CN113978467A - Vehicle automatic lane changing control method based on sine function - Google Patents

Vehicle automatic lane changing control method based on sine function Download PDF

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CN113978467A
CN113978467A CN202111263383.8A CN202111263383A CN113978467A CN 113978467 A CN113978467 A CN 113978467A CN 202111263383 A CN202111263383 A CN 202111263383A CN 113978467 A CN113978467 A CN 113978467A
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vehicle
lane
distance
speed
longitudinal
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CN113978467B (en
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罗华平
刘卫东
沈凯
李甜甜
王爱春
黄少堂
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Jiangling Motors Corp Ltd
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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
    • 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
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00—Road transport of goods or passengers
    • Y02T10/10—Internal combustion engine [ICE] based vehicles
    • Y02T10/40—Engine management systems

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  • Transportation (AREA)
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Abstract

The invention relates to the technical field of automotive electronics, in particular to a vehicle automatic lane changing control method based on a sine function. The method is based on the starting point that the angle change of the steering wheel and the change of the vehicle steering tend to be consistent and approximate to S shape in the process of changing the lane of the driver to the left and then returning the steering wheel to the right in the actual driving working condition, and the automatic lane changing control method based on the sine function is designed. The invention measures the information of the front vehicle, the information of the side and rear vehicles, the lane information and the like in real time through the distance sensor and the vision sensor, then plans a proper driving track based on the control method of the invention, dynamically corrects in real time according to the driving environment, and finally realizes safe and comfortable lane changing.

Description

Vehicle automatic lane changing control method based on sine function
Technical Field
The invention relates to the technical field of automotive electronics, in particular to a vehicle automatic lane changing control method based on a sine function.
Background
Information technologies represented by high-precision sensors, high-computing-power chips, internet of things, cloud computing, big data and artificial intelligence are widely applied at present, the intelligent development of the society is accelerated, the intelligent progress of the automobile traffic field evolves along with the intelligent progress, and ADAS/AD (advanced driver assistance system/automatic driving) is a key innovation field of the automobile industry.
In the process of the evolution of ADAS (advanced driver assistance system) to AD (automatic driving), the deep coupling of the transverse direction and the longitudinal direction is the basis of the realization of high-order functions, and the automatic lane-changing Assistance (ALC) is one of specific applications.
At present, most of automatic lane changing Auxiliary (ALC) implementation strategies, such as constant speed deviation lane changing, arc lane changing, trapezoidal acceleration lane changing and the like, do not accord with actual driving habits, are poor in track smoothness and are not friendly to experience; the S-type function lane changing strategy has large calculation amount and special treatment is needed for cut-in and cut-out; the polynomial function lane changing strategy has large calculation amount and complex boundary condition setting. Accordingly, the present patent contemplates an automatic lane change Assist (ALC) implementation strategy based on a sinusoidal function to eliminate or ameliorate the disadvantages of the aforementioned strategies.
The automatic lane change Assistant (ALC) implementation strategy related to the patent measures information (distance, speed) of vehicles in front, information of vehicles in back and side, lane information and the like in real time through a distance sensor (such as a radar) and a vision sensor (such as a camera), then plans out a proper driving track based on the strategy of the patent, dynamically corrects in real time according to driving environment, and finally realizes safe and comfortable lane change.
Disclosure of Invention
The invention aims to overcome the defects of the prior art, adapt to the practical requirements and provide a vehicle automatic lane changing control method based on a sine function.
In order to realize the purpose of the invention, the invention adopts the following technical scheme:
a vehicle automatic lane changing control method based on a sine function comprises the following steps:
s1, building a basic model:
in the actual driving working condition, when a driver changes lane to the left, the steering wheel is controlled to turn left firstly and then return to the right, and in the process, the angle change of the steering wheel is consistent with the steering change of the vehicle in a trend way and is approximate to an S shape;
s11, basic track model: taking a sine function as a vehicle running track model,
y ═ sin (x) x ∈ [ -pi/2, pi/2 ] (formula 1);
the first derivative of the equation 1 is,
Figure BDA0003326275680000021
the formula calculates each slope on the sine curve;
s12, according to the track model after the deformation of the real environment:
the base model is subjected to extended deformation to cover the key parameters as follows:
y ═ Asin (ω x + θ) + B (formula 3)
Wherein A is the amplitude of the sine function, SLW is defined as the width of the lane, LLW is the width of the left lane, and the amplitude of the sine function
Figure BDA0003326275680000022
Taking the vehicle running direction as a longitudinal direction;
y is the transverse distance in the lane changing process of the vehicle, and when lane changing is started, y is 0;
x is the longitudinal distance in the lane changing process of the vehicle and is consistent with the advancing direction, and when lane changing is started, x is 0;
the distance of the vehicle track projection on the X axis is Dmax, and the Dmax is V X T which is the maximum longitudinal distance required for completing lane changing;
omega is a conversion coefficient, the longitudinal distance of the vehicle in the X-axis direction is taken as a parameter (X), the sine function is substituted, and a formula is required
Figure BDA0003326275680000023
Conversion to an angle, i.e.
Figure BDA0003326275680000024
B is equal to a, the sin curve translates a along the positive axis Y, and when the lane change is started, Y is equal to 0;
theta is-pi/2, the sin curve is shifted pi/2 along the positive X axis, and X is 0 when the lane change is started;
the first derivative of equation (3) is: y ═ a ω cos (ω x + θ) (formula 4)
S2. constraint conditions
S21, setting lane changing speed:
current vehicle speed vxGreater than lane change enabling vehicle speed VenableAnd stably following the preceding vehicle, and the speed difference DeltaV from the preceding vehicle<ΔVthrAnd a difference Δ D between the safety distance and the safety distance of the preceding vehicle<ΔDthrFor a period of time t, t is more than or equal to 3s, the system will use the current speed vxStarting lane changing as a longitudinal vehicle speed, and solving an actual vehicle speed v by a sine function in the lane changing process; wherein, is Δ VthrFor maximum value of speed difference with the preceding vehicle when starting automatic lane change, Δ DthrThe maximum value of the safety distance between the front vehicle and the front vehicle when the automatic lane change is started;
s22, maximum longitudinal distance D generated by lane changingmax：
Lane change completion time TendWith the desired longitudinal vehicle speed vxThe product being the maximum longitudinal distance D resulting from a lane changemaxI.e. by
Dmax＝vx×TendThe sine function variable x is the [0, D ]max]；
Wherein, the lane change completion time Tend5-8 seconds as standard quantity;
s23, maximum slope k of lane change steering trackmax：
kmaxThe upper limit value k is set for different speed intervalslimitWhen k ismax>klimitForbidding lane change;
s24, the lane line and the left lane line of the vehicle can be seen, the width belongs to (3.75m + delta e), and the curvature radius is larger than a set threshold value Lmax_radius；
S25, a left lane is provided, and lane changing is allowed when no vehicle exists in front or the distance between a front left vehicle and the vehicle meets the time interval of a safe workshop;
the time-distance algorithm of the workshop is Dw＝Th*Vss-K*(Vf-Vs)+D0，
Wherein D isWThe distance between the vehicles is the current vehicle-to-vehicle distance, namely the distance between the vehicle in front of the vehicle or on the left or in front of the vehicle and the vehicle;
Vsthe vehicle speed is the vehicle speed;
Ththe time interval is the time interval between vehicles, namely the time between the vehicle and the vehicle in front or on the left or in front of the left, namely the time required for reaching the current position of the vehicle in front or on the left or in front of the left at the current speed of the vehicle.
VfThe vehicle speed is equal to the vehicle speed of the front vehicle;
D0the minimum safe distance is a standard quantity; k is an adjustment coefficient and is a standard quantity;
s26, a left lane, no vehicle behind or behind the left lane or the pre-collision time between the left rear vehicle and the vehicle is larger than a preset threshold value RCTTTCAllowing lane change; RCT (Radar Cross section)TTCIs a standard quantity;
if the above conditions S21-S26 are satisfied, the process proceeds to step S3 to start lane changing;
s3, assuming that the whole working condition is an ideal state without loss, and the longitudinal speed v of the vehiclexThe constant state can be obtained, namely the T +1 state and the required control quantity can be deduced according to the time state of T by combining a sine function;
at time T, the longitudinal speed is vxt＝vxLongitudinal distance XtWhen T +1 is expected, the longitudinal distance and the lateral distance:
Xt+1＝Xt+vxt*ΔT (5)，
Yt+1＝Asin(ω*Xt+1+θ)+B (6)
when equation (6) is substituted for equation (4) to obtain T +1, the tangent slope of the sinusoidal curve, i.e., the tangent slope of the vehicle-form trajectory:
Figure BDA0003326275680000031
further, the tangent and X can be derivedAngle of axes, i.e. yaw angle gamma at time T +1t+1：
Figure BDA0003326275680000032
Has been set at a constant longitudinal velocity vxActual vehicle speed vrDecomposed into longitudinal vehicle speed v along the X-axisxAnd a transverse vehicle speed v along the Y axisyPolicy requirement v throughout the lane change processxConstant, then vrVehicle speed (vr) at time T +1 which changes with the change of yaw anglet+1) Comprises the following steps:
Figure BDA0003326275680000033
further, the speed control amount ACC can be derived as follows:
Figure BDA0003326275680000034
vrtthe vehicle speed at time T;
Δγ＝γt+1-γtwherein γ istIs the yaw angle of the vehicle at time T,
Figure BDA0003326275680000041
namely, it is
Figure BDA0003326275680000042
Delta is a deflection angle of a steering wheel, and L is a vehicle wheelbase;
time T +1, steering wheel angle: and obtaining the steering control quantity by using the S-map (delta).
The method also comprises the following compensation and correction steps:
at time T, the current transverse distance gamma r is obtained according to the lane line informationtWhile the longitudinal distance is derived from the arcsine function:
Figure BDA0003326275680000043
from equation (5), the longitudinal distance Xp at time T-1 can be expectedtCombining equation (10) to obtain the longitudinal distance error Δ X ═ Xrt-Xpt)。
When X is presenthth>ΔX＝(Xrt-Xpt)>XlthWhen the operation is needed, compensation operation is needed;
Xlthis a error threshold; xhthEffective error threshold when Δ X>XhthThe error can be considered as unreliable;
to compensate for Δ X, it is necessary that T be to T +1, and the expected longitudinal displacement should be Δ Xt+1＝ΔX+vxt*ΔT，
Deriving the required longitudinal speed:
Figure BDA0003326275680000044
the new speed control amount ACC and the new steering control amount S are obtained by combining the formula (11) with the formula (7), the formula (8), and the formula (9).
The invention has the beneficial effects that:
the method comprises the steps of measuring information (distance and speed) of vehicles in front, information of vehicles coming from the side and the rear, lane information and the like in real time through a distance sensor (such as a radar) and a vision sensor (such as a camera), planning a proper driving track based on the control method of the patent, dynamically correcting in real time according to driving environment, and finally realizing safe and comfortable lane changing.
Drawings
FIG. 1 is a system control block diagram of the present invention;
FIG. 2 is a schematic diagram of a model of a trajectory of a vehicle during a lane change;
FIG. 3 is a diagram of relevant parameters during a lane change of a vehicle;
FIG. 4 is a schematic illustration of the translation of the sinusoid along axis X, Y at the beginning of a lane change;
FIG. 5 is a schematic view of a kinematic model of a lane-change vehicle;
FIG. 6 is a logic flow diagram of the method for automatic lane change control for a vehicle based on a sine function in accordance with the present invention;
FIG. 7 is a lane change test chart of the real vehicle of embodiment 1;
FIG. 8 is a lane change test chart of the real vehicle of embodiment 2;
fig. 9 is a lane change test chart of the real vehicle of embodiment 3.
Detailed Description
The invention discloses a vehicle automatic lane changing control method based on a sine function, which comprises the following steps:
s1, building a basic model:
in the actual driving working condition, when the driver changes lane to the left, the steering wheel is controlled to turn left firstly and then return to the right, and in the process, the angle change of the steering wheel and the steering change of the vehicle are consistent in trend and approximate to an S shape.
S11, basic track model: the present patent uses a sine function as a model of the vehicle running track, as shown in fig. 2, which is in accordance with the above "S" shape in form, and has the advantages of continuous curvature, no step phenomenon, low computation overhead, good real-time performance, etc.
y ═ sin (x) x ∈ [ -pi/2, pi/2 ] (formula 1);
the first derivative of the equation 1 is,
Figure BDA0003326275680000051
the formula calculates each slope on the sine curve;
s12, according to the track model after the deformation of the real environment:
in a real environment, the lane-changing running track of the vehicle is influenced by the state of the vehicle, the state of the vehicle ahead, lane lines and the like, so that the basic model is expanded and deformed to cover key parameters as follows:
y ═ Asin (ω x + θ) + B (formula 3)
Wherein, A is the amplitude of the sine function, SLW is defined as the width of the local lane, LLW is the width of the left lane, as shown in FIG. 4, the sine wave is only in (half of the left lane +)Half of the own lane) and, therefore, the amplitude of the sine function
Figure BDA0003326275680000052
Figure BDA0003326275680000053
With the vehicle traveling direction as the longitudinal direction, a represents the distance of the lateral movement of the vehicle between the two lanes in this formula (3). In essence, the lateral variation of the vehicle is laterally moving from the center of the own lane to the center of the left lane.
y is the transverse distance in the lane changing process of the vehicle, and when the lane changing is started, y is 0.
x is the longitudinal distance in the lane changing process of the vehicle, is consistent with the traveling direction, and is 0 when the lane changing is started.
The distance projected by the vehicle track on the X axis is Dmax, and the maximum longitudinal distance required for completing lane change can be calculated by the vehicle speed V of lane change and the time T required for completing lane change: dmax is V x T,
in this embodiment, the formula is required by substituting the longitudinal distance in the X-axis direction, which is the running direction of the vehicle, into the sine function
Figure BDA0003326275680000054
Conversion to an angle, i.e.
Figure BDA0003326275680000055
B is equal to a, the sin curve translates a along the positive axis Y, and when the lane change is started, Y is equal to 0;
theta-pi/2, the sin curve is shifted pi/2 along the positive X axis, ensuring that at the beginning of the lane change, X is 0. The sinusoidal translation along the axis X, Y is schematically illustrated in FIG. 4.
The first derivative of equation (3) is: y ═ a ω cos (ω x + θ) (formula 4)
FIG. 3 shows a diagram of related parameters;
s2. constraint conditions
S21, setting lane changing speed:
vehicle speed condition for automatic lane change of vehicleOne, the user or the host factory sets that the automatic lane change is allowed when the required vehicle speed is greater than a certain critical value, and the critical value is defined as the lane change enabling vehicle speed Venable. For example, when the required vehicle speed is greater than 60KPH, the automatic lane change is allowed, and the lane change enabling vehicle speed V of the vehicleenable is 60 KPH.
Wherein, is Δ Vthr、ΔDthrRespectively two known quantities, Δ V, calibrated at design timethrFor maximum value of speed difference with the preceding vehicle when starting automatic lane change, Δ DthrTo initiate the maximum safe distance to the preceding vehicle during automatic lane change, for example, if the speed difference Δ V between the vehicle and the preceding vehicle is always allowed to fluctuate within the 3KPH range, while from the vehicle and the preceding vehicle speed, a theoretical safe distance D can be derived by a safety strategy mechanism, and if the difference Δ D between the actual vehicle distances Dreal and D is always 2 meters smaller, it is considered that the following vehicle has been stabilized, the aforementioned Δ VthIs 3KPH,. DELTA.DthrIs 2 meters. Current vehicle speed vxGreater than lane change enabling vehicle speed VenableAnd stably following the preceding vehicle, and the speed difference DeltaV from the preceding vehicle<ΔVthrAnd a difference Δ D between the safety distance and the safety distance of the preceding vehicle<Δ DthrFor a period of time t, t is more than or equal to 3s, the system will use the current speed vxAnd starting lane change as a longitudinal vehicle speed, and solving the actual vehicle speed v by a sine function in the lane change process.
S22, maximum longitudinal distance D generated by lane changingmax：
Lane change completion time TendWith the desired longitudinal vehicle speed vxThe product being the maximum longitudinal distance D resulting from a lane changemaxI.e. by
Dmax＝vx×TendIn fact, the sinusoidal function variable x ∈ [0, D ]max]；
Wherein, the lane change completion time TendThe time is 5-8 seconds, and the calibration can be carried out;
s23, maximum slope k of lane change steering trackmax：
As can be seen from formula 4, when ω x is — θ, the slope is maximum, kmax＝Aω。kmaxAnd determining the severity of lane-changing steering behavior. Different speed intervals are providedFixed upper limit value klimitWhen k ismax>klimitAnd forbidding lane change.
S24, the lane line and the left lane line of the vehicle can be seen, the width belongs to (3.75m + delta e), and the curvature radius is larger than a set threshold value Lmax_radius(e.g., 2000m), defined as a threshold of 1500 m; Δ e is the error, which may be defined herein as plus or minus 0.2 m.
And S25, a left lane is provided, and lane changing is allowed when no vehicle exists in front or the distance between a front left vehicle and the vehicle meets the time interval between safety vehicles.
The time-distance algorithm of the workshop is Dw＝Th*Vs-K*(Vf-Vs)+D0，
Wherein D iswThe distance between the vehicles is the current vehicle-to-vehicle distance, namely the distance between the vehicle in front of the vehicle or on the left or in front of the vehicle and the vehicle;
Vsthe vehicle speed is the vehicle speed;
Ththe ACC maintains a corresponding distance according to the time interval, i.e. the time between the host vehicle and the front or left or front left vehicle, i.e. the time required for the host vehicle to reach the current position of the front or left or front left vehicle at the current speed of the host vehicle.
VfThe vehicle speed is equal to the vehicle speed of the front vehicle;
D0the minimum safe distance is a standard quantity, and is usually 3.5 meters; k is the adjustment factor, also normalized, in the project, usually 0.45.
S26, a left lane, no vehicle behind or behind the left lane or the pre-collision time between the left rear vehicle and the vehicle is larger than a preset threshold value RCTTTCAllowing lane change; wherein, RCTTTCIs a standard quantity, typically taken for 2 seconds;
if the above conditions S21-S26 are satisfied, the process proceeds to step S3 to start lane changing;
s3, assuming that the whole working condition is an ideal state without loss, the longitudinal speed v of the vehiclexThe T +1 state and the required control quantity can be derived by combining a sine function according to the time state of T.
At time T, the longitudinal speed is vxt＝vxLongitudinal distance XtWhen T +1 is expected, longitudinalDistance and lateral distance:
Xt+1＝Xt+vxt*ΔT (5)，
Yt+1＝Asin(ω*Xt+1+θ)+B (6)
when T +1 is obtained by substituting equation (6) for equation (4), the slope of the tangent to the sinusoidal curve, i.e., the slope of the tangent to the vehicle-type trajectory:
Figure BDA0003326275680000071
further, the included angle between the tangent and the X axis, i.e. the T +1 moment yaw angle gamma can be deducedt+1：
Figure BDA0003326275680000072
Has been set at a constant longitudinal velocity vxActual vehicle speed vrDecomposed into longitudinal vehicle speed v along the X-axisxAnd a transverse vehicle speed v along the Y axisyPolicy requirement v throughout the lane change processxConstant, then vrVehicle speed (vr) at time T +1 which changes with the change of yaw anglet+1) It should be:
Figure BDA0003326275680000073
further, the speed control amount ACC can be derived as follows:
Figure BDA0003326275680000074
annotate vrtThe vehicle speed at time T.
From the vehicle kinematics model in fig. 5, the following formula can be derived:
Δγ＝γt+1-γtwherein γ istIs the yaw angle of the vehicle at time T,
Figure BDA0003326275680000075
namely, it is
Figure BDA0003326275680000081
Delta is the steering wheel deflection angle and L is the vehicle wheelbase.
According to the steering wheel angular transmission ratio mapping table of table 1, at different speeds, the yaw angle of the vehicle and the angular ratio of the steering wheel are different, and by combining 9, the time T +1, the steering wheel angle, can be obtained: and obtaining the steering control quantity by using the S-map (delta).
TABLE 1 steering wheel care-of ratio map
Vehicle speed KPH 10 20 40 60 80 100 140
Transmission ratio 15.00977 9.299805 5.399902 4.299805 3.5 3.5 3
Since the multi-domain controller transmits the control information on the speed control amount, the steering control amount, and the like in a cycle of 20ms, the unit of Δ T in the system calculation is 0.02.
The automatic lane change Assistant (ALC) implementation strategy related to the patent, as shown in figure 1, measures the information (distance, speed) of the vehicle ahead in real time through a distance sensor (such as a radar) and a vision sensor (such as a camera), the information of the vehicle coming from the side and the rear, the information of the lane and the like, in the embodiment, the information comprises a short-distance radar SRR, a middle-distance radar MRR and an intelligent camera IPM, the information of the side target captured by the radar and the camera is transmitted to a multi-domain controller MDC, then a turning angle instruction is sent to a steering wheel through the multi-domain controller MDC, an electric power steering system EPS is communicated with a vehicle steering control system VSC, meanwhile, the multi-domain controller MDC sends an acceleration/deceleration signal to a vehicle body electronic stability system, an accelerator/brake control vehicle speed quantity is transmitted to an electronic control unit ECU of the vehicle, and then a proper track driving is planned based on the strategy of the patent, and according to the driving environment, the lane change is dynamically corrected in real time, and finally, the lane change is safely and comfortably realized.
In this case, the multi-domain controller (MDC) acquires external information, i.e., lane information (lane width, curvature, lateral position DY of the host vehicle in the lane), front/rear left information (speed, distance), and host vehicle information (vehicle speed), at a cycle of 20 ms.
A multi-domain controller (MDC) sends control information, namely acceleration/deceleration ACC, in a period of 20ms to control the vehicle speed; the steering wheel angle S to control the vehicle steering.
In actual conditions, the system is influenced by driving environment and self state, related control quantity cannot ensure that the vehicle track runs as expected, and the system needs to monitor in real time and carry out compensation and correction in the following mode.
In the present system, lane change is the primary consideration point, so the lateral distance DY between the vehicle and the lane line is used as the reference.
At time T, the current transverse distance Yr can be obtained according to the lane line informationtMeanwhile, the longitudinal distance can be obtained by an arcsine function:
Figure BDA0003326275680000082
from equation (5), the longitudinal distance Xp at time T-1 can be expectedtWith the formula (10), the vertical distance error Δ X ═ Xr can be obtainedt-Xpt)。
When X is presenthth>ΔX＝(Xrt-Xpt)>XlthWhen this occurs, a compensation operation is required. Note: xlthIs a error threshold; xhthIs an effective error threshold value when Δ X>XhthThe errors may be considered untrustworthy.
To compensate for Δ X, it is necessary that T be to T +1, and the expected longitudinal displacement should be
ΔXt+1＝ΔX+vxt*ΔT，
The required longitudinal speed can then be derived:
Figure BDA0003326275680000091
the new speed control amount ACC and the new steering control amount S are obtained by combining the formula (11) with the formula (7), the formula (8), and the formula (9).
Safety collision avoidance:
in the lane changing process, the conditions of the front vehicle and the left front vehicle (if existing) need to be monitored in real time, and the pre-collision time is passed
Figure BDA0003326275680000092
Figure BDA0003326275680000093
As the condition for taking over the driver as the exit of the lane changing process, the threshold value of the collision time can be determined according to different speed zonesThe intervals are set separately.
Example 1 is shown in FIG. 7.
The vehicle speed in front of the lane is 100KPH (27.78m/s), the set cruising vehicle speed of the vehicle is 120KPH (33.33m/s), and the lane width is 3.75 m.
When the vehicle stably follows the front vehicle, the vehicle changes lane at a longitudinal speed of about 100KHP, and the user sets that the lane change needs 6 seconds to be completed, the longitudinal distance of the vehicle in the whole process is 27.78 × 6-166.68 m. After the lane change is completed, the vehicle runs at the set cruising speed. The relevant data are shown in fig. 7, as expected.
Example 2 see figure 8.
The vehicle speed in front of the lane is 50KPH (13.89m/s), the set cruising vehicle speed of the vehicle is 80KPH (22.22m/s), and the lane width is 3.75 m.
When the vehicle stably follows the front vehicle, the vehicle changes lane at a longitudinal speed of about 50KHP, and the user sets that the lane change needs 6 seconds to be completed, the longitudinal distance of the vehicle in the whole process is 13.89 × 6-83.34 m. After the lane change is completed, the vehicle runs at the set cruising speed. The relevant data is as expected, as shown in fig. 8.
Example 3 see figure 9.
The vehicle speed in front of the lane is 50KPH (13.89m/s), the set cruising vehicle speed of the vehicle is 80KPH (22.22m/s), and the lane width is 3.75 m. When the vehicle stably follows the front vehicle, the vehicle changes lane at a longitudinal speed of about 50KHP, and the user sets that the lane change needs to be completed in 8 seconds, the longitudinal distance of the vehicle in the whole process is 13.89 × 8-111.12 m. After the lane change is completed, the vehicle runs at the set cruising speed. The relevant data is as expected, as shown in fig. 8.
The practical measurement of each embodiment can confirm that the Automatic Lane Change (ALC) control method related to the patent meets the design expectation and can meet the use requirement.
It should be understood that the above embodiments are only for illustrating the technical solutions of the present invention and not for limiting the same, and although the present invention is described in detail with reference to the above embodiments, those skilled in the art should understand that the modifications or equivalent substitutions can be made on the specific embodiments of the present invention without departing from the spirit and scope of the present invention, and all modifications or equivalent substitutions should be covered in the claims of the present invention.

Claims (2)

1. A vehicle automatic lane change control method based on a sine function is characterized by comprising the following steps:
s1, building a basic model:
in the actual driving working condition, when a driver changes lane to the left, the steering wheel is controlled to turn left firstly and then return to the right, and in the process, the angle change of the steering wheel is consistent with the steering change of the vehicle in a trend way and is approximate to an S shape;
s11, basic track model: taking a sine function as a vehicle running track model,
y ═ sin (x) x ∈ [ -pi/2, pi/2 ] (formula 1);
the first derivative of the equation 1 is,
Figure FDA0003326275670000011
the formula calculates each slope on the sine curve;
s12, according to the track model after the deformation of the real environment:
the base model is subjected to extended deformation to cover the key parameters as follows:
y ═ Asin (ω x + θ) + B (formula 3)
Wherein A is the amplitude of the sine function, SLW is defined as the width of the lane, LLW is the width of the left lane, and the amplitude of the sine function
Figure FDA0003326275670000012
Taking the vehicle running direction as a longitudinal direction;
y is the transverse distance in the lane changing process of the vehicle, and when lane changing is started, y is 0;
x is the longitudinal distance in the lane changing process of the vehicle and is consistent with the advancing direction, and when lane changing is started, x is 0;
the distance of the vehicle track projection on the X axis is Dmax, and the Dmax is V X T which is the maximum longitudinal distance required for completing lane changing;
omega is a rotationThe conversion coefficient is that the longitudinal distance of the vehicle in the X-axis direction is taken as a parameter (X), and is substituted into a sine function, and a formula is required
Figure FDA0003326275670000013
Conversion to an angle, i.e.
Figure FDA0003326275670000014
B is equal to a, the sin curve translates a along the positive axis Y, and when the lane change is started, Y is equal to 0;
theta is-pi/2, the sin curve is shifted pi/2 along the positive X axis, and X is 0 when the lane change is started;
the first derivative of equation (3) is: y ═ a ω cos (ω x + θ) (formula 4)
S2. constraint conditions
S21, setting lane changing speed:
current vehicle speed vxGreater than lane change enabling vehicle speed VenableAnd stably following the preceding vehicle, and the speed difference DeltaV from the preceding vehicle<ΔVthrAnd a difference Δ D between the safety distance and the safety distance of the preceding vehicle<ΔDthrFor a period of time t, t is more than or equal to 3s, the system will use the current speed vxStarting lane changing as a longitudinal vehicle speed, and solving an actual vehicle speed v by a sine function in the lane changing process; wherein, is Δ VthrFor maximum value of speed difference with the preceding vehicle when starting automatic lane change, Δ DthrThe maximum value of the safety distance between the front vehicle and the front vehicle when the automatic lane change is started;
s22, maximum longitudinal distance D generated by lane changingmax：
Lane change completion time TendWith the desired longitudinal vehicle speed vxThe product being the maximum longitudinal distance D resulting from a lane changemaxI.e. Dmax＝vx×TendThe sine function variable x is the [0, D ]max]；
Wherein, the lane change completion time Tend5-8 seconds as standard quantity;
s23, maximum slope k of lane change steering trackmax：
kmaxThe upper limit value k is set for different speed intervalslimitWhen k ismax>klimitForbidding lane change;
s24, the lane line and the left lane line of the vehicle can be seen, the width belongs to (3.75m + delta e), and the curvature radius is larger than a set threshold value Lmax_radius；
S25, a left lane is provided, and lane changing is allowed when no vehicle exists in front or the distance between a front left vehicle and the vehicle meets the time interval of a safe workshop;
the time-distance algorithm of the workshop is Dw＝Th*Vs-K*(Vf-Vs)+D0，
Wherein D iswThe distance between the vehicles is the current vehicle-to-vehicle distance, namely the distance between the vehicle in front of the vehicle or on the left or in front of the vehicle and the vehicle;
Vsthe vehicle speed is the vehicle speed;
Ththe time interval between vehicles is the time between the vehicle and the vehicle in front or on the left or in front of the left, namely the time required for reaching the current position of the vehicle in front or on the left or in front of the left at the current speed of the vehicle;
Vfthe vehicle speed is equal to the vehicle speed of the front vehicle;
D0the minimum safe distance is a standard quantity; k is an adjustment coefficient and is a standard quantity;
s26, a left lane, no vehicle behind or behind the left lane or the pre-collision time between the left rear vehicle and the vehicle is larger than a preset threshold value RCTTTCAllowing lane change; RCT (Radar Cross section)TTCIs a standard quantity;
if the above conditions S21-S26 are satisfied, the process proceeds to step S3 to start lane changing;
s3, assuming that the whole working condition is an ideal state without loss, and the longitudinal speed v of the vehiclexThe constant state can be obtained, namely the T +1 state and the required control quantity can be deduced according to the time state of T by combining a sine function;
at time T, the longitudinal speed is vxt＝vxLongitudinal distance XtWhen T +1 is expected, the longitudinal distance and the lateral distance:
Xt+1＝Xt+vxt*ΔT (5)，
Yt+1＝Asin(ω*Xt+1+θ)+B (6)
when equation (6) is substituted for equation (4) to obtain T +1, the tangent slope of the sinusoidal curve, i.e., the tangent slope of the vehicle-form trajectory:
Figure FDA0003326275670000021
further, the included angle between the tangent and the X axis, i.e. the T +1 moment yaw angle gamma can be deducedt+1：
Figure FDA0003326275670000022
Has been set at a constant longitudinal velocity vxActual vehicle speed vrDecomposed into longitudinal vehicle speed v along the X-axisxAnd a transverse vehicle speed v along the Y axisyPolicy requirement v throughout the lane change processxConstant, then vrVehicle speed (vr) at time T +1 which changes with the change of yaw anglet+1) Comprises the following steps:
Figure FDA0003326275670000031
further, the speed control amount ACC can be derived as follows:
Figure FDA0003326275670000032
vrtthe vehicle speed at time T;
Δγ＝γt+1-γtwherein γ istIs the yaw angle of the vehicle at time T,
Figure FDA0003326275670000033
namely, it is
Figure FDA0003326275670000034
Delta is a deflection angle of a steering wheel, and L is a vehicle wheelbase;
time T +1, steering wheel angle: and obtaining the steering control quantity by using the S-map (delta).
2. The sinusoidal function-based automatic lane change control method of a vehicle according to claim 1, further comprising the following compensation correction steps:
at time T, the current transverse distance Yr is obtained according to the lane line informationtWhile the longitudinal distance is derived from the arcsine function:
Figure FDA0003326275670000035
from equation (5), the longitudinal distance Xp at time T-1 can be expectedtCombining equation (10) to obtain the longitudinal distance error Δ X ═ Xrt-Xpt)；
When X is presenthth>ΔX＝(Xrt-Xpt)>XlthWhen the operation is needed, compensation operation is needed;
Xlthis a error threshold; xhthEffective error threshold when Δ X>XhthThe error can be considered as unreliable;
to compensate for Δ X, it is necessary that T be to T +1, and the expected longitudinal displacement should be Δ Xt+1＝ΔX+vxtΔ T, the required longitudinal velocity is derived:
Figure FDA0003326275670000036
the new speed control amount ACC and the new steering control amount S are obtained by combining the formula (11) with the formula (7), the formula (8), and the formula (9).
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