CN111645649B - Method for controlling a vehicle fleet during emergency braking - Google Patents

Method for controlling a vehicle fleet during emergency braking Download PDF

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Publication number
CN111645649B
CN111645649B CN202010045767.1A CN202010045767A CN111645649B CN 111645649 B CN111645649 B CN 111645649B CN 202010045767 A CN202010045767 A CN 202010045767A CN 111645649 B CN111645649 B CN 111645649B
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motor vehicle
vehicle
time
deceleration
braking
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CN111645649A (en
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F·拜廷格
U·古克尔
A·穆斯塔法
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Knorr Bremse Systeme fuer Nutzfahrzeuge GmbH
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Knorr Bremse Systeme fuer Nutzfahrzeuge GmbH
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    • BPERFORMING OPERATIONS; TRANSPORTING
    • B60VEHICLES IN GENERAL
    • B60TVEHICLE BRAKE CONTROL SYSTEMS OR PARTS THEREOF; BRAKE CONTROL SYSTEMS OR PARTS THEREOF, IN GENERAL; ARRANGEMENT OF BRAKING ELEMENTS ON VEHICLES IN GENERAL; PORTABLE DEVICES FOR PREVENTING UNWANTED MOVEMENT OF VEHICLES; VEHICLE MODIFICATIONS TO FACILITATE COOLING OF BRAKES
    • B60T7/00Brake-action initiating means
    • B60T7/12Brake-action initiating means for automatic initiation; for initiation not subject to will of driver or passenger
    • B60T7/22Brake-action initiating means for automatic initiation; for initiation not subject to will of driver or passenger initiated by contact of vehicle, e.g. bumper, with an external object, e.g. another vehicle, or by means of contactless obstacle detectors mounted on the vehicle
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B60VEHICLES IN GENERAL
    • B60TVEHICLE BRAKE CONTROL SYSTEMS OR PARTS THEREOF; BRAKE CONTROL SYSTEMS OR PARTS THEREOF, IN GENERAL; ARRANGEMENT OF BRAKING ELEMENTS ON VEHICLES IN GENERAL; PORTABLE DEVICES FOR PREVENTING UNWANTED MOVEMENT OF VEHICLES; VEHICLE MODIFICATIONS TO FACILITATE COOLING OF BRAKES
    • B60T7/00Brake-action initiating means
    • B60T7/12Brake-action initiating means for automatic initiation; for initiation not subject to will of driver or passenger
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B60VEHICLES IN GENERAL
    • B60WCONJOINT CONTROL OF VEHICLE SUB-UNITS OF DIFFERENT TYPE OR DIFFERENT FUNCTION; CONTROL SYSTEMS SPECIALLY ADAPTED FOR HYBRID VEHICLES; ROAD VEHICLE DRIVE CONTROL SYSTEMS FOR PURPOSES NOT RELATED TO THE CONTROL OF A PARTICULAR SUB-UNIT
    • B60W30/00Purposes of road vehicle drive control systems not related to the control of a particular sub-unit, e.g. of systems using conjoint control of vehicle sub-units
    • B60W30/14Adaptive cruise control
    • B60W30/16Control of distance between vehicles, e.g. keeping a distance to preceding vehicle
    • B60W30/162Speed limiting therefor
    • GPHYSICS
    • G08SIGNALLING
    • G08GTRAFFIC CONTROL SYSTEMS
    • G08G1/00Traffic control systems for road vehicles
    • G08G1/16Anti-collision systems
    • G08G1/161Decentralised systems, e.g. inter-vehicle communication
    • G08G1/162Decentralised systems, e.g. inter-vehicle communication event-triggered
    • GPHYSICS
    • G08SIGNALLING
    • G08GTRAFFIC CONTROL SYSTEMS
    • G08G1/00Traffic control systems for road vehicles
    • G08G1/16Anti-collision systems
    • G08G1/166Anti-collision systems for active traffic, e.g. moving vehicles, pedestrians, bikes
    • GPHYSICS
    • G08SIGNALLING
    • G08GTRAFFIC CONTROL SYSTEMS
    • G08G1/00Traffic control systems for road vehicles
    • G08G1/22Platooning, i.e. convoy of communicating vehicles
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B60VEHICLES IN GENERAL
    • B60TVEHICLE BRAKE CONTROL SYSTEMS OR PARTS THEREOF; BRAKE CONTROL SYSTEMS OR PARTS THEREOF, IN GENERAL; ARRANGEMENT OF BRAKING ELEMENTS ON VEHICLES IN GENERAL; PORTABLE DEVICES FOR PREVENTING UNWANTED MOVEMENT OF VEHICLES; VEHICLE MODIFICATIONS TO FACILITATE COOLING OF BRAKES
    • B60T2201/00Particular use of vehicle brake systems; Special systems using also the brakes; Special software modules within the brake system controller
    • B60T2201/02Active or adaptive cruise control system; Distance control

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  • Engineering & Computer Science (AREA)
  • Transportation (AREA)
  • Mechanical Engineering (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Automation & Control Theory (AREA)
  • Traffic Control Systems (AREA)
  • Regulating Braking Force (AREA)

Abstract

The invention relates to a method for controlling a vehicle fleet, which is informed via a V2V communication (14) to a vehicle (2, 4,6,8, 10) behind the vehicle fleet and in particular also to a vehicle (2) immediately behind the vehicle fleet, as soon as emergency braking is activated for any vehicle (1) in the vehicle fleet (100). All following vehicles then also assume emergency braking. In this case, each motor vehicle (1, 2,4,6,8, 10) is first braked with its maximum possible deceleration. The vehicle braked emergently transmits its instantaneous longitudinal deceleration, speed and distance (d) from the vehicle (1) running ahead continuously to the other vehicles braked emergently by means of a V2V communication (14). By means of these values, the respective preceding vehicle (1) can calculate by means of the method the maximum deceleration at which it is permitted to brake in order to avoid a collision with the vehicle (2) immediately behind.

Description

Method for controlling a vehicle fleet during emergency braking
Technical Field
The invention relates to a method for controlling a vehicle fleet comprising a first motor vehicle traveling ahead and at least one second motor vehicle directly following the first motor vehicle traveling ahead in an electronically coupled manner.
Background
When driving in a fleet, the electronic coupling can be automated at least for the motor vehicles following the head vehicle, so that autonomous driving is possible for the motor vehicles following the head vehicle. The vehicle driver of the following motor vehicle no longer has to monitor the traffic conditions by itself during the driving of the fleet. It is therefore known to electronically couple motor vehicles in such a way that they travel as compactly as possible one behind the other, longitudinally and optionally also transversely adjusted.
Such an electronically or loosely coupled platoon thus comprises a first lead vehicle and a tail vehicle and possibly intermediate motor vehicles. In this case, the respective following vehicle is optically oriented toward the preceding vehicle. The motor vehicles of such a vehicle fleet are equipped with a device for inter-vehicle communication (V2V communication), wherein data relating to the vehicles, such as the acceleration/deceleration and the speed of the individual motor vehicles, are transmitted to each participant of the vehicle fleet and in particular to the head vehicle. In addition, the current distance to the preceding vehicle is determined by the following vehicle rotation sensor and set to a predefined target value, for example 8 meters. For measuring the distance, for example, radar sensors or lidar sensors are used. In literature or literature, such electronically or loosely coupled groups or fleets of motor vehicles may also be referred to as "rows".
In a compact driving of a fleet of vehicles of about 80km/h, the air resistance of the fleet vehicles can be reduced by up to 30%. In this case, it is advantageous if the typical distance between a preceding vehicle and a vehicle following the preceding vehicle is in the range from 8m to 20m, in order to achieve a significant reduction in the air resistance. The smaller the spacing between the vehicles participating in the fleet, the lower the air resistance of the individual vehicles. In order to reduce the air resistance significantly, the spacing is very small, so that high demands are placed on the driver assistance system for automatically maintaining the spacing.
Exemplary methods for electronically coupling motor vehicles to a vehicle fleet are described in DE 10 2007 046 765A1 or EP 1 569 183A2.
In particular, the following requirements are made for the control and regulation of the fleet:
to comply with a defined tolerance with a short longitudinal distance (e.g. 8m-20 m) between the participating vehicles.
Automatically guiding the following vehicle laterally in the lane of the head vehicle as precisely as possible.
Ensuring the stability of the fleet, i.e. in particular avoiding the "accordion effect" (queue stability), which not only leads to an increase in energy consumption, but also significantly increases the risk of rear-end accidents. In this case, the queue stability is to be observed for the longitudinal guidance and the transverse guidance.
Small variations in the speed of the preceding vehicles of the fleet should not be enforced by the subsequent vehicles.
For guidance in the transverse direction, no tangency of the curve and thus lane departure should result in the trailing vehicle.
When the head vehicle is strongly braked, the rear vehicle reacts quickly enough to avoid a rear-end collision.
Compliance with the above requirements is often made difficult by the technical equipment and characteristics of the motor vehicles participating in the fleet, such as engine power, the ability to work with creep brakes or service brakes, vehicle design, load conditions, and tire characteristics.
A dilemma arises in the case of, for example, a sudden occurrence of an obstacle in front of the head car of a fleet of cars, which either forces the driver of the head car or the automatic driving device of the head car to make an emergency brake at the maximum possible deceleration.
Since in practice the head vehicle can be braked with its maximum available deceleration in order to keep the risk of collision with the obstacle or the collision speed as low as possible. However, there is a risk of rear-end collisions of the motor vehicles in the vehicle fleet if there are motor vehicles in the vehicle fleet which can exert a lower maximum deceleration than the head vehicle, for example due to a weaker braking or a higher load.
Because the leading vehicle can brake at the maximum deceleration of the vehicle with the "weakest" braking of the fleet in order to prevent the following vehicles from colliding with each other. However, this results in the first vehicle braking at a relatively low deceleration, i.e. braking the "weakest" participant, because of the predetermined setpoint value determined in accordance with the braking of the "weakest" participant. Therefore, in this case, the risk of collision or the collision speed with the obstacle will increase.
Disclosure of Invention
The object of the invention is to further develop a method of the type mentioned above such that the safety of a vehicle fleet consisting of loosely coupled motor vehicles is increased.
This task is solved by the features of the preferred embodiments of the present invention.
According to the invention, the dilemma of driving and reversing described above can be solved by a method for controlling a vehicle fleet having a first vehicle traveling ahead and at least one second vehicle directly following the first vehicle traveling ahead in an electronically coupled manner, in which method the vehicles are moved along a travel route at least temporarily at a predeterminable, constant longitudinal distance from one another on the basis of a predeterminable overall operating strategy (vehicle fleet controller) associated with the vehicle fleet, wherein the first vehicle and the second vehicle exchange data with one another by means of inter-vehicle communication (V2V), the data relating to at least their instantaneous longitudinal deceleration and at least one variable representing the instantaneous longitudinal distance between the second vehicle and the first vehicle, the method comprising at least the following steps:
a) When the first motor vehicle is braked from the time of triggering of the emergency brake by the driver thereof and/or by the emergency brake triggered automatically in the first motor vehicle, the emergency brake of the first motor vehicle decelerates in the longitudinal direction from the time of triggering with a first deceleration value that is maximally possible for the first motor vehicle, wherein,
b) The triggering of the emergency braking in the first motor vehicle is communicated to the second motor vehicle by means of the inter-vehicle communication (V2V), whereupon the emergency braking with the second deceleration value that is the greatest possible for the second motor vehicle is triggered in the second motor vehicle essentially from the moment of triggering for longitudinal deceleration and
c) If, on the basis of the data exchanged between the first motor vehicle and the second motor vehicle, it is detected at a first time later than the triggering time that the variable representing the longitudinal distance changes during a continuous emergency braking in such a way that there is a risk of the second motor vehicle colliding with the first motor vehicle, the longitudinal deceleration of the first motor vehicle is reduced at least in stages to a limited deceleration value which is smaller in magnitude than the maximum possible first deceleration value in such a way that the second motor vehicle is brought into contact with the first motor vehicle neither during the emergency braking nor in a state in which the first motor vehicle and the second motor vehicle are braked to a standstill.
However, if it is recognized, based on the data exchanged between the first motor vehicle and the second motor vehicle, at a first time later than the trigger time, that the variable representing the longitudinal distance does not change or changes during a continuous emergency braking in such a way that there is no danger of the second motor vehicle colliding with the first motor vehicle, then the (entire) emergency braking of the first motor vehicle is preferably carried out unchanged at the maximum possible first deceleration value.
"emergency braking" is to be understood as meaning, as is usual, full braking with the maximum available longitudinal deceleration.
Here, "longitudinal deceleration" is understood in a mathematical sense to mean a negative longitudinal acceleration, wherein a reduction or reduction of the longitudinal deceleration means a reduction of the magnitude of the longitudinal deceleration, for example from-6 m/s 2 Reduced to-5 m/s 2 . The same is true, in turn, for an increase or increase in the longitudinal deceleration, wherein the magnitude of the longitudinal deceleration increases, for example, from-5 m/s 2 Increase to-6 m/s 2
The first motor vehicle traveling in front is only the "first" motor vehicle in the sense that it travels in front of the rear "second" motor vehicle within the fleet. The "first" and "second" vehicles are therefore formed by a pairing of a preceding vehicle and a vehicle following the preceding vehicle within the electronically coupled fleet.
The first motor vehicle traveling ahead may be formed, for example, by the head vehicle of the vehicle fleet, which continuously commands the automatically loosely coupled vehicle fleet without leaving the guidance location. Alternatively, it is also possible to use a motor vehicle directly or indirectly following the head vehicle as the first motor vehicle of the vehicle fleet traveling ahead, which is braked or has to be braked by emergency braking when an obstacle external to the vehicle fleet, for example an external vehicle, enters the vehicle fleet ahead of this first motor vehicle traveling ahead and thus triggers a cut-off criterion for the vehicle fleet. In this case, the preceding first motor vehicle then forms the (new) head vehicle of the remaining vehicle group that is to be formed by the preceding first motor vehicle and at least the second motor vehicle following the first motor vehicle.
For example, when a driver or an autopilot suddenly detects an obstacle, such as a motor vehicle inserted in front of the first lead vehicle or a stationary obstacle, and therefore requires emergency braking of the first motor vehicle, and therefore also braking of the motor vehicle or the entire fleet of motor vehicles following the first motor vehicle, the first motor vehicle traveling ahead automatically undertakes an emergency braking process by means of an autopilot of the first motor vehicle traveling ahead and/or by the driver, depending on the detected environmental data.
In particular, the longitudinal spacing and/or the relative speed and/or the relative acceleration between the at least two vehicles of the vehicle fleet are used as the at least one variable which represents the longitudinal spacing between the at least two vehicles of the vehicle fleet. In this case, a variable representing the longitudinal distance between at least two motor vehicles of the vehicle train is measured or determined between two first motor vehicles directly following one another and a second motor vehicle.
Starting from the situation described above in which the braking or deceleration capacity of the individual motor vehicles of the electronically coupled fleet, i.e. the longitudinal deceleration which can be applied to the maximum during emergency braking, is unknown, the positive effect of the invention is that, in the event of a risk of a collision between a first and a second motor vehicle during emergency braking, the longitudinal deceleration of the preceding first motor vehicle is adapted or reduced from its maximum possible longitudinal deceleration value in such a way that no undue requirements are made on the braking or deceleration capacity of the following second motor vehicle and thus a collision between the two motor vehicles is avoided during emergency braking and also in the state of continuous braking. Thus, a "cooperative emergency braking" between a first vehicle traveling ahead and a second vehicle behind is proposed, wherein the decelerations of the two vehicles cooperate with each other as described above.
In order to avoid a collision with an obstacle, the second, rear motor vehicle is also preferably braked throughout the emergency braking process at a second deceleration value which is maximally possible for the longitudinal deceleration.
Further advantages are achieved by the features given in the alternative solutions, the figures and the description of the figures, with which further solutions of the invention are obtained.
According to a first variant of the invention, the limited deceleration value of the first motor vehicle is adapted continuously or continuously as a function of time from the first point in time. In other words, the limited deceleration value of the first motor vehicle is adapted continuously from the first instant in time.
This first variant of the method is based on the following conditions: in order to avoid a collision between the first and second motor vehicles during emergency braking, the braking distance of the first motor vehicle traveling in front must be greater than the braking distance of the second motor vehicle behind, minus the distance between the first motor vehicle and the second motor vehicle which exists at the time of triggering of the emergency braking.
Based on this condition, in a first variant of the method, the limited deceleration value of the first motor vehicle is then adapted continuously from the first time point as a function of the minimum permissible longitudinal distance and at least as a function of the following variables which are detected and which vary over time: the speed and longitudinal deceleration of the second vehicle, the speed of the first vehicle and the longitudinal spacing between the first vehicle and the second vehicle. Since the above-mentioned detected variables change over time after emergency braking has been triggered.
In particular, the limited deceleration value of the first motor vehicle is adapted from the first time as specified below:
Figure BDA0002369334680000071
wherein,
a 1,lim is the limited deceleration value of the first vehicle,
s 2 is the braking distance of the second motor vehicle,
d 2 is the longitudinal spacing between the first vehicle and the second vehicle,
d 2,min is the minimum allowable longitudinal spacing between the first vehicle and the second vehicle,
v 1 is the speed of the first motor vehicle,
braking distance s of the second motor vehicle 2 For example, as specified below:
Figure BDA0002369334680000081
according to a second variant of the present invention,
a) During a first time period starting from the triggering moment of the emergency braking and extending to the first moment, the first motor vehicle brakes with a maximum possible first deceleration value,
b) During at least one second time period starting at the first time and ending at a second time, the longitudinal deceleration of the first motor vehicle is reduced to the limited deceleration value, wherein the first motor vehicle decelerates with the limited deceleration value until the first speed of the first motor vehicle is substantially as great relative to the second speed of the second motor vehicle at the second time, and then
c) During a third time period starting at the second time and ending at a third time, at which a braking-to-standstill state of the first motor vehicle and the second motor vehicle is reached, the first motor vehicle brakes with a second deceleration value that is maximally possible for the second motor vehicle.
Preferably, the second motor vehicle is braked in the first, second and third time periods with the maximum possible second deceleration value.
According to a further aspect, during the at least one second time period, the limited deceleration value is smaller in magnitude than the maximum possible second deceleration value.
A second variant of the method therefore proposes: the emergency braking of the first motor vehicle traveling ahead is divided into, for example, three time phases with different longitudinal decelerations. In this case, the longitudinal deceleration of the second, following motor vehicle is assumed to be constant (for example the maximum possible second deceleration value) and the speeds of the first and second motor vehicles are assumed to be equal in magnitude at the time of triggering of the emergency braking.
When the emergency braking begins at the triggering time, the two motor vehicles are first braked in each case with their maximum possible deceleration value. From a first point in time, the preceding first motor vehicle reduces its deceleration to the limited deceleration value and holds it until a second point in time, at which both motor vehicles reach the same speed. The first motor vehicle traveling ahead is then decelerated at the maximum possible deceleration value of the second motor vehicle until the stop state of both motor vehicles is reached. During this time, the second motor vehicle is preferably decelerated at its maximum possible second deceleration value until standstill.
Further details of this second variant are obtained from the following description of the embodiment.
Preferably, the first motor vehicle traveling ahead automatically initiates an emergency braking process by means of the driver and/or by the automatic driving device of the first motor vehicle traveling ahead, as a function of the detected environmental data. These environmental data can be provided by the sensor system of the preceding first motor vehicle, but in part also by an external infrastructure.
According to a further development, the longitudinal distance and/or the relative speed and/or the relative acceleration between the preceding first motor vehicle and the following second motor vehicle is used as the at least one variable which represents the longitudinal distance.
Preferably, in addition to the activation of the braking device, a control signal for reducing the drive output of the drive motor of the first motor vehicle and of the second motor vehicle is generated during emergency braking of the first motor vehicle and of the second motor vehicle, respectively.
Drawings
Embodiments of the invention are illustrated in the drawings and will be described in detail in the following description. In the drawings:
FIG. 1: a schematic side view showing a fleet of vehicles that are loosely or electronically coupled to each other;
FIG. 2: a schematic top view of the fleet of fig. 1 is shown;
FIG. 3: schematic side views of a first vehicle and a second vehicle of the platoon of fig. 1 are shown;
FIG. 4: a schematic side view showing a first vehicle and a second vehicle of a cooperatively hard-braked fleet at four different times;
FIG. 5: diagrams are shown which represent the time profile of the longitudinal deceleration and of the speed in a second variant of the method according to the invention.
Detailed Description
Fig. 1 shows a schematic side view of a vehicle fleet 100 (rows) of motor vehicles which are loosely or electronically coupled to one another. The vehicle train 100 comprises the head vehicle 1 as the first or foremost lead vehicle and further motor vehicles, namely a second motor vehicle 2, a third motor vehicle 4, a fourth motor vehicle 6, a fifth motor vehicle 8 and a rearmost sixth motor vehicle 10. The fleet 100 may include more or fewer vehicles in addition to the six vehicles shown.
Fig. 2 shows a top view of a vehicle fleet 100 traveling in a left turn along a travel route traveled by the vehicle fleet 100. The six motor vehicles 1 to 10 thus each form a participant of the vehicle fleet 100. It is assumed here that the formation of the vehicle fleet 100 is complete, i.e. the motor vehicles 1 to 10 are to be understood to form a loosely coupled vehicle fleet 100 entirely from them.
In this exemplary embodiment, the motor vehicles 1 to 10 are heavy commercial vehicles, each of which has a drive machine that can be electrically controlled and is embodied here, for example, as an internal combustion engine, an electrically controllable electropneumatic service brake device, an electrically controllable electropneumatic parking brake and an electrically controllable steering device.
The motor vehicles or participants 1 to 10 of the fleet 100 can exchange data via on-board vehicle-to-vehicle communication means (V2V). In this case, it relates to a wireless inter-vehicle communication device, wherein each of the motor vehicles 1 to 10 is equipped with a transmitting device and a receiving device. Alternatively, the inter-vehicle communication device may also be embodied as a laser or infrared transmitting device and a receiving device. In fig. 2, inter-vehicle communication due to the inter-vehicle communication means is indicated by an arrow 14.
In addition, a wireless vehicle-infrastructure communication device (V2X) can also be provided, which is installed, for example, in each motor vehicle or in a participant 1 to 10 and also comprises a transmitting device and a receiving device. Each of these motor vehicles 1 to 10, and in particular the head car 1, can thus communicate with an external mobile or stationary infrastructure X.
Each of the six motor vehicles 1 to 10 is controlled or regulated by a common regulating strategy (vehicle group regulator or vehicle queue regulating device) of the vehicle group 100, which is based on the exchange of data by means of the inter-vehicle communication device (V2V) in respect of the respective driving conditions, such as speed, longitudinal deceleration, etc., of the individual motor vehicles 1 to 10, in such a way that the longitudinal distance d between the respective two of the motor vehicles 1 to 10 is regulated to a defined value d.
This enables the motor vehicles 2 to 10 to follow the front vehicle 1 at a distance from one another by the distance d.
For this purpose, first sensor devices are installed in the motor vehicles 1 to 10, which generate corresponding driving conditions, for example speed data and acceleration/deceleration data, with respect to a motor vehicle, which are then transmitted to the other motor vehicles and in particular to the headwear 1 via the inter-vehicle communication 14. Furthermore, a second sensor device is installed in the motor vehicles 1 to 10, which second sensor device generates second data with respect to the respective distance d, the relative deceleration or the relative acceleration between the relevant motor vehicle and the motor vehicle running before the relevant motor vehicle. The second data can also be transmitted to other vehicles and in particular to the head car 1 via the inter-vehicle communication 14. Furthermore, each of these motor vehicles 1 to 10 is equipped with an electronic control unit, in which control and regulation programs of the regulation strategy are implemented, which control and regulation programs operate on the basis of the first data and the second data.
For each motor vehicle 1 to 10, there are therefore a transmitting device and a receiving device of the vehicle-to-vehicle communication device (V2V), a sensor device, an electronic control unit, and at least one electrically controllable drive machine, an electrically controllable service brake device, and optionally also an electrically controllable steering device as actuators.
As a result of the distance and speed data received in each case by the electronic control unit, an automatic electrical actuation of the electropneumatic brake, the electrically controllable drive machine and optionally the electrical steering of each of the motor vehicles 1 to 10 incorporated into the fleet 100 takes place within the framework of a common control strategy of the fleet 100 by means of electrical control signals in order to follow a setpoint trajectory specified by the headwear 1, for example, at equal distances along a left turn (see fig. 2).
In this case, an "adjustment strategy" is to be understood to mean, in particular, a longitudinal adjustment of the motor vehicles 1 to 10 of the vehicle fleet 100, which is calculated from the first and second data of the individual motor vehicles 1 to 10 of the vehicle fleet 100 and from which adjustment values for the drive motor and/or for the individual motor vehicles 1 to 10 of the vehicle fleet 100 are then determined. Then, by intervening on the brake systems and/or the drive motors of the motor vehicles 1 to 10, a longitudinal guidance intervention can be carried out in addition to the transverse guidance intervention.
Furthermore, at least the head car 1 is equipped with an automatic driving device, for example, which allows the head car 1 to operate autonomously without driver action. Due to the autopilot, the vehicle head 1 is braked, for example, with an emergency brake or full brake, if an obstacle 16, for example in the form of an external motor vehicle, is present in the driving path of the vehicle head in a manner critical to safety. Then, emergency braking of the head vehicle 1 is carried out at a first deceleration value a which is the maximum possible for the longitudinal deceleration a of the head vehicle 1 1,max And (5) implementing. In the head car, the first deceleration value a is greater than the maximum possible first deceleration value a 1,max Higher deceleration values are not possible.
Then, emergency braking is also automatically triggered in the second motor vehicle 2 and in the further motor vehicles 4 to 10 by the vehicle-to-vehicle communication device (V2V) of the head vehicle 1 or the second motor vehicle 2.
In this situation, if, for example, the second vehicle 2 following the head car 1 has the largest possible second deceleration value a 2,max Should be greater than the maximum possible second of the head car 1A deceleration value a 1,max If the braking of the head vehicle 1 is small, that is to say if the braking of the head vehicle 1 is stronger than that of the second vehicle 2, it is necessary to limit the longitudinal deceleration of the head vehicle 1 in order to prevent the second vehicle 2 from hitting the rear of the head vehicle 1 during the emergency braking.
Fig. 3 shows the initial situation of the head car 1 and the second motor vehicle 2 before the emergency braking is triggered. In this case, the first motor vehicle 1 and the second motor vehicle 2 each have a speed v in the sense of a regulation strategy of the vehicle fleet 100 0 And move with a distance d2 from each other. As mentioned above, the maximum possible first deceleration value a of the primary vehicle 1 1,max Greater than the maximum possible second deceleration value a of the second vehicle 2 2,max
The emergency braking process is now illustrated in fig. 4.
At time t = t 0 (uppermost illustration in fig. 4), the head car 1 is at a distance d by means of a sensor device available for it 1,0 An obstacle in the form of, for example, an outside vehicle 16 is identified. Then, for example, the autopilot device in the head car 1 assumes emergency braking or full braking, which then takes place at a first deceleration value a that is maximally possible for the longitudinal deceleration 1,max And (5) implementing. The emergency braking triggered situation in the head car 1 is communicated without delay to the second motor vehicle 2 via a V2V communication, which then also assumes emergency braking substantially simultaneously, but at the maximum possible second deceleration value a 2,max Implemented, however, in a magnitude smaller than said maximum possible first deceleration value a 1,max The head vehicle 1 brakes at this maximum possible first deceleration value. In this regard, the time t = t 0 A triggering moment for triggering the emergency braking in both vehicles 1 and 2 is formed. At the trigger time t = t 0 An initial spacing d exists between the two vehicles 1,2 2,0 And the head vehicle 1 is at a speed v 1 Moving, the second vehicle behind at a speed v 2 Exercise wherein v 1 =v 2 =v 0 (FIG. 3).
At a time t relative to the trigger 0 Late first time t = t 1 (from above in FIG. 4)Several second diagrams), the second motor vehicle 2 continuously evaluates the distance d to the head vehicle 1 2 A second deceleration value a is identified despite this maximum possible 2,max Still face the risk of collision because of the distance d 2 Have become smaller. The second motor vehicle 2 signals the head vehicle 1 via V2V communication that the following information is required: reducing its deceleration to avoid collisions.
At a time relative to the first time t 1 A second later time t = t 2 (third from the top in FIG. 4), the head car is braked to a standstill and travels over a braking distance s during its braking process 1
At a time t relative to the second time 2 Late third time t = t 3 (fourth illustration from above in fig. 4), the second motor vehicle 2 is now also braked to a standstill and at a minimum safety distance d min Stopping behind the head car, wherein the second motor vehicle travels over a braking distance s during braking of the second motor vehicle 2
Two variants for reducing the deceleration of the head vehicle 1 are now proposed to avoid collisions:
continuously reducing deceleration
The scheme of continuously or continuously reducing the deceleration of the head car 1 comes from the following conditions: braking distance s of the head car 1 1 Must be greater than the braking distance s of the second motor vehicle 2 2 Minus the initial distance d 2,0 . The deceleration of the head car 1 should be from the maximum possible first deceleration value a 1,max Limiting or reducing to a deceleration value a 1,lim So that the second motor vehicle 2 does not collide with the head vehicle 1 and is thereby, for example, at a minimum safety distance d min Stopping behind the head car 1.
To determine a 1,lim Calculating the braking distance s of the second motor vehicle 2
Figure BDA0002369334680000141
Thereby, the limited deceleration value a of the head vehicle 1 1,lim Comprises the following steps:
Figure BDA0002369334680000151
then, using the variable that varies over time t during emergency braking: speed v of the head car 1 Speed v of the second motor vehicle 2 2 And longitudinal deceleration a 2 And the longitudinal distance d between the two vehicles 1 and 2 2 Can be calculated by equation (2) over a time interval t 0 ,t 3 ]At each point in time t of the inherent continuous emergency braking, a limited deceleration value a is calculated for the head car 1, which value depends on the time t 1,lim =a 1,lim (t)。
Varying deceleration in multiple time steps
Another variant for limiting or reducing the deceleration of the vehicle head 1 consists in dividing the emergency braking into different deceleration values a in each case 1,I 、a 1,II 、a 1,III A plurality of time periods t I ,t II And t III . Here, the deceleration a of the second motor vehicle 2 is assumed 2 Is constant and should correspond, for example, to the maximum possible second deceleration value a during the entire emergency braking 2,max . At the triggering time t of the cooperative emergency braking 0 It should also be assumed before that the initial speeds v of the two vehicles 1 and 2 1 And v 2 The same is true.
As shown in the left diagram of fig. 5, at the time t of triggering of the emergency braking 0 The two vehicles 1 and 2 are first of all at their respective maximum possible deceleration values a 1,max And a 2,max Braking, wherein a first deceleration value a of the head car 1 is associated with a time period 1 (t) is shown in dashed lines and the time interval [ t ] of the second motor vehicle 2 0 ,t 3 ]Second deceleration value a of (1) assumed to be constant 2 (t) is shown in solid lines.
At a first time t 1 In the first variant described above, the front vehicle 1 is requested by the second motor vehicle 2 to reduce its longitudinal deceleration, from the first time t 1 Initially, the head car 1 reduces its longitudinal deceleration to a value a 1,II And holds this value until a second time t 2 At this second time, the two vehicles 1 and 2 have the same speed v, as shown in the right-hand diagram of fig. 5, in which the time profile v of the first speed of the head vehicle 1 is shown 1 (t) and a time profile v of a second speed of the second motor vehicle 2 2 (t)。
Then, from the second time t 2 Initially, the primary vehicle 1 assumes the deceleration of the second vehicle and at a third time t 3 Is braked to a standstill, wherein 1,III =a 2,max
Thus, the head carriage 1 as a whole has different, but corresponding phases t in each of the three phases I ,t II And t III Medium constant deceleration value a 1,I 、a 1,II 、a 1,III Of phases t directly following each other in time I ,t II And t III Middle braking:
stage t I Time interval [ t 0 ,t 1 ]:a 1,I =a 1,max
Stage t II Time interval [ t 1 ,t 2 ]:a 1,II <a 2,max <a 1,max
Stage t III Time interval [ t 2 ,t 3 ]:a 1,II =a 2,max
Here, the boundaries of two adjacent time intervals are simply calculated as these two time intervals.
The area Δ d is shown in fig. 5 by hatching 2,I And Δ d 2,II The sum of these areas corresponding to the reduced distance Δ d during braking 2 . Therefore, the first deceleration a of the head vehicle 1 1 Must be determined such that the distance d between the vehicles 1,2 2 During the emergency braking, the maximum distance d is reduced to the minimum 2,min Without causing a collision here.
Δd 2 Can be measured by the speed difference Δ v = v 2 (t)-v 1 (t) at a time period t I And t II Product of upperRespectively determining:
Figure BDA0002369334680000161
Figure BDA0002369334680000162
in a first phase t I During which the increased speed difference Δ v (t) 1 ) In the second stage t II The duration is again reduced. Thus, for a time phase or period t I And t II The following relationship is obtained for the ratio between:
Figure BDA0002369334680000163
initial spacing Δ d 2,0 Should be given Δ d during braking 2 Reduced to the lowest safety distance d 2,min
Figure BDA0002369334680000164
Figure BDA0002369334680000165
By using this relationship, the deceleration value a after the limitation can be obtained 1,II Determining a time period t I And t II
Figure BDA0002369334680000171
If the initial speeds of the two vehicles are different (v) 1 ≠v 2 ) Then an additional time error t is obtained ev And pitch error Δ d ev
Figure BDA0002369334680000172
Figure BDA0002369334680000173
At the calculation time t I The time and spacing errors must be considered as follows:
Figure BDA0002369334680000174
limited delay time a 1,II Can be freely selected as appropriate, whereby for a time period or phase t I And t II Corresponding values are obtained.
During emergency braking, the time-dependent variable v is used 1 、v 2 、a 1 And d 2 The remaining time Δ t can be calculated for each time t I Until the head car 1 has to decelerate its deceleration from a 1,max Down to a 1,II Until now.
In summary, therefore, a method is proposed in which, once emergency braking is activated by any motor vehicle in a fleet, the latter motor vehicle and in particular the motor vehicle immediately behind the fleet is informed about this via a V2V communication. All following vehicles then also assume emergency braking. In this case, each motor vehicle is first braked at its maximum possible deceleration.
By means of V2V communication, the vehicle which is braking in emergency continuously transmits its instantaneous deceleration, speed and distance from the respective preceding vehicle to the other vehicles of the fleet which are braking in emergency. Using these values, the vehicle respectively traveling ahead can calculate, with the aid of the two variants of the method described above, at which deceleration it should be braked maximally to avoid a collision with the vehicle immediately behind.
List of reference numerals
1. Head vehicle, first vehicle
2. Second motor vehicle
4. Third motor vehicle
6. Fourth motor vehicle
8. Fifth motor vehicle
10. The sixth motor vehicle
14. Inter-vehicle communication
16. Obstacle object
100. A fleet of vehicles.

Claims (14)

1. A method for controlling a vehicle group (100) having a first motor vehicle (1) traveling ahead and at least one second motor vehicle (2) directly following the first motor vehicle (1) traveling ahead in an electronically coupled manner, in which method the motor vehicles (1, 2) are at least temporarily at a longitudinal distance (d) that is predeterminable and remains constant from one another based on a predeterminable overall operating strategy associated with the vehicle group (100) 2 ) Moving along a driving route, wherein the first motor vehicle (1) and the second motor vehicle (2) exchange data with each other by means of inter-vehicle communication (V2V), the data relating to at least their instantaneous longitudinal deceleration (a) 1 ,a 2 ) And at least one sensor (d) representing the instantaneous longitudinal distance (d) between the second motor vehicle (2) and the first motor vehicle (1) 2 ) Said method comprising at least the following steps:
a) When the first motor vehicle (1) passes through the emergency brake triggered by the driver and/or automatically in the first motor vehicle (1), the first motor vehicle (1) triggers the emergency brake from the triggering moment (t) of the emergency brake 0 ) When braking is initiated, the emergency braking of the first motor vehicle (1) is initiated from the triggering time (t) 0 ) Starting with a first deceleration value (a) which is the maximum possible for the first motor vehicle (1) 1,max ) Is performed with a longitudinal deceleration, wherein,
b) The triggering of the emergency braking in the first motor vehicle (1) is communicated to the second motor vehicle (2) by means of the inter-vehicle communication (V2V), whereupon the triggering point in time (t) is substantially detected in the second motor vehicle (2) 0 ) Triggering a second deceleration value (a) having the greatest possible value for the second motor vehicle (2) 2,max ) Is braked in a longitudinal direction with a deceleration andand is provided with
c) If the data exchanged between the first motor vehicle (1) and the second motor vehicle (2) is based on 0 ) Late first time (t) 1 ) Identifying a longitudinal spacing (d) representative of said longitudinal spacing 2 ) Is changed during continuous emergency braking such that a longitudinal deceleration (a) of the first motor vehicle (1) is reduced in the event of a risk of the second motor vehicle (2) colliding with the first motor vehicle (1) 1 ) At least to a first deceleration value (a) greater in magnitude than said maximum possible in a stepwise manner 1,max ) Small, limited deceleration value (a) 1,lim ;a 1,II ) In that the second motor vehicle (2) is brought into contact with the first motor vehicle (1) neither during the emergency braking nor in a state in which the first motor vehicle (1) and the second motor vehicle (2) are braked to a standstill.
2. Method according to claim 1, characterized in that the limited deceleration value (a) of the first motor vehicle (1) 1,lim ) From the first time (t) 1 ) Are adapted continuously according to time (t).
3. Method according to claim 2, characterized in that the limited deceleration value (a) of the first motor vehicle (1) 1,lim ) From the first time (t) 1 ) According to the minimum allowable longitudinal spacing (d) 2,min ) And is continuously adapted at least according to the following quantities detected and varying over time (t): the speed (v) of the second motor vehicle (2) 2 ) And longitudinal deceleration (a) 2 ) Speed (v) of the first motor vehicle 1 ) And a longitudinal distance (d) between the first motor vehicle (1) and the second motor vehicle (2) 2 )。
4. Method according to claim 2 or 3, characterized in that the limited deceleration value (a) of the first motor vehicle (1) 1,lim ) From the first time (t) 1 ) Adapted as specified below:
Figure FDA0003751873820000021
wherein,
a 1,lim is the limited deceleration value of the first vehicle,
s 2 is the braking distance of the second motor vehicle,
d 2 is the longitudinal spacing between the first vehicle and the second vehicle,
d 2,min is the minimum allowable longitudinal spacing between the first vehicle and the second vehicle,
v 1 is the speed of the first motor vehicle,
wherein the braking distance s of the second motor vehicle (2) 2 As specified below:
Figure FDA0003751873820000031
wherein, a 2 Is the deceleration of the second motor vehicle, v 2 Is the speed of the second vehicle.
5. The method of claim 1,
a) At a time (t) from the triggering 0 ) Starting and extending to said first time (t) 1 ) First time period (t) I ) During which the first motor vehicle (1) is operating at the maximum possible first deceleration value (a) 1,max ) The brake is carried out by the brake device,
b) At least one from the first time (t) 1 ) At a second time (t) 2 ) Second time period of termination (t) II ) During which the longitudinal deceleration of the first motor vehicle (1) is reduced to the limited deceleration value (a) 1,II ) Wherein the first motor vehicle (1) is operated at the limited deceleration value (a) 1,II ) Decelerating until said second moment (t) 2 ) A first speed (v) of the first motor vehicle (1) 1 ) Relative to standA second speed (v) of the second motor vehicle (2) 2 ) Is substantially equally large, and then
c) At a time from the second time (t) 2 ) At the third time (t) 3 ) A third time period of termination (t) III ) During this third time, a braking-to-standstill state of the first motor vehicle (1) and the second motor vehicle (2) is reached, the first motor vehicle (1) having a second deceleration value (a) which is the greatest possible for the second motor vehicle (2) 2,max ) And (5) braking.
6. Method according to claim 5, characterized in that the second motor vehicle (2) is in the first time period (t) I ) A second time period (t) II ) And a third time period (t) III ) At said maximum possible second deceleration value (a) 2,max ) And (5) braking.
7. Method according to claim 5 or 6, characterized in that during at least one second time period (t) II ) During which said limited deceleration value (a) 1,II ) Is smaller in magnitude than said maximum possible second deceleration value (a) 2,max )。
8. The method according to one of claims 1 to 3, characterized in that the first motor vehicle (1) traveling ahead automatically adopts an emergency braking process by means of an actuation of a brake actuation device by the driver and/or by an automatic driving device of the first motor vehicle (1) traveling ahead as a function of the detected environmental data.
9. Method according to any one of claims 1 to 3, characterized in that the longitudinal distance (d) between the first preceding vehicle (1) and the second following vehicle (2) is adjusted 2 ) And/or relative speed and/or relative acceleration as the at least one representative longitudinal spacing (d) 2 ) The parameter (c) of (d).
10. Method according to one of claims 1 to 3, characterized in that, in addition to the activation of the braking device, in the first motor vehicle (1) and in the second motor vehicle (2) during emergency braking, a regulating signal for reducing the drive power of the drive machine of the first motor vehicle (1) and of the second motor vehicle (2) is generated in each case.
11. A method according to any one of claims 1 to 3, characterized in that the first motor vehicle (1) travelling ahead is formed by the head vehicle of the platoon or by a motor vehicle directly or indirectly following the head vehicle in the platoon (100).
12. A method according to any one of claims 1 to 3, characterized in that emergency braking is triggered by the detection of an obstacle by the previously travelling first motor vehicle (1) in front of it.
13. The method according to any one of claims 1 to 3, characterized in that it is carried out if at the first moment (t) on the basis of data exchanged between the first motor vehicle (1) and the second motor vehicle (2) 1 ) Identifying a representative longitudinal spacing (d) 2 ) Is not changed or is not exposed to the risk of the second motor vehicle (2) colliding with the first motor vehicle (1) during the continuous emergency braking, the emergency braking of the first motor vehicle (1) is completely at its maximum possible first deceleration value (a) 1,max ) And (5) implementing.
14. Method according to any one of claims 1 to 3, characterized in that the second, following motor vehicle is braked throughout the emergency with its maximum possible second deceleration value (a) 2,max ) Braking to decelerate longitudinally.
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