Method and apparatus for longitudinal control of a vehicle

Abstract

The present invention calculates a series of target positions (P k-n ~P k+m ) to specify the target trajectory (T soll The present invention relates to a method for longitudinal control of a vehicle (1) as a function of the acceleration (a) of a controller for trajectory control based on the actual state (Z) of the vehicle (1). ctrl ) is determined, so that the vehicle (1) moves along the target trajectory (T soll ) and the vehicle (1) is accelerated according to the target trajectory (T soll ) at the current position of the vehicle (1), soll ) curvature (K) of the target trajectory (T soll ) and hence the acceleration offset (a offset ) is determined based on the curvature (K). Furthermore, when the vehicle (1) moves along the target trajectory (T soll ) while tracking the target trajectory (T soll ) is the current track acceleration (a refPtOrth ) and the controller actuation acceleration (a ctrl ) is the current orbital acceleration (a refPtOrth ) and acceleration offset (a offset The vehicle (1) is limited to a value equal to or less than the sum of the limited controller actuation acceleration (a ctrl_lim The invention also relates to a device (2) for longitudinal control of a vehicle (1).

Description

[Technical field]

[0001] The present invention relates to a method for longitudinal control of a vehicle.

[0002] The present invention also relates to an apparatus for longitudinal control of a vehicle. [Background technology]

[0003] DE102017010180B3 discloses an apparatus and a method for controlling the longitudinal position of a vehicle by a longitudinal position controller, which generates a longitudinal acceleration control signal for a subordinate acceleration control unit from a longitudinal dynamic pre-control setpoint variable and a longitudinal dynamic control error variable. A current control reference point corresponding to a current time point and a previous control reference point corresponding to a predeterminable look-ahead time point are determined as control-relevant time points. For each control reference point, the current or predicted actual / target deviations of the longitudinal position, the driving speed and the acceleration are determined and used as the basis for forming the longitudinal dynamic control error variable. Furthermore, a target acceleration value is determined for each control reference point and used as the basis for forming the longitudinal dynamic pre-control target value. The longitudinal dynamic pre-control setpoint is formed by weighting and adding the acceleration setpoints determined for the control reference points.

[0004] Furthermore, DE102017114471A1 discloses a vehicle control device configured to autonomously drive a vehicle. This vehicle control device includes a longitudinal position matching unit configured to recognize a longitudinal position corresponding to the position of the vehicle in the extension direction of the route along which the vehicle travels, based on image information from a camera and position information of a direction point on a map, a longitudinal position estimation unit configured to estimate the longitudinal position based on the detection result of an internal sensor that detects the state of the vehicle and the recognition result of the longitudinal position matching unit, an error estimation unit configured to estimate an error in the longitudinal position estimated by the longitudinal position estimation unit based on the detection accuracy of the internal sensor, a radius acquisition unit configured to acquire a curve radius of a curved road ahead of the vehicle using the estimated longitudinal position and map information, and a cornering speed calculation unit configured to calculate a cornering speed for the vehicle to autonomously travel along a lane on a curved road with the acquired cornering radius, based on the acquired cornering radius and the estimated longitudinal position error. a speed control unit configured to decelerate the vehicle so that the vehicle speed becomes the cornering speed at the time of entering a curved road in front of the vehicle when the vehicle speed is equal to or greater than the cornering speed and the cornering speed is equal to or greater than a preset reference speed, and configured to maintain the current speed or decelerate the vehicle so that the vehicle speed becomes the reference speed at the time of entering a curved road in front of the vehicle when the vehicle speed is equal to or greater than the cornering speed and the cornering speed is less than the reference speed; and a request unit configured to make a manual operation request to switch control of the vehicle to manual operation by the driver when the vehicle speed is equal to or greater than the cornering speed and the cornering speed is less than the reference speed, and the cornering speed calculation unit is configured to lower the cornering speed when the cornering radius is smaller than when the cornering radius is large, and to lower the cornering speed when the error in the longitudinal direction position is larger than when the error in the longitudinal direction position is small.

[0005] DE102018210648A1 describes a longitudinal driving assistance system for a motor vehicle with a detection system for predictive detection of a number of events, each of which leads to a change in the target speed based on the currently reached target speed, and a functional unit capable of activating an event selection function if a number of events occur relatively close together within a given observation period, which event selection function can be used in a first step to determine a corrected target speed for the longitudinal guidance control, such that only events that lead to a reduction in the target speed based on the actual speed are selected. Summary of the Invention

[0006] SUMMARY OF THE PRESENT EMBODIMENT It is an object of the present invention to provide a novel method and apparatus for providing longitudinal control of a vehicle.

[0007] According to the invention the problem is solved by a method having the features of claim 1 and by a device having the features of claim 7 .

[0008] Advantageous embodiments of the invention are the subject matter of the dependent claims.

[0009] In a method for longitudinal control of a vehicle according to the present invention, a controller actuated acceleration for trajectory control is determined based on an actual state of the vehicle as a function of a target trajectory specifying a series of target positions to be taken by the vehicle over time, whereby the vehicle is accelerated as specified by the target trajectory. When the vehicle is following the target trajectory, a curvature of the target trajectory at the vehicle's current position is determined from a local course of the target trajectory, whereby an acceleration offset that decreases with increasing curvature is determined based on the curvature. Furthermore, when the vehicle is following the target trajectory, a longitudinal acceleration resulting from the target trajectory is determined as a current trajectory acceleration at the vehicle's current position. The controller actuated acceleration is limited to a value equivalent to less than or equal to the sum of the current trajectory acceleration and the acceleration offset, and the vehicle is accelerated according to the limited controller actuated acceleration.

[0010] Trajectory control of an automated, especially a highly automated or autonomous vehicle, is a fundamental prerequisite for realizing automated driving functions. It involves determining what actions the vehicle should perform in the future based on data from an environment detection system. The result of this determination is, for example, a trajectory that maps the position of the vehicle on the road over time and serves as a movement reference in the known vehicle environment. Trajectory control is intended to follow the trajectory as accurately as possible. If for some reason a large longitudinal position control error accumulates, the trajectory specification at the target position will not match the trajectory specification at the actual position on the road where the vehicle is currently located. This means that the "target time" continues to progress. For example, when the vehicle is driving around a sharp curve, there is a risk that the vehicle will automatically accelerate because the time reference point, i.e. the target position, is already far ahead of the trajectory, for example on the straight line after the curve.

[0011] In this method, the deviation between a local reference point, i.e. the actual position of the vehicle, and a time reference point, i.e. the target position of the vehicle on the trajectory, is taken into account in the longitudinal control of the vehicle. This method is used to limit the target acceleration specification if it is too high at the actual position. Such a curvature-dependent acceleration limit at the actual position makes it possible to prevent dangerous situations resulting from excessive acceleration, for example excessive acceleration on sharp curves.

[0012] In other words, the method enables safe trajectory maneuver aimed at reaching a planned position at a relevant time, thereby limiting, if necessary, the acceleration at the actual position by a curvature-dependent acceleration limit less than or equal to the acceleration specified at the target position.

[0013] In a possible embodiment of the method, the actual state of the vehicle is formed from at least the actual speed of the vehicle, the actual acceleration of the vehicle and / or the actual position of the vehicle, with these variables the actual state can be easily represented and therefore the controller actuation acceleration can be reliably determined.

[0014] In another possible embodiment of the method, the actual position or the next target position from the series of target positions is used as the current position of the vehicle, which makes it possible to determine the current position of the vehicle easily and with sufficient accuracy to determine the curvature.

[0015] In another possible embodiment of the method, the longitudinal acceleration resulting from the target trajectory is determined from the change in distance over time between successive target positions of the target trajectory, which facilitates the determination of the current trajectory acceleration.

[0016] In another possible embodiment of the method, the target trajectory is provided to a trajectory controller, which accelerates the vehicle as specified in the target trajectory using a controller actuated acceleration, and the limited controller actuated acceleration is provided to an acceleration controller subordinate to the trajectory controller and which controls and / or regulates the actual acceleration of the vehicle.

[0017] In another possible embodiment of the method, the target trajectory is recalculated if a predefined difference between the predefined controller actuation acceleration and the limited controller actuation acceleration is exceeded, thus minimizing the deviation of the target trajectory from the actual trajectory, and, consequently, the deviation of the controller actuation acceleration from the corrected controller actuation acceleration.

[0018] The device for longitudinal control of a vehicle as a function of a target trajectory according to the present invention comprises a trajectory controller, the target trajectory specifying a series of target positions to be taken by the vehicle over time, the trajectory controller using the supplied target trajectory to determine a controller actuated acceleration for trajectory control based on the actual state of the vehicle, whereby the vehicle is accelerated according to the target trajectory specification. The device also comprises a pre-processing unit for determining a curvature of the target trajectory at the current position of the vehicle from the local course of the target trajectory if the vehicle is following the target trajectory. The pre-processing unit further uses the curvature to determine an acceleration offset that decreases as the curvature increases, and determines the longitudinal acceleration resulting from the target trajectory as the current trajectory acceleration at the current position of the vehicle if the vehicle is following the target trajectory. The device further comprises a limiting unit for limiting the controller actuated acceleration to a value corresponding to less than or equal to the sum of the current trajectory acceleration and the acceleration offset, and an acceleration control unit subordinate to the trajectory controller and accelerating the vehicle according to the limited controller actuated acceleration.

[0019] This device allows the deviation between a local reference point, i.e. the actual position of the vehicle, and a time reference point, i.e. the target position of the vehicle on the trajectory, to be taken into account in the longitudinal control of the vehicle. This device limits the target acceleration specification if it is too high at the actual position. Such a curvature-dependent acceleration limit at the actual position makes it possible to prevent dangerous situations resulting from excessive acceleration, for example excessive acceleration on sharp curves.

[0020] In other words, the device enables safe trajectory control aimed at reaching a planned position at a relevant time, thereby limiting, if necessary, the acceleration at the actual position by a curvature-dependent acceleration limit less than or equal to the acceleration specified value at the target position.

[0021] In a possible embodiment of the device, the acceleration control unit is a vehicle braking system, which can be used to simply and reliably set a limited controller controlled acceleration.

[0022] In another possible embodiment of the device, the device comprises a control error monitoring unit which recalculates the target trajectory if a predefined difference between the predefined controller actuation acceleration and the limited controller actuation acceleration is exceeded, in this way the deviation of the target trajectory from the actual trajectory and, as a consequence, the deviation of the controller actuation acceleration from the corrected controller actuation acceleration can be minimized.

[0023] Exemplary embodiments of the invention are explained in more detail below with reference to the drawings. [Brief description of the drawings]

[0024] [Figure 1] FIG. 2 is a schematic plan view of a traffic situation with vehicles in actual and target positions; [Diagram 2] FIG. 2 is a schematic diagram of vehicle acceleration and velocity over time. [Diagram 3] 1 is a schematic block diagram of an apparatus for longitudinal control of a vehicle; [Figure 4] FIG. 2 is a schematic diagram of the course of a target trajectory of a vehicle. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0025] Corresponding parts are given the same reference numbers in all figures.

[0026] Figure 1 shows the actual position of vehicle 1. ist and target position P kon some track sections T soll1 ~T soll3 A target trajectory T soll 2 shows the curves of acceleration a and speed v of the vehicle 1 according to FIG.

[0027] The vehicle 1 is designed to perform automatic driving, particularly highly automated driving or autonomous driving. To realize such an automatic driving function, trajectory control is a major prerequisite.

[0028] In this trajectory control, a decision is made as to what action the vehicle 1 should take in the future based on data UD from the environment detection system shown in detail in FIG. 3. The result of this decision is the target trajectory T soll which represents, for example, the position on the road of the vehicle 1 over time t and serves as a moving reference in the known vehicle environment. The trajectory control is intended to follow the trajectory as accurately as possible. If for some reason a large longitudinal position control error accumulates, the target position P k The trajectory specification in is the actual position P ist This means that the "target time" continues to progress.

[0029] Taking a roundabout as an example, the actual position P ist is the target position P k The actual position P ist is in the roundabout, but the target position P k is already outside the roundabout after leaving the roundabout.

[0030] As shown in Figure 2, the target trajectory T soll According to the speed profile and acceleration profile assigned to the track section T soll2 Let us assume that the vehicle travels through the roundabout at a low constant speed v and travels along the track section T after the roundabout until it reaches a high speed v. soll3 The purpose is to accelerate more strongly in the track section T soll3The acceleration profile for the track section T soll2 It is not suitable for use on roads with

[0031] However, as shown in FIG. 1, the time reference point, i.e., the orbital section T soll3 Target position P at k and the local reference point, i.e., the track section Tsoll2 The actual position P ist Since the distance between the track section and the track section T is large, vehicle 1 is soll2 , and there is a risk of accelerating automatically, since the time reference point is already far ahead, in this case the track section T soll3 This is because it is located on a straight line after the roundabout at .

[0032] In this situation, a typical trajectory controller would cause vehicle 1 to accelerate faster through the roundabout in an attempt to compensate for the longitudinal position error. Depending on the amount of curvature K in the path, this situation is generally undesirable and potentially dangerous.

[0033] Such errors occur when the control error becomes large and the target trajectory T soll This can also occur if the autonomous driving system of the vehicle 1 has a so-called control error monitoring module that reschedules the target trajectory T soll If the threshold for redefining the

[0034] However, the actual position P ist There is still track section T soll2 Instead, track section T soll1 and the vehicle 1 is still decelerating, this does not pose a safety problem: in this case the control error will be even larger, but no undesirable acceleration a will occur.

[0035] FIG. 3 shows a block diagram of a device 2 for longitudinal control of a vehicle 1 .

[0036] The device 2 calculates a target trajectory T based on the data UD recorded by the environment detection sensor 4. soll The system comprises a first computing unit 3 having a trajectory planning module 3.1 for planning a trajectory.

[0037] Target position P k In order to solve the problem shown in Figs. 1 and 2, where the deviation of the actual position Pist from the target trajectory T soll is fed to a further computing unit 5 which comprises a pre-processing unit 5.1, a trajectory controller 5.2, a characteristic curve 5.3, a maximum value detector 5.4 and a limiting unit 5.5.

[0038] Vehicle 1 follows target trajectory T soll , the pre-processing unit 5.1 calculates the target trajectory T soll From the local course of vehicle 1, the target trajectory T soll Derive the curvature K of.

[0039] The pre-processing unit 5.1 uses a characteristic curve 5.3 representing the acceleration a of the vehicle 1 as a function of the curvature K to calculate the acceleration offset a, which decreases with increasing curvature K, in particular using future prediction information. offset This acceleration offset a offset may also be formed as a function of the friction value of the road surface and forms the permissible acceleration deviation.

[0040] Furthermore, vehicle 1 follows the target trajectory T soll , the pre-processing unit 5.1 calculates the target trajectory T soll The longitudinal acceleration resulting from the vehicle 1 is calculated based on the current position of the vehicle 1, for example, the actual position P ist Current orbital acceleration a refPtOrth and feed it to the limiting unit 5.5. This orbital acceleration a refPtOrth is the reference acceleration at the trajectory point closest to the current position of vehicle 1.

[0041] Also, the actual position of vehicle 1, P ist For the target trajectory Tsoll A series of target positions P k-n ~P k+m The next target position P k may be used as the current position of the vehicle 1.

[0042] Target trajectory T soll The longitudinal acceleration resulting from the target trajectory T soll Successive target positions P k-n ~P k+m It can be determined from the change in distance between them over time.

[0043] And the acceleration offset a offset and orbital acceleration a refPtOrth are added together and the sum is also fed to the limiting unit 5.5.

[0044] Furthermore, the trajectory controller 5.2 determines the target trajectory T soll Based on the actual state Z of the vehicle 1, the controller operates acceleration a ctrl , and vehicle 1 follows the target trajectory T soll The actual state Z of vehicle 1 is, for example, the actual speed v ist , the actual acceleration a ist , the actual position P ist It is characterized by:

[0045] Acceleration offset a by limit unit 5.5 offset and orbital acceleration a refPtOrthと Operating acceleration a ctrl The limited controller actuation acceleration a is determined according to the following formula using the minimum of the sum of ctrl_lim Calculate.

[0046]

number

[0047] Orbital acceleration a greater than positive parameter Par refPtOrthOnly the negative trajectory acceleration a is taken into account, otherwise the vehicle 1 would stop during the deceleration phase. In this case, refPtOrth is always a positive controller actuation acceleration a in the subsequent acceleration phase. ctrl will be smaller than

[0048] Limited controller operating acceleration a ctrl_lim is fed to the acceleration control unit 6 subordinate to the orbit controller 5.2, which controls the limited controller actuation acceleration a ctrl_lim The acceleration control unit 6 is, for example, a vehicle braking system. Thus, the control system output is the local track acceleration a refPtOrth It will never be larger than that.

[0049] Therefore, in the situation shown in FIG. 1, the vehicle 1 is at an actual position P ist On the other hand, on a straight road the vehicle 1 can accelerate strongly enough to compensate for the control error.

[0050] FIG. 4 shows a possible target trajectory T soll The target trajectory T soll is the time t k-n ~t k+m At each point in time, a series of target positions P that vehicle 1 should take over time t k-n ~P k+m Specify. [Explanation of symbols]

[0051] 1 vehicle 2 equipment 3 Calculation Unit 3.1 Trajectory Planning Module 4. Environmental detection sensor system 5 Calculation Unit 5.1 Processing Module 5.2 Orbit Controller 5.3 Characteristic curve 5.4 Maximum Detector 5.5' Limit Unit 6 Acceleration Controller a acceleration a ctrl Controller operation acceleration a ctrl_lim Limited controller actuation acceleration a ist Actual Acceleration a offset Acceleration Offset a refPtOrth orbital acceleration K curvature Par Parameter P ist Actual location P k-n ~P k+m target position t time t k-n ~t k+m Time T soll target trajectory T soll1 ~ Tsoll3 Track section UD Data v speed v ist Actual speed Z Actual state

Claims

1. A series of target positions (P ｋ－ｎ ~P ｋ＋ｍ ) to specify the target trajectory (T ｓｏｌｌ 1. A method for longitudinal control of a vehicle (1) by means of a device (2) as a function of The trajectory controller (5.2) of the device (2) determines the controller operating acceleration (a) for trajectory control based on the actual state (Z) of the vehicle (1). ｃｔｒｌ ), whereby the vehicle (1) follows the target trajectory (T ｓｏｌｌ ) accelerated according to the specification of A pre-processing unit (5.1) of the device (2) determines whether the vehicle (1) is moving in the direction of the target trajectory (T ｓｏｌｌ ) at the current position of the vehicle (1), ｓｏｌｌ ) is the curvature (K) of the target trajectory (T ｓｏｌｌ ) from the local course of the The pre-processing unit (5.1) calculates an acceleration offset (a) based on the curvature (K) and decreases with increasing curvature (K). ｏｆｆｓｅｔ ) The pre-processing unit (5.1) determines whether the vehicle (1) is on the target trajectory (T ｓｏｌｌ ), the target trajectory (T ｓｏｌｌ ) is the current track acceleration (a ｒｅｆＰｔＯｒｔｈ ) The controller actuation acceleration (a ｃｔｒｌ ) to the current trajectory acceleration (a ｒｅｆＰｔＯｒｔｈ ) and the acceleration offset (a ｏｆｆｓｅｔ ) and limiting the value to a value equal to or less than the sum of The acceleration control unit (6) of the device (2) controls the limited controller actuation acceleration (a ｃｔｒｌ＿ｌｉｍ accelerating the vehicle (1) according to A method comprising:

2. The actual state (Z) of the vehicle (1) is determined by at least the actual speed (v ｉｓｔ ), actual acceleration (a ｉｓｔ ) and / or actual position (P ｉｓｔ 2. The method of claim 1 , wherein the polyisocyanate is formed from

3. The current position of the vehicle (1) is determined as the set of target positions (P ｋ－ｎ ~P ｋ＋ｍ ) of the actual position (P ｉｓｔ ) or the next target position (P ｋ 3. The method according to claim 1, wherein a .alpha.-phenylenediamine is used.

4. The target trajectory (T ｓｏｌｌ The longitudinal acceleration resulting from the target trajectory (T ｓｏｌｌ ) consecutive target positions (P ｋ－ｎ ~P ｋ＋ｍ The method according to any one of claims 1 to 3, wherein the distance between the first and second electrodes is determined from a change in distance over time.

5. The target trajectory (T ｓｏｌｌ ) is fed to the trajectory controller (5.2), so that the vehicle (1) is controlled by the controller actuated acceleration (a ｃｔｒｌ ) to obtain the target trajectory (T ｓｏｌｌ ) is accelerated according to the specifications, The limited controller actuation acceleration (a ｃｔｒｌ＿ｌｉｍ 5. The method according to claim 1, wherein the acceleration (a) of the vehicle (1) is controlled by the trajectory controller (5.2) and is fed to an acceleration control unit (6), which is subordinate to the trajectory controller (5.2) and controls and / or regulates the actual acceleration (a) of the vehicle (1).

6. The control error monitoring unit of the device (2) detects a predetermined controller operating acceleration (a ｃｔｒｌ ) and the limited controller actuation acceleration (a ｃｔｒｌ＿ｌｉｍ ) exceeds a predetermined difference between the target trajectory (T ｓｏｌｌ 6. The method according to claim 1, wherein a recalculation of .times. ...

7. A series of target positions (P ｋ－ｎ ~P ｋ＋ｍ ) to specify the target trajectory (T ｓｏｌｌ 2. A device (2) for longitudinal control of the vehicle (1) as a function of A trajectory controller (5.2) for a given target trajectory (T ｓｏｌｌ ) to determine the controller operating acceleration (a) for trajectory control based on the actual state (Z) of the vehicle (1). ｃｔｒｌ ), so that the vehicle (1) follows the target trajectory (T ｓｏｌｌ said trajectory controller (5.2) being accelerated according to the instructions of A pre-treatment unit (5.1), The vehicle (1) is ｓｏｌｌ ) at the current position of the vehicle (1), ｓｏｌｌ ) is the curvature (K) of the target trajectory (T ｓｏｌｌ ) determined from the local course of Based on the curvature (K), an acceleration offset (a ｏｆｆｓｅｔ ) and The vehicle (1) is ｓｏｌｌ ), the target trajectory (T ｓｏｌｌ ) is the current track acceleration (a ｒｅｆＰｔＯｒｔｈ said pre-processing unit (5.1) for determining the A limiting unit (5.5) for adjusting the controller actuation acceleration (actrl) to the current trajectory acceleration (a ｒｅｆＰｔＯｒｔｈ ) and acceleration offset (a ｏｆｆｓｅｔ said limiting unit (5.5) limiting the value to a value equal to or less than the sum of An acceleration control unit (6) subordinate to the orbit controller (5.2) controls the limited controller actuation acceleration (a ｃｔｒｌ＿ｌｉｍ an acceleration control unit (6) for accelerating the vehicle (1) according to An apparatus (2).

8. 8. The device (2) according to claim 7, wherein the acceleration control unit (6) is a vehicle braking system.

9. A control error monitoring unit is provided, the control error monitoring unit being configured to detect a predetermined controller operating acceleration (a ｃｔｒｌ ) and the limited controller actuation acceleration (a ｃｔｒｌ＿ｌｉｍ ) exceeds a predetermined difference between the target trajectory (T ｓｏｌｌ 9. The device (2) according to claim 7 or 8, further comprising a recalculation unit (10) for performing a recalculation of .

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