Method and device for determining a speed profile for a vehicle along a path for the vehicle

Abstract

The present invention relates to a method and a device for determining a speed profile for a vehicle along a path, the method comprising: a step for determining a current remaining distance (sxTar) along the path for reaching a predefined stopping position for the vehicle, a step for determining a current target speed (vxref) for the vehicle as a function of the remaining distance (sxTar) based on at least a first PT1 element (40) and a second PT1 element (42), wherein a first signal (S1) representing the current remaining distance (sxTar) between the vehicle and the stopping position is fed into an input of the first PT1 element (40), an output of the first PT1 element (40) is connected to an input of the second PT1 element (42), an output of the second PT1 element (42) is connected to an input of a first integrator (50),an output of the first integrator (50) is connected in a negative feedback manner to the input of the second PT1 element (42), the output of the first integrator (50) is connected to an input of a second integrator (52), an output of the second integrator (52) is connected in a negative feedback manner to the input of the first PT1 element (40), and a second signal (S2), which is output at the output of the first integrator (50), is used to set the current target speed (vxRef).

Description

State of the art

[0001] The present invention relates to a method and a device for determining a speed profile for a vehicle along a path for the vehicle.

[0002] Methods and devices are known from the prior art that implement a so-called trajectory planner for vehicles. Such a trajectory planner preferably determines a collision-free path for the vehicle between a current position and a target position for the vehicle as a function of time. Such a target position can, for example, be a parking position for the vehicle.

[0003] The trajectory often results from the solution of an optimization problem whose solution cannot be directly computed analytically but is determined iteratively. Different approaches exist for representing the trajectory and its parameters.

[0004] One possibility is to use a fifth- or seventh-degree polynomial for the vehicle's longitudinal motion, where such a polynomial is defined by its boundary conditions (e.g., a desired comfort level, an end time, etc.). Various combinations are evaluated, and the combination with the best suitability for a particular driving maneuver is selected.

[0005] The optimization approach described above is pursued in the following works, among others: Werling, M. 2011. "A New Concept for Trajectory Generation and Stabilization in Time-Critical Traffic Scenarios," Karlsruhe: KIT Scientific Publishing. DOI: https: / / doi.org / 10.5445 / KSP / 1000021738 Rathgeber, C.; Winkler, F.; Müller, S.: “Collision-free longitudinal and lateral trajectory planning taking vehicle-specific potentials into account,” In: at-Automatisierungstechnik 64 (2016), No. 1, pp. 61-76 Disclosure of the invention

[0006] According to a first aspect of the present invention, a method is proposed for determining a speed profile (or a speed curve) for a vehicle along a path for the vehicle, along which the vehicle is to be moved between a current position of the vehicle and a predefined stopping position for the vehicle to reach the stopping position.

[0007] It should be noted that the path can be determined, among other things, by means of a component known from the prior art for determining a path suitable for a respective driving maneuver (e.g. by a parking assistant, etc.) and can be provided to the method according to the invention.

[0008] The vehicle is, for example, a road vehicle such as a car, a van, a truck, a bus or a different vehicle.

[0009] The method according to the invention described below is advantageously carried out by means of an evaluation unit which is designed, for example, as an ASIC, FPGA, processor, digital signal processor, microcontroller, or the like and is preferably a component of the vehicle and / or a component of a component different from the vehicle (e.g., a cloud server, etc.).

[0010] In a first step of the method according to the invention, a current remaining distance along the path intended for the vehicle to reach the stopping position for the vehicle is determined.

[0011] The current remaining distance is calculated, for example, by the trajectory planner and / or a logical and / or physical component that deviates therefrom and provided to the method according to the invention. The remaining distance can be calculated, for example, based on the vehicle's sensor systems (camera, lidar, radar, ultrasound, etc.) on a vehicle control unit and subsequently provided, for example, to a vehicle brake control unit, on which the method described here can be executed.

[0012] Alternatively or additionally, it is possible to determine the current remaining distance on the basis of information about the path and information about the current location of the vehicle itself, wherein the current location of the vehicle can be determined, for example, by means of satellite-based navigation and / or by means of an odometry method known from the prior art, etc.

[0013] In a second step of the method according to the invention, a current target speed for the vehicle is determined as a function of the remaining distance based on at least one first PT1 element (i.e., a first-order delay element) and a second PT1 element (thereby forming a second-order delay element overall), wherein an input signal representing the current remaining distance between the vehicle and the stopping position along the path is fed into an input of the first PT1 element, wherein an output of the first PT1 element is connected to an input of the second PT1 element, wherein an output of the second PT1 element is connected to an input of a first integrator, wherein an output of the first integrator is connected in a negative feedback manner to the input of the second PT1 element (i.e., an output signal of the first integrator is subtracted from an output signal of the first PT1 element and the resulting difference signal is fed into the second PT1 element), wherein the output of the first integrator is connected to an input of a second integrator, wherein an output of the second integrator is connected in a negative feedback manner to the input of the first PT1 element and wherein a second signal which is output at the output of the first integrator is used to set a current target value for a speed of the vehicle. In other words, the current target value for the speed represents a reference variable for a downstream control chain for setting this target value for the vehicle. In the downstream control chain, the required braking and / or acceleration forces for the vehicle can be set accordingly on the basis of the target value for the speed.

[0014] Furthermore, a gain factor of the first PT1 element and a gain factor of the second PT1 element are determined as a function of a desired longitudinal dynamic behavior for the vehicle. Such a desired longitudinal dynamic behavior for the vehicle can be determined, for example, by taking into account the respective vehicle characteristics and / or in accordance with a typical control of the vehicle by a user (e.g., by mapping a typical braking and / or acceleration control by the user, etc.).

[0015] In addition, the steps of the method according to the invention are carried out iteratively until the vehicle reaches the stopping position, whereby target speeds for the vehicle are preferably set at predefined intervals, which can be predetermined by a processing cycle.

[0016] It should be noted that alternatively or in addition to the second signal, a third signal, which is provided at the output of the second integrator and which represents a currently set position of the vehicle along the path, can be incorporated into the downstream control chain as a reference variable.

[0017] The method according to the invention offers, among other advantages, that a desired speed profile for a vehicle during a driving maneuver is mapped using known system elements, and that the vehicle's behavior can thus be described using a differential equation. On this basis, driving behavior can be mapped with particularly low computational effort that essentially corresponds to manual driving and thus essentially corresponds to a familiar or perceived pleasant driving behavior.

[0018] Furthermore, the approach presented here offers the advantage that individual adjustments to the speed profile can be implemented particularly easily and with minimal computational effort. For example, a comfort-oriented or dynamic driving behavior can be easily adjusted according to user preference during a driving maneuver to reach the predefined stopping position.

[0019] The subclaims show preferred developments of the invention.

[0020] In an advantageous embodiment of the present invention, the output of the second PT1 element is connected to the input of the first integrator via a series circuit comprising a third PT1 element and a third integrator, and an output of the third integrator is connected to the input of the third PT1 element in a negative feedback manner. In this way, in addition to the speed and acceleration of the vehicle, which are determined by the above-described use of a second-order delay element based on the remaining distance, a jerk during vehicle control can also be evaluated and / or influenced.

[0021] In a particularly advantageous embodiment of the present invention, the gain factors of the respective PT1 elements differ by at least a factor of four compared to the PT1 element immediately upstream in the processing chain. In other words, the gain factor of the second PT1 element corresponds to at least four times the gain factor of the first PT1 element, and in the case where a third PT1 element is used, the gain factor of the third PT1 element corresponds to at least four times the gain factor of the second PT1 element. In this way, overshoot within the transmission system, which would counteract the goal of achieving a perceived pleasant driving behavior, can be avoided or reduced.

[0022] Preferably, at least some of the output signals generated by the PT1 elements are limited to maximum permissible value ranges before their further processing within the processing chain by means of limiters corresponding to the PT1 elements. These limits are preferably defined individually for each PT1 element used. Particularly advantageously, at least the output signal of the first PT1 element is limited in its value range by means of such a limiter. Further advantageously, a corresponding limiter can also be arranged downstream of the second PT1 element and / or the third PT1 element.

[0023] By means of the limiters described above, a maximum speed for the vehicle is preferably set by the limiter, which can be arranged downstream of the first PT1 element, limiting the output signal of the first PT1 element to a predefined threshold value for a maximum vehicle speed. Alternatively or additionally, the limiter, which can be arranged downstream of the second PT1 element, can limit the output signal of the second PT1 element to a predefined threshold value for a maximum vehicle acceleration and / or to a predefined threshold value for a minimum vehicle acceleration.Alternatively or additionally, the limiter, which can be downstream of the third PT1 element, can limit the output signal of the third PT1 element to a predefined threshold for a maximum jerk of the vehicle and / or to a predefined threshold for a minimum jerk of the vehicle. Furthermore, it is possible to adjust the predefined thresholds of the respective limiters depending on current boundary conditions and / or user preferences.

[0024] The method according to the invention is particularly preferably used to carry out a parking maneuver for the vehicle. Furthermore, it is possible for the stopping position to be a final parking position for the vehicle and / or a position for an intermediate stop for the vehicle during such a parking maneuver. The latter can be used advantageously in particular when a final parking position intended for the vehicle cannot be reached by a single vehicle and the parking position can instead only be reached by a plurality of vehicles. By means of the method according to the invention, it can thus be ensured that all individual vehicles of a multi-vehicle parking maneuver can each be carried out with the desired speed profile.

[0025] In a further advantageous embodiment of the present invention, the respective PT1 elements are initialized as a function of a current speed and / or a current acceleration of the vehicle at the time the method is initiated. In a case in which the method is initiated from a stationary vehicle, the PT1 elements are correspondingly initialized with a value of zero. In the case in which the method is initiated from an active driving mode of the vehicle, the initialization of the respective PT1 elements ensures that a substantially continuous transition of the vehicle movement occurs at the time the method according to the invention is activated.

[0026] Advantageously, at least some of the gain factors and / or at least some of the maximum permissible value ranges of the limiters are adjusted depending on a current remaining distance and / or a predefined phase of a driving maneuver of the vehicle (e.g., an initial phase and an end phase of a parking maneuver). Furthermore, it is possible to consider boundary conditions deviating from this for adjusting the gain factors and / or the permissible value ranges of the limiters. Alternatively or additionally, it is possible for at least some of the gain factors and / or at least some of the maximum permissible value ranges of the limiters to be adjusted depending on a longitudinal dynamic behavior of the vehicle desired by a user of the vehicle during a driving maneuver.Furthermore, it is possible for such an adjustment to be made by the vehicle user before performing such a driving maneuver, in particular before a parking maneuver, and / or during the execution of the driving maneuver. For example, the desired longitudinal dynamic behavior can be adjusted by a user variably setting a desired value on a scale between a comfort mode and a dynamic mode. This setting can be achieved, for example, via a touch display and / or via a mobile device coupled to the vehicle and / or via a voice input function, etc.

[0027] In a further embodiment of the present invention, at least some of the gain factors and / or at least some of the maximum permissible value ranges of the limiters are determined by a plurality of users depending on a previously determined average preferred longitudinal dynamic behavior of the vehicle. This can be achieved, for example, during a development phase of the vehicle by utilizing a plurality of test drivers and / or by a crowdsourcing process in which user data from a plurality of users is centrally collected (e.g., via a wireless communication unit of the vehicle) and evaluated.

[0028] According to a second aspect of the present invention, a device for determining a speed profile for a vehicle along a path for the vehicle is proposed, wherein the device is configured, for example, based on an evaluation unit, to determine a current remaining distance along the path provided for the vehicle to reach a predefined stopping position for the vehicle, to determine a current target speed for the vehicle as a function of the remaining distance based on at least a first PT1 element and a second PT1 element, wherein a first signal representing the current remaining distance between the vehicle and the stopping position along the path is fed into an input of the first PT1 element, wherein an output of the first PT1 element is connected to an input of the second PT1 element, wherein an output of the second PT1 element is connected to an input of a first integrator,wherein an output of the first integrator is connected in a negative feedback manner to the input of the second PT1 element, wherein the output of the first integrator is connected to an input of a second integrator, wherein an output of the second integrator is connected in a negative feedback manner to the input of the first PT1 element, and wherein a second signal output at the output of the first integrator is used to set the current target speed for the vehicle. In addition, a gain factor of the first PT1 element and a gain factor of the second PT1 element are determined as a function of a desired longitudinal dynamic behavior for the vehicle. The features, combinations of features, and the advantages resulting therefrom correspond to those explained in connection with the first-mentioned aspect of the invention, so that reference is made to the above explanations to avoid repetition. Short description of the drawings

[0029] Embodiments of the invention will now be described in detail with reference to the accompanying drawings. In the drawing: Fig. 1 is a block diagram of an embodiment of a transmission system for determining a speed profile for a vehicle; Fig. 2 shows an exemplary course of a path according to the invention and a speed profile corresponding to the path; Fig. 3 a schematic view of a vehicle with a device according to the invention; and Fig. 4 a schematic view of a device according to the invention in conjunction with downstream components. Embodiments of the invention

[0030] Fig. 1 shows a block diagram of an embodiment of a transmission system for determining a speed profile for a vehicle along a path for the vehicle.

[0031] The transmission system, which can be used in a method and / or a device according to the invention, has a first PT1 element 40, a second PT1 element 42 and a third PT1 element 44, wherein respective outputs of the PT1 elements 40, 42, 44 are connected to respective corresponding limiters 60, 62, 64.

[0032] Following the series-connected PT1 elements 40, 42, 44 with their respective corresponding limiters 60, 62, 64, a third integrator 54, a first integrator 50 and a second integrator 52 are connected in series in this order.

[0033] An output of the third integrator 54 is connected in a negative feedback manner to an input of the third PT1 element 44. An output of the first integrator 50 is connected in a negative feedback manner to an input of the second PT1 element 42, and an output of the second integrator 52 is connected in a negative feedback manner to an input of the first PT1 element 40.

[0034] Specifically, a second signal S2 output from the second integrator 52 is subtracted from a first signal S1 representing a current remaining distance sxTar, so that a resulting difference signal is fed into the input of the first PT1 element 40.

[0035] The current remaining distance sxTar is a distance along the path intended for the vehicle to reach a predefined parking position. The current remaining distance sxTar is received, for example, by a parking module of the vehicle, which is configured to determine a suitable path to reach the parking position based, for example, on the vehicle's environmental sensors.

[0036] Based on the transmission system described above, it is then possible to determine a current target speed vxRef for the vehicle as a function of the remaining distance sxTar.

[0037] For this purpose, the second signal S2, which represents the current target speed vxRef, is provided at the output of the first integrator 50 and is then used to set the current target speed vxRef for the vehicle 10 in a downstream (not shown) control for the longitudinal movement of the vehicle.

[0038] A gain factor of the second PT1 element 42 is at least a factor of four greater than a gain factor of the first PT1 element 40, while a gain factor of the third PT1 element is at least a factor of four greater than the gain factor of the second PT1 element.

[0039] Furthermore, it is possible to adapt the amplification factors and / or the maximum permissible value ranges of the limiters 60, 62, 64 depending on a predefined phase of a driving maneuver of the vehicle and / or a longitudinal dynamic behavior of the vehicle desired by a user of the vehicle during the parking maneuver.

[0040] Alternatively or additionally, it is possible to use in the downstream control a third signal S3 representing a currently set position sxRef of the vehicle along the path, which is provided at the output of the second integrator 52.

[0041] Fig. 2 shows an exemplary course of a path according to the invention and a speed profile VxRef(t) corresponding to the path.

[0042] The upper diagram in Fig. 2 represents the distance sx traveled by a vehicle along a previously determined path as a function of time t, in other words a trajectory 20, until reaching a predefined stopping position for the vehicle, which is represented by an initially determined remaining distance sxTar.

[0043] Corresponding to this is the diagram below in Fig. 2 shows a speed profile VxRef(t) determined according to the invention, which represents the respective target speeds vx to be set for the vehicle as a function of time t.

[0044] A distinction is made between an initial phase P1 and an end phase P2, each of which has individually adapted values ​​for the phases in Fig. 1 described gain factors and / or permissible value ranges of the limiters, whereby a maximum permissible speed vxMax, which is determined by the first limiter 60 in Fig. 1 is ensured, here in both phases P1, P2 remains unchanged.

[0045] Fig. 3 shows a schematic view of a vehicle 10 with a device according to the invention, which has an evaluation unit 90 designed as a microcontroller.

[0046] By means of the evaluation unit 90, the vehicle 10 is able to determine a suitable speed profile VxRef(t) (see Fig. 2) along a path determined by the vehicle 10 to reach a parking position 30 for the vehicle.

[0047] The velocity profile VxRef(t) determined for the path corresponds, for example, to the one in Fig. 2 velocity profile VxRef(t) shown in the lower diagram, without being restricted to such a profile.

[0048] The path in conjunction with the determined velocity profile VxRef(t) for the path corresponds to a trajectory 20.

[0049] Fig. 4 shows a schematic view of an apparatus according to the invention for determining a speed profile for a vehicle along a path for the vehicle in conjunction with downstream components of the vehicle.

[0050] The device is represented here by an evaluation unit 90 designed as an ASIC, which is set up to receive information about a current remaining distance sxTar, about a current speed vxAct and about a current acceleration axAct of the vehicle from an upstream control unit (not shown) of the vehicle.

[0051] The evaluation unit 90 is further configured to read out values ​​for a maximum speed vxMax, for a minimum acceleration axMin, for a maximum acceleration axMax, for a minimum jerk jxMin and for a maximum jerk jxMax from a memory unit (not shown) that is connected to the evaluation unit 90 for information purposes, in order to store these values ​​in the Fig. 1, which is implemented by the evaluation unit 90, in the limiters 60, 62, 64.

[0052] The values ​​for the current speed vxAct and the current acceleration axAct are used to initialize the Fig. 1, while the current remaining distance sxTar is used as an input variable in the processing chain.

[0053] The current remaining distance sxTar is read in at a predefined processing cycle of the evaluation unit 90 and processed in the processing chain, while in accordance with the processing cycle, respective output values ​​in the form of currently set target speeds vxRef for the vehicle are output from the evaluation unit 90 to a post-processing component 70.

[0054] The post-processing component 70 is configured to convert the respective target speed values ​​vxRef into suitable signals for an actuator system 80 of the vehicle, which is provided for setting the target speed vxRef applicable at the respective time. The actuator system 80 includes, for example, a braking actuator and an acceleration actuator. QUOTES CONTAINED IN THE DESCRIPTION

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

[0000] Werling, M. 2011. "A New Concept for Trajectory Generation and Stabilization in Time-Critical Traffic Scenarios," Karlsruhe: KIT Scientific Publishing. DOI: https: / / doi.org / 10.5445 / KSP / 1000021738

[0005] Rathgeber, C.; Winkler, F.; Müller, S.: “Collision-free longitudinal and lateral trajectory planning taking vehicle-specific potentials into account,” In: at-Automatisierungstechnik 64 (2016), No. 1, pp. 61-76

[0005]

Claims

[1] Method for determining a speed profile (VxRef(t)) for a vehicle (10) along a path for the vehicle (10), comprising: - a first step for determining a current remaining distance (sxTar) along the path provided for the vehicle (10) to reach a predefined stopping position (30) for the vehicle (10), - a second step for determining a current target speed (vxref) for the vehicle (10) as a function of the remaining distance (sxTar) based on at least a first PT1 element (40) and a second PT1 element (42), wherein - a first signal (S1) representing the current remaining distance (sxTar) between the vehicle (10) and the stopping position (30) along the path is fed into an input of the first PT1 element (40), - an output of the first PT1 element (40) is connected to an input of the second PT1 element (42), - an output of the second PT1 element (42) is connected to an input of a first integrator (50), - an output of the first integrator (50) is connected in a negative feedback manner to the input of the second PT1 element (42), - the output of the first integrator (50) is connected to an input of a second integrator (52), - an output of the second integrator (52) is connected in a negative feedback manner to the input of the first PT1 element (40), and - a second signal (S2), which is output at the output of the first integrator (50), is used to set the current target speed (vxRef) for the vehicle (10), wherein - a gain factor of the first PT1 element (40) and a gain factor of the second PT1 element (42) are determined as a function of a desired longitudinal dynamic behavior for the vehicle (10), and - the process steps are carried out iteratively until the vehicle (10) reaches the stopping position (30). [2] The method according to claim 1, wherein - the output of the second PT1 element (42) is connected to the input of the first integrator (50) via a series circuit comprising a third PT1 element (44) and a third integrator (54), and - an output of the third integrator (54) is connected in a negative feedback manner to the input of the third PT1 element (44). [3] Method according to one of the preceding claims, wherein the amplification factors of the respective PT1 elements (40, 42, 44) differ by at least a factor of four compared to the PT1 element (40, 42, 44) immediately upstream in the processing chain. [4] Method according to one of the preceding claims, wherein at least a part of the output signals generated by the PT1 elements (40, 42, 44) is limited to maximum permissible value ranges by means of limiters (60, 62, 64) corresponding to the PT1 elements (40, 42, 44) before their further processing within the processing chain. [5] Method according to claim 4, wherein by means of the respective limiters (60, 62, 64) - a maximum speed (vxMax), and / or - a maximum acceleration (axMax) and / or minimum acceleration (axMin), and / or - a maximum jerk (jxMax) and / or minimum jerk (jxMin) must be ensured. [6] Method according to one of the preceding claims, wherein - the method is used to perform a parking maneuver for the vehicle (10), and / or - the stopping position (30) is a final parking position for the vehicle (10) and / or a position for an intermediate stop for the vehicle (10) during the parking maneuver. [7] Method according to one of the preceding claims, wherein the respective PT1 elements (40, 42, 44) are initialized as a function of a current speed (vxAct) and / or a current acceleration (axAct) of the vehicle (10) at the time of the start of the method. [8] Method according to one of the preceding claims, wherein at least some of the gain factors and / or at least some of the maximum permissible value ranges of the limiters (60, 62, 64) are determined as a function of - a current remaining distance (sxTar), and / or - a predefined phase of a driving maneuver of the vehicle (10), and / or - a longitudinal dynamic behavior of the vehicle (10) desired by a user of the vehicle (10) during a driving maneuver. [9] Method according to one of the preceding claims, wherein at least some of the amplification factors and / or at least some of the maximum permissible value ranges of the limiters (60, 62, 64) are determined by a plurality of users as a function of a previously determined average preferred longitudinal dynamic behavior of the vehicle (10). [10] Device for determining a speed profile (VxRef(t)) for a vehicle (10) along a path for the vehicle (10), the device being arranged - to determine a current remaining distance (sxTar) along the path provided for the vehicle (10) to reach a predefined stopping position (30) for the vehicle (10), - to determine a current target speed (vxRef) for the vehicle (10) as a function of the remaining distance (sxTar) based on at least a first PT1 element (40) and a second PT1 element (42), wherein ◯ a first signal (S1) representing the current remaining distance (sxTar) between the vehicle (10) and the stopping position (30) along the path is fed into an input of the first PT1 element (40), ◯ an output of the first PT1 element (40) is connected to an input of the second PT1 element (42), ◯ an output of the second PT1 element (42) is connected to an input of a first integrator (50), ◯ an output of the first integrator (50) is connected in a negative feedback manner to the input of the second PT1 element (42), ◯ the output of the first integrator (50) is connected to an input of a second integrator (52), ◯ an output of the second integrator (52) is connected in a negative feedback manner to the input of the first PT1 element (40), and ◯ a second signal (S2), which is output at the output of the first integrator (50), is used to set the current target speed (vxRef) for the vehicle (10), where - a gain factor of the first PT1 element (40) and a gain factor of the second PT1 element (42) are determined as a function of a desired longitudinal dynamic behavior for the vehicle (10).

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