CN113911112B - Lane departure assisting method and system based on curve fitting - Google Patents
Lane departure assisting method and system based on curve fitting Download PDFInfo
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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
- B60W30/10—Path keeping
- B60W30/12—Lane keeping
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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
- B60W50/00—Details of control systems for road vehicle drive control not related to the control of a particular sub-unit, e.g. process diagnostic or vehicle driver interfaces
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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
- B60W50/00—Details of control systems for road vehicle drive control not related to the control of a particular sub-unit, e.g. process diagnostic or vehicle driver interfaces
- B60W50/08—Interaction between the driver and the control system
- B60W50/14—Means for informing the driver, warning the driver or prompting a driver intervention
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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
- B60W50/00—Details of control systems for road vehicle drive control not related to the control of a particular sub-unit, e.g. process diagnostic or vehicle driver interfaces
- B60W2050/0001—Details of the control system
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- 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
- B60W50/00—Details of control systems for road vehicle drive control not related to the control of a particular sub-unit, e.g. process diagnostic or vehicle driver interfaces
- B60W2050/0001—Details of the control system
- B60W2050/0019—Control system elements or transfer functions
- B60W2050/002—Integrating means
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- B—PERFORMING OPERATIONS; TRANSPORTING
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- B60W50/00—Details of control systems for road vehicle drive control not related to the control of a particular sub-unit, e.g. process diagnostic or vehicle driver interfaces
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- B60W50/14—Means for informing the driver, warning the driver or prompting a driver intervention
- B60W2050/143—Alarm means
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- B60W2420/00—Indexing codes relating to the type of sensors based on the principle of their operation
- B60W2420/40—Photo, light or radio wave sensitive means, e.g. infrared sensors
- B60W2420/403—Image sensing, e.g. optical camera
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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
- B60W2420/00—Indexing codes relating to the type of sensors based on the principle of their operation
- B60W2420/40—Photo, light or radio wave sensitive means, e.g. infrared sensors
- B60W2420/408—Radar; Laser, e.g. lidar
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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
- B60W2552/00—Input parameters relating to infrastructure
- B60W2552/50—Barriers
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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
- B60W2552/00—Input parameters relating to infrastructure
- B60W2552/53—Road markings, e.g. lane marker or crosswalk
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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Abstract
Aiming at the problem that a planning unit is lack in a lane departure auxiliary system in the prior art, control parameters are easy to be unsmooth, so that the experience comfort of passengers is poor; the lane departure auxiliary system based on curve fitting is characterized in that a planning unit is additionally arranged on an information processing module in the system, the planning unit adopts a lane departure auxiliary method based on curve fitting, namely, a smoothly-changing deviation rectifying track curve is planned by adopting a Bezier curve fitting mode, and deviation rectifying track information is sent to a control module for smooth and stable vehicle deviation rectifying control, so that smooth change of control parameters is ensured, riding comfort is effectively improved, and the processing process is simplified.
Description
Technical Field
The invention relates to the field of intelligent driving of vehicles, in particular to a lane departure assisting method and system based on curve fitting.
Background
The LKA is used for assisting a driver to keep the vehicle running in a lane line, is a lateral motion control ADAS function developed in the lane departure warning LDW function, mainly by recognizing the position of the vehicle relative to the center of the lane through an environmental sensor, and if the driver unintentionally deviates from the lane, giving a warning to the driver or returning the vehicle to the lane through automatic steering intervention. The LKA mainly comprises an information acquisition module, an information processing module and a control module, and when a vehicle deviates from a lane during the working of the system, a driver receives warning information of lane departure, and at the moment, the system selects to control a steering system to realize automatic driving. The lane departure warning LDW is used for sending out warning to a driver in the modes of sound, vision, vibration and the like when the vehicle unconsciously departs from the lane; lane departure prevention LDP is an extension of the LDW function to correct the vehicle position by applying appropriate steering interventions immediately before driving away when an unintentional departure of the vehicle from the lane occurs. In the prior art, the yaw rate is obtained through a sensor (namely, the yaw rate is obtained through calculation of various sensor information of the vehicle), and the lack of a planning unit easily causes unsmooth control parameters, so that comfort is poor, and passengers experience bad; in addition, the yaw angle calculation is assisted by adopting a Kalman filtering algorithm in the prior art, so that the problems of complicated technology, complicated parameter adjustment and the like exist, and the weight setting is also complicated according to various conditions in the processing process. For example, chinese patent grant bulletin number: CN108327717B discloses a lane departure assistance system for man-machine co-driving and a lane departure assistance method thereof, the lane departure assistance system comprising: the auxiliary decision-making module is used for judging whether the vehicle deviates from the lane or not and coordinating the control right of the driver and the lane departure auxiliary system to the vehicle when the vehicle is judged to deviate from the lane; the controller module is used for actively correcting the vehicle posture when the vehicle deviates from the lane, ensuring that the vehicle always runs near the center line of the lane and ensuring the driving safety; and the execution module is used for executing the control information of the controller module and completing lane departure assistance. According to the lane departure auxiliary system for the man-machine co-driving, the vehicle posture is actively corrected when the vehicle deviates from the lane, so that the vehicle is ensured to always run near the center line of the lane, and the driving safety is ensured, but the lane departure auxiliary system lacks a planning unit, so that control parameters are not smooth easily, and the experience comfort of passengers is poor.
Disclosure of Invention
Aiming at the problem that a lane departure auxiliary system in the prior art lacks a planning unit, the control parameters are easy to be unsmooth, so that the comfort of passengers is poor; the prior art is complicated, and the processing process is complex, and the lane departure auxiliary system based on curve fitting is provided, a planning unit is arranged in the system, the planning unit adopts a lane departure auxiliary method based on curve fitting, a smooth deviation rectifying track curve is planned by a Bezier curve fitting mode, and deviation rectifying track information is sent to a control module for smooth and stable vehicle control, so that smooth change of control parameters is ensured, riding comfort is effectively improved, and the processing process is simplified.
In order to achieve the above purpose, the present invention adopts the following technical scheme:
a lane departure assistance method based on curve fitting, comprising the steps of: step S1), discretizing a target track; step S2), smoothing the target track; step S3), lane departure detection, if departure, executing step S4; if not, directly converting the detection information into interface information and outputting the interface information; step S4), calculating a starting point and an ending point of the fitted curve; step S5) adopting a Bezier curve fitting mode to calculate a smooth track of the curve between the starting point and the end point, and obtaining a deviation rectifying track curve; and S6) converting the deviation rectifying track curve information obtained in the step S5, and outputting interface information obtained by conversion. In the lane departure auxiliary system in the prior art, the yaw rate is obtained through a sensor (namely, the yaw rate is obtained through calculation of various sensor information of the vehicle), and the lack of a planning unit easily causes unsmooth control parameters, so that the comfort is poor, and the experience of passengers is poor; in addition, the yaw angle calculation is assisted by adopting a Kalman filtering algorithm in the prior art, so that the problems of complicated technology, complicated parameter adjustment and the like exist, and the weight setting is also complicated according to various conditions in the processing process. Therefore, the invention provides a lane departure auxiliary method based on curve fitting, which adopts a Bezier curve fitting mode to plan a smooth deviation rectifying track curve, and then transmits deviation rectifying track information to a control module of a lane departure auxiliary system to carry out smooth and stable vehicle control, thereby ensuring smooth change of control parameters, effectively improving riding comfort and simplifying processing procedures. The specific process is as follows: firstly, calculating according to requirements to obtain a target track, wherein the requirements are various, for example, correction is performed when a vehicle drives away from a left lane line, the vehicle is controlled within a specific distance value from the left lane line, the virtual target track reference line is parallel to the lane line, and then discretization processing is performed on the target track reference line; then smoothing the obtained discretized target track reference line by adopting a spline curve fitting mode; detecting lane departure data, including the distance between the vehicle and the lane line and the vehicle driving-out time, comparing the detected distance between the vehicle and the lane line with a set distance threshold value, comparing the vehicle driving-out time with a set time threshold value, judging whether the vehicle deviates from the lane according to the comparison result, and if not, directly converting the detected data into interface information and outputting the interface information to a control module of a lane departure auxiliary system; if so, calculating to obtain a smooth variation deviation rectifying track by adopting a Bezier curve fitting mode, firstly calculating a starting point and an ending point of the Bezier curve, wherein the starting point is a vehicle body pose point at the current moment, the ending point is a certain point on a target track, the two points comprise position, speed, acceleration and jerk information, and then carrying out derivative or integral operation on the Bezier curve to obtain a smooth variation position, speed, acceleration and jerk curve; and finally, converting smooth deviation rectifying track curve information obtained through planning processing in a Bezier curve fitting mode according to a contracted interface protocol, and transmitting the interface information obtained through conversion to a control module. The control module judges whether to carry out deviation rectifying operation according to the received interface information, if so, the control alarm unit alarms, the steering control unit is controlled to carry out vehicle steering intervention according to the smooth deviation rectifying track curve, and the deviation rectifying track curve is subjected to planning treatment, so that the steering deviation rectifying control is stable, the passenger comfort is improved, and the whole treatment process is simple.
Preferably, in the step S2, the discretized target track reference line obtained in the step S1 is smoothed by adopting a spline curve fitting method. According to the invention, a target track is obtained by calculation according to requirements, the virtual target track reference line is parallel to the lane line, then discretization processing is carried out on the target track reference line, and then smoothing processing is carried out on the obtained discretization target track reference line by adopting a spline curve fitting mode, so that a smoothly-changed target track curve is obtained.
Preferably, the specific process of the step S3 includes the following steps: step A1), detecting and obtaining the distance between a vehicle and a lane line and the time when the vehicle leaves the lane; step A2) judging whether the vehicle deviates from the lane or not by comparing the distance between the vehicle and the lane line with a set distance threshold value and the time for the vehicle to leave the lane with a set time threshold value, and if so, executing step S4; if not, directly converting the detection information into interface information and outputting the interface information. The invention detects lane departure data, comprising the distance between a vehicle and a lane line and the time for the vehicle to leave the lane, compares the detected distance between the vehicle and the lane line with a set distance threshold value, compares the time for the vehicle to leave the lane with a set time threshold value, judges whether the vehicle deviates from the lane according to the comparison result, and directly converts the detected data into interface information and outputs the interface information to a control module of a lane departure auxiliary system if the vehicle does not deviate from the lane; and if the deviation is detected, calculating by adopting a Bezier curve fitting mode to obtain a deviation rectifying track curve with smooth change.
Preferably, in the step S4, the starting point is a vehicle body pose point at the current time, and the end point is a point on the target track. These two points contain position, velocity, acceleration, jerk information. The end point is a point on the target track determined according to specific requirements.
Preferably, in the step S5, the starting point and the end point obtained by the calculation in the step S4 are used as two end points of a Bezier curve (Bezier curve), and derivative or integral calculation is performed on the Bezier curve to obtain a smoothly-varying position curve, a smoothly-varying velocity curve, a smoothly-varying acceleration curve and a smoothly-varying jerk curve. The invention adopts Bezier curve fitting mode to obtain smooth deviation rectifying track curve, and obtains smooth position curve, speed curve, acceleration curve and jerk curve by deriving or integrating track curve.
Preferably, in the step S5, the vehicle state at each time is expressed as:
where x is a vehicle state quantity, p is a vehicle position, v is a vehicle speed, a is a vehicle acceleration, and j is a vehicle jerk. When Bezier curve fitting is carried out to obtain a deviation rectifying track curve, the vehicle state at each moment needs to be defined first.
Preferably, in step S5, the deviation rectifying trajectory curve is a segment curve C n (t) represents defining a segmentation curve C n (t) is:
wherein ,when t is E [0, t e ]The piecewise curve would then need to meet the following constraints: c (C) k (t) is a continuous function; segment curve starting point C n (0)＝x 0 Segment curve endpoint C n (t e )＝x e . Segment curve C n (t) C in the constraint to be satisfied k (t) is a continuous function, i.e. +.>As a continuous function.
Preferably, the calculation formula of the bezier curve is:
wherein d is Bessel order; k is a curve segment index value; s is the time normalized quantity, s is more than or equal to 0 and less than or equal to 1; b (B) i,d (s) is a Bernstein basis function (Bernstein basis polynomials), defined as follows:
wherein ,from->It can be seen that each segment of the curve is a d-order bezier curve, which is a smooth curve, and that the derivative or integral calculation of the curve can be used to obtain smoothly varying position, velocity, acceleration and jerk curves for smooth and comfortable vehicle control.
The lane departure auxiliary system based on curve fitting comprises an information acquisition module, an information processing module and a control module, wherein the information acquisition module, the information processing module and the control module are sequentially connected, the information acquisition module comprises a lane line, an obstacle information acquisition unit and a vehicle body information acquisition unit, the information processing module comprises a data fusion unit and a data processing unit, the control module comprises an alarm unit and a steering control unit, the information processing module further comprises a planning unit, the planning unit adopts the lane departure auxiliary method based on curve fitting, and the planning unit takes interface information obtained by converting step S3 or step S6 as input of the control module according to an interface protocol agreed with the control module. The invention provides a lane departure auxiliary system based on curve fitting, which is characterized in that a planning unit is additionally arranged in an existing lane departure auxiliary system (LKA) information processing module, and deviation correction data transmitted to a control module is subjected to planning smoothing processing of the planning unit, so that the control parameter is smoothly changed, the control module can perform stable vehicle control, the comfort of passengers is effectively improved, and the processing process is simplified. The specific process is as follows: the vehicle deviates from lane line, obstacle information acquisition unit of the information acquisition module of the auxiliary system and gathers lane line, obstacle information through the sensor such as the radar, camera, etc., the body information acquisition unit gathers the body information through CAN bus, then the information acquisition module transmits the information gathered to the information processing module, after processing through data fusion unit and data processing unit in the information processing module, plan smooth processing through planning unit, namely calculate and obtain the deviation rectifying track curve of smooth change by adopting Bezier curve fitting mode, then calculate deviation rectifying track curve derivation or integral, obtain smooth change position, speed, acceleration and jerk curve, then according to the interface agreement agreed with the control module, convert the curve information, interface information obtained by conversion is regarded as the input of the control module, the control module judges whether to correct the operation according to interface information obtained, if need correcting the operation, control alarm unit is reported to police, in order to prompt the driver; the steering control unit is controlled to perform automatic steering intervention, and the design ensures that the vehicle deviation correcting steering control is efficient, stable and comfortable.
Therefore, the invention has the advantages that: the correction track curve is calculated and obtained by adopting a Bezier curve fitting mode, and the correction track curve is subjected to planning treatment, so that the control parameters are smoothly changed, the control module can perform stable and comfortable vehicle correction steering control, the comfort of passengers is effectively improved, and the whole treatment process is simple.
Drawings
Fig. 1 is a schematic structural diagram of a lane departure assistance method based on curve fitting in an embodiment of the present invention.
Fig. 2 is a schematic structural diagram of a lane departure assistance system based on curve fitting according to an embodiment of the present invention.
1. The vehicle body information acquisition system comprises an information acquisition module 11, lane lines, an obstacle information acquisition unit 12, a vehicle body information acquisition unit 2, an information processing module 21, a data fusion unit 22, a data processing unit 23, a planning unit 3, a control module 31, an alarm unit 32 and a steering control unit.
Detailed Description
The invention is further described below with reference to the drawings and detailed description.
As shown in fig. 1, a lane departure assistance method based on curve fitting includes the following steps: step S1), discretizing a target track; step S2), smoothing the target track; step S3), lane departure detection, if departure, executing step S4; if not, directly converting the detection information into interface information and outputting the interface information; step S4), calculating a starting point and an ending point of the fitted curve; step S5) adopting a Bezier curve fitting mode to calculate a smooth track of the curve between the starting point and the end point, and obtaining a deviation rectifying track curve; and S6) converting the deviation rectifying track curve information obtained in the step S5, and outputting interface information obtained by conversion. The invention provides a lane departure auxiliary method based on curve fitting, which adopts a Bezier curve fitting mode to plan a smooth deviation rectifying track curve, and then transmits deviation rectifying track information to a control module 3 of a lane departure auxiliary system to carry out smooth and stable vehicle control, so as to ensure smooth change of control parameters. The specific process is as follows: firstly, calculating according to requirements to obtain a target track, wherein the requirements are various, for example, correction is performed when a vehicle drives away from a left lane line, the vehicle is controlled within a specific distance value from the left lane line, the virtual target track reference line is parallel to the lane line, and then discretization processing is performed on the target track reference line; then smoothing the obtained discretized target track reference line by adopting a spline curve fitting mode; then detecting lane departure data, comprising the distance between the vehicle and the lane line and the vehicle driving-out time, comparing the detected distance between the vehicle and the lane line with a set distance threshold value, comparing the vehicle driving-out time with a set time threshold value, judging whether the vehicle deviates from the lane according to the comparison result, and if not, directly converting the detected data into interface information and outputting the interface information to a control module 3 of the lane departure auxiliary system; if so, calculating to obtain a smooth variation deviation rectifying track by adopting a Bezier curve fitting mode, firstly calculating a starting point and an ending point of the Bezier curve, wherein the starting point is a vehicle body pose point at the current moment, the ending point is a certain point on a target track, the two points comprise position, speed, acceleration and jerk information, and then carrying out derivative or integral operation on the Bezier curve to obtain a smooth variation position, speed, acceleration and jerk curve; and finally, converting the smooth deviation rectifying track curve information obtained through planning processing in a Bezier curve fitting mode according to a contracted interface protocol, and transmitting the interface information obtained through conversion to the control module 3. The control module 3 judges whether to perform deviation rectifying operation according to the received interface information, if so, the control alarm unit 31 alarms, and the steering control unit 32 performs vehicle steering intervention according to the smooth deviation rectifying track curve. Besides Bezier curve fitting mode, the invention can also perform curve fitting by a polynomial mode.
In step S5, the vehicle state at each time is expressed as:
where x is a vehicle state quantity, p is a vehicle position, v is a vehicle speed, a is a vehicle acceleration, and j is a vehicle jerk. When Bezier curve fitting is carried out to obtain a deviation rectifying track curve, the vehicle state at each moment needs to be defined first.
In step S5, a segment curve C for correcting the track curve n (t) represents defining a segmentation curve C n (t) is:
wherein ,when t is E [0, t e ]The piecewise curve would then need to meet the following constraints: c (C) k (t) is a continuous function; segment curve starting point C n (0)＝x 0 Segment curve endpoint C n (t e )＝x e . Segment curve C n (t) C in the constraint to be satisfied k (t) is a continuous function, i.e. +.>As a continuous function.
The calculation formula of the Bezier curve is as follows:
wherein d is Bessel order; k is a curve segment index value; s is the time normalized quantity, s is more than or equal to 0 and less than or equal to 1; b (B) i,d (s) is a Bernstein basis function (Bernstein basis polynomials), defined as follows:
wherein ,from->It can be seen that each segment of the curve is a d-order bezier curve, which is a smooth curve, and that the derivative or integral calculation of the curve can be used to obtain smoothly varying position, velocity, acceleration and jerk curves for smooth and comfortable vehicle control.
As shown in fig. 2, a lane departure assistance system based on curve fitting includes an information acquisition module 1, an information processing module 2 and a control module 3, where the information acquisition module 1, the information processing module 2 and the control module 3 are sequentially connected, the information acquisition module 1 includes a lane line, an obstacle information acquisition unit 11 and a vehicle body information acquisition unit 12, the information processing module 2 includes a data fusion unit 21 and a data processing unit 22, the control module 3 includes an alarm unit 31 and a steering control unit 32, the information processing module 2 further includes a planning unit 23, the planning unit 23 adopts the lane departure assistance method based on curve fitting, and the planning unit 23 uses interface information obtained by converting in step S3 or step S6 as an input of the control module 3 according to an interface protocol agreed with the control module 3. The invention provides a lane departure auxiliary system based on curve fitting, wherein a planning unit 23 is additionally arranged in an existing lane departure auxiliary system (LKA) information processing module 2, and as deviation correction data transmitted to a control module 3 is subjected to planning smoothing processing of the planning unit 23, control parameters are smoothly changed, so that the control module 3 can perform stable vehicle control. The specific process is as follows: the vehicle deviates from lane line, obstacle information acquisition unit 11 of the information acquisition module 1 of the auxiliary system and gathers lane line, obstacle information through sensors such as radar, camera, etc., the body information acquisition unit 12 gathers the body information through CAN bus, then the information acquisition module 1 transmits the information gathered to the information processing module 2, after processing through data fusion unit 21 and data processing unit 22 in the information processing module 2, plan smooth processing through planning unit 23, namely calculate and obtain the deviation rectifying track curve of smooth change by adopting Bezier curve fitting mode, then calculate and calculate the deviation rectifying track curve to obtain position, speed, acceleration and jerk curve of smooth change, then according to the interface protocol agreed with control module 3, convert the curve information, interface information obtained by conversion is regarded as the input of control module 3, control module 3 judges whether to correct the operation according to the interface information obtained, if need to correct the operation, then control the alarm unit 31 is reported to give an alarm, in order to prompt the driver; the steering control unit 32 is controlled to perform an automatic steering intervention.
Claims (8)
1. A lane departure assistance method based on curve fitting, comprising the steps of:
step S1: discretizing a target track;
step S2: smoothing the target track;
step S3: detecting lane departure, if departure, executing step S4; if not, directly converting the detection information into interface information and outputting the interface information;
step S4: calculating a starting point and an ending point of a fitting curve;
step S5: adopting a Bezier curve fitting mode to calculate a smooth track of the curve between the starting point and the end point, and obtaining a deviation rectifying track curve;
step S6: converting the deviation rectifying track curve information obtained in the step S5, and outputting interface information obtained by conversion;
in step S5, the correction trajectory curve is segmented into curve C n (t) represents defining a segmentation curve C n (t) is:
wherein ,when t is E [0, t e ]The piecewise curve would then need to meet the following constraints:
C k (t)as a continuous function; segment curve starting point C n (0)＝x 0 Segment curve endpoint C n (t e )＝x e ；
Respectively representing the vehicle position, the vehicle speed, the vehicle acceleration and the vehicle jerk after Bezier curve fitting; />Respectively representing a vehicle position curve, a vehicle speed curve, a vehicle acceleration curve and a vehicle jerk curve after Bezier curve fitting; τ 1 、τ 2 ……τ n Respectively represent the segment curves C n The time end point corresponding to each segment in (t), t e Representing a piecewise curve C n (t) a corresponding time endpoint.
2. The lane departure assistance method based on curve fitting according to claim 1, wherein in step S2, the discretized target trajectory reference line obtained in step S1 is smoothed by spline curve fitting.
3. The lane departure assistance method based on curve fitting according to claim 1, wherein the specific process of step S3 comprises the steps of:
step A1: detecting and acquiring the distance between a vehicle and a lane line and the time for the vehicle to leave the lane;
step A2: judging whether the vehicle deviates from the lane or not by comparing the distance between the vehicle and the lane line with a set distance threshold value and comparing the time for the vehicle to leave the lane with a set time threshold value, and if so, executing the step S4; if not, directly converting the detection information into interface information and outputting the interface information.
4. The lane departure assistance method based on curve fitting according to claim 1, wherein in the step S4, the starting point is a vehicle body pose point at the current moment, and the ending point is a point on the target track.
5. The lane departure assistance method according to claim 4, wherein in the step S5, the starting point and the end point obtained by the calculation in the step S4 are used as two end points of a bezier curve, and the bezier curve is subjected to derivative or integral calculation to obtain a smoothly varying position curve, a smoothly varying velocity curve, a smoothly varying acceleration curve and a smoothly varying jerk curve.
6. The lane departure assistance method based on curve fitting according to claim 1 or 5, wherein in step S5, the vehicle state at each moment is expressed as:
where x is a vehicle state quantity, p is a vehicle position, v is a vehicle speed, a is a vehicle acceleration, and j is a vehicle jerk.
7. The lane departure assistance method based on curve fitting according to claim 5, wherein the calculation formula of the bezier curve is:
wherein d is Bessel order; k is a curve segment index value; s is the time normalized quantity, s is more than or equal to 0 and less than or equal to 1; b (B) i，d (s) is a Bernstein basis function defined as follows:
wherein ,
8. the lane departure auxiliary system based on curve fitting comprises an information acquisition module, an information processing module and a control module, wherein the information acquisition module, the information processing module and the control module are sequentially connected, the information acquisition module comprises a lane line, an obstacle information acquisition unit and a vehicle body information acquisition unit, the information processing module comprises a data fusion unit and a data processing unit, and the control module comprises an alarm unit and a steering control unit.
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