DE102012001939B4 - Method and apparatus for detecting a mobile device and vehicle left in a vehicle - Google Patents

Abstract

A method for detecting a mobile device (1) left behind in a vehicle (10), a signal (6; 9) being transmitted by radio between the mobile device (1) and a signal transceiver (4), and the received field strength of the the signal (6; 9) received on the mobile device (1) or on the signal transceiver (4) is evaluated by the signal transceiver (4) and depending on a change in the received field strength over time at or immediately after when an occupant exits the vehicle (10), it is detected whether the mobile device (1) has been left in the vehicle (10), the method comprising at least the following steps: - from a first predetermined time (11) a value is cyclically generated di is determined for the received field strength as a function of the current signal (6; 9), the respective cycle being designated by the index i, a maximum value DMaxi of a predetermined number n of the last previously determined values di becomes zy is determined cyclically,- a mean value MDiof a predetermined number m of the maximum values DMaxi determined up to now is determined cyclically,- a difference M1i between the mean value MDiand the maximum value DMaxi determined last respectively last determined,- a value rk is determined cyclically for the Received field strength depending on the current signal (6; 9), where k denotes the respective cycle,- a maximum value RMaxk for the reception field strength of a predetermined number o of the last values rk determined up to now is determined cyclically,- at the first predetermined point in time (11) an average value RM of a predetermined number m of the last previously determined maximum values RMaxk, - from the first predetermined point in time (11) a value di for the received field strength is determined cyclically depending on the current signal (6; 9), the respective cycle being designated by the index i, which starts from the predetermined point in time ( 11) begins.- a maximum value DMaxi of a predetermined number n of the values di last determined so far is determined cyclically, - a difference M2i between the mean value RM and the maximum value DMaxi determined last in each case is determined cyclically, with it being detected that the mobile device (1) is in the vehicle (10) has been forgotten if the difference M1i and the difference M2ibis to exit never e exceeds or falls below a predetermined threshold value.

Description

The present invention relates to a method and a device for detecting a mobile device left in a vehicle. In this case, a signal is transmitted by radio between the mobile device and a signal transceiver. The received field strength of the signal received at the mobile device or at the signal transceiver is evaluated by the signal transceiver. Depending on a change in the received field strength over time when an occupant exits the vehicle, it is detected whether or not the mobile device has been left in the vehicle.

the DE 10 2005 047 711 A1 describes a device for checking the presence of at least one object.

the DE 201 09 121 U1 relates to an alarm device of an in-vehicle mobile phone hands-free device.

the DE 100 23 984 A1 relates to a forget/lose warning device.

the DE 100 47 322 A1 relates to a signal transmitter which is assigned to a base unit, a distance between the signal transmitter and the base unit being determined by a signal exchange between the signal transmitter and the base unit.

The presentation "Position Determination with WLAN and Bluetooth", Andreas Janzen, University of Freiburg 2007, deals with determining the position of devices that are integrated into a network via WLAN and Bluetooth.

the EP 1 467 322 A2 describes a motor vehicle door locking system with a controller and a handset, with a radio link between the controller and the handset being set up using Bluetooth.

the DE 10 2004 008 181 A1 relates to a method for warning of a mobile device left behind in a motor vehicle, an attempt being made by means of Bluetooth to set up a communication link to the mobile device.

the EP 1 726 129 B1 describes a method and a device for adaptively activating or deactivating the coordination of the radio activities of two mobile radio transmitting and/or receiving devices.

the DE 10 2009 038 580 A1 FIG. 1 shows a method and an apparatus for detecting a mobile device left in a vehicle. In this case, a signal is transmitted by radio between the mobile device and a signal transceiver. The received field strength of the signal received at the mobile device or at the signal transceiver is evaluated by the signal transceiver and depending on a change in the received field strength over time when an occupant exits the vehicle, it is determined whether the mobile device is in the vehicle has been abandoned or not.

The object of the present invention is to warn a vehicle occupant, in particular a driver, directly when or immediately after getting out of the vehicle if a cell phone has been forgotten in the vehicle.

According to the invention, this object is achieved by a method for detecting a mobile device left in a vehicle according to claim 1, by a device for detecting a mobile device left in a vehicle according to claim 10 and by a vehicle according to claim 11. The dependent claims define preferred and advantageous embodiments of the present invention.

• - ab einem ersten vorbestimmten Zeitpunkt wird zyklisch ein Wert d_i für die Empfangsfeldstärke abhängig von dem aktuellen Signal bestimmt, wobei durch den Index i der jeweilige Zyklus benannt ist,
• - ein Maximalwert DMax_i einer vorbestimmten Anzahl n der letzten bisher bestimmten Werte d_i wird zyklisch bestimmt,
• - ein Mittelwert MD_i einer vorbestimmten Anzahl m der letzten bisher bestimmten Maximalwerte DMax_i wird zyklisch bestimmt,
• - eine Differenz M1_i zwischen dem Mittelwert MD_i und dem jeweils zuletzt ermittelten Maximalwert DMax_i wird zyklisch bestimmt, und
• - erfasst wird, dass das Mobilgerät in dem Fahrzeug vergessen worden ist, wenn die Differenz M1_i bis zum Aussteigen niemals einen vorbestimmten Schwellenwert über- bzw. unterschreitet,
• - ab einem zweiten vorbestimmten Zeitpunkt (11a) wird zyklisch ein Wert r_k für die Empfangsfeldstärke abhängig von dem aktuellen Signal (6; 9) bestimmt, wobei durch k der jeweilige Zyklus benannt ist,
• - ein Maximalwert RMax_k für die Empfangsfeldstärke einer vorbestimmten Anzahl o der letzten bisher bestimmten Werte r_k wird zyklisch bestimmt,
• - zum ersten vorbestimmten Zeitpunkt (11) wird ein Mittelwert RM einer vorbestimmten Anzahl m der letzten bisher bestimmten Maximalwerte RMax_k bestimmt,
• - ab dem ersten vorbestimmten Zeitpunkt (11) wird zyklisch ein Wert d_i für die Empfangsfeldstärke abhängig von dem aktuellen Signal (6; 9) bestimmt, wobei durch den Index i der jeweilige Zyklus benannt ist, der ab dem vorbestimmten Zeitpunkt (11) beginnt.
• - ein Maximalwert DMax_i einer vorbestimmten Anzahl n der letzten bisher bestimmten Werte d_i wird zyklisch bestimmt,
• - eine Differenz M2_i zwischen dem Mittelwert RM und dem jeweils zuletzt ermittelten Maximalwert DMax_i wird zyklisch bestimmt,

wobei erfasst wird, dass das Mobilgerät in dem Fahrzeug vergessen worden ist, wenn die Differenz M1_i und die Differenz M2_i bis zum Aussteigen niemals einen vorbestimmten Schwellenwert über- bzw. unterschreitet.Within the scope of the present invention, an inventive method is provided for detecting a mobile device left in a vehicle, in particular a mobile phone. A signal is transmitted wirelessly between the mobile device and a signal transceiver, with the received field strength of the signal received by the signal transceiver or by the mobile device being detected and evaluated by the signal transceiver. Depending on a change in this reception field strength over time, it is determined at the time an occupant exits the vehicle whether a mobile device has been left behind in the vehicle. The procedure includes the following steps:

• - From a first predetermined point in time, a value d _i for the reception field strength is determined cyclically depending on the current signal, the respective cycle being designated by the index i,
• - a maximum value DMax _{i of} a predetermined number n of the last previously determined values d _i is determined cyclically,
• - a mean value MD _{i of} a predetermined number m of the last maximum values DMax _i determined so far is determined cyclically,
• - a difference M1 _i between the mean value MD _i and the maximum value DMax _i last determined in each case is determined cyclically, and
• - it is detected that the mobile device has been forgotten in the vehicle if the difference M1 _i never exceeds or falls below a predetermined threshold value before getting out,
• - From a second predetermined point in time (11a), a value r _k for the reception field strength is determined cyclically as a function of the current signal (6; 9), with k denoting the respective cycle,
• - a maximum value RMax _k for the reception field strength of a predetermined number o of the last previously determined values r _k is determined cyclically,
• - at the first predetermined point in time (11), a mean value RM of a predetermined number m of the last maximum values RMax _k determined up to this point is determined,
• - From the first predetermined point in time (11), a value d _i for the received field strength is determined cyclically depending on the current signal (6; 9), the index i designating the respective cycle that begins from the predetermined point in time (11). .
• - a maximum value DMax _{i of} a predetermined number n of the last previously determined values d _i is determined cyclically,
• - a difference M2 _i between the mean value RM and the last determined maximum value DMax _i is determined cyclically,

wherein it is detected that the mobile device has been forgotten in the vehicle if the difference M1 _i and the difference M2 _i until getting out never exceeds or falls below a predetermined threshold value.

According to the invention, a cycle is repeated after a predetermined period of time. The time period should be chosen so that several cycles are run through from the predetermined time period until disembarking. The time period can be 125 ms, for example.

The inventively predetermined number n of the last previously determined values for determining the maximum value DMax _i is adapted to the period of the cycle. A number n=10 has proven to be advantageous for a cycle time of 125 ms.

The inventive predetermined number m of the last previously determined maximum values DMax _i for determining the mean value MD _i is also adapted to the period of the cycle and to the number n. m=10 has also proven to be advantageous for the number m.

A one-off disturbance of the signal is compensated for by the averaging according to the invention if enough cycles are taken into account.

The inventive predetermined number m of the last previously determined maximum values DMax _i for determining the mean value M1 _i is also adapted to the period of the cycle and to the number n. m=10 has also proven to be advantageous for the number m.

The number of values r _k predetermined according to the invention or the last previously determined values for determining the maximum value RMax _k is adapted to the period of the cycle. A number n=10 has proven to be advantageous for a cycle time of 125 ms.

According to the invention, the values d _i and r _k , the maximum values DMax _i and RMax _k , the mean values MD _i and RM and the difference M1 _i and M2 _i are stored in a memory so that they can be called up for the next cycles.

According to the invention, the difference M1 _i can be determined both by subtracting the mean value MD _i from the maximum value DMax _i determined last in each case and by subtracting the maximum value DMax _i determined last in each case from the mean value MD _i , since the sign of the difference M1 _i is irrelevant.

According to the invention, the difference M2 _i can be determined both by subtracting the mean value RM from the maximum value DMax _i determined last in each case and by subtracting the maximum value DMax _i determined last in each case from the mean value RM, since the sign of the difference M1 _i is irrelevant.

• - bei einem positiven Vorzeichen der Differenz M1_i bzw. M2_i bis zum Aussteigen niemals ein Schwellenwert überschritten wird

oder

• - bei einem negativen Vorzeichen der Differenz M1_i bzw. M2_i bis zum Aussteigen niemals ein Schwellenwert unterschritten wird.

According to the invention it is detected that the mobile device has been forgotten in the vehicle when

• - If the sign of the difference M1 _i or M2 _i is positive, a threshold value is never exceeded before exiting

or

• - If the sign of the difference M1 _i or M2 _i is negative, a threshold value is never undershot before getting out.

If the sign of the difference M1 _i or M2 _i is positive, the threshold value also has a positive sign tive value. If the difference M1 _i or M2 _i has a negative sign, the threshold value also has a negative value.

In a development of the invention, the absolute value of the difference M1 _i or M2 _i is formed, so that the comparison is always carried out with a positive threshold value.

In the invention, the method recognizes that the mobile device has been left in the vehicle if the difference M1 _i and the difference M2 _i never falls below or exceeds a predetermined threshold value until the vehicle gets out.

In a further development of the invention, if the method according to the invention has detected that a switched-on mobile device has been left in the vehicle, visual and/or acoustic warnings (e.g. via a horn of the vehicle and/or lighting devices or display devices of the vehicle) are given when the occupant exits ) may be issued to inform the occupant or occupants that a mobile device has been left in the vehicle.

The method according to the invention comprises two cases. In the first case, the mobile device sends a signal to the signal transceiver, which receives this signal and determines a reception field strength of the signal. In the second case, the signal transceiver sends a signal to the mobile device, which determines the reception field strength of the signal and transmits a value of this determined reception field strength by means of a further signal to the signal transceiver. In both cases, the signal transceiver acquires values of the received field strength.

If a switched-on mobile device is left in the vehicle, it remains in the same place even while an occupant exits the vehicle, so that the received field strength of the signal, which is emitted from the mobile device to the signal transceiver, remains essentially constant , since the distance between the mobile device and the signal transceiver, which significantly affects the reception field strength of the signal, remains constant (provided that the signal transceiver is stationary). On the other hand, the receiving field strength changes when the occupant who gets out of the vehicle carries the mobile device with him, since this changes the distance between the mobile device and the signal transceiver. In other words, by carrying out measurements of the signal strength or reception field strength, it is determined whether the mobile device is moving or whether the mobile device is changing its position.

In a preferred embodiment according to the invention, the signal is only examined for changes in terms of the received field strength from a predetermined first point in time before the occupant gets out of the vehicle. The predetermined point in time can be present when an engine of the vehicle is switched off or when an ignition key of the vehicle is removed.

According to the invention, it is not necessary to examine changes in the received field strength all the time. Instead, it is sufficient to examine or evaluate the received field strength with regard to changes only shortly before the last occupant or the driver, who in most cases is the last occupant, gets out of the vehicle. It is a good indication that all occupants will soon exit the vehicle when the vehicle's engine is switched off or when the ignition key is removed.

As a development, the second predetermined point in time can be before the first predetermined point in time. A possible indication of a point in time shortly before the first predetermined point in time is when the speed of the vehicle falls below a predetermined value. From this second point in time, the values r _k are determined. If the speed of the vehicle again exceeds the predetermined value, the method can be ended again since it can no longer be assumed that the vehicle will be left. If the speed of the vehicle falls below the predetermined value again, the second predetermined point in time is thus set again to this point in time. Other indications are also conceivable which make it likely that a driver has arrived, such as reaching a predetermined destination which is stored in a navigation device.

In this case, in particular from the predetermined first point in time, a Bluetooth connection is subsequently maintained or set up without an associated Bluetooth service to the mobile device. With such a Bluetooth connection (without Bluetooth service), the Bluetooth-enabled mobile device can send an RSSI signal (RSSI "Receive Signal Strength Indicator"), which is defined in the Bluetooth standard, to the signal transceiver, to transmit to the signal transceiver a signal strength or reception field strength of the signal transmitted by the signal transceiver and received by the mobile device.

In other words, the mobile device receives a signal from the signal transceiver, determines the reception field strength of this received signal and transmits a value of this reception field strength determined in this way to the signal transceiver using an RSSI signal. Based on this received field strength transmitted from the mobile device to the signal transceiver, the method according to the invention can now decide whether the mobile device has been left in the vehicle or not.

The proposed Bluetooth connection without an associated Bluetooth service has the advantage that as a result, for example, no incoming telephone connections are accepted by an infotainment system in the vehicle, which could be perceived as annoying when getting out.

Furthermore, the invention is not limited to a Bluetooth connection, but includes any type of radio connection that makes it possible to establish a connection with the vehicle.

In one development of the method according to the invention, the exit of the occupant is detected when an opening of a driver's door of the vehicle is detected, a seat occupancy detector detects a seat that has become free, or when the vehicle is locked.

The mobile device according to the invention can be a mobile phone, but also other devices that can be coupled using a Bluetooth connection, such as navigation devices, media players, small computers.

• - ab einem ersten vorbestimmten Zeitpunkt (11) wird zyklisch ein Wert d_i für die Empfangsfeldstärke abhängig von dem aktuellen Signal (6; 9) bestimmt, wobei durch den Index i der jeweilige Zyklus benannt ist,
• - ein Maximalwert DMax_i einer vorbestimmten Anzahl n der letzten bisher bestimmten Werte d_i wird zyklisch bestimmt,
• - ein Mittelwert MD_i einer vorbestimmten Anzahl m der letzten bisher bestimmten Maximalwerte DMax_i wird zyklisch bestimmt,
• - eine Differenz M1_i zwischen dem Mittelwert MD_i und dem jeweils zuletzt ermittelten Maximalwert DMax_i wird zyklisch bestimmt,
• - ab einem zweiten vorbestimmten Zeitpunkt (11a) wird zyklisch ein Wert r_k für die Empfangsfeldstärke abhängig von dem aktuellen Signal (6; 9) bestimmt, wobei durch k der jeweilige Zyklus benannt ist,
• - ein Maximalwert RMax_k für die Empfangsfeldstärke einer vorbestimmten Anzahl o der letzten bisher bestimmten Werte r_k wird zyklisch bestimmt,
• - zum ersten vorbestimmten Zeitpunkt (11) wird ein Mittelwert RM einer vorbestimmten Anzahl m der letzten bisher bestimmten Maximalwerte RMax_k bestimmt,
• - ab dem ersten vorbestimmten Zeitpunkt (11) wird zyklisch ein Wert d_i für die Empfangsfeldstärke abhängig von dem aktuellen Signal (6; 9) bestimmt, wobei durch den Index i der jeweilige Zyklus benannt ist, der ab dem vorbestimmten Zeitpunkt (11) beginnt.
• - ein Maximalwert DMax_i einer vorbestimmten Anzahl n der letzten bisher bestimmten Werte d_i wird zyklisch bestimmt,
• - eine Differenz M2_i zwischen dem Mittelwert RM und dem jeweils zuletzt ermittelten Maximalwert DMax_i wird zyklisch bestimmt,

wobei erfasst wird, dass das Mobilgerät in dem Fahrzeug vergessen worden ist, wenn die Differenz M1_i und die Differenz M2_i bis zum Aussteigen niemals einen vorbestimmten Schwellenwert über- bzw. unterschreitetAn apparatus for detecting a mobile device left in a vehicle is also provided within the scope of the present invention. The device includes a signal transceiver, evaluation means and output means. Signals are sent wirelessly to the mobile device and signals are received wirelessly from the mobile device by means of the signal transceiver. The evaluation means evaluate a received signal strength of the signal received by the signal transceiver or by the mobile device and, depending on a time profile or a change over time in this received signal strength when an occupant exits the vehicle, decides whether the mobile device is in the vehicle has been left or not. Finally, the output means are designed to output an information signal or a warning if the evaluation means have decided that the mobile device was left behind in the vehicle when it got out. The evaluation means is designed to carry out the following steps:

• - From a first predetermined point in time (11), a value d _i for the reception field strength is determined cyclically as a function of the current signal (6; 9), the respective cycle being designated by the index i,
• - a maximum value DMax _{i of} a predetermined number n of the last previously determined values d _i is determined cyclically,
• - a mean value MD _{i of} a predetermined number m of the last maximum values DMax _i determined so far is determined cyclically,
• - a difference M1 _i between the mean value MD _i and the maximum value DMax _i last determined in each case is determined cyclically,
• - From a second predetermined point in time (11a), a value r _k for the reception field strength is determined cyclically as a function of the current signal (6; 9), with k denoting the respective cycle,
• - a maximum value RMax _k for the reception field strength of a predetermined number o of the last previously determined values r _k is determined cyclically,
• - at the first predetermined point in time (11), a mean value RM of a predetermined number m of the last maximum values RMax _k determined up to this point is determined,
• - From the first predetermined point in time (11), a value d _i for the received field strength is determined cyclically depending on the current signal (6; 9), the index i designating the respective cycle that begins from the predetermined point in time (11). .
• - a maximum value DMax _{i of} a predetermined number n of the last previously determined values d _i is determined cyclically,
• - a difference M2 _i between the mean value RM and the last determined maximum value DMax _i is determined cyclically,

wherein it is detected that the mobile device has been forgotten in the vehicle if the difference M1 _i and the difference M2 _i until getting out never exceeds or falls below a predetermined threshold value

In the case of the device according to the invention, two cases must be distinguished. In the first case, the mobile device sends a signal to the signal transceiver, which then determines a received signal strength of this received signal and feeds it to the evaluation means. In the second case, the signal transceiver sends in Signal to the mobile device, which then determines a received signal strength of this received signal. The mobile device then sends a value of this received signal strength, for example by means of an RSSI signal (if the mobile device is Bluetooth-enabled) to the signal transceiver, which forwards the received signal strength transmitted in this way to the evaluation means.

The advantage of the present invention also lies in the fact that only one infotainment system of the vehicle has to be modified. Commercial mobile phones can be used according to the invention unchanged, i.e. without hardware or software changes. In addition, a user does not need another device to be notified of the abandoned mobile device. It is also advantageous that the user is warned directly when leaving the vehicle. At this point, he is in close proximity to the vehicle and thus in close proximity to any mobile device that may have been left behind.

The present invention is particularly useful for detecting a powered-on mobile device left in a motor vehicle. However, the present invention is not limited to this preferred area of application, since the principle of the present invention also enables the detection of abandoned mobile devices in any environment (e.g. in a house). In principle, the present invention also makes it possible, for example, if a person leaves a specific room, to issue a warning about a switched-on mobile device left in the room. In addition, the present invention can of course also be applied to aircraft, ships and rail-bound vehicles.

• 1 stellt schematisch ein erfindungsgemäßes Fahrzeug mit einer erfindungsgemäßen Vorrichtung dar.
• In 2 ist ein Verlauf einer Empfangsfeldstärke über der Zeit dargestellt, mit welchem erfasst wird, ob ein Mobilgerät in einem Fahrzeug zurückgelassen worden ist.

The present invention is explained in detail below on the basis of preferred embodiments according to the invention with reference to the figures.

• 1 shows schematically a vehicle according to the invention with a device according to the invention.
• In 2 shows a course of a reception field strength over time, with which it is detected whether a mobile device has been left in a vehicle.

In 1 a vehicle 10 according to the invention is shown which, in addition to a driver's door 7 , comprises a device 5 according to the invention for detecting a mobile phone 1 left behind in the vehicle 10 . The device 5 in turn comprises optical and/or acoustic output means 2, evaluation means 3 and a Bluetooth-enabled signal transceiver 4.

The present invention will now be described below by way of example with reference to FIG 1 explained in detail.

A driver of the vehicle 10 enters the vehicle 10 with his mobile phone 1 and establishes a Bluetooth connection between his mobile phone 1 and the Bluetooth signal transceiver 4, which could belong to an infotainment system (not shown) of the vehicle, for example . (The Bluetooth connection could also be set up automatically.) After the driver has finished driving the vehicle 10, he turns off the engine of the vehicle 10 (terminal 15 off) and/or removes an ignition key from the vehicle 10, whereby the mobile phone 1 remains connected to the signal transceiver 4. The evaluation means 3 detect that the engine has been switched off or that the ignition key has been removed, and signal the signal transceiver 4 to store a current value (RSSI value) of a received field strength. This received field strength corresponds to a received field strength determined by mobile phone 1, which was determined for a signal 6 transmitted by signal transceiver 4 and received by mobile phone 1 and in the form of an RSSI value within a range of the signal 9 sent to the mobile phone 1 to the signal transceiver 4 has been transmitted. In order to compensate for a measurement inaccuracy in a (single) RSSI measurement value, several RSSI values transmitted by the mobile phone 1 are averaged to determine the RSSI value to be stored. Furthermore, the signal transceiver 4 continues to continuously measure the current RSSI value transmitted by the mobile phone 1 . If the evaluation means 3 detect that the mobile device 1 has been forgotten in the vehicle 10, a flag is set within the evaluation means 3.

If evaluation means 3 subsequently detect (after switching off the engine or removing the ignition key) opening of driver's door 7, this flag is evaluated. If the flag is not set, the evaluation means 3 assume that the driver has left his mobile phone 1 inside the vehicle 10 and activate the output means 2, which inform the driver by means of acoustic and/or visual signals (for example via a message on a screen of the vehicle). Infotainment system) inform that there is still a switched-on mobile phone 1 inside the vehicle 10.

In 2 is a time course 8 of RSSI values shown in dB, which comes from a mobile phone 1, which when getting out of the Vehicle 10 is taken along by the driver. Times in s are plotted on the x-axis and RSSI values in dB are plotted on the y-axis. At a point in time 11a the speed of the vehicle 10 falls below the predetermined threshold, approximately at a first point in time 11 the driver removes the ignition key and puts his cell phone 1 in a jacket pocket. The driver then opens the driver's door 7 at the third point in time 12. Between the second point in time 11a and the first point in time 11 and between the first point in time 11 and the third point in time 12, the device 5 continuously records the current RSSI values and maximum values transmitted by the mobile phone 1 a predetermined number of the last previously determined RSSI values r _k or d _i are determined.
The mean value RM is determined at the first point in time 11 . A difference M2 _i between the mean value RM and the maximum value DMax _i last determined in each case is then determined cyclically up to the third point in time 12 . In addition, the mean value MD _i is continuously determined from the first point in time 11 and a difference M1 _i is determined between the mean value MD _i and the maximum value DMax _i determined last in each case. As soon as the difference M1 _i or M2 _i has exceeded or fallen below a predetermined threshold value, a flag is set.
It can be seen that a difference between the RSSI value at the first point in time 11 and, for example, an RSSI value at a fourth point in time 13 is more than 20 dB. Due to the averaging, the very strong deviation in the case of individual disturbances is reduced. If the predetermined threshold value is set to 10 dB, for example, the above-mentioned flag is set at the latest at the third point in time 13, which signals when the driver's door is opened at the third point in time 12 that the driver has not forgotten the cell phone 1 in the vehicle 10 .

Reference List

1

mobile phone

2

output means

3

evaluation means

4

bluetooth transceiver

5

contraption

6

signal

7

Drivers door

8th

History of RSSI values over time

9

signal

10

vehicle

11

first time

11a

second point in time

12

third point in time

13

fourth point in time

Claims (11)

A method for detecting a mobile device (1) left behind in a vehicle (10), a signal (6; 9) being transmitted by radio between the mobile device (1) and a signal transceiver (4), and the received field strength of the signal (6; 9) received on the mobile device (1) or on the signal transceiver (4) is evaluated by the signal transceiver (4) and depending on a change in the received field strength over time at or immediately after an occupant has left the vehicle (10), it is detected whether the mobile device (1) has been left in the vehicle (10), the method comprising at least the following steps: - from a first predetermined point in time (11), a value d _i for the received field strength as a function of the current signal (6; 9), the respective cycle being designated by the index i, - a maximum value DMax _{i of} a predetermined number n of the last previously determined values d _i is determined cyclically, - a mean value MD _i of a predetermined number m of the last previously determined maximum values DMax _i is determined cyclically, - a difference M1 _i between the mean value MD _i and the maximum value DMax _i last determined in each case is determined cyclically, - from a second predetermined time (11a), a value r _k for the reception field strength is cyclically dependent on the current signal (6; 9), where k designates the respective cycle, - a maximum value RMax _k for the received field strength of a predetermined number o of the last values r _k determined up to now is determined cyclically, - at the first predetermined point in time (11), an average value RM of a predetermined number m of the last maximum values RMax _k determined so far, - from the first predetermined point in time (11), a value d _i for the reception field strength is determined cyclically depending on the current signal (6; 9), the respective cycle being named by the index i which starts from the predetermined time (11). - a maximum value DMax _i of a predetermined number n of the last previously determined values d _i is determined cyclically, - a difference M2 _i between the mean value RM and the maximum value DMax _i last determined in each case is determined cyclically, with it being recorded that the mobile device (1st ) has been forgotten in the vehicle (10) when the difference M1 _i and the Difference M2 _i never exceeds or falls below a predetermined threshold value until getting out. procedure after claim 1 wherein the predetermined time (11) is when an engine of the vehicle (10) is turned off or when an ignition key of the vehicle (10) is removed. Method according to one of the preceding claims, in which the second predetermined point in time (11a) is before the first predetermined point in time (11). Method according to one of the preceding claims, wherein the second predetermined point in time (11a) is present when a speed of the vehicle (10) falls below a predetermined value. Method according to one of the preceding claims, wherein after the predetermined point in time (11) a Bluetooth connection is maintained in follow-up without an associated Bluetooth service to the mobile device (1). Method according to one of the preceding claims, characterized in that the mobile device (1) detects the received field strength of the signal (6) received on the Bluetooth-enabled mobile device (1) in the form of a further signal (9) which is an RSSI signal from the mobile device ( 1) is, emits. Method according to one of the preceding claims, characterized in that the exit of the occupant is detected when an opening of a driver's door (7) of the vehicle (10) is detected, a seat occupancy detector detects a seat becoming free or when the vehicle (10) is locked . Method according to one of the preceding claims, characterized in that a visual and/or acoustic warning is output if the forgotten mobile device (1) is detected when the occupant gets out. Method according to one of the preceding claims, characterized in that the mobile device (1) is a mobile phone. Device for detecting a mobile device (1) left behind in a vehicle (10), characterized by a signal transceiver (4) which is used to transmit a signal (6) to the mobile device (1) and to receive a signal ( 9) configured by the mobile device (1) via radio, evaluation means (3) for evaluating the received signal strength of the signal (6; 9) received by the signal transceiver (4) or by the mobile device (1) depending on to detect from a change in the received signal strength over time when or immediately after an occupant leaves the vehicle (10) whether the mobile device (1) has been left in the vehicle (10), output means (2) for outputting an information signal if the Evaluation means (3) have detected that the mobile device (1) has been left in the vehicle (10) and wherein the evaluation means (3) is designed to carry out the following steps, - from a first predetermined point in time (11) wi rd cyclically a value d _i for the received field strength depending on the current signal (6; 9), with the respective cycle being designated by the index i, - a maximum value DMax _{i of} a predetermined number n of the last values d _i determined up to now is determined cyclically, - a mean value MD _{i of} a predetermined number m of the last maximum values DMax determined up to now _i is determined cyclically, - a difference M1 _i between the mean value MD _i and the maximum value DMax _i determined last is determined cyclically, and - from a second predetermined point in time (11a), a value r _k for the received field strength is determined cyclically as a function of the current signal (6; 9), where k designates the respective cycle, - a maximum value RMax _k for the received field strength of a predetermined number o of the last previously determined values r _k is determined cyclically, - at the first predetermined point in time (11), a Mean value RM of a predetermined number m of the last maximum values RMax _k determined up to this point is determined - from the first predetermined time (11) z cyclically a value d _i for the reception field strength depending on the current signal (6; 9), the index i designating the respective cycle which begins at the predetermined point in time (11). - a maximum value DMax _i of a predetermined number n of the last previously determined values d _i is determined cyclically, - a difference M2 _i between the mean value RM and the maximum value DMax _i last determined in each case is determined cyclically, and it is detected that the mobile device ( 1) has been forgotten in the vehicle (10) if the difference M1 _i and the difference M2 _i never exceeds or falls below a predetermined threshold value before exiting. Vehicle with a device (5). claim 10 .

Images