Braking method, device and equipment of heavy-load truck, medium and vehicle

Abstract

The embodiment of the invention discloses a braking method, device and equipment of a heavy-load truck, a medium and a vehicle, and the method comprises the steps that according to the current motion state of the current heavy-load truck and the distance between the current heavy-load truck and a collision risk object, the expected speed of the current heavy-load truck is estimated; at each moment in the lane changing process, the inner side maximum braking force of inner side wheels of the semitrailer and the outer side maximum braking force of outer side wheels of the semitrailer are determined according to the current motion state and the dynamic model of the current heavy-load truck; according to the magnitude relation among the inner side maximum braking force, the outer side maximum braking force and expected braking force corresponding to the expected speed, the first target braking force of the inner side wheel and the second target braking force of the outer side wheel at the next moment are determined; and the inner side wheels and the outer side wheels are controlled to decelerate at the next moment according to the first target braking force and the second target braking force correspondingly. By the adoption of the technical scheme, the safety of the heavy-duty truck during emergency lane changing can be improved.

Description

Technical Field

[0001] The embodiments of the present invention relate to the field of vehicle control technology, and in particular, to a braking method, device, equipment, medium and vehicle for a heavy-duty truck. Background Art

[0002] At present, a new round of global scientific and technological revolution and industrial transformation with intelligence and networking as important features is booming, and the networking technology of intelligent trucks has been greatly developed. In trunk logistics, a convoy of multiple networked traction semi-trailer trucks is generally formed. When driving on the main roads and highways between cities, the convoy generally has a high driving speed, a large load mass, and a high center of gravity, and often has unstable characteristics when making emergency lane changes. The current mainstream truck lane changing technology is uniform speed lane changing, that is, the speed of each truck in the convoy will not decrease, which will affect the stability of the truck in unconventional conditions, such as emergency lane changing conditions. In emergency conditions, when the truck's driving speed remains unchanged, it is difficult to track the path by only controlling the steering wheel angle, so the truck speed control during emergency lane changing is the key.

[0003] Conventional speed control is to use the maximum braking force on both sides of the wheels to brake together. This does not improve the vehicle's dynamic state, and it is easy to cause safety problems such as wheel slippage or instability during braking. Summary of the invention

[0004] Embodiments of the present invention provide a braking method, device, equipment, medium and vehicle for a heavy-loaded truck, so as to improve the safety and stability of the heavy-loaded truck during emergency lane change.

[0005] In a first aspect, the present invention provides a braking method for a heavy-duty truck, the heavy-duty truck comprising a tractor and a semitrailer connected to the tractor, the method comprising:

[0006] When a collision risk object is detected in front of the lane where the current heavy-loaded truck is located, the expected speed of the current heavy-loaded truck is estimated according to the current motion state of the current heavy-loaded truck and the distance between the current heavy-loaded truck and the collision risk object;

[0007] If the current heavy-loaded truck meets the lane-changing condition, then at each moment in the lane-changing process, according to the current motion state of the current heavy-loaded truck at the current moment and the dynamic model of the current heavy-loaded truck, the maximum inner braking force corresponding to the inner wheel of the semitrailer and the maximum outer braking force corresponding to the outer wheel are determined, wherein the inner wheel is the rear wheel on the semitrailer close to the target lane, and the other rear wheel on the semitrailer except the inner wheel is the outer wheel;

[0008] Determine a first target braking force corresponding to the inner wheel and a second target braking force corresponding to the outer wheel at the next moment according to the magnitude relationship between the inner maximum braking force, the outer maximum braking force and the expected braking force corresponding to the expected speed, wherein the first target braking force is greater than the second target braking force;

[0009] The inner wheel and the outer wheel are controlled to decelerate according to the first target braking force and the second target braking force respectively at the next moment.

[0010] Optionally, determining a first target braking force corresponding to the inner wheel at the next moment and a second target braking force corresponding to the outer wheel according to a magnitude relationship between the inner maximum braking force, the outer maximum braking force and an expected braking force corresponding to an expected speed includes:

[0011] If the maximum inner braking force is greater than the expected braking force corresponding to the expected speed, the expected braking force is used as the first target braking force of the inner wheel at the next moment, and the second target braking force corresponding to the outer wheel at the next moment is set to zero.

[0012] Optionally, determining a first target braking force corresponding to the inner wheel and a second target braking force corresponding to the outer wheel at the next moment according to a magnitude relationship between the inner maximum braking force, the outer maximum braking force and an expected braking force corresponding to an expected speed includes:

[0013] If the maximum inner braking force is less than the expected braking force corresponding to the expected speed, determining whether the sum of the maximum inner braking force and the maximum outer braking force is greater than the expected braking force;

[0014] If the sum is greater than the expected braking force, then determine whether the double value of the maximum inner braking force is greater than the expected braking force;

[0015] If the double value of the maximum inner braking force is greater than the expected braking force, the maximum inner braking force will be used as the first target braking force corresponding to the inner wheel at the next moment, and the difference between the expected braking force and the maximum inner braking force will be used as the second target braking force corresponding to the outer wheel at the next moment.

[0016] Optionally, the method provided by the embodiment of the present invention further includes:

[0017] If the double value of the maximum inner braking force is smaller than the expected braking force, the maximum inner braking force is used as the first target braking force corresponding to the inner wheel and the second target braking force corresponding to the outer wheel at the next moment.

[0018] Optional, current heavy-duty truck dynamics model, including:

[0019] The longitudinal dynamics model of the tractor is used to express the relationship between the product of the mass of the tractor and the longitudinal acceleration and the force acting on the tractor;

[0020] A lateral dynamics model of a tractor, used to represent the relationship between the product of the mass of the tractor and the lateral acceleration and the force acting on the tractor;

[0021] A tractor yaw dynamics model is used to represent the relationship between the product of the moment of inertia of the tractor and the rotational acceleration of the tractor and the sum of the torques of the forces acting on the tractor;

[0022] The semitrailer yaw dynamics model is used to express the relationship between the product of the semitrailer's rotational inertia and the semitrailer's rotational acceleration and the sum of the torques of the forces acting on the tractor;

[0023] A tractor pitch dynamics model is used to represent the relationship between the product of the tractor's rotational inertia and the pitch angular acceleration of the tractor and the sum of the torques of the forces acting on the tractor;

[0024] The pitch dynamics model of the semitrailer is used to express the relationship between the product of the moment of inertia of the semitrailer and the pitch angular acceleration of the semitrailer and the sum of the moments of the forces acting on the semitrailer;

[0025] A tractor roll dynamics model, used to represent the relationship between the product of the tractor's moment of inertia and the roll angular acceleration of the tractor and the torque of the force applied to the tractor;

[0026] The semitrailer roll dynamics model is used to represent the relationship between the product of the rotational inertia of the semitrailer and the roll angular acceleration of the semitrailer and the torque of the force acting on the semitrailer.

[0027] In a second aspect, an embodiment of the present invention further provides a braking device for a heavy-duty truck, the device comprising:

[0028] The expected speed estimation module is configured to estimate the expected speed of the current heavy-loaded truck according to the current motion state of the current heavy-loaded truck and the distance between the current heavy-loaded truck and the collision risk object when a collision risk object is detected in front of the lane where the current heavy-loaded truck is located;

[0029] The maximum wheel braking force determination module is configured to determine, if the current heavy-loaded truck meets the lane-changing condition, at each moment in the lane-changing process, the inner maximum braking force corresponding to the inner wheel of the semitrailer and the outer maximum braking force corresponding to the outer wheel according to the current motion state of the current heavy-loaded truck at the current moment and the dynamic model of the current heavy-loaded truck, wherein the inner wheel is the rear wheel on the semitrailer close to the target lane side, and the other rear wheel on the semitrailer except the inner wheel is the outer wheel;

[0030] a target braking force determination module, configured to determine a first target braking force corresponding to the inner wheel at a next moment and a second target braking force corresponding to the outer wheel according to a magnitude relationship between the inner maximum braking force, the outer maximum braking force and an expected braking force corresponding to an expected speed, wherein the first target braking force is greater than the second target braking force;

[0031] The braking module is configured to control the inner wheel and the outer wheel to decelerate according to the first target braking force and the second target braking force respectively at the next moment.

[0032] Optionally, a target braking force determination module includes:

[0033] The first brake unit is configured to use the expected braking force as the first target braking force of the inner wheel at the next moment if the maximum inner braking force is greater than the expected braking force corresponding to the expected speed, and set the second target braking force corresponding to the outer wheel at the next moment to zero.

[0034] Optionally, the device provided by the embodiment of the present invention further includes:

[0035] a judgment unit configured to judge whether the sum of the maximum inner braking force and the maximum outer braking force is greater than the expected braking force if the maximum inner braking force is less than the expected braking force corresponding to the expected speed; and if the sum is greater than the expected braking force, judge whether the double value of the maximum inner braking force is greater than the expected braking force;

[0036] The second braking unit is configured to use the maximum inner braking force as the first target braking force corresponding to the inner wheel at the next moment if the double value of the maximum inner braking force is greater than the expected braking force, and to use the difference between the expected braking force and the maximum inner braking force as the second target braking force corresponding to the outer wheel at the next moment.

[0037] Optionally, the device provided by the embodiment of the present invention further includes:

[0038] The third braking unit is configured to use the maximum inner braking force as the first target braking force corresponding to the inner wheel and the second target braking force corresponding to the outer wheel at the next moment if the double value of the maximum inner braking force is smaller than the expected braking force.

[0039] Optionally, the dynamic model of the current heavy-duty truck includes:

[0040] The longitudinal dynamics model of the tractor is used to express the relationship between the product of the mass of the tractor and the longitudinal acceleration and the force acting on the tractor;

[0041] A lateral dynamics model of a tractor, used to represent the relationship between the product of the mass of the tractor and the lateral acceleration and the force acting on the tractor;

[0042] A tractor yaw dynamics model is used to represent the relationship between the product of the moment of inertia of the tractor and the rotational acceleration of the tractor and the sum of the torques of the forces acting on the tractor;

[0043] The semitrailer yaw dynamics model is used to express the relationship between the product of the semitrailer's rotational inertia and the semitrailer's rotational acceleration and the sum of the torques of the forces acting on the tractor;

[0044] A tractor pitch dynamics model is used to represent the relationship between the product of the tractor's rotational inertia and the pitch angular acceleration of the tractor and the sum of the torques of the forces acting on the tractor;

[0045] The pitch dynamics model of the semitrailer is used to express the relationship between the product of the moment of inertia of the semitrailer and the pitch angular acceleration of the semitrailer and the sum of the moments of the forces acting on the semitrailer;

[0046] A tractor roll dynamics model, used to represent the relationship between the product of the tractor's moment of inertia and the roll angular acceleration of the tractor and the sum of the torques of the forces acting on the tractor;

[0047] The semitrailer roll dynamics model is used to represent the relationship between the product of the semitrailer's rotational inertia and the roll angular acceleration of the semitrailer and the sum of the torques of the forces acting on the semitrailer.

[0048] In a third aspect, an embodiment of the present invention further provides an electronic device, including:

[0049] A memory storing executable program code;

[0050] a processor coupled to the memory;

[0051] The processor calls the executable program code stored in the memory to execute the braking method for a heavy-load truck provided in any embodiment of the present invention.

[0052] In a fourth aspect, an embodiment of the present invention further provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the braking method for a heavy-loaded truck provided by any embodiment of the present invention.

[0053] In a fifth aspect, an embodiment of the present invention further provides a vehicle, which includes the electronic device provided by an embodiment of the present invention.

[0054] The technical solution provided by the embodiment of the present invention determines the maximum braking force of the inner wheel and the outer wheel of the semitrailer at each moment during the lane change process, and by comparing the magnitude relationship between the inner maximum braking force, the outer maximum braking force and the expected braking force corresponding to the expected speed, the first target braking force corresponding to the inner wheel at the next moment and the second target braking force corresponding to the outer wheel can be obtained. The first target braking force is greater than the second target braking force. This setting can make full use of the inner and outer wheels of the semitrailer for differential braking, reduce the overall speed of the tractor semitrailer truck, and then reduce the load transfer rate and roll angle as well as the lateral force of the semitrailer on the tractor. By adopting the above technical solution, the lateral stability of the tractor is increased, and the safety of the heavy-loaded tractor semitrailer truck during emergency lane change is effectively improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0056] Figure 1a A flowchart of a braking method for a heavy-duty truck provided in Embodiment 1 of the present invention;

[0057] Figure 1b A schematic diagram of a heavy-load start-up provided in Embodiment 1 of the present invention;

[0058] Figure 1c A schematic diagram of an emergency lane-changing condition of a tractor semi-trailer truck provided in Embodiment 1 of the present invention;

[0059] Figure 1d A schematic diagram of a differential braking allocation process provided in Embodiment 1 of the present invention;

[0060] Figure 2 A structural block diagram of a braking device for a heavy-duty truck provided in Embodiment 2 of the present invention;

[0061] Figure 3 A schematic diagram of the structure of an electronic device provided in Embodiment 3 of the present invention. DETAILED DESCRIPTION

[0062] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0063] It should be noted that the terms "including" and "having" and any variations thereof in the embodiments of the present invention and the accompanying drawings are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device including a series of steps or units is not limited to the listed steps or units, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to these processes, methods, products or devices.

[0064] The embodiments of the present invention disclose a braking method, device, equipment, medium and vehicle for a heavy-duty truck, which are described in detail below.

[0065] Embodiment 1

[0066] Figure 1a A flowchart of a braking method for a heavy-load truck provided in Embodiment 1 of the present invention, wherein the heavy-load truck is composed of a tractor and a semi-trailer. Figure 1b This is a schematic diagram of a heavy-load start-up provided in the first embodiment of the present invention. Figure 1b As shown, a part of the body of the semi-trailer q is mounted on the tractor p, and the two are connected by a hinge. The tractor p is provided with a front axle and a rear axle, the front axle is installed with a front wheel, and the rear axle is installed with a rear wheel. The semi-trailer q is provided with a semi-trailer axle, and the semi-trailer axle is installed with wheels, wherein the wheels on the same side of the steering direction are the inner wheels, and the wheels on the other side are the outer wheels. The method provided in this embodiment is a method for differential braking based on the braking force of the inner and outer wheels of the semi-trailer. The method can be applied to vehicle-mounted terminals such as vehicle-mounted ECU (Electronic Control Unit), and can also be applied to servers, which is not limited by the embodiment of the present invention. The application scenario of the method provided in this embodiment can be a scenario of emergency lane change when a heavy-loaded truck encounters an obstacle. The method provided in this embodiment can be executed by a braking device of a heavy-loaded truck, and the device can be implemented by software and / or hardware. As Figure 1a As shown, the method provided in this embodiment specifically includes:

[0067] S110. When a collision risk object is detected in front of the lane where the current heavy-loaded truck is located, an expected speed of the current heavy-loaded truck is estimated according to the current motion state of the current heavy-loaded truck and the distance between the current heavy-loaded truck and the collision risk object.

[0068] The collision risk object may be a pedestrian, a vehicle or other obstacles prone to collision. The collision risk object may be detected by a vehicle-mounted radar, such as a laser radar, a millimeter-wave radar or a visual sensor such as a vehicle-mounted camera. The data collected by the vehicle-mounted sensor may be used to determine the distance between the current heavy-load truck and the collision risk object.

[0069] In this embodiment, the expected speed of the current heavy-load truck is the target speed after braking, that is, when the vehicle is driven at the target speed after braking, the current heavy-load truck can change lanes normally and will not collide with obstacles. For example, if the current speed is 100 km / h and the distance to the obstacle is 1 km, in order to avoid collision with the obstacle, the vehicle reaches the target speed of 20 km / h before the distance to the obstacle is 0.3 km after deceleration braking.

[0070] In this embodiment, the expected speed can be obtained based on the current motion state of the heavy-loaded truck and the distance between the heavy-loaded truck and the collision risk object. The motion state of the vehicle includes speed, acceleration, yaw angle, etc. The expected braking force of the vehicle can be obtained based on the expected speed and combined with factors such as the current motion state of the vehicle, the distance between the current vehicle and the risk collision object, and the friction of the road surface. The faster the vehicle speed, the greater the expected braking force, and the closer the obstacle distance, the greater the expected braking force.

[0071] S120. If the current heavy-loaded truck meets the lane-changing conditions, then at each moment in the lane-changing process, the maximum inner braking force corresponding to the inner wheels of the semitrailer and the maximum outer braking force corresponding to the outer wheels are determined according to the current motion state of the current heavy-loaded truck at the current moment and the dynamic model of the current heavy-loaded truck.

[0072] It is understood by those skilled in the art that the braking of a heavy-duty truck is mainly achieved by braking the semitrailer to drive the tractor to brake. The front wheels of the semitrailer are mounted on the tractor, and the braking of the semitrailer is mainly achieved by the rear wheels. For example, Figure 1c This is a schematic diagram of an emergency lane change condition of a tractor semi-trailer truck provided in Embodiment 1 of the present invention. Figure 1c As shown, the front axle (A1 axle) of the tractor p is provided with two sets of front wheels of the tractor, and the rear axle (A2 axle) of the tractor p is provided with two sets of rear wheels of the tractor. The semitrailer q is mounted on the tractor p, and the axle (A4 axle) of the semitrailer q is provided with two sets of wheels of the semitrailer. In this embodiment, the wheels on the semitrailer close to the target lane are the inner wheels, and the wheels on the semitrailer other than the inner wheels are the outer wheels, for example Figure 1c When the semi-trailer encounters an obstacle and changes lanes to the left, the left wheel of the semi-trailer is the inner wheel, and its braking force is the inner braking force F. in The right wheel is the outer wheel, and its braking force is the outer braking force F out If the lane is changed to the right, the right wheel of the semi-trailer is the inner wheel and the left wheel is the outer wheel. When the braking force of the inner wheel is greater than the braking force of the outer wheel, an additional yaw force F TSince the additional yaw force is in the opposite direction to the lateral force of the semitrailer on the tractor, the lateral force of the semitrailer on the tractor can be reduced.

[0073] In this embodiment, when the distance between the front obstacle and the towing semi-trailer truck is relatively close, it is regarded as an emergency condition. In such an emergency condition, the dynamic state of the towing semi-trailer truck is greatly different, which will cause the vertical force and braking force of the inner wheel to decrease, and the vertical force and braking force of the outer wheel to increase. Therefore, it is necessary to calculate the maximum braking force of the inner and outer wheels. The maximum braking force is the boundary of the inner and outer wheel braking force in the differential braking distribution mechanism, which is of great significance for the judgment of the wheel differential braking mechanism.

[0074] Combine the following Figure 1c First, the establishment of a simplified dynamic model of a three-axle heavy-duty tractor semi-trailer, which is mainly composed of the front axle (A1 axle) of the tractor p, the rear axle (A2 axle) of the tractor p, and the axle (A4 axle) where the wheels of the semi-trailer q are located, is introduced:

[0075] Firstly, a planar coupled dynamics model is established.

[0076] The tractor p and the semitrailer q are connected together by an articulated plate to form a vehicle combination. The tractor mainly provides direction and power, and the semitrailer is in a passive following state, coupled by the articulated force of the articulated plate. The longitudinal component of the articulated force is defined as F xh , the negative direction along the tractor is positive; the lateral component of the articulation force is F yh , which is positive along the right side of the tractor. The opposite reaction force is also F xh 、F yh , acting on the semi-trailer.

[0077] The yaw angle of the tractor is defined as The yaw angle of the semitrailer is Therefore, the relative articulation angle between the tractor and the semi-trailer is defined as θ, that is:

[0078]

[0079] The hinge point of the tractor and the semi-trailer is h, and the longitudinal velocity of the hinge point is defined as u h , the lateral velocity is v h , according to the same instantaneous center principle, that is:

[0080] u h =u p

[0081] v h =v p -ω p l c

[0082] where u p is the longitudinal velocity of the tractor, v p is the lateral speed of the tractor, ω p is the yaw angular velocity of the tractor, l c is the distance from the center of mass of the tractor to the hinge point h.

[0083] Through the transverse and longitudinal velocities of the hinge point h and the principle of the same instantaneous center, the longitudinal velocity u of the center of mass of the semitrailer can be calculated by inserting it into the semitrailer q q , lateral velocity v q ,Right now:

[0084]

[0085] u q =u h cosθ-v h sinθ

[0086] v q =u h sinθ+v h cosθ-ω q l d

[0087] For the above formula about the articulation angle θ, the longitudinal speed u q and the lateral velocity v q The derivative can calculate the longitudinal acceleration of the semitrailer and lateral acceleration And it lays the foundation for solving the horizontal and vertical forces at the hinge point h, that is:

[0088]

[0089] According to the semi-trailer q in x h O q y h The forces in the x and y directions of the coordinate system are balanced, and the longitudinal force F at the hinge can be obtained. xh and the lateral force F yh ,Right now:

[0090]

[0091] Among them, M q represents the total mass of the semi-trailer q; ω q is the yaw rate of the semitrailer, F x4l F represents the longitudinal force of the wheel on the left side of the semitrailer in the direction of travel (hereinafter referred to as the 4l wheel), x4r F represents the longitudinal force of the wheel on the right side of the semitrailer in the direction of travel (hereinafter referred to as 4r wheel); y4l、F y4r They represent the lateral force of the semitrailer's 41st wheel and 4r wheel respectively. T It indicates the additional yaw force in the y direction of the semitrailer caused by differential braking, which is formed by the torque difference between the outer wheel and the inner wheel.

[0092] Specifically, when the truck changes lanes to the left of the driving direction, the additional yaw force expression is:

[0093] F T =0.5d q (F x4r -F x4l ) / l d

[0094] When the truck changes lanes to the right of the driving direction, the additional yaw force is expressed as:

[0095] F T =0.5d q (F x4l -F x4r ) / l d

[0096] Therefore, the planar 4-DOF coupled dynamic model of the tractor semi-trailer truck is established according to its dynamic model, namely:

[0097] (1) Longitudinal dynamics model of tractor p

[0098] This model is used to express the relationship between the product of the mass of the tractor and the longitudinal acceleration and the force exerted on the tractor. The specific formula is as follows:

[0099]

[0100] (2) Tractor p lateral dynamics model

[0101] This model is used to express the relationship between the product of the mass of the tractor and the lateral acceleration and the force exerted on the tractor. The specific formula is as follows:

[0102]

[0103] (3) Tractor yaw dynamics model

[0104] This model is used to express the relationship between the product of the moment of inertia of the tractor and the rotational acceleration of the tractor and the sum of the torques of the forces acting on the tractor. The specific formula is as follows:

[0105]

[0106] (4) Semitrailer yaw dynamics model

[0107] This model is used to express the relationship between the product of the moment of inertia of the semitrailer and the rotational acceleration of the semitrailer and the sum of the torques of the forces acting on the tractor. The specific formula is as follows:

[0108]

[0109] In the above formula, M p is the total mass of the tractor p; I zp ,I zq They represent the moment of inertia of the tractor and the semitrailer around the z-axis respectively; δ 1l represents the steering angle of the left front wheel (hereinafter referred to as the 11th wheel) of the tractor based on the driving direction, δ 1r Indicates the steering angle of the right front wheel (hereinafter referred to as 1r wheel) of the tractor based on the driving direction; F x1l 、F x1r They represent the longitudinal force of wheel 11 and wheel 1r respectively, and F x2l F represents the longitudinal force of the left rear wheel (hereinafter referred to as the 21st wheel) of the tractor based on the driving direction, x2r F represents the longitudinal force of the right rear wheel (hereinafter referred to as 2r wheel) of the tractor based on the driving direction; y1l 、F y1r 、F y2l 、F y2r They represent the lateral force of wheel 11, wheel 1r, wheel 21, and wheel 2r respectively; d p d q Respectively represent the wheel center distance of the tractor and the wheel center distance of the semi-trailer; l a , l b They represent the distance from the center of mass of the tractor to the A1 axis and the distance from the center of mass of the tractor to the A2 axis respectively; l d , l e They respectively represent the distance from the center of mass of the semitrailer to the articulation point h and the distance from the center of mass of the semitrailer to the A4 axis.

[0110] Secondly, establish the pitch and roll dynamics model

[0111] Due to the heavy load, high center of mass and slow dynamic response of tractor semi-trailer trucks, the vehicle body will pitch and roll when changing lanes at high speed. The body posture will change significantly, which will cause the load transfer of the vehicle body and the lateral and longitudinal forces of the wheels to change significantly, which will have a negative impact on the safety of emergency lane changes of trucks. First, the reasons for the pitch and roll motion of tractor semi-trailer trucks are explored. Since the tractor semi-trailer trucks use differential braking during high-speed emergency lane changes, a longitudinal virtual inertia force will be generated. Combined with the gravity component, the center of mass of the vehicle body will rotate around the longitudinal rotation center O. At this time, the suspension of the front and rear axles is compressed or stretched to provide a pair of reaction forces to resist the rotation of the vehicle body, forming the pitch motion of the vehicle body. Similarly, the roll motion is similar. Since the truck will have a strong lateral motion when changing lanes at high speed, a lateral virtual inertia force will be generated. Considering the influence of the gravity component, the center of mass of the vehicle body will rotate around the lateral rotation center O. At this time, the suspension inside and outside the vehicle body is stretched or compressed to generate a pair of reaction forces to resist the rotational movement of the vehicle body, thereby forming the roll movement of the vehicle body.

[0112] Therefore, a 4-DOF dynamic model of the pitching and rolling motion of the tractor semi-trailer truck is established, and its expression is as follows:

[0113] (1) Pitch dynamics model of tractor

[0114] This model is used to express the relationship between the product of the moment of inertia of the tractor and the pitch angular acceleration of the tractor and the sum of the torques of the forces acting on the tractor. The specific formula is as follows:

[0115]

[0116] (2) Pitch dynamics model of semitrailer

[0117] This model is used to express the relationship between the product of the moment of inertia of the semitrailer and the pitch angular acceleration of the semitrailer and the sum of the torque of the force acting on the semitrailer. The specific formula is as follows:

[0118]

[0119] (3) Tractor roll dynamics model

[0120] This model is used to express the relationship between the product of the moment of inertia of the tractor and the roll angular acceleration of the tractor and the sum of the torques of the forces acting on the tractor. The specific formula is as follows:

[0121]

[0122] (4) Semitrailer roll dynamics model

[0123] This model is used to express the relationship between the product of the moment of inertia of the semitrailer and the roll angular acceleration of the semitrailer and the sum of the torque of the force acting on the semitrailer. The specific formula is as follows:

[0124]

[0125] In the above formula, α p , α q They represent the pitch angle of the tractor p and the pitch angle of the semitrailer q respectively. They represent the pitch angular velocity of the tractor p and the pitch angular velocity of the semitrailer q respectively, They represent the pitching acceleration of the tractor p and the pitching acceleration of the semitrailer q respectively; β p , β q They represent the roll angle of the tractor p and the roll angle of the semitrailer q respectively. They represent the roll angular velocity of the tractor p and the roll angular velocity of the semitrailer q respectively, I represents the roll angle acceleration of the tractor p and the roll angle acceleration of the semitrailer q respectively; xp ,I xq They represent the moment of inertia of the tractor p and the semitrailer q around the x-axis, respectively. yp ,I yq They represent the moment of inertia of the tractor p and the semitrailer q around the y-axis respectively; h p 、h q They represent the center of mass height of the tractor p and the center of mass height of the semitrailer q, respectively. pe 、h qe They represent the rotation center height of the tractor p and the rotation center height of the semi-trailer q respectively; g represents the acceleration due to gravity.

[0126] The above pitch and roll dynamics model can be used to calculate the suspension force at each wheel of the tractor semi-trailer truck, and then solve the dynamic change of each wheel load of the truck during the emergency lane change process.

[0127] In addition, the spring damping system is represented by an equivalent spring stiffness K i and the damping coefficient C i represents (i=1, 2, 4). qp It represents the torque transmitted between the semi-trailer q and the tractor p, and is calculated according to the piecewise function corresponding to the roll angle difference between the two vehicle bodies (converted from radians to degrees).

[0128] K ql =K qr =K4

[0129] C ql =C qr =C4

[0130] K pl =K pr =K1+K2

[0131] C pl =C pr =C1+C2

[0132]

[0133] Among them, K pl , K ql They represent the left spring stiffness of the tractor p and the left spring stiffness of the semitrailer q, respectively. pr , K qr They represent the right spring stiffness of the tractor p and the right spring stiffness of the semitrailer q respectively; C pl , C ql They represent the left damping coefficient of the tractor p and the left damping coefficient of the semitrailer q, respectively. pr , C qr They represent the right damping coefficient of the tractor p and the right damping coefficient of the semi-trailer q respectively; k=1000.

[0134] Define the truck longitudinal suspension force matrix as F kc_α The lateral suspension force matrix of the truck is F kc_β ,Right now:

[0135]

[0136] Define the force matrix on the suspension at each wheel as F kc_lr , which is expressed as follows:

[0137] F kc_lr =[F kc_1l F kc_1r F kc_2l F kc_2r F kc_4l F kc_4r ] T

[0138] F kc_lr =F kc_α +F kc_β

[0139] After obtaining the suspension force at each wheel, it is also necessary to vertically distribute the vertical force at the hinge of the semi-trailer truck q to the tractor p through the capstan, so that each wheel of the tractor can well bear the vertical load from the trailer q. For the vertical load at the hinge, this paper uses the characteristics of the KC suspension for analogy calculation, and simplifies this place into a "KC suspension", defining the suspension force F at this place kch :

[0140]

[0141] In order to better distribute the vertical load of each wheel, the distribution matrix at the hinge is defined as A h , this matrix is ​​designed to distribute the vertical force at the hinge to the front and rear axle wheels in equal proportions, and its expression is as follows:

[0142]

[0143] Define the truck static gravity distribution matrix as G m , whose expression is:

[0144]

[0145] G m =[G m1 G m2 ] T

[0146] Therefore, the static tire vertical force can be expressed as F z0 , the dynamic tire vertical force can be expressed as F z , which is expressed as follows:

[0147]

[0148] Wheel static vertical force F z0 and dynamic vertical force F z It is the key parameter for solving the tire model and is also an important basis for studying the stability of high-speed emergency lane change of tractor semi-trailer trucks. z The vertical force F of the rear wheel of the semitrailer is extracted from the matrix z4l and F z4r , when turning to the left F z4l is the vertical force of the inner wheel, F z4r is the vertical force of the outer wheel, μ is the road friction coefficient. At this time, the maximum inner braking force F corresponding to the inner wheel is calculated. in-max , the maximum outer braking force F corresponding to the outer wheel out-max They are:

[0149] F in-max =μF z4l

[0150] F out-max =μF z4r

[0151] In order to obtain the maximum braking force F of the inner and outer wheels in-max 、F out-max Then, the maximum braking force is used as the judgment condition of the differential braking distribution mechanism and compared with the expected braking force Fdes For comparison, please refer to step S130 for details.

[0152] S130, determining a first target braking force corresponding to the inner wheel and a second target braking force corresponding to the outer wheel at the next moment according to a magnitude relationship among the inner maximum braking force, the outer maximum braking force and the expected braking force corresponding to the expected speed.

[0153] Preferably, the first target braking force is greater than the second target braking force. This arrangement can decelerate the semi-trailer by differential braking of the inner and outer wheels, and generate a yaw force. The yaw force can effectively reduce the lateral force of the semi-trailer on the tractor, thereby effectively reducing the lateral force of the semi-trailer on the tractor, avoiding the problem of wheel braking slip during lane changing, and improving the stability and safety of heavy-loaded trucks during lane changing.

[0154] Figure 1d A schematic diagram of a differential braking allocation process according to the first embodiment of the present invention is shown in FIG. Figure 1d As shown, step S130 specifically includes:

[0155] S131. Determine whether the maximum inner braking force is greater than the expected braking force corresponding to the expected speed. If so, execute step S132; otherwise, execute step S133.

[0156] S132: The expected braking force is used as the first target braking force of the inner wheel at the next moment, and the second target braking force corresponding to the outer wheel at the next moment is set to zero.

[0157] S133, determine whether the sum of the maximum inner braking force and the maximum outer braking force is greater than the expected braking force, if so, execute step S134; otherwise, execute step S137,

[0158] S134, determine whether the double value of the maximum inner braking force is greater than the expected braking force, if so, execute step S135, otherwise, execute step S136.

[0159] S135, taking the maximum inner braking force as the first target braking force corresponding to the inner wheel at the next moment, and taking the difference between the expected braking force and the maximum inner braking force as the second target braking force corresponding to the outer wheel at the next moment.

[0160] S136: The maximum inner braking force is used as the first target braking force corresponding to the inner wheel and the second target braking force corresponding to the outer wheel at the next moment.

[0161] Optionally, when the double value of the maximum inner braking force is less than the expected braking force, the braking method can also be: using the maximum inner braking force as the first target braking force corresponding to the inner wheel at the next moment, and using the maximum outer braking force as the second target braking force corresponding to the outer wheel at the next moment.

[0162] S137, using the maximum inner braking force as the first target braking force corresponding to the inner wheel at the next moment, and using the maximum outer braking force as the second target braking force corresponding to the outer wheel at the next moment.

[0163] By applying the above-mentioned inner and outer wheel braking force distribution mechanism for braking, the overall speed of the towing semi-trailer truck can be reduced, thereby reducing the load transfer rate and the roll angle.

[0164] S140, controlling the inner wheel and the outer wheel to decelerate according to the first target braking force and the second target braking force respectively at the next moment.

[0165] In this embodiment, a braking command may be sent to the brake pedal at the current moment to control the inner wheel and the outer wheel to decelerate according to the first target braking force and the second target braking force respectively at the next moment.

[0166] In this embodiment, at each moment in the lane changing process, by determining the maximum braking force of the inner wheel and the outer wheel of the semitrailer, and by comparing the magnitude relationship between the inner maximum braking force, the outer maximum braking force and the expected braking force, the first target braking force corresponding to the inner wheel at the next moment and the second target braking force corresponding to the outer wheel can be obtained. The first target braking force is greater than the second target braking force. In this way, the inner and outer wheels of the semitrailer can be fully utilized for differential braking, reducing the overall speed of the tractor semitrailer truck, thereby reducing the load transfer rate and the roll angle as well as the lateral force of the semitrailer on the tractor. By adopting the above technical solution, the lateral stability of the tractor is increased, and the safety of the heavy-load tractor semitrailer truck during emergency lane change is effectively improved.

[0167] Embodiment 2

[0168] Figure 2 A structural block diagram of a braking device for a heavy-duty truck provided in Embodiment 2 of the present invention, such as Figure 2 As shown, the device includes: an expected speed estimation module 210, a wheel maximum braking force determination module 220, a target braking force determination module 230 and a braking module 240, wherein:

[0169] The expected speed estimation module 210 is configured to estimate the expected speed of the current heavy-load truck according to the current motion state of the current heavy-load truck and the distance between the current heavy-load truck and the collision risk object when a collision risk object is detected in front of the lane where the current heavy-load truck is located;

[0170] The wheel maximum braking force determination module 220 is configured to determine the inner maximum braking force corresponding to the inner wheel of the semitrailer and the outer maximum braking force of the outer wheel at each moment in the lane changing process if the current heavy-loaded truck meets the lane changing condition, according to the current motion state of the current heavy-loaded truck at the current moment and the dynamic model of the current heavy-loaded truck, wherein the inner wheel is the rear wheel on the semitrailer close to the target lane side, and the other rear wheel on the semitrailer except the inner wheel is the outer wheel;

[0171] a target braking force determination module 230, configured to determine a first target braking force corresponding to the inner wheel and a second target braking force corresponding to the outer wheel at a next moment according to a magnitude relationship between the inner maximum braking force, the outer maximum braking force and the expected braking force corresponding to the expected speed, wherein the first target braking force is greater than the second target braking force;

[0172] The braking module 240 is configured to control the inner wheel and the outer wheel to decelerate according to the first target braking force and the second target braking force respectively at the next moment.

[0173] Optionally, the target braking force determination module 230 includes:

[0174] The first braking unit is configured to use the expected braking force as the first target braking force of the inner wheel at the next moment if the maximum inner braking force is greater than the expected braking force corresponding to the expected speed, and set the second target braking force corresponding to the outer wheel at the next moment to zero.

[0175] Optionally, the device provided by the embodiment of the present invention further includes:

[0176] a judgment unit configured to judge whether the sum of the maximum inner braking force and the maximum outer braking force is greater than the expected braking force if the maximum inner braking force is less than the expected braking force corresponding to the expected speed; and if the sum is greater than the expected braking force, judge whether the double value of the maximum inner braking force is greater than the expected braking force;

[0177] The second braking unit is configured to use the maximum inner braking force as the first target braking force corresponding to the inner wheel at the next moment if the double value of the maximum inner braking force is greater than the expected braking force, and to use the difference between the expected braking force and the maximum inner braking force as the second target braking force corresponding to the outer wheel at the next moment.

[0178] Optionally, the device provided by the embodiment of the present invention further includes:

[0179] The third braking unit is configured to use the maximum inner braking force as the first target braking force corresponding to the inner wheel and the second target braking force corresponding to the outer wheel at the next moment if the double value of the maximum inner braking force is smaller than the expected braking force.

[0180] Optionally, the dynamic model of the current heavy-duty truck includes:

[0181] The longitudinal dynamics model of the tractor is used to express the relationship between the product of the mass of the tractor and the longitudinal acceleration and the force acting on the tractor;

[0182] A lateral dynamics model of a tractor, used to represent the relationship between the product of the mass of the tractor and the lateral acceleration and the force acting on the tractor;

[0183] A tractor yaw dynamics model is used to represent the relationship between the product of the moment of inertia of the tractor and the rotational acceleration of the tractor and the sum of the torques of the forces acting on the tractor;

[0184] The semitrailer yaw dynamics model is used to express the relationship between the product of the semitrailer's rotational inertia and the semitrailer's rotational acceleration and the sum of the torques of the forces acting on the tractor;

[0185] A tractor pitch dynamics model is used to represent the relationship between the product of the tractor's rotational inertia and the pitch angular acceleration of the tractor and the sum of the torques of the forces acting on the tractor;

[0186] The pitch dynamics model of the semitrailer is used to express the relationship between the product of the moment of inertia of the semitrailer and the pitch angular acceleration of the semitrailer and the sum of the moments of the forces acting on the semitrailer;

[0187] A tractor roll dynamics model, used to represent the relationship between the product of the tractor's moment of inertia and the roll angular acceleration of the tractor and the sum of the torques of the forces acting on the tractor;

[0188] The semitrailer roll dynamics model is used to represent the relationship between the product of the semitrailer's rotational inertia and the roll angular acceleration of the semitrailer and the sum of the torques of the forces acting on the semitrailer.

[0189] Embodiment 3

[0190] See also Figure 3 , Figure 3 A schematic diagram of the structure of an electronic device provided in Embodiment 3 of the present invention.

[0191] like Figure 3 As shown, the electronic device may include:

[0192] A memory 701 storing executable program codes;

[0193] a processor 702 coupled to the memory 701;

[0194] The processor 702 calls the executable program code stored in the memory 701 to execute the braking method for a heavy-loaded truck provided in any embodiment of the present invention.

[0195] An embodiment of the present invention discloses a computer-readable storage medium storing a computer program, wherein the computer program enables a computer to execute the braking method for a heavy-load truck provided by any embodiment of the present invention.

[0196] An embodiment of the present invention further provides a vehicle, which includes the electronic device provided by an embodiment of the present invention or the braking device of a heavy-duty truck provided by any embodiment of the present invention.

[0197] In various embodiments of the present invention, it should be understood that the size of the serial numbers of the above-mentioned processes does not mean the necessary order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present invention.

[0198] In the embodiments provided by the present invention, it should be understood that "B corresponding to A" means that B is associated with A, and B can be determined according to A. However, it should also be understood that determining B according to A does not mean determining B only according to A, and B can also be determined according to A and / or other information.

[0199] In addition, each functional unit in each embodiment of the present invention may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit. The above-mentioned integrated unit may be implemented in the form of hardware or in the form of software functional units.

[0200] If the above integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-accessible memory. Based on this understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product, which is stored in a memory and includes several requests for a computer device (which can be a personal computer, a server or a network device, etc., specifically a processor in a computer device) to perform some or all of the steps of the above methods of various embodiments of the present invention.

[0201] Those skilled in the art can understand that all or part of the steps in the various methods of the above embodiments can be completed by instructing related hardware through a program, and the program can be stored in a computer-readable storage medium, and the storage medium includes a read-only memory (ROM), a random access memory (RAM), a programmable read-only memory (PROM), an erasable programmable read-only memory (EPROM), a one-time programmable read-only memory (OTPROM), an electronically erasable rewritable read-only memory (EEPROM), a compact disc (CD-ROM) or other optical disc storage, magnetic disk storage, magnetic tape storage, or any other computer-readable medium that can be used to carry or store data.

[0202] Those skilled in the art can understand that the accompanying drawings are only schematic diagrams of an embodiment, and the modules or processes in the accompanying drawings are not necessarily required to implement the present invention.

[0203] Those skilled in the art can understand that the modules in the device in the embodiment can be distributed in the device in the embodiment according to the description of the embodiment, or can be changed accordingly and located in one or more devices different from the embodiment. The modules in the above embodiment can be combined into one module, or can be further divided into multiple sub-modules.

[0204] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A braking method for a heavy-load truck, the heavy-load truck comprising a tractor and a semitrailer connected to the tractor, characterized in that: include: When a collision risk object is detected in front of the lane where the current heavy-loaded truck is located, estimating the expected speed of the current heavy-loaded truck according to the current motion state of the current heavy-loaded truck and the distance between the current heavy-loaded truck and the collision risk object; If the current heavy-loaded truck meets the lane-changing condition, then at each moment in the lane-changing process, according to the current motion state of the current heavy-loaded truck at the current moment and the dynamic model of the current heavy-loaded truck, the maximum inner braking force corresponding to the inner wheel of the semi-trailer and the maximum outer braking force corresponding to the outer wheel are determined, wherein the inner wheel is the wheel on the semi-trailer close to the target lane, and the other wheel on the semi-trailer except the inner wheel is the outer wheel; Determine a first target braking force corresponding to the inner wheel and a second target braking force corresponding to the outer wheel at the next moment according to the magnitude relationship between the inner maximum braking force, the outer maximum braking force and the expected braking force corresponding to the expected speed, wherein the first target braking force is greater than the second target braking force; The inner wheel and the outer wheel are controlled to decelerate according to the first target braking force and the second target braking force respectively at the next moment.

2. The method according to claim 1, characterized in that The determining, according to the magnitude relationship between the inner maximum braking force, the outer maximum braking force and the expected braking force corresponding to the expected speed, a first target braking force corresponding to the inner wheel and a second target braking force corresponding to the outer wheel at a next moment, comprises: If the maximum inner braking force is greater than the expected braking force corresponding to the expected speed, the expected braking force is used as the first target braking force of the inner wheel at the next moment, and the second target braking force corresponding to the outer wheel at the next moment is set to zero.

3. The method according to claim 1, characterized in that The determining, according to the magnitude relationship between the inner maximum braking force, the outer maximum braking force and the expected braking force corresponding to the expected speed, a first target braking force corresponding to the inner wheel and a second target braking force corresponding to the outer wheel at a next moment, comprises: If the inner maximum braking force is less than the expected braking force corresponding to the expected speed, determining whether the sum of the inner maximum braking force and the outer maximum braking force is greater than the expected braking force; If the sum is greater than the expected braking force, determining whether the double value of the inner maximum braking force is greater than the expected braking force; If the double value of the inner maximum braking force is greater than the expected braking force, the inner maximum braking force will be used as the first target braking force corresponding to the inner wheel at the next moment, and the difference between the expected braking force and the inner maximum braking force will be used as the second target braking force corresponding to the outer wheel at the next moment.

4. The method according to claim 3, characterized in that The method further comprises: If the double value of the inner maximum braking force is smaller than the expected braking force, the inner maximum braking force is used as the first target braking force corresponding to the inner wheel and the second target braking force corresponding to the outer wheel at the next moment.

5. The method according to any one of claims 1 to 4, characterized in that: The dynamic model of the current heavy-duty truck includes: The longitudinal dynamics model of the tractor is used to express the relationship between the product of the mass of the tractor and the longitudinal acceleration and the force acting on the tractor; A lateral dynamics model of a tractor, used to represent the relationship between the product of the mass of the tractor and the lateral acceleration and the force acting on the tractor; A tractor yaw dynamics model is used to represent the relationship between the product of the moment of inertia of the tractor and the rotational acceleration of the tractor and the sum of the torques of the forces acting on the tractor; The semitrailer yaw dynamics model is used to express the relationship between the product of the semitrailer's rotational inertia and the semitrailer's rotational acceleration and the sum of the torques of the forces acting on the tractor; A tractor pitch dynamics model is used to represent the relationship between the product of the tractor's rotational inertia and the pitch angular acceleration of the tractor and the sum of the torques of the forces acting on the tractor; The pitch dynamics model of the semitrailer is used to express the relationship between the product of the moment of inertia of the semitrailer and the pitch angular acceleration of the semitrailer and the sum of the moments of the forces acting on the semitrailer; A tractor roll dynamics model, used to represent the relationship between the product of the tractor's moment of inertia and the roll angular acceleration of the tractor and the sum of the torques of the forces acting on the tractor; The semitrailer roll dynamics model is used to represent the relationship between the product of the semitrailer's rotational inertia and the roll angular acceleration of the semitrailer and the sum of the torques of the forces acting on the semitrailer.

6. A braking device for a heavy-duty truck, characterized in that: include: The expected speed estimation module is configured to estimate the expected speed of the current heavy-loaded truck according to the current motion state of the current heavy-loaded truck and the distance between the current heavy-loaded truck and the collision risk object when a collision risk object is detected in front of the lane where the current heavy-loaded truck is located; The maximum wheel braking force determination module is configured to determine, if the current heavy-loaded truck meets the lane-changing condition, at each moment in the lane-changing process, the inner maximum braking force corresponding to the inner wheel of the semitrailer and the outer maximum braking force corresponding to the outer wheel according to the current motion state of the current heavy-loaded truck at the current moment and the dynamic model of the current heavy-loaded truck, wherein the inner wheel is the wheel on the semitrailer close to the target lane side, and the other side wheel of the semitrailer except the inner wheel is the outer wheel; a target braking force determination module, configured to determine a first target braking force corresponding to the inner wheel and a second target braking force corresponding to the outer wheel at a next moment according to a magnitude relationship between the inner maximum braking force, the outer maximum braking force and an expected braking force corresponding to the expected speed, wherein the first target braking force is greater than the second target braking force; The braking module is configured to control the inner wheel and the outer wheel to decelerate according to the first target braking force and the second target braking force respectively at the next moment.

7. The device according to claim 6, characterized in that The target braking force determination module comprises: The first braking unit is configured to use the expected braking force as the first target braking force of the inner wheel at the next moment if the maximum inner braking force is greater than the expected braking force corresponding to the expected speed, and set the second target braking force corresponding to the outer wheel at the next moment to zero.

8. An electronic device, characterized in that: The electronic device comprises: one or more processors; a storage device 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 implement the braking method for a heavy-load truck as described in any one of claims 1-5.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the program is executed by a processor, the braking method for a heavy-load truck as described in any one of claims 1 to 5 is implemented.

10. A vehicle, characterized in that: The vehicle comprises the electronic device according to claim 8, or comprises the braking device of a heavy-duty truck according to claim 6 or 7.

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