CN114820771A - Method and system for controlling electric tractor and trailer to realize large-angle butt joint - Google Patents

Method and system for controlling electric tractor and trailer to realize large-angle butt joint Download PDF

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CN114820771A
CN114820771A CN202210533626.3A CN202210533626A CN114820771A CN 114820771 A CN114820771 A CN 114820771A CN 202210533626 A CN202210533626 A CN 202210533626A CN 114820771 A CN114820771 A CN 114820771A
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tractor
trailer
arc
butt joint
angle
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李卫华
李国庆
王艳桃
靳磊
习辉
王剑锋
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State Grid Smart Energy Traffic Technology Innovation Center Suzhou Co ltd
Harbin Institute of Technology Weihai
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State Grid Smart Energy Traffic Technology Innovation Center Suzhou Co ltd
Harbin Institute of Technology Weihai
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Abstract

A method and a system for controlling an electric tractor and a trailer to realize large-angle butt joint relate to the technical field of automatic butt joint of tractors and trailers and are used for solving the problems of high hardware cost or low butt joint accuracy required by the existing automatic butt joint method of the tractor and the trailer. The technical points of the invention comprise: the relative positions of the tractor and the trailer are judged by utilizing the current pose states of the tractor and the trailer, an ackermann corner at the current moment is calculated, a tractor wire-control steering mechanism instruction is generated, a front wheel corner is changed, the longitudinal axis of the tractor gradually approaches the longitudinal axis of the trailer until the longitudinal axes of the tractor and the trailer are superposed, and therefore automatic butt joint of the tractor and the trailer is controlled based on the ackermann corner under a large-angle condition. The invention is suitable for the automatic butt joint of the electric tractor and the trailer under the condition of large angle.

Description

Method and system for controlling electric tractor and trailer to realize large-angle butt joint
Technical Field
The invention relates to the technical field of automatic butt joint of a tractor and a trailer, in particular to a method and a system for controlling an electric tractor and the trailer to realize large-angle butt joint.
Background
With the rapid development of vehicle intellectualization and interconnection sharing, many driving assistance systems and unmanned technology development and application have appeared in recent years. For example, the automatic navigation driving-assistant system senses the environment around the vehicle through a camera, a laser radar, a millimeter wave radar and a high-precision GPS on the vehicle so as to control the vehicle to automatically run, and the automatic navigation driving-assistant system comprises functions of automatic overtaking, optimal lane selection, automatic highway switching, automatic on-off ramp and the like, so that the fatigue of a driver can be greatly reduced in long-distance driving. However, the existing assistant driving system and unmanned driving technology are mostly applied to passenger cars, and the traditional manual driving mode is still adopted for the car types such as trucks, vans, tractors and the like. On some wharves, a driver needs to drive a tractor to complete tasks of butt joint with a trailer, unhooking, goods transportation and the like, so that the driver is required to have high operation technology and high working strength, and the investment and the cost are high in the life and production.
With the development of times trend, in the future dock production, the traditional manual driving tractor is gradually replaced by adopting a vehicle intelligentization and unmanned mode, the functions of automatically connecting the tractor with a trailer and the like are realized, and the ideal production mode of intelligent production and transportation and an unmanned dock is gradually realized. The process that the tractor automatically backs a car under the condition of large angle and is in butt joint with the trailer is a process of backing a car at low speed and large angle, and the speed of the tractor is very low, generally below 1.5 km/h. The path trajectory planning when the vehicle is automatically reversed can be divided into: the method comprises a discontinuous curvature path planning method, a grid discrete type track planning method, a fuzzy control and BP neural network dynamic track planning method and a B-spline curve continuous curvature path planning method.
The method for planning the path with discontinuous curvature has obvious defects that the continuity of the whole reversing process is poor; the back-up track planning and track calculation of the grid discrete type track planning method are simple, but the dot matrix is not always on the optimal back-up path, so that the back-up space is large and a proper feasible curve can not be found; the fuzzy control and BP neural network dynamic trajectory planning method can dynamically adjust the backing motion in real time, the whole process is smooth, but the dynamic process is excessive to initiate the state and learn samples, the control program is complex, the requirement on the response speed of a controller is high, and the cost of software and hardware is increased; a path planning method for continuous curvature of a B-spline curve is characterized in that when the initial state is different, even if the control point positions are the same, the obtained curves are still different, the B-spline curve is difficult to be changed into a vehicle control sequence which can be actually operated, and the B-spline curve is not matched with the track where a vehicle runs.
Disclosure of Invention
The invention provides a method and a system for controlling an electric tractor and a trailer to realize large-angle butt joint, which aim to solve the problems that the existing method for manually driving the tractor to back a car and connecting the trailer needs high operation technical requirements of a driver and the existing automatic butt joint method needs high hardware cost or low butt joint accuracy.
According to one aspect of the invention, a method for controlling an electric tractor and a trailer to realize large-angle butt joint is provided, the method enables the tractor to back up according to different automatic butt joint modes respectively according to different scenes where the tractor and the trailer are located, so that longitudinal axes of the tractor and the trailer are coincided before butt joint, and the specific process comprises the following steps:
judging whether the longitudinal axes of the tractor and the trailer are parallel or not according to the relative pose information of the tractor and the trailer, and enabling the tractor to be in a reversing state; if the longitudinal axes of the tractor and the trailer are parallel, judging whether the transverse deviation of the tractor and the trailer is within the range of a preset threshold value, if so, determining that the tractor and the trailer are in a linear reversing scene, and entering a linear reversing automatic butt joint mode; if the distance is not within the range of the preset threshold value, the tractor and the trailer are determined to be in a parallel reversing scene, and the automatic parallel reversing butt joint mode is entered; and if the longitudinal axes of the tractor and the trailer are not parallel, determining that the tractor and the trailer are in a herringbone reversing scene, and entering a herringbone reversing automatic butt joint mode.
Further, the preset threshold is 0.15 meter.
Further, the parallel reverse automatic docking mode is as follows: adopting a two-section arc reversing method according to the Ackerman corner corresponding to the first section arc
Figure BDA0003646996560000021
Ackerman corner corresponding to second segment of arc
Figure BDA0003646996560000022
Generating a tractor steer-by-wire command to cause longitudinal axes of the tractor and the trailer to coincide; ackerman corner
Figure BDA0003646996560000023
And
Figure BDA0003646996560000024
the calculation process specifically includes:
let the radius corresponding to the first arc be R 1 The corresponding radius of the second section of circular arc is R 2 The circle centers of the first section of arc and the second section of arc are respectively arranged at two sides of the middle point of the transverse distance between the tractor and the trailer; then, according to the corresponding position relation, calculating to obtain:
Figure BDA0003646996560000025
in the formula, L 0 Representing the two-section type circular arc backing from the initial backing position of the rear shaft of the tractor to the completion of backingThe longitudinal distance covered, Δ x, represents the lateral deviation of the tractor from the trailer;
so that R 1 ＝R 2 Calculated from the above equation:
Figure BDA0003646996560000026
the ackermann angle corresponding to the first arc
Figure BDA0003646996560000027
Ackerman corner corresponding to second segment of arc
Figure BDA0003646996560000028
Respectively as follows:
Figure BDA0003646996560000029
Figure BDA0003646996560000031
in the formula, L represents a truck wheel base.
Further, the herringbone reverse automatic docking mode is as follows: when the herringbone reverse vehicle is arranged, the corresponding ackermann corner is
Figure BDA0003646996560000032
According to calculated Ackerman angle
Figure BDA0003646996560000033
Generating a tractor steer-by-wire command to cause longitudinal axes of the tractor and the trailer to coincide; ackerman corner
Figure BDA0003646996560000034
The formula is as follows:
Figure BDA0003646996560000035
wherein L represents a tractor wheelbase; r represents the radius corresponding to the arc segment of the tractor backing, and the calculation process is as follows:
setting the intersection point of the longitudinal axes of the tractor and the trailer as N, and connecting the central point M of the rear shaft of the tractor and the intersection point N to form a line segment MN; the corresponding origin of the arc section of the tractor for backing is O 1 And then:
R＝MN·tan∠O 1 NM
in the formula (I), the compound is shown in the specification,
Figure BDA0003646996560000036
theta is the angle between the tractor and the longitudinal axis of the trailer.
Further, the automatic docking mode of the linear reverse is as follows: and finely adjusting the front wheel corner of the tractor according to the transverse deviation of the tractor and the trailer and the included angle of the longitudinal axes of the two vehicles, so that the longitudinal axes of the tractor and the trailer are overlapped.
Further, after the automatic docking mode reversing is completed, namely the longitudinal axes of the tractor and the trailer are overlapped, the automatic docking mode is disengaged, and the automatic reversing of the tractor and the docking of the tractor and the trailer are completed.
According to another aspect of the invention, a system for controlling an electric tractor and a trailer to realize large-angle butt joint is provided, wherein the system enables the tractor to back up according to different automatic butt joint modes respectively according to different scenes where the tractor and the trailer are located, so that the longitudinal axes of the tractor and the trailer are overlapped before butt joint; the method comprises the following steps:
a relative pose acquisition module configured to acquire relative pose information of the tractor and the trailer;
the linear reversing module is configured to determine that the tractor and the trailer are in a linear reversing scene and enter a linear reversing automatic docking mode when the fact that the longitudinal axes of the tractor and the trailer are parallel and the transverse deviation of the tractor and the trailer is within the range of a preset threshold value is determined according to the relative pose information of the tractor and the trailer;
the parallel backing module is configured to determine that the tractor and the trailer are in a parallel backing scene and enter a parallel backing automatic docking mode when the fact that the longitudinal axes of the tractor and the trailer are parallel and the lateral deviation of the tractor and the trailer is not within the range of a preset threshold value is determined according to the relative pose information of the tractor and the trailer;
and the herringbone backing module is configured to determine that the tractor and the trailer are in a herringbone backing scene and enter a herringbone backing automatic butt joint mode when the fact that the longitudinal axes of the tractor and the trailer are not parallel is determined according to the relative pose information of the tractor and the trailer.
Further, the preset threshold is 0.15 meter.
Further, in the parallel reversing module, the parallel reversing automatic docking mode is as follows: adopting a two-section arc reversing method according to the Ackerman corner corresponding to the first section arc
Figure BDA0003646996560000041
Ackerman corner corresponding to second segment of arc
Figure BDA0003646996560000042
Generating a tractor steer-by-wire command to cause longitudinal axes of the tractor and the trailer to coincide; ackerman corner
Figure BDA0003646996560000043
And
Figure BDA0003646996560000044
the calculation process specifically includes:
let the radius corresponding to the first arc be R 1 The corresponding radius of the second section of circular arc is R 2 The circle centers of the first section of arc and the second section of arc are respectively arranged at two sides of the middle point of the transverse distance between the tractor and the trailer; then, according to the corresponding position relation, calculating to obtain:
Figure BDA0003646996560000045
in the formula, L 0 The longitudinal distance from the initial backing position of the rear shaft of the tractor to the completion of two-section arc backing is represented, and the delta x represents the transverse deviation between the tractor and the trailer;
so that R 1 ＝R 2 Calculated from the above equation:
Figure BDA0003646996560000046
the ackermann angle corresponding to the first arc
Figure BDA0003646996560000047
Ackerman corner corresponding to second segment of arc
Figure BDA0003646996560000048
Respectively as follows:
Figure BDA0003646996560000049
Figure BDA00036469965600000410
in the formula, L represents a truck wheel base.
Further, the herringbone reverse module comprises the following herringbone reverse automatic butt joint modes: when the herringbone reverse vehicle is arranged, the corresponding ackermann corner is
Figure BDA00036469965600000411
According to calculated Ackerman angle
Figure BDA00036469965600000412
Generating a tractor steer-by-wire command to cause longitudinal axes of the tractor and the trailer to coincide; ackerman corner
Figure BDA00036469965600000413
The formula is as follows:
Figure BDA00036469965600000414
wherein L represents a tractor wheelbase; r represents the radius corresponding to the arc segment of the tractor backing, and the calculation process is as follows:
setting the intersection point of the longitudinal axes of the tractor and the trailer as N, and connecting the central point M of the rear shaft of the tractor and the intersection point N to form a line segment MN; the corresponding origin of the arc section of the tractor for backing is O 1 And then:
R＝MN·tan∠O 1 NM
in the formula (I), the compound is shown in the specification,
Figure BDA0003646996560000051
theta is the angle between the tractor and the longitudinal axis of the trailer.
The beneficial technical effects of the invention are as follows:
according to the invention, an ackermann corner is calculated according to the transverse deviation and the azimuth angle of the tractor and the trailer, a tractor steer-by-wire command is generated, and the system controller is driven to change the steering of the tractor, so that the transverse error and the azimuth angle of the tractor and the trailer are reduced, and the posture of the tractor in the process of backing a car is continuously adjusted until the butt joint with the trailer is completed. The invention can solve the problems that the existing driver needs high driver operation technology and high working strength when driving the tractor, and the investment is large and the cost is high in the life production in the unmanned automatic butt joint of the tractor. In the future production and life of wharfs, the invention provides an automatic docking method of the unmanned tractor for unmanned wharfs and intelligent wharfs, and the feasibility and effectiveness of the invention are verified by using the results of real vehicle tests.
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The present invention may be better understood by reference to the following description taken in conjunction with the accompanying drawings, which are incorporated in and form a part of this specification, and which are used to further illustrate preferred embodiments of the present invention and explain the principles and advantages of the present invention.
Fig. 1 is a schematic flow chart of a method for controlling an electric tractor and a trailer to realize large-angle docking according to an embodiment of the present invention;
fig. 2 is another flowchart of a method for controlling an electric tractor and a trailer to realize large-angle docking according to an embodiment of the present invention;
FIG. 3 is a schematic diagram of a tractor automatically backing up and docking with a trailer in a parallel backing up scene according to an embodiment of the invention;
fig. 4 is a schematic diagram of the automatic reverse of the tractor and the butt joint of the tractor in the herringbone reverse scene in the embodiment of the invention.
Detailed Description
In order that those skilled in the art will better understand the disclosure, exemplary embodiments or examples of the disclosure are described below with reference to the accompanying drawings. It is obvious that the described embodiments or examples are only some, but not all embodiments or examples of the invention. All other embodiments or examples, which can be obtained by a person skilled in the art without making any creative effort based on the embodiments or examples in the present invention, shall fall within the protection scope of the present invention.
The embodiment of the invention provides a method for controlling an electric tractor and a trailer to realize large-angle butt joint, which enables the tractor to back up according to different automatic butt joint modes respectively according to different scenes where the tractor and the trailer are positioned so as to enable the longitudinal axes of the tractor and the trailer to coincide before butt joint, and the specific process comprises the following steps:
judging whether longitudinal axes of the tractor and the trailer (namely, central axes passing through a longitudinal vehicle body) are parallel or not according to the relative pose information of the tractor and the trailer, and enabling the tractor to be in a reversing state; if the longitudinal axes of the tractor and the trailer are parallel, judging whether the transverse deviation of the tractor and the trailer is within the range of a preset threshold value, if so, determining that the tractor and the trailer are in a linear reversing scene, and entering a linear reversing automatic butt joint mode; if the distance is not within the range of the preset threshold value, the tractor and the trailer are determined to be in a parallel reversing scene, and the automatic parallel reversing butt joint mode is entered; and if the longitudinal axes of the tractor and the trailer are not parallel, determining that the tractor and the trailer are in a herringbone reversing scene, and entering a herringbone reversing automatic butt joint mode.
In this embodiment, optionally, the preset threshold is 0.15 meter.
In this exampleOptionally, the parallel reverse automatic docking mode is: adopting a two-section arc reversing method according to the Ackerman corner corresponding to the first section arc
Figure BDA0003646996560000061
Ackerman corner corresponding to second segment of arc
Figure BDA0003646996560000062
Generating a tractor steer-by-wire command to cause longitudinal axes of the tractor and the trailer to coincide; ackerman corner
Figure BDA0003646996560000063
And
Figure BDA00036469965600000614
the calculation process specifically includes:
let the radius corresponding to the first arc be R 1 The corresponding radius of the second section of circular arc is R 2 The circle centers of the first section of arc and the second section of arc are respectively arranged at two sides of the middle point of the transverse distance between the tractor and the trailer; then, according to the corresponding position relation, calculating to obtain:
Figure BDA0003646996560000064
in the formula, L 0 The longitudinal distance from the initial backing position of the rear shaft of the tractor to the completion of two-section arc backing is represented, and the delta x represents the transverse deviation between the tractor and the trailer;
so that R 1 ＝R 2 Calculated from the above equation:
Figure BDA0003646996560000065
the ackermann angle corresponding to the first arc
Figure BDA0003646996560000066
Ackerman angle corresponding to second segment of arc
Figure BDA0003646996560000067
Respectively as follows:
Figure BDA0003646996560000068
Figure BDA0003646996560000069
in the formula, L represents a truck wheel base.
In this embodiment, optionally, the herringbone reverse automatic docking mode is as follows: when the herringbone reverse vehicle is arranged, the corresponding ackermann corner is
Figure BDA00036469965600000610
According to calculated Ackerman angle
Figure BDA00036469965600000611
Generating a tractor steer-by-wire command to cause longitudinal axes of the tractor and the trailer to coincide; ackerman corner
Figure BDA00036469965600000612
The formula is as follows:
Figure BDA00036469965600000613
wherein L represents a tractor wheelbase; r represents the radius corresponding to the arc segment of the tractor backing, and the calculation process is as follows:
setting the intersection point of the longitudinal axes of the tractor and the trailer as N, and connecting the central point M of the rear shaft of the tractor and the intersection point N to form a line segment MN; the corresponding origin of the arc section of the tractor for backing is O 1 And then:
R＝MN·tan∠O 1 NM
in the formula (I), the compound is shown in the specification,
Figure BDA0003646996560000071
theta being azimuth, i.e. longitudinal to the tractor and trailerThe angle of the axis.
In this embodiment, optionally, the automatic docking mode of the linear reverse drive is as follows: and finely adjusting the front wheel corner of the tractor according to the transverse deviation of the tractor and the trailer and the included angle of the longitudinal axes of the two vehicles, so that the longitudinal axes of the tractor and the trailer are overlapped.
In this embodiment, optionally, after the automatic docking mode reversing is completed, that is, the longitudinal axes of the tractor and the trailer are already overlapped, the automatic docking mode is disengaged, and the automatic reversing of the tractor and the docking with the trailer are completed.
Another embodiment of the present invention provides a method for controlling an electric tractor and a trailer to realize large-angle docking, as shown in fig. 1 and 2, the method specifically includes the following steps:
the method comprises the following steps: reading the current tractor state, and determining whether the current tractor is in a neutral gear state;
according to the embodiment of the invention, the specific process is as follows: reading the state information of the current vehicle, and confirming that the current tractor is in an N-gear (namely neutral) state through the current vehicle state information transmitted by can communication in an unmanned driving mode; if the tractor is not in a neutral (N-gear) state, a neutral command is sent to drive a system controller, so that the tractor is switched to a neutral (N-gear) mode; if the tractor is already in the neutral state, the next step is executed.
Step two: reading relative pose information transmitted by sensing equipment such as a radar and a camera which are arranged on the tractor and the trailer at present, and judging the scene of the tractor and the trailer at present;
according to the embodiment of the invention, the specific process is as follows: in an initial state, if the axes of the tractor and the trailer are parallel, namely the azimuth angle theta is 0, and if the transverse error between the tractor and the trailer is more than or equal to minus 0.15m and less than or equal to delta x and less than or equal to 0.15m, the tractor and the trailer can be approximately considered to be in a linear backing scene; in an initial state, if the axes of the tractor and the trailer are parallel, namely the azimuth angle theta is 0 at the moment, but the transverse error delta x of the tractor and the trailer is less than or equal to-0.15 m or less than or equal to 0.15m, and then an automatic reverse-connection scene of the tractor and the trailer is entered; in an initial state, if the axes of the tractor and the trailer are not in a parallel state, namely the azimuth angle theta is not equal to 0, then entering a herringbone reverse automatic docking scene of the tractor and the trailer.
Step three: controlling the tractor to automatically reverse, and sending a reverse instruction to the tractor through can communication to enable the tractor to enter a reverse gear mode;
according to the embodiment of the invention, the specific process is as follows: according to the current tractor state information, the tractor is confirmed to be in a neutral gear (N gear) state currently; after the tractor is confirmed to be in a neutral gear (N gear) state at present, a reversing instruction is issued to the tractor through can communication, the tractor is switched to a reverse gear (R gear) state from the current neutral gear (N gear) state, the tractor executes the reversing instruction, and a reversing mode is entered.
Step four: the automatic reversing of the tractor under the condition of a large angle is completed, the ackermann corners of the left wheel and the right wheel of the front wheel are calculated according to the relative positions of the tractor and the trailer, a tractor wire control steering mechanism instruction is generated, the front wheel corner is controlled, and the relative positions of the tractor and the trailer at the next moment are changed until the tractor reverses to a target point;
according to the embodiment of the invention, the specific process is as follows: step 4.1, reading initial pose information of the tractor and the trailer, judging the scene of the current tractor and the trailer, if the tractor and the trailer are in a linear reversing scene at the moment, directly giving a reverse gear (R gear) instruction to the tractor to enable the tractor to enter a reversing mode, and calculating a front wheel corner for enabling the tractor to turn left at the next moment according to a control algorithm and enabling a front wheel of the tractor to execute small-amplitude left-turning action according to transverse errors and azimuth angle information of the tractor and the trailer at the tail reversing stage of the tractor; if the tractor slightly deviates to the left relative to the trailer, calculating a front wheel corner for enabling the tractor to turn right at the next moment according to a control algorithm, and enabling the front wheel of the tractor to execute small-amplitude right-turning action; completing dynamic fine adjustment of the front wheel corner until the longitudinal axis of the tractor and the longitudinal axis of the trailer coincide, and ensuring that the tractor backs linearly in a posture right opposite to the trailer in the following step 5.3 until the tractor is successfully connected with the trailer;
step 4.2, if the tractor and the trailer are in a parallel reverse scene at this time, that is, the azimuth angle θ is 0 at this time, but the lateral error Δ x of the tractor and the trailer is less than or equal to-0.15 m or less than or equal to Δ x of 0.15m at this time, the concrete process of the tractor in the mode of parallel reverse and trailer docking is as follows:
in the parallel reverse automatic docking mode, a two-segment arc method is adopted for backing, as shown in fig. 3, a coordinate system is established with a docking point O of the trailer as an origin, that is, the coordinate of the point O is (0, 0); the origin corresponding to the first section of circular arc is O 1 In the coordinate system of the trailer butt joint O 1 Has the coordinates of (x) O1 ,y O1 ) (ii) a The origin corresponding to the second section of arc is O 2 In the coordinate system of trailer butt joint point 2 Has the coordinates of (x) O2 ,y O2 ) (ii) a The coordinate of the center M of the rear axle of the tractor in the initial position is (x) M ,y M ) The coordinate of the rear axle center M' of the tractor after the completion of the arc backing at the two ends is (x) M′ ,y M′ ) Then, the following formula can be established according to the corresponding position relationship:
(R 1 +R 2 )·sinα-L 0 ＝0 (1)
(R 1 +R 2 )·(1-cosα)＝△x (2)
in the formula: r 1 Radius corresponding to the first arc, R 2 Is the radius corresponding to the second section of arc, and alpha is the origin O of the arcs at both ends 1 O 2 An included angle L with the extension line of the rear shaft after the backing of the second section of circular arc 0 The longitudinal distance from the rear shaft at the initial position of the tractor to the rear shaft after the reverse operation of the second section of circular arc is finished, and delta x is the transverse deviation between the tractor and the trailer.
The following can be obtained from the formulae (1) and (2):
Figure BDA0003646996560000081
Figure BDA0003646996560000082
then from the calculated sin α and cos α, the following formula can be obtained:
Figure BDA0003646996560000091
Figure BDA0003646996560000092
then R can be calculated according to the above formulas (5) and (6) 1 And R 2 After adjusting R 1 And R 2 The optimal path control planning effect is achieved. According to the real vehicle test, selecting R in the invention 1 And R 2 Are 0.5 and 0.5, respectively, then:
Figure BDA0003646996560000093
the calculated ackermann angle size at this time is:
Figure BDA0003646996560000094
Figure BDA0003646996560000095
according to the calculated Ackerman angle of the first segment
Figure BDA0003646996560000096
And a second Ackerman corner
Figure BDA0003646996560000097
Generating tractor steer-by-wire instruction, transmitting for the front wheel corner, changing the steering of tractor, making the axis of tractor continuously approach the trailer axis until its azimuth theta become 0, tractor axis and trailer axis coincidence this momentAnd the automatic reversing action of the tractor under the parallel reversing scene is finished.
4.3, if the tractor and the trailer are in a herringbone reversing scene at the moment, namely the axes of the tractor and the trailer are not in a parallel state at the moment, and the azimuth angle theta of the tractor and the trailer is not equal to 0 at the moment, the concrete process of the tractor in the herringbone reversing and trailer reversing mode is as follows:
when the tractor backs a car at low speed and automatic butt joint of trailer, ackermann corner formula is:
Figure BDA0003646996560000098
wherein L is the wheelbase of the tractor.
As shown in fig. 4, a coordinate system is established with the trailer docking point as an origin O, that is, the coordinate of the point O is (0, 0); the coordinate of the center M of the rear axle of the tractor in a coordinate system established by the butt joint points of the trailers is (x) M ,y M ) Original point O corresponding to circular arc section of automatic backing of tractor 1 The coordinate is (x) O1 ,y O1 ) Then, the coordinate of the intersection point N of the extension line of the trailer axis and the extension line of the tractor axis is obtained as (x) N ,y N ). According to the relative position relationship between the tractor and the trailer, the following can be obtained:
x N ＝0 (11)
y N ＝y M -x M ·tanθ (12)
in the formula: theta is the azimuth angle. The coordinates of the N point at this time are (0, y) M -x M Tan θ). The intersection point N of the tractor rear axle center M connected with the initial pose, the tractor axis extension line and the trailer extension line is MN, and the intersection point N of the tractor axis extension line and the trailer extension line connected with N is the original point O corresponding to the automatic reversing arc section of the tractor 1 Is O 1 N, then O 1 The included angle between N and MN is:
Figure BDA0003646996560000101
the distance MN from the point M to the point N is as follows:
Figure BDA0003646996560000102
according to the angle O 1 The radius R of the arc of the tractor when the vehicle is reversed in a herringbone mode is obtained by NM and the distance MN and is as follows:
R＝MN·tan∠O 1 NM (15)
the ackermann angle at this stage is calculated from the found arc radius R:
Figure BDA0003646996560000103
namely the corresponding ackermann angle is
Figure BDA0003646996560000104
According to calculated Ackerman angle
Figure BDA0003646996560000105
The generation tractor steer-by-wire instruction transmits for the front wheel corner, changes the turning of tractor, makes the axis of tractor constantly approach the trailer axis until its azimuth theta become 0, and tractor axis and trailer axis coincidence this moment accomplish the action that the tractor backed a car automatically under the chevron shape scene.
Step five: reading the relative pose of the tractor and the trailer at the moment, calculating an Ackerman corner at the next moment according to the azimuth angles of the tractor and the trailer, controlling the steering of the tractor at the next moment, and carrying out dynamic fine adjustment until the automatic butt joint of the tractor and the trailer is completed;
according to the embodiment of the invention, the specific process is as follows: step 5.1, calculating the transverse deviation and the azimuth deviation of the current tractor and the trailer, and judging whether the tractor and the trailer are successfully butted; step 5.2, if the tractor and the trailer are successfully butted at the moment, the automatic butting mode is disengaged, and the tasks of automatically backing the tractor and butting the tractor and the trailer are completed;
and 5.3, if the tractor and the trailer are not successfully butted, calculating the currently required ackermann corner according to the transverse deviation and the azimuth deviation information of the tractor and the trailer at the last moment, generating a tractor steer-by-wire instruction, and changing the driving direction of the tractor. And then reading the transverse deviation and the azimuth deviation of the tractor and the trailer at the next moment, calculating the Ackerman corner at the moment, and generating a tractor steer-by-wire command at the next moment. And finally, eliminating the transverse deviation and the azimuth deviation of the tractor and the trailer until the transverse deviation and the azimuth deviation of the tractor and the trailer are gradually reduced. Therefore, the dynamic adjustment of the final docking stage under the condition of automatic reversing of the large-angle tractor is realized, and the tractor is ensured to perform linear reversing in a posture right opposite to the trailer before the trailer is to be docked;
step 5.4, generating a vehicle speed control instruction, driving a system controller, issuing the vehicle speed control instruction to the tractor through can communication, controlling the vehicle speed of the automatic reverse docking process of the tractor, keeping the tractor to perform reverse driving at a low speed, and ensuring that the tractor can be successfully docked with the trailer;
step 5.5, after the step 5.4 is executed, calculating the transverse deviation and the azimuth deviation of the tractor and the trailer again, judging whether the tractor and the trailer are successfully butted at the moment, and if so, executing the step 5.2; and if the docking is not successful, executing the step 5.3 and the step 5.4 until the tractor and the trailer are successfully docked, and quitting the automatic docking mode of the tractor and the trailer to achieve the expected control effect.
Another embodiment of the invention provides a system for controlling an electric tractor and a trailer to realize large-angle butt joint, wherein the system enables the tractor to back up according to different automatic butt joint modes respectively according to different scenes where the tractor and the trailer are located, so that the longitudinal axes of the tractor and the trailer are overlapped before butt joint; the method comprises the following steps:
a relative pose acquisition module configured to acquire relative pose information of the tractor and the trailer;
the linear reversing module is configured to determine that the tractor and the trailer are in a linear reversing scene and enter a linear reversing automatic docking mode when the fact that the longitudinal axes of the tractor and the trailer are parallel and the transverse deviation of the tractor and the trailer is within the range of a preset threshold value is determined according to the relative pose information of the tractor and the trailer;
the parallel backing module is configured to determine that the tractor and the trailer are in a parallel backing scene and enter a parallel backing automatic docking mode when the fact that the longitudinal axes of the tractor and the trailer are parallel and the lateral deviation of the tractor and the trailer is not within the range of a preset threshold value is determined according to the relative pose information of the tractor and the trailer;
and the herringbone backing module is configured to determine that the tractor and the trailer are in a herringbone backing scene and enter a herringbone backing automatic butt joint mode when the fact that the longitudinal axes of the tractor and the trailer are not parallel is determined according to the relative pose information of the tractor and the trailer.
In this embodiment, optionally, the preset threshold is 0.15 meter.
In this embodiment, optionally, the parallel reverse automatic docking mode in the parallel reverse module is: adopting a two-section arc reversing method according to the Ackerman corner corresponding to the first section arc
Figure BDA0003646996560000111
Ackerman corner corresponding to second segment of arc
Figure BDA0003646996560000112
Generating a tractor steer-by-wire command to cause longitudinal axes of the tractor and the trailer to coincide; ackerman corner
Figure BDA0003646996560000113
And
Figure BDA0003646996560000114
the calculation process specifically includes:
let the radius corresponding to the first arc be R 1 The corresponding radius of the second section of circular arc is R 2 The circle centers of the first section of arc and the second section of arc are respectively arranged at two sides of the middle point of the transverse distance between the tractor and the trailer; then, according to the corresponding position relation, calculating to obtain:
Figure BDA0003646996560000115
in the formula, L 0 The longitudinal distance from the initial backing position of the rear shaft of the tractor to the completion of two-section arc backing is represented, and the delta x represents the transverse deviation between the tractor and the trailer;
so that R 1 ＝R 2 Calculated from the above equation:
Figure BDA0003646996560000121
the ackermann angle corresponding to the first arc
Figure BDA0003646996560000122
Ackerman corner corresponding to second segment of arc
Figure BDA0003646996560000123
Respectively as follows:
Figure BDA0003646996560000124
Figure BDA0003646996560000125
wherein L represents a tractor wheel base.
In this embodiment, optionally, the herringbone reverse module in the herringbone reverse module has the following automatic docking mode: when the herringbone reverse vehicle is arranged, the corresponding ackermann corner is
Figure BDA0003646996560000126
According to calculated Ackerman angle
Figure BDA0003646996560000127
Generating a tractor steer-by-wire command to cause longitudinal axes of the tractor and the trailer to coincide; ackerman corner
Figure BDA0003646996560000128
The formula is as follows:
Figure BDA0003646996560000129
wherein L represents a tractor wheelbase; r represents the radius corresponding to the arc segment of the tractor backing, and the calculation process is as follows:
setting the intersection point of the longitudinal axes of the tractor and the trailer as N, and connecting the central point M of the rear shaft of the tractor and the intersection point N to form a line segment MN; the corresponding origin of the arc section of the tractor for backing is O 1 Then:
R＝MN·tan∠O 1 NM
in the formula (I), the compound is shown in the specification,
Figure BDA00036469965600001210
theta is the angle between the tractor and the longitudinal axis of the trailer.
The function of the system for controlling the electric tractor and the trailer to realize the large-angle docking according to this embodiment can be described by the method for controlling the electric tractor and the trailer to realize the large-angle docking, and therefore, a detailed portion in this embodiment may be referred to the above method embodiment, and is not described herein again.
While the invention has been described with respect to a limited number of embodiments, those skilled in the art, having benefit of this description, will appreciate that other embodiments can be devised which do not depart from the scope of the invention as described herein. The present invention has been disclosed with respect to the scope of the invention, which is to be considered as illustrative and not restrictive, and the scope of the invention is defined by the appended claims.

Claims (10)

1. The utility model provides a method for controlling electric tractor and trailer to realize wide-angle butt joint, its characterized in that, according to the different scenes that tractor and trailer were located, makes the tractor reverse according to different automatic butt joint modes respectively to make tractor and trailer longitudinal axis coincidence before the butt joint, concrete process includes:
judging whether the longitudinal axes of the tractor and the trailer are parallel or not according to the relative pose information of the tractor and the trailer, and enabling the tractor to be in a backing state;
if the longitudinal axes of the tractor and the trailer are parallel, judging whether the transverse deviation of the tractor and the trailer is within the range of a preset threshold value, if so, determining that the tractor and the trailer are in a linear reversing scene, and entering a linear reversing automatic butt joint mode; if the distance is not within the range of the preset threshold value, the tractor and the trailer are determined to be in a parallel reversing scene, and the automatic parallel reversing butt joint mode is entered;
and if the longitudinal axes of the tractor and the trailer are not parallel, determining that the tractor and the trailer are in a herringbone reversing scene, and entering a herringbone reversing automatic butt joint mode.
2. The method for controlling the electric tractor and the trailer to realize the large-angle butt joint according to claim 1, wherein the preset threshold value is 0.15 m.
3. The method for controlling the electric tractor and the trailer to realize the large-angle docking according to the claim 1 or 2, characterized in that the parallel reverse automatic docking mode is as follows: adopting a two-section arc reversing method according to the Ackerman corner corresponding to the first section arc
Figure FDA0003646996550000011
Ackerman corner corresponding to second segment of arc
Figure FDA0003646996550000012
Generating a tractor steer-by-wire command to cause longitudinal axes of the tractor and the trailer to coincide; ackerman corner
Figure FDA0003646996550000013
And
Figure FDA0003646996550000014
the calculation process specifically includes:
let the radius corresponding to the first arc be R 1 The corresponding radius of the second section of circular arc is R 2 The circle centers of the first section of arc and the second section of arc are respectively arranged at two sides of the middle point of the transverse distance between the tractor and the trailer; then, according to the corresponding position relation, calculating to obtain:
Figure FDA0003646996550000015
in the formula, L 0 The longitudinal distance from the initial backing position of the rear shaft of the tractor to the completion of two-section arc backing is represented, and the delta x represents the transverse deviation between the tractor and the trailer;
so that R 1 ＝R 2 Calculated from the above equation:
Figure FDA0003646996550000016
the ackermann angle corresponding to the first arc
Figure FDA0003646996550000017
Ackerman corner corresponding to second segment of arc
Figure FDA0003646996550000018
Respectively as follows:
Figure FDA0003646996550000019
Figure FDA0003646996550000021
in the formula, L represents a truck wheel base.
4. The method for controlling the electric tractor and the trailer to realize the large-angle butt joint according to the claim 1 or 2, wherein the herringbone reverse automatic butt joint mode is as follows: when reverse driving is carried out by arranging herringboneCorresponding Ackerman angles of
Figure FDA0003646996550000022
According to calculated Ackerman angle
Figure FDA0003646996550000023
Generating a tractor steer-by-wire command to cause longitudinal axes of the tractor and the trailer to coincide; ackerman corner
Figure FDA0003646996550000024
The formula is as follows:
Figure FDA0003646996550000025
wherein L represents a tractor wheelbase; r represents the radius corresponding to the arc segment of the tractor backing, and the calculation process is as follows:
setting the intersection point of the longitudinal axes of the tractor and the trailer as N, and connecting the central point M of the rear shaft of the tractor and the intersection point N to form a line segment MN; the corresponding origin of the arc section of the tractor for backing is O 1 And then:
R＝MN·tan∠O 1 NM
in the formula (I), the compound is shown in the specification,
Figure FDA0003646996550000026
theta is the angle between the tractor and the longitudinal axis of the trailer.
5. The method for controlling the electric tractor and the trailer to realize the large-angle butt joint according to the claim 1 or 2, wherein the straight-line reverse automatic butt joint mode is as follows: and finely adjusting the front wheel corner of the tractor according to the transverse deviation of the tractor and the trailer and the included angle of the longitudinal axes of the two vehicles, so that the longitudinal axes of the tractor and the trailer are overlapped.
6. A method of controlling an electric tractor and trailer to effect a wide angle dock according to claim 1 or 2, characterised in that after reversing in the automatic dock mode has been completed, i.e. the longitudinal axes of the tractor and trailer have been brought together, the automatic dock mode is disengaged, automatic reverse of the tractor and docking with the trailer is completed.
7. A system for controlling an electric tractor and a trailer to realize large-angle butt joint is characterized in that the system enables the tractor to back up according to different automatic butt joint modes respectively according to different scenes where the tractor and the trailer are located, so that the longitudinal axes of the tractor and the trailer are overlapped before butt joint; the method comprises the following steps:
a relative pose acquisition module configured to acquire relative pose information of the tractor and the trailer;
the linear reversing module is configured to determine that the tractor and the trailer are in a linear reversing scene and enter a linear reversing automatic docking mode when the fact that the longitudinal axes of the tractor and the trailer are parallel and the transverse deviation of the tractor and the trailer is within the range of a preset threshold value is determined according to the relative pose information of the tractor and the trailer;
the parallel backing module is configured to determine that the tractor and the trailer are in a parallel backing scene and enter a parallel backing automatic docking mode when the fact that the longitudinal axes of the tractor and the trailer are parallel and the lateral deviation of the tractor and the trailer is not within the range of a preset threshold value is determined according to the relative pose information of the tractor and the trailer;
and the herringbone backing module is configured to determine that the tractor and the trailer are in a herringbone backing scene and enter a herringbone backing automatic butt joint mode when the fact that the longitudinal axes of the tractor and the trailer are not parallel is determined according to the relative pose information of the tractor and the trailer.
8. The system for controlling the large-angle docking of the electric tractor and the trailer according to claim 7, wherein the preset threshold is 0.15 m.
9. The system for controlling the large-angle butt joint of the electric tractor and the trailer according to claim 7 or 8, wherein the parallel reversing moduleThe automatic parallel reversing butt joint mode is as follows: adopting a two-section arc reversing method according to the Ackerman corner corresponding to the first section arc
Figure FDA0003646996550000031
Ackerman corner corresponding to second segment of arc
Figure FDA0003646996550000032
Generating a tractor steer-by-wire command to cause longitudinal axes of the tractor and the trailer to coincide; ackerman corner
Figure FDA0003646996550000033
And
Figure FDA0003646996550000034
the calculation process specifically includes:
let the radius corresponding to the first arc be R 1 The corresponding radius of the second section of circular arc is R 2 The circle centers of the first section of arc and the second section of arc are respectively arranged at two sides of the middle point of the transverse distance between the tractor and the trailer; then, according to the corresponding position relation, calculating to obtain:
Figure FDA0003646996550000035
in the formula, L 0 The longitudinal distance from the initial backing position of the rear shaft of the tractor to the completion of two-section arc backing is represented, and the delta x represents the transverse deviation between the tractor and the trailer;
so that R 1 ＝R 2 Calculated from the above equation:
Figure FDA0003646996550000036
the ackermann angle corresponding to the first arc
Figure FDA00036469965500000310
Ackerman corner corresponding to second segment of arc
Figure FDA0003646996550000037
Respectively as follows:
Figure FDA0003646996550000038
Figure FDA0003646996550000039
in the formula, L represents a truck wheel base.
10. The system for controlling the electric tractor and the trailer to realize the large-angle docking according to the claim 7 or 8, wherein the herringbone reverse module is characterized in that the herringbone reverse automatic docking mode comprises the following steps: when the herringbone reverse vehicle is arranged, the corresponding ackermann corner is
Figure FDA00036469965500000311
According to calculated Ackerman angle
Figure FDA00036469965500000312
Generating a tractor steer-by-wire command to cause longitudinal axes of the tractor and the trailer to coincide; ackerman corner
Figure FDA00036469965500000313
The formula is as follows:
Figure FDA0003646996550000041
wherein L represents a tractor wheelbase; r represents the radius corresponding to the arc segment of the tractor backing, and the calculation process is as follows:
setting the intersection point of the longitudinal axes of the tractor and the trailer as N, and connecting the central point M of the rear shaft of the tractor and the intersection point N to form a line segment MN; traction apparatusThe corresponding original point of the circular arc section for guiding and backing is O 1 And then:
R＝MN·tan∠O 1 NM
in the formula (I), the compound is shown in the specification,
Figure FDA0003646996550000042
theta is the angle between the tractor and the longitudinal axis of the trailer.
CN202210533626.3A 2022-05-17 2022-05-17 Method and system for controlling electric tractor and trailer to realize large-angle butt joint Pending CN114820771A (en)

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