CN117885731A

CN117885731A - Hill assist unit and hill assist method for vehicle

Info

Publication number: CN117885731A
Application number: CN202410302866.1A
Authority: CN
Inventors: 刘强; 郭宇亮; 杨军
Original assignee: Bosch Automotive Products Suzhou Co Ltd
Current assignee: Bosch Automotive Products Suzhou Co Ltd
Priority date: 2024-03-18
Filing date: 2024-03-18
Publication date: 2024-04-16

Abstract

The invention provides a hill assist unit and a hill assist method for a vehicle. The hill-hold unit includes a status management module and a hill-hold module. The state management module is configured to: and judging whether the current state of the vehicle and the gradient value of the ramp where the vehicle is located meet the starting condition of the hill-holding auxiliary function, and setting the state of the hill-holding auxiliary function to be an opening state when judging that the starting condition of the hill-holding auxiliary function is met. The hill-holding assistance module is configured to: after the hill-holding assistance function is turned on, the vehicle is caused to be parked on the hill in conjunction with control of at least two of the braking system, the driving system, and the electronic parking brake system of the vehicle.

Description

Hill assist unit and hill assist method for vehicle

Technical Field

The present invention relates generally to the field of vehicle control. In particular, the present invention relates to a hill assist unit and a hill assist method for a vehicle.

Background

Controlling the behavior of a vehicle on a grade is a hotspot problem in the field of vehicle control technology. The existing hill-hold solution can assist the vehicle to rest on the hill or assist the vehicle to start on the hill to a certain extent. However, in the event of an emergency or under severe conditions, such as a braking failure of the vehicle, a towing of the vehicle or a large gradient, the existing hill-assist solution still does not perform well, because of the problem of sliding down the hill or instability of the vehicle on the hill.

Disclosure of Invention

Against this background, the present invention aims to provide a hill-hold solution for a vehicle that enables reliable and efficient hill-hold by combining control of at least two of the vehicle's brake system, drive system and electronic parking brake system (EPB system).

According to one aspect of the present invention, a hill assist unit for a vehicle is provided. The hill-hold unit includes a status management module and a hill-hold module. The state management module is configured to: judging whether the current state of the vehicle and the gradient of the ramp where the vehicle is located meet the starting condition of the parking auxiliary function or not; and setting the hill-holding auxiliary function to an on state when the on condition of the hill-holding auxiliary function is judged to be met. The hill-holding assistance module is configured to: after the hill-holding assistance function is turned on, the vehicle is held on the hill in conjunction with control of at least two of a brake system, a drive system, and an Electronic Parking Brake (EPB) system of the vehicle. The step of judging whether the current state of the vehicle and the gradient value of the ramp where the vehicle is located meet the starting condition of the parking auxiliary function comprises the following steps: when the judging results of the following three judging steps are affirmative, judging that the starting condition of the hill-holding auxiliary function is met; and when at least one of the following three judging results is negative, judging that the starting condition of the hill-holding auxiliary function is not satisfied: judging whether at least two of a brake system, a driving system and an EPB system of the vehicle are valid; judging whether the gradient value of the ramp where the vehicle is located is larger than a gradient threshold value or not; and determining whether a hill-holding assistance request signal is received, wherein the hill-holding assistance request signal is generated based on an autonomous driving function of the vehicle, an assisted driving function, or a hill-holding assistance request of a driver of the vehicle.

According to another aspect of the present invention, a hill-assist method for a vehicle is provided. The method comprises the following steps: judging whether the current state of the vehicle and the gradient value of the ramp where the vehicle is located meet the starting condition of the parking auxiliary function or not; setting the state of the hill-holding auxiliary function to an on state when the on condition of the hill-holding auxiliary function is judged to be met; and after the hill-holding assist function is turned on, controlling at least two of a brake system, a drive system, and an EPB system of the vehicle is combined to cause the vehicle to be held on the hill. The step of judging whether the current state of the vehicle and the gradient value of the ramp where the vehicle is located meet the starting condition of the parking auxiliary function comprises the following steps: when the judging results of the following three judging steps are affirmative, judging that the starting condition of the hill-holding auxiliary function is met; and when at least one of the following three judging results is negative, judging that the starting condition of the hill-holding auxiliary function is not satisfied: judging whether at least two of a brake system, a driving system and an EPB system of the vehicle are valid; judging whether the gradient value of the ramp where the vehicle is located is larger than a gradient threshold value or not; and determining whether a hill-holding assistance request signal is received, wherein the hill-holding assistance request signal is generated based on an autonomous driving function of the vehicle, an assisted driving function, or a hill-holding assistance request of a driver of the vehicle.

According to yet another aspect of the present invention, a machine-readable storage medium storing executable instructions is provided. The instructions, when executed, cause the one or more processors to perform the ramp assist method as described above.

According to yet another aspect of the present invention, a computer program product is provided that includes computer-executable instructions. The instructions, when executed, cause the one or more processors to perform the ramp assist method as described above.

The foregoing presents a simplified summary of the primary aspects of the invention in order to provide a basic understanding of such aspects. This summary is not intended to describe key or critical elements of all aspects of the invention nor is it intended to limit the scope of any or all aspects of the invention. The purpose of this summary is to present some implementations of these aspects in a simplified form as a prelude to the more detailed description that is presented later.

Drawings

The technical solution of the present invention will be more apparent from the following detailed description with reference to the accompanying drawings. It is to be understood that these drawings are solely for purposes of illustration and are not intended as a definition of the limits of the invention.

FIG. 1 is a schematic block diagram of a hill assist system for a vehicle according to an embodiment of the invention.

Fig. 2 is a flowchart of a hill-assist method for a vehicle according to an embodiment of the present invention.

Detailed Description

Embodiments of the present invention provide a hill-hold solution for a vehicle for assisting the vehicle to park on a hill and also for assisting the vehicle to start on a hill.

The ramp auxiliary technical scheme provided by the embodiment of the invention is suitable for a driver driving mode, an automatic driving mode and an auxiliary driving mode. That is, the ramp assisting technical scheme according to the embodiment of the invention is suitable for full-scene working conditions of intelligent driving (for example, ADAS) and man driving.

According to the ramp auxiliary technical scheme provided by the embodiment of the invention, the method is suitable for a process from ascending to parking on a ramp, is also suitable for a process from descending to parking on a ramp, and is also suitable for a process of ascending and descending of the vehicle.

According to the ramp assist technical scheme provided by the embodiment of the invention, in the event that one of a brake system, a driving system and an EPB system of the vehicle fails, a corresponding ramp assist strategy is provided for coping with the failure, so that the vehicle is reliably parked on a ramp.

In an embodiment of the invention, a "failure" of a brake system, drive system or EPB system of a vehicle means: the braking system, the driving system or the EPB system of the vehicle cannot provide the function of the system in normal operation. The causes of the system failure may include one or more of the following: a power failure of the system, a control failure of the system, a communication failure internal to the system or external to the system.

In an embodiment of the invention, the brake system, drive system or EPB system "active" of the vehicle means: the braking system, the driving system or the EPB system of the vehicle can provide the function of the system in normal operation.

In the following, embodiments of the invention are described with reference to the accompanying drawings.

Exemplary System

Fig. 1 shows a hill-assist system 100 for a vehicle according to an embodiment of the invention, which includes a sensor unit 10, a hill-assist unit 20, and an execution unit 30. The hill-assist system 100 is provided on the vehicle, so the hill-assist system 100 is an on-vehicle system.

The sensor unit 10 includes a variety of sensors for sensing a variety of parameters that are required to be used in implementing a hill-assist process according to an embodiment of the invention. The plurality of parameters include, for example, parameters for determining (calculating) the behavior of the vehicle on the ramp: acceleration of the vehicle in a direction parallel to the ramp surface, and speed of the vehicle in a direction parallel to the ramp surface. The plurality of parameters further include, for example, a parameter for determining whether overcurrent or overtemperature occurs: the current flowing through the drive motor of the drive system, the temperature of the drive motor, the current flowing through the solenoid valve of the brake system, and the temperature of the solenoid valve.

The hill-assist unit 20 is capable of separately deciding on the corresponding hill-assist strategy for various scenarios so that the vehicle can reliably park on the hill in various scenarios. The hill-assist unit 20 is also capable of deciding on a strategy for assisting in hill-start of the vehicle.

In one embodiment, the hill-hold unit 20 includes a status management module 21, a hill-hold assist module 22, and a launch assist module 23. It will be appreciated that the naming of these modules is functional and is not intended to limit their implementation or physical location. For example, the modules may be implemented on the same chip or circuit, or may be implemented on different chips or circuits. In addition, these modules may be further divided into a plurality of sub-modules or combined into a single module based on functions.

In one embodiment, the ramp assist unit 20 and its various modules may be implemented in hardware or software or a combination of software and hardware. For portions implemented in hardware, it may be implemented in one or more Application Specific Integrated Circuits (ASICs), digital Signal Processors (DSPs), data Signal Processing Devices (DSPDs), programmable Logic Devices (PLDs), field Programmable Gate Arrays (FPGAs), processors, controllers, micro-controllers, microprocessors, electronic units designed to perform their functions, or a combination thereof. For portions implemented in software, they may be implemented by means of microcode, program code or code segments, which may also be stored in a machine-readable storage medium, such as a storage component.

In one embodiment, the hill assist unit 20 is provided in an Electronic Control Unit (ECU) of the vehicle, in a body controller (VCU) of the vehicle, or in a domain controller of the vehicle.

The execution unit 30 is communicatively coupled to the hill-assist unit 20 for executing a hill-assist strategy that is prescribed by the hill-assist unit 20. The execution unit 30 includes, for example, a brake system 31, a drive system 32, and an EPB system 33 of the vehicle, for executing the decided brake operation, drive operation, and EPB operation, respectively.

Exemplary method

Fig. 2 illustrates a hill-assist method 200 for a vehicle in accordance with an embodiment of the invention. The method 200 may be performed by the hill-assist unit 20 described above or the hill-assist system 100 described above. The method 200 will now be described with reference to the above-described hill-assist unit 20 executing the method 200.

Referring to FIG. 2, at block 210, the state management module 21 determines whether the current state of the vehicle and the grade value of the ramp on which the vehicle is located satisfy the on condition of the park assist function. In one embodiment, the on condition of the hill-holding assistance function includes: 1) At least two of the brake system, the drive system, and the EPB system of the vehicle are active (i.e., the hill-holding assist function is only enabled when two or all three of the brake system, the drive system, and the EPB system are active); 2) The gradient value of the ramp where the vehicle is located is larger than the gradient threshold value; 3) The state management module 21 receives the hill-holding assistance request signal.

In this embodiment, the state management module 21 judges that: 1) Whether at least two of the brake system, the drive system, and the EPB system of the vehicle are active; 2) Whether the gradient value of the ramp on which the vehicle is positioned is larger than a gradient threshold value or not; 3) Whether a hill-holding assistance request signal is received. When the determination results of the above three determinations are affirmative, the state management module 21 determines that the on condition of the hill-holding auxiliary function is satisfied. When at least one of the above three judgment results is negative, the state management module 21 judges that the on condition of the hill-holding auxiliary function is not satisfied.

In one embodiment, the hill-holding assistance request signal may come from an autonomous driving function of the vehicle (e.g., an autonomous driving function requests to invoke/turn on the hill-holding assistance function according to an embodiment of the present invention by the request signal), an assisted driving function (e.g., an assisted driving function requests to invoke/turn on the hill-holding assistance function according to an embodiment of the present invention by the request signal), or a hill-holding assistance request of the vehicle driver (e.g., the vehicle driver inputs a request to turn on the hill-holding assistance function according to an embodiment of the present invention by the human-machine interface of the vehicle, and the human-machine interface sends a request signal containing the request to the state management module 21).

In one embodiment, the grade threshold has an initial value, and the initial value may be preset in the state management module 21. The initial value may be predetermined based on a hill-holding condition when the vehicle is empty and there is no trailer. For example, by real vehicle experiments and/or model calculations, a gradient value with reliable (robust) hill holding performance when the vehicle is empty and there is no trailer is determined as the initial value. The state management module 21 may set the grade threshold to the initial value and adjust based on the initial value based on the actual load situation of the vehicle and the actual trailer situation. For example, the state management module 21 judges: 1) Whether the load of the vehicle is greater than a load threshold; 2) Whether the vehicle is towing a trailer. In the case where at least one of the judgment results of the two judgments is affirmative, the state management module 21 decreases the gradient threshold value. In the case where the determination results of both determinations are negative, the state management module 21 does not adjust the gradient threshold value, that is, the gradient threshold value is the initial value at this time.

Setting the gradient threshold in this way is advantageous because the hill holding capacity is greater when the vehicle load is lighter. The hill holding energy is relatively weak when the vehicle is heavy or the trailer is towed. At this time, the hill-holding assist function is turned on a small gradient, and it is possible to ensure that the vehicle is reliably held on the hill.

Notably, in embodiments of the invention, the load of the vehicle includes the man and load of the vehicle, but does not include the trailer towed by the vehicle. In an embodiment of the invention, the situation where the vehicle is towing the trailer is taken as a situation independent of the vehicle load. That is, in adjusting the grade threshold, the load situation and the trailer situation of the vehicle are considered, respectively.

For example, the state management module 21 may determine whether the vehicle is towing a trailer based on the trailer signal and decrease the grade threshold when it is determined that the vehicle is towing a trailer. The trailer signal may comprise a binary signal, with the trailer signal being a "1" when the vehicle is towing the trailer and a "0" when the vehicle is not towing the trailer. The trailer signal may also include a trailer type signal (which includes information indicative of the type of trailer) and a trailer weight signal (which includes information indicative of the weight of the trailer). The status management module 21 determines the degree of reduction in the grade threshold based on the trailer type signal and the trailer weight signal. A table (lookup table) containing the trailer type and the correspondence between the trailer weight and the degree of gradient threshold reduction may be stored in advance in the state management module 21. The status management module 21 inputs the trailer type signal and the trailer weight signal into the look-up table and obtains from the look-up table the degree of reduction in the grade threshold (the degree of reduction may be expressed in terms of a percentage, for example, -5%).

For example, the state management module 21 may determine a man count of the vehicle based on a seating signal (which may be measured by a pressure sensor under the vehicle seat) and decrease the grade threshold when it is determined that the man count of the vehicle exceeds the man count threshold. This example is particularly applicable where the vehicle is a passenger car or a bus. The status management module 21 may determine whether the cargo weight of the vehicle is greater than a cargo weight threshold based on the cargo weight signal (which may be obtained based on the cargo weight data of the vehicle). Upon determining that the cargo weight of the vehicle is greater than the cargo weight threshold, the state management module 21 decreases the grade threshold. This example is particularly applicable where the vehicle is a truck or van.

Notably, such a situation may occur: the vehicle is towing the trailer and the load of the vehicle is greater than the load threshold (e.g., the number of people exceeds the number of people threshold or the weight of the load exceeds the weight of the load threshold). In this case, the gradient threshold value may be reduced to a predetermined lower limit value of the gradient threshold value. The predetermined lower limit value may be predetermined based on real vehicle testing and/or model calculations and stored in the state management module 21.

Each of the brake system, the drive system, and the EPB system may send a validity signal to the vehicle bus indicating whether it is valid. The status management module 21 determines whether each system is valid based on the validity signal. It should be noted that the present invention is not limited to a particular implementation of determining whether each of the brake system, the drive system, and the EPB system is active.

According to an embodiment of the invention, the default state of the hill-holding assistance function is off. When the state management module 21 determines that the on condition of the hill-holding assistance function is not satisfied, the method 200 does not enter the subsequent flow, and continues to perform the determination in block 210.

When the state management module 21 determines that the on condition of the hill-holding auxiliary function is satisfied, the default off state of the hill-holding auxiliary function is switched to the on state, and the method 200 proceeds to block 220.

At block 220, the hill-holding assistance module 22 combines control of at least two of the vehicle's braking system, drive system, and EPB system to cause the vehicle to be held on the hill. Some implementations of block 220 are described below (see blocks 221-224), respectively.

First hill-holding assistance strategy

At block 221, when the state management module 21 determines that the braking system is disabled and both the drive system and the EPB system are active, the hill-holding assistance module 22 determines a first hill-holding assistance strategy for the case where the braking system is disabled and both the drive system and the EPB system are active.

The first hill-holding assistance strategy includes: a target total driving force of the vehicle is determined, and the target total driving force is distributed into a front axle target driving force and a rear axle target driving force based on vertical load transfer of front and rear axles of the vehicle.

In one embodiment, the hill-holding assistance module 22 may determine the target total driving force as follows. When the vehicle starts to stop on the slope, the hill-holding assistance module 22 determines an initial value of the target total driving force based on the target deceleration when the vehicle starts to stop on the slope. The target deceleration may be determined based on the operation force of the brake pedal by the driver, or may be determined by a driving assist function or an automatic driving function. During a vehicle braking on a grade, the hill-holding assistance module 22 aims to ensure a smooth transition of the vehicle speed to zero (i.e., from the vehicle speed at the time of starting the vehicle braking to zero), and adjusts on the basis of an initial value of the target total driving force until the vehicle is stopped on the grade. At this time, the value of the target total driving force is the final value of the target total driving force. In this embodiment, the adjusting step may be implemented by means of a predetermined vehicle speed change rate curve. The adjusting step may also be implemented by presetting a maximum value and a minimum value of the rate of change of the vehicle speed and making the rate of change of the vehicle speed always between the maximum value and the minimum value. The final value of the target total driving force thus determined is the target driving force that causes the vehicle to park on the slope.

In another embodiment, the hill-holding assistance module 22 may determine the target total driving force as follows. The ramp resistance when the vehicle is empty and there is no trailer can be obtained by the following equation (1):

wherein the method comprises the steps of，A component of gravitational acceleration in the direction of the ramp (i.e., in a direction parallel to the ramp);for the mass of the vehicle when empty, < > is given>The vehicle is unloaded and there is no ramp resistance of the trailer.

The target total driving force of the vehicle can be such that the vehicle just parks on the hill, i.e. can be against a force value based on the actual mass situation of the vehicle and the hill resistance of the actual trailer situation. The target driving force of the vehicle can be obtained by adjusting the actual mass situation of the vehicle and the actual trailer situation on the basis of the ramp resistance when the vehicle is empty and no trailer exists. For example, the adjustment may be performed by table look-up, model calculation, or preset correction factors. In addition, the adjustment according to the embodiment of the invention takes into consideration special situations such as rainy and snowy weather or wet road surface. In such a special case, the target total driving force may be adjusted again according to the adjustment amount preset for the special case.

In one embodiment, the hill-holding assistance module 22 may calculate the vertical load transfer of the front and rear axles of the vehicle, as well as the front axle target driving force and the rear axle target driving force, by the following formulas (2) - (7).

When the vehicle is parked on a slope from an ascending slope, the vertical load of the front and rear axles can be calculated by the following equations (2) and (3):

when the vehicle is parked on a slope from downhill, the vertical load of the front and rear axles can be calculated by the following equations (4) and (5):

wherein alpha is the gradient of the ramp on which the vehicle is positioned; g is the weight of the vehicle when empty (which can be obtained by multiplying the mass of the vehicle when empty by the acceleration of gravity); a is the distance from the mass center to the front axle; b is the distance from the mass center to the rear axle; l is the wheelbase; hg is the centroid height of the vehicle;is the vertical load of the front axle; />Is the vertical load of the rear axle.

The front axle target driving force and the rear axle target driving force can be obtained by the following formulas (6) and (7):

wherein,is the target total driving force; f1 is the target driving force of the front axle; f2 is the target driving force of the rear axle.

It is noted that the target total driving force is a target total forward driving force (forward refers to the same direction as the vehicle traveling direction) when the vehicle is traveling from an uphill to a standstill on a hill (i.e., the vehicle is traveling from an uphill to a standstill). And, the target driving force of the front axle is the forward target driving force of the front axle; the target driving force of the rear axle is the target forward driving force of the rear axle. When the vehicle is traveling from downhill to parked on a slope (i.e., the vehicle is traveling from downhill to stationary), the target total driving force is a target total reverse driving force (reverse refers to a direction opposite to the traveling direction of the vehicle). And, the target driving force of the front axle is a reverse target driving force of the front axle; the target driving force of the rear axle is the target reverse driving force of the rear axle.

The first hill-holding assistance strategy further comprises: when the driving motor of the driving system is over-current or overheated or is about to be over-current or overheated, the EPB system is started, and the target total driving force is reduced. Whether the drive motor is over-current may be determined by whether the current flowing through the drive motor is greater than an over-current threshold. Whether the driving motor is overheated or not may be determined by whether the temperature of the driving motor is greater than a preset temperature threshold. In the case where the drive system includes a plurality of drive motors (e.g., a front-axle drive motor and a rear-axle drive motor), one of the plurality of drive motors is over-flowed or overheated, the drive motor of the drive system is considered to be over-flowed or overheated. According to embodiments of the present invention, the occurrence of an overcurrent or overheat may be achieved by reducing the corresponding overcurrent threshold or temperature threshold.

The first hill-holding assistance strategy further comprises: and when the maximum driving force which can be provided by the driving system is smaller than the determined target total driving force, starting the EPB system and reducing the target total driving force.

With the EPB system on, the target total braking force is reduced to zero if only the braking capability provided by the EPB is sufficient to counter the actual ramp resistance (i.e., the current ramp resistance, which is related to the actual mass situation of the vehicle, the actual trailer situation, and the current adhesion coefficient of the ramp surface), i.e., the braking force provided by the EPB system is greater than or equal to the actual ramp resistance. At this time, the driving motor does not need to work, and the motor current is zero. If the braking capability provided by the EPB alone is insufficient to counter the actual hill resistance, i.e., the braking force provided by the EPB system is less than the actual hill resistance, the resultant of the reduced target total driving force and the braking force provided by the EPB system is enabled to cause the vehicle to park on the hill. At this time, the front axle drive motor and the rear axle drive motor may be controlled to alternately operate so that the front axle drive motor and the rear axle drive motor alternately achieve the reduced target total driving force, or the reduced target total driving force may be distributed into the front axle target driving force and the rear axle target driving force in accordance with the vertical load transfer of the front and rear axles. Thereby, the operable period of the drive system can be prolonged.

Second hill-holding assistance strategy

At block 222, when the state management module 21 determines that the drive system is disabled and that both the brake system and the EPB system are active, the hill-holding assistance module 22 determines a second hill-holding assistance strategy for the case where the drive system is disabled and both the brake system and the EPB system are active.

The second hill-holding assistance strategy comprises: a target total braking force of the vehicle is determined, and the target total braking force is distributed into a front axle target braking force and a rear axle target braking force based on vertical load transfer of front and rear axles of the vehicle.

In one embodiment, the hill-holding assistance module 22 determines the target total braking force based on the hill resistance of the vehicle when the vehicle is empty and there is no trailer, the actual load situation of the vehicle, and the actual trailer situation.

The ramp resistance when the vehicle is empty and there is no trailer can be obtained by the above formula (1), and is not described here.

The target total braking force of the vehicle can be such that the vehicle just parks on the hill, i.e. can be against a force value based on the actual mass situation of the vehicle and the hill resistance of the actual trailer situation. The target total braking force of the vehicle can be obtained by adjusting the actual mass situation of the vehicle and the actual trailer situation on the basis of the ramp resistance when the vehicle is empty and no trailer exists. For example, the adjustment may be performed by table look-up, model calculation, or preset correction factors. In addition, according to embodiments of the present invention, the factor of the adhesion coefficient of the ramp surface is also considered. For example, special cases may occur in which rain and snow weather or slippery road surface or the like causes a change in the attachment coefficient of the ramp surface. In such a special case, the target total braking force may be adjusted again according to the adjustment amount preset for the special case.

The vertical load of the front and rear axles can be calculated by the above formulas (2) and (3) when the vehicle is parked on the slope from an ascending slope. The vertical load of the front and rear axles can be calculated by the above formulas (4) and (5) when the vehicle is parked on the slope from downhill. And are not described in detail herein.

The front axle target braking force and the rear axle target braking force can be obtained by the following formulas (8) and (9):

wherein,is the target total braking force; f11 is the target braking force of the front axle; f22 is the target braking force of the rear axle.

The second hill-holding strategy further comprises: when an overcurrent or overheat occurs or is about to occur in a motor of the brake system or a solenoid valve for controlling a brake cylinder, the EPB system is turned on and the target total braking force is reduced. Whether the motor or solenoid is over-current may be determined by whether the current through the motor or solenoid is greater than an over-current threshold. Whether the motor or the solenoid valve is overheated or not may be determined by whether the temperature of the motor or the temperature of the solenoid valve is greater than a preset temperature threshold. In the case where the braking system includes a plurality of motors or a plurality of solenoid valves, the motor or solenoid valve of the braking system is considered to be over-heated as long as one motor or solenoid valve is over-heated or overheated. The impending overcurrent or overheat may be achieved by lowering the corresponding overcurrent threshold or temperature threshold according to embodiments of the present invention.

The second hill-holding strategy further comprises: when the maximum braking force which can be provided by the braking system is smaller than the determined target total braking force, the EPB system is started, and the target total braking force is reduced.

In the case where the EPB system is on, the target total braking force is reduced to zero if only the braking capability provided by the EPB is sufficient to counter the actual ramp resistance, i.e., the braking force provided by the EPB system is greater than or equal to the actual ramp resistance. If the braking capability provided by the EPB alone is insufficient to counter the actual ramp resistance, i.e., the braking force provided by the EPB system is less than the actual ramp resistance, then the resultant of the reduced target total braking force and the braking force provided by the EPB system is enabled to cause the vehicle to park on the ramp. At this time, the solenoid valves of the wheel cylinders of the respective wheels may be controlled to alternately operate to achieve the reduced target total braking force, or the reduced target total braking force may be distributed into the front axle target braking force and the rear axle target braking force based on the vertical load transfer of the front and rear axles of the vehicle. Thereby, the operable time period of the brake system can be prolonged.

Third hill-holding assistance strategy

At block 223, when the state management module 21 determines that the EPB system is disabled and both the braking system and the driving system are active, the hill-holding assistance module 22 determines a third hill-holding assistance strategy for the case where the EPB system is disabled and both the braking system and the driving system are active.

In one implementation, the third hill-holding assistance strategy includes: the vehicle is preferably parked on a slope by the driving force provided by the driving system, and the braking force provided by the braking system is used as a standby or supplement. For example, during braking and parking of the vehicle, the actual total driving force of the drive system is increased according to a first predetermined slope, and the actual total braking force of the brake system is decreased according to a second predetermined slope, such that: the resultant of the actual total driving force and the actual total braking force enables the vehicle to park on the ramp, and also enables: the maximum value of the actual total driving force is smaller than the ramp resistance when the vehicle is empty and there is no trailer. And the first predetermined slope is greater than the second predetermined slope. In other words, the increase slope of the actual total driving force is larger than the decrease slope of the actual total braking force.

In one embodiment, the resultant of the actual total driving force and the actual total braking force is equal to the braking pressure that causes the vehicle to park on the ramp. Here, the braking pressure at which the vehicle is caused to park on the slope refers to the braking pressure at which the vehicle is caused to park on the slope by means of only the braking pressure without the aid of the driving force.

In one embodiment, the actual total braking force has a predetermined minimum value, i.e. it has a predetermined lower limit value below which it cannot be reduced during the reduction of the actual total braking force. The predetermined minimum value of the actual total braking force is greater than zero, i.e. at least some braking pressure needs to be maintained to assist in hill holding. And, the predetermined minimum value of the actual total braking force is associated with the gradient value of the ramp. For example, the predetermined minimum value increases with an increase in the gradient value. A table containing the correspondence between the minimum value and the gradient value may be prepared in advance, and the minimum value may be obtained by looking up a table.

In another implementation, the third hill-holding assistance strategy includes: the driving system and the braking system work in turn, so that the total driving force provided by the driving system and the total braking force provided by the braking system offset the current ramp resistance in turn, and the working time of the braking system and the driving system is prolonged. For example, in the above manner, the target total driving force and the target total braking force that enable the vehicle to park on the slope are determined. The drive system and the brake system provide a target total drive force or a target total brake force, respectively, in accordance with a predetermined timing. Thereby, the operable time period of the drive system and the brake system can be prolonged.

Fourth hill-holding assistance strategy

At block 224, when the state management module 21 determines that the EPB system, the brake system, and the drive system are all active, the hill-holding assistance module 22 determines a fourth hill-holding assistance strategy for the case where the EPB system, the brake system, and the drive system are all active. According to a fourth assist strategy of an embodiment of the present invention, control of the drive system and the brake system is combined to assist the vehicle in hill holding without the EPB system being turned on. The control strategy in this case is the same as the third hill-holding assistance strategy described above, and will not be described in detail here.

In the case where the EPB system is turned on, if only the braking capability provided by the EPB is sufficient to counter the actual ramp resistance, i.e., the braking force provided by the EPB system is greater than or equal to the actual ramp resistance, both the target total braking force and the target total driving force are reduced to zero. If the braking capacity provided by the EPB alone is insufficient to counter the actual ramp resistance, i.e. the braking force provided by the EPB system is less than the actual ramp resistance, the driving force provided by the drive system and/or the braking force provided by the braking system is used to compensate.

With respect to this compensation, one implementation is: the resultant force of the driving force provided by the driving system and/or the braking force provided by the braking system to compensate for the braking force provided by the EPB system is used for stopping the vehicle on the slope. At this time, the front shaft driving motor and the rear shaft driving motor can be controlled to alternately operate.

With respect to this compensation, another implementation is: if the wheel coupled to the axle to which the EPB system applies the brake has no wheel speed (the wheel speed is zero), and the wheel coupled to the other axle (i.e., the axle to which the EPB system does not apply the brake has a wheel speed (the wheel speed is not zero) and the wheel speed direction is opposite to the vehicle traveling direction, the driving force or braking force is applied to the axle to which the EBP system does not apply the brake so that the resultant force of the driving force or braking force and the braking force provided by the EPB system causes the vehicle to park on the slope. If the wheels coupled to the axle to which the EPB system applies the brake have wheel speeds (the wheel speeds are not zero) and the wheel speeds are opposite to the vehicle traveling direction, driving force or braking force is applied to both the front and rear axles, and the driving force or braking force of the front and rear axles is distributed in accordance with the vertical load transfer of the front and rear axles so that the resultant force of the driving force or braking force and the braking force provided by the EPB system causes the vehicle to park on the slope.

At block 230, the hill-holding assistance module 22 sends the determined hill-holding assistance strategy to the execution unit 30 so that the execution unit 30 performs the corresponding maneuver, i.e., one or more of the brake maneuver, the drive maneuver, and the EPB maneuver, according to the hill-holding assistance strategy.

In addition, according to an embodiment of the present invention, during execution of the fourth hill-holding assistance strategy by the execution unit 30 (i.e., during the period when the EPB system, the brake system, and the drive system are all active), if a brake system failure occurs, the switching is automatically made to execute the first hill-holding assistance strategy; if the driving system fails, automatically switching to execute a second hill-holding auxiliary strategy; if the EPB system fails, the method automatically switches to execute a third hill-holding assistance strategy.

At block 240, the state management module 21 turns on the hill start assist function in accordance with an embodiment of the present invention after receiving the start request signal. For example, the default state of the hill start assist function is off. After receiving the start request signal, the state management module 21 switches the default off state of the hill start assist function to on. The start request signal may be from an autopilot function of the vehicle (e.g., an autopilot function requests invocation/activation of a hill start assist function according to an embodiment of the invention via a request signal), an assisted drive function (e.g., an assisted drive function requests invocation/activation of a hill start assist function according to an embodiment of the invention via a request signal), or a start request of the vehicle driver (e.g., the vehicle driver inputs a request to activate a hill start assist function according to an embodiment of the invention via a human-machine interface of the vehicle, and the human-machine interface sends a request signal containing the request to the state management module 21).

In block 250, the launch assist module 23 determines an uphill launch assist strategy (block 251) and a downhill launch assist strategy (block 252), respectively, for uphill launch and downhill launch conditions of the vehicle.

In the case where the vehicle is an uphill launch, the uphill launch assist strategy includes: a target total start driving force enabling smooth start of the vehicle is determined, and the target total start driving force is distributed into a target driving force of the front axle and a target driving force of the rear axle in accordance with vertical load transfer of the front and rear axles.

In the case where the vehicle is a hill start, the hill start strategy includes, at block 252: a target counter moment is determined for ensuring that a downhill launch acceleration of the vehicle is less than a launch acceleration threshold. And the target reverse moment is realized by preferentially utilizing the reverse moment obtained by energy recovery of the driving system, and when the reverse moment obtained by energy recovery is insufficient to realize the target reverse moment, the provided reverse moment of the driving system is adopted for supplementing. Therefore, the vehicle body movement possibly generated when the vehicle starts downhill can be restrained, and the smoothness of the downhill starting of the vehicle is improved.

At block 260, the launch assist module 23 sends the determined hill start assist strategy to the execution unit 30 so that the execution unit performs the corresponding maneuver according to the hill start assist strategy.

Embodiments of the invention also provide a machine-readable storage medium storing executable instructions that when executed cause one or more processors to perform the hill-assist method 200 as described above.

Embodiments of the present invention also provide a computer program product comprising computer-executable instructions that, when executed, cause one or more processors to perform the hill-hold method 200 as described above.

It should be understood that all operations in the methods described above are merely exemplary, and the present disclosure is not limited to any operations in the methods or to the order of such operations, but rather should cover all other equivalent variations under the same or similar concepts.

It should be appreciated that the processor may use any combination of one or more of the following: suitable central processing units, CPUs, multiprocessors, single chip microcomputer, digital signal processors, DSPs, application specific integrated circuits, etc. are capable of executing software instructions of a computer program stored in a memory. Thus, the memory may be considered as part of or form part of a computer program product. The processor may be configured to execute a computer program stored therein to cause the controller to perform the required steps.

It should be understood that an article of manufacture is intended to refer broadly to an instruction, set of instructions, code segments, program code, programs, subroutines, software modules, applications, software packages, routines, subroutines, objects, threads of operation, procedures, functions, and the like. The software may reside in a computer readable medium. Computer-readable media may include, for example, memory, which may be, for example, a magnetic storage device (e.g., hard disk, floppy disk, magnetic strips), optical disk, smart card, flash memory device, random Access Memory (RAM), read-only memory (ROM), programmable ROM (PROM), erasable PROM (EPROM), electrically Erasable PROM (EEPROM), registers, or removable disk. Although the memory is shown separate from the processor in various aspects presented in this disclosure, the memory may also be located internal to the processor (e.g., in a cache or register).

The previous description is provided to enable any person skilled in the art to practice the various aspects described herein. Various modifications to these aspects will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other aspects. Accordingly, the claims are not intended to be limited to the aspects shown herein. All structural and functional equivalents to the elements of the various aspects described herein that are known or later come to be known to those of ordinary skill in the art are expressly incorporated herein by reference and are intended to be encompassed by the claims.

Claims

1. A hill-assist unit for a vehicle includes a status management module and a hill-holding assist module,

the state management module is configured to: judging whether the current state of the vehicle and the gradient of the ramp where the vehicle is located meet the starting condition of the parking auxiliary function or not; setting the state of the hill-holding auxiliary function to an on state when the on condition of the hill-holding auxiliary function is judged to be met; and is also provided with

The hill-holding assistance module is configured to: after the hill-holding assistance function is activated, the vehicle is caused to be parked on the hill in conjunction with control of at least two of a braking system, a driving system, and an Electronic Parking Brake (EPB) system of the vehicle,

the step of judging whether the current state of the vehicle and the gradient of the ramp where the vehicle is located meet the starting condition of the parking auxiliary function comprises the following steps: when the judging results of the following three judging steps are affirmative, judging that the starting condition of the hill-holding auxiliary function is met; and when at least one of the following three judging results is negative, judging that the starting condition of the hill-holding auxiliary function is not satisfied:

judging whether at least two of a brake system, a driving system and an EPB system of the vehicle are valid;

judging whether the gradient value of the ramp where the vehicle is located is larger than a gradient threshold value or not;

A determination is made as to whether a hill-holding assistance request signal is received, wherein the hill-holding assistance request signal is generated based on an autonomous driving function of the vehicle, an assisted driving function, or a hill-holding assistance request of a driver of the vehicle.

2. A hill assist unit as claimed in claim 1, wherein the status management module determines the grade threshold as follows:

setting a grade threshold to a predetermined initial value, wherein the predetermined initial value is predetermined based on a situation in which the vehicle is empty and there is no trailer; and

the adjustment is made on the basis of said predetermined initial value in dependence of the actual load situation of the vehicle and the actual trailer situation.

3. A ramp assist unit according to claim 2, wherein adjusting on the basis of the predetermined initial value in dependence on the actual load situation of the vehicle and the actual trailer situation comprises: adjusting the slope threshold in a decreasing direction based on the initial value upon determining at least one of:

the vehicle is towing the trailer;

the number of people carried by the vehicle is greater than a threshold number of people carried; and

the cargo weight of the vehicle is greater than the cargo weight threshold.

4. A hill assist unit as claimed in any one of claims 1 to 3 wherein the hill-holding assist module is configured to: in the event that the current state of the vehicle is a brake system failure and both the drive system and the EPB system are active, a first hill-holding assistance strategy is determined for that situation,

And wherein the first hill-holding assistance strategy comprises: a target total driving force for causing the vehicle to park on the slope is determined, and the target total driving force is distributed into a front axle target driving force and a rear axle target driving force based on a vertical load transfer of front and rear axles of the vehicle.

5. A hill assist unit as defined in claim 4, wherein the first hill-holding assist strategy further comprises:

when the drive motor of the drive system is or is about to be over-current and/or over-heated, the EPB system is turned on and the target total drive force is reduced.

6. A hill assist unit as claimed in claim 5, wherein reducing the target total driving force comprises:

the target total driving force is reduced to zero when the braking force provided by the EPB system can enable the vehicle to park on the slope; and

when the braking force provided by the EPB system fails to cause the vehicle to park on the slope, the resultant of the reduced target total driving force and the braking force provided by the EPB system is enabled to cause the vehicle to park on the slope,

alternatively, the reduced target total driving force is achieved by alternately operating the front axle drive motor and the rear axle drive motor of the drive system, or the reduced target total driving force is distributed into the front axle target driving force and the rear axle target driving force based on the vertical load transfer of the front and rear axles of the vehicle.

7. A hill assist unit as claimed in any one of claims 1 to 3 wherein the hill-holding assist module is configured to: in the event that the current state of the vehicle is a drive system failure and both the brake system and the EPB system are active, a second hill-holding assistance strategy is determined for that situation,

and wherein the second hill-holding assistance strategy comprises: a target total braking force for causing the vehicle to park on the slope is determined, and the target total braking force is distributed into a front axle target braking force and a rear axle target braking force based on vertical load transfer of front and rear axles of the vehicle.

8. A hill assist unit as defined in claim 7, wherein the second hill-holding assist strategy further comprises:

when the motor of the brake system or the electromagnetic valve for controlling the brake cylinder is over-current or over-temperature or overheat happens, the EPB system is started, and the target total braking force is reduced.

9. A hill assist unit as claimed in claim 8, wherein reducing the target total braking force comprises:

the target total braking force is reduced to zero when the braking force provided by the EPB system can enable the vehicle to park on the ramp; and

when the braking force provided by the EPB system fails to cause the vehicle to park on the slope, the target total braking force is reduced so that the resultant of the reduced target total braking force and the braking force provided by the EPB system can cause the vehicle to park on the slope,

Alternatively, the solenoid valves controlling the wheel cylinders of the respective wheels are alternately operated to achieve the reduced target total braking force, or the reduced target total braking force is distributed into the front axle target braking force and the rear axle target braking force based on the vertical load transfer of the front and rear axles of the vehicle.

10. A hill assist unit as claimed in any one of claims 1 to 3 wherein the hill-holding assist module is configured to: in the event that the current state of the vehicle is that the EPB system is disabled and both the braking system and the driving system are active, a third hill-holding assistance strategy is determined for that situation,

and wherein the third hill-holding assistance strategy comprises: the vehicle is caused to park on the slope by both the driving force provided by the driving system and the braking force provided by the braking system, or alternatively caused to park on the slope by both the driving force provided by the driving system and the braking force provided by the braking system.

11. A hill-assist unit as claimed in claim 10, wherein parking the vehicle on the hill by both the driving force provided by the driving system and the braking force provided by the braking system comprises:

increasing the actual total driving force of the driving system according to a first predetermined slope and decreasing the actual total braking force of the braking system according to a second predetermined slope such that: the resultant of the actual total driving force and the actual total braking force enables the vehicle to be parked on the slope, and enables: the maximum value of the actual total driving force is smaller than the ramp resistance when the vehicle is empty and there is no trailer, wherein the first predetermined slope is larger than the second predetermined slope.

12. A hill assist unit as claimed in claim 11, wherein the resultant force is equal to a brake pressure to cause the vehicle to park on the hill; and is also provided with

Wherein the actual total braking force has a predetermined minimum value, which is greater than zero and which is associated with the gradient value of the ramp.

13. A hill-assist unit as claimed in claim 10, wherein alternately parking the vehicle on the hill by the driving force provided by the driving system and the braking force provided by the braking system comprises:

determining a target total driving force to cause the vehicle to park on the ramp;

determining a target total braking force to cause the vehicle to park on the ramp;

the drive system and the brake system are controlled to alternately operate such that the brake system and the drive system alternately provide a target total driving force and a target total braking force for the vehicle to park on the hill, such that the drive system and the brake system alternately counteract the current hill resistance.

14. A hill-assist unit as claimed in claim 1, further comprising a launch-assist module configured to:

determining a target reverse torque for limiting the starting acceleration of the vehicle to be less than a starting acceleration threshold value under the condition that the vehicle starts downhill; and

The target reverse torque is realized by preferentially utilizing the reverse torque obtained by energy recovery of the driving system, and when the reverse torque obtained by energy recovery is insufficient to realize the target reverse torque, the reverse torque of the driving system is adopted for supplementing.

15. A hill assist method for a vehicle, comprising:

judging whether the current state of the vehicle and the gradient value of the ramp where the vehicle is located meet the starting condition of the parking auxiliary function or not;

setting the state of the hill-holding auxiliary function to an on state when the on condition of the hill-holding auxiliary function is judged to be met; and

after the hill-holding assistance function is turned on, controlling at least two of a brake system, a drive system, and an EPB system of the vehicle is combined to cause the vehicle to be held on the hill;

the step of judging whether the current state of the vehicle and the gradient value of the ramp where the vehicle is located meet the starting condition of the parking auxiliary function comprises the following steps: when the judging results of the following three judging steps are affirmative, judging that the starting condition of the hill-holding auxiliary function is met; and when at least one of the following three judging results is negative, judging that the starting condition of the hill-holding auxiliary function is not satisfied:

16. A machine readable storage medium storing executable instructions that when executed cause one or more processors to perform the hill-assist method of claim 15.

17. A computer program product comprising computer-executable instructions that, when executed, cause one or more processors to perform the hill-assist method of claim 15.