CN117755103B - Control method and device for vehicle torque and storage medium - Google Patents

Abstract

The application relates to the technical field of vehicle control, and provides a vehicle torque control method, a vehicle torque control device and a storage medium. The method comprises the following steps: determining a torque change gradient boundary of the target shaft based on the road surface adhesion coefficient of the target shaft and the longitudinal reference vehicle speed; if the smoothness function activation parameters meet preset smoothness function activation conditions, activating a smoothness function; after the smoothness function is activated, limiting the original request torque of the target shaft by using the drive recovery torque boundary, the original request torque, the drive recovery torque limiting offset coefficient and the target compensation torque to obtain a request torque value; limiting the original torque variation gradient of the target shaft by utilizing the torque variation gradient boundary and the original required torque gradient to obtain a torque variation gradient; the requested torque value and the torque change gradient are sent to the target shaft motor and corresponding torque control is performed. The application solves the problem that the smoothness of the whole vehicle is not considered when the chassis lifting and torsion function is triggered.

Description

Control method and device for vehicle torque and storage medium

Technical Field

The present application relates to the field of vehicle control technologies, and in particular, to a method and apparatus for controlling vehicle torque, and a storage medium.

Background

With the continuous development of new energy automobile technology, torque is an important parameter for new energy automobile control, and has important significance for safe, efficient and high-quality driving experience, for example, in the acceleration process or the climbing process, larger output torque can provide stronger traction force; by optimizing the torque distribution and adjustment strategy, the power demand and energy consumption can be balanced, thereby prolonging the endurance mileage of the vehicle.

Secondly, in the aspect of vehicle stability control, torque plays an important role, namely when the vehicle is attached to a road surface or the torque is greatly changed, particularly when the vehicle is driven at a high speed, suddenly braked or suddenly accelerated, the sudden change of the torque can cause the change of the front-back or left-right weight distribution of the vehicle body, so that in order to keep the balance and stability of the vehicle, a chassis system lifting-torsion request is usually triggered to adjust the posture of the vehicle body, but if the chassis system lifting-torsion request is too frequent or too large in amplitude, the working state of a suspension system can be influenced, and the comfort and stability in the driving process of the vehicle are further influenced.

Therefore, the problem that the smoothness of the whole vehicle is not considered when the chassis lifting and torsion function is triggered exists in the prior art.

Disclosure of Invention

In view of the above, the application provides a method, a device and a storage medium for controlling vehicle torque, so as to solve the problem that the smoothness of the whole vehicle is not considered when the chassis lifting and torsion function is triggered.

In a first aspect of the present application, there is provided a control method of vehicle torque, comprising: determining a driving recovery torque boundary of a target shaft based on the friction circle boundary in the running process of the vehicle; determining a torque variation gradient boundary of a target shaft based on a road surface adhesion coefficient of the target shaft and a longitudinal reference vehicle speed; acquiring a smoothness function activation parameter of the target shaft, and activating the smoothness function of the target shaft if the smoothness function activation parameter meets a preset smoothness function activation condition; after the smoothness function is activated, limiting the original request torque of the target shaft by using the drive recovery torque boundary, the original required torque, the drive recovery torque limiting offset coefficient and the target compensation torque to obtain a request torque value of the target shaft; limiting the original torque variation gradient of the target shaft by utilizing the torque variation gradient boundary and the original required torque gradient to obtain the torque variation gradient of the target shaft; the requested torque value and the torque change gradient are sent to the target shaft motor and corresponding torque control is performed.

In a second aspect of the present application, there is provided a control device for vehicle torque, comprising: a first determination module configured to determine a drive recovery torque boundary of the target shaft based on the friction circle boundary during running of the vehicle; a second determination module configured to determine a torque variation gradient boundary of the target shaft based on a road surface attachment coefficient of the target shaft and a longitudinal reference vehicle speed; the system comprises an activation module, a control module and a control module, wherein the activation module is configured to acquire a smoothness function activation parameter of a target shaft, and activate the smoothness function of the target shaft if the smoothness function activation parameter meets a preset smoothness function activation condition; the request torque limiting module is configured to limit the original request torque of the target shaft by utilizing the drive recovery torque boundary, the original demand torque, the drive recovery torque limiting offset coefficient and the target compensation torque after the smoothness function is activated, so as to obtain a request torque value of the target shaft; the torque gradient limiting module is configured to limit the original torque gradient of the target shaft by utilizing the torque gradient boundary and the original required torque gradient to obtain the torque gradient of the target shaft; and a control module configured to send the requested torque value and the torque variation gradient to the target shaft motor and perform corresponding torque control.

In a third aspect of the application, a storage medium is provided, storing a computer program which, when executed by a processor, implements the steps of the above method.

The at least one technical scheme adopted by the application can achieve the following beneficial effects:

determining a drive recovery torque boundary of the target shaft based on the friction circle boundary; determining a torque change gradient boundary of the target shaft based on the road surface adhesion coefficient of the target shaft and the longitudinal reference vehicle speed; acquiring a smoothness function activation parameter of a target shaft, judging whether a preset smoothness function activation condition is met, and activating the smoothness function of the target shaft when the smoothness function activation parameter of the target shaft meets the preset smoothness function activation condition; when the smoothness function is activated, limiting the original request torque of the target shaft by using the drive recovery torque boundary, the original required torque, the drive recovery torque limiting offset coefficient and the target compensation torque, and limiting the original torque variation gradient of the target shaft by using the torque variation gradient boundary and the original required torque gradient to obtain a request torque value and a torque variation gradient of the target shaft; and then the request torque value and the torque change gradient are sent to a target shaft motor and corresponding torque control is carried out, so that the original request torque and the original torque change gradient of the target shaft are limited, the situation that the tires lose traction due to overhigh torque output of the vehicle is avoided, unnecessary limiting processes can be avoided by setting the smoothness function activation condition, the original request torque and the original torque change gradient are limited, the torque control is carried out on the target shaft according to the request torque value and the torque change gradient obtained after the limiting, the impact on the whole vehicle when the chassis lifting torsion function is triggered due to large torque change is reduced, and the smoothness and the comfort of the whole vehicle are maintained.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings used in the embodiments or the description of the prior art will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present application, and other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.

FIG. 1 is a flow chart of a method for controlling vehicle torque according to an embodiment of the present application;

Fig. 2 is a schematic structural diagram of a vehicle torque control device according to an embodiment of the present application;

Fig. 3 is a schematic structural diagram of an electronic device according to an embodiment of the present application.

Detailed Description

In the following description, for purposes of explanation and not limitation, specific details are set forth such as the particular system architecture, techniques, etc., in order to provide a thorough understanding of the embodiments of the present application. It will be apparent, however, to one skilled in the art that the present application may be practiced in other embodiments that depart from these specific details. In other instances, detailed descriptions of well-known systems, devices, circuits, and methods are omitted so as not to obscure the description of the present application with unnecessary detail.

The terms first, second and the like in the description and in the claims, are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used may be interchanged, as appropriate, such that embodiments of the present application may be implemented in sequences other than those illustrated or described herein, and that the objects identified by "first," "second," etc. are generally of a type, and are not limited to the number of objects, such as the first object may be one or more. Furthermore, in the description and claims, "and/or" means at least one of the connected objects, and the character "/", generally means that the associated object is an "or" relationship.

Furthermore, it should be noted that the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising … …" does not exclude the presence of other like elements in a process, method, article, or apparatus that comprises an element.

A method and apparatus for controlling torque of a vehicle according to an embodiment of the present application will be described in detail with reference to the accompanying drawings.

Fig. 1 is a flowchart of a method for controlling torque of a vehicle according to an embodiment of the present application. As shown in fig. 1, the control method of the vehicle torque includes:

S101, determining a driving recovery torque boundary of a target shaft based on a friction circle boundary during vehicle running.

The friction circle boundary may be one of models describing friction force generated when the wheel contacts the ground, and may be used to represent a boundary of maximum adhesion force between the wheel and the ground, and the size and shape of the friction circle boundary may affect the force that the wheel can transfer to the ground and friction characteristics with the ground, and if the force applied by the wheel exceeds the range that the friction circle boundary can bear, a slip phenomenon may occur, so that the handling performance of the vehicle may be affected. Therefore, the maximum adhesive force of the wheels can be fully exerted by controlling the force exerted by the wheels in the friction circular boundary, and the steering performance of the vehicle is improved.

S102, determining a torque change gradient boundary of the target shaft based on the road surface adhesion coefficient of the target shaft and the longitudinal reference vehicle speed.

S103, acquiring the smoothness function activation parameters of the target shaft, and activating the smoothness function of the target shaft if the smoothness function activation parameters meet preset smoothness function activation conditions.

S104, after the smoothness function is activated, limiting the original request torque of the target shaft by using the drive recovery torque boundary, the original request torque, the drive recovery torque limiting offset coefficient and the target compensation torque to obtain a request torque value of the target shaft.

S105, limiting the original torque change gradient of the target shaft by utilizing the torque change gradient boundary and the original required torque gradient to obtain the torque change gradient of the target shaft.

And S106, transmitting the requested torque value and the torque change gradient to the target shaft motor and performing corresponding torque control.

According to the technical scheme provided by the embodiment of the application, the driving recovery torque boundary and the torque change gradient boundary of the target shaft are calculated, the smoothness function activation parameters of the target shaft are judged based on the driving recovery torque boundary, the torque change gradient boundary and other vehicle state parameters, when the smoothness function activation parameters of the target shaft meet the preset smoothness control function activation conditions, the original request torque and the original torque change gradient are respectively limited by utilizing a preset algorithm to obtain the request torque value and the torque change gradient, so that the vehicle can be more stable in torque control through reasonable torque limitation, the traction performance of the vehicle in different road conditions or running states can be improved, the triggering probability of the chassis lifting torsion function is reduced, the impact force on the whole vehicle after the chassis lifting torsion function is triggered is reduced, and the smoothness of the whole vehicle is maintained.

In some embodiments, the drive recovery torque boundary includes a longitudinal drive torque maximum limit and a longitudinal recovery torque minimum limit; determining a drive recovery torque boundary for the target shaft based on the friction circle boundary, comprising: when the target axle is in a driving positive torque state, calculating to obtain a longitudinal driving torque maximum limit value of the target axle by using the maximum adhesive force of left and right wheels of the target axle, the target axle load, the transverse acceleration and the target wheel radius; when the target axle is in the recovery negative torque state, the longitudinal recovery torque minimum limit value of the target axle is calculated by using the maximum adhesive force of the left wheel and the right wheel of the target axle, the target axle load, the transverse acceleration and the target wheel radius.

The target axle may be a front axle and/or a rear axle, the target wheel may be a front wheel and/or a rear wheel, the target wheel radius may be a front wheel radius and/or a rear wheel radius, and the target axle load may be a front axle load and/or a rear axle load, that is, the drive recovery torque boundaries of the front axle and the rear axle may be independently determined, respectively. It is understood that the torque control processes of the front axle and the rear axle are performed independently, and if the ride comfort functions of the front axle and the rear axle are activated at the same time or in the same state, the torque control is performed at the same time, but the torque control processes of the front axle and the rear axle do not affect each other.

Specifically, the drive recovery torque boundary may include a longitudinal drive torque maximum limit and a longitudinal drive recovery torque minimum limit, and therefore, when the target axle is in a drive positive torque state, the longitudinal drive torque maximum limit of the target axle may be calculated using the maximum adhesion force of the left and right wheels of the target axle, the target axle load, the lateral acceleration, and the target wheel radius. When the target axle is in the recovery negative torque state, the minimum limit value of the longitudinal recovery torque of the target axle can be calculated by using the maximum adhesive force of the left wheel and the right wheel of the target axle, the load of the target axle, the transverse acceleration and the radius of the target wheel.

Further, the target shaft being in a driving positive torque state may represent a state in which the target shaft transmits power of the engine to wheels through the transmission system, thereby allowing the vehicle to move. The target axle is in a state of recovering negative torque, which can represent the reverse torque generated when the target axle is braked or decelerated, namely, the target axle is connected with the target wheel through a transmission system, and when the target wheel is braked or decelerated, the reverse torque can be transmitted to the target axle, and the target axle can bear corresponding load and moment.

The longitudinal drive maximum limit may represent a maximum torque limit that the target axle can withstand during driving, and the longitudinal recovery torque minimum limit may represent a minimum torque limit that the target axle can meet basic requirements for vehicle braking, deceleration, and stability.

Further, a longitudinal drive maximum limit or a longitudinal recovery torque minimum limit may be calculated based on the target axle left and right wheel maximum adhesion, the target axle load, the lateral acceleration, and the target wheel radius, wherein the target axle left and right wheel maximum adhesion may include the target axle left and right wheel maximum adhesion.

As an example, when the front axle is in a driving positive torque state, the longitudinal driving torque maximum limit of the front axle of the embodiment of the present application may be calculated using the following formula:

（1）

Where denotes a maximum limit value of the longitudinal drive torque of the front axle,/> denotes a maximum adhesion force of the left wheel of the front axle,/> denotes a maximum adhesion force of the right wheel of the front axle,/> denotes a front axle load,/> denotes a lateral acceleration, and/> denotes a front wheel radius.

The front axle load in the above formula (1) can be calculated based on the following formula:

Where denotes the mass of the whole vehicle, g denotes the gravitational acceleration,/> denotes the distance of the centroid to the front axis,/> denotes the centroid height,/> denotes the longitudinal acceleration,/> denotes the wheelbase.

The front axle left wheel maximum adhesion in the above formula (1) can be calculated based on the following formula:

Where denotes the front axle left wheel attachment coefficient,/> denotes the lateral acceleration,/> denotes the track, where the track may be used to measure the vehicle width.

The front axle right wheel maximum adhesion in the above formula (1) can be calculated based on the following formula:

wherein denotes the front axle right wheel attachment coefficient.

Further, as another example, when the rear axle is in a driving positive torque state, the longitudinal driving torque maximum limit value of the rear axle of the embodiment of the present application may be calculated by the following formula:

（2）

Where denotes a maximum limit value of the drive torque of the rear axle,/> denotes a maximum adhesion force of the left wheel of the rear axle,/> denotes a maximum adhesion force of the right wheel of the rear axle,/> denotes a rear axle load,/> denotes a lateral acceleration, and/> denotes a rear wheel radius.

The rear axle load in the above formula (2) can be calculated based on the following formula:

The symbols in the formula are identical to the symbols in the previous description, and are not repeated here.

The rear axle left wheel maximum adhesion in the above formula (2) can be calculated based on the following formula:

wherein represents the left wheel attachment coefficient of the rear axle, and the meaning of other symbols is identical to that of the same symbols, and the description is omitted here.

The rear axle right wheel maximum adhesion in the above formula (2) can be calculated based on the following formula:

Wherein represents the right wheel attachment coefficient of the rear axle, and the meaning of other symbols is identical to that of the same symbols, and the description is omitted here.

Further, as yet another example, when the front axle is in a recuperation negative torque state, the longitudinal recuperation torque minimum limit of the front axle of an embodiment of the present application may be calculated based on the following formula:

Wherein represents the minimum limit value of the longitudinal recovery torque of the front axle, and the other symbols have the same meaning as the symbols in the previous description, and are not repeated here.

It should be noted that, the negative sign may indicate the direction of the torque, and indicate the torque generated during the process of converting kinetic energy into electric energy or other energy by the power system and storing or using the electric energy or other energy during the deceleration or braking of the vehicle, and the negative sign is not used to indicate the magnitude of the torque value, but is not limited herein.

Further, as yet another example, when the rear axle is in the recovered negative torque state, the longitudinal recovered torque minimum limit value of the rear axle of the embodiment of the present application may be calculated by the following formula:

Wherein represents the minimum limit value of the longitudinal recovery torque of the rear axle, the meanings and calculation principles of other symbols are identical to those of the same symbols, and are not repeated herein, and the negative sign is a vector sign and does not represent the magnitude.

It should be noted that, the lateral acceleration in the above formulas may be obtained by a vehicle-mounted acceleration sensor, or may be determined based on a position change rate obtained by a global positioning system, which is not limited herein.

The values of the front axle left wheel attachment coefficient, the front axle right wheel attachment coefficient, the rear axle left wheel attachment coefficient and the rear axle right wheel attachment coefficient can be in a range from 0 to 1, the range can represent the change from no friction to maximum friction of the target wheel, the values of the attachment coefficients are determined according to the situation during calculation, and the specific attachment coefficient values are not limited.

According to the method of the embodiment, the driving recovery torque boundary of the target shaft can be calculated and used as one of the smoothness function activation parameters of the target shaft, and the original request torque is limited when the driving recovery torque boundary is not within the range, so that a torque value which can be stably output is obtained, and the smoothness of the whole vehicle can be maintained when the torque change is large or the chassis lifting torsion function is triggered.

In some embodiments, if the ride performance activation parameter meets a preset ride performance activation condition, activating the ride performance of the target shaft includes: and if the smoothness function activation parameter simultaneously meets the condition that the longitudinal reference vehicle speed is lower than the preset vehicle speed, the minimum road surface attachment coefficient of the target shaft is smaller than the preset coefficient, and the original required torque of the target shaft does not belong to the driving recovery torque boundary range and the original required torque gradient of the target shaft does not belong to the torque change gradient boundary range, activating the smoothness function.

Specifically, acquiring a smoothness function activation parameter of a target shaft, wherein the activation parameter can comprise a longitudinal reference speed of a vehicle, a minimum road surface attachment coefficient of the target shaft, an original required torque of the target shaft and an original required torque gradient of the target shaft, and activating a smoothness function only when the smoothness function activation parameters of the target shaft meet preset smoothness function activation conditions; if any one of the current smoothness function activation parameters does not meet the corresponding preset smoothness function activation conditions, the smoothness function is not activated.

It should be noted that, the judgment of the ride performance function activation parameters of the front axle and the rear axle may be independent, that is, the ride performance function activation parameters of the front axle and the rear axle may simultaneously satisfy the corresponding preset ride performance function activation conditions; the method can also be used for solving the problem that the smoothness function activation parameters of the front axle meet preset smoothness function activation conditions of the front axle and the smoothness function activation parameters of the rear axle do not meet preset smoothness function activation conditions of the rear axle; the comfort function activation parameters of the rear axle can also meet the preset comfort function activation conditions of the rear axle, and the comfort function activation parameters of the front axle do not meet the preset comfort function activation conditions of the front axle, that is, it can be understood that the comfort function activation judgment of the front axle and the rear axle are independently performed without mutual influence, but the method is not limited herein.

The driving recovery torque boundary may include a longitudinal driving torque maximum limit value and a longitudinal recovery torque minimum limit value, so the original required torque does not belong to the driving recovery torque boundary range, and may be that the original required torque is greater than the longitudinal driving torque maximum limit value or that the original required torque is less than the longitudinal recovery torque minimum limit value.

Further, the torque-change gradient boundary may include a driving torque-up gradient threshold and a recovery torque-down gradient threshold, so the original demand torque gradient does not fall within the torque-change gradient boundary range, and may be greater than the driving torque-up gradient threshold or less than the recovery torque-down gradient threshold.

The original required torque of the target shaft and the original required torque gradient of the target shaft can be input by a user, and when the original required torque is in the range of the driving recovery torque boundary and the original required torque gradient is in the range of the torque change gradient boundary, the requirement of stable running of the vehicle can be met, and further limitation on the torque is not needed.

That is, when the target shaft is in the driving positive torque state, the original required torque is greater than the maximum limit value of the longitudinal driving torque, or when the target shaft is in the recovering negative torque state, the original required torque is smaller than the minimum limit value of the longitudinal recovering torque, and the limitation is required, that is, the preset condition corresponding to the original required torque in the preset smoothness function activating condition of the target shaft is satisfied.

That is, when the target shaft is in the driving positive torque state, if the ride comfort function activation parameter simultaneously satisfies: the longitudinal reference vehicle speed is lower than the preset vehicle speed, the minimum road surface attachment coefficient of the target shaft is smaller than the preset coefficient, the original required torque of the target shaft is larger than the maximum limit value of the longitudinal driving torque, the original required torque gradient of the target shaft is larger than the critical value of the driving torque rising gradient, and the smoothness function of the target shaft can be activated.

When the target shaft is in the recovery negative torque state, if the smoothness function activation parameters simultaneously meet the following conditions: the longitudinal reference vehicle speed is lower than the preset vehicle speed, the minimum road surface attachment coefficient of the target shaft is smaller than the preset coefficient, the original required torque of the target shaft is smaller than the minimum limit value of the longitudinal recovery torque, the original required torque gradient of the target shaft is smaller than the gradient critical value of the recovery torque, and the smoothness function of the target shaft can be activated.

Further, the longitudinal reference vehicle speed may be a speed in the forward direction of the vehicle, and as an example, the preset vehicle speed of the longitudinal reference vehicle speed may be 80km/h, but is not particularly limited herein.

The minimum road surface adhesion coefficient of the target shaft may be a ratio of a minimum friction force required by the target shaft during running of the vehicle to a pressure perpendicular to the road surface, which reflects a friction performance of the road surface, and as an example, the preset coefficient of the minimum road surface adhesion coefficient may be 0.5, but is not particularly limited thereto.

Before the activation of the smoothness function of the target shaft is determined, a torque change gradient boundary, that is, a driving torque rising gradient critical value and a recovery torque falling gradient critical value of the target shaft, that is, a driving torque rising gradient critical value of the front shaft and the rear shaft, and a recovery torque falling gradient critical value of the front shaft and the rear shaft, is also calculated.

The critical value of the rising gradient of the driving torque can represent the limitation of the change rate of the output torque of an engine or a motor in unit time when the vehicle is driven, the critical value of the rising gradient of the driving torque is set to avoid unstable vehicle bodies or other safety problems caused by sudden increase of the torque, and the critical value of the falling gradient of the recovery torque can represent the limitation of the change rate of the torque when the recovery converter recovers the torque from a target wheel to a power system, and represents the limitation rate of the torque recovery of the vehicle in the braking or decelerating process.

Further, the road surface attachment coefficient of the target shaft and the longitudinal reference vehicle speed can be utilized to obtain a driving torque rising gradient critical value or a recovery torque falling gradient critical value of the target shaft.

As one example, when the front axle is in a driving positive torque state, the driving torque up gradient threshold value of the front axle may be calculated by the following formula:

Where denotes a drive torque up gradient threshold value of the front axle,/> denotes a longitudinal reference vehicle speed,/> denotes a road surface adhesion coefficient of the front axle, and/> denotes a curve determined based on the longitudinal reference vehicle speed and the road surface adhesion coefficient of the front axle.

As another example, when the front axle is in the recovered negative torque state, the recovered torque drop gradient threshold value of the front axle may be calculated using the following formula:

Wherein is the recovery torque drop gradient threshold value of the front axle, and the other symbols are the same as the same symbols as above, and will not be described here.

As yet another example, when the rear axle is in a driving positive torque state, the driving torque up gradient threshold value of the rear axle may be calculated using the following formula:

Where is a drive torque up gradient threshold value of the rear axle, v > is a road surface adhesion coefficient of the rear axle, and v > is a curve determined based on the longitudinal reference vehicle speed and the road surface adhesion coefficient of the rear axle.

As yet another example, when the rear axle is in the recovered negative torque state, the recovered torque drop gradient threshold value of the rear axle may be calculated by the following formula:

Wherein is the recovery torque drop gradient threshold value of the rear axle, and the other symbols are the same as the same symbols as above, and will not be described here.

The road surface adhesion coefficient of the front axle can be the ratio of the friction force between the front axle and the road surface to the pressure perpendicular to the road surface, the road surface adhesion coefficient of the rear axle can be the ratio of the friction force between the rear axle and the road surface to the pressure perpendicular to the road surface, and the road surface adhesion coefficient can reflect the traction capability and the steering performance of the vehicle under different road surface conditions. The road surface adhesion coefficients of the front axle and the rear axle can be obtained by inquiring vehicle information, but the road surface adhesion coefficients of the front axle and the rear axle are generally related to weather conditions, road surface conditions, and the like, so can also be obtained by measuring the friction between tires and the road surface by setting a vehicle-mounted test program and related equipment, but are not limited thereto.

Further, if the smoothness activating parameter of the target shaft meets the preset smoothness function activating condition, after the torque change gradient boundary is obtained, the original torque change gradient of the target shaft can be limited through a preset formula to obtain the torque change gradient of the target shaft.

As one example, the torque change gradient of the front axle may be calculated using the following formula:

Wherein denotes a torque gradient of the front axle, denotes an original required torque gradient of the front axle, denotes a driving torque gradient threshold value of the front axle, denotes a recovery torque gradient threshold value of the front axle, and is a representative symbol of the activation of the ride comfort function of the front axle.

The formula shows that when is adopted, the smoothness function of the front axle is activated, at the moment, the minimum value of the original required torque gradient and the driving torque rising gradient critical value can be taken, the minimum value of the original required torque gradient and the driving torque rising gradient critical value can be compared with the recovery torque falling gradient critical value of the front axle, the maximum value of the comparison result is taken as the torque change gradient obtained after limiting, and the torque control is carried out according to the torque change gradient obtained after limiting; when/> , it indicates that the front axle ride function is not activated, at which time the front axle may be torque controlled with the original demand torque gradient.

As another example, the torque change gradient of the rear axle may be calculated using the following formula:

Wherein is torque change gradient of the rear axle, i > is original demand torque gradient of the rear axle, is driving torque rising gradient critical value of the rear axle, i > is recovery torque falling gradient critical value of the rear axle, i > is representative symbol of the condition of activating the ride comfort function of the rear axle, i > indicates that the ride comfort function of the rear axle is activated, and i > indicates that the ride comfort function of the rear axle is not activated.

The principle of calculation of the torque gradient of the front axle and the rear axle is the same, and the principle of calculation of the torque gradient of the rear axle will not be described here.

According to the method of the embodiment, the condition of activating the smoothness function of the target shaft of the vehicle is limited, the situation that the load of the vehicle is increased due to the fact that unnecessary torque limiting process occurs is avoided, and the smoothness of the front shaft and the rear shaft are independent in judgment, so that the smoothness of the whole vehicle is ensured, the flexibility of corresponding torque control of the target shaft motor is also improved, in addition, after the smoothness function of the target shaft is activated, the target shaft motor can be controlled to control the torque according to the torque change gradient through limiting the original torque change gradient, and the smoothness of the vehicle body is controlled.

In some embodiments, the target compensation torque comprises an unstable compensation torque and a stable compensation torque, and prior to limiting the original requested torque of the target shaft with the drive recovery torque boundary, the original demand torque, the drive recovery torque limit offset coefficient, and the target compensation torque to obtain the requested torque value of the target shaft, further comprising: acquiring the current state of a target wheel; if the current state of the target wheel is an unstable state, the stable compensation torque is 0, and the unstable compensation torque is determined based on the acceleration of the target wheel and the slip ratio of the target wheel; if the current state of the target wheel is a stable state, the unstable compensation torque is 0, and the stable compensation torque is determined based on the attachment coefficient of the target wheel.

Specifically, before the requested torque value of the target axle is calculated, the target compensation torque, that is, the unstable compensation torque or the stable compensation torque of the target axle, may be calculated, so as to meet the requirement that the corresponding target axle of the wheel outputs an appropriate requested torque value in different states.

The target compensation torque is torque compensation in the process of limiting the original request torque, if the current states of the target wheels are different, the required target compensation torque is different, and it should be understood that the target wheels can be wheels corresponding to the target axle, namely wheels corresponding to the axles with activated ride comfort function.

Therefore, to calculate the target compensation torque, the current state of the target wheel when the smoothness function of the target axle is activated can be obtained, whether the current state of the target wheel is a stable state or an unstable state is judged, if the current state of the target wheel is an unstable state, the acceleration of the target wheel and the slip ratio of the target wheel can be utilized to determine the unstable compensation torque, and at the moment, the stable compensation torque can be 0, namely the stable compensation torque is regarded as not existing; if the current state of the target wheel is a stable state, the stable compensation torque can be determined by using the attachment coefficient of the target wheel, and the unstable compensation torque can be 0 at this moment, namely, the unstable compensation torque is regarded as not existing, namely, the current state of the target wheel when the smoothness function of the target shaft is activated can be used as the basis for selecting and calculating the algorithm logic of the target compensation torque.

In addition, the current state of the target wheel may be obtained by starting to obtain the current state of the target wheel corresponding to the target axle when the activation of the ride comfort function of the target axle is detected, and the current state of the target wheel may be obtained in real time for real-time monitoring of the current state of the target wheel, or may be obtained at intervals of a preset time, but the preset time of the intervals should not be too large, and the intervals may be 50 milliseconds as an example, but are not limited herein.

It should be noted that, during the activation of a ride comfort function, only one kind of algorithm logic of the target compensation torque may be used to determine the target compensation torque, that is, when the ride comfort function of the target axle is activated, if the current state of the target wheel is an unstable state, the algorithm logic of the unstable compensation torque is used to calculate the target compensation torque, and if during the activation of the ride comfort function, the current state of the target wheel is changed from the unstable state to the stable state, the target compensation torque is kept at an upper period value, that is, the target compensation torque after the target wheel is changed into the stable state may be determined based on the unstable compensation torque before the target wheel is changed into the stable state, and the target compensation torque at this time may be regarded as the stable compensation torque, but is calculated by using the unstable compensation torque calculation logic, so as to ensure that the target compensation torque after the target wheel is changed into the stable state is closest to the truly required target compensation torque, and the target compensation torque after the target wheel is changed into the stable state may be determined by using the acceleration and the slip ratio when the target wheel is changed into the stable state.

And if the target wheel enters an unstable state again, calculating the unstable compensation torque by using the acceleration of the target wheel, the slip rate of the target wheel and the initial value of the unstable compensation torque after entering the unstable state again, wherein the initial value of the unstable compensation torque can be the last period output value, namely the target compensation torque in the stable state before the target wheel enters the unstable state.

Similarly, when the ride comfort function of the target axle is activated, if the current state of the target wheel is in a stable state, during the activation period of the ride comfort function, the current state of the target wheel is changed from the stable state to the unstable state, and the target compensation torque keeps an upper period value, that is, the target compensation torque after the target wheel is changed to the unstable state can be determined based on the stable compensation torque before the target wheel is changed to the unstable state, and similarly, the target compensation torque after the target wheel is changed to the unstable state can be determined by using the target wheel attachment coefficient when the target wheel is changed to the unstable state, and the target compensation torque can be regarded as the unstable compensation torque at the moment, but is logically calculated by using the stable compensation torque algorithm, and then if the target wheel is changed to the stable state again, the initial value of the stable compensation torque after the target wheel is changed to the upper period output value, that is, the target compensation torque after the target wheel is changed to the unstable state before the stable state.

Further, if the ride comfort function of the target shaft is not activated, then either the unstable compensation torque or the stable compensation torque of the target shaft may be considered to be absent, it being understood that the ride comfort function being deactivated may include exiting the ride comfort function activated state after the ride comfort function is activated.

In addition, the current state of the target wheel may be determined based on the target wheel speed change rate, and when the absolute value of the target wheel speed change rate is smaller than Th1 and the differential absolute value of the target wheel speed change rate is smaller than Th2, the current state of the target wheel may be determined to be a stable state, or else the current state of the target wheel may be an unstable state, wherein Th1 may be 10, and Th2 may be 60, but is not limited thereto.

Further, if the smoothness function of the target axle is activated, after the current state of the target wheel is obtained, the unstable compensation torque of the target axle or the stable compensation torque of the target axle can be calculated, and then the driving recovery torque boundary and other parameters obtained by the calculation can be combined, and the request torque value of the target axle can be obtained through the limitation of a preset algorithm.

As one example, the original requested torque of the front axle may be limited to a requested torque value using the following formula:

（3）

Where denotes a requested torque value of the front axle,/> denotes an original requested torque of the front axle,/> denotes a drive torque limitation offset coefficient of the front axle,/> denotes a longitudinal drive torque maximum limit value of the front axle,/> denotes a recovery torque limitation offset coefficient of the front axle,/> denotes a front axle longitudinal recovery torque minimum limit value,/> denotes an unstable compensation torque of the front axle,/> denotes a stable compensation torque of the front axle, and/> is a representative symbol of the front axle ride comfort function activation condition.

Further, in the formula (3), when is indicated that the ride comfort function of the front axle is activated, it should be understood that when the current state of the front axle wheel is an unstable state, the stable compensation torque may be considered to be absent, and the original required torque may be limited by using the original required torque, the driving torque limiting offset coefficient, the recovery torque limiting offset coefficient, the longitudinal driving torque maximum limit value, the longitudinal recovery torque minimum limit value, and the unstable compensation torque of the front axle to obtain the required torque value.

When the current state of the front axle wheels is a stable state, the original required torque of the front axle, the driving torque limiting offset coefficient, the recovery torque limiting offset coefficient, the longitudinal driving torque maximum limit value, the longitudinal recovery torque minimum limit value and the stable compensation torque can be used for limiting the original required torque to obtain a required torque value according to the fact that the unstable compensation torque does not exist.

In addition, when indicates that the smoothness function of the front axle is not activated, the original required torque can be sent to the front axle motor to control the torque of the front axle.

The general values of the driving torque limiting offset coefficient and the recovery torque limiting offset coefficient of the front axle can be 0.5-1.5, and it can be understood that the driving recovery torque limiting offset coefficient can be calibrated through the longitudinal acceleration change rate of the vehicle after the ride comfort function is activated, the offset coefficient is close to 0.5 when the longitudinal acceleration change rate is overlarge, and the offset coefficient is close to 1.5 when the longitudinal acceleration change rate is overlarge.

In equation (3), the front axle unsteady compensation torque can be obtained based on the following equation:

（4）

Where denotes accumulation with/> ,/> denotes unsteady compensating torque gradient of the front axle,/> denotes smoothness function activation of the front axle,/> denotes smoothness function deactivation of the front axle.

The equation (4) may be expressed as that, when the ride comfort function of the front axle is activated, if the current state of the front wheel is an unstable state, the unstable compensation torque of the front axle may be calculated by accumulating the unstable compensation torque gradient based on the initial value of the unstable compensation torque. It should be appreciated that the initial value of the unstable compensating torque in the initial state may be 0, and the initial state may be the current state of the target wheel that is determined for the first time when the ride comfort function is activated, where the initial state may be regarded as an unstable state in which the front wheel is first entered, that is, in an unstable state in which the front wheel is first entered, the initial value of the unstable compensating torque is 0.

Further, during the activation period of a ride comfort function, if the current state of the front wheel enters the unstable state from the unstable state, and then enters the unstable state, when calculating the unstable compensation torque in the unstable state, the initial value of the unstable compensation torque may be the output value of the previous period, and the principle thereof is already described in the foregoing, and will not be repeated here.

In addition, if the smoothness function of the front axle is not activated, the unstable compensation torque of the front axle may be 0, i.e. it is regarded that there is no unstable compensation torque.

Further, the front axle unsteady compensating torque gradient in equation (4) may be derived based on the following equation:

(5)

Where denotes the acceleration of the front wheel,/> denotes the slip ratio of the target wheel, here may denote the slip ratio of the front wheel, and each of/> and/> may denote a two-dimensional curve obtained based on the acceleration of the front wheel and the slip ratio of the front wheel, which may also be regarded as an unstable compensation torque gradient table of the front wheel in different states obtained based on the acceleration of the front wheel and the slip ratio of the front wheel.

Equation (5) may indicate that, when the front wheel is in a driving positive torque state, the unstable compensation torque gradient of the front axle may be determined based on , the two-dimensional curve/> may be calibrated by a real vehicle debugging, in the real vehicle debugging calibration, the "preventing the wheel from slipping substantially" is taken as a main target, and the debugging calibration rule may be: the smaller the/> , the smaller the lookup gradient, the smaller the/> , the smaller the lookup gradient, and all negative, at most 0, i.e. when the front wheels all enter steady state, the/> . /(I)

When the front wheel is in a recovery negative torque state, the unstable compensation torque gradient of the front axle can be determined based on , the/> can be calibrated by real vehicle debugging, in the real vehicle debugging calibration, the 'preventing the wheel from sliding greatly' is taken as a main target, and the debugging calibration rule can be as follows: the larger the/(), the larger the lookup gradient, the larger the/(), the larger the lookup gradient, and both positive values, with a minimum of 0, i.e. when the front wheels all enter steady state, the/> .

Wherein may be determined based on the front wheel first wheel speed, i.e., according to . Where,/> denotes the front axle left wheel first wheel speed, denotes the front axle right wheel first wheel speed, which may be the rate of change of the rotational speed of the wheel over time, and,/> may be expressed as the maximum value of the absolute value of the derivative of the front axle left wheel first wheel speed and the absolute value of the derivative of the front axle right wheel first wheel speed.

Can be derived based on the target wheel second wheel speed and the target wheel reference speed,/> can be derived based on the following equation:

Wherein corresponds to the second wheel speed of each target wheel, namely the second wheel speed of the left wheel of the front axle/> , the second wheel speed of the right wheel of the front axle/> , the second wheel speed of the left wheel of the rear axle/> , and the second wheel speed of the right wheel of the rear axle/> , and the second wheel speed of the target wheel can be the actual rotation speed of the target wheel. The/> may represent a target wheel reference speed, which may be the speed at which the longitudinal reference vehicle speed of the vehicle is converted onto each target wheel, which may include the front axle left wheel reference speed/> , the front axle right wheel reference speed/> , the rear axle left wheel reference speed/> , the rear axle right wheel reference speed/> .

The slip ratio of the specific target wheel may select a corresponding calculation mode according to the actual situation, and as an example, when the slip ratio of the front axle left wheel needs to be calculated, the slip ratio may be calculated according to the following formula:

In the embodiment of the application, the unstable compensation torque gradient can be determined based on the acceleration of the target wheel and the slip ratio of the target wheel, as an example, when the front wheel is in the state of recovering the negative torque, the larger the is, the larger the lookup gradient is, the larger the slip ratio of the left wheel of the front axle and the slip ratio of the right wheel of the front axle is, the larger the lookup gradient is, and the specific situation and the corresponding value can be determined through real vehicle debugging, and the description is not made here.

In addition, the front wheels in the driving positive torque state may be a torque state in which the front wheels are driven by an engine or a motor during running, resulting in pushing the vehicle forward; the front wheels being in the recovered negative torque state may represent a negative torque state that is generated when the front wheels are subjected to reverse rotation of the brake system or the motor during running.

Further, the steady compensation torque of the front axle in the formula (3) can be obtained based on the following formula:

（6）/>

where denotes accumulation with/> ,/> denotes steady compensating torque gradient of the front axle,/> denotes front axle ride function active,/> denotes front axle ride function inactive.

The formula (6) may be expressed as that, when the front axle ride comfort function is activated, if the current state of the front wheel is a stable state, the stable compensation torque may be obtained by accumulating the stable compensation torque gradients based on the initial value of the stable compensation torque, the initial value of the stable compensation torque in the initial state may be 0, and the initial state at this point may be regarded as a stable state in which the front wheel enters for the first time.

Further, during the activation of a ride comfort function, if the current state of the front wheel enters the stable state after entering the non-stable state from the stable state, the initial value of the stable compensation torque can maintain the output value of the previous period when calculating the stable compensation torque in the stable state, and the principle is described in the foregoing, and will not be repeated here.

In addition, when the ride comfort function of the front axle is not activated, the stability compensation torque of the front axle may be 0, i.e., it is considered that there is no stability compensation torque.

Further, the steady compensation torque gradient of the front axle in equation (6) can be obtained based on the following equation:

Wherein is the front axle left wheel attachment coefficient,/> is the front axle right wheel attachment coefficient,/> and/> each represent a one-dimensional curve obtained based on the maximum value of the front axle left wheel attachment coefficient and the front axle right wheel attachment coefficient, and the one-dimensional curve can be regarded as a stable compensation torque gradient table of the front wheel under different states.

When the front wheel is in a driving positive torque state, the stable compensation torque gradient of the front axle can be all positive values, and can be determined specifically based on a one-dimensional curve , wherein the one-dimensional curve can be calibrated through real vehicle debugging, and the calibration rule can be as follows: the smaller the front axle left wheel attachment coefficient and the front axle right wheel attachment coefficient are, the smaller the stability compensation torque gradient is, and the torque response condition can be calibrated based on the full accelerator acceleration after the vehicle runs from low attachment to high attachment. That is, in the calibration, the calibration is first performed based on the attachment coefficient of the front wheel, and then the calibration value is further updated based on the torque response condition. Wherein the front wheel attachment coefficient may include a front axle right wheel attachment coefficient and a front axle left wheel attachment coefficient.

When the front wheel is in a recovery negative torque state, the stable compensation torque gradient of the front axle can be all negative, and can be determined specifically based on a one-dimensional curve , and the calibration rule of the acquisition/> can be as follows: the smaller the attachment coefficient of the front wheel is, the larger the stable compensation torque gradient is, and the calibration is carried out based on the recovery torque condition when the vehicle slides and recovers after traveling from a low attachment road surface to a high attachment road surface, and the calibration is updated according to the recovery torque condition when the vehicle slides and recovers after traveling from a low attachment road surface to a high attachment road surface.

In this way, after the smoothness function of the front axle is activated, if the current state of the front wheel is a stable state, the stable compensation torque of the front axle is obtained by utilizing the corresponding algorithm, and the original required torque, the driving recovery torque boundary and the driving recovery torque limiting offset coefficient of the front axle are combined to obtain the required torque value of the front axle; and if the current state of the front wheel is an unstable state, obtaining an unstable compensation torque by utilizing the corresponding algorithm, and obtaining a request torque value of the front axle by combining the original required torque of the front axle, the driving recovery torque boundary and the driving recovery torque limiting offset coefficient.

If the smoothness function of the front axle is not activated, the original required torque of the front axle can be sent to the front axle motor and corresponding torque control can be performed.

As another example, the original requested torque of the rear axle may be limited to a requested torque value of the rear axle using the following formula:

（7）

Where denotes a requested torque value of the rear axle,/> denotes an original requested torque of the rear axle,/> denotes a rear axle drive torque limitation offset coefficient,/> denotes a longitudinal drive torque maximum limit value of the rear axle,/> denotes a recovered torque limitation offset coefficient of the rear axle,/> denotes a rear axle longitudinal recovered torque minimum limit value,/> denotes an unstable compensation torque of the rear axle, and/> denotes a stable compensation torque of the rear axle.

Likewise, the drive torque limit offset coefficient and the recovery torque limit offset coefficient of the rear axle may generally take values of 0.5 to 1.5.

The unsteady compensation torque of the rear axle in the formula (7) can be obtained based on the following formula:

Where denotes the unsteady compensating torque gradient of the rear axle,/> denotes the unsteady compensating torque gradient of the rear axle/> accumulation.

Further, the unsteady compensating torque gradient of the rear axle may be obtained based on the following formula:

Where denotes the acceleration of the rear wheel, where/> may denote the slip ratio of the rear wheel, and/> and denote two-dimensional curves determined based on the acceleration of the rear wheel and the slip ratio of the rear wheel, which may be regarded as an unstable compensation torque gradient table of the rear wheel in different states based on the acceleration of the rear wheel and the slip ratio of the rear wheel.

When the rear wheel is in a positive torque driving state, the unstable compensation torque gradient of the rear axle can be determined based on , and when the rear wheel is in a negative torque recovering state, the unstable compensation torque gradient of the rear axle can be determined based on/> , and the/> and/> are real vehicle debugging calibration, and the calibration rule is the same as that of the unstable compensation torque gradient of the front axle.

Further, the steady compensation torque of the rear axle in the formula (7) can be obtained based on the following formula:

Where denotes the steady compensation torque gradient of the rear axle,/> denotes the steady compensation torque gradient of the rear axle/> accumulation.

Likewise, the steady compensation torque gradient for the rear axle can be derived based on the following equation:

Where denotes the rear axle left wheel attachment coefficient,/> denotes the rear axle right wheel attachment coefficient,/> and/> each denote a one-dimensional curve determined based on the maximum values of the rear axle left wheel attachment coefficient and the rear axle right wheel attachment coefficient, which can be regarded as a steady compensation torque gradient table for the rear wheel in different states.

The principle and the algorithm logic in the formula (7) are the same as those in the formula (3), and are not described herein too much, and if the same symbols are given in the different formulas, the same symbols are the same meaning.

According to the method of the embodiment, after the smoothness function of the target axle is activated, the current state of the target wheel corresponding to the target axle is obtained, when the current state of the target wheel is in an unstable state, the unstable compensation torque of the target axle is calculated, or when the current state of the target wheel is in a stable state, the stable compensation torque of the target axle is calculated, further, the request torque value of the target axle is obtained by utilizing the unstable compensation torque and other parameters, or the request torque value of the target axle is obtained by utilizing the stable compensation torque and other parameters, so that the original request torque can be limited, and the calculated request torque value is sent to the target axle motor to perform corresponding torque control, so that the smoothness of the vehicle is maintained.

In some embodiments, if the current state of the target wheel is an unstable state, the stable compensation torque is 0, and determining the unstable compensation torque based on the acceleration of the target wheel and the slip ratio of the target wheel comprises: calculating the acceleration of the target wheel by using the first wheel speed of the target wheel; calculating the slip rate of the target wheel by using the reference speed of the target wheel and the second wheel speed of the target wheel; determining an unstable compensation torque gradient according to the acceleration and the slip ratio; and obtaining the unstable compensation torque according to the unstable compensation torque initial value and the unstable compensation torque gradient.

Specifically, when the current state of the target wheel is an unstable state, the acceleration of the target wheel can be calculated by using the first wheel speed of the target wheel, the slip rate of the target wheel can be calculated by using the reference speed of the target wheel and the second wheel speed of the target wheel, the unstable compensation torque gradient is determined according to the acceleration of the target wheel and the slip rate of the target wheel, and after the unstable compensation torque gradient is obtained, the unstable compensation torque is accumulated on the initial value of the unstable compensation torque by using the unstable compensation torque gradient.

The first wheel speed of the target wheel is used for calculating the acceleration of the target wheel and can be the change rate of the rotation speed of the target wheel along with time; the target wheel second wheel speed may be an actual rotation speed of the target wheel, which may be measured by a wheel sensor or a vehicle speed sensor.

The logic for calculating the unstable compensation torque is already described above and will not be described here.

According to the method of the embodiment, the unstable compensation torque of the target wheel can be determined according to the acceleration of the target wheel and the slip rate of the target wheel, so that when the target wheel is in an unstable state, the original request torque can be compensated according to the calculated unstable compensation torque, and the request torque value can meet the stability of vehicle driving.

In some embodiments, prior to determining the unsteady compensating torque gradient based on acceleration and slip ratio, further comprising: obtaining an unstable compensation torque gradient table according to the acceleration and the slip ratio; wherein acceleration is positively correlated with an unstable compensation torque gradient, slip ratio is positively correlated with an unstable compensation torque gradient; when the target wheel is in a driving positive torque state, the maximum value of the unstable compensation torque gradient is a preset unstable compensation torque gradient; when the target wheel is in the recovered negative torque state, the minimum value of the unstable compensating torque gradient is a preset unstable compensating torque gradient.

Specifically, after the ride comfort function of the target axle is activated, if the current state of the target wheel is an unstable state, before the unstable compensation torque is determined, an unstable compensation torque gradient table can be obtained according to the acceleration of the target wheel and the slip ratio of the target wheel, and then the unstable compensation torque corresponding to the current state of the wheel is searched according to the unstable compensation torque gradient table, and in the process of obtaining the unstable compensation torque gradient table, the following steps can be set: acceleration is positively correlated with an unstable compensating torque gradient, and slip ratio is positively correlated with an unstable compensating torque gradient.

It should be appreciated that the two-dimensional curve determined based on the acceleration of the target wheel and the slip ratio of the target wheel may be regarded as an unstable compensation torque gradient table of the target axle, that is, the two-dimensional curve determined in the foregoing, and, as an example, the two-dimensional curves and/> in the foregoing may be regarded as unstable compensation torque gradient tables corresponding to the driving positive torque state and the recovering negative torque state of the front wheel respectively in the embodiment of the present application, and the unstable compensation torque gradient table may be obtained through real vehicle debugging.

Further, when the target wheel is in the driving positive torque state, the maximum value of the unstable compensation torque gradient is a preset unstable compensation torque gradient, the preset unstable compensation torque gradient may be 0, it should be understood that, when the target wheel is in the driving positive torque state, in order to ensure stability and controllability of the vehicle, a more appropriate requested torque value is obtained, and an unnecessary part of the original requested torque may be offset by using the unstable compensation torque, so that the unstable compensation torque gradient may be a negative value, and at this time, the maximum value of the unstable compensation torque gradient may be 0, that is, the preset unstable compensation torque gradient may be 0, that is, the target axle enters a stable state. Similarly, when the target wheel is in the recovered negative torque state, the unstable compensation torque can be used for compensating the insufficient part of the original required torque, the unstable compensation torque gradient can be positive, and the minimum value of the unstable compensation torque gradient can be 0, namely, the target shaft enters the stable state.

According to the method of the above embodiment, the unstable compensation torque gradient table is obtained according to a predetermined rule, so that the unstable compensation torque gradient corresponding to the current state of the target wheel can be selected to obtain the unstable compensation torque.

In some embodiments, the target wheel attachment coefficient includes a target axle left wheel attachment coefficient and a target axle right wheel attachment coefficient, the unsteady compensation torque is 0 if the target wheel current state is a steady state, and determining the steady compensation torque based on the target wheel attachment coefficient includes: determining a steady compensation torque gradient based on the target axle left wheel attachment coefficient and the target axle right wheel attachment coefficient; and obtaining the stable compensation torque according to the stable compensation torque initial value and the stable compensation torque gradient.

Specifically, the steady compensation gradient may be determined based on the attachment coefficient of the target wheel, that is, a one-dimensional curve determined based on the target axle left wheel attachment coefficient and the target axle right wheel attachment coefficient may be established based on a preset calibration rule so as to determine the steady compensation torque gradient of the target axle, the calibration rule may be different when the target wheel is in a different state, the attachment coefficient of the target wheel may be positively correlated with the steady compensation torque gradient when the target wheel is in a driving positive torque state, and the attachment coefficient of the target wheel may be negatively correlated with the steady compensation torque gradient when the target wheel is in a recovering negative torque state.

After determining the steady compensation torque gradient of the target shaft, the steady compensation torque gradient can be accumulated on the basis of the initial value of the steady compensation torque to obtain the steady compensation torque, and the steady compensation torque can be used for complementing or counteracting part of the original required torque of the target shaft to obtain the required torque value.

The principles of the embodiments of the present application have been described above and are not repeated here.

According to the method of the embodiment, when the smoothness function of the target axle is activated, if the target wheel is in a stable state, a stable compensation torque gradient can be obtained according to the attachment coefficient of the target wheel, and the stable compensation torque is further obtained based on the initial value of the stable compensation torque, so that the smoothness of the vehicle is improved, and the situation that the vehicle is unstable due to overlarge torque difference among the wheels can be avoided.

In some embodiments, prior to determining the steady compensation torque gradient based on the target axle left wheel attachment coefficient and the target axle right wheel attachment coefficient, further comprising: obtaining a stable compensation torque gradient table according to the target axle left wheel attachment coefficient and the target axle right wheel attachment coefficient; wherein the stability compensation torque gradient is positively correlated with the attachment coefficient of the target wheel when the target wheel is in a driving positive torque state; the stability compensation torque gradient is inversely related to the attachment coefficient of the target wheel when the target wheel is in the recovered negative torque state.

Specifically, in the process of obtaining the steady compensation torque gradient table, it may be set that the steady compensation torque gradient is positively correlated with the attachment coefficient of the target wheel when the target wheel is in the driving positive torque state, and that the steady compensation torque gradient is negatively correlated with the attachment coefficient of the target wheel when the target wheel is in the recovering negative torque state.

It should be appreciated that the one-dimensional curves determined based on the attachment coefficient of the target wheel may be regarded as a steady compensation torque gradient table corresponding to the target axle, and as an example, the one-dimensional curves and may be regarded as steady compensation torque gradient tables corresponding to the driving positive torque state and the recovering negative torque state of the front wheel, respectively, in the embodiment of the present application, and the steady compensation torque gradient table may be obtained through real vehicle debugging.

The principle of determination of the stability compensation torque gradient table may be the same as that of the one-dimensional curve and will not be explained here.

According to the method of the above embodiment, the stability compensation torque gradient table is obtained according to a predetermined rule, so that the stability compensation torque gradient corresponding to the current state of the target wheel can be selected to obtain the stability compensation torque.

The following are examples of the apparatus of the present application that may be used to perform the method embodiments of the present application. For details not disclosed in the embodiments of the apparatus of the present application, please refer to the embodiments of the method of the present application.

Fig. 2 is a schematic diagram of a vehicle torque control device according to an embodiment of the present application. As shown in fig. 2, the control device of the vehicle torque includes:

A first determination module 201 configured to determine a drive recovery torque boundary of the target shaft based on the friction circle boundary during running of the vehicle;

a second determination module 202 configured to determine a torque variation gradient boundary of the target axle based on the road surface attachment coefficient of the target axle and the longitudinal reference vehicle speed;

an activation module 203 configured to obtain a smoothness function activation parameter of the target shaft, and activate the smoothness function of the target shaft if the smoothness function activation parameter meets a preset smoothness function activation condition;

The request torque limiting module 204 is configured to limit the original request torque of the target shaft by using the drive recovery torque boundary, the original request torque, the drive recovery torque limiting offset coefficient and the target compensation torque after the ride comfort function is activated, so as to obtain a request torque value of the target shaft;

A torque gradient limiting module 205 configured to limit an original torque gradient of the target shaft using the torque gradient boundary and the original demand torque gradient to obtain a torque gradient of the target shaft;

the control module 206 is configured to send the requested torque value and the torque change gradient to the target axle motor and to perform corresponding torque control.

In some embodiments, the first determining module 201 is specifically configured to calculate, when the target axle is in a driving positive torque state, a maximum limit value of a longitudinal driving torque of the target axle by using a maximum adhesion force of left and right wheels of the target axle, a target axle load, a lateral acceleration, and a target wheel radius; when the target axle is in the recovery negative torque state, the longitudinal recovery torque minimum limit value of the target axle is calculated by using the maximum adhesive force of the left wheel and the right wheel of the target axle, the target axle load, the transverse acceleration and the target wheel radius.

In some embodiments, the activation module 203 is specifically configured to activate the ride function if the ride function activation parameter simultaneously satisfies that the longitudinal reference vehicle speed is lower than the preset vehicle speed, the target axle minimum road surface adhesion coefficient is lower than the preset coefficient, the target axle original required torque does not belong to the driving recovery torque boundary range and the target axle original required torque gradient does not belong to the torque variation gradient boundary range.

In some embodiments, the requested torque limit module 204 is specifically configured to obtain a current state of the target wheel; if the current state of the target wheel is an unstable state, the stable compensation torque is 0, and the unstable compensation torque is determined based on the acceleration of the target wheel and the slip ratio of the target wheel; if the current state of the target wheel is a stable state, the unstable compensation torque is 0, and the stable compensation torque is determined based on the attachment coefficient of the target wheel.

In some embodiments, the requested torque limit module 204 is specifically configured to calculate an acceleration of the target wheel using the target wheel first wheel speed; calculating the slip rate of the target wheel by using the reference speed of the target wheel and the second wheel speed of the target wheel; determining an unstable compensation torque gradient according to the acceleration and the slip ratio; and obtaining the unstable compensation torque according to the unstable compensation torque initial value and the unstable compensation torque gradient.

In some embodiments, the requested torque limit module 204 is specifically configured to obtain an unsteady compensation torque gradient table according to acceleration and slip ratio; wherein acceleration is positively correlated with an unstable compensation torque gradient, slip ratio is positively correlated with an unstable compensation torque gradient; when the target wheel is in a driving positive torque state, the maximum value of the unstable compensation torque gradient is a preset unstable compensation torque gradient; when the target wheel is in the recovered negative torque state, the minimum value of the unstable compensating torque gradient is a preset unstable compensating torque gradient.

In some embodiments, the request torque limiting module 204 is specifically configured to determine a steady compensation torque gradient based on the target axle left wheel attachment coefficient and the target axle right wheel attachment coefficient; and obtaining the stable compensation torque according to the stable compensation torque initial value and the stable compensation torque gradient.

In some embodiments, the requested torque limit module 204 is specifically configured to obtain a steady compensation torque gradient table based on the target axle left wheel attachment coefficient and the target axle right wheel attachment coefficient; wherein the stability compensation torque gradient is positively correlated with the attachment coefficient of the target wheel when the target wheel is in a driving positive torque state; the stability compensation torque gradient is inversely related to the attachment coefficient of the target wheel when the target wheel is in the recovered negative torque state.

It should be understood that the sequence number of each step in the foregoing embodiment does not mean that the execution sequence of each process should be determined by the function and the internal logic, and should not limit the implementation process of the embodiment of the present application.

Fig. 3 is a schematic diagram of an electronic device 3 according to an embodiment of the present application. As shown in fig. 3, the electronic apparatus 3 of this embodiment includes: a processor 301, a memory 302 and a computer program 303 stored in the memory 302 and executable on the processor 301. The steps of the various method embodiments described above are implemented when the processor 301 executes the computer program 303. Or the processor 301 when executing the computer program 303 performs the functions of the modules/units in the above-described device embodiments.

The electronic device 3 may be an electronic device such as a desktop computer, a notebook computer, a palm computer, or a cloud server. The electronic device 3 may include, but is not limited to, a processor 301 and a memory 302. It will be appreciated by those skilled in the art that fig. 3 is merely an example of the electronic device 3 and is not limiting of the electronic device 3 and may include more or fewer components than shown, or different components.

The processor 301 may be a central processing unit (Central Processing Unit, CPU) or other general purpose processor, digital signal processor (DIGITAL SIGNAL processor, DSP), application SPECIFIC INTEGRATED Circuit (ASIC), field-programmable gate array (field-programmable GATE ARRAY, FPGA) or other programmable logic device, discrete gate or transistor logic device, discrete hardware components, or the like.

The memory 302 may be an internal storage unit of the electronic device 3, for example, a hard disk or a memory of the electronic device 3. The memory 302 may also be an external storage device of the electronic device 3, for example, a plug-in hard disk provided on the electronic device 3, a smart memory card (SMART MEDIA CARD, SMC), a Secure Digital (SD) card, a flash memory card (FLASH CARD), or the like. The memory 302 may also include both internal storage units and external storage devices of the electronic device 3. The memory 302 is used to store computer programs and other programs and data required by the electronic device.

It will be apparent to those skilled in the art that, for convenience and brevity of description, only the above-described division of the functional units and modules is illustrated, and in practical application, the above-described functional distribution may be performed by different functional units and modules according to needs, i.e. the internal structure of the apparatus is divided into different functional units or modules to perform all or part of the above-described functions. The functional units and modules in the embodiment may be integrated in one processing unit, or each unit may exist alone physically, or two or more units may be integrated in one unit, where the integrated units may be implemented in a form of hardware or a form of a software functional unit.

The integrated modules/units may be stored in a storage medium if implemented in the form of software functional units and sold or used as stand-alone products. Based on such understanding, the present application may implement all or part of the flow of the method of the above embodiment, or may be implemented by a computer program to instruct related hardware, and the computer program may be stored in a storage medium, where the computer program, when executed by a processor, may implement the steps of the method embodiments described above. The computer program may comprise computer program code, which may be in source code form, object code form, executable file or in some intermediate form, etc. The computer readable medium may include: any entity or device capable of carrying computer program code, a recording medium, a U disk, a removable hard disk, a magnetic disk, an optical disk, a computer memory, a read-only memory (ROM), a random access memory (Random Access Memory, RAM), an electrical carrier signal, a telecommunications signal, a software distribution medium, and so forth.

The above embodiments are only for illustrating the technical solution of the present application, and are not limiting; although the application has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit and scope of the technical solutions of the embodiments of the present application, and are intended to be included in the scope of the present application.

Claims (10)

1. A control method of vehicle torque, characterized by comprising:

Determining a driving recovery torque boundary of a target shaft based on the friction circle boundary in the running process of the vehicle;

Determining a torque variation gradient boundary of the target shaft based on a road surface attachment coefficient of the target shaft and a longitudinal reference vehicle speed;

Acquiring a smoothness function activation parameter of the target shaft, and activating the smoothness function of the target shaft if the smoothness function activation parameter meets a preset smoothness function activation condition;

After the ride comfort function is activated, limiting the original request torque of the target shaft by using the drive recovery torque boundary, the original required torque, the drive recovery torque limiting offset coefficient and the target compensation torque to obtain a request torque value of the target shaft;

Limiting the original torque variation gradient of the target shaft by utilizing the torque variation gradient boundary and the original required torque gradient to obtain the torque variation gradient of the target shaft;

and sending the request torque value and the torque change gradient to a target shaft motor and performing corresponding torque control.

2. The method of claim 1, wherein the drive recovery torque boundary comprises a longitudinal drive torque maximum limit and a longitudinal recovery torque minimum limit; the determining a drive recovery torque boundary for a target shaft based on the friction circle boundary includes:

When the target axle is in a driving positive torque state, calculating to obtain a longitudinal driving torque maximum limit value of the target axle by using the maximum adhesive force of left and right wheels of the target axle, the target axle load, the transverse acceleration and the target wheel radius;

And when the target axle is in a recovery negative torque state, calculating to obtain a longitudinal recovery torque minimum limit value of the target axle by using the maximum adhesive force of left and right wheels of the target axle, the target axle load, the transverse acceleration and the target wheel radius.

3. The method of claim 1, wherein activating the ride comfort function of the target shaft if the ride comfort function activation parameter meets a preset ride comfort function activation condition comprises:

And if the smoothness function activation parameter simultaneously meets the condition that the longitudinal reference vehicle speed is lower than the preset vehicle speed, the minimum road surface attachment coefficient of the target shaft is smaller than the preset coefficient, and the original required torque of the target shaft does not belong to the driving recovery torque boundary range and the original required torque gradient of the target shaft does not belong to the torque change gradient boundary range, activating the smoothness function.

4. The method of claim 1, wherein the target compensation torque comprises an unstable compensation torque and a stable compensation torque, and wherein limiting the original requested torque of the target shaft to a requested torque value of the target shaft prior to said utilizing the drive recovery torque boundary, the original demand torque, the drive recovery torque limit offset coefficient, and the target compensation torque further comprises:

Acquiring the current state of a target wheel;

If the current state of the target wheel is an unstable state, the stable compensation torque is 0, and the unstable compensation torque is determined based on the acceleration of the target wheel and the slip rate of the target wheel;

And if the current state of the target wheel is a stable state, the unstable compensation torque is 0, and the stable compensation torque is determined based on the attachment coefficient of the target wheel.

5. The method of claim 4, wherein if the current state of the target wheel is an unstable state, the stability compensation torque is 0, and determining the unstable compensation torque based on the acceleration of the target wheel and the slip ratio of the target wheel comprises:

calculating the acceleration of a target wheel by using the first wheel speed of the target wheel;

calculating the slip rate of the target wheel by using the reference speed of the target wheel and the second wheel speed of the target wheel;

Determining an unstable compensation torque gradient according to the acceleration and the slip ratio;

And obtaining the unstable compensation torque according to the initial value of the unstable compensation torque and the unstable compensation torque gradient.

6. The method of claim 5, further comprising, prior to said determining an unsteady compensating torque gradient based on said acceleration and said slip ratio:

Obtaining an unstable compensation torque gradient table according to the acceleration and the slip ratio;

Wherein the acceleration is positively correlated with the unsteady compensating torque gradient and the slip ratio is positively correlated with the unsteady compensating torque gradient;

when the target wheel is in a driving positive torque state, the maximum value of the unstable compensation torque gradient is a preset unstable compensation torque gradient;

And when the target wheel is in a recovery negative torque state, the minimum value of the unstable compensation torque gradient is the preset unstable compensation torque gradient.

7. The method of claim 4, wherein the target wheel attachment coefficient includes a target axle left wheel attachment coefficient and a target axle right wheel attachment coefficient, wherein the unstable compensation torque is 0 if the target wheel current state is a steady state, and wherein determining the steady compensation torque based on the target wheel attachment coefficient comprises:

Determining a steady compensation torque gradient based on the target axle left wheel attachment coefficient and the target axle right wheel attachment coefficient;

And obtaining the stable compensation torque according to the stable compensation torque initial value and the stable compensation torque gradient.

8. The method of claim 7, further comprising, prior to said determining a stability compensation torque gradient based on said target axle left wheel attachment coefficient and target axle right wheel attachment coefficient:

obtaining a stable compensation torque gradient table according to the target axle left wheel attachment coefficient and the target axle right wheel attachment coefficient;

Wherein the stability compensation torque gradient is positively correlated with an adhesion coefficient of the target wheel when the target wheel is in a driving positive torque state;

the stability compensation torque gradient is inversely related to an adhesion coefficient of the target wheel when the target wheel is in a recuperation negative torque state.

9. A control device for vehicle torque, characterized by comprising:

A first determination module configured to determine a drive recovery torque boundary of the target shaft based on the friction circle boundary during running of the vehicle;

a second determination module configured to determine a torque variation gradient boundary of the target shaft based on a road surface attachment coefficient of the target shaft and a longitudinal reference vehicle speed;

The activating module is configured to acquire the smoothness function activating parameters of the target shaft, and activate the smoothness function of the target shaft if the smoothness function activating parameters meet preset smoothness function activating conditions;

the request torque limiting module is configured to limit the original request torque of the target shaft by using the drive recovery torque boundary, the original required torque, the drive recovery torque limiting offset coefficient and the target compensation torque after the smoothness function is activated, so as to obtain a request torque value of the target shaft;

a torque gradient limiting module configured to limit an original torque gradient of the target shaft using the torque gradient boundary and the original demand torque gradient to obtain a torque gradient of the target shaft;

And a control module configured to send the requested torque value and the torque variation gradient to a target shaft motor and perform corresponding torque control.

10. A storage medium storing a computer program, which when executed by a processor performs the steps of the method according to any one of claims 1 to 8.