FIELD OF THE INVENTION

The present invention relates to a system for estimation of a remaining safe driving and to methods for estimation of a remaining safe driving time and remaining safe driving distance for a driver of a vehicle.

BACKGROUND OF THE INVENTION

More and more traffic accidents happen due to a driver's lack of attention. One common reason for the lack of attention is the fatigue and drowsiness of a respective driver.

Although there are laws in some countries regarding the maximum continous driving time of a driver, these do in general only concern professional drivers and are also only based on averages and do not reflect the true fatigue or drowsiness of a driver. So, even if a driver follows these laws this does not necessarily mean that he/she is fully awake and alert.

In order to determine a state of drowsiness several drowsiness detection systems have been developed and also already included in vehicles including private cars. For example, US 2009/0268022 Al describes a system for estimating the wakefulness level of a driver based on the eye movement, blinking or other behaviors that may indicate the drowsiness of the driver.

These systems warn the user if he/she is getting tired and suffers from a lack of awareness and recommend to rest. However, these systems do not allow for a long term planning, since they only recognize the drowsiness already present.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a system and a method that allow a driver of a vehicle to know the time and/or distance he/she may drive safely in an awake and aware state.

According to an aspect of the present invention a system for estimation of a remaining safe driving of a driver of a vehicle is provided, with:

a processing unit,

a clock, a speed data providing device,

a memory device, and

a user interface,

wherein the clock, the speed data providing device, the memory device and the user interface are able to send respective data to the processing unit,

the processing unit is able to receive the respective data from the clock, the speed data providing device, the memory device and the user interface, and

wherein the processing unit is designed to estimate the remaining safe driving time based on the received data, preferably wherein the processing unit is designed to estimate the remaining safe driving distance based on the received data.

According to another aspect of the present invention a method for estimation of a remaining safe driving time for a driver of a vehicle is provided, with the following steps:

receive sleep data of the driver,

- determining a continuous driving time,

determining the time of day,

estimation of the remaining safe driving time based on the sleep data, the time of day and the continuous driving time.

According to another aspect of the present invention a method for estimation of a remaining safe driving distance for a driver of a vehicle is provided, with the following steps:

estimation of a remaining safe driving time for the driver of the vehicle, determining the speed of the vehicle,

estimation of the remaining safe driving distance based on the remaining safe driving time for the driver and the speed of the vehicle, wherein the speed is preferably determined based on GPS data.

The term "remaining safe driving" as used within the context of the present invention is to be understood as encompassing the remaining safe driving time and the remaining safe driving distance. This term may therefore either indicate how long or how far a driver may still drive safely and shall be understood in this general way.

The term "speed data providing device" as used within the present invention is to be understood as any suitable device that is capable of detecting the speed of the vehicle and further capable of providing this speed data to another device. This can for example be done by built-in measuring systems of the vehicle and provided via CANBUS or preferably via a GPS device.

The term "GPS device" as used within the present invention is to be understood as any suitable device that is capable of receiving GPS satellite signals, translate them to position data, preferably in the form of coordinates, and to provide these data to another device.

The term "sleep data" as used within the present invention is to be understood as any data relating to the sleep of the driver, like but not limiting to sleep quality and duration, preferably sleep duration within a determined past time interval, e.g. within the last 24 hours.

With the help of the system and the methods according to the present invention a driver may get information about the remaining safe driving time and distance based on his/her own estimated level of drowsiness. For this the system receives information about the sleep data of the driver, for example by the driver entering his/her own sleep data via the user interface into the system, e.g. how long he/she slept in the past 24 hours. This data may be used by the system as one parameter contributing to drowsiness. The system may further estimate another contribution to the drowsiness of the driver based on the time of day, which can be derived via the clock. Due to the so-called circadian rhythm, a basic drowsiness alters during the day. Also, the system may recognize the continuous driving time of the driver via the position and/or speed data achieved from the speed data providing device, like a GPS device, and preferably stored via the memory device. The longer a driver drives the more he/she gets tired and the drowsiness increases.

Based on these different data the system may estimate an overall state of drowsiness and as a result the remaining safe driving time since each of these mentioned parameters contribute to the total drowsiness of the driver. Further, based on the known speed, preferably the average speed of the vehicle, the system may also beneficially estimate the remaining safe driving distance. Accordingly, the system and the methods allow the information of the driver how long and how far he/she can still drive safely. Therefore, the user may be informed via the user interface, e.g. by showing the remaining safe driving time and/or distance. What is considered as "safe" within the present invention may depend on the individual driver. If for example a drowsiness is expressed as a relative value, an overall drowsiness of 80% might be considered as still safe and may form a suitable threshold, for example. According to an embodiment of the system, the system further comprises a gyroscope device, wherein the gyroscope device is able to send data to the processing unit and the processing unit is able to receive the data from the gyroscope device.

According to another embodiment of the method for estimation of the remaining safe driving time, the method further comprises the step of assessing the lateral movement of the vehicle over a defined time, wherein the estimation of the remaining safe driving time is further based on the assessed lateral movement.

Via the gyroscope the assessment of the lateral movement of the vehicle is possible. Thereby swerving actions can be detected and recorded, preferably with the processing unit and the use of the memory device. By these detected, and preferably analyzed swerving patterns another parameter is accessible that allows an estimation of the overall drowsiness. For example, if in a predetermined time interval an increased amount of swerving actions is detected, the driver probably suffers from an increased drowsiness. Use of these data can for example be made by recording all the swerving actions and their intensity, e.g. via the amplitude, and thereby deriving a separate drowsiness parameter that is part of and contributes to the estimated overall drowsiness of the driver.

According to another embodiment of the system, the user interface comprises an alarm unit for giving an alarm to the driver. Thereby, an easy way of informing the user of the drowsiness, e.g. if a certain predetermined threshold is passed is possible. For example, a warning of the driver may occur if there are only one or two hours remaining safe driving time left, or if there are only 100 km safe driving distance remaining.

According to another embodiment of the system, the system further comprises a navigation system, wherein the navigation system is able to send and receive data to and from the processing unit and the processing unit is able to receive and send data from and to the navigation system. With a navigation system it is possible that the system may use the estimated remaining safe driving distance to show the driver where he may still drive.

Therefore, the navigation system preferably comprises map data. Further, with the aid of such a navigation system it is possible that based on the estimated remaining safe driving distance the navigation system may find and show the driver next possible service areas, like rest stops and/or hotels, where he/she may rest and/or sleep and that lie in a distance that can be reached before the driver gets to tired or drowsy.

According to another aspect of the present invention, a system for detection of drowsiness of a driver of a vehicle is provided, with a system for estimation of a remaining safe driving according to the present invention. According to an embodiment of the method for estimation of a remaining safe driving time, the method further comprises the step of determining a resting time of the driver, wherein the estimation of the remaining safe driving time is further based on the resting time. By including also the resting times of the driver in the estimation of the overall drowsiness, the estimation gets more accurate since any pauses or longer stops the driver may have taken are included in the estimated remaining save driving time. For example, if the driver decides to stop for 30 minutes, the system and method allow to include these data of the stop as well as its duration in the estimation of the remaining safe driving time such that the driver may be considered more awake or alert and therefore less drowsy.

According to an embodiment of the method for estimation of a remaining safe driving time, the time of day is used to determine the drowsiness based on the circadian- rhythm.

According to an embodiment of the method for estimation of a remaining safe driving distance, the estimation of the remaining safe driving time is realized according to the method for estimation of the remaining safe driving time according to the present invention.

According to another aspect of the present invention, computer programs are provided that comprise program code means for causing a computer to carry out the steps of any one of the afore mentioned methods when said computer program is carried out on a computer.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other aspects of the invention will be apparent from and elucidated with reference to the embodiment(s) described hereinafter. In the following drawings

Fig. 1 shows a schematic representation of a system according to the present invention,

Fig. 2 shows a schematic illustration of a circadian rhythm,

Fig. 3 shows a schematic illustration of a determination of continous driving time and resting time according to the methods of the present invention,

Fig. 4 shows a schematic illustration of the usage of the estimated remaining safe driving distance, and

Fig. 5 shows a schematic illustration of the method for determining and using the estimated safe driving distance according to the present invention. DETAILED DESCRIPTION OF THE INVENTION

An embodiment of a system according to the present invention is shown throughout and described with the help of Figs. 1 to 5 and is designated in its entirety by the reference numeral 10. System 10 is preferably part of a drowsiness detections system (not shown) and is preferably arranged within a vehicle (not shown).

The system 10 as shown in Fig. 1 comprises a processing unit 12, a clock 14 and a speed data providing device, here a GPS device 16. In the present embodiment the GPS device 16 is part of a navigation system 18. However, this is not meant as a limitation and systems according to the present invention wherein the navigation system 18 and GPS device 16 are separate devices, either communicating with another or with the navigation system 18 having a separate (additional) GPS device, lie also within the scope of the present invention. System 10 further comprises a memory device 20 and a user interface 22.

The memory device 20 may store all the data relevant for the system 10 and the methods according to the present invention, like but not limiting to speed of the vehicle, current time of a task, e.g. driving or resting, continuous driving time, resting time, swerving patterns of the vehicle.

The user interface 22 in the present embodiment comprises a device-user interface 24 for providing data or information to the user and a user-device interface 26 for allowing the system to receive information/data from the driver. Aside from this special embodiment, user interfaces only comprising a device-user interface 24 or a user-device interface 26 lie also within the scope of the present invention. For easy notification of a driver, the user-device interface 26 comprises an alarm unit 28.

The system 10 further comprises a gyroscope device 30. This gyroscope device 30 is arranged in the system 10 and the vehicle in that way that it may detect any lateral movements of the vehicle comprising system 10. Examples for such movements are swerving actions caused by abrupt steering and correction of the steering by the driver.

All mentioned devices are able to send data to the processing unit 12 and may also receive data from the processing unit 12. The processing unit 12 is therefore able to send and receive the respective data to and from the devices. This is indicated by arrows 32, 34, 36, 38, 40, 42 and 44.

For estimating the remaining safe driving time, the processing unit 12 receives the current time of the day from the clock 14. Based on the time the processing unit 12 can asses the level of drowsiness D _C R(t) that naturally alternates during the day based on the circadian rhythm. An exemplary visualization for this circadian rhythm is shown in Fig. 2. Therein, the abscissa 46 shows the time of the day while the ordinate 48 shows the level of drowsiness. Further in Fig. 2 an exemplary threshold 50 is indicated by dashed line 52, the usage of which will be explained later.

The system 50 may further request the driver to enter his sleep data, like the hours of sleep he/she got within the last 24 hours. This can for example be done via the user interface 22, especially via the user-device interface 26. The latter may comprise a keyboard or may be realized via a touch screen device, which may be included in the vehicle's system, for example. Based on this sleep data, the processing unit 12 may determine another level of drowsiness D _s i _ee p(t), which depends on the momentary constitution of the driver.

Due to the transfer of data from the GPS device 16 to the processing unit 12, the latter may get and record speed data and preferably store this data in the memory device 20. Based on this speed data the processing unit 12 with the memory device 20 is able to determine the continuous driving time ti. Also, the processing unit is able to determine the rest time t ₂ . Based on these times, the processing unit 12 may then determine another level of drowsiness based on the net continous driving time D _nc d _t . This drowsiness parameter is given by equation (I):

^D «cd _t = ^a A - ^a 2 ^f 2 Equation (I)

Therein, ai and a ₂ are constant values based on empirical data that may also be adjusted according to a respective driver. In a preferred embodiment, a ₂ is equal to ai if the resting time t ₂ is less than 15 minutes and four times ai if t ₂ is more than 15 minutes.

An exemplary illustration for determining ti and t ₂ is shown as a chart in Fig. 3. Therein the steps processed by the processing unit 12 in order to determine and t ₂ are shown. After a complete passing through of the steps shown therein, t _\ and t ₂ may be stored in the memory device 20 and the passing through of this steps for recording ti and t ₂ may start over. All the stored times and t ₂ can be respectively accumulated and used for determining the drowsiness value D _nc dt according to the present invention. In this exemplary embodiment, the vehicle is considered driving when a speed of at least 5 km/h is detected via the GPS device 16.

Another aspect that may be used as an indicator for determining the drowsiness of the driver is the afore mentioned lateral movement of the vehicle, like swerving patterns, detectable via the gyroscope device 30, for example. These lateral movements are submitted by the gyroscope device 30 to the processing unit 12 in form of output signals corresponding to the yaw rate, for example. Then the happen times N, indicating the number of times wherein a threshold P for this yaw rate is passed within a time duration τ by these output signals, may be used as an indicator of the magnitude of the lateral movement. Based on this value N and therefore on the vehicle lateral movement another level of drowsiness D _v i _m may be determined by the processing unit 12. This may be done according to an equation (II):

D _vlm = a ₃ ∑N Equation (II)

t _w

Therein, a ₃ is also a constant value based on empirical data and t _w is a time window that is used for monitoring the lateral movements. That is to say that all the lateral movements that occur in t _w are considered. Exemplary values for t _w may be in the range of minutes but can also be several hours, since t _w may correspond to the journey time. The threshold P is in one example set to 1.5 deg/s. The time duration value τ may be in the same or also another example set to 2 seconds. In some embodiments, it may be desired that only lateral movements are considered if the vehicle speed is higher than a predetermined value, like 80 km/h, for example. In an exemplary case ai is 1/4, a ₂ is 1 and a ₃ is 1.

All the aforementioned drowsiness values may be used to estimate an overall drowsiness D. This is achieved by equation (III):

D = D _CR(t) + D _sleep(t) + D _ncdt + D _vlm Equation (III)

It has to be noted that all the terms in this drowsiness D are dependent on the current time or time of the current task, like driving, resting etc., t. The sum of D _C R _(t) and D _s i _eep(t) can be considered as a baseline of drowsiness used in the present invention.

For estimating the remaining safe driving time tRSD a certain threshold D _a i _arm is set in the system 10. When, for example, a relative drowsiness value is used, meaning where D can be anything between 0 and 100 for example, D _a i _arm can be set to a value of 80. This would correspond to the threshold 50 of Fig. 2. Reaching or passing this threshold of drowsiness by D would indicate that the driver has reached a drowsiness level where it is recommend to take a rest soon. For determining the remaining time before this level D _a i _arm is reached the difference between D _a i _arm and D is divided by ai to achieve t _RS D, in the present embodiment. This is illustrated by Equation (IV):

^D alarm ^~ ( ^D CR( _t ) + ^D _S leep{t) ) ^" < k + ^a ih ^~ < Σ ^N

t _RSD = = '- Equation(IV) α _γ α _γ

Either in the absence of lateral movements detected by the gyroscope device 30, for example, or if a simpler determination of t _RS D is desired, the equation of Equation (IV) for t _RS D may be simplified to t _RS D-2, shown in Equation (V): D alarm ^~ (PcR(t) ⁺ ^ sleep (t)) ^~ + ^α ΐ ^ , . _n

^ Equation (V) α _γ

This remaining safe driving time t _RS D-2 is based on the time of the day, e.g. the circadian rhythm, the sleep data of the driver, e.g. the sleeping hours of the driver, and the net continuous driving time. t _RS D-2 may further be used, if any detected lateral movements are only considered for the estimation of the drowsiness if they happen repeatedly in a predetermined time window. For example, if the driver does at least two swerving actions within a time window of 15 minutes. In other words, the contribution of the detected lateral movements to the overall drowsiness, and in the consequence to the remaining safe driving time, may be only considered short-term. Another simplification can be done if further the resting time t ₂ shall not be considered. This leads to the an estimated remaining safe driving time tRSD-3, shown in Equation (VI):

D * alarm ^~ (t) ⁺ ^sleep(t)) ^~ * l „ .

Equation (VI) tRSD-3 is accordingly based on the time of the day, the sleep data of the driver and the continuous driving time In other words, t _RS D-3 is for a scenario where no lateral movement shall be considered and the driver drove without a break, for example.

After estimating the remaining safe driving time according to the present invention, this remaining safe riving time can be provided to the driver via the user interface 22. Further, it can be used by the system 10 to estimate a remaining safe driving distance dRSD- For this, the speed of the vehicle is determined via the GPS device 16 and averaged to an average speed v _av . This may for example be done by storing the current speed repeatedly in the memory device 20 and calculating the average over these values over a certain time window. The remaining safe driving distance is then the product of average speed and remaining safe driving time, shown in equation (VII):

= ^v av * Equation (VII)

This remaining safe driving distance can then either be provided to the driver via the user interface 22, i.e. the device-user interface 24, or be used together with the navigation system 18. Therein, via the map data included in the navigation system 18 and based on the current position, derivable from the GPS device 16, the remaining safe driving distance can be visualized. For this, any visualization means present in the navigation system 18, the vehicle itself, the user interface 22 etc. may be used. Further, the navigation system 18 or the system 10 in general may provide suggestions for service areas that shall be used as the next stop. Non-limiting examples for such service areas are rest stops, hotels, restaurants, gas stations, shops etc. These suggestions may further be based on additional user data and preferences, like minimum standard of the hotel, kind of the rest stop, facilities present at the rest stop etc.

In the illustration of Fig. 4 a car 54 on an expressway 56 is shown. For this car 54 an estimated remaining safe driving distance t _RS D along the expressway 56 is shown by an arrow 58. The navigation system 18 may for example illustrate this in a similar way as shown in Fig. 4, e.g. via an arrow, a colored road etc. Further, it may check whether there are service areas along the expressway 56 that preferably fit to the preferences entered by the driver in the system 10 (if any of those are present). If, like in the present example, no such service areas are present along the expressway 56, the system 10, in this example the navigation system 18 may also consider leaving the expressway 56 via an exit to a side road 60. For this, also the remaining safe driving distance is illustrated via an arrow 62. This driving distance 62 may vary from the distance 58, since different, i.e. lower, maximum speeds are allowed on the side road 60 compared to the expressway 56 and it is therefore to be expected that the driver may drive not as far within the estimated remaining safe driving time as on the expressway 56.

On the side road 60, several service stations, like a restaurant 64 or a hotel 66 are present. These would then accordingly be recommended via the system 10 to the driver as possible next service areas for drowsiness relief, even if the car 54 is still on the expressway 56.

In the case that the driver does either not follow these recommendations or if no such recommendations can be offered by the system 10 in the absence of such service areas, or at least absence of service areas according to the preferences of the driver, the system 10 may provide an alarm, e.g. via alarm unit 28, to the driver that he/she shall use the next service area that is coming up in order to reduce his/her drowsiness. This alarm may for example be provided if the aforementioned drowsiness level D _a i _arm is reached or passed. For this option, the preferences possibly entered by the driver in the system 10 regarding his/her preferences of service areas may be disregarded.

The chart shown in Fig. 5 also illustrates an example of such a process for finding and suggesting service areas by the system 10.

All the steps mentioned before that can be carried out by the processing unit 12 can be realized by a computer program that runs or is carried out on a computer or computer-like device that acts as the processing unit 12. While the invention has been illustrated and described in detail in the drawings and foregoing description, such illustration and description are to be considered illustrative or exemplary and not restrictive; the invention is not limited to the disclosed embodiments. Other variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed invention, from a study of the drawings, the disclosure, and the appended claims.

In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude a plurality. A single element or other unit may fulfill the functions of several items recited in the claims. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.

A computer program may be stored/distributed on a suitable medium, such as an optical storage medium or a solid-state medium supplied together with or as part of other hardware, but may also be distributed in other forms, such as via the Internet or other wired or wireless telecommunication systems.

Any reference signs in the claims should not be construed as limiting the scope.