CN115303240B

CN115303240B - Braking method, braking device, electronic equipment and storage medium

Info

Publication number: CN115303240B
Application number: CN202210771076.9A
Authority: CN
Inventors: 田晓生; 周文凯
Original assignee: Uisee Technologies Beijing Co Ltd
Current assignee: Uisee Technologies Beijing Co Ltd
Priority date: 2022-06-30
Filing date: 2022-06-30
Publication date: 2023-06-23
Anticipated expiration: 2042-06-30
Also published as: CN115303240A

Abstract

The embodiment of the disclosure discloses a braking method, a braking device, electronic equipment and a storage medium, wherein the braking method comprises the following steps: determining the pose of each section of trailer pulled by the tractor in the driving process according to a kinematic model of the motion of the tractor pulling the trailer; determining a target maximum deceleration based on constraint conditions of friction force stress balance according to the pose and the kinematic model of each section of trailer; determining that the tractor uniformly decelerates from the current position to a target position where the relative speed with the obstacle is zero at a target maximum deceleration; determining an absolute safety position and an expected safety position based on the position of the obstacle, an absolute safety threshold and an expected safety threshold, wherein the absolute safety threshold is less than the expected safety threshold; determining a target deceleration from a relationship between the target position and the absolute and desired guard positions; the tractor is controlled to perform uniform deceleration braking from the current position at the target deceleration. The probability of extrusion and folding between the dragees during braking is reduced, and the safety during braking is improved.

Description

Braking method, braking device, electronic equipment and storage medium

Technical Field

The disclosure relates to the technical field of dragees, and in particular relates to a braking method, a braking device, electronic equipment and a storage medium.

Background

The logistics scene is an important application scene of the automatic driving technology in the landing, and the automatic driving vehicles in the scene need to drag one or more dragees to complete the cargo transportation task. In the process of transporting goods by the traction drawers, once a dangerous scene is met, the traction vehicles need to be braked in a planning mode to avoid dangerous collision, but unreasonable braking can cause extrusion and folding between the drawers, and the goods transportation safety is affected.

Aiming at the problem that extrusion folding occurs during the braking of a trailer, two solutions exist at present: the first scheme is to improve the hardware characteristics of the trailer, reduce the gravity center of the trailer as much as possible by optimizing the structure of the trailer, ensure that the stress of the trailer is concentrated on the central axis as much as possible when the trailer is in straight running, and increase the buffer transposition at the joint of the trailer, thereby reducing the probability of extrusion deformation when the trailer is braked by reducing the impact force and the like. However, since this solution requires the design and manufacturing stages of the trailer, it can only be used in the design stage of the trailer, and it is difficult to apply it to the trailer that has been put into use, and thus the solution is greatly limited in practical use. The second scheme is to carry out speed limiting running according to the number of the dragees, and according to the theory that the lower the number of the dragees is, the more extrusion deformation is easy to occur under the same braking condition, and the lower the speed is, the smaller the maximum braking required by dangerous scenes is met, the vehicle speed limiting is carried out according to the principle that the higher the number of the dragees is, the lower the highest speed limit is. However, the rough speed reduction reduces the transportation efficiency of the automatic driving logistics project on one hand, and on the other hand, because the speed limit and the folding of the dragees are not directly related, the situation that the dragees are extruded and folded due to the unbalanced braking can still occur even after the speed limit.

Therefore, there is a continuing need to develop other solutions to the problem of squeeze folding when the trailer brakes.

Disclosure of Invention

In order to solve the technical problems or at least partially solve the technical problems, the embodiments of the present disclosure provide a braking method, a device, an electronic device, and a storage medium, which reduce the probability of extrusion folding between the tugs during braking, and improve the safety during braking.

In a first aspect, embodiments of the present disclosure provide a braking method, the method comprising:

determining the pose of each section of trailer pulled by the tractor in the driving process according to a kinematic model of the motion of the tractor pulling the trailer;

determining a target maximum deceleration based on constraint conditions of friction force stress balance according to the pose of each section of trailer and the kinematic model;

determining an obstacle closest to the tractor in the running direction according to the planned path of the tractor;

determining a target position where the tractor uniformly decelerates from the current position to zero relative speed to the obstacle at the target maximum deceleration;

determining an absolute safety position and a desired safety position based on a position of the obstacle, an absolute safety threshold, and a desired safety threshold, wherein the absolute safety threshold is less than the desired safety threshold;

Determining a target deceleration from a relationship between the target position and the absolute guard position and the desired guard position;

and controlling the tractor to perform uniform deceleration braking from the current position at the target deceleration.

In a second aspect, embodiments of the present disclosure also provide a brake apparatus, the apparatus comprising:

the first determining module is used for determining the pose of each section of trailer pulled by the tractor in the driving process according to a kinematic model of the motion of the tractor pulling the trailer;

the second determining module is used for determining a target maximum deceleration based on constraint conditions of friction force stress balance according to the pose of each section of trailer and the kinematic model;

a third determining module, configured to determine an obstacle closest to the tractor in a driving direction according to a planned path of the tractor;

a fourth determining module, configured to determine that the tractor uniformly decelerates from a current position to a target position where a relative speed with the obstacle is zero at the target maximum deceleration;

a fifth determining module, configured to determine an absolute safety position and a desired safety position based on a position where the obstacle is located, an absolute safety threshold, and a desired safety threshold, where the absolute safety threshold is less than the desired safety threshold;

A sixth determination module for determining a target deceleration from a relationship between the target position and the absolute guard position and the desired guard position;

and a seventh determining module for controlling the tractor to perform uniform deceleration braking from the current position at the target deceleration.

In a third aspect, embodiments of the present disclosure further provide an electronic device, including: one or more processors; a storage means for storing one or more programs; when the one or more programs are executed by the one or more processors, the one or more processors are caused to implement the braking method as described above.

In a fourth aspect, the disclosed embodiments also provide a computer readable storage medium having stored thereon a computer program which when executed by a processor implements a braking method as described above.

According to the braking method provided by the embodiment of the disclosure, firstly, the maximum target deceleration allowed when extrusion folding does not occur between the dragees is determined based on constraint conditions of friction force stress balance, then the tractor is simulated to uniformly decelerate from the current position to the target position where the relative speed of the tractor and the obstacle is zero at the maximum target deceleration, finally, the final braking deceleration (namely the target deceleration) is determined according to the relation among the target position, the absolute safety position, the expected safety position and the position where the obstacle is located, and the tractor is controlled to uniformly decelerate and brake at the final braking deceleration. The probability of extrusion and folding between the dragees during braking is reduced, and the safety during braking is improved.

Drawings

The above and other features, advantages, and aspects of embodiments of the present disclosure will become more apparent by reference to the following detailed description when taken in conjunction with the accompanying drawings. The same or similar reference numbers will be used throughout the drawings to refer to the same or like elements. It should be understood that the figures are schematic and that elements and components are not necessarily drawn to scale.

FIG. 1 is a schematic illustration of a multi-section trailer in an embodiment of the present disclosure, with squeezing and folding due to improper braking;

FIG. 2 is a flow chart of a braking method in an embodiment of the present disclosure;

FIG. 3 is a schematic diagram of a kinematic model of the movement of a tractor traction trailer in an embodiment of the present disclosure;

FIG. 4 is a schematic illustration of an absolute safety position and a desired safety position in an embodiment of the present disclosure;

FIG. 5 is a schematic diagram of a kinematic model of a full trailer in an embodiment of the present disclosure;

FIG. 6 is a schematic diagram of a kinematic model of a semi-trailer in an embodiment of the present disclosure;

FIG. 7 is a schematic view of a default baffle in an embodiment of the present disclosure;

FIG. 8 is a schematic diagram of determining a measured value of a center coordinate of a rear axle of a first section of trailer and a measured value of a heading angle according to a corresponding point cloud on a preset baffle in an embodiment of the disclosure;

FIG. 9 is a schematic structural view of a brake device in an embodiment of the present disclosure;

fig. 10 is a schematic structural diagram of an electronic device in an embodiment of the disclosure.

Detailed Description

Embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. While certain embodiments of the present disclosure have been shown in the accompanying drawings, it is to be understood that the present disclosure may be embodied in various forms and should not be construed as limited to the embodiments set forth herein, but are provided to provide a more thorough and complete understanding of the present disclosure. It should be understood that the drawings and embodiments of the present disclosure are for illustration purposes only and are not intended to limit the scope of the present disclosure.

It should be noted that the terms "first," "second," and the like in this disclosure are merely used to distinguish between different devices, modules, or units and are not used to define an order or interdependence of functions performed by the devices, modules, or units.

The names of messages or information interacted between the various devices in the embodiments of the present disclosure are for illustrative purposes only and are not intended to limit the scope of such messages or information.

The logistics scene is an important application scene of the automatic driving technology in the landing, and the automatic driving vehicles in the scene need to drag one or more dragees to complete the cargo transportation task. In the process of transporting goods by the traction hopper of the traction vehicle, once a dangerous scene is met, the traction vehicle needs to be braked in a planning mode to avoid dangerous collision, but unreasonable braking can cause extrusion and folding between the traction hoppers, and the goods transportation safety is affected. A schematic diagram of a multi-section trailer as shown in fig. 1 is extruded and folded due to unreasonable braking.

In view of the above problems, the embodiments of the present disclosure provide a braking method, which aims to reduce the probability of extrusion and folding between each section of trailer towed by a tractor as much as possible on the premise of ensuring that the tractor does not collide with an obstacle by determining reasonable braking deceleration when the obstacle exists in front of the tractor, thereby improving the running safety of the vehicle.

Fig. 2 is a flow chart of a braking method in an embodiment of the present disclosure. The method may be performed by a braking device, which may be implemented in software and/or hardware, which may be configured in an electronic apparatus. As shown in fig. 2, the method specifically includes the following steps:

And 210, determining the pose of each section of trailer pulled by the tractor in the driving process according to a kinematic model of the motion of the tractor pulling the trailer.

And 220, determining a target maximum deceleration based on constraint conditions of friction force stress balance according to the pose of each section of trailer and the kinematic model.

Illustratively, determining the target maximum deceleration based on the constraint condition of friction force stress balance according to the pose of each section of the trailer and the kinematic model comprises:

and determining the selectable maximum deceleration corresponding to each section of the trailer based on the constraint condition of friction force and stress balance according to the pose of each section of the trailer and the kinematic model, and determining the target maximum deceleration according to the selectable maximum deceleration corresponding to each section of the trailer.

In some embodiments, the above-described determination of the optional maximum deceleration is described taking, as an example, the determination of the optional maximum deceleration corresponding to the current section trailer (the current section trailer is any one of the sections of the trailer):

step 221: and respectively determining second acting force, applied to the rear shaft of the current section trailer, along the axial direction of the rear shaft and third acting force, applied to the front shaft of the current section trailer, along the axial direction of the front shaft of the current section trailer according to the first acting force, the pose of the current section trailer, the pose of the rear section trailer and the kinematic model of the current section trailer applied to the current section trailer of the current section trailer.

Step 222: and determining a first maximum deceleration according to the second acting force and determining a second maximum deceleration according to the third acting force based on the constraint condition of friction force stress balance.

For convenience of description, the current section of trailer is denoted as a kth section of trailer, the rear section of trailer which is towed by the current section of trailer is denoted as a kth+1 section of trailer, and reference is made to a schematic diagram of a kinematic model of the motion of a tractor traction trailer as shown in fig. 3, wherein reference numeral 20 represents a tractor, and the kth section of trailer 10_k and the kth+1 section of trailer 10_k+1 are connected through a trailer hook 11, that is, a trailer rod 12 of the kth+1 section of trailer is connected with the trailer hook 11 of the kth section of trailer. The heading angle of the towing rod of the kth section of towing bucket is theta_f (k), the heading angle of the vehicle body is theta_r (k), and the heading angle of the towing rod of the kth+1 section of towing bucket is theta_f (k+1).

When the tractor is braked, the stress analysis of the kth section of the tractor is as follows when the tractor is braked, wherein the accelerations of the sections of the tractor are the same:

the force mark f_integral (k+1) which acts on the kth section trailer at the kth section trailer hook 11 along the direction of the trailer rod 12 of the kth section trailer is the first acting force of the rear section trailer which is pulled by the current section trailer and acts on the current section trailer, and since the force is generated in the speed reduction process of the rear section trailer, f_integral (k+1) can be expressed as the following formula (1):

f_integral_(k+1)＝m_integral(k+1)*max_dec_r(k)(1)

Where m_integral (k+1) is the cumulative mass transferred to the kth section of the trailer (including the trailer directly towed by the kth section of the trailer, e.g., the kth+1 section of the trailer, and the trailer indirectly towed by the kth section of the trailer, e.g., the kth+2 section, the kth+3 section of the trailer, etc.), the cumulative mass can be calculated by the included angle between the sections of the trailer. For example, assuming that there is only one section of trailer behind the kth section of trailer, namely the kth+1th section of trailer, the mass of each section of trailer is m, the included angle between the kth section of trailer and the kth+1th section of trailer is 0, namely the kth section of trailer and the kth+1th section of trailer travel on a straight line, and the accumulated mass transferred to the kth section of trailer at this time is m+m=2m; if two sections of dragees are arranged behind the kth section of dragee, the accumulated mass transferred to the kth section of dragee is m+m+m=3m.

Further, if there is only one section of trailer behind the kth section of trailer, that is, the kth+1 section of trailer, the mass of each section of trailer is m, the included angle between the heading of the kth+1 section of trailer body and the heading of the trailer rod is alpha_f (k+1), the included angle between the heading of the kth+1 section of trailer rod and the heading of the kth+1 section of trailer body is alpha_r (k) (as shown in fig. 3), and the accumulated mass transferred to the kth section of trailer at this time is m+m×cos (alpha_f (k+1))×cos (alpha_r (k)).

The calculation mode is similar to the above when there are multiple sections of dragees behind the kth segment of dragees, for example, when there are two sections of dragees behind the kth segment of dragees, the kth+1 section of dragees and the kth+2 section of dragees are respectively, then the mass of the kth+2 section of dragees transferred to the kth+1 section of dragees is determined according to the calculation mode, at this time, the mass of the kth+1 section of dragees is the sum of the mass transferred by the m and the kth+2 section of dragees, and the mass of the kth+1 section of dragees transferred to the kth section of dragees is determined based on the mass.

Further, according to newton's second law f=ma, the above formula (1) can be obtained, where max_dec_r (k) in formula (1) is the first maximum deceleration of the kth section trailer, and f_integral_ (k+1) is the first acting force applied to the current section trailer by the rear section trailer that is pulled by the current section trailer, and the first maximum deceleration is an unknown quantity and needs to be solved based on a constraint condition of friction force stress balance.

Further, a second acting force f_frc_r (k) along the axial direction of the rear shaft of the kth section trailer and a third acting force f_frc_f (k) along the axial direction of the front shaft of the kth section trailer are respectively determined according to the first acting force, the pose of the kth section trailer, the pose of the kth+1 section trailer and the kinematic model shown in fig. 3.

Specifically, the second acting force f_frc_r (k) applied to the rear axle of the kth segment trailer in the axial direction thereof can be expressed as formula (2):

f_frc_r(k)＝f_integral(k+1)*sin(alpha_r(k))*K (2)

wherein alpha_r (k) is the angle between the kth section trailer heading theta_r (k) and the kth+1 section trailer front axle heading (i.e., the tow bar heading) theta_f (k+1), and alpha_r (k) can be expressed as formula (3):

alpha_r(k)＝|theta_r(k)–theta_f(k+1)| (3)

where K is a lever coefficient of an axial component force of the kth section trailer acting on the kth section trailer hook along the rear axle thereof, and means that when a force required for braking the rear section trailer (for example, the kth+1 section trailer) is unbalanced by an axial force of the rear axle of an adjacent front section trailer (for example, a component force in the axial direction of the rear axle of the kth section trailer), the force required for braking the rear section trailer is amplified, because the force required for braking the rear section trailer is amplified due to the presence of the front section trailer hook, and the degree to which the force required for braking the rear section trailer is amplified is defined as a lever coefficient K, which may be expressed as formula (4):

K＝(wheel_base+hook_length)/wheel_base (4)

where, wheel_base is the wheelbase of the kth section trailer, as shown at c1 in FIG. 3, and hook_length is the hitch length of the kth section trailer, as shown at h1 in FIG. 3.

Assuming that the mass of each section of the trailer is m and that the weight average acts on the front and rear shafts, the maximum static friction force f_frc_r (k) of the rear shaft of the kth section of the trailer can be expressed as formula (5):

F_frc_r(k)＝m*g*u/2 (5)

Wherein g is gravity acceleration, and u is the static friction coefficient between the trailer wheels and the ground.

Under the limit condition that the rear axle of the kth section trailer does not slide along the axial direction, f_frc_r (k) and f_frc_r (k) meet the equal constraint relation, namely the constraint condition based on the stress balance of friction force can obtain the equation relation of the formula (6):

F_frc_r(k)＝f_frc_r(k) (6)

the first maximum deceleration max_dec_r (k) when the rear axle of the kth section trailer does not slide in the axial direction can be obtained by combining the above formulas (1) to (6):

similarly, the component force f_b_r (k) of the kth segment trailer acting longitudinally forward (i.e., in the direction of the central axis) of the kth segment trailer can be expressed as formula (7):

f_b_r(k)＝f_integral(k+1)*cos(alpha_r(k)) (7)

the force f_b (k) applied by the rear axle of the kth section trailer to its front axle can be expressed as formula (8):

f_b(k)＝f_b_r(k)+m*max_dec_f(k) (8)

further, the third acting force f_frc_f (k) in the axial direction applied to the front axle of the kth section trailer may be expressed as formula (9):

f_frc_f(k)＝f_b(k)*sin(alpha_f(k)) (9)

wherein alpha_f (k) is the difference between the heading of the front axle and the heading of the rear axle of the kth section trailer, and can be expressed as formula (10):

alpha_f(k)＝|theta_f(k)-theta_r(k)|(10)

since the weight of the trailer is m and the weight average acts on the front and rear axles, the maximum static friction force f_frc_f (k) of the front axle of the kth section of trailer can be expressed as formula (11):

F_frc_f(k)＝m*g*u/2 (11)

Under the limit condition that the front axle of the kth section trailer does not slide along the axial direction, the f_frc_f (k) and the f_frc_f (k) meet the equal constraint relation, namely the constraint condition based on the stress balance of friction force can obtain the equation relation of the formula (12):

F_frc_f(k)＝f_frc_f(k)(12)

the second maximum deceleration max_dec_f (k) when the front axle of the kth section trailer does not slide in the axial direction can be obtained by combining the above formulas (7) to (12):

the thrust force f_integral_ (k) of the kth section trailer on the kth-1 section trailer hitch can be expressed as:

f_integral(k)＝f_b(k)*cos(alpha_f(k))

so far, the analysis process of the maximum deceleration at which the transverse slip does not occur in the case where the kth section trailer receives the kth+1 section trailer braking thrust and the braking thrust transmitted to the kth-1 section trailer is ended. The first maximum deceleration and the second maximum deceleration corresponding to the kth section of the trailer are calculated in a similar manner to those of the first maximum deceleration and the second maximum deceleration corresponding to the kth section of the trailer.

In general terms, a second force f_frc_r (k) is determined from a first force f_integral_ (k+1), a body heading theta_r (k) of a current section trailer, a front axle heading theta_f (k+1) of the rear section trailer, a wheelbase of the current section trailer, a hook length hook_length of the current section trailer, wherein the wheelbase of the current section trailer, and the length hook_length of the current section trailer are determined based on the kinematic model, and the current section trailer is coupled to the rear section trailer by the hook; determining a fourth acting force f_b_r (k) applied to the current section trailer along the central axis direction according to the first acting force f_integral_ (k+1), the vehicle body heading theta_r (k) of the current section trailer and the front axle heading theta_f (k+1) of the rear section trailer; and determining the third acting force f_frc_f (k) applied to the front axle of the current section trailer by the rear axle of the current section trailer and axially along the front axle according to the fourth acting force f_b_r (k), the front axle heading theta_f (k) and the rear axle heading theta_r (k) of the current section trailer.

Step 223: and determining the optional maximum deceleration corresponding to the current section trailer according to the first maximum deceleration and the second maximum deceleration.

Optionally, determining the smaller one of the first maximum deceleration and the second maximum deceleration as the optional maximum deceleration corresponding to the current section trailer; or determining the average value of the first maximum deceleration and the second maximum deceleration as the selectable maximum deceleration corresponding to the current section trailer.

Step 224: and determining the target maximum deceleration according to the selectable maximum deceleration corresponding to each section of trailer.

Optionally, the determining the target maximum deceleration according to the selectable maximum deceleration corresponding to each section of trailer respectively includes:

and determining the minimum of the selectable maximum decelerations corresponding to the various sections of the tugs as the target maximum deceleration.

Or determining the average value of the selectable maximum deceleration corresponding to each section of trailer as the target maximum deceleration.

Step 230, determining an obstacle closest to the tractor in the driving direction according to the planned path of the tractor.

The method comprises the steps of determining an obstacle in front of the tractor, wherein the obstacle is closest to the front of the tractor, braking the tractor to a certain extent is needed to prevent the tractor from colliding with the obstacle, and the braking deceleration of the tractor is needed to be reasonably determined to reduce the probability of folding due to braking among all the dragees towed by the tractor as much as possible.

Step 240, determining that the tractor uniformly decelerates from the current position to a target position at which the relative speed with the obstacle is zero at the target maximum deceleration.

Step 250, determining an absolute safety position and a desired safety position based on the position of the obstacle, an absolute safety threshold, and a desired safety threshold, wherein the absolute safety threshold is less than the desired safety threshold.

Illustratively, the determining the absolute safety position and the desired safety position based on the position of the obstacle, the absolute safety threshold, and the desired safety threshold includes:

determining a position on a planned path between the tractor and the obstacle, the distance between the position and the obstacle being the absolute safety threshold, as the absolute safety position;

a position on a planned path between the tractor and the obstacle, at which a distance from the obstacle is the desired safety threshold, is determined as the desired safety position.

Alternatively, referring to a schematic diagram of an absolute safety position and a desired safety position shown in fig. 4, specifically, assuming that the absolute safety threshold is 1 meter, the desired safety threshold is 2 meters, the position where the obstacle is located is taken as the origin of coordinates, the forward direction of the planned path of the tractor is the positive direction of the horizontal axis, that is, the traveling direction of the tractor is the positive direction of the horizontal axis, the horizontal axis represents the distance, the vertical axis represents time, the position where the obstacle is located at a distance of 1 meter from the tractor s5 is determined as the absolute safety position s1, and the position where the obstacle is located at a distance of 2 meters from the tractor s5 is determined as the desired safety position s3.

Step 260, determining a target deceleration from the target position and the relation between the absolute guard position and the desired guard position.

Referring to fig. 4, specifically, if the target position is between the current position s5 and the desired safe position s3, a third deceleration dec_3 is determined as the target deceleration, wherein the third deceleration is determined based on the current vehicle speed ego _v of the tractor, the current position s5, and the desired safe position s 3; in particular, the method comprises the steps of,

and if the target position is between the desired guard position s3 and the absolute guard position s1, determining the target maximum deceleration as the target deceleration.

If the target position exceeds the absolute guard position, a first deceleration dec_1 is determined as the target deceleration, wherein the first deceleration dec_1 is determined based on a current vehicle speed ego _v of the tractor, a current position s5, and the absolute guard position s1, specifically,

in other words, as shown in fig. 4, the forward direction of the planned route is the horizontal forward direction with the closest obstacle on the planned route in front of the host vehicle as the reference origin, the position of the tractor in this coordinate system is s5, the absolute safety distance between the host vehicle and the preceding vehicle (the minimum safety distance between the host vehicle and the preceding vehicle at any time) is-s 1, and the desired safety distance between the host vehicle and the preceding vehicle (the distance desired to be stably maintained when the host vehicle stably follows the preceding vehicle) is-s 3, and it is known from the theory that |s3| > |s1|. In this coordinate system, the vehicle speed of the host vehicle is ego _vel, and it is known from physical definition that only ego _vel >0 needs to be considered for carrying out the trailer brake folding problem, so ego _vel >0 is set.

In fig. 4, a curve c1 represents a track curve of the vehicle at an absolute safety position s1 by uniformly decelerating and stopping at a deceleration dec_1, c3 represents a track curve of the vehicle at a desired safety position s3 by uniformly decelerating and stopping at a deceleration dec_3, and three conditions of c4, c2 and c0 are provided for the track curve of the vehicle by ensuring a target maximum deceleration max_dec_of_trailers braking when the trailer is not braked by taking the two track curves as references. c0 corresponds to the fact that the vehicle brakes according to the target maximum deceleration, and the vehicle inevitably collides with an obstacle; c2, braking the corresponding vehicle according to the target maximum deceleration, wherein the vehicle can exceed the expected safe position and stop before reaching the absolute safe position; c4 corresponds to the vehicle braking according to the target maximum deceleration, and the vehicle can be braked before reaching the expected safe position.

For the scenario of c0, the host vehicle plans the deceleration of dec_1. The collision is avoided, and simultaneously, larger braking is avoided as much as possible, so that the probability of folding the trailer is reduced as much as possible under the condition that the folding of the trailer cannot be avoided.

For the scenario of c2, the host vehicle plans a deceleration of max_dec_of_brakes. The trailer is prevented from being braked, squeezed and folded while dangerous collision is avoided. For the scenario of c4, the host vehicle plans the deceleration of dec_3, and ensures that the trailer is not folded by braking extrusion while ensuring that the vehicle is parked at the desired safe position.

The planned deceleration dec, i.e., the target deceleration, corresponding to the host vehicle may be expressed as follows:

in the method, in the process of the invention,

in other embodiments, the determining the target deceleration from the target position and the relationship between the absolute guard position and the desired guard position includes:

if the target position is between the expected safety position and the absolute safety position, updating the expected safety position according to the distance between the target position and the position of the obstacle, and obtaining an updated expected safety position;

the target deceleration is determined based on a preset linear constraint relationship, wherein the preset linear constraint relationship is determined based on a current vehicle speed of the tractor, the current position, the absolute safety position, the updated desired safety position, and the target position.

Illustratively, the preset linear constraint relationship includes:

wherein s2 represents the target position, s3 represents the updated desired safe position, s1 represents the absolute safe position, max_dec represents the target deceleration, s5 represents the current position, ego _vel represents the current vehicle speed of the tractor.

Step 270, controlling the tractor to perform uniform deceleration braking from the current position at the target deceleration.

According to the braking method provided by the embodiment, firstly, the maximum target deceleration allowed when extrusion folding does not occur between the dragees is determined based on constraint conditions of friction force stress balance, then the tractor is simulated to uniformly decelerate from the current position to the target position where the relative speed of the tractor and the obstacle is zero at the maximum target deceleration, finally, the final braking deceleration (namely, the target deceleration) is determined according to the relation among the target position, the absolute safety position, the expected safety position and the position where the obstacle is located, and the tractor is controlled to uniformly decelerate and brake at the final braking deceleration. The probability of extrusion and folding between the dragees during braking is reduced, and the safety during braking is improved.

On the basis of the embodiment, the determining the pose of each section of trailer towed by the tractor in the driving process according to the kinematic model of the motion of the tractor towing the trailer comprises the following steps:

step 211, determining a measured value of a central coordinate of a rear axle of a first section trailer towed by the tractor and a measured value of a heading angle based on associated data of a sensor installed on the tractor.

Optionally, determining a measured value of a central coordinate of a rear axle of a first section trailer towed by the tractor and a measured value of a heading angle based on image data shot by a camera mounted on the tractor for the trailer; or determining a measured value of a central coordinate of a rear axle of a first section of trailer towed by the tractor and a measured value of a heading angle based on scanning data of the first section of trailer by a laser radar installed on the tractor.

Further description will be given by taking as an example a measurement value of a center coordinate of a rear axle of a first section trailer towed by a tractor and a measurement value of a heading angle based on scanning data of the first section trailer by a laser radar mounted on the tractor.

In one embodiment, the measured value of the central coordinate of the rear axle of the first section of trailer towed by the tractor and the measured value of the heading angle can be determined by means of a kinematic model of the trailer and the scanning data of the laser radar installed on the tractor for the first section of trailer. The first section of trailer towed by the tractor can be further divided into a full trailer and a half trailer, and correspondingly, reference may be made to a schematic diagram of a kinematic model of the full trailer as shown in fig. 5 and a schematic diagram of a kinematic model of the half trailer as shown in fig. 6.

In FIG. 5, θ ₀ ，θ ₁ And theta ₂ Respectively representing heading angles omega of the tractor 320, the front axle 312 of the full trailer and the rear axle 311 of the full trailer ₀ ，ω ₁ And omega ₂ The course angle change rates of the tractor 320, the full trailer front axle 312, and the full trailer rear axle 311 are shown, respectively. The angle between the tractor 320 and the front axle 312 of the full trailer is

The included angle between the front axle 312 of the full trailer and the rear axle 311 of the full trailer is +.>

l _fr0 And l _fr1 Indicating the wheelbase (i.e., the length marked by reference numeral 313) of the tractor 320 and the full trailer 310, respectively, l _h Represents the distance from the center D of the rear axle of the tractor to the joint A, l _b Representing the distance from the center B of the front axle 312 of the trailer (i.e., the location marked by reference numeral 314) to the attachment point a (i.e., the location marked by reference numeral 321). Delta _f Is the front wheel angle of the tractor 320. v ₀ Is the speed of the rear axle center C of the tractor. v ₁ V is the speed of the center B of the front axle of the full trailer ₂ Is the speed of the center C of the rear axle of the full trailer. (x) ₀ ,y ₀ ) Is the coordinates of the center C of the rear axle of the tractor, (x) ₁ ,y ₁ ) Is the coordinate of the center B of the front axle of the full trailer (x) ₂ ,y ₂ ) Is the coordinate of the center C of the rear axle of the full trailer. The component marked by reference numeral 330 may be referred to as a mop or a connecting bar.

In FIG. 6, θ ₁ And theta ₂ Respectively representing course angles of the rear axles of the tractor and the semi-trailer, wherein the included angle between the tractor and the semi-trailer is

l ₀ For the wheelbase of the tractor, l _t Distance l from center D of rear axle of tractor to joint A ₁ Is the distance from the center C of the rear axle of the half trailer to the joint A. Delta is the front wheel declination of the tractor. v ₁ Is the speed of the rear axle center D of the tractor. v ₂ Is the speed of the center C of the rear axle of the half trailer. (x) ₁ ,y ₁ ) Is the coordinates of the center D of the rear axle of the tractor, (x) ₂ ,y ₂ ) The coordinates of the center C of the rear axle of the semi-trailer, delta is the front wheel deflection angle of the tractor.

On the basis of the kinematic model of the trailer, the determining the measured value of the central coordinate of the rear axle of the first trailer and the measured value of the heading angle of the first trailer towed by the tractor based on the scanning data of the laser radar installed on the tractor for the first trailer comprises the following steps:

determining a corresponding point cloud of laser emitted by the laser radar in a set period on a preset baffle of the first section of trailer, wherein the laser radar is mounted on a tractor roof, and the preset baffle is vertically mounted on the edge of the first section of trailer close to the tractor, and referring to a schematic diagram of a preset baffle shown in fig. 7, for example, wherein the preset baffle 710 is vertically mounted on an edge 721 of the first section of trailer 720 close to the tractor, and the first section of trailer 720 is connected with the tractor through a mop 722, so that the edge 721 is the edge close to the tractor.

And determining a measured value of a central coordinate of the rear axle of the first section of the trailer and a measured value of a heading angle based on the corresponding point cloud, the associated data of the laser radar and the position relation between the preset baffle and the center of the rear axle of the first section of the trailer. Specifically, a straight line parallel to the preset baffle is fitted according to the corresponding point cloud, and a first included angle between the straight line and the rear axle of the tractor is determined; and determining a measured value of a central coordinate of a rear shaft of the first section of the trailer and a measured value of a heading angle according to the first included angle, the associated data of the laser radar and the position relation between the preset baffle and the center of the rear shaft of the first section of the trailer. For example, referring to a schematic diagram of determining a measurement value of a central coordinate of a rear axle of a first section of trailer and a measurement value of a heading angle according to a corresponding point cloud on a preset baffle as shown in fig. 8, a straight line 810 is a straight line fitted according to the corresponding point cloud on the preset baffle, a first included angle α1 between the straight line and a rear axle 821 of a tractor 820, and a second included angle α2 between a central axis 822 of the tractor and a central axis 831 of the first section of trailer 830 is the same as the first included angle α1 according to a positional relationship and a geometric relationship between the preset baffle and the rear axle 821 of the first section of trailer, so that a heading angle of the rear axle center B of the first section of trailer can be obtained. The coordinates of the point O can be determined according to the coordinate information of the corresponding point cloud on the preset baffle, and then the coordinates of the center B of the rear axle of the first section of trailer can be determined by combining the wheelbase 11 of the first section of trailer 830, so as to obtain the measured value of the center coordinates of the rear axle of the first section of trailer and the measured value of the heading angle.

In fig. 8, the half trailer is taken as an example, and the calculation process of the full trailer is the same as that of the half trailer.

Step 212, determining a first running state of the first section of trailer rear axle through an extended kalman filtering algorithm according to the measured value of the central coordinate of the first section of trailer rear axle, the measured value of the heading angle and the kinematic model, wherein the first running state of the first section of trailer rear axle comprises the pose of the first section of trailer rear axle, and specifically, the estimated value of the central coordinate of the first section of trailer rear axle, the estimated value of the heading angle, the estimated value of the running speed and the estimated value of the change rate of the heading angle.

Illustratively, the determining, according to the measured value of the central coordinate of the rear axle of the first section of trailer and the measured value of the heading angle and the kinematic model, the first driving state of the rear axle of the first section of trailer by using an extended kalman filter algorithm includes: determining a measured value of the center coordinates of the rear axle of the first section trailer, a measured value of the speed and the course angle and a change rate of the course angle as a state vector; determining a measured value of the central coordinate of the rear axle of the first section of trailer and a measured value of the course angle as observation vectors; constructing a state equation of an extended Kalman filtering algorithm according to the state vector and a relation determined based on the kinematic model; constructing an observation equation of an extended Kalman filtering algorithm according to the observation vector and the state equation; and determining the first running state of the rear axle of the first section of trailer according to the state equation and the observation equation.

Specifically, for the full trailer, referring to a schematic diagram of a kinematic model of the full trailer as shown in fig. 5, further, the kinematic relationship for the rear axle of the trailer may be represented by the following formula (13):

wherein θ ₂ Indicating the course angle omega of the rear axle of the full trailer ₂ The course angle change rate of the rear axle of the full trailer is represented. v ₂ Is the speed of the center C of the rear axle of the full trailer (x) ₂ ,y ₂ ) Is the coordinate of the center C of the rear axle of the full trailer.

Discretizing the formula (13) to obtain a formula (14):

(14)

in particular, when the vehicle is running straight, the course angle change rate omega of the rear axle of the full trailer is ₂ =0, and the pose equation of the rear axle of the full trailer in this case is shown in the following expression (15):

(15)

similarly, the kinematic relationship of the front axle center of the full trailer can be expressed by the following formula (16):

(16)

wherein θ ₁ Indicating the course angle omega of the front axle of the full trailer ₁ Representing the front of the full trailerThe rate of change of heading angle of the shaft, v ₁ V is the speed of the center B of the front axle of the full trailer ₂ Is the speed of the center C of the rear axle of the full trailer (x) ₁ ,y ₁ ) Is the coordinate of the center B of the front axle of the full trailer.

Discretizing the expression (16) to obtain an expression (17):

/>

also, ω when the vehicle is traveling straight ₁ =0, in which case the pose equation of the front axle of the full trailer is shown in the following expression (18):

(18)

The half trailer has no front axle structure, and the kinematic relationship of the rear axle of the half trailer is the same as that of the rear axle of the full trailer, i.e. the kinematic relationship of the rear axle of the half trailer can be represented by the formulas (13) - (15).

Based on the kinematic relation, the state of the rear axle of the first section of trailer is estimated through an extended Kalman filtering algorithm, so that the first running state of the rear axle of the first section of trailer can be obtained. Because the kinematic relationship of the rear axle of the full trailer is the same as that of the rear axle of the half trailer, when the extended Kalman filtering is carried out on the rear axle of the trailer, the processing logic of the full trailer and the processing logic of the half trailer are the same, and the obtained result is the same.

Specifically, the order state vector is X ₂ ＝[x ₂ y ₂ θ ₂ v ₂ ω ₂ ]The observation vector is:

Y ₂ ＝[x ₂ y ₂ θ ₂ ]the state equation is shown in the following expression (19), and the observation equation is shown in the following expression (20):

X _2,k ＝f ₂ (X _2,k )+Γ _w2 w _2,k-1 (19)

Y _2,k ＝H ₂ X _2,k +v _2,k (20)

wherein f in expression (19) when the vehicle is traveling straight ₂ (X _2,k ) For the above expression (15), when the vehicle is not traveling straight, f ₂ (X _2,k ) Is the expression (14) described above. Γ -shaped structure _w2 ＝I ₅ Representing an identity matrix with dimensions 5 x 5. Observation matrix

w _2,k-1 Representing process noise, v _2,k Representing observed noise. Assuming that the process noise and the observed noise satisfy the Gaussian zero-mean distribution and are independent of each other, the following relation (21) is provided

In which Q ₂ A symmetric covariance matrix representing process noise, R ₂ Representing a symmetric covariance matrix of the observed noise.

Assume an initial value X of a state vector ₂ (0) Obeying Gaussian distribution, the initial variance matrix is

The process of state estimation based on the extended kalman filter algorithm is as follows:

1) Based on the state equation, state prediction is performed:

in the method, in the process of the invention,

representing an estimate of the last periodic state vector. It should be noted that->

Different forms are selected according to whether the vehicle is traveling straight. />

2) Obtaining a predicted observation vector:

Y _2,k|k-1 ＝H ₂ X _2,k|k-1 (23)

3) Obtaining a predicted covariance matrix:

in the formula (12), the amino acid sequence of the compound,

4) Obtaining Kalman filtering gain:

5) Acquiring a state vector estimated value:

wherein Y is _2,k The observation value of the observation vector at time k.

6) Updating covariance matrix of state vector:

by the extended kalman filtering process described above, an estimate of the state vector can be obtained. Further, the estimated value of the center coordinate of the rear axle of the full trailer can be obtained

And->

Estimated value of course angle/>

Estimated value of driving speed +.>

And an estimated value of the heading angle change rate +.>

In summary, the first driving state at least includes an estimated value of a center coordinate of a rear axle of the trailer, an estimated value of a heading angle, an estimated value of a driving speed, and an estimated value of a change rate of the heading angle.

And 213, determining the observed value of the central coordinate of the front axle of the first section of trailer and the observed value of the course angle according to the estimated value of the central coordinate of the rear axle of the first section of trailer, the estimated value of the course angle, the coordinates and the course angle of the tractor and the kinematic model.

Step 214, determining a second running state of the front axle of the first section of trailer according to the observed value of the central coordinate of the front axle of the first section of trailer, the observed value of the course angle and the kinematic model through an extended Kalman filtering algorithm.

In summary, it is difficult to directly obtain the coordinates of the center of the front axle of the first section of trailer and the course angle thereof due to the limitation of the sensor configuration, and for this problem, in the embodiment of the present disclosure, the estimated value of the center coordinates of the rear axle of the trailer obtained by estimating the traveling state of the rear axle of the full trailer through the extended kalman filter algorithm is calculated according to the above-mentioned

And->

Estimated value of course angle of rear axle of trailer +.>

On the basis, according to the wheelbase of the trailer, the full-scale trailer is combined as shown in figure 5The trailer kinematics model can obtain the observed value of the center coordinates of the front axle of the trailer.

Specifically, the determining, according to the estimated value of the central coordinate of the rear axle of the first section trailer, the estimated value of the course angle, the coordinates and the course angle of the tractor, and the kinematic model of the trailer, the observed value of the central coordinate of the front axle of the first section trailer and the observed value of the course angle includes:

And determining an observed value of the central coordinate of the front shaft of the first section of trailer according to the estimated value of the central coordinate of the rear shaft of the first section of trailer, the estimated value of the course angle and the wheelbase of the first section of trailer.

Optionally, the observed value of the center coordinates of the front axle of the first section of trailer is determined based on the following formula (28):

wherein, (x) ₁ ,y ₁ ) Is the observed value of the central coordinate of the front axle of the first section of trailer,

and->

For the estimated value of the center coordinates of the rear axle of the first section of trailer,/->

Is the estimated value of the heading angle of the rear axle of the first section trailer, l _fr1 Is the wheelbase of the first section of trailer.

Further, determining the coordinates of the junction point according to the coordinates and course angle of the tractor and the distance from the center of the rear axle of the tractor to the junction point, wherein the junction point is a point at the connection position of the tractor and the trailer; determining the observed value of the central heading angle of the front shaft of the first section of trailer according to the observed value of the central coordinate of the front shaft of the trailer, the coordinate of the connecting point, the measured value of the central coordinate of the rear shaft of the first section of trailer, the estimated value of the central heading angle of the rear shaft of the first section of trailer and the kinematic model of the first section of trailer; wherein the wheelbase of the first section of trailer and the distance from the center of the rear axle of the tractor to the coupling point are determined based on a kinematic model of the first section of trailer.

Alternatively, the coordinates of the bond site (i.e., point a in fig. 5) are determined based on the following formula (29):

wherein, (x) _A ，y _A ) Is the coordinate of bond site A, (x) ₀ ，y ₀ ) For the coordinates of the tractor, θ ₀ For the heading angle of the tractor, l _h Is the distance from the center of the rear axle of the tractor to the attachment point a.

In some embodiments, the determining the observed value of the first section trailer front axle center heading angle based on the observed value of the first section trailer front axle center coordinate, the coordinate of the coupling point, the measured value of the first section trailer rear axle center coordinate, the estimated value of the first section trailer rear axle center heading angle, and the kinematic model of the first section trailer includes:

determining a first vector from the center of the rear axle of the first section of trailer to the center of the front axle of the first section of trailer according to the measured value of the center coordinate of the rear axle of the first section of trailer and the observed value of the center coordinate of the front axle of the first section of trailer; determining a second vector from the center of the front axle of the first section of trailer to the connecting point according to the observed value of the center coordinate of the front axle of the first section of trailer and the coordinate of the connecting point; performing cross multiplication operation on the first vector and the second vector to obtain an included angle between the front shaft of the first section of trailer and the rear shaft of the first section of trailer; and determining an observed value of the central heading angle of the front shaft of the first section of trailer according to the included angle between the front shaft of the first section of trailer and the rear shaft of the first section of trailer, the estimated value of the central heading angle of the rear shaft of the first section of trailer and a preset angle relation, wherein the preset angle relation is determined according to a kinematic model of the first section of trailer.

Specifically, the first vector from the center C of the rear axle of the first section of trailer to the center B of the front axle of the first section of trailer may be expressed as

The second vector from the front axle center B of the first section of the trailer to the attachment point A can be expressed as

According to the vector cross relation (shown as the following formula (30)), the included angle +.about.between the front axle of the first section of trailer and the rear axle of the first section of trailer can be obtained>

The observed value of the central course angle of the front axle of the first section of trailer is given by the following formula (31):

wherein θ ₁ Is the observed value of the central course angle of the front axle of the first section of trailer,

for the estimated value of the central course angle of the rear axle of the first section of trailer, +.>

Is the included angle between the front axle of the first section of trailer and the rear axle of the first section of trailer.

Under the condition that the pose of the front axle of the first section of trailer cannot be directly detected, the observed value of the central coordinate of the front axle of the first section of trailer and the observed value of the course angle are obtained.

Further, in order to obtain the estimated value of the center coordinate of the front axle of the first section of trailer and the estimated value of the heading angle, the second running state of the front axle of the first section of trailer may be obtained by estimating the running state of the front axle of the first section of trailer by using an extended kalman filter algorithm based on the observed value of the center coordinate of the front axle of the first section of trailer, the observed value of the heading angle, and the kinematic relationship of the front axle of the first section of trailer as shown in expressions (16) - (18). The process of estimating the running state of the front axle of the first section of trailer through the extended Kalman filtering algorithm is similar to the process of estimating the running state of the rear axle of the first section of trailer through the extended Kalman filtering algorithm.

Specifically, the order state vector is X ₁ ＝[x ₁ y ₁ θ ₁ v ₁ ω ₁ ]The observation vector is: y is Y ₁ ＝[x ₁ y ₁ θ ₁ ]The state equation is shown as the following expression (32), and the observation equation is shown as the following expression (33):

X _1,k ＝f ₁ (X _1,k )+Γ _w1 w _1,k-1 (32)

Y _1,k ＝H ₁ X _1,k +v _1,k (33)

wherein f in expression (32) when the vehicle is traveling straight ₁ (X _1,k ) For the above expression (18), when the vehicle is not traveling straight, f ₁ (X _1,k ) Is the expression (16) above. Γ -shaped structure _w1 ＝I ₅ Representing an identity matrix with dimensions 5 x 5. Observation matrix

w _1,k-1 Representing process noise, v _1,k Representing observed noise. Assuming that the process noise and the observed noise satisfy the gaussian zero mean distribution and are independent of each other, the following relation (34) is:

in which Q ₁ A symmetric covariance matrix representing process noise, R ₁ Representing observed noiseIs a symmetric covariance matrix of (1).

Assume an initial value X of a state vector ₁ (0) Obeying Gaussian distribution, the initial variance matrix is

1) Based on the state equation, state prediction is performed:

in the method, in the process of the invention,

Different forms are selected according to whether the vehicle is traveling straight.

2) Obtaining a predicted observation vector:

Y _1,k|k-1 ＝H ₁ X _1,k|k-1 (36)

3) Obtaining a predicted covariance matrix:

in the formula (29),

4) Obtaining Kalman filtering gain:

5) Acquiring a state vector estimated value:

wherein Y is _1,k The observation value of the observation vector at time k.

6) Updating covariance matrix of state vector:

by the extended Kalman filtering process, the estimated value of the front axle state vector of the first section of trailer can be obtained. Further obtain the estimated value of the center coordinate of the front axle of the first section trailer

And->

Estimated value of course angle +.>

Estimated value of driving speed +.>

And an estimated value of the heading angle change rate +.>

The second driving state includes a pose of the front axle of the first section of trailer, and may specifically be an estimated value of a central heading angle of the front axle of the first section of trailer.

And step 215, determining the pose of other section dragees according to the pose of the front shaft of the first section dragee, the pose of the rear shaft of the first section dragee and the kinematic model.

Specifically, stress analysis is performed according to a kinematic model among the dragees of each section, and the pose of the dragees of other sections is determined according to the pose of the front shaft of the first section of dragee, the pose of the rear shaft of the first section of dragee and the kinematic model.

Fig. 9 is a schematic structural view of a brake device in an embodiment of the present disclosure. As shown in fig. 9: the device comprises: a first determining module 910, configured to determine a pose of each section of trailer towed by the tractor in a driving process according to a kinematic model of motion of the tractor towing the trailer; the second determining module 920 is configured to determine, according to the pose of each section of trailer and the kinematic model, a target maximum deceleration based on a constraint condition of friction force stress balance; a third determining module 930, configured to determine an obstacle closest to the tractor in a driving direction of the tractor according to the planned path of the tractor; a fourth determining module 940 configured to determine a target position at which the tractor uniformly decelerates from the current position to zero relative speed to the obstacle at the target maximum deceleration; a fifth determining module 950 configured to determine an absolute safety position and a desired safety position based on a position of the obstacle, an absolute safety threshold, and a desired safety threshold, where the absolute safety threshold is less than the desired safety threshold; a sixth determination module 960 for determining a target deceleration based on the target position and a relationship between the absolute guard position and the desired guard position; a seventh determination module 970 is configured to control the tractor to perform uniform deceleration braking from the current position at the target deceleration.

Optionally, the second determining module 920 includes: the first determining unit is used for determining second acting force, applied to the rear axle of the current section trailer along the axial direction of the rear axle, and third acting force, applied to the front axle of the current section trailer along the axial direction of the front axle, of the current section trailer according to the first acting force, applied to the current section trailer, of the rear section trailer, the pose of the current section trailer, the pose of the rear section trailer and the kinematic model of the current section trailer; the second determining unit is used for determining a first maximum deceleration according to the second acting force and a second maximum deceleration according to the third acting force based on the constraint condition of the stress balance of the friction force; the third determining unit is used for determining the optional maximum deceleration corresponding to the current section trailer according to the first maximum deceleration and the second maximum deceleration; and the fourth determining unit is used for determining the target maximum deceleration according to the selectable maximum deceleration respectively corresponding to each section of trailer.

Optionally, the first determining unit includes: a first determining subunit, configured to determine the second acting force according to the first acting force, a vehicle body heading of the current section trailer, a front axle heading of the rear section trailer, a wheelbase of the current section trailer, and a trailer hook length of the current section trailer, where the wheelbase of the current section trailer and the length of the current section trailer hook are determined based on the kinematic model, and the current section trailer is coupled to the rear section trailer through the trailer hook; the second determining subunit is used for determining a fourth acting force applied to the current section trailer along the central axis direction according to the first acting force, the vehicle body heading of the current section trailer and the front axle heading of the rear section trailer; and the third determining subunit is used for determining the third acting force applied to the front axle of the current section trailer by the rear axle of the current section trailer and along the axial direction of the front axle according to the fourth acting force, the front axle heading and the rear axle heading of the current section trailer.

Optionally, the second determining unit includes: a fourth determining subunit, configured to determine the first maximum deceleration under a constraint condition that a maximum static friction force along an axial direction of a rear axle of the current section trailer is set to be equal to the second acting force; and a fifth determining subunit, configured to determine the second maximum deceleration under a constraint condition that a maximum static friction force along the axial direction of the front axle of the current section trailer is set to be equal to the third acting force.

Optionally, the third determining unit is specifically configured to determine, as an optional maximum deceleration corresponding to the current section trailer, a smaller one of the first maximum deceleration and the second maximum deceleration;

the fourth determining unit is specifically configured to: and determining the minimum of the selectable maximum decelerations corresponding to the various sections of the tugs as the target maximum deceleration.

Optionally, the fifth determining module 950 includes: a fifth determining unit configured to determine, as the absolute safety position, a position on a planned path between the tractor and the obstacle, at which a distance from the obstacle is the absolute safety threshold; a sixth determination unit that determines, as the desired safe position, a position on a planned path between the tractor and the obstacle, at which a distance from the obstacle is the desired safe threshold.

Optionally, the sixth determining module 960 is specifically configured to determine a third deceleration as the target deceleration if the target position is between the current position and the desired safe position, where the third deceleration is determined based on the current vehicle speed of the tractor, the current position, and the desired safe position; determining the target maximum deceleration as the target deceleration if the target position is between the desired guard position and the absolute guard position; and if the target position exceeds the absolute safe position, determining a first deceleration as the target deceleration, wherein the first deceleration is determined based on the current speed, the current position and the absolute safe position of the tractor. Or if the target position is between the expected safety position and the absolute safety position, updating the expected safety position according to the distance between the target position and the position of the obstacle, and obtaining an updated expected safety position; the target deceleration is determined based on a preset linear constraint relationship, wherein the preset linear constraint relationship is determined based on a current vehicle speed of the tractor, the current position, the absolute safety position, the updated desired safety position, and the target position.

The preset linear constraint relation comprises the following steps:

wherein s2 represents the target position, s3 represents the updated desired safe position, s1 represents the absolute safe position, max_dec represents the target deceleration, s5 represents the current position, ego _vel represents the current vehicle speed of the tractor. The braking device provided in the embodiment of the present disclosure may perform steps in the braking method provided in the embodiment of the present disclosure, and the performing steps and the beneficial effects are not described herein.

Fig. 10 is a schematic structural diagram of an electronic device in an embodiment of the disclosure. Referring now in particular to fig. 10, a schematic diagram of an electronic device 500 suitable for use in implementing embodiments of the present disclosure is shown. The electronic device shown in fig. 10 is merely an example and should not be construed to limit the functionality and scope of use of the disclosed embodiments.

As shown in fig. 10, an electronic device 500 may include a processing means (e.g., a central processor, a graphics processor, etc.) 501 that may perform various suitable actions and processes to implement the methods of embodiments as described in the present disclosure according to a program stored in a Read Only Memory (ROM) 502 or a program loaded from a storage means 508 into a Random Access Memory (RAM) 503. In the RAM 503, various programs and data required for the operation of the electronic apparatus 500 are also stored. The processing device 501, the ROM 502, and the RAM 503 are connected to each other via a bus 504. An input/output (I/O) interface 505 is also connected to bus 504.

In particular, according to embodiments of the present disclosure, the processes described above with reference to flowcharts may be implemented as computer software programs. For example, embodiments of the present disclosure include a computer program product comprising a computer program embodied on a non-transitory computer readable medium, the computer program containing program code for performing the method shown in the flow chart, thereby implementing the braking method as described above. In such an embodiment, the computer program may be downloaded and installed from a network via the communication means 509, or from the storage means 508, or from the ROM 502. The above-described functions defined in the methods of the embodiments of the present disclosure are performed when the computer program is executed by the processing device 501.

It should be noted that the computer readable medium described in the present disclosure may be a computer readable signal medium or a computer readable storage medium, or any combination of the two. The computer readable storage medium can be, for example, but not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or a combination of any of the foregoing. More specific examples of the computer-readable storage medium may include, but are not limited to: an electrical connection having one or more wires, a portable computer diskette, a hard disk, a Random Access Memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disc read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing. In the context of this disclosure, a computer-readable storage medium may be any tangible medium that can contain, or store a program for use by or in connection with an instruction execution system, apparatus, or device. In the present disclosure, however, the computer-readable signal medium may include a data signal propagated in baseband or as part of a carrier wave, with the computer-readable program code embodied therein. Such a propagated data signal may take any of a variety of forms, including, but not limited to, electro-magnetic, optical, or any suitable combination of the foregoing. A computer readable signal medium may also be any computer readable medium that is not a computer readable storage medium and that can communicate, propagate, or transport a program for use by or in connection with an instruction execution system, apparatus, or device. Program code embodied on a computer readable medium may be transmitted using any appropriate medium, including but not limited to: electrical wires, fiber optic cables, RF (radio frequency), and the like, or any suitable combination of the foregoing.

The computer readable medium may be contained in the electronic device; or may exist alone without being incorporated into the electronic device. The computer readable medium carries one or more programs which, when executed by the electronic device, cause the electronic device to perform the braking method.

Alternatively, the electronic device may perform other steps described in the above embodiments when the above one or more programs are executed by the electronic device.

In the context of this disclosure, a machine-readable medium may be a tangible medium that can contain, or store a program for use by or in connection with an instruction execution system, apparatus, or device. The machine-readable medium may be a machine-readable signal medium or a machine-readable storage medium. The machine-readable medium may include, but is not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any suitable combination of the foregoing. More specific examples of a machine-readable storage medium would include an electrical connection based on one or more wires, a portable computer diskette, a hard disk, a Random Access Memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disc read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing.

Scheme 1, a braking method, the method comprising:

Scheme 2, the method according to scheme 1, wherein the determining the target maximum deceleration based on the constraint condition of friction force stress balance according to the pose of each section of trailer and the kinematic model comprises:

For a current section trailer in the section trailers, respectively determining a second acting force applied to a rear shaft of the current section trailer along the axial direction of the rear shaft and a third acting force applied to a front shaft of the current section trailer along the axial direction of the front shaft according to a first acting force applied to the current section trailer by the rear section trailer, the pose of the current section trailer, the pose of the rear section trailer and the kinematic model;

determining a first maximum deceleration according to the second acting force and a second maximum deceleration according to the third acting force based on constraint conditions of friction force stress balance;

determining the optional maximum deceleration corresponding to the current section trailer according to the first maximum deceleration and the second maximum deceleration;

and determining the target maximum deceleration according to the selectable maximum deceleration corresponding to each section of trailer.

The method according to claim 3, wherein the determining, for the current section trailer in the section trailers, the second acting force along the rear axis direction, which is applied to the rear axis of the current section trailer, and the third acting force along the front axis direction, which is applied to the front axis of the current section trailer, according to the first acting force, the pose of the current section trailer, the pose of the rear section trailer, and the kinematic model, which are applied to the current section trailer, respectively, includes:

Determining the second acting force according to the first acting force, the vehicle body heading of the current section trailer, the front axle heading of the rear section trailer, the wheelbase of the current section trailer and the length of a towing hook of the current section trailer, wherein the wheelbase of the current section trailer and the length of the current section towing hook are determined based on the kinematic model, and the current section trailer tows the rear section trailer through the towing hook;

determining a fourth acting force applied to the current section trailer along the central axis direction according to the first acting force, the vehicle body heading of the current section trailer and the front axle heading of the rear section trailer;

and determining the third acting force applied to the front shaft of the current section trailer by the rear shaft of the current section trailer and along the axial direction of the front shaft according to the fourth acting force, the front shaft heading and the rear shaft heading of the current section trailer.

The method according to claim 4, wherein the constraint condition based on the balance of the frictional force and the stress, the determining the first maximum deceleration according to the second acting force, and the determining the second maximum deceleration according to the third acting force, includes:

determining the first maximum deceleration under the constraint condition that the maximum static friction force along the axial direction of the rear shaft of the current section trailer is set to be equal to the second acting force;

And determining the second maximum deceleration under the constraint condition that the maximum static friction force along the axial direction of the front shaft of the current joint trailer is equal to the third acting force.

The method according to claim 5 and claim 2, wherein the determining the optional maximum deceleration corresponding to the current section trailer according to the first maximum deceleration and the second maximum deceleration includes:

determining the smaller of the first maximum deceleration and the second maximum deceleration as the selectable maximum deceleration corresponding to the current section trailer;

the determining the target maximum deceleration according to the selectable maximum deceleration corresponding to each section of trailer respectively comprises the following steps:

Solution 6 the method according to any one of claims 1 to 5, wherein determining the absolute safety position and the desired safety position based on the position of the obstacle, the absolute safety threshold, and the desired safety threshold includes:

Solution 7 the method according to any one of claims 1 to 5, the determining a target deceleration from the relation between the target position and the absolute guard position and the desired guard position, comprising: determining a third deceleration as the target deceleration if the target position is between the current position and the desired safe position, wherein the third deceleration is determined based on a current vehicle speed of the tractor, the current position, and the desired safe position;

determining the target maximum deceleration as the target deceleration if the target position is between the desired guard position and the absolute guard position;

and if the target position exceeds the absolute safe position, determining a first deceleration as the target deceleration, wherein the first deceleration is determined based on the current speed, the current position and the absolute safe position of the tractor.

The method according to any one of claims 1 to 5, the determining a target deceleration from the target position and the relation between the absolute guard position and the desired guard position, comprising:

Scheme 9, the method of scheme 8, the preset linear constraint relationship comprising:

Scheme 10, a braking device, includes:

Scheme 11, an electronic device, the electronic device includes:

one or more processors;

a storage means for storing one or more programs;

the one or more programs, when executed by the one or more processors, cause the one or more processors to implement the methods of any of aspects 1-9.

A solution 12, a computer readable storage medium, having stored thereon a computer program which when executed by a processor implements the method according to any of the solutions 1-9.

The foregoing description is only of the preferred embodiments of the present disclosure and description of the principles of the technology being employed. It will be appreciated by persons skilled in the art that the scope of the disclosure referred to in this disclosure is not limited to the specific combinations of features described above, but also covers other embodiments which may be formed by any combination of features described above or equivalents thereof without departing from the spirit of the disclosure. Such as those described above, are mutually substituted with the technical features having similar functions disclosed in the present disclosure (but not limited thereto).

Claims

1. A method of braking, the method comprising:

controlling the tractor to perform uniform deceleration braking from the current position at the target deceleration;

the determining the target maximum deceleration based on the constraint condition of friction force stress balance according to the pose of each section of trailer and the kinematic model comprises the following steps:

for a current section trailer in each section trailer, respectively determining a second acting force along the axial direction of a rear shaft of the current section trailer and a third acting force along the axial direction of a front shaft of the current section trailer according to a first acting force acted on the current section trailer by the rear section trailer of the current section trailer, a pose of the rear section trailer and the kinematic model, wherein the pose of the current section trailer comprises a vehicle body course of the current section trailer, a front shaft course and a rear shaft course of the current section trailer, the pose of the rear section trailer comprises a front shaft course of the rear section trailer, and the kinematic model is used for determining the wheelbase of the current section trailer and the length of a current section trailer hook;

2. The method according to claim 1, wherein the determining, for the current one of the section drags, the second acting force in the rear axis axial direction to which the rear axis of the current section drags is subjected and the third acting force in the front axis axial direction to which the front axis of the current section drags is subjected according to the first acting force acting on the current section drags by the rear section drags, the pose of the current section drags, the pose of the rear section drags, and the kinematic model, respectively, includes:

determining the second acting force according to the first acting force, the car body heading of the current section trailer, the front shaft heading of the rear section trailer, the wheelbase of the current section trailer and the length of a towing hook of the current section trailer;

3. The method of claim 1, wherein the friction force balance based constraint, determining a first maximum deceleration from the second force, and determining a second maximum deceleration from the third force, comprises:

4. The method of claim 1, wherein the determining the selectable maximum deceleration corresponding to the current joint trailer from the first maximum deceleration and the second maximum deceleration comprises:

5. The method of any of claims 1-4, wherein the determining an absolute safety position and a desired safety position based on the location of the obstacle, an absolute safety threshold, and a desired safety threshold comprises:

6. The method of any one of claims 1-4, wherein said determining a target deceleration from the target position and the relationship between the absolute guard position and the desired guard position comprises: determining a third deceleration as the target deceleration if the target position is between the current position and the desired safe position, wherein the third deceleration is determined based on a current vehicle speed of the tractor, the current position, and the desired safe position;

7. The method of any one of claims 1-4, wherein said determining a target deceleration from the target position and the relationship between the absolute guard position and the desired guard position comprises:

8. The method of claim 7, wherein the predetermined linear constraint relationship comprises:

9. A brake apparatus, comprising:

the second determining module is configured to determine, according to the pose of each section of the trailer and the kinematic model, a target maximum deceleration based on a constraint condition of friction force stress balance, and specifically includes: for a current section trailer in each section trailer, respectively determining a second acting force along the axial direction of a rear shaft of the current section trailer and a third acting force along the axial direction of a front shaft of the current section trailer according to a first acting force acted on the current section trailer by the rear section trailer of the current section trailer, a pose of the rear section trailer and the kinematic model, wherein the pose of the current section trailer comprises a vehicle body course of the current section trailer, a front shaft course and a rear shaft course of the current section trailer, the pose of the rear section trailer comprises a front shaft course of the rear section trailer, and the kinematic model is used for determining the wheelbase of the current section trailer and the length of a current section trailer hook; determining a first maximum deceleration according to the second acting force and a second maximum deceleration according to the third acting force based on constraint conditions of friction force stress balance; determining the optional maximum deceleration corresponding to the current section trailer according to the first maximum deceleration and the second maximum deceleration; determining the target maximum deceleration according to the selectable maximum deceleration corresponding to each section of trailer respectively;

10. An electronic device, the electronic device comprising:

one or more processors;

a storage means for storing one or more programs;

the one or more programs, when executed by the one or more processors, cause the one or more processors to implement the method of any of claims 1-8.

11. A computer readable storage medium, on which a computer program is stored, characterized in that the program, when being executed by a processor, implements the method according to any of claims 1-8.