Method and device for operating a vehicle

Abstract

The invention relates to a method for operating a vehicle (1), wherein a speed limit (B) is provided by a navigation device (4) before the vehicle reaches a position (POS) of the speed limit (B). At a vehicle position (FPOS) located in the direction of travel of the vehicle (1) before the position (POS) of the speed limit (B), a distance (d) between the vehicle (1) and the position (POS) is determined. Depending on the actual speed (v) of the vehicle (1), an actual value of the kinetic energy of the vehicle (1) is determined at this vehicle position (FPOS). Furthermore, depending on a target speed of the vehicle (1) specified by the speed limit (B), which is lower than the actual speed (v), a target value of the kinetic energy of the vehicle (1) that it should possess at the position (POS) of the speed limit (B) is determined.Depending on the determined distance (d), a braking torque of at least one drive unit (5) of the vehicle (1) is controlled or regulated, while simultaneously minimizing the use of a friction-based service brake, such that the vehicle (1) has the target value of kinetic energy at the position (POS) of the speed limit (B). The invention further relates to a device (2) for operating a vehicle (1).

Description

[0001] The invention relates to a method for operating a vehicle according to the preamble of claim 1.

[0002] The invention further relates to a device for operating a vehicle according to the preamble of claim 7.

[0003] From DE 10 2016 108 619 A1, a vehicle speed limiter system is known that is installed in a vehicle. The vehicle speed limiter system comprises: - a detection unit configured to extract a speed limit value for a road on which the vehicle is traveling from an image of a traffic sign; - a navigation device in which speed limit values ​​of roads and associated positions are stored, - a setting unit that is configured to set the speed limit value detected by the detection unit or supplied by the navigation device depending on position information of the vehicle; - a limiter unit configured to limit the vehicle's speed based on the speed limit value set by the setting unit; - a receiving unit configured to receive a pedal input on an accelerator pedal of the vehicle; - a calculation unit configured to calculate a parameter dependent on the pedaling input, using the pedaling input obtained by the receiving unit, in a state where the vehicle speed is limited by the limiter unit; and - a display unit configured to display information based on the parameter calculated by the calculation unit in a case where a speed limit value newly detected by the detection unit is greater than the speed limit value previously set by the setting unit before the setting unit sets the newly detected speed limit value.

[0004] The invention is based on the objective of providing a novel method and a novel device for operating a vehicle.

[0005] The problem is solved according to the invention by a method which has the features specified in claim 1 and by a device which has the features specified in claim 7.

[0006] Advantageous embodiments of the invention are the subject of the dependent claims.

[0007] In a method for operating a vehicle, a speed limit on a roadway with an associated position is provided by a navigation device of the vehicle, and a driving speed of the vehicle is automatically set depending on the speed limit by means of a control unit.

[0008] According to the invention, the speed limit is transmitted from the navigation device to the control unit before the vehicle reaches the speed limit sign. The control unit then determines the distance between the vehicle and the speed limit sign at a vehicle position located ahead of the speed limit sign in the direction of travel. Furthermore, the control unit calculates the actual kinetic energy of the vehicle at this position based on its current speed. Additionally, it calculates the target kinetic energy of the vehicle at the speed limit sign based on a lower target speed specified by the speed limit sign.Furthermore, depending on the determined distance, the control unit controls or regulates a braking torque of at least one drive unit of the vehicle while simultaneously minimizing the use of a friction-based service brake, such that the vehicle has the target value of kinetic energy at the speed limit position.

[0009] This method enables the avoidance of dangerous situations caused by sudden braking and potential collisions with following vehicles, for example, during automated driving. Furthermore, by utilizing the speed limit known from the navigation system, and especially compared to optical traffic sign recognition methods, the system allows for early deceleration of the vehicle while simultaneously minimizing the use of the service brakes. By utilizing the braking torque of the drive unit during deceleration, the vehicle's energy consumption can be reduced or optimized, either during coasting (when the drive unit is an internal combustion engine) or during recuperation or generator operation (when the drive unit is an electric machine).At the same time, the minimized use of the service brake reduces brake wear and extends the service brake's lifespan. Furthermore, this method allows existing and future requirements for so-called intelligent speed assistance systems, also known as Intelligent Speed ​​Adaptation or Intelligent Speed ​​Assistance (ISA), to be met in a simple manner.

[0010] According to one possible embodiment of the method, the braking torque of the drive unit required to reach the target value of the kinetic energy is additionally determined as a function of the gradient of the road surface between the vehicle position and the speed limit sign. Both positive and negative gradients (i.e., downhill slopes) are taken into account. By considering the gradient, the values ​​of which are also stored, for example, in digital map data of the navigation system, a particularly precise adjustment of the braking torque can be achieved to reach the target speed at the speed limit sign, while simultaneously maximizing energy savings and minimizing wear on the service brakes.

[0011] According to another possible embodiment of the method, the point in time at which the braking torque of at least one drive unit is activated and / or the time profile of the braking torque until the speed limit is reached is variably specified depending on environmental conditions and / or vehicle parameters. This also enables reliable deceleration of the vehicle to reach the target speed at the speed limit while simultaneously maximizing energy savings and minimizing wear on the service brakes.

[0012] According to another possible embodiment of the procedure, the braking torque is adjusted as follows: - a motor braking function of the drive unit controlled and / or - the drive unit operated in idle mode and / or - the drive unit is decoupled from a gearbox and / or - the drive unit coupled with a gearbox and / or - a gearbox coupled to the drive unit switched to a freewheel or idle position and / or - a driving stage or gear of a transmission coupled to the drive unit is selected and / or - the response behavior of the accelerator pedal has been adjusted.

[0013] This enables simple, reliable, and precise adjustment of the braking torque using mechanisms already present in vehicles. This minimizes the hardware required to implement the process.

[0014] According to another possible embodiment of the method, the actual and target values ​​of the kinetic energy are determined as a function of the vehicle's total weight. This also enables particularly precise adjustment of the braking torque to achieve the target speed at the speed limiter position, while simultaneously maximizing energy savings and minimizing wear on the service brakes. The vehicle's total weight can be determined, for example, by knowing the vehicle's unladen weight, its payload, and the levels of consumables, such as the fuel level. The payload can be determined, for example, using optical detection methods, such as occupant detection, and / or chassis sensors.

[0015] According to another possible embodiment of the method, the position of an accelerator pedal, the state of a control unit coupled to the accelerator pedal, the position of a brake pedal, and / or the state of a control unit coupled to the brake pedal are monitored to adjust the braking torque. This enables safe control.

[0016] A device for operating a vehicle comprises a navigation device which provides a speed limit on a roadway with an associated position, and a control unit which automatically sets the vehicle's speed depending on the speed limit.

[0017] According to the invention, the navigation device transmits the speed limit to the control unit even before the speed limit position is reached. The control unit is designed to - to determine the distance between the vehicle and the speed limit position at a vehicle position located in the direction of travel before the speed limit position, - to determine an actual value of the vehicle's kinetic energy at that vehicle position, depending on the vehicle's actual speed at that vehicle position, - depending on a target speed of the vehicle specified by the speed limit, which is lower than the actual speed, to determine a target value of the kinetic energy of the vehicle that it should have at the position of the speed limit and - depending on the determined distance, to control or regulate a braking torque of at least one drive unit of the vehicle while simultaneously minimizing the use of a friction-based service brake in such a way that the vehicle has the target value of kinetic energy at the position of the speed limit.

[0018] The device enables the avoidance of dangerous situations caused by sudden braking and potential collisions with following vehicles. Furthermore, by utilizing the speed limit known from the navigation system, particularly in comparison to optical traffic sign recognition methods, the vehicle can be braked early while simultaneously minimizing the use of the service brake. By utilizing the braking torque of the drive unit during braking, the vehicle's energy consumption can be reduced or optimized in coasting mode (if the drive unit is an internal combustion engine) or in recuperation or generator mode (if the drive unit is an electric machine). At the same time, the minimized use of the service brake reduces brake wear and extends its service life.Furthermore, the device makes it easy to meet existing and future requirements for so-called intelligent speed assistance systems, also known as Intelligent Speed ​​Adaptation or Intelligent Speed ​​Assistance, or ISA for short.

[0019] Exemplary embodiments of the invention are explained in more detail below with reference to drawings.

[0020] This shows: Fig. 1. Schematic top view of a roadway and a vehicle located on the roadway, Fig. 2. Schematic block diagram of a device for operating a vehicle and Fig. 3 schematically illustrates the sequence of a procedure for operating a vehicle.

[0021] Corresponding parts are marked with the same reference symbols in all figures.

[0022] In Fig. Figure 1 shows a top view of a roadway FB and a vehicle 1 located on the roadway FB at a vehicle position FPOS. The vehicle 1 is moving at a speed v at vehicle position FPOS.

[0023] In the direction of travel ahead of vehicle 1, at position POS, there is a traffic sign Z indicating a speed limit B. A distance d is formed between position POS and the vehicle position FPOS.

[0024] Fig. Figure 2 shows a block diagram of a possible embodiment of a device 2 for operating the vehicle 1 according to Fig. 1. The device 2 comprises a control unit 3, a navigation device 4 and a drive unit 5. The drive unit 5 is designed to generate propulsion for the vehicle 1 and is designed, for example, as an electric machine or an internal combustion engine.

[0025] The drive unit 5 is designed to be controlled by the control unit 3 and to generate a braking torque in overrun mode (when configured as an internal combustion engine) or in recuperation or generator mode (when configured as an electric machine), by means of which the vehicle 1 can be braked. In overrun mode, fuel consumption is generally minimized. In recuperation or generator mode, the drive unit 5 converts kinetic energy into electrical energy.

[0026] The navigation device 4 contains speed limits B for lanes or lane sections, along with their corresponding position POS, stored in a digital road map. The navigation device 4 is configured to provide the speed limits B and their corresponding position POS to the control unit 3. In particular, the navigation device 4 is configured to receive updates via so-called over-the-air updates.

[0027] In Fig. 3 is a sequence of a possible embodiment of a method for operating the vehicle 1 according to Fig. 1 using the device 2 according to Fig. 2 shown.

[0028] Is vehicle 1 moving according to Fig.As vehicle 1 approaches traffic sign Z at its current speed v, it is intended that upon reaching traffic sign Z, the vehicle 1 will have a target speed corresponding to the speed limit B, which is lower than the current speed v. For example, vehicle 1 will be operating in automated driving mode, such as with cruise control activated, or in highly automated or autonomous driving mode.

[0029] In one possible configuration of the procedure, knowledge of - a position of an accelerator pedal and / or - a state of a control unit 3 coupled to the accelerator pedal and / or - a position of a brake pedal and / or - a state of a control unit 3 coupled to the brake pedal and / or - the actual speed v of vehicle 1 and / or - the target speed specified by speed limit B and / or - the vehicle position FPOS and / or - the position POS of the speed limit B is required. The aforementioned information is determined, for example, by means of the vehicle's own sensors and / or is stored in the navigation device 4.

[0030] To reduce the actual speed v to the target speed, before starting the procedure, it is first checked whether the ignition of vehicle 1 is activated.

[0031] If this is the case, a process step S1 is executed. Because the vehicle 1, or rather the control unit 3, already knows the speed limit B and its position POS from the navigation device 4 well before reaching position POS, it expects an incoming speed limit signal at position POS. In process step S1, the control unit 3 then determines the distance d between the vehicle 1 and the speed limit B position POS using the vehicle position FPOS, which is located in the direction of travel of the vehicle 1 before position POS.

[0032] Subsequently, in a further process step S2, the control unit 3 determines an actual value of the kinetic energy of vehicle 1 as a function of the actual speed v of vehicle 1 at vehicle position FPOS. Furthermore, the control unit 3 determines a target value of the kinetic energy that vehicle 1 should possess at position POS of the speed limit B, as a function of the target speed of vehicle 1 specified by the speed limit B, which is lower than the actual speed v.

[0033] In this process, the kinetic energy E Kin for example, according to each EKin=12mv2 determined where m is the physical mass of vehicle 1 and v is the speed of vehicle 1.

[0034] From the law of conservation of energy, it then follows that Δd=m2F(vFinal2−vInitial2) a ratio between a distance traveled, that is, the distance d, of vehicle 1, where the journey is made at an initial speed v Initial began and with a final velocity v Final The force F in this case is a frictional force and is given by F = µN. The value µ is the kinetic coefficient of friction, which varies depending on whether the tires are new or used and whether the road surface is dry or wet. For example, µ is specified with an average value of 0.8 or is estimated using weather and / or tire sensors. N is the acceleration due to gravity and is 9.81 m / s². 2 .

[0035] This means that in process step S2, the kinetic energy of the vehicle 1 at the vehicle position FPOS and the position POS of the speed limit B is determined, for example estimated, where it is known that the vehicle 1 must slow down within the distance d due to the speed limit B and is therefore braked by means of a service brake and / or by means of the braking torque of the drive unit 5 and / or by utilizing the friction between tires and the road surface and / or by an air resistance of the vehicle 1.

[0036] Subsequently, in a further process step S3, a theoretical distance is determined which the vehicle 1 can cover in a kinetic mode of the drive unit 5 without additional energy consumption, i.e. fuel consumption or electricity consumption, in order to reach the target speed specified by the speed limit B at position POS.

[0037] In the kinetic mode of the drive unit 5, depending on its design, it functions as either an internal combustion engine or an electric machine. - a motor braking function, i.e., a coasting operation or recuperation or generator operation, controlled by the drive unit 5 and / or - the drive unit 5 operated in idle mode and / or - the drive unit 5 is decoupled from a gearbox and / or - the drive unit 5 coupled with a gearbox and / or - a gearbox coupled to the drive unit 5 is switched into a freewheel or idle mode and / or - a driving stage or gear of a transmission coupled to the drive unit 5 is set and / or - the response behavior of the accelerator pedal has been adjusted.

[0038] In kinetic mode, the energy consumption of drive unit 5 is minimized.

[0039] Depending on the current distance d of vehicle 1 to the position POS of the speed limit B and the theoretical distance already estimated in process step S3, a branch X1 then checks whether the accelerator pedal or the brake pedal needs to be operated to reach the target speed at position POS.

[0040] If this is not the case, represented by a "no" branch N, the kinetic mode of the drive unit 5 is activated in a further process step S4. In this step, the braking torque of the drive unit 5 is controlled or regulated by the control unit 3, depending on the determined distance d, while simultaneously minimizing the use of the friction-based service brake, such that the vehicle 1 has the target value of kinetic energy at position POS of the speed limit B. This minimizes wear on the service brake and the energy consumption of the drive unit 5.

[0041] In particular, if the accelerator pedal needs to be actuated to reach the target speed at position POS, represented by a yes branch J, the kinetic mode of the drive unit 5 is deactivated in a further process step S5.

[0042] This means that if the distances d or the theoretical distance are exceeded, the control unit 3 can control the actual speed v of the vehicle 1 by pressing the accelerator pedal or influencing its control unit 3. Reference symbol list 1 vehicle 2 Device 3 Control unit 4 Navigation device 5 Drive unit B Speed ​​limit d distance FB Roadway FPOS vehicle position J Ja branch N No branch POS Position S1 to S5 process step v Actual speed X1 branch Z Traffic sign QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] DE 10 2016 108 619 A1

[0003]

Claims

[1] Method for operating a vehicle (1), wherein - a speed limit (B) on a roadway (FB) with an associated position (POS) is provided by a navigation device (4) of the vehicle (1), - by means of a control unit (3) a driving speed of the vehicle (1) is automatically set depending on the speed limit (B), characterized by , that - the speed limit (B) is transmitted from the navigation device (4) to the control unit (3) before the position (POS) of the speed limit (B) is reached, - by means of the control unit (3) at a vehicle position (FPOS) located in the direction of travel of the vehicle (1) in front of the position (POS) of the speed limit (B), a distance (d) between the vehicle (1) and the position (POS) of the speed limit (B) is determined, - an actual value of a kinetic energy of the vehicle (1) is determined by means of the control unit (3) as a function of an actual speed (v) of the vehicle (1) at this vehicle position (FPOS), - by means of the control unit (3) as a function of a target speed of the vehicle (1) specified by the speed limit (B), which is lower than the actual speed (v), a target value of a kinetic energy of the vehicle (1) which it should have at the position (POS) of the speed limit (B) is determined and - by means of the control unit (3) as a function of the determined distance (d), a braking torque of at least one drive unit (5) of the vehicle (1) is controlled or regulated while simultaneously minimizing the use of a friction-based service brake in such a way that the vehicle (1) has the desired value of the kinetic energy at the position (POS) of the speed limit (B). [2] Method according to claim 1, characterized by that the braking torque of the drive unit (5) required to achieve the target value of the kinetic energy is additionally determined as a function of a gradient of the roadway (FB) existing between the vehicle position (FPOS) and the position (POS) of the speed limit (B). [3] Method according to claim 1 or 2, characterized by that a time of commencement of activation of the braking torque of the at least one drive unit (5) and / or a temporal progression of the braking torque until the position (POS) of the speed limit (B) is reached are / is variably predetermined depending on ambient conditions and / or vehicle parameters. [4] Method according to one of the preceding claims, characterized by that to adjust the braking torque - an engine braking function of the drive unit (5) is controlled and / or - the drive unit (5) is operated at idle and / or - the drive unit (5) is decoupled from a transmission and / or - the drive unit (5) is coupled to a gearbox and / or - a transmission coupled to the drive unit (5) is switched to freewheel or neutral and / or - a driving position or a gear of a transmission coupled to the drive unit (5) is set and / or - the response behavior of an accelerator pedal is adjusted. [5] Method according to one of the preceding claims, characterized by that the actual value and the target value of the kinetic energy are determined as a function of a total weight of the vehicle (1). [6] Method according to one of the preceding claims, characterized by that to adjust the braking torque - a position of an accelerator pedal and / or - a state of a control unit (3) coupled to the accelerator pedal and / or - a position of a brake pedal and / or - a state of a control unit (3) coupled to the brake pedal is / is monitored. [7] Device (2) for operating a vehicle (1) with - a navigation device (4) which provides a speed limit (B) on a roadway (FB) with an associated position (POS), and - a control unit (3) which automatically sets a driving speed of the vehicle (1) depending on the speed limit (B), characterized by , that - the navigation device (4) transmits the speed limit (B) to the control unit (3) before the position (POS) of the speed limit (B) is reached, - the control unit (3) is designed - to determine a distance (d) between the vehicle (1) and the position (POS) of the speed limit (B) at a vehicle position (FPOS) located in the direction of travel of the vehicle (1) before the position (POS) of the speed limit (B), - to determine an actual value of a kinetic energy of the vehicle (1) at the vehicle position (FPOS) as a function of an actual speed (v) of the vehicle (1) at this vehicle position (FPOS), - to determine, as a function of a target speed of the vehicle (1) specified by the speed limit (B), which is lower than the actual speed (v), a target value of a kinetic energy of the vehicle (1) which it should have at the position (POS) of the speed limit (B), and - depending on the determined distance (d), to control or regulate a braking torque of at least one drive unit (5) of the vehicle (1) while simultaneously minimizing the use of a friction-based service brake in such a way that the vehicle (1) has the desired value of the kinetic energy at the position (POS) of the speed limit (B).

Images