CN112810611B - Lateral trajectory tracking method and system for lane change control - Google Patents

Lateral trajectory tracking method and system for lane change control Download PDF

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CN112810611B
CN112810611B CN201911046914.0A CN201911046914A CN112810611B CN 112810611 B CN112810611 B CN 112810611B CN 201911046914 A CN201911046914 A CN 201911046914A CN 112810611 B CN112810611 B CN 112810611B
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curve
acceleration
lateral
vehicle
lane change
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CN112810611A (en
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张统凯
余建宏
徐锦衍
古昆陇
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Automotive Research and Testing Center
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60W—CONJOINT CONTROL OF VEHICLE SUB-UNITS OF DIFFERENT TYPE OR DIFFERENT FUNCTION; CONTROL SYSTEMS SPECIALLY ADAPTED FOR HYBRID VEHICLES; ROAD VEHICLE DRIVE CONTROL SYSTEMS FOR PURPOSES NOT RELATED TO THE CONTROL OF A PARTICULAR SUB-UNIT
    • B60W30/00—Purposes of road vehicle drive control systems not related to the control of a particular sub-unit, e.g. of systems using conjoint control of vehicle sub-units, or advanced driver assistance systems for ensuring comfort, stability and safety or drive control systems for propelling or retarding the vehicle
    • B60W30/18—Propelling the vehicle
    • B60W30/18009—Propelling the vehicle related to particular drive situations
    • B60W30/18163—Lane change; Overtaking manoeuvres

Abstract

In the method and the system for tracking the lateral track for lane change control, a processing unit estimates the longitudinal displacement, the lateral displacement and the azimuth offset of a vehicle in future unit time according to the vehicle speed, the angular speed and the acceleration measured by an inertial measurement unit at the current time point; estimating current position data of the position of the vehicle at the current time point according to the lane detection module; converting a reference lateral trajectory curve contained in a reference vehicle transformation trajectory curve estimated by the lane transformation assisting system relative to the position of the vehicle at the current time point into a lateral trajectory curve relative to the position of the vehicle at a future unit time point through coordinate conversion according to the estimated current position data, the longitudinal and lateral displacement amounts and the azimuth offset amount; and generating a target lateral track curve according to the acceleration threshold, the jerk threshold and the lateral track curve. Thus, the vehicle jump phenomenon caused by the sharp change of the steering control command can be effectively avoided.

Description

Lateral trajectory tracking method and system for lane change control
Technical Field
The present invention relates to lane change control for autonomous vehicles, and more particularly, to a lateral trajectory tracking method and system for lane change control.
Background
Currently, an Advanced Driving Assistance System (ADAS) applied to a vehicle includes, for example, an Automatic Emergency Braking (AEB) System, an Adaptive Cruise Control (ACC) System, a Lane Following System (LFS), a Forward Collision Warning (FCW) System, a Lane Departure Warning (LDW) System, a Blind Spot Detection (BSD) System, a Rear Cross Traffic Alert (RCTA) System, a Lane Keeping Assistance System (LKAS) System, and the like. International production regulations predict that the vehicle installation rate of ADAS will reach 40% in 2020 and more 60% in 2025.
The LKAS and/or Lane Following System (LFS) currently installed in domestic cars are used to provide steering control to modify the direction of travel of the vehicle to ensure that the vehicle travels smoothly in the detected Lane (i.e., the original Lane range), but the steering modification function is deactivated when the vehicle crosses the Lane line. On the other hand, the lane change control system installed in the high-grade import car can detect the obstacles around the vehicle and plan a proper and safe lane change track when the driver activates the turn signal (i.e. commonly called "turn signal"), so that the vehicle can move to the lane to be changed along the lane change track.
However, particularly in the case where the vehicle has been subjected to the control of the LKAS or LFS system before changing lanes (that is, before the lane change control system is activated), since the trajectory of the change path (i.e., the target trajectory) planned by the lane change control system is generally a cubic curve (which can be expressed by a cubic curve equation), and as the vehicle crosses the lane line, the LKAS or LFS system begins to re-plan the (new) target path (i.e., the centerline of the other lane of the transition), therefore, how to make the vehicle keep smooth steering control when the target track of the cubic curve is switched to the target track of the central line of the other lane in the steering control, it is an important subject to avoid the occurrence of vehicle bouncing phenomenon (vehicle occupant feels irregularity) caused by a sharp change in the steering control command.
Disclosure of Invention
It is an object of the present invention to provide a lateral trajectory tracking method for lane change control that overcomes at least one of the disadvantages of the prior art described above.
The invention provides a lateral trajectory tracking method for lane change control, which is implemented by a processing unit and comprises the following steps: (A) estimating current position data of a position of a reference point of a vehicle at a current time point based on lane line data obtained by a lane sensing module provided in the vehicle based on a plurality of images previously sensing the lane, when receiving a reference lane change trajectory curve estimated by a lane change assistance system provided in the vehicle traveling in a lane with respect to the position of the reference point of the vehicle at the current time point; (B) estimating the longitudinal displacement, the lateral displacement and the azimuth offset of the vehicle in unit time in the future according to the speed, the angular speed and the acceleration of the vehicle measured by an inertia measuring unit arranged on the vehicle at the current time point; (C) converting the reference lane change trajectory curve into a lane change trajectory curve of an estimated position at a future unit time point relative to the reference point of the vehicle by using a coordinate conversion mode according to the estimated current position data, the longitudinal displacement amount, the lateral displacement amount, and the azimuth offset amount; (D) decomposing the lane change track curve into a lateral track curve and a longitudinal track curve; and (E) generating a target lateral track curve according to a preset acceleration threshold, a preset jerk threshold and the lateral track curve by using a preset trapezoidal acceleration curve model, so that the absolute value of the acceleration value of the target lateral acceleration curve obtained after the target lateral track curve is subjected to two times of differential processing is not greater than the preset acceleration threshold, and the absolute value of the jerk value of the target lateral jerk curve obtained after the target lateral track curve is subjected to three times of differential processing is not greater than the preset jerk threshold.
According to the lateral trajectory tracking method for lane change control, the processing unit firstly filters noise of the angular velocity and the acceleration by using a Kalman filtering mode, then estimates the yaw rate and the lateral acceleration of the vehicle by using a Kalman estimation mode according to the filtered angular velocity and the filtered acceleration, estimates the azimuth offset and the lateral displacement according to the yaw rate, the lateral acceleration and the unit time, and estimates the longitudinal displacement according to the velocity, the yaw rate and the unit time.
The invention discloses a lateral track tracking method for lane change control, wherein the preset acceleration threshold is 3m/s2And the predetermined jerk threshold is 5m/s3。
The invention discloses a lateral track tracking method for lane change control, wherein the step (E) comprises the following sub-steps: (E1) performing, by the processing unit, differential processing on the lateral trajectory curve twice to obtain a reference curve; (E2) modifying, by the processing unit, the reference curve with a predetermined trapezoidal acceleration curve model to obtain a reference lateral acceleration curve, wherein the reference lateral acceleration curve has a first trapezoidal curve segment having an acceleration value of not less than zero, and a second trapezoidal curve segment connecting the first trapezoidal curve segment having an acceleration value of not more than zero, and the second trapezoidal curve segment is mapped to the first trapezoidal curve segment in acceleration values; (E3) planning a sine-like wave curve as a target acceleration curve according to the reference lateral acceleration curve, the predetermined acceleration threshold and the predetermined jerk threshold by the processing unit, so that the sine-like wave curve has a first curve segment and a second curve segment connected with the first curve segment, wherein the first curve segment has an acceleration value not less than zero but not more than the predetermined acceleration threshold, the second curve segment has an acceleration value not more than zero and an absolute value not more than the predetermined acceleration threshold, and each of the first curve segment and the two curve segments has an absolute value not more than the predetermined jerk threshold after being subjected to a differential processing; and (E4) performing, by the processing unit, twice integration processing on the target lateral acceleration curve to obtain the target lateral trajectory curve.
The lateral trajectory tracking method for lane change control according to the present invention further includes, after the step (E), the steps of: (F) generating a target lane change trajectory curve with respect to an estimated position of the reference point of the vehicle at the future unit time point according to the longitudinal trajectory curve and the target lateral trajectory curve, and outputting the target lane change trajectory curve to the lane change assistance system.
It is another object of the present invention to provide a lateral trajectory tracking system for lane change control that overcomes at least one of the disadvantages of the prior art described above.
The invention provides a lateral trajectory tracking system for lane change control, which is suitable for being combined with a lane change auxiliary system of a vehicle running on a lane and comprises a lane detection module, an inertia measurement unit and a processing unit.
The lane detection module is arranged on the vehicle and used for continuously sensing images of the lane so as to generate lane line data corresponding to the current time point according to a plurality of previously sensed images.
The inertia measurement unit is disposed on the vehicle and is configured to continuously measure a speed, an angular velocity, and an acceleration of the vehicle to generate a measurement result including the speed, the angular velocity, and the acceleration.
The processing unit is electrically connected with the lane detection module and the inertia measurement unit to receive the lane line data from the lane detection module and the measurement result from the inertia measurement unit, is suitable for being connected with the lane change auxiliary system, and executes the following operations when receiving a reference lane change track curve estimated by the lane change auxiliary system relative to the position of a reference point of the vehicle at the current time point: estimating current position data of the position of the reference point of the vehicle at the current time point according to the lane line data; estimating the longitudinal displacement, the lateral displacement and the azimuth offset of the vehicle in the future unit time according to the measurement result at the current time point; converting the reference lane change trajectory curve into a lane change trajectory curve of an estimated position at a future unit time point relative to the reference point of the vehicle by using a coordinate conversion mode according to the estimated current position data, the longitudinal displacement amount, the lateral displacement amount, and the azimuth offset amount; decomposing the lane change track curve into a lateral track curve and a longitudinal track curve; and generating a target lateral track curve according to a preset acceleration threshold, a preset jerk threshold and the lateral track curve by using a preset trapezoidal acceleration curve model, so that the absolute value of the acceleration value of the target lateral acceleration curve obtained after the target lateral track curve is subjected to twice differential processing is not greater than the preset acceleration threshold, and the absolute value of the jerk value of the target lateral jerk curve obtained after the target lateral track curve is subjected to three times differential processing is not greater than the preset jerk threshold.
In the system for tracking a lateral trajectory for lane change control according to the present invention, the processing unit first filters noise of the angular velocity and the acceleration by using a kalman filter, then estimates a yaw rate and a lateral acceleration of the vehicle by using a kalman estimation method according to the filtered angular velocity and the filtered acceleration, estimates the azimuth offset and the lateral displacement according to the yaw rate, the lateral acceleration and the unit time, and estimates the longitudinal displacement according to the velocity, the yaw rate and the unit time.
The invention provides a lateral trajectory tracking system for lane change control, the inertial measurement unit comprising: a gyroscope operative to sense the angular velocity of the vehicle; an accelerometer operative to sense the acceleration of the vehicle; and a speed sensor operative to sense the speed of the vehicle.
The lateral trajectory tracking system for lane change control of the present invention, the predetermined acceleration threshold is 3m/s2And the predetermined jerk threshold is 5m/s3。
The invention relates to a lateral trajectory tracking system for lane change control, the processing unit executes the following operations: performing differential processing on the lateral track curve twice to obtain a reference curve; modifying the reference curve with a predetermined trapezoidal acceleration curve model to obtain a reference lateral acceleration curve, wherein the reference lateral acceleration curve has a first trapezoidal curve segment with an acceleration value of not less than zero, and a second trapezoidal curve segment connecting the first trapezoidal curve segment with an acceleration value of not more than zero, and the second trapezoidal curve segment is mapped to the first trapezoidal curve segment in acceleration values; planning a sine-like wave curve as a target acceleration curve according to the reference lateral acceleration curve, the predetermined acceleration threshold and the predetermined jerk threshold by the processing unit, so that the sine-like wave curve has a first curve segment and a second curve segment connected with the first curve segment, wherein the first curve segment has an acceleration value not less than zero but not more than the predetermined acceleration threshold, the second curve segment has an acceleration value not more than zero and an absolute value not more than the predetermined acceleration threshold, and each of the first curve segment and the two curve segments has an absolute value not more than the predetermined jerk threshold after being subjected to a differential processing; and performing twice integration processing on the target lateral acceleration curve through the processing unit to obtain the target lateral trajectory curve.
In the lateral trajectory tracking system for lane change control according to the present invention, the processing unit generates a target lane change trajectory curve corresponding to an estimated position of the reference point of the vehicle at the future unit time point based on the longitudinal trajectory curve and the target lateral trajectory curve, and outputs the target lane change trajectory curve to the lane change assist system.
The invention has the beneficial effects that: since the target lateral trajectory curve is not greater than the predetermined acceleration threshold in terms of lateral acceleration and not greater than the predetermined jerk threshold in terms of lateral jerk, the target lane change trajectory curve planned using the target lateral trajectory curve can effectively avoid a vehicle bounce phenomenon caused by an abrupt change in a steering control command (e.g., a lateral jerk greater than the predetermined lateral jerk threshold, or a lateral acceleration greater than the predetermined lateral acceleration threshold).
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Other features and effects of the present invention will become apparent from the following detailed description of the embodiments with reference to the accompanying drawings, in which:
FIG. 1 is a block diagram illustrating an embodiment of the lateral trajectory tracking system for lane change control of the present invention;
FIG. 2 is a schematic diagram illustrating an example of a situation where a vehicle traveling in one lane is about to change to an adjacent right lane;
FIG. 3 is a flow chart illustrating how the processing unit of the embodiment performs the lateral trajectory tracking method of the present invention in the context of FIG. 2;
FIG. 4 is a schematic diagram illustrating another scenario in which the vehicle is about to change to an adjacent right lane;
FIG. 5 is a flow chart illustrating the sub-steps of step 306 in FIG. 3;
FIG. 6 illustrates an example of a lateral trajectory curve in the case of FIG. 2;
FIG. 7 is a plot of a reference lateral acceleration curve obtained from the lateral trajectory curve of FIG. 6;
FIG. 8 depicts a target lateral acceleration curve corresponding to the lateral trajectory curve of FIG. 6; and
fig. 9 is a graph illustrating a target lateral jerk curve obtained by first-order differential processing of the target lateral acceleration curve of fig. 8.
Detailed Description
Before the present invention is described in detail, it should be noted that in the following description, like elements are represented by like reference numerals.
Referring to fig. 1 and 2, the embodiment of the lateral trajectory tracking system 100 for lane change control according to the present invention can be applied to a vehicle (e.g., the vehicle 200 shown in fig. 2) traveling in a lane (e.g., the lane 401 shown in fig. 2), and is suitable for use in conjunction with the lane change assist system 4 installed in the vehicle 200. The lane change assist system 4 is configured to automatically estimate a reference lane change trajectory curve (e.g., the cubic curve C1 shown in fig. 2) by using a known environment sensing manner after confirming that there is a safe driving space when the vehicle 200 intends to change lanes (e.g., when the driver activates the turn signal), and generate a relevant steering control command according to the reference lane change trajectory curve, so that a powertrain and a steering system (not shown) of the vehicle 200 can automatically move the vehicle 200 (without human manipulation) along the reference lane change trajectory curve to a lane to be changed (e.g., the lane 402 shown in fig. 2) in response to the relevant steering control command. More specifically, the reference lane change trajectory curve can be generally decomposed into a reference longitudinal trajectory curve and a reference lateral trajectory curve. The lateral trajectory tracking system 100 includes a lane detection module 1, an inertial measurement unit 2, and a processing unit 3.
The lane detection module 1 is disposed on the vehicle 200, and includes, for example, a CCD image sensor 11 mounted on a front windshield of the vehicle 200, and an image processor 12 electrically connected to the CCD image sensor 11. The CCD image sensor 11 is used to continuously sense the images of the lane 401 at a sensing frequency (e.g., 10/sec), and the image processor 12 generates lane line data (which can include, for example, a left lane line equation and a right lane line equation) corresponding to a current time point from a plurality of images previously sensed by the CCD image sensor 11 and using a known image processing algorithm.
The Inertial Measurement Unit (Inertial Measurement Unit)2 is disposed in the vehicle 200 and includes, for example, a three-axis Gyroscope (Triaxial gyro) 21, a three-axis Accelerometer (Triaxial Accelerometer)22 and a speed sensor 23, but not limited to this example, which are used for continuously measuring the angular velocity, the acceleration and the speed of the vehicle 200, respectively, and generating and outputting a Measurement result including the measured velocity, the angular velocity and the acceleration.
For example, in the present embodiment, the output update rate of the lane detection module 1 can be designed to be 10/sec, for example, and the output update rate of the inertial measurement unit 2 can be designed to be the reciprocal of a unit time (e.g., 10ms) (e.g., 100/sec, which is ten times the output update rate of the lane detection module 1), for example.
The processing unit 3 is electrically connected to the lane detection module 1 and the inertia measurement unit 2 to receive all lane line data from the lane detection module 1 and the measurement result from the inertia measurement unit 2. The processing unit 3 is also used to connect the lane change assistance system 4 to receive the lateral trajectory profile estimated by the lane change assistance system 4 when necessary (that is to say when the vehicle 200 is to change lanes). In the present embodiment, the processing unit 3 has an arithmetic operation function and a noise filtering function.
Referring to fig. 1 to 4, a detailed description will be given of an example when a driver of the vehicle 200 wants to change from a lane 401 to a lane 402 (see fig. 2) at a current time point (hereinafter, t is given0To indicate) has activated a turn signal (not shown), how the processing unit 3 obtains a target lateral trajectory profile for application to lane change control via performing a lateral trajectory tracking method. The lateral trajectory tracking method includes the following steps 301-308 (see FIG. 3).
When the turn signal of the vehicle 200 is activated, the lane change assistance system 4 starts to operate to estimate the current time point t with respect to a reference point 201 of the vehicle 200 (e.g., the center of gravity of the vehicle 200 as shown in fig. 2)0E.g. by P in fig. 20Represented for example as a cubic curve and represented by the curve C1 of the solid line in fig. 2), and outputs the reference lane change trajectory curve C1 to the processing unit 3. Then, the processing unit 3 obtains the reference lane change trajectory curve C1 from the lane change assist system 4 in a manner of receiving from the outside (step S301).
Next, in step 302, the processing unit 3 estimates the reference point 201 of the vehicle 200 at the current time point t according to the lane line data from the lane detection module 10Position P of0Current location data.
On the other hand, in step 303, the processing unit 3 estimates the longitudinal displacement amount (for example, from S in fig. 2) of the vehicle 200 in a unit time (for example, 10ms) in the future from the measurement results (that is, the velocity, the angular velocity, and the acceleration) from the inertia measurement unit 2xIndicated by S in fig. 2), amount of lateral displacement (e.g., by S in fig. 2)yDenoted by), and an azimuth offset (e.g., denoted by ψ in fig. 2). More specifically, here, the processing unit 3 can function as a kalman filter (kalman)n Filter) to Filter out noise of the angular velocity and the acceleration by using a kalman filtering method, and then estimate a Yaw Rate (Yaw Rate) and a lateral acceleration of the vehicle 200 by using a kalman estimation method according to the filtered angular velocity and the filtered acceleration. The details of the kalman filter and the kalman estimation are well known to those skilled in the art and will not be further described herein. Finally, the processing unit 3 estimates the azimuth offset ψ and the lateral displacement amount S based on the yaw rate, the lateral acceleration, and the unit timeyAnd estimating the longitudinal displacement amount S based on the speed, the yaw rate, and the unit timex。
It is noted that the execution sequence of steps 302 and 303 is not limited.
In step 304 following steps 302 and 303, the processing unit 3 estimates the current position data and the longitudinal displacement S according to the estimated current position dataxThe lateral displacement amount SyAnd the azimuth offset ψ, and converting the reference lane change trajectory curve C1 into a future unit time point (hereinafter, denoted by t) with respect to the reference point 201 of the vehicle 200 by using a coordinate conversion method0+1Indicated below with P) of the estimated position (hereinafter, indicated with P)0+1Etc.) of the vehicle (hereinafter, indicated by C2). More specifically, as shown in FIG. 2, if the estimated position P is0+1Is located on the reference lane change trajectory curve C1 (i.e., the lateral displacement SyThe same reference lateral displacement S as obtained by the reference lane change trajectory curve C1 in the unit time in the futureyC1) The lane change trajectory curve C2 mostly overlaps the reference lane change trajectory curve C1. On the other hand, if the estimated position P is0+1When not located on the reference lane change trajectory curve C1, e.g. the estimated position P0+1On the left side of the reference lane change trajectory curve C1 (which means the amount of lateral displacement S)yLess than the reference lateral displacement SyC1) As shown in FIG. 4, or the estimated position P0+1Is located on the right side of the reference lane change trajectory curve C1 (not shown, which means the lateral displacement SyGreater than the reference lateral displacement SyC1) The lane change trajectory curve C2 would be a cubic curve different from the reference lane change trajectory curve C1 (see fig. 4). It is particularly noted that P is clearly shown in FIGS. 2 and 40And P0+1Said position P0And the estimated position P0+1The distance between is presented in a strongly exaggerated manner in fig. 2 and 4. In this case, the reference point 201 of the vehicle 200 is at the future point in time t0+1With respect to the current time point t0Can be expressed as the following equation 1:
Figure BDA0002254354240000091
after the formula 1 is subjected to inverse coordinate transformation, the following formula 2 is obtained:
Figure BDA0002254354240000092
then, x ═ g (x ', y') and y ═ h (x ', y') can be obtained from formula 2. When the reference lane change trajectory curve C1 is y1＝f1(x)＝a1x3+b1x2+c1x+d1The obtained lane change trajectory curve C2 can be expressed as the following equation 3:
h(x’,y’)＝f1(g(x’,y’))＝a2x’3+b2x’2+c2x’+d2 formula 3
Then, in step 305, the processing unit 3 decomposes the lane change trajectory curve C2 into a lateral trajectory curve and a longitudinal trajectory curve. The lateral trajectory curve is typically, for example, a cubic curve (which can be, for example, y (t) ═ at)3+bt2+ ct + d). For example, in the case of FIG. 2, the lateral trajectory curveFor example, a cubic curve 6 as shown in fig. 6.
Next, in step 306, the processing unit 3 generates a target lateral trajectory curve according to a predetermined acceleration threshold (hereinafter, denoted by a), a predetermined Jerk (Jerk) threshold (hereinafter, denoted by J), and the lateral trajectory curve by using a predetermined trapezoidal acceleration curve model, so that an absolute value of an acceleration value of the target lateral acceleration curve obtained after the target lateral trajectory curve is subjected to two differentiation processes is not greater than the predetermined acceleration threshold, and an absolute value of a Jerk value of the target lateral Jerk curve obtained after the target lateral trajectory curve is subjected to three differentiation processes is not greater than the predetermined Jerk threshold. In the present embodiment, for example, a is 3m/s2And J is 5m/s3However, this is not a limitation.
More specifically, referring to FIG. 5, step 306 includes the following substeps 51-54.
In step 51, the processing unit 3 first performs two differentiation processes on the lateral trajectory curve (e.g. curve 6 of fig. 6) to obtain a reference curve (not shown).
Then, in step 52, the processing unit 3 modifies the reference curve using a predetermined trapezoidal acceleration curve model to obtain a reference lateral acceleration curve (in a)y_ref(t). In this embodiment, the reference lateral acceleration curve has a first trapezoidal curve segment having an acceleration value of not less than zero, and a second trapezoidal curve segment connecting the first trapezoidal curve segment, the second trapezoidal curve segment having an acceleration value of not greater than zero, and the second trapezoidal curve segment is mapped to the first trapezoidal curve segment in acceleration values. For example, FIG. 7 depicts a reference lateral acceleration curve 7 (at a) corresponding to the lateral trajectory curve 6 of FIG. 6y_ref(t) including a first trapezoidal curve section 71, for example, in an isosceles trapezoid shape, and a second trapezoidal curve section 72, for example, in an inverted isosceles trapezoid shape, and the first trapezoidal curve section 71 has a value not less than zero but not more than 5m/s2And the second trapezoidal curve segment 72 has an acceleration value not greater than zero but not less than-5m/s2The acceleration value of (1).
Next, in step 53, the processing unit 3 plans a sine-like wave curve as a target acceleration curve according to the reference lateral acceleration curve, the predetermined acceleration threshold and the predetermined jerk threshold, so that the sine-like wave curve has a first curve segment with an acceleration value not less than zero and not greater than the predetermined acceleration threshold, and a second curve segment connected to the first curve segment, the second curve segment has an acceleration value not greater than zero and an absolute value not greater than the predetermined acceleration threshold, and each of the first curve segment and the two curve segments has an absolute value not greater than the predetermined jerk threshold after being subjected to a first differentiation process. For example, FIG. 8 depicts a target lateral acceleration curve 8 (which is a sine-wave-like curve and is denoted by a) corresponding to the lateral trajectory curve 6 of FIG. 6y_target(t) including, but not limited to, a first curve segment 81 and a second curve segment 82, wherein the maximum acceleration value of the first curve segment 81 is about 3m/s2And the second curve segment 82 has a minimum acceleration value of about-3 m/s2FIG. 9 is a graph showing a target lateral jerk curve 9 (in j) obtained by subjecting the target lateral acceleration curve 8 of FIG. 8 to a first differential processy_target(t) has a molecular weight of not more than 5 m/s)3(the predetermined jerk threshold) is the magnitude of the (jerk) absolute value.
Finally, in step 54, the processing unit 3 performs twice integration processing on the target lateral acceleration curve to obtain the target lateral trajectory curve.
In step 307 following step 306, the processing unit 3 generates the future time t relative to the reference point 201 of the vehicle 200 according to the longitudinal trajectory profile and the target lateral trajectory profile0+1Is estimated to be the position P0+1The target lane change trajectory curve (e.g., the dashed curve C3 of fig. 2 and 4).
Finally, in step 308, the processing unit 3 outputs the target lane change trajectory curve to the lane change assist system.
In summary, the target lateral trajectory curve planned by the lateral trajectory tracking system 100 according to the present invention is not greater than the predetermined acceleration threshold in terms of lateral acceleration and not greater than the predetermined jerk threshold in terms of lateral jerk, so that the vehicle bouncing phenomenon caused by the abrupt change of the steering control command (e.g., the lateral jerk is greater than the predetermined lateral jerk threshold or the lateral acceleration is greater than the predetermined lateral acceleration threshold) can be effectively avoided by using the target lane change trajectory curve planned by the target lateral trajectory profile. So the object of the present invention can be achieved.
The above description is only an example of the present invention, and the scope of the present invention should not be limited thereby, and the invention is still within the scope of the present invention by simple equivalent changes and modifications made according to the claims and the contents of the specification.

Claims (11)

1. A lateral trajectory tracking method for lane change control implemented by a processing unit, comprising the steps of:
(A) estimating current position data of a position of a reference point of a vehicle at a current time point based on lane line data obtained by a lane sensing module provided in the vehicle based on a plurality of images previously sensing the lane, when receiving a reference lane change trajectory curve estimated by a lane change assistance system provided in the vehicle traveling in a lane with respect to the position of the reference point of the vehicle at the current time point;
(B) estimating the longitudinal displacement, the lateral displacement and the azimuth offset of the vehicle in unit time in the future according to the speed, the angular speed and the acceleration of the vehicle measured by an inertia measuring unit arranged on the vehicle at the current time point;
(C) converting the reference lane change trajectory curve into a lane change trajectory curve of an estimated position at a future unit time point relative to the reference point of the vehicle by using a coordinate conversion mode according to the estimated current position data, the longitudinal displacement amount, the lateral displacement amount, and the azimuth offset amount;
(D) decomposing the lane change track curve into a lateral track curve and a longitudinal track curve; and
(E) and generating a target lateral track curve according to a preset acceleration threshold, a preset jerk threshold and the lateral track curve and by using a preset trapezoidal acceleration curve model, so that the absolute value of the acceleration value of the target lateral acceleration curve obtained after the target lateral track curve is subjected to twice differential processing is not greater than the preset acceleration threshold, and the absolute value of the jerk value of the target lateral jerk curve obtained after the target lateral track curve is subjected to three times differential processing is not greater than the preset jerk threshold.
2. The lateral trajectory tracking method for lane change control according to claim 1, characterized in that: the processing unit firstly filters the noise of the angular velocity and the acceleration by using a Kalman filtering mode, then estimates the yaw rate and the lateral acceleration of the vehicle according to the angular velocity and the acceleration after filtering and by using a Kalman estimation mode, estimates the azimuth offset and the lateral displacement according to the yaw rate, the lateral acceleration and the unit time, and estimates the longitudinal displacement according to the velocity, the yaw rate and the unit time.
3. The lateral trajectory tracking method for lane change control according to claim 1, characterized in that: the predetermined acceleration threshold is 3m/s2And the predetermined jerk threshold is 5m/s3。
4. The lateral trajectory tracking method for lane change control according to claim 1, wherein step (E) comprises the sub-steps of:
(E1) performing, by the processing unit, differential processing on the lateral trajectory curve twice to obtain a reference curve;
(E2) modifying, by the processing unit, the reference curve with a predetermined trapezoidal acceleration curve model to obtain a reference lateral acceleration curve, wherein the reference lateral acceleration curve has a first trapezoidal curve segment having an acceleration value of not less than zero, and a second trapezoidal curve segment connecting the first trapezoidal curve segment having an acceleration value of not more than zero, and the second trapezoidal curve segment is mapped to the first trapezoidal curve segment in acceleration values;
(E3) planning a sine-like wave curve as a target acceleration curve according to the reference lateral acceleration curve, the predetermined acceleration threshold and the predetermined jerk threshold by the processing unit, so that the sine-like wave curve has a first curve segment and a second curve segment connected with the first curve segment, wherein the first curve segment has an acceleration value not less than zero but not more than the predetermined acceleration threshold, the second curve segment has an acceleration value not more than zero and an absolute value not more than the predetermined acceleration threshold, and each of the first curve segment and the second curve segment has an absolute value not more than the predetermined jerk threshold after being subjected to a first differential processing; and
(E4) and performing twice integration processing on the target lateral acceleration curve through the processing unit to obtain the target lateral trajectory curve.
5. The method for lateral trajectory tracking for lane change control of claim 1, further comprising the step, after step (E), of:
(F) generating a target lane change trajectory curve with respect to an estimated position of the reference point of the vehicle at the future unit time point according to the longitudinal trajectory curve and the target lateral trajectory curve, and outputting the target lane change trajectory curve to the lane change assistance system.
6. A lateral trajectory tracking system for lane change control adapted for use in conjunction with a lane change assist system mounted to a vehicle traveling in a lane, comprising:
the lane detection module is arranged on the vehicle and used for continuously sensing images of the lane so as to generate lane line data corresponding to the current time point according to a plurality of previously sensed images;
an inertial measurement unit disposed on the vehicle for continuously measuring a speed, an angular velocity and an acceleration of the vehicle to generate a measurement result including the speed, the angular velocity and the acceleration; and
a processing unit electrically connected to the lane detection module and the inertia measurement unit to receive the lane line data from the lane detection module and the measurement result from the inertia measurement unit, and adapted to connect the lane change assist system, and perform the following operations when receiving a reference lane change trajectory curve estimated by the lane change assist system with respect to a position of a reference point of the vehicle at the current time point
Estimating current position data of a position of the reference point of the vehicle at the current time point based on the lane line data,
estimating the longitudinal displacement, the lateral displacement and the azimuth offset of the vehicle in the unit time in the future according to the measurement result,
converting the reference lane change trajectory curve into a lane change trajectory curve of an estimated position at a future unit time point with respect to the reference point of the vehicle using a coordinate conversion method based on the estimated current position data, the longitudinal displacement amount, the lateral displacement amount, and the azimuth offset amount,
decomposing the lane change trajectory curve into a lateral trajectory curve and a longitudinal trajectory curve, an
And generating a target lateral track curve according to a preset acceleration threshold, a preset jerk threshold and the lateral track curve and by using a preset trapezoidal acceleration curve model, so that the absolute value of the acceleration value of the target lateral acceleration curve obtained after the target lateral track curve is subjected to twice differential processing is not greater than the preset acceleration threshold, and the absolute value of the jerk value of the target lateral jerk curve obtained after the target lateral track curve is subjected to three times differential processing is not greater than the preset jerk threshold.
7. The lateral trajectory tracking system for lane change control of claim 6, wherein: the processing unit firstly filters the noise of the angular velocity and the acceleration by using a Kalman filtering mode, then estimates the yaw rate and the lateral acceleration of the vehicle according to the angular velocity and the acceleration after filtering and by using a Kalman estimation mode, estimates the azimuth offset and the lateral displacement according to the yaw rate, the lateral acceleration and the unit time, and estimates the longitudinal displacement according to the velocity, the yaw rate and the unit time.
8. The lateral trajectory tracking system for lane change control of claim 6, wherein the inertial measurement unit comprises:
a gyroscope operative to sense the angular velocity of the vehicle;
an accelerometer operative to sense the acceleration of the vehicle; and
a speed sensor operative to sense the speed of the vehicle.
9. The lateral trajectory tracking system for lane change control of claim 6, wherein: the predetermined acceleration threshold is 3m/s2And the predetermined jerk threshold is 5m/s3。
10. The lateral trajectory tracking system for lane change control of claim 6, wherein the processing unit performs the following operations:
performing differential processing on the lateral track curve twice to obtain a reference curve;
modifying the reference curve with a predetermined trapezoidal acceleration curve model to obtain a reference lateral acceleration curve, wherein the reference lateral acceleration curve has a first trapezoidal curve segment with an acceleration value of not less than zero, and a second trapezoidal curve segment connecting the first trapezoidal curve segment with an acceleration value of not more than zero, and the second trapezoidal curve segment is mapped to the first trapezoidal curve segment in acceleration values;
according to the reference lateral acceleration curve, the preset acceleration threshold and the preset jerk threshold, a sine-wave-like curve serving as a target acceleration curve is planned, so that the sine-wave-like curve is provided with a first curve section and a second curve section connected with the first curve section, wherein the first curve section is provided with an acceleration value which is not less than zero but not more than the preset acceleration threshold, the second curve section is provided with an acceleration value which is not more than zero and the absolute value of the second curve section is not more than the preset acceleration threshold, and each of the first curve section and the second curve section is subjected to one-time differential processing and then is provided with an absolute value which is not more than the preset jerk threshold; and
and performing twice integration processing on the target lateral acceleration curve to obtain the target lateral trajectory curve.
11. The lateral trajectory tracking system for lane change control of claim 6, wherein: the processing unit generates a target lane change trajectory curve of an estimated position at the future unit time point relative to the reference point of the vehicle according to the longitudinal trajectory curve and the target lateral trajectory curve, and outputs the target lane change trajectory curve to the lane change assistance system.
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