This specification describes a method and a device pertaining to a vehicle. More specifically it indicates a method and a device for calculating and adapting the speed of a vehicle for a desired arrival time at a destination.

BACKGROUND

Driving a vehicle involves constantly achieving a balance between driving fast/increasing speed (and thereby reaching the destination in good time) and driving more slowly/reducing speed (and thereby saving fuel but having a smaller margin on delivery time).

Vehicle in this context means for example truck, long-haul carrier, platform truck, transport vehicle, wheel-mounted loader, bus, motorcycle, off-road vehicle, tracked vehicle, snow scooter, armoured vehicle, four-wheeler, tractor, car or other similar powered means of transport, manned or unmanned, suited to land-based geographical movement.

The choice of speed is complicated for various reasons. Engine performance, cargo weight, estimated future traffic situations and road characteristics such as topology may make it difficult to judge the appropriate speed at each time along the route. Another factor is variations in the traffic situation on parts of the itinerary, e.g. queuing, roadworks, closed traffic lanes etc. The possibility of travelling in vehicle trains, so-called "platooning", along the whole or parts of the route to the destination may also affect the optimum speed, since it is fuel-economisingly advantageous to travel in such vehicle trains, because of less air resistance.

It is also difficult to judge how to take account of the cost of possible delays when choosing the speed to adopt along a route. The cost of such delays may in fact range all the way from being entirely negligible economically to being very expensive because of delay penalties or other commercial losses such as damage to relations with customers. It may therefore be difficult for the vehicle's driver to work out the optimum speed from an overall perspective. A higher speed to "be on the safe side" as regards delivery time will lead to higher fuel consumption, more harm to the environment, greater vehicle wear, shorter service intervals, more accident risks and worse consequences of accidents, to mention only some disadvantages. Arriving at the destination too early may also often mean the driver having to sit and wait before being able to load/unload, i.e. the time gained will rarely make it possible to undertake an extra driving assignment, so no real advantage accrues. WO20171498 refers to a cruise control for which a destination and a desired arrival time are chosen. The cruise control then calculates the most optimum speed with regard to fuel consumption.

A problem with that solution is constantly endeavouring to conform to appointed times without regard to possible unforeseen obstacles along the respective route. It also fails to take account of the value of arriving on time and to balance it against for example the increased fuel cost which this may entail if the speed has to be increased.

US201 30041621 describes a way of arriving at the optimum speed with respect to fuel consumption while also taking other cost factors into account so that maximum profitability is achieved. This solution takes no account at all of delivery time and the cost of not achieving it. Nor does it cater for unforeseen events en route and the probability that they may occur and affect journey time to various extents.

This solution also assumes that the vehicle achieves constant revenue per kilometre travelled and that driving faster will therefore result in greater revenue. This assumption is well out of line with reality in many vehicles, except possibly taxis or the like. Often it is not possible to undertake an extra journey simply because of arriving at the final destination a quarter of an hour sooner. Nor does this solution cater for other limitations pertaining to the vehicle, the traffic situation, the road and/or topographical conditions.

It may be appreciated that much has yet to be done to make it easier for a driver to plan his/her journey and be able to calculate an optimum speed for achieving delivery on time.

SUMMARY

It is therefore an object of this invention to be able to solve at least some of the problems indicated above and improve the method for calculating and adapting the speed of a vehicle for a desired arrival time at a destination.

I n a first aspect of the invention this object is achieved by a method for calculating and adapting the speed of a vehicle for a desired arrival time at a destination. The method comprises registering the vehicle's destination and registering a desired arrival time at the destination registered. The method further comprises indicating a degree of importance of reaching the destination by the desired arrival time, and comprises detecting the vehicle's geographical location. The method comprises also detecting a current time and determining an itinerary from the vehicle's detected geographical location to the destination. In addition , the method comprises also calculating a distance between the vehicle's location and the destination along the itinerary determined. The method comprises also acquiring statistical information about average journey times for sections of the itinerary to the destination , and a density function which describes the spread of deviations from this average journey time. The method comprises also calculating a vehicle speed for reaching the destination by desired arrival time with as low fuel consumption as possible, this speed calculation being based on the calculated distance, the difference in time between desired arrival time and detected current time, the indicated degree of importance of reaching the destination by the desired arrival time, and the acquired statistical information and the density function. In addition, the method comprises also making it possible for the vehicle to be driven automatically at the speed calculated.

I n a second aspect of the invention this object is achieved by a device adapted to calculating and adapting the speed of a vehicle for a desired arrival time at a destination. The device comprises a processor circuit adapted to registering the vehicle's destination and to registering a desired arrival time at the destination registered. The processor circuit is also adapted to indicating a degree of importance of reaching the destination by the desired arrival time. The device is further adapted also to detecting the vehicle's geographical location and current time. The device is also adapted to determining an itinerary from the vehicle's detected geographical location to the destination. In addition, the device is adapted to calculating a distance between the vehicle's location and the destination along the itinerary determined. The device is further adapted also to acquiring statistical information about average journey times for sections of the itinerary to the destination along the itinerary determined. In addition, the device is also adapted to acquiring a density function for a spread of deviations from this average journey time. The device is also adapted to calculating a vehicle speed for reaching the destination by desired arrival time with as low fuel consumption as possible, this speed calculation being based on the calculated distance, the difference in time between desired arrival time and detected current time, the indicated degree of importance of reaching the destination by the desired arrival time, and the acquired statistical information and the density function, whereby the processing circuit makes it possible for the vehicle to be driven at the speed calculated. By building up and storing statistics about average journey time for travelling a certain itinerary to a certain destination, and also calculating a density function which indicates a spread of this average journey time, it is possible to calculate the probability of reaching the destination in a certain journey time or by a certain desired arrival time. By also indicating the degree of importance which the driver attributes to reaching the destination by the desired arrival time and charting this with respect to the calculated probability, e.g. by having a high degree of importance of achieving the desired arrival time charted against a high probability of doing so, it is possible to achieve better vehicle speed planning. Transport costs and environmental discharges may thus be reduced for freight operations which are not particularly time-sensitive, while at the same time the risk of delays to time- sensitive operations may be reduced by adopting a higher speed for them. Other advantages and further novel features are indicated by the detailed description set out below.

LIST OF DRAWINGS

Embodiments of the invention will now be described in more detail with reference to the attached drawings which illustrate various embodiment examples.

Figure 1 illustrates a vehicle in motion, according to an embodiment.

Figure 2 illustrates statistics about journey time for a certain route.

Figure 3A illustrates an example of a vehicle in an infrastructure according to an embodiment of the invention.

Figure 3B illustrates an example of a screen image according to an embodiment.

Figure 4 illustrates a vehicle in motion, according to an embodiment.

Figure 5A illustrates an example of a screen image according to an embodiment.

Figure 5B illustrates an example of a screen image according to an embodiment.

Figure 6 illustrates a relationship between cost and journey time for a certain route. Figure 7 is a flowchart illustrating an embodiment of the invention.

Figure 8 is an illustration of a control unit according to an embodiment of the invention.

Figure 9 is an illustration of two different scenarios, according to an embodiment.

DETAILED DESCRIPTION

Embodiments of the invention comprise a method and a device which are feasible according to some of the examples described below. This invention may however be implemented in many different forms and is not to be regarded as being limited by the embodiments herein described, which are intended instead to illuminate and clarify various aspects.

Further aspects and features of the invention may be indicated by the detailed description set out below when read in conjunction with the attached drawings. The drawings are nevertheless only to be regarded as examples of various embodiments of the invention and not as limiting the invention, which is only limited by the attached claims. Moreover, the drawings are not necessarily drawn to scale and are intended, unless other specifically stated, to conceptually illustrate aspects of the invention.

Figure 1 depicts a vehicle 100 suited to powered movement inter alia in a first direction of travel 105. It may for example be, but is not necessarily, a freight vehicle, a bus, a car or any of the previously enumerated types of vehicle or similar land-based means of transport. The vehicle 100 illustrated is moving along an itinerary 110 towards a destination 120.

The vehicle 100 has a cruise control for which the user chooses the destination 120 and a desired arrival time, instead of a desired speed as in a conventional cruise control. The cruise control then chooses the vehicle's speed along the itinerary 1 10. The choice is made on the basis of knowing the calculated journey time and the uncertainty of this journey time, based on stored statistics and on an estimated cost of a delay. Such delay costs may for example be predefined by the haulage operator which owns the vehicle or by the vehicle's driver. This may be effected by directly controlling the vehicle's cruise control or by indicating a recommended speed for the driver, in different embodiments. Where the speed is regulated by the cruise control, the driver may be given a means for accepting/rejecting the suggested speed and for interrupting speed regulation by the cruise control when the traffic situation so requires or the driver does for any reason find the respective speed inappropriate.

Figure 2 depicts statistics on journey time along the itinerary 1 10 to the destination 120. These statistics may in different embodiments be gathered, collated and stored by a data storage unit situated on board the vehicle 100 or outside, e.g. in an external server. These statistics may also in different embodiments comprise only journey times for the vehicle 100, journey times for vehicles of the same type as the vehicle 100, journey times for vehicles belonging to the same haulage operator as the vehicle 100. The statistics thus gathered may be used to calculate an average journey time for reaching the destination 120 along the itinerary 1 10. It is also possible for the probability of a certain deviation (due to external factors) from said journey time to be estimated and be for example represented by a density function for a spread of deviations from the average journey time. Such a density function may for example be called f(t), where t is the journey time. The density function describes the probability of actual journey time being within a certain range of time ti - t ₂ , as follows:

probability = J f f)dt for [t-, < t < t ₂ ] [formula 1 ] The density function may describe the probability of a certain actual journey time on the basis of a certain chosen target speed along the itinerary 1 1 0. The shape of the density function for the arrival time will vary depending on the chosen speed at which the vehicle is driven. I n one embodiment the density functions for a number of sections of the route to the final destination 120 may be summated, as also illustrated in Figure 4. These sections may vary in length from very short, e.g. 1 m, to quite long, e.g. 150 km, or longer. A typical length of a section might perhaps be one or several kilometres. The summation of the density functions may itself produce a composite density function for the whole of the remaining journey to the final destination, see formula 2 below. The probability of the respective actual journey time may then be multiplied by the corresponding estimated cost f _c (t) of arriving at the final destination 120 in this journey time t. This cost may for example comprise the cost of fuel, wages and possible costs of a delayed freight operation . This is also illustrated in Figure 6. The summated cost for all the possible arrival times according to the density function, F _c (t), will then be the function which needs to be minimised by optimum choice of target speed (and therefore journey time) on each section of the route (see formula 3).

The density function f _z (z) for actual journey time to the final destination 120 along a route with journey time X is arrived at by a calculation according to formula 2. The route with journey time Z comprises a first section with journey time X and a second section with journey time Y, which together constitute the route with journey time Z (see also Figure 6). The respective sections with journey time X and journey time Y each have their density functions f _x (y) and f _y (y), so the composite density function f _z (z) may be arrived at by calculating

fz (z) = L _∞ f ^x O - y fy(y dy [formula 2] Knowing the magnitude of this composite density function f _z (t) then makes it possible to calculate as follows a function F _c (t) which indicates the total cost of driving the vehicle 100 and reaching the destination 120 after a certain journey time t:

Fc(t) = !- _∞ f ^z ( )fc(t)dt [formula 3]

It is also possible to calculate the journey time t which will minimise the function F _c (t), i.e. the total cost, by min F _c (t). The journey time t thus arrived at may be set as a target journey time in certain embodiments. The arrival time t _a may be calculated by adding the journey time t to the starting time for the journey, as follows:

t _a = tstari + t [formula 4]

Said statistics about different journey times and the respective density functions pertaining thereto may be stored together with other information such as the date, time, day of the week etc. when they were gathered, making it possible to filter out measured values which are older than a certain limit value, e.g. five years, ten years or the like. This applies for example where altered routing, roadworks or altered speed limits affect speed on the itinerary. By filtering out statistics gathered on non-working days it is for example possible to achieve a more realistic picture of the peak traffic situation on a weekday.

Statistics may also, or alternatively, be stored with the time of the year, temperature and/or precipitation or weather conditions when they were stored. It is for example conceivable that journey time may be affected by slippery conditions, amounts of snow, fog, precipitation, blizzards etc. Journey time may also vary because of traffic situations and queuing in rush-hour traffic etc. at different times of the day. It thus becomes possible to filter statistics with respect to such conditions. It is also possible for one or more vehicle- specific parameters to be stored together with measured values, e.g. vehicle type, vehicle load, vehicle owner, vehicle driver, engine type, power output and/or various types of driver support systems (e.g. various types of cruise control). Filtering of statistics with respect to one or more of these parameters is thus made possible. Vehicle type here means type of vehicle, such as long-haul carrier, freight vehicle, car, motorcycle etc. Driving characteristics with regard for example to the (maximum permissible) speed, acceleration etc. of these vehicle types may be very different. Filtering of statistics with respect to vehicle type may therefore result in better forecasting of driving time. Similarly, journey time may vary depending on whether for example the vehicle is fully laden or unladen. Alternative embodiments may store, instead of travelling time, some other parameter which makes it possible to calculate travelling time, e.g. a vehicle's speed on a certain section of or at certain points along the itinerary, current times at which certain staging points along the itinerary are passed, or similar parameters.

5

Figure 3A depicts a vehicle 100, e.g. the vehicle previously depicted in Figure 1 , but as seen from a driver perspective.

In one embodiment the vehicle 100 may have a device 310 which may be provided with or 10 connected to a display screen 320. The display screen may also take for example the form of a touchscreen and therefore be usable as an input device in certain embodiments. This display screen may present information for the driver, as in the example illustrated in Figure 3B. The device 310 may also be provided, or communicate, with a position- determining unit 330 on board the vehicle, e.g. via the vehicle's communication bus, which 15 may take the form of one or more from among a cable, a data bus such as a CAN (controller area network) bus, an MOST (media oriented systems transport) bus or some other bus configuration.

The vehicle's speed will be regulated either by the driver directly via an acceleration control 20 315 or by the device 310 sending control signals to regulate the acceleration control to a certain calculated speed.

The device 310 may also, or alternatively, be arranged for wireless communication via a wireless interface in certain embodiments or be for example connected to a transmitter 340

25 which may be arranged for wireless communication. Such wireless communication may be based for example on any of the following technologies: Global System for Mobile Communications (GSM), Enhanced Data Rates for GSM Evolution (EDGE), Universal Mobile Telecommunications System (UMTS), Code Division Access (CDMA), (CDMA 2000), Time Division Synchronous CDMA (TD-SCDMA), Long Term Evolution (LTE), LTE

30 Advanced; Wireless Fidelity (Wi-Fi), defined by Institute of Electrical and Electronics Engineers (I EEE) standards 802.1 1 a, ac, b, g and/or n, Internet Protocol (IP), Bluetooth and/or Near Field Communication (NFC), or similar communication technology, in different embodiments, with a database 350, possibly via a base station or the like.

35 The vehicle 100 will be provided with or connectable to a position-determining unit 330 which may be adapted to determining the vehicle's geographical location on the basis of a satellite navigation system such as Navigation Signal Timing and Ranging (Navstar), Global Positioning System (GPS), Differential GPS (DGPS), Galileo, GLONASS or the like.

Position determination by satellite navigation is based on distance measurement with triangulation from a number of satellites 360-1 , 360-2, 360-3, 360-4 which continuously provide information in terms of time and date (e.g. in coded form), identity (which satellite 360-1 , 360-2, 360-3, 360-4 is transmitting), status and information about where the satellite is at each given time. GPS satellites 360-1 , 360-2, 360-3, 360-4 send information coded with code distinction, based for example on Code Division Multiple Access (CDMA). This means that information from an individual satellite 360-1 , 360-2, 360-3, 360-4 can be distinguished from information from the others, on the basis of a unique code for each of the satellites 360-1 , 360-2, 360-3, 360-4. The information thus provided may then be received by a GPS receiver adapted to doing so, e.g. the position-determining unit 330. The distance measurement is by the position-determining unit 330 measuring the difference in how long each respective satellite signal takes to reach the position- determining unit. The fact that these signals travel at the speed of light makes it possible to calculate how far away the respective satellite 360-1 , 360-2, 360-3, 360-4 is. As the positions of the satellites are known, since they are continuously monitored by some 15-30 ground stations situated mainly along or close to the equator, it is then also possible to calculate a location in terms of latitude and longitude by triangulation after determining its distance from at least three satellites 360-1 , 360-2, 360-3, 360-4. Altitude determination is possible in certain embodiments on the basis of signals from at least four satellites 360-1 , 360-2, 360-3, 360-4.

The device 310 and/or the position-determining unit 330 are also arranged to have access to map data, particularly map data related to the respective location determined of the vehicle 100. The device 310 and/or the position-determining unit 330 may also chart the determined location of the vehicle 100 against map data. The vehicle's location on the itinerary 1 10 may thus be detected in certain embodiments. This position determination may take place continuously at certain predetermined or configurable intervals of time, in different embodiments.

Figure 3B depicts an example of a display screen 320 which may also serve as an input device in certain embodiments. Such an input device may however be separate and be provided with a keyboard, one or more buttons or the like. In the example illustrated the driver may indicate his/her desired destination and desired arrival time. In certain embodiments he/she may also indicate how important it is to arrive by the desired arrival time, on a scale of from 1 to 5. This is merely one example, it is of course possible to use some other form of gradation such as two steps (important/not so 5 important), three steps (urgent/normal/arrival time not significant) etc. Alternatively, the economic cost of any delay in delivery, e.g. as a result of fines or the like, may be indicated.

In certain embodiments the degree of importance fed in may also be charted against an 10 expectation value based on statistical information, e.g. that high importance means the vehicle 100 reaching the destination 120 on time in 98% of cases, a lower degree of importance means doing so in 90% of cases, and so on. Here again these are merely examples of possible levels. High degree of importance might for example mean reaching the destination on time in 90% of cases; intermediate degree of importance doing so in 15 70%) of cases, low degree of importance doing so in 10% of cases, to mention another example of various conceivable but non-limitative levels of importance.

Figure 4 depicts an example where the itinerary 1 10 between the vehicle's location and the destination 120 is divided into stages 410 each with a target staging point 420. For 20 each stage 410 an average journey time and a spread value for this average journey time may be calculated on the basis of saved statistics. When the vehicle reaches the staging point 420 pertaining to each stage 410, a comparison may be made between the forecast and actual time of passing it.

25 It is thus possible in certain embodiments for the calculation of a vehicle speed for the vehicle 100 to reach the destination 120 by the desired arrival time to be corrected on the basis of the actual journey time at which the staging point 420 is reached as compared with a previously forecast time for reaching it.

30 It thus becomes possible, if it seems that a staging point 420 is reached with a disproportionately large margin relative to the desired arrival time at the destination 120 and the degree of importance of reaching the destination on time, to make a fresh speed calculation leading to reduced speed and consequently lower fuel costs.

35 Figure 5A depicts an example of the display screen 320 in an embodiment where the itinerary 1 10 is presented for the driver of the vehicle 100. The screen may for example also show (suggested) break locations, filling stations or the like. I n certain embodiments information may be acquired from the vehicle's cruise control about the driver's actual driving time and/or daily rest. This involves adding up permissible actual driving time, e.g. 3.5 to 4.5 hours, depending on legal requirements but also on employer policy which might result in shorter driving time than the maximum allowed by law.

I n the example illustrated, the driver's driving time is calculated to end immediately after passing the two suggested break locations A and B. In certain embodiments further information may also be presented, as in Figure 5B, which gives more information on each of the possible break locations.

Figure 6 depicts an example of the relationship between driving time and cost and illustrates how cost may be minimised by adapting the arrival time at the destination . This illustration is merely an arbitrary example which applies in certain particular circumstances. The slopes of the two continuous lines will vary inter alia with the vehicle's fuel consumption, air resistance to the vehicle etc., for the curves which respectively indicate reduced costs due to lower speed and possible damages or loss of goodwill due to delayed arrival. Other examples of increased cost due to delayed arrival might be the consignee having closed for the day at a certain time, forcing the driver to wait until the next day to be able to unload, etc.

The example in Figure 6 is simplified and covers only costs for a particular freight operation without regard to knowledge of journey time uncertainty based on external factors such as queuing and other speed-limiting occurrences, as in Figure 2. There is a probability of such a possible longer journey time which, depending on the degree of importance of reaching the final destination before a certain time, may cause a raised speed of the vehicle, or the opposite, with a view to minimising or at least reducing the composite cost. I n many cases it may be difficult to estimate increased costs arising from a delay. In certain embodiments it is therefore possible to indicate instead the degree of importance of arriving by a certain time, e.g. high or low, or a desire to be on time in 95% of cases, for example. Figure 7 illustrates an example of an embodiment for the invention, in the form of a flowchart of a method 700 for calculating and adapting the speed of a vehicle 100 for a desired arrival time at a destination 120. In certain embodiments the method 700 may for example comprise determining at least one vehicle-specific characteristic of the vehicle 100 such as vehicle type, vehicle load, vehicle owner, vehicle driver and/or various types of vehicle driving support systems (e.g. various types of cruise control).

The method 700 may also comprise gathering of information related to an expected halt for the vehicle 100 before reaching the destination 120, such as needing replenishment of fuel or of a urea-based liquid intended for exhaust cleaning and/or the driver needing a break according to rules on driving and rest times and data from a cruise control on board the vehicle, in certain embodiments.

In certain embodiments the method 700 may also comprise acquiring information, e.g. starting point and departure time for a vehicle train which travels along at least part of the itinerary 1 10 towards the destination 120, enabling the vehicle 100 to join the train.

The method 700 may further comprise acquiring information about conceivable locations along the itinerary 110 for effecting the expected halt, selecting locations for expected halts for the vehicle 100 and presenting for the vehicle's driver this selection of suggested halt locations. This selection may then be based on acquired information about rules on driving and rest times, and/or the vehicle's fuel requirements.

To be able to calculate and adapt the vehicle's speed in a correct way, the method 700 may comprise a number of steps 701 -710, although it should be noted that some of the steps here described are part of only certain alternative embodiments of the invention or that certain steps may be performed according to various alternative embodiments. The steps 701 -710 described may also be performed in some other chronological order than that suggested by their numerical order, and certain of them may be performed in parallel with one another. At least some of steps 704-710 may be performed iteratively so that the vehicle speed calculation is updated for each iteration, thereby correcting the calculation continuously at any desired intervals of time, irrespective of any target staging points 420 along the itinerary 1 10. The method 700 comprises the following steps:

Step 701

The vehicle's destination 120 is registered, e.g. by the vehicle's driver, the vehicle's owner or the like. This registration may be effected on board the vehicle in certain embodiments or from a location at a distance outside the vehicle, e.g. via a wireless interface on a mobile telephone, computer or the like. The destination may for example be chosen from a list of destinations and be fed into a text-based programme or be marked on a map, or in some other similar way. Step 702

A desired arrival time at the destination 120 is registered, which may likewise be effected by the vehicle's driver, the vehicle's owner or the like, on board or from outside the vehicle.

Step 703

A degree of importance of reaching the destination 120 by the registered 702 desired arrival time is set.

This degree of importance may for example be indicated by the vehicle's driver or owner or be tied to the destination 120, in different embodiments. Said degree of importance may then be taken from a register in which the degree of importance is associated with the vehicle's destination, or it may be a preset value. The degree of importance may also be associated for example with the consignee's stock level so that detection of a stock level below a certain limit value may lead to a high/raised degree of importance, etc. Such stock level data may for example be obtained from the consignee's stock management system or from the consignee.

In a non-limitative example, a high degree of importance of reaching the destination 120 by the desired arrival time might mean arriving on time in 90% of cases + 10%, a normal degree of importance might mean doing so in 70% of cases + 20%, a low degree of importance might mean doing so in 50% of cases + 30%, for example.

Step 704

The vehicle's geographical location is detected. In certain embodiments its location may be determined by means of a position-determining unit 330 by satellite-based positioning.

Such satellite-based positioning may comprise for example GPS, Navstar, DGPS, Galileo, GLONASS or the like.

In other embodiments the vehicle's geographical location may for example be detected by its driver indicating its location, by the location being read from the vehicle's trip gauge, by triangulation of radio signals from base stations situated at known locations, or in some other similar way. Step 705

A current time is detected, e.g. by reading a clock on board the vehicle, by driver input or in some other similar way.

The current time detected may comprise a time of day, a day of the week, a week, a month, a year and/or years, in different embodiments.

Step 706

The itinerary 110 from the vehicle's detected 704 geographical location to the destination 120 is determined.

The itinerary 1 10 may be determined as the route which the driver plans to follow between the vehicle's detected 704 geographical location and the destination 120.

Determining the itinerary to the destination may also comprise determining a maximum permissible speed on the itinerary or on different sections 410 of the itinerary, in certain embodiments, and/or other speed limits pertaining to the itinerary. Step 707

The distance between the vehicle's detected 704 geographical location and the destination 120 along the determined 706 itinerary 1 10 is calculated.

Step 708

Statistical information about average journey time to the destination 120 along the itinerary 110, and a density function for a spread of deviations from this average journey time, are acquired.

The acquisition of statistical information may in certain embodiments be filtered with respect to the determined vehicle-specific characteristic of the vehicle 100, so that the information is acquired from vehicles which have corresponding vehicle-specific characteristics, e.g. trucks in cases where the vehicle 100 is a truck; engine power, engine type, cargo weight etc., but also available forms of driver support such as cruise control. By this filtering of the vehicle-specific characteristic of the vehicle 100 it is possible to arrive at a probability of achieving a certain journey time, e.g. 45 minutes, at a certain target speed such as 79 km/h on the whole itinerary 1 10 to the destination 120. In certain embodiments the itinerary to the destination may instead be divided into sections 410 and a probability be arrived at of achieving a certain total journey time, e.g. 45 minutes, at a certain first target speed such as 80 km/h on the first section 410-1 and a second target speed such as 78 km/h on the second section 410-2.

This acquisition of statistical information about a certain section of the itinerary may also be filtered with respect to the estimated current time so that the information is acquired for average journey times and deviations from them which have been registered at a corresponding current time.

Step 709

The speed for the vehicle 100 to reach the destination 120 by a desired arrival time with as low fuel consumption as possible is calculated on the basis of the calculated 707 distance to the destination 120, the difference in time between desired arrival time and detected 705 current time, the attributed 703 degree of importance of reaching the destination by the desired arrival time and the acquired 708 statistical information and the density function.

In certain embodiments an attributed 703 high degree of importance of reaching the destination 120 by the desired arrival time means that the vehicle speed calculation involves choosing a speed which adds to the desired arrival time a time margin which is related to the magnitude of the acquired 708 density function for a spread of deviations from the average journey time. It is also possible to choose a speed which adds to the desired arrival time a time margin which is related to the magnitude of the acquired spread of deviations from the average journey time, e.g. proportional to said magnitude, in certain embodiments.

The vehicle speed calculation may be based on the acquired vehicle-specific characteristic of the vehicle 100, e.g. maximum permissible speed or highest possible speed for its vehicle type in the respective topography, in certain embodiments.

The vehicle speed calculation may also be based on acquired statistical information which is filtered with respect to the time at which the statistical information for a certain road section 410 was stored, relative to a time at which the vehicle 100 passes or is calculated to pass the respective road section 410. The calculated vehicle speed may be limited by the maximum permissible speed on a certain road section 410.

The vehicle speed calculation may take account of the journey time lengthening which the expected vehicle halt causes, in certain embodiments.

In certain embodiments the method 700 comprises also gathering current information about the practicability of the itinerary 110, which may then be taken into account in the vehicle speed calculation.

Such gathering of current information about the practicability of the itinerary may comprise average journey time and expected density function for a spread of deviations from this average journey time for a vehicle which at the respective time passes the itinerary 1 10, from a news service which provides such information, information about traffic accidents or queuing and/or information about the current state of roads, based for example on rain sensors or thermometers on board the vehicle or acquired from a news service which provides this information, or obtained from a vehicle travelling in the opposite direction which has passed at least one section of the itinerary, via a wireless interface by vehicle-to- vehicle communication, in certain embodiments.

In certain embodiments the itinerary 1 10 may be divided into stages 410 each with a target staging point 420. The vehicle speed calculation for the vehicle 100 to reach the destination 120 by a desired arrival time will be corrected on the basis of the actual journey time at which each staging point 420 is reached as compared with a previously forecast journey time for reaching the respective staging point, in certain embodiments. Certain such embodiments may further comprise attributing a degree of importance of reaching the respective staging point 420 by an estimated time for passing it, and the vehicle speed calculation for the vehicle to reach the destination 120 by the desired arrival time will be corrected on the basis of the actual journey time at which each staging point 420 is reached as compared with the previously forecast time for passing it and the attributed degree of importance of reaching it by the forecast passing time.

The vehicle speed calculation for the vehicle 100 may in certain embodiments be adapted to any vehicle train which travels along at least part of the itinerary 110 towards the destination 120, and to the respective train's departure time or passing time, so that the vehicle 100 can join the train. Step 710

This makes it possible for the vehicle 100 to be driven at the calculated 709 speed.

In certain embodiments the calculated 709 vehicle speed is presented for the driver on board the vehicle 100, e.g. on a display screen or the like. In certain embodiments the driver may him/herself regulate the calculated 709 vehicle speed if it is inappropriate, and may for example raise or lower it. In certain further embodiments, making it possible for the vehicle 100 to be driven at the calculated 709 speed comprises generating control signals for the vehicle to be driven at this calculated speed.

Figure 8 illustrates an embodiment of a device 310 for calculating and adapting the speed of a vehicle 100 for a desired arrival time at a destination 120.

This device 310, which may be on board the vehicle 100, is configured to perform at least some of the previously described steps 701-710 of the previously described method 700 for calculating and adapting the vehicle's speed to the desired arrival time.

To be able successfully to calculate and adapt the speed of the vehicle 100 to the desired arrival time, the device 310 comprises a number of components which are described in more detail below. Certain of the subcomponents described are present in some, but not necessarily all, embodiments. There may also be in the device 310 further electronics which are not entirely necessary for understanding the function of the device 310 according to the invention and are therefore omitted from Figure 8 and from this description. The device 310 comprises a processor circuit 820 adapted to registering the vehicle's destination. The processor circuit is further adapted to registering a desired arrival time at the destination 120. The processor circuit is also adapted to attributing a degree of importance to reaching the destination 120 by the desired arrival time. The processor circuit is also adapted to detecting the vehicle's geographical location and current time. The processor circuit is further adapted to determining an itinerary 1 10 from the vehicle's detected geographical location to the destination 120. The processor circuit is also adapted to calculating a distance between the vehicle's location and the destination 120 along the itinerary 110 determined. In addition, the processor circuit is also adapted to acquiring statistical information about average journey time to the destination 120 along the itinerary 1 10. The processor circuit is adapted to acquiring statistical information about average journey time to the destination 120 along the itinerary 1 10, and a density function for a spread of deviations from this average journey time. The processor circuit is further adapted also to calculating a vehicle speed for the vehicle 100 to reach the destination 120 by desired arrival time with as low fuel consumption as possible, this speed calculation being based on the calculated distance, the difference in time between desired arrival time and detected current time, the attributed degree of importance of reaching the destination 5 120 by the desired arrival time, and the acquired statistical information and the density function, whereby the processing circuit makes it possible for the vehicle 100 to be driven at the speed calculated.

The processor circuit 820 may for example take the form of one or more central processing0 units (CPUs), microprocessors or other logic suited to interpreting and applying instructions and/or to reading and writing data. The processor circuit may handle data for inflow, outflow or processing of data, comprising also buffering of data, control functions and the like. 5 The device 310 may also comprise a signal receiver 810 which may be adapted to receiving a location determination for the vehicle 100 from a positioning unit 330 on board the vehicle, in certain embodiments. The signal receiver 810 may further be adapted to receiving data fed in from an input device 320. The signal receiver 810 is also adapted to receiving statistical information from a database 350.

0

The device 310 may further comprise also in certain embodiments a memory unit 825 adapted to temporarily or permanently storing information related to the method 700.

The memory unit 825 may for example take the form of a memory card, flash memory,5 USB memory, hard disc or other similar data storage units, e.g. any from among ROM (read-only memory), PROM (programmable read-only memory), EPROM (erasable PROM), flash memory, EEPROM (electrically erasable PROM), etc., in different embodiments. 0 The device 310 may further in certain embodiments comprise also a transmitting circuit 830 adapted to sending a control signal for controlling the vehicle's speed to a speed control 315 via a wireless or wired interface. In certain embodiments the transmitting circuit 830 and also the signal receiver 810 may be part of the device 310 so as to form a composite unit.

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The invention further comprises a computer programme for calculating and adapting a vehicle's speed for a desired arrival time at a destination 120, by conducting a method 700 comprising at least some of the previously described steps 701 -710 when the programme is executed in a processor unit 820 in a device 310. This device 310 may be on board or outside the vehicle 100, in different embodiments. The method 700 according to steps 701 -710 for calculating and adapting the speed of a vehicle 100 for the desired arrival time may be implemented by one or more processor circuits 820 in the device 310, in conjunction with computer programme code in a nonvolatile data support, in order to perform one, several, certain or all of the method steps 701 -710 described above. A computer programme may thus comprise instructions for performing steps 701-710 when the programme is loaded in the processor circuit 820 in the device 310.

Certain embodiments further comprise also a system for calculating and adapting the speed of a vehicle for a desired arrival time at a destination 120. This system comprises an input device 320 adapted to registering the vehicle's destination 120 and desired arrival time. The system comprises also a position detector 330 adapted to detecting the vehicle's geographical location. The system also comprises a database 350 adapted to storing statistical information about average journey time to the destination 120 along the itinerary 110, and a density function for a spread of deviations from this average journey time. The system comprises also a device 310.

Some embodiments of the invention comprise also a vehicle 100 provided with at least part of the system for calculating and adapting a vehicle's speed for a desired arrival time at a destination 120. This vehicle 100 therefore has an input device 320 adapted to registering the vehicle's destination 120 and desired arrival time; a position detector 330 adapted to detecting the vehicle's geographical location; a database 350 adapted to storing statistical information about average journey time to the destination 120 along the itinerary 1 10, and a density function for a spread of deviations from this average journey time; and a device 310 for calculating and adapting the vehicle's speed for a desired arrival time at a destination 120, as described above.

Figure 9 illustrates two different scenarios where the outcomes will be different as a result of different spreads of the density function f _x (t). The whole itinerary is here designated z and comprises a first section x and a second section y. These respective sections x and y and the combined journey z may be of any length, e.g. one or more decimetres, one or more metres, one or more hundreds of metres, one or more kilometres, one or more tens of kilometres, one or more hundreds of kilometres, one or more thousands of kilometres etc. They may also be of equal or different lengths, in different embodiments.

I n the example illustrated, scenario 1 and scenario 2 may for example be respective density functions f _x (t) and f _y (t) at different times of the day, on different days of the week, at different times of the year or the like.

I n scenario 2, if the outcome becomes a short journey time (in the left part of the bell shape) on the first section x, it is possible to drive gently, i.e. with lowered vehicle speed, on the remainder of section y to the destination 120. This is because the spread f _y (t) for the second section y is narrow in this scenario, so there is no need for any greater safety margin to maintain relative certainty of reaching the destination 120 by the arrival time determined. I n scenario 1 the outcome on the second section y will be uncertain because of the broad density function fy(t), making it necessary to adopt a high speed on the first section x in order to have a margin for coping with the great uncertainty on the second section y. In this example the f _x (t) and fy(t) density functions will be given a certain target speed on the respective x and y sections. The spread is decided partly by the target speed chosen but also by prevailing traffic situations, weather, etc.

Moreover, in certain embodiments, different target speeds may be used for the x and y sections, depending for example on different speed limits on the respective sections, power output limitations of the vehicle 100 such that the target speed cannot be maintained uphill, for example. The composite whole itinerary z may in different embodiments comprise any desired number of sections x, y. The adaptation of the vehicle's speed to a desired arrival time at the destination 120 may also comprise adapting the respective target speeds for sections x, y and recurrent updating of the calculation of remaining travelling time to the destination 120 in order to reach it by the desired arrival time with as low fuel consumption as possible.