DE102018109659B4 - Distance control between two vehicles - Google Patents

Abstract

Method for checking the distance between two vehicles (12) with the following steps: sending out first ultrasonic signals (34) from a first vehicle (12), receiving the first ultrasonic signals (34) sent out from the first vehicle (12) with a second vehicle (12) ,Emission of a second ultrasonic signal (36) from the second vehicle (12) with a predetermined delay to each received first ultrasonic signal (34),Receiving the second ultrasonic signals (36) emitted by the second vehicle (12) with the first vehicle (12 ), determining a time difference between the transmission of the first ultrasonic signal (34) and the receipt of the second ultrasonic signal (36) by the first vehicle (12), and determining a distance (32) between the first and second vehicle (12) based on the time difference minus the deceleration by the first vehicle (12), characterized in that the method comprises an additional step of transmitting the distance (32) between the first and second vehicles (12) from the first vehicle (12) to the second vehicle (12) via a communication link (40).

Description

The present invention relates to a method for checking the distance between two vehicles, in particular for driving in a convoy.

The present invention also relates to a platoon of vehicles with a plurality of vehicles, the vehicles of the platoon of vehicles being designed to carry out the above method.

In principle, the motorcade can comprise any number of vehicles, which can be designed differently. The vehicles are preferably trucks. The vehicles drive in a line of vehicles at a distance of seven to twelve meters, for example, to reduce air resistance and thus fuel consumption. The convoy of vehicles typically travels at a speed of about 80 km/h, which is a typical speed for trucks. This means that the usual safety distances when driving in a convoy can sometimes be significantly undercut. In principle, driving in a convoy of vehicles can be carried out on any roads. However, convoys of vehicles preferably drive on freeways or similar roads which, for example, have separate lanes for each direction of travel and therefore require little interaction with other road users.

A first vehicle of the platoon takes the lead of the platoon, and the following vehicles drive in a manner adapted to the leading vehicle. The following vehicles are preferably designed to automatically follow the vehicle in front. Thus, only the driver of a vehicle leading the vehicle convoy has to actively guide his vehicle or monitor the guidance by an autonomous control system. Vehicle drivers of the following vehicles can carry out activities that are independent of driving the vehicle, for example administrative activities, while driving in the vehicle convoy. Driving in the vehicle convoy is therefore carried out autonomously, at least in the following vehicles, by a driving support system, it being possible for communication with other vehicles in the convoy to take place.

When driving in a convoy of vehicles, it is necessary for the vehicles in the convoy to keep safe distances between the individual vehicles, for example. Accordingly, objects in front of the respective vehicle must be detected. Existing vehicle support systems typically use LiDAR-based sensors, in particular laser scanners, radar sensors, and/or optical cameras, to capture an environment of the vehicle and to detect and track objects in the environment. This is very complex and associated with high costs. Due to the distances between the vehicles of seven to twelve meters, conventional, inexpensive ultrasonic sensors that emit an ultrasonic pulse and receive echoes from it, and which are widely used in the automotive industry, cannot be used. Their range is typically less than the usual distances between the vehicles in the vehicle convoy.

In this context, from the DE 10 2015 211 117 A1 a convoy driving control system for a convoy with a leading vehicle and at least one following vehicle that automatically follows the leading vehicle. Each of the vehicles in the platoon includes a vehicle-to-vehicle communication device that is set up to send at least one vehicle parameter of the vehicle to a following vehicle and to receive the vehicle parameter of a vehicle driving ahead. Furthermore, each of the vehicles in the platoon comprises a vehicle-to-vehicle control device which is set up to control the vehicle parameter of the vehicle based on the received at least one vehicle parameter of the vehicle driving ahead.

Furthermore, from the DE 10 2015 213 888 B4 a control device of a vehicle is known. The control device includes an interface that is set up to communicate with an ultrasonic transceiver of the vehicle, and at least one processor that is set up to receive a signal detected by the ultrasonic transceiver via the interface. The processor is further configured to demodulate the signal to obtain packetized data, wherein the packetized data includes a driving parameter of a neighboring vehicle. The processor is also set up to trigger a driver assistance function based on the driving parameter.

The DE 10 2016 110 001 A1 relates to a system for data transmission and for determining and/or adjusting the distance between vehicles. The system uses data transmission signals to determine the distance between at least two vehicles.

From the EP 1 788 749 B1 a method and a device for vehicle-to-vehicle multi-hop broadcast communication are known. The method for ad hoc network communication includes determining position data of a receiving vehicle, the position data of the receiving vehicle include a position, a speed, and a direction of the receiving vehicle. The method further includes receiving position data from transmitting vehicles, the position data of a transmitting vehicle including a position, speed and direction of the transmitting vehicle. The method further includes calculating a relative position, a relative speed, and a relative direction between the receiving vehicle and the transmitting vehicle, and calculating a density of vehicles from the calculated relative positions. In addition, the method includes periodically transmitting the position data of the receiving vehicle, wherein a time for periodically transmitting the position data of the receiving vehicle is adjusted in accordance with the density of the vehicles.

The U.S. 6,965,829 B2 provides an on-vehicle electronic device including a wireless communication unit that performs wireless communication via a wireless LAN, and means for acquiring position information and speed information of vehicles in front of and behind the own vehicle using the wireless communication unit. The apparatus further includes means for calculating the inter-vehicle distances between the subject vehicle and the vehicles before and after the subject vehicle by referring to map information based on the acquired position information and speed information, and means for performing a collision avoidance measure when a calculated inter-vehicle distance is equal to or smaller than a predetermined one distance and the speeds of the own vehicle and the vehicles in front of and behind the own vehicle are equal to or higher than a predetermined speed.

From the DE 10 2012 222 334 A1 a method for determining the relative distance and the relative movement of several road users based on acoustic signals is known.

From the JP 2000 - 266 849 A a distance determination system is known in which ultrasonic signals are exchanged via ultrasonic sensors between vehicles driving behind one another.

Proceeding from the prior art mentioned above, the invention is therefore based on the object of specifying a method for checking the distance between two vehicles and a vehicle convoy with a plurality of vehicles, which enable reliable and cost-effective distance control between two vehicles, particularly when driving in a convoy.

The object is achieved according to the invention by the features of the independent claims. Advantageous refinements of the invention are specified in the dependent claims.

According to the invention, a method for checking the distance between two vehicles is thus specified, in particular for driving in a convoy, with the following steps: sending out first ultrasonic signals from a first vehicle, receiving the first ultrasonic signals sent out by the first vehicle with a second vehicle, sending out from a second ultrasonic signal from the second vehicle with a predetermined delay to each received first ultrasonic signal, receiving the second ultrasonic signals emitted by the second vehicle with the first vehicle, determining a time difference between the emission of the first ultrasonic signal and the reception of the second ultrasonic signal by the first vehicle, and determining a distance between the first and second vehicles based on the time difference minus the deceleration by the first vehicle.

According to the invention, a platoon of vehicles with a plurality of vehicles is also specified, the vehicles of the platoon of vehicles being designed to carry out the above method.

The basic idea of the present invention is therefore to detect a distance between two vehicles using ultrasonic signals. The transmission of the first ultrasonic signal from the first vehicle to the second vehicle and the transmission of the second ultrasonic signal from the second vehicle to the first vehicle make it possible to use conventional ultrasonic sensors. A typical area of application for ultrasonic sensors for monitoring a maximum distance range of typically five to seven meters can be expanded by the second vehicle sending back the second ultrasonic signal based on the first ultrasonic signal in a time-defined manner with a known delay. It is thus possible to use the ultrasonic sensors for distances of typically ten to twelve meters or more, as a result of which the method can be carried out reliably with conventional ultrasonic sensors, in particular in a convoy of vehicles with small distances between the vehicles. Only ultrasonic sensors that are known per se and are available at low cost are used, so that the distances between the vehicles can be monitored at low cost. This applies in particular to driving in a convoy of vehicles, in which shorter safety distances can be used than in individual traffic, which can be covered with the extended range of the ultrasonic sensors. The method can also be carried out using ultrasonic sensors known per se, which are common in parking assistance systems, for example, and are therefore available at low cost. The distance control can therefore be carried out in a vehicle with such a parking assistance system without additional hardware being required in the form of further ultrasonic sensors. When driving, the parking assistance system is typically not active, so that the parking assistance system is not restricted in its function. In the case of vehicles that are already equipped with corresponding ultrasonic sensors, the method can thus be carried out cost-effectively by additionally using the already existing ultrasonic sensors for distance control when driving in the vehicle convoy.

In order to avoid mixing different ultrasonic signals emitted by the first vehicle, it is preferred that exactly one first ultrasonic sensor of the first vehicle emits the first ultrasonic signals. Additional first ultrasonic sensors of the first vehicle are preferably deactivated or passive in order to avoid interference when the second vehicle receives the ultrasonic signals emitted by the first ultrasonic sensor. The passive ultrasonic sensor itself does not emit any ultrasonic signals, but can, for example, receive ultrasonic signals including reflections of emitted ultrasonic signals. The same applies to the transmission of the second ultrasonic signals from the second vehicle.

In order to be able to carry out the method universally with different vehicles, it is necessary for the delay in the transmission of the second ultrasonic signal after the reception of the first ultrasonic signal to be known. Correspondingly, the deceleration can be predefined globally for all vehicles. Alternatively, the delay in forming the vehicle convoy can be specified individually in each case, either by a setting by a vehicle driver or by a setting through communication between the individual vehicles in the vehicle convoy. In principle, it is also possible for the second ultrasonic signal to contain coded information that specifies the delay. The first vehicle can therefore decode the delay when receiving the second ultrasonic signal from the second ultrasonic signal and take it into account to determine the distance. The process can thus be carried out very flexibly and without a specific configuration of the vehicles in the column.

The distance control procedure is given here for two vehicles. However, the method can easily be extended to a plurality of vehicles in order to be able to form a correspondingly larger vehicle convoy. Each vehicle, apart from the leading and the last vehicle, is at the same time the first and second vehicle in relation to the respective following vehicle or the preceding vehicle. Only the leading vehicle and the last vehicle in the convoy only play a role as the first or second vehicle.

In principle, the convoy of vehicles can comprise any number of vehicles that are designed in different ways. The vehicles are preferably trucks, which drive behind one another at a distance of, for example, seven to twelve meters in order to reduce air resistance and thus to reduce fuel consumption. At least all vehicles following a vehicle leading the vehicle convoy include a driving support system which controls driving in the vehicle convoy. The driving support system is designed accordingly to monitor the distance between the first and second vehicles, in particular if the distance between the two vehicles falls below a minimum. Driving in the vehicle convoy is therefore carried out autonomously, at least in the following vehicles, by a driving support system, it being possible for communication with other vehicles in the convoy to take place.

Time intervals between the first ultrasonic signals can be selected, for example, as a function of a signal duration of the respectively transmitted ultrasonic signals and/or a range to be achieved and/or taking into account typical delays. In principle, it is possible for a number of first ultrasonic signals to be emitted before a second ultrasonic signal is received. In order to distinguish which first ultrasonic signal a received second ultrasonic signal belongs to, associated first and second ultrasonic signals can be designed in the same way or contain the same identification. Consecutive first ultrasonic signals can be configured differently in pairs or also in groups of a plurality of first ultrasonic signals or contain a different identification. In principle, the transmission of the first or second ultrasonic signals is independent of the reception of the ultrasonic signals, in particular when using a plurality of ultrasonic sensors on the first or second vehicle. Sending and receiving can also take place simultaneously.

When receiving the first ultrasonic signals emitted by the first vehicle as well as when receiving the second ultrasonic signals emitted by the second vehicle, the beginning of the respective ultrasonic signal must be taken into account as a so-called trigger, for example, in order to determine the distance between the two vehicles as a function thereof. Particularly in the case of an ultrasonic signal with a digital modulation, the modulation can also be used for synchronization and determination of the reception time interval. In this case, for example, digital modulation with typically steep edges can be used to carry out an exact time determination on such an edge, alternatively in a combination on a plurality of edges. Analog signals, on the other hand, usually have less steep edges and therefore only allow a lower level of accuracy when determining the reception time interval.

The vehicles of the platoon collectively perform the above procedure. Depending on their position, different vehicles can take on different roles at the same time or one after the other.

In principle, the first vehicle can comprise an ultrasonic sensor for emitting the first ultrasonic signals, which also receives the second ultrasonic signal emitted by the second vehicle. Alternatively, the first vehicle can include one or more additional ultrasonic sensors, which receive or receive the second ultrasonic signal emitted by the second vehicle. In this case, an ultrasonic sensor can only transmit the first ultrasonic signals.

In principle, the second vehicle can comprise an ultrasonic sensor for receiving the first ultrasonic signals from the first vehicle, which also emits the second ultrasonic signal. Alternatively, the second vehicle can include one or more additional ultrasonic sensors, which receive or receive the first ultrasonic signal emitted by the first vehicle. In this case, an ultrasonic sensor can only transmit the second ultrasonic signals.

The distance between the first and second vehicle can be compared to a predetermined distance for distance control in order to determine deviations. In particular, it is possible to monitor whether the distance between the two vehicles falls below a minimum distance. A change in the distance can also be dynamically determined for distance control based on distance determinations that follow one another in time.

In an advantageous embodiment of the invention, the first vehicle is a vehicle driving ahead, the second vehicle is a vehicle driving behind, and the step of determining a distance between the first and second vehicles is carried out by the vehicle driving ahead. Thus, the first vehicle as the preceding vehicle can determine the distance directly and carry out the distance control in order to initiate a countermeasure if necessary. The preceding vehicle can quickly and efficiently reduce the distance to the following vehicle by braking. The vehicle driving ahead can also send control commands to the vehicle immediately following or to all vehicles following, based on the determined distance.

In an advantageous embodiment of the invention, the first vehicle is a following vehicle, the second vehicle is a preceding vehicle, and the step of determining a distance between the first and second vehicles is carried out by the following vehicle. The first vehicle, as the following vehicle, can thus determine the distance directly and carry out the distance control in order to initiate countermeasures if necessary. The following vehicle can quickly and efficiently increase the distance to the vehicle ahead by braking. There are no delays when the distance increases due to a signaling that may be required between the vehicles, so that the increase in the distance can be effected quickly and reliably. In addition, the following vehicle can send control commands to the vehicle in front or to all vehicles in the convoy based on the determined distance.

According to the invention, the method comprises an additional step for transmitting the distance between the first and second vehicle from the first vehicle to the second vehicle via a communication link. This includes a transmission of the distance, a result of the distance control or a control command to change the distance between the two vehicles, so that both vehicles can actively establish a desired distance. Thereby, the distance keeping control with the first and second vehicles is performed in unison. The combination of the control functions allows the second vehicle to be controlled while also taking into account the control of the first vehicle. Control as a countermeasure based on the distance control may be performed by both the first vehicle and the second vehicle, or in combination, that is, when reduced of the distance between vehicles, the vehicle in front may accelerate, the vehicle behind may decelerate, or both. The same applies vice versa when the distance increases.

In an advantageous embodiment of the invention, the method includes a step for receiving a speed of the first and/or the second vehicle. The vehicles and thus the vehicle convoy as a whole can carry out further measures based on the distance control, taking the speed into account as well. If the distance between the two vehicles decreases, a braking maneuver can be adjusted depending on the speed. At high speeds, for example, emergency braking can be initiated, while at low speeds a less intensive braking maneuver is carried out. The same applies in principle to acceleration, since greater air resistance occurs at higher speeds, which makes acceleration more difficult.

In an advantageous embodiment of the invention, the method includes an additional step for focusing the first ultrasonic signals emitted by the first vehicle and an additional step for focusing the second ultrasonic signals emitted by the second vehicle. This relates to a corresponding activation of the respective ultrasonic sensor. Alternatively or additionally, a hardware modification of the respective ultrasonic sensor is also possible. By focusing the ultrasonic signals emitted by the first or second vehicle, a greater range of the ultrasonic signals can be achieved, which makes it easier to use conventional ultrasonic sensors. Energy of the first or second ultrasonic signals emitted by the first or second vehicle can be bundled so that the respective other vehicle receives the ultrasonic signal at a sufficiently high level. When focusing purely by changing the control, the ultrasonic sensors can be used for distance control according to the present invention as well as in a known manner for detecting obstacles, for example when parking, in which case each ultrasonic sensor itself receives echoes of the ultrasonic signals emitted by it in order to determine a distance between the objects capture.

In an advantageous embodiment of the invention, the method includes an additional step for attaching the ultrasonic sensor to the first and/or second vehicle at a height of at least 80 cm above ground level, preferably at least one meter above ground level, particularly preferably at least 1.25 meters above ground level . Attaching the ultrasonic sensor at an appropriate height helps to prevent reflections of the ultrasonic signals, for example on a road surface. In particular, when the ultrasonic sensors are attached to a truck, a corresponding height can easily be achieved.

In an advantageous embodiment of the invention, the method includes an additional step for adjusting a distance between the first and the second vehicle based on the determined distance. In principle, the distance can be adjusted by decelerating and/or accelerating at least one of the vehicles. The adaptation can be carried out by the first vehicle or the second vehicle or both vehicles together. In addition, signaling can be carried out between the first and second vehicle in order to jointly carry out the adjustment of the distance. The adjustment can be made by changing the speed of the vehicle in front, i.e. decelerating or accelerating, or by changing the speed of the following vehicle, i.e. decelerating or accelerating. This can include the following vehicle carrying out emergency braking, for example if the distance control of the distance between the two vehicles shows that the distance is less than a minimum distance.

In an advantageous embodiment of the invention, the step of emitting first or second ultrasonic signals from the first or second vehicle includes emitting coded first or second ultrasonic signals. The transmission of coded ultrasonic signals allows the ultrasonic signals to be assigned to a specific vehicle or even to an individual ultrasonic sensor. Accordingly, each vehicle or each ultrasonic sensor emits encoded ultrasonic signals with an individual code. The code can be different for each vehicle. Confusion when receiving the ultrasonic signals can be avoided, as a result of which a change in the distance between two vehicles can be determined with a high level of reliability.

In an advantageous embodiment of the invention, the step of emitting coded first or second ultrasonic signals includes emitting the first and second ultrasonic signals with a corresponding first or second code. Thus, for example, on the part of the first vehicle, echoes of the first ultrasonic signals can be distinguished from the second ultrasonic signals. The second ultrasonic signals can be reliably identified to determine the distance between to be able to reliably determine the first and second vehicle. Confusion of the second ultrasonic signals with echoes of the first ultrasonic signals or with other ultrasonic signals can be avoided with appropriate coding.

In an advantageous embodiment of the invention, the method includes an additional step for receiving echoes of the first ultrasonic signals emitted by the first vehicle. By receiving and evaluating the echoes of the first ultrasonic signals, the echoes of the first ultrasonic signals can also be used to determine distances. A corresponding activation of at least one ultrasonic sensor of the first vehicle is required in order to receive the echoes of the first ultrasonic signals with the first code. In particular, the echoes may be received when the distance between the first and second vehicles is within a sensor range of the ultrasonic sensors in typical use.

In an advantageous embodiment of the invention, the method includes an additional step for emitting third ultrasonic signals from the second vehicle and receiving echoes of the third ultrasonic signals emitted by the second vehicle. The ultrasonic sensors of the second vehicle can also be used to collect distance information in the usual way. In this case, the echoes of the third ultrasonic signals can be distinguished, for example, from the first ultrasonic signals emitted by the first vehicle, in order to prevent interference. In particular, the echoes may be received when the distance between the first and second vehicles is within a sensor range of the ultrasonic sensors in typical use. In principle, echoes of the second ultrasonic signals can also be used to collect distance information in the usual way.

In an advantageous embodiment of the invention, the step of emitting first or second ultrasonic signals from the first or second vehicle comprises emitting ultrasonic signals with a modulated information signal, and the step of receiving the first or second ultrasonic signals with a second or first vehicle includes demodulating the ultrasonic signals and receiving the information signal. The modulation is preferably carried out according to the BPSK standard. In principle, the information signal can contain any information. For example, the information signal can be used for communication between the first and second vehicles in order to jointly control the vehicles in the platoon.

The invention is explained in more detail below with reference to the attached drawing based on preferred embodiments. The features shown can represent an aspect of the invention both individually and in combination. Features of different exemplary embodiments can be transferred from one exemplary embodiment to another.

• 1 eine schematische Ansicht einer Fahrzeugkolonne mit einer Mehrzahl Fahrzeuge beim Fahren auf einer Fahrbahn gemäß einer ersten, bevorzugten Ausführungsform,
• 2 eine detaillierte Ansicht von zwei Fahrzeugen der Fahrzeugkolonne aus 1 mit Ultraschallsensoren und einer Kommunikationsverbindung zur Durchführung eines Verfahrens zur Abstandskontrolle in Übereinstimmung mit der ersten Ausführungsform,
• 3 eine schematische Detailansicht eines Fahrzeugs in Übereinstimmung mit der Fahrzeugkolonne aus 1 mit einem Fahrunterstützungssystem zur Durchführung eines Verfahrens zur Abstandskontrolle in Übereinstimmung mit der ersten Ausführungsform,
• 4 ein Ablaufdiagramm eines Verfahrens zur Abstandskontrolle für die Fahrzeuge der Fahrzeugkolonne aus 1 in Übereinstimmung mit der ersten Ausführungsform,
• 5 eine schematische Ansicht einer Abstandsmessung basierend auf einem von einem ersten Fahrzeug ausgesendeten ersten Ultraschallsignal und einem von dem ersten Fahrzeug empfangenen Echo des ersten Ultraschallsignals, und
• 6 eine schematische Ansicht einer Abstandsmessung basierend auf einem von einem ersten Fahrzeug ausgesendeten ersten Ultraschallsignal und einem von dem zweiten Fahrzeug als Antwort auf einem Empfang des ersten Ultraschallsignals ausgesendeten zweiten Ultraschallsignals.

It shows

• 1 a schematic view of a vehicle convoy with a plurality of vehicles driving on a roadway according to a first preferred embodiment,
• 2 a detailed view from two vehicles of the motorcade 1 with ultrasonic sensors and a communication link for performing a method for distance control in accordance with the first embodiment,
• 3 Figure 12 shows a schematic detail view of a vehicle in accordance with the platoon of vehicles 1 with a driving support system for performing a distance control method in accordance with the first embodiment,
• 4 a flow chart of a method for distance control for the vehicles in the vehicle convoy 1 in accordance with the first embodiment,
• 5 a schematic view of a distance measurement based on a first ultrasonic signal emitted by a first vehicle and an echo of the first ultrasonic signal received by the first vehicle, and
• 6 a schematic view of a distance measurement based on a first ultrasonic signal emitted by a first vehicle and a second ultrasonic signal emitted by the second vehicle in response to a reception of the first ultrasonic signal.

The 1 shows a motorcade 10 with a plurality of vehicles 12 driving on a roadway 14 according to a first preferred embodiment of the invention.

The vehicle convoy 10 is shown here as an example with four vehicles 12, but in other exemplary embodiments it can, in principle, comprise any number of vehicles 12 that are designed in different ways. Vehicles 12 are in 1 designed as trucks, which have a distance 32 of, for example, seven to twelve meters between them. All vehicles 12 following a vehicle 12 leading the vehicle platoon 10 include a driving support system 16 that controls the driving of each vehicle 12 in the vehicle platoon 10 .

A vehicle 12 with a driving support system 16 is shown in FIG 3 shown. Even if the vehicle is 12 in 3 is shown as a passenger car, the principles of the driving support system 16 and its design can easily be transferred to other vehicle types. The statements relating to the vehicle 12 of 3 apply to all vehicles 12 considered here and vice versa.

In this exemplary embodiment, the driving support system 16 comprises two front, first ultrasonic sensors 18, which are attached to a front 22 of the vehicle 12 in relation to a direction of travel 20, and two rear, second ultrasonic sensors 24, which are attached to a rear end in relation to the direction of travel 20 26 of the vehicle 12 are attached. The first and second ultrasonic sensors 18, 24 are mounted on the first and second vehicles 12 at a height of approximately one meter above ground level. In this exemplary embodiment, the first vehicle 12 is a following vehicle 12 and the second vehicle 12 is a preceding vehicle 12.

The driving support system 16 also includes a control unit 28 which is connected to the first and second ultrasonic sensors 18 , 24 via a communication bus 30 . The first and second ultrasonic sensors 18, 24 are attached to the respective vehicle 12, for example, at a height of approximately 1.25 meters above ground level.

The driving assistance system 16 is designed to monitor distances 32 between a vehicle 12 driving ahead and a vehicle 12 following behind as part of a distance control. As a result, the vehicles 12 of the vehicle convoy 10 can jointly carry out a method for checking the distance between two vehicles 12, as is described in detail below. The method is described here in connection with driving in a motorcade 10 .

Hereinafter, a method of controlling the distance between two vehicles 12 for traveling in the vehicle platoon 10 will be described with reference to FIG 4 described. The method also includes a distance correction based on the distance control. The method is with additional reference to the 2 , 5 and 6 described. Individual process steps can also be carried out in a different order than that given here or simultaneously, as is obvious to the person skilled in the art.

The method begins here in step S100 with the first, following vehicle 12 emitting first ultrasonic signals 34 . The first ultrasonic signals 34 are emitted here independently of received ultrasonic signals, since receiving takes place independently in a subsequent step.

The first ultrasonic signal 34 is encoded before transmission, here with a BPSK code 0. In this case, successive first ultrasonic signals 34 are encoded differently in order to be able to identify and distinguish these first ultrasonic signals 34 by means of the encoding.

The other first ultrasonic sensor 18 of the first vehicle 12 is passive for receiving ultrasonic signals during the transmission of the first ultrasonic signal 34 . Immediately after the transmission of the first ultrasonic signal 34, the first ultrasonic sensor 18 also changes to a passive mode until it emits a first ultrasonic signal 34 again.

The point in time at which the respective first ultrasonic signal 34 was emitted is recorded.

In step S110 the first ultrasonic signal 34 emitted by the first ultrasonic sensor 18 of the first vehicle 12 is received by the second ultrasonic sensors 24 at the rear end 26 of the second vehicle 12 driving ahead. In this case, a beginning of the respective first ultrasonic signal 34 is used as a so-called trigger. The first ultrasonic signal 34 is decoded with BPSK code 0. If the received first ultrasonic signal 34 cannot be correctly decoded, the received first ultrasonic signal 34 is discarded. When the first ultrasonic signal 34 is received, a trigger is triggered on the received first ultrasonic signal 34, which trigger indicates the time at which the first ultrasonic signal 34 was received.

In step S120, one of the second ultrasonic sensors 24 of the second vehicle 12 sends a second ultrasonic signal 36 with a predetermined delay to the received first ultrasonic signal 34. The other second ultrasonic sensors 24 of the second vehicle 12 are passive for receiving first ultrasonic signals 34. The transmission of the second Ultrasonic signals 36 is therefore independent of the reception of the first Ultra sound signals 34. The delay is globally specified for all vehicles 12 and is 5 ms here, for example, to the trigger upon receipt of the first ultrasonic signal 34.

The second ultrasonic signal 36 is coded before transmission, here with a BPSK code 1. The second ultrasonic signal 36 is coded depending on the coding of the previously received first ultrasonic signal 34 in order to identify the second ultrasonic signal 36 as a response to the corresponding first ultrasonic signal 34 . The associated first and second ultrasonic signals 34, 36 therefore contain the same identification.

In step S130 the second ultrasonic signal 36 emitted by the second ultrasonic sensor 24 of the second vehicle 12 is received by one of the first ultrasonic sensors 18 on the front side 22 of the first vehicle 12 . In this case, the beginning of the second ultrasonic signal 36 is used as a trigger. The second ultrasonic signal 36 is decoded with BPSK code 1. If the received second ultrasonic signal 36 cannot be correctly decoded, the received second ultrasonic signal 36 is discarded. The identification of the second ultrasonic signal 36 is determined during decoding.

When the second ultrasonic signal 36 is received, a trigger is triggered on the received second ultrasonic signal 36, which trigger indicates the time at which the second ultrasonic signal 36 was received.

A signal path from the transmission of the first ultrasonic signal 34 in step S100 to the reception of the second ultrasonic signal 36 in step S130 is in 6 shown.

In step S140, a time difference between the transmission of the first ultrasonic signal 34 and the reception of the second ultrasonic signal 36 by the first vehicle 12 is determined. This is carried out in the control unit 28 of the second vehicle 12 . Based on the identification of the second ultrasonic signal 36, the point in time at which the associated first ultrasonic signal 34 was transmitted is determined.

Step S150 relates to receiving echoes 38 of the first ultrasonic signals 34 emitted by the first vehicle 12. The reception of the echoes 38 based on the first ultrasonic signals 34 is in 5 shown.

A beginning of the echo 38 is used as a trigger. The echo 36 is decoded with BPSK code 0 in accordance with the encoding of the first ultrasonic signal 34. If the received echo 38 of the first ultrasonic signal 34 cannot be correctly decoded, the received echo 38 is discarded. When the echo 38 of the first ultrasonic signal 34 is received, a trigger is triggered on the received echo 38 which indicates the time at which the echo 38 of the first ultrasonic signal 34 was received.

Steps S130 and S150 are basically identical and differ only in the further processing of the received signal. Depending on the coding of the received signal with BPSK code 0 or BPSK code 1, it can be distinguished whether it is an echo 38 of the first ultrasonic signal 34 or a second ultrasonic signal 36. Therefore, the reception of echoes 38 of the first ultrasonic signal 34 and the second ultrasonic signal 36 are carried out together.

In step S160 the distance 32 between the first and second vehicles 12 is determined by the first vehicle 12 . The distance 32 is initially determined based on the time difference determined in step S140 minus the delay. So the distance 32 is equal to (time difference - delay) divided by two multiplied by the speed of sound in air, which is 343 m/s at standard conditions.

In addition, if an echo 38 of the first ultrasound signal 34 was received in step S150, the distance 32 is performed based on a time difference between the transmission of the first ultrasound signal 34 and the reception of the echo 38. The distance 32 is therefore the time difference divided by two multiplied by the speed of sound in air.

The distance 32 can be determined independently in each case, both mathematically and in terms of time. In the case of small distances 32, which are in a receiving range of the echoes 38 of the first ultrasonic signal 34, the distance 32 between the vehicles 12 can be determined redundantly. In the case of larger distances, only the time difference based on the received second ultrasonic signal 36 is available as the basis for determining the distance 32.

In step S170 the distance 32 between the first and second vehicles 12 is transmitted from the first, following vehicle 12 to the second, preceding vehicle 12 via a communication link 40 . The communication link 40 is designed as a bi-directional communication link 40 .

In step S180, a speed of the first and second vehicles 12 is determined from that respective vehicle 12 determined. The speed is determined, for example, based on odometry data of the respective vehicle 12 or satellite position data, for example GPS, Galileo, Glonass, Beidou. Step S180 can be performed at any time. Step S180 is preferably repeated at a predetermined interval in order to always know a current vehicle 12 speed.

In step S190, the distance 32 between the first and second vehicles 12 is adjusted based on the determined distance 32 . This relates to a countermeasure to a change in the distance 12 between the two vehicles 12.

The distance 32 is first compared with a predefined distance 32 for distance control in order to determine deviations of the distance 32 from the predefined distance 32 . In particular, falling below a minimum distance between the two vehicles 12 is checked. A change in the distance 32 between the two vehicles 12 is also dynamically determined for distance control based on distance determinations that follow one another in time. This occurs independently in the first and second vehicle 12 .

Distance 32 is adjusted by decelerating and/or accelerating each of the two vehicles 12 together. This includes an emergency braking of the following vehicle, for example, when the distance control of the distance 32 between the two vehicles 12 shows that the distance falls below a minimum distance, depending on the determined speed.

Control of the distance 32 as a countermeasure based on the distance control is performed by the first vehicle 12 and the second vehicle 12 in combination. Correspondingly, if the distance 32 between the vehicles 12 decreases, the vehicle 12 driving ahead will accelerate and the vehicle 12 following behind will decelerate. The same applies vice versa when the distance 32 increases.

In addition, the leading vehicle 12 of the vehicle convoy 10 with its environment sensors leads in a 1 detection area 42 shown detects potential dangers for the vehicle convoy 10 . When a hazard is detected, the leading vehicle 12 starts decelerating the entire convoy of vehicles 10 in that the leading vehicle 12 starts a braking process and also sends a corresponding signal to all following vehicles 12 via the communication link 40 so that they also decelerate. The deceleration takes place with the same intensity in each case in order to keep the distance 32 between the vehicles 12 of the vehicle column 10 constant during the deceleration.

Reference List

10

motorcade

12

vehicle

14

roadway

16

driving support system

18

first ultrasonic sensor

20

driving direction

22

front

24

second ultrasonic sensor

26

back end

28

control unit

30

communication bus

32

Distance

34

first ultrasonic signal

36

second ultrasonic signal

38

echo

40

communication link

42

detection range

Claims (13)

Method for checking the distance between two vehicles (12) with the following steps: emitting first ultrasonic signals (34) from a first vehicle (12), receiving the first ultrasonic signals (34) emitted by the first vehicle (12) with a second vehicle (12) , Emitting a second ultrasonic signal (36) from the second vehicle (12) with a predetermined delay to each received first ultrasonic signal (34), Receiving the second ultrasonic signals (36) emitted by the second vehicle (12) with the first vehicle (12 ), determining a time difference between the transmission of the first ultrasonic signal (34) and the receipt of the second ultrasonic signal (36) by the first vehicle (12), and determining a distance (32) between the first and second vehicle (12) based on the Time difference minus the deceleration by the first vehicle (12), characterized in that the method includes an additional step of transmitting the distance (32) between the first and second vehicle (12) from the first vehicle (12) to the second vehicle (12) via a communication link (40). procedure after claim 1 , characterized in that the first vehicle (12) is a preceding vehicle (12), the second vehicle (12) is a following vehicle (12), and the step of determining a distance between the first and second vehicles (12) by the preceding vehicle (12) takes place. procedure after claim 1 , characterized in that the first vehicle (12) is a trailing vehicle (12), the second vehicle (12) is a leading vehicle (12), and the step of determining a distance between the first and second vehicles (12) by the following vehicle (12) takes place. Method according to one of the preceding claims, characterized in that the method comprises a step for receiving a speed of the first and/or the second vehicle (12). Method according to one of the preceding claims, characterized in that the method includes an additional step of focusing the first ultrasonic signals (34) emitted by the first vehicle (12) and an additional step of focusing the second ultrasonic signals ( 36) included. Method according to one of the preceding claims, characterized in that the method comprises an additional step of attaching the ultrasonic sensor (18, 24) to the first and/or second vehicle (12) at a height of at least 80 cm above ground level, preferably at least one meter above ground level, more preferably at least 1.25 meters above ground level. Method according to one of the preceding claims, characterized in that the method comprises an additional step for adjusting a distance (32) between the first and the second vehicle (12) based on the determined distance (32). Method according to one of the preceding claims, characterized in that the step of emitting first or second ultrasonic signals (34, 36) from the first or second vehicle (12) comprises emitting coded first or second ultrasonic signals (34, 36) includes. Procedure after the previous one claim 8 , characterized in that the step of emitting encoded first and second ultrasonic signals (34, 36) comprises emitting the first and second ultrasonic signals (34, 36) with a corresponding first and second code. Method according to one of the preceding claims, characterized in that the method comprises an additional step for receiving echoes (38) of the first ultrasonic signals (34) emitted by the first vehicle (12). Method according to one of the preceding claims, characterized in that the method comprises an additional step for emitting third ultrasonic signals from the second vehicle (12) and receiving echoes (38) of the third ultrasonic signals emitted by the second vehicle (12). Method according to one of the preceding claims, characterized in that the step of emitting first or second ultrasonic signals (34, 36) from the first or second vehicle (12) comprises emitting ultrasonic signals (34, 36) with a modulated information signal , and the step of receiving the first and second ultrasonic signals (34, 36) with a second and first vehicle (12), respectively, comprises demodulating the ultrasonic signals (34, 36) and receiving the information signal. Motorcade (10) with a plurality of vehicles (12), wherein the vehicles (12) of the motorcade (10) are designed, the method according to one of the preceding Claims 1 until 12 to perform.

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