luminous intensity between a rest phase and an alert phase has the effect of stimulating the user's visual system in order to alert the user to perform a series of body gestures allowing the realization of the maneuver. The data of the maneuver is provided to the user so that he can perform the actions in relation to the latter.

A possible brief sound signal can support the visual stimulus. Depending on the cognitive preference, it may be suitable for some drivers. The one-off transmission of succinct data to implement the driving actions is considered an alert mode, with a content and a display format to alert the driver to ensure that the key data are well understood and understood by the driver. This also makes it possible to solicit the concentration of the driver only intermittently and during short periods of time, since a driver can not remain concentrated for a long time on a captivating or absorbing activity or requiring a high concentration such as reading or interpreting a card, in particular when its central position, orientation, or scale vary.

Advantageously, in display mode for rest phase, the display is devoid of visually attractive elements (except punctually and for reasons unrelated to the guidance: area of vigilance, danger, tourist site, etc.). .

In an advantageous embodiment, the display mode for rest phase corresponds to a substantially black or dark window. Such a type of display symbolizes for example a lack of driving action to undertake or predict.

According to an alternative embodiment, the transition from a rest phase to an alert phase (or visual signal stimulus) is generated by detecting a distance until the next driving action less than one. action alert threshold.

According to another embodiment, the passage test is based on an estimate of the time required to reach the next driving action. According to another embodiment, the display of an alert phase ends upon reaching the vehicle engaged in the corresponding maneuver of a position corresponding to a "driving action threshold performed". . The invention also provides a navigation system provided with a mobile navigation device having access to road mapping data in relation to at least one geographical area and for determining a plurality of routes in this area. at least one microprocessor, at least one working memory, a route calculation module, a display screen and furthermore comprising:

a geolocation and matching module, making it possible, when moving the mobile navigation device, to determine the real position of the latter; a navigation module for transmitting the navigation elements to the user;

an alert module for verifying whether the distance between the vehicle being moved along the route and the starting point of the next warning step is less than or equal to an alert threshold;

a luminance module for determining and managing the variation of the level of the luminous intensity of the display screen between the rest and alert phases, as a function of the output data of the alert module.

According to an advantageous embodiment, the navigation system comprises a centralized server having access to road mapping data in relation to at least one geographical area and making it possible to determine a plurality of routes in this area, a plurality of mobile navigation module, capable of being in communication at least temporarily with the central server for exchanging data, wherein the digital road map data is stored at the server.

In an advantageous variant, the route calculation module, the alert module and the luminance module, are provided at the server.

According to another embodiment, the route calculation module is provided at the server, while the alert module and the module of luminance are provided at the level of the autonomous device. In such an alternative, the basic rules for the implementation of the guidance are established at the server level, and the implementation of the particular tests is delegated to the level of the autonomous device.

According to yet another variant, the mobile navigation device comprises all the modules and operates autonomously.

The invention finally provides a computer program product intended to be loaded into a memory associated with a processor, the computer program product comprising portions of software code implementing the previously described method when the program is executed by the processor.

DESCRIPTION OF THE FIGURES

All the details of embodiment are given in the description which follows, supplemented by FIGS. 1 to 10, presented solely for purposes of non-limiting examples, and in which:

FIG. 1A is a schematic representation of a method of alternating mode navigation according to the invention;

FIG. 1B is a schematic representation of an autonomous mobile navigation method according to the invention;

- Figure 1C illustrates the scale of clarity for a neutral color according to the International Commission on Lighting;

FIG. 2 is a functional flowchart illustrating the main steps of an alternating mode navigation method according to the invention;

FIG. 3 is a functional flow diagram complementary to that of FIG. 2, showing additional steps of a preferred embodiment of the invention;

FIGS. 4 to 9 show examples of navigation windows according to the invention; FIG. 10 represents a hierarchy table of the information. DETAILED DESCRIPTION OF THE INVENTION DEFINITIONS

By "global level of brightness" means the level of perceived brightness of the user likely to produce a signal stimulus in this user when it is increased beyond a threshold of stimulus. It can be a substantially uniform brightness level across the screen that increases uniformly, or a restricted area of the screen whose brightness level increases significantly, to generate the stimulus.

By "threshold of rest" is meant a value of the light intensity less than 50% (and more preferably less than or equal to 30%) on the scale of clarity of Figure 1C.

By alerting step or "visual signal stimulus" is meant a step during which a stimulus effect generated by an instantaneous increase in the overall level of light intensity by the screen of a device of the invention. navigation in which, contrary to conventional displays where the displayed data is intended for cognitive purposes for the user, the signal stimulus is a pulse or stimulation by an external element to the user, in this case the screen of the navigation device , which stimulates the visual system of the user, causing the latter an instant reaction, regardless of any cognitive data to be transmitted to the user.

For the sequence of body gestures is in relation to the step of the route in progress, data are simultaneously or within a few seconds (eg between 1 to 5 seconds) displayed on the screen preferably in the form of a schematic representation or symbols or pictograms indicating or evoking the actions to be performed. For example, a arrow to the left or right indicates to the user that he must perform the actions of turning the steering wheel in the corresponding direction.

The International Commission on Illumination (CIE) proposes a definition of the brightness L ^* , (often referred to as clarity), from the luminance of the color (expressed in candelas per square meter (cd.m-2). )), relative to the luminance of the white, used as a reference. The brightness in this case is a value between 0 and 100, as shown in the scale of clarity shown in Figure 1C. A gray having a reflection factor of 18% (from the photometric point of view as from the energy or radiometric point of view) will have a brightness of about 50%.

By "idle phase display mode" is meant a display mode in which the user screen displays a black or very dark screen without data corresponding to guidance indications. As a variant, the user screen displays, using dark colorations and / or low light intensities, secondary data, not related to an immediate driving action. The term "rest phase" means a driving phase during which a driver continues to progress according to the previously engaged driving action. During the rest period, no alert, no map, no indication of continuity is displayed. The term "action phase", or "driving action", a driving phase during which a driver performs a driving maneuver at the wheel of his vehicle without which the follow-up of the planned route would not be possible. assured. The term "indication of continuity" means a pictogram, sign or symbol indicating the driver of the vehicle pursuing a route to continue to follow a direction or route previously selected. The term "action action threshold performed" means a marker for indicating the time and / or the position at which it can be considered that a vehicle has crossed or carried out irreversibly (ie without performing any counter-maneuver) a given driving action.

After several years during which the technologies related to guiding and tracking routes have been oriented on very rich content and dense cartographic and visual elements of all kinds, the inventors have found that the current solutions are not optimal because the driver is "drowned" in a mass of data that he must read, understand, analyze, and interpret, while at the same time ensuring safe driving of the vehicle.

Solutions with high visual or multimedia content generate a significant error tracking rate and a loss of efficiency of the driver. For example, on a roundabout, the map moves too much and the position of the vehicle is imprecise, causing regular tracking errors.

In another example, cognitive overload (in addition, due to the presence of a large number of data of varied nature such as distance, pictograms, map data, direction data, data in relationship with expected arrival, current track data, etc.), leads to numerous route tracking errors. Cognitive overload can also cause fatigue and / or stress for the driver.

The inventors have therefore researched and identified the conditions required to allow better transmission of guidance data to the driver, reduce the time of interpretation of these data, and release the driver so that it remains available to ensure safe driving of the vehicle.

i) the driver must be available;

(ii) the driver must be notified; (option) (iii) the driver must be able to maintain maximum physical and mental availability when conducting a driving action;

(iv) the efficiency ratio of the transmission of driver guidance data increases if, at the moment of transmitting the data, the driver's attention is strongly stimulated or solicited, but for a short time.

To enable these conditions to be met, the device and method according to the invention propose to suppress the systematic display of data in the form of road maps or geographical maps. This display is then reserved for special situations at the request of the driver, or better of a passenger co-pilot. One of these situations is the consultation of the traffic map at a stop at a traffic light.

Finally, the stimulation period must be of substantially short duration, be initiated just before the act of driving to be performed and end when the driving action ends and / or becomes irreversible. It should be noted that an action / alert display can follow an action / alert display when two or more pipe maneuvers succeed one another. Example: Rest Alert Rest Rest Alert Alert Alert Alert Rest Alert When two or more maneuvers follow one another very closely, they are displayed in one action display.

FIG. 1A shows an example of an embodiment of a navigation system 1 according to the invention: On the one hand there is a route server 10, designed to generate all the data relating to the route for which a route is to be produced and the navigation performed. The route server 10 comprises at least one microprocessor 11, for the execution of processor instructions or commands specifically provided for, a data exchange module 12, capable of receiving and transmitting data with a processor. plurality of mobile navigation devices 40. In addition, the data exchange module 12 makes it possible to receive requests for itineraries of mobile navigation devices 40 with start and end point data, and to transmit to a mobile navigation device 40 (either the requesting device or one or more others) the data established by the server 10. A means of communication, transfer or exchange of data or order, for example a bus 24 is provided to ensure the exchanges required between the microprocessor 11 and the different modules.

The route server 10 comprises a route calculation module 13 operating in a manner known in itself, using an algorithm for determining the shortest path between two points, such as Dijkstra or other. Such an algorithm makes it possible, with the aid of a microprocessor and the required processor instructions, to carry out the exploration of a very large number of possibilities (of a few tens or hundreds for low density areas and / or for short routes to a few hundred thousand or more, for areas with high road density and / or for long routes) in order to elect an optimal route according to given criteria, such as the most short, or the fastest, etc.

Once the route is known, a module for detecting points of maneuvers or instruction points 16 makes it possible to detect the points of maneuvering along the route, that is to say the points or zones. where maneuvers must be made to follow the planned route. Maneuvering mainly means a driving action of a vehicle for selecting or not a given section when the driver is faced with an opportunity to engage his vehicle to a plurality of sections (at least two). The driver is faced with many opportunities to continue his journey, and a maneuver allows him to engage his vehicle according to the direction provided by the pre-established route. Thus, the module 16 performs a virtual route of the route established by the module 13, and identifies the points or nodes where multiple sections are attached. It can be intersection of roads, exits or entry on highways, and forks, etc. The maneuvering points are determined in a manner known in itself. For a roundabout, it is understood that a plurality of simple maneuvers are generally involved, from the entrance to the roundabout, then to the passage of each exit, each time involving a maneuver consisting of either staying on the roundabout or out, until the actual exit of the roundabout. In this document, the roundabouts are considered a single action, such as "take the ^3rd exit", consisting in fact a complex maneuver, as mentioned above, or type "turn left", in considering the entire roundabout as a single crossroads of several roads.

The route server 10 also includes an alert module 14 to check if the distance between the vehicle being moved along the route and the starting point of the next warning step is less than or equal to an alert threshold. If so, the alert module 14 transmits to the luminance module a signal or data indicating to switch to the alert mode. In addition, the alert module generates the display of the navigation data to be displayed in correspondence with the position of the alert zone concerned.

Otherwise, the alert module 14 transmits to the luminance module a signal or data indicating to keep the mode "rest".

In "alert" mode, the alert module 14 also determines the distance between the vehicle being moved along the route and the starting point of the next warning step to determine if this distance is below the alert threshold. If so, the alert module 14 transmits to the luminance module 15 a signal or data indicating to keep the "alert" mode. However, the display is updated to display the navigation data according to the new maneuver to be performed. If not, the alert module 14 transmits to the luminance module a signal or data indicating to switch to the idle mode.

The route server 10 also comprises a luminance module 15 for determining and managing the variation in the level of the light intensity of the display screen 44 between the rest and alert phases, in function of the data obtained by the alert module 14.

The route server 10 furthermore includes a direction data availability test module 17. This direction data test module 17 is designed to check in the road map databases 19 the maneuvering points for which direction data to follow are available in the database. This data means, for example, that one or more traffic signs displaying a relevant direction are present along the road concerned. This test is preferably carried out before the generation of the route, in order to allow a specific treatment according to the result of the test. Thus, if direction data is available, it is used to constitute the navigation windows. If no direction data is available for one or more points of maneuver, the method provides, for these points of maneuvering, a step of geometric reconstruction of the useful sections illustrating the maneuvers to continue the route.

To perform the test, the direction data test module 17 reviews all the points of maneuver detected for a given route to determine whether the road map data includes or not direction data to follow. In practice, these data are often present for major highways such as motorways or national roads.

The data used by the route server 10 come from a module or database of road map data 19 provided in the route server 10 as shown in the example shown, or at a location external to the server to which it can access if necessary. Similarly, the routes established by the server can be stored in an established module or route database 21, provided within the server 10 as shown in the illustrated example, or at a location external to the server to which it is it can access as needed. The same is true for the direction data, the navigation phase data and the phase change data, which can be stored respectively in modules or databases of directions 20, navigation phases 22 and change of direction. phases 23, provided within the server 10 as shown in the example shown, or at a location external to the server to which it can access if necessary.

A route server 10 is designed to be in communication, for example via a cellular or other telecommunication network, as needed, with a plurality of mobile navigation devices 40. Each of the devices mobile navigation system 40 has a data exchange module 42, designed to transmit route requests to a route server 10, and to receive in return the data set by the server 10. The navigation devices 40 comprise, in addition to a microprocessor 41 and at least one working memory 48, a navigation module 43, for providing and managing the transmission to the user of the navigation windows received from a route server 10. This transmission is preferably provided by display on a display screen 44. A means for communicating, transferring or exchanging data or order, for example a bus 51 is provided to ensure the exchanges required between the microprocessor 41 and the different modules.

The mobile navigation device 40 further comprises a geolocation and matching module 45 adapted on the one hand to receive the position data of the mobile navigation device 40 and on the other hand to ensure a correspondence between the raw position data received from the geolocation device and the positions assigned to the maneuvering points and alerts.

Figure 1B shows an alternative embodiment in which the mobile navigation devices operate autonomously. Such a device thus comprises all the modules previously described in relation with the server 10 (namely the microprocessor modules 11, route calculation 13, alert 14, luminance 15, detection maneuver 16, availability test direction data 17, RAM 18, route map 19, direction data 20, route data 21, navigation phase data 22 and phase change data 23) except for the data exchange module. data 12. It furthermore comprises the following modules, previously described in relation to the mobile navigation device 1, namely a navigation module 43, a display module or screen 44, a geolocation and matching module 45. All of these modules work locally without having to transfer data between a server and a mobile browser. Such a device has the advantage of being autonomous, independent of the availability of communication networks. The route data displayed in the form of fixed windows allows this device to offer users excellent readability, optimal ergonomics, and a removal of animation sources, such as the scrolling of a cartographic background, which are important source of driver attention loss. The implementation of the various modules of the server 10 and the mobile navigation devices 40 previously described is advantageously performed by means of processor instructions or commands, allowing the modules to perform the operation or operations specifically provided for the module. concerned. The processor instructions may be in the form of one or more software or software modules implemented by one or more microprocessors. The module or modules and / or the software or the software are advantageously provided in a computer program product comprising a recording medium or recording medium usable by a computer and having programmed code readable by a computer integrated in said medium or medium, allowing application software to run on a computer or other device comprising a microprocessor such as a device navigation.

According to various alternative embodiments, the microprocessors 11 and 41, as well as the working memories 18 and 48 can be centralized for all the modules of the route server 10 or the mobile navigation device 40, or else be arranged externally, with connection to the different modules, or be distributed locally so that one or more modules each have a microprocessor and / or a working memory.

[0076] Figure 2 shows, in succession, the main steps of the method according to the invention. In step 100, the system is (by default) in idle mode or phase. During this phase, the warning module 14 compares (step 101) the current distance separating the vehicle carrying out the current route from the next alert point to an alert threshold value. If the distance is less than the alert threshold (step 102), the alert module generates a mode change to enter the "alert" mode (step 104). Otherwise, the "rest" mode is maintained (return to step 100).

In alert mode, the alert module 14 compares the current distance separating the vehicle from the next alert point to the alert threshold value. If the distance is greater than the alert threshold, the alert module generates a mode change to enter the "rest" mode. Otherwise, the "alert" mode is maintained. The screen then displays the navigation data corresponding to the new action to be performed.

Alternatively, each alert phase is followed by a rest phase, even if it is of very short duration. In current practice, the method allows for a succession of steps alternating rest phases and alerts. During the rest phases, the overall level of the light intensity emitted by the display screen is below a rest threshold. An example of a threshold of rest is presented in relation to FIG. 1C. According to this example, the quiescent threshold corresponds to a value of the luminous intensity of less than 50% (and more preferably less than or equal to 30%) on the scale of clarity of FIG. 1C.

During the alert phases, the luminance module manages the light intensity so as to increase substantially instantaneously the overall level of the light intensity emitted by the viewing screen (and perceived by the user) of at least 50%, and preferably more than 75% relative to the resting stage, (even 80, 90 or 100%). Figure 1C illustrates a representative example of the change in brightness as a function of the percentage of clarity. Alert phases are also used to display the relevant guidance data on the screen depending on the position of the vehicle. The sudden increase in the level of brightness creates a visual signal stimulus effect intended for the user and soliciting the reflexes of the latter, allowing him to react instantly. At this level of reaction, the user does not need to concentrate or use his or her intellectual faculties to read or interpret the information on the screen, contrary to conventional uses of visual guidance systems.

Figure 3 shows an alternative embodiment of the method. According to this variant, an additional threshold, designated vigilance threshold (or pre-alert), is provided before reaching the alert threshold. Achieving this threshold will draw the driver's attention to the imminent arrival of an alert phase. This threshold is particularly advantageous for example following a prolonged rest period, in order to prepare the driver to receive instructions.

In step 200, the idle mode is applied, preferably by default. In step 201, the alert module compares the current distance separating the vehicle taking the current route of the next vigilance point to a vigilance threshold value. If the distance is below the vigilance threshold (step 202), the alert module generates a mode change to switch to the "vigilance" mode. Otherwise, the "rest" mode is maintained (return to step 200).

When the vigilance threshold is crossed, the alert module 14 compares (step 203) the current distance separating the vehicle carrying out the current route from the next alert point to an alert threshold value. If the distance is below the alert threshold, the alert module generates a mode change to enter the "alert" mode (step 204). Otherwise, the "vigilance" mode is maintained (return to step 202). Finally, after an alert phase, the alert module performs the necessary comparisons between the distances in progress and the various potential thresholds and, depending on the case detected, generates the data required to switch to the mode concerned (rest, alertness or alert).

Figures 4 to 9 illustrate display examples obtained by means of the device and the method according to the invention. In particular, the significant level of contrast between the rest phase and the warning phase of the example of FIG. 4 and the examples of the following figures is observed. During a route tracking, these displays are presented alternately, dynamically, making the contrast even more striking. Displaying the alert in substantially full screen mode, with a high light intensity, also contributes to the effectiveness of the alert. The transitions between the display screens are observed in which the previously described levels of variations in the light intensity of the display screen are applied according to the types of transitions.

As illustrated in these examples, contextual data can also be displayed. This may include, for example, data concerning:

- safety: radars, danger zones, speeding, atypical speeds, dangerous turns, dangerous slopes; - services: accommodation, meals, fuel stations, rest area, playground, etc. ;

- traffic and / or weather data;

- "reinsurance" data: passage nearby, works of art, etc.

- tourism or entertainment data: object to report on the passage or to propose for a visit, activities, events.

When several changes of direction follow one another at substantially short intervals, they are advantageously aggregated into a single navigation window having a single pattern. The aggregation threshold is for example 3 seconds.

As shown in the examples, the display module may also include data in relation to the intended arrival at destination. For example, arrival data may include items such as mileage to travel before arrival, time remaining before arrival, estimated time of arrival, etc. Other information, such as a possible delay or additional delay related to significant traffic on the route can also be displayed. The displayable elements may optionally be user-definable.

Various variants:

In all these examples, the windows are fixed type, or without displacement, that is to say that the displayed content does not move on the screen depending on the progression of the mobile device along the screen. 'route.

The figures and their descriptions made above illustrate the invention rather than limiting it. In particular, the invention and its various variants have just been described in connection with a particular example in which the mobile device is integrated with a mobile phone type "Smartphone". Nevertheless, it is obvious to a person skilled in the art that the invention can be extended to other embodiments in which, in variants, the mobile device is integrated with a road vehicle, as part of a vehicle. dashboard equipment.

The reference signs in the claims are not limiting in nature. The verbs "understand" and "include" do not exclude the presence of elements other than those listed in the claims.

Claims

2015/015255 - 24 - CLAIMS

A navigation method for a road navigation apparatus comprising a display screen (44), enabling a driver to receive a succession of visual alerts for following a pre-calculated road route, comprising the steps of:

a plurality of rest stages (100, 200), during which the overall level of the light intensity emitted by the display screen (44) is less than a so-called rest threshold, and during which a module of alert (14) checks whether the distance between the vehicle being moved along the route and the initiation point of the next warning phase is less than or equal to an alert threshold;

a plurality of alerting steps (104, 204) comprising an instantaneous increase in the overall level of the light intensity emitted by the display screen by at least 50%, and preferably by more than 75% relative to in the resting step, in connection with the display of a guidance instruction;

- the stages of rest and alert successively alternating with each other.

2. Navigation method according to claim 1, wherein the display mode for idle phase corresponds to a substantially black or dark window.

3. Navigation method according to one of claims 1 or 2, wherein the transition from a rest phase to an alert phase is generated by a detection of a distance until the next action d conduitë less than an action alert threshold.

4. Navigation method according to one of claims 1 to 3, wherein the display of an alert phase ends upon reaching the vehicle engaged in the corresponding maneuver a position corresponding to a "threshold conduct action carried out ". 2015/015255

- 25 -

A navigation system (1) provided with a mobile navigation device having access to road map data (19) in relation to at least one geographical area and for determining a plurality of routes in that area, at least one microprocessor (11; 41), at least one working memory (18; 48), a route calculation module (13), a display screen (44) and further comprising:

a geolocation and matching module (45), making it possible, during the displacement of the mobile navigation device, to determine the real position of the latter;

a navigation module (43) for transmitting the navigation elements to the user;

an alert module (14) for checking whether the distance between the vehicle traveling along the route and the starting point of the next warning step is less than or equal to a threshold of alert;

a luminance module (15) making it possible to determine and manage the variation of the level of the luminous intensity of the display screen (44) between the rest and alert phases, according to the output data the alert module (14).

6. Navigation system (1) according to claim 5, comprising a centralized server (10) having access to road mapping data (19) in relation to at least one geographical area and for determining a plurality of routes in this area, a plurality of mobile navigation modules (40), capable of being in communication at least temporarily with the central server (10) for exchanging data, in which the digital road map data is stored at the server level .

7. Navigation system according to one of claims 5 or 6, wherein the route calculation module (13), the alert module (14) and the luminance module (15) are provided at the level of server. 2015/015255

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8. Navigation system according to one of claims 5 or 6, wherein the route calculation module (13) is provided at the server, while the alert module (14) and the luminance module ( 15) are provided at the level of the autonomous device.

9. Navigation system (1) according to one of claims 5 or 6, wherein the mobile navigation device comprises all the modules and operates autonomously.

10. A computer program product intended to be loaded into a memory associated with a processor, the computer program product comprising portions of software code implementing the method according to one of claims 1 to 4 when the program is executed by the processor.