Method for determining a driving maneuver of a vehicle

Abstract

The invention relates to a method for determining a driving maneuver of a vehicle, in particular a method for determining a target speed trajectory, characterized in that a distance of a calculation point to the vehicle is corrected by a distance traveled, wherein a driving maneuver variable is calculated for the calculation point.

Description

State of the art

[0001] Various methods exist for determining driving maneuvers and operating strategies for vehicles. Known hybrid operating strategies are adapted to hybrid powertrain topologies and essentially consider the battery charging process under the influence of the torque distribution between the combustion engine and the electric motor.

[0002] A sailing assistance function maximizes the duration of the sailing state by estimating how long no propulsive torque will be required from the combustion engine. This is partly achieved using predictive data.

[0003] Driving strategy functions calculate speed trajectories designed to optimize comfort. Fuel efficiency is not taken into account.

[0004] Well-known functions that react to vehicles ahead, such as ACC, use information from the surroundings detection to predict the behavior of the vehicle ahead.

[0005] Since the functions known from the state of the art were each developed specifically for their special application and partly influence the same manipulated variable (e.g. target speed), their combination in a vehicle represents a challenge. For example, a coasting assistant would specify the state "coasting" (i.e. essentially decoupling and switching off the internal combustion engine) as the target value, but a cruise control function could simultaneously demand acceleration in order to maintain a preset desired speed.

[0006] Functions that control a target speed depending on a route topology use an optimization algorithm whose solution space is defined as a speed band. However, fixed speed bands are unsuitable for considering non-stationary boundary conditions, such as the speed of a vehicle ahead.

[0007] An optimization algorithm can be used for energy-efficient planning of vehicle maneuvers, such as determining a target speed trajectory. However, calculating an optimal target speed for a future point in time requires a finite amount of computing time, so the calculation result is only available with a time delay. This time delay can result in the vehicle no longer being at the location used as the actual position of the vehicle for the calculation when the result is available. This can lead to inaccuracies in the planning of driving maneuvers, particularly in the determination of target speed trajectories. Disclosure of the invention

[0008] According to the invention, a method for determining a driving maneuver of a vehicle, in particular a method for determining a target speed trajectory, is provided, in which a distance of a calculation point from the vehicle is corrected by a distance traveled. A calculation point is in particular a point along a planned route for which a driving maneuver variable, such as an optimal target speed or a distribution factor of a hybrid drive system, is determined. The driving maneuver variable thus characterizes an optimal state of the vehicle at the calculation point. If the driving maneuver variable is a target speed, the set of all driving maneuver variables along the planned route results in the target speed trajectory.

[0009] It is particularly advantageous if the calculation time for calculating the driving maneuver variable is recorded. The calculation time is the time required to calculate the driving maneuver variable.

[0010] It is particularly advantageous to derive a distance traveled by the vehicle during the calculation of the maneuver variable from the calculation time, and an uncorrected output distance to correct the distance traveled by the vehicle during the calculation time. The output distance is understood to be the distance along the route that a calculation point belonging to the calculated maneuver variable lies in front of the vehicle.

[0011] In a simplified example, the driving maneuver variable may correspond to a target speed of 50 km / h at a calculation point 400 meters in front of the vehicle. However, if the calculation takes one second, during which the vehicle is moving at a speed of 72 km / h, the vehicle will have traveled a distance of 20 meters during the calculation, which is why the output distance is corrected such that the optimal speed of 50 km / h is now assigned to a point 380 meters from the vehicle. In this case, the corrected output distance is 380 meters, while the uncorrected output distance corresponds to 400 meters. Using the corrected output distance for each driving maneuver variable therefore results in a significantly optimized target speed trajectory.

[0012] It is particularly advantageous to determine the distance traveled during the calculation of the driving maneuver variable by integrating the speeds traveled by the vehicle during the calculation period. The calculation period does not have to be known directly; rather, it is sufficient to start an integrator together with the calculation of the driving maneuver variable and to stop it again when the driving maneuver variable has been fully calculated. In this exemplary embodiment, the calculation period therefore only indirectly influences the determination of the distance traveled. Alternatively, the distance traveled during the calculation of the driving maneuver variable can be determined using a timestamp that marks the start of the calculation, a timestamp that marks the end of the calculation of the driving maneuver variable, and a vehicle speed assumed to be constant.

[0013] The method according to the invention is advantageously used in an optimizer or optimization module.

[0014] In an advantageous further development, the optimizer determines an optimal driving maneuver, in particular an optimal target speed, in particular an optimal target speed trajectory of the vehicle, based on the solution space.

[0015] In an advantageous development, when determining the driving maneuver or the target speed or the target speed trajectory, the optimizer takes into account, in particular, fuel consumption, absolute acceleration, a deviation from an average speed, and a deviation from an average acceleration. Furthermore, a predicted travel time and, in the case of a vehicle with a deactivatable internal combustion engine (for example, in the case of a correspondingly configured hybrid vehicle), a number of start-up processes of the internal combustion engine are taken into account. In an advantageous development of the method according to the invention, the optimizer also takes into account a distance to a vehicle traveling ahead, for example by using a penalty function that assigns a penalty value to each temporal distance to the vehicle traveling ahead.

[0016] The solution space is preferably determined using the method described below: Since important elements in road traffic, such as vehicles driving ahead, cannot be represented by a speed band, the solution space for a target speed of a vehicle is extended by a temporal dimension.

[0017] In the temporal dimension, a t-band is advantageously defined, i.e., a band of functions that assign a (required) time to a distance traveled or a location. The t-band is obtained by integrating a v-band, which is defined by functions that assign a speed to a distance or position. The v-band can be determined using methods known from the state of the art and, in particular, takes into account a route topology.

[0018] Advantageously, a preceding vehicle can be taken into account by limiting the t-band with a predicted spatial-time trajectory of the preceding vehicle. In other words, the t-band can be limited such that the implementation of the target vehicle speed cannot lead to a collision with the preceding vehicle. In a particularly advantageous embodiment, the spatial-time trajectory of the preceding vehicle is determined by integrating a predicted speed trajectory of the preceding vehicle. In a further preferred embodiment, the speed trajectory of the preceding vehicle is determined using a combination of sensor data, in particular radar data, and an electronic horizon.The electronic horizon can, for example, take into account that the vehicle in front is subject to a local speed limit or that the vehicle in front is likely to drive at a reduced speed on steep inclines or in tight bends.

[0019] The determination of the solution space advantageously includes the following steps: The speed of a preceding vehicle is predicted by assuming its current acceleration to be constant at the prediction time, based on its current speed. This yields a speed trajectory of the preceding vehicle. By integration, a position-time trajectory of the preceding vehicle is determined from the speed trajectory of the preceding vehicle.

[0020] The solution space is adapted to the current speed of the vehicle (ego vehicle) by choosing a beginning of the speed band (i.e. v-band, i.e. the band between the upper and lower raw speed limit) such that it includes the current speed of the vehicle, advantageously in particular such that it corresponds to the current speed of the vehicle.

[0021] A lower raw time limit is determined by integration from the upper raw speed limit.

[0022] An upper time limit is determined by integrating the lower speed raw limit.

[0023] Based on the location-time trajectory of the preceding vehicle, the lower time limit is modified, in particular partially raised, in such a way that the lower time limit thus obtained is above the location-time trajectory of the preceding vehicle.

[0024] A solution space is defined from the upper time limit and the lower time limit, which is passed to the optimizer.

[0025] An embodiment of the present invention is explained in more detail below with reference to the accompanying drawings. Short description of the drawings Fig. 1 shows a sketchy signal flow to illustrate an embodiment of the method according to the invention; Fig. 2 a schematic representation of an upper and lower speed limit; Fig. 3 a schematic representation of an upper and lower time limit according to an advantageous development of the method according to the invention; Fig. 4 shows a schematic sequence of an embodiment of the method according to the invention. Embodiments of the invention

[0026] Fig. 1 shows a schematic signal flow to illustrate an embodiment of the method according to the invention. A powertrain management module (10) provides a current vehicle state and transmits it to a solution space module (13) and an optimization module (14). A horizon module (11) provides an electronic horizon and transmits it to the solution space module (13). The electronic horizon includes, in particular, a gradient of a road section ahead as well as an upper and a lower speed limit. Optionally, the electronic horizon can additionally include a curve radius. An environment module (12) provides information about a vehicle traveling ahead and transmits it to the solution space module (13) and an implementation module (16). The information about the vehicle traveling ahead can include, in particular, its speed and the distance from the vehicle (ego vehicle).The solution space module (13) processes the information provided to it and derives an upper and a lower speed limit and / or an upper and lower time limit therefrom. It transmits these, along with the gradient of the upcoming route section, to the optimization module (14). A vehicle state estimator (15) estimates the current vehicle state and transmits this to the optimization module (14) and the solution space module (13). The current vehicle state is advantageously taken into account when deriving the upper and lower speed limits, as well as the upper and lower time limits. The optimization module (14) can advantageously comprise a vehicle model. The optimization module (14) determines an optimized target speed, in particular a target speed trajectory for the vehicle, and transmits this to the implementation module (16).The implementation module implements the target speed trajectory by appropriately controlling the corresponding actuators of the vehicle, taking into account the information about the vehicle in front, provided by the environment module (12).

[0027] In particular, information about the preceding vehicle can overwrite the implementation of the target speed trajectory for safety reasons, for example, if the preceding vehicle brakes sharply and its deceleration is not reflected quickly enough by the signal chain from the solution space module (13) and the optimization module (14). Alternatively, the implementation module (16) can display the target speed trajectory to a driver of the vehicle (ego vehicle), who then manually implements the target speed trajectory. This is particularly advantageous if the implementation module does not guarantee direct access to the required actuators.

[0028] Fig. Figure 2 shows a schematic representation of an upper (43) and lower (42) raw speed limit, as can be determined, for example, using methods known from the prior art. A position axis (40) indicates the location of the vehicle. A speed axis (41) assigns an upper and a lower raw speed value to each point on the position axis (40), so that a representation of the upper (43) and lower (42) raw speed limits is obtained from all upper and lower raw speed values. The upper and lower raw speed limits define, for example, a speed solution space for an optimization algorithm.

[0029] Fig. 3 shows a schematic representation of an upper (52) and lower (55) time limit according to one aspect of the method according to the invention. A position axis (50) represents the abscissa, a time axis (51) the ordinate. An upper time limit (52) can be obtained, for example, by integrating the lower raw speed limit (42). A lower raw time limit (53) can be obtained by integrating the upper raw speed limit (43). A position-time trajectory of a preceding vehicle (54) assigns to each location a predicted time at which the preceding vehicle will be located at this location. The lower raw time limit (53) intersects the position-time trajectory of the preceding vehicle (54) in the illustrated example, which is why the lower raw time limit (53) is modified to obtain the lower time limit (55).If necessary, the lower time limit (53) is raised so that the lower time limit (55) is always above the position-time trajectory of the preceding vehicle (54). This can advantageously take into account a safety distance to the preceding vehicle, which the vehicle (ego vehicle) should not exceed. The upper time limit (52) and the lower time limit (55) define a solution space for an optimizer.

[0030] Fig. Figure 4 shows a schematic flow of an exemplary embodiment of the method according to the invention. In step 100, a calculation of a driving maneuver variable, in particular a target speed, is started for a point at a given distance along the planned route in front of the vehicle. The distance to this point represents the output distance. At the same time, an integrator is started, which integrates the vehicle's speed until it is stopped again.

[0031] Step 110 is then carried out.

[0032] In step 110, the calculation of the driving maneuver variable, in particular the target speed, started in step 100, ends. The integrator, also started in step 100, is stopped, and the distance traveled during the calculation of the driving maneuver variable is determined. Step 120 is then executed.

[0033] In step 120, the driving maneuver variable obtained in step 110 is assigned to a corrected output distance by subtracting the distance traveled during the calculation of the driving maneuver variable determined in step 110 from the output distance. Step 130 is then performed.

[0034] In step 130, the corrected output distance is output together with the driving maneuver variable, in particular the target speed.

[0035] Steps 100 to 130 are performed iteratively for various output distances, resulting in a plurality of driving maneuver variables, particularly target speeds. The plurality of driving maneuver variables, together with the corresponding corrected output distances, are combined to form a trajectory. If the driving maneuver variable is the target speed, a target speed trajectory is determined.

[0036] Steps 100 to 130 are preferably carried out in the optimization module (14).

Claims

[1] Method for determining a driving maneuver of a vehicle, in particular method for determining a target speed trajectory, characterized by that a distance of a calculation point to the vehicle is corrected by a distance traveled, whereby a driving maneuver variable is calculated for the calculation point. [2] Method according to claim 1, characterized by that the calculation time required to calculate the driving maneuver size is determined. [3] Method according to claim 2, characterized by that the calculation time is determined using timestamps. [4] Method according to claim 2 or 3, characterized by that the distance travelled is determined from the calculation time. [5] Method according to claim 1, characterized by that the speed of the vehicle is integrated during the calculation of the driving maneuver variable in order to determine the distance traveled. [6] Device arranged to carry out the method according to one of claims 1 to 5. [7] Computer program which causes a computing unit to carry out the method according to one of claims 1 to 5 when the computer program is executed by the computing unit. [8] Storage medium on which the computer program according to claim 7 is stored.

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