CN112824187B - Driving assistance system, and deceleration control unit and method thereof - Google Patents

Abstract

The invention provides a driving assistance system, a deceleration control unit and a method thereof. The deceleration control unit comprises an acquisition module, a calculation module, a judgment module and a determination module. The acquisition module acquires a deceleration request and travel data of the vehicle. The calculation module calculates a target deceleration of the vehicle in response to the deceleration request, and calculates a target gear ratio such that the vehicle reaches the target deceleration based on a difference between the target deceleration and a current deceleration. The determination module determines a target gear that causes the vehicle to reach the target gear based on a difference between a target gear ratio and a current gear ratio and a gear ratio model, and sends the target gear to an automatic transmission control unit of the vehicle. The gear ratio model is a function that represents a correspondence between gear ratios during a shift and gear positions of the automatic transmission.

Description

Driving assistance system, and deceleration control unit and method thereof

Technical Field

The present invention relates to a driving assistance technique for a vehicle, and more particularly, to a deceleration control unit for a driving assistance system of a vehicle. The invention also relates to a driving assistance system with the deceleration control unit and a related deceleration control method.

Background

It is known that a vehicle is equipped with a driving assistance system. The driving assistance system of the vehicle includes various systems that perform different functions, such as an adaptive cruise control system and a running stability system. The adaptive cruise control system can reduce the burden on the driver in running the vehicle, control the vehicle speed earlier before feeling tired, and run easily and safely behind the vehicle running slower. The running stability system can improve the operability and running stability of the vehicle and expand the running stability range of the vehicle.

According to the existing control strategy of the driving assistance system, when the vehicle needs to be decelerated, the adaptive cruise system electronically activates the running stability system, whereby the running stability system performs braking manipulation to achieve deceleration of the vehicle. When the vehicle needs to be decelerated several times over a longer road section or slowly over a long period of time, a situation may occur in which the stability system frequently performs active braking interventions, which may cause uncomfortable driving experience.

Disclosure of Invention

The present invention aims to provide an improved deceleration control scheme for assisting in driving a vehicle, which is capable of improving driving comfort while achieving a target deceleration.

According to an aspect of the present invention, there is provided a deceleration control unit for a driving assistance system of a vehicle, wherein the vehicle is a vehicle with an automatic transmission, the deceleration control unit including an acquisition module that acquires a deceleration request and running data of the vehicle, the running data including at least a current deceleration and a current gear ratio, a calculation module, a determination module, and a determination module; the calculation module calculates a target deceleration of the vehicle in response to the deceleration request, the judgment module judges whether the target deceleration is equal to or smaller than a deceleration threshold, and if the judgment result is affirmative, the calculation module calculates a target gear ratio for the vehicle to reach the target deceleration based on a difference between the target deceleration and a current deceleration; and the determination module determines a target gear that causes the vehicle to reach the target gear based on a difference between the target gear and a current gear and a gear model, and sends the target gear to an automatic transmission control unit of the vehicle, wherein the gear model is a function that represents a correspondence between gears of the automatic transmission and gear of the gear during a shift.

According to one possible embodiment, the gear ratio model is based on experimentally measured sets of data for gear ratios and gear ranges during shifting, and is obtained by processing the sets of data by at least one of theoretical calculation and curve fitting.

According to one possible embodiment, in the case where the determination result is negative, operations of the calculation module and the determination module are prohibited, and the determination module sends a deceleration request to a running stability system of the vehicle to achieve a target deceleration through brake manipulation.

According to a possible embodiment, the deceleration threshold corresponds to a deceleration value that the automatic transmission lowers by two or more gear steps such that the vehicle achieves.

According to one possible embodiment, the acquisition module acquires a gradient value of a road on which the vehicle is traveling; the judging module judges whether the acquired gradient value is smaller than or equal to a gradient threshold value; allowing operation of the calculation module and the determination module if the judgment result is affirmative; in the case where the determination result is negative, operations of the calculation module and the determination module are prohibited, and the determination module sends a deceleration request to a running stability system of the vehicle to achieve a target deceleration by brake manipulation.

According to one possible embodiment, in case of a potential collision object in front of the vehicle, the calculation module is responsive to a deceleration request and calculates the target deceleration based on a relative speed and a relative distance of the vehicle and the potential collision object; and in the case where there is no potential collision object in front of the vehicle, the calculation unit calculates a target deceleration in response to a deceleration request and based on a set vehicle speed input by the vehicle driver.

According to one possible embodiment, in case of a potential collision object in front of the vehicle, the calculation module calculates the target deceleration in response to a deceleration request based on the following formula: aTar = (V1-V2)/(2/2S), where aTar is the target deceleration, (V1-V2) and S are the relative speed and relative distance between the vehicle and the front potential collision object, respectively; and in the case where there is no potential collision object in front of the vehicle, the calculation unit calculates a target deceleration in response to a deceleration request based on the following formula: aTar = (Vset-V1)/T, where aTar is a target deceleration, vset is a vehicle speed set by a driver of the vehicle, V1 is a vehicle speed of the vehicle, and T is a value set in advance in the driving assistance system.

According to one possible embodiment, the calculating module calculating the target gear ratio based on a difference between a target deceleration and a current deceleration includes: calculating a required increased braking force on wheels of the vehicle to achieve the target deceleration based on the difference, and calculating a required increased torque at the wheels based on the required increased braking force and the wheel radius; calculating a current torque at the wheels based on the current gear ratio and the current engine torque; calculating a target torque at the wheel based on the current torque at the wheel and the torque that needs to be increased; and calculating the target gear ratio based on the target torque at the wheels and the current transmitter torque.

According to a possible embodiment, the deceleration control unit further comprises a recovery module configured to generate a recovery instruction for instructing recovery of kinetic energy of the vehicle during deceleration and converting the kinetic energy into electrical energy for provision to a battery or consumer of the vehicle.

According to another aspect of the present invention, there is provided a driving assistance system for a vehicle, the vehicle being a vehicle with an automatic transmission, the driving assistance system comprising: a forward sensor for sensing travel data of the vehicle; a controller electrically connected with the forward sensor and communicatively connected with an engine management system and a transmission system of the vehicle via a vehicle communication bus, the controller including a deceleration control unit as described above that performs deceleration control in response to a deceleration request and based on data from the forward sensor and data from the engine management system and the transmission system to achieve a target deceleration.

According to a possible embodiment, the forward sensor comprises at least a radar sensor; and the driving assistance system is an adaptive cruise control system or a radar system or a combination of both of the vehicle.

According to a further aspect of the present invention, there is provided a deceleration control method for assisting in driving a vehicle, the vehicle being a vehicle with an automatic transmission, optionally the method being implemented by means of a deceleration control unit as described above and/or a driving assistance system as described above, the method comprising: acquiring a deceleration request and running data of the vehicle, wherein the running data at least comprises current deceleration and current transmission ratio; calculating a target deceleration of the vehicle in response to the deceleration request; judging whether the target deceleration is smaller than or equal to a deceleration threshold value; in the case where the determination result is affirmative, calculating a target gear ratio that causes the vehicle to reach the target deceleration based on a difference between the target deceleration and the current deceleration; determining a target gear for enabling the vehicle to reach the target gear based on a difference value between the target gear and a current gear and a gear ratio model, wherein the gear ratio model is a function which is obtained through at least one of physical experiments, theoretical calculation and simulation fitting and represents a corresponding relation between the gear ratio and the gear of the automatic transmission in a gear shifting process; and transmitting the target gear to an automatic transmission control unit of the vehicle.

According to the technical scheme of the invention, the driving assistance system can send the downshift information to the automatic transmission control unit to realize downshift and deceleration. And, the accurate gear shifting point (namely, the target gear) in the gear shifting process is determined through the gear ratio model, so that the target deceleration is realized. Thus, the invention avoids uncomfortable feeling caused by frequent active intervention braking of the running stability system of the vehicle. In addition, the invention realizes the support of the vehicle driver in a running mode of saving resources by recycling the kinetic energy in the deceleration process.

Drawings

Fig. 1 is a schematic block diagram of a driving assistance system according to one possible embodiment of the invention.

Fig. 2 shows a layout of the driving assistance system in fig. 1 in a vehicle.

Fig. 3 is a schematic block diagram of a deceleration control unit of the driving assistance system in fig. 1.

Fig. 4 is a flowchart of a deceleration control method for assisting in driving a vehicle according to one possible embodiment of the invention.

Detailed Description

The present invention relates generally to longitudinal control of a driving assistance system of a vehicle, which is capable of providing an improved deceleration control strategy for the vehicle. In the present invention, the vehicle refers to a vehicle with an automatic transmission, for example, an automatic transmission vehicle. The invention is applicable to conditions where the vehicle has a small deceleration requirement, for example where the vehicle is traveling on a flat ground with a small deceleration (e.g. due to a front vehicle decelerating or the like) or where the vehicle is traveling on a long and gentle downhill slope with a fixed vehicle speed.

Various embodiments of the present invention are described in detail below with reference to the attached drawing figures.

Fig. 1 schematically depicts a driving assistance system 100 according to one possible embodiment of the invention. For clarity, the layout of the driving assistance system 100 in the vehicle 1 is shown in fig. 2. Referring to fig. 1 and 2, the driving assistance system 100 mainly includes a forward sensor 10 and a controller 20. The controller 20 may be configured as a separate component from the forward sensor 10 or may be configured as an integrated component with the forward sensor 10. The controller 20 may be communicatively connected to other systems or components of the vehicle 1, such as the engine management system 200, the transmission system 300, and the travel stability system 400, via a vehicle communication bus 2 (e.g., a CAN bus).

The driving assistance system 100 is mounted on the vehicle 1. The driving assistance system 100 may be implemented by means of an adaptive cruise control system (e.g. ACC) of the vehicle 1. In embodiments where the driving assistance system 100 is implemented by means of an ACC system, the forward sensor 10 and the controller 20 may be implemented by means of sensors and electronic control units of the ACC system, e.g. an ACC-SCU. The driving assistance system 100 may also be implemented by means of a radar system of the vehicle 1. In embodiments where the driving assistance system 100 is implemented by means of a radar system, the forward sensor 10 may be implemented as a radar sensor and the controller 20 may be implemented as a controller that is provided separately or integrated with the radar sensor.

The forward sensor 10 may be implemented using a plurality of forward sensors, a sensor array, a plurality of sensing components, and a plurality of different types of sensors. The forward sensor 10 may be located anywhere on or in the vehicle 1, particularly adapted for mounting at a front portion of the vehicle 1. The forward sensor 10 may have a field of view that extends at least partially to include a roadway region in a forward direction of travel and to an adjacent roadway.

In some embodiments, the forward sensor 10 comprises a radar sensor that transmits signals from the vehicle 1 and receives reflected signals indicative of position, distance, and relative speed including a front potential collision object (e.g., a front vehicle), thereby measuring the relative speed and relative distance of the vehicle 1 to the front potential collision object. The forward sensor 10 may also include a camera that captures images and video of a potential collision object in front (e.g., a lead car). In embodiments where the forward sensor 10 includes a camera, the relative distance, relative speed, relative position, and other parameters between the vehicle 1 and the front potential collision object may be determined by various image or video processing techniques.

The controller 20 includes a plurality of electrical and electronic components that provide power, control logic, and protection to the components and modules therein. The controller 20 may be implemented as a single controller or in several separate controllers (e.g., programmable electronic control units or application specific integrated circuits ASICs), each configured to perform a particular function or sub-function. The controller 20 includes a control unit 30 configured to provide a deceleration control strategy for the vehicle 1 based on sensed data from the forward sensor 10 and other sensors.

According to the deceleration control strategy of the invention, first the driving assistance system 100 first determines whether the downshift deceleration condition is satisfied, and in the case where it is determined that the downshift deceleration condition is satisfied, calculates an accurate shift point (i.e., a target gear) for the vehicle 1, and the driving assistance system 100 sends the shift point information to the automatic transmission control unit 310 of the power train 300 to perform shift deceleration. In the case where it is determined that the downshift deceleration condition is not satisfied, the driving assistance system 100 activates the deceleration control unit 410 of the running stability system 400 to enable braking deceleration.

The deceleration control unit 30 includes a plurality of functional modules, which may be implemented in a single controller constituting the controller 20, or may be implemented in a plurality of controllers constituting the controller 20 according to functions. The deceleration control unit 30 and its respective functional modules may be implemented in software or hardware or in a combination of software and hardware.

It follows that among the elements for implementing the driving assistance system 100 of the present invention, the hardware part concerned can be implemented by means of the sensing means and the control means in the vehicle 1, and the control strategy part concerned can be implemented by means of software updating or redesigning or functional fusion, or by means of redesigning the hardware circuit in the control means. Therefore, the driving assistance system of the invention has the advantages of high development speed and low cost.

The functional blocks of the deceleration control unit 30 and the operation principle thereof are described below.

As shown in fig. 3, the deceleration control unit 30 mainly includes an acquisition module 32, a judgment module 34, a calculation module 36, a determination module 38, and a recovery module 39. Although the modules are shown in fig. 3 to be connected in sequence, the connection manner of the modules is not limited thereto, and in order to cooperate with the technical scheme of the present invention, any two of the modules may perform data interaction.

The acquisition module 32 acquires the deceleration request and acquires parameter values for subsequent operations from the forward sensor 10 and other sensors of the vehicle 1. The acquisition module 32 acquires a gradient value, i.e., an actual gradient value, of the road surface on which the vehicle 1 is traveling from a gradient sensor. The acquisition module 32 acquires the relative speed and the relative distance between the vehicle 1 and a front potential collision object (e.g., a preceding vehicle) from the forward sensor 10. The acquisition module 32 acquires an engine speed (i.e., a current engine speed) from an engine speed sensor 210 in the engine management system 200, and acquires a wheel speed (i.e., a current wheel speed of the vehicle 1) from a wheel speed sensor (not shown) coupled to a wheel, thereby obtaining a current gear ratio (i.e., a ratio of the engine speed to the wheel speed) of the vehicle 1. Of course, the step of calculating the ratio of engine speed to wheel speed by the module 34 may also be performed to obtain the current gear ratio. The acquisition module 32 the torque sensor 220 in the engine management system 200 acquires the engine torque (i.e., the current engine torque).

It should be appreciated that in the present invention, the deceleration request is generated by the control device (e.g., the controller 20) of the driving assistance system 100 when there is a deceleration demand for the operating condition of the vehicle 1 and the deceleration demand is sensed by the sensing device (e.g., the forward sensor 10) of the driving assistance system 100.

It should be appreciated that the parameters described above may also be obtained in other ways. For example, the acquisition module 32 acquires accelerations along a plurality of dimensions from the acceleration sensor, and then obtains gradient values of the road surface on which the vehicle 1 is traveling, from these accelerations.

Next, the deceleration control unit 30 executes control logic for determining whether the vehicle 1 satisfies the condition for downshift deceleration. In the present invention, two conditions (i.e., deceleration and gradient values) are employed to determine whether the vehicle 1 is suitable for deceleration with a downshift. It should be appreciated that the determination logic for these two conditions is not limited to a sequential order and may be performed in any order. For convenience of description, description will be given taking as an example the order in which the determination logic regarding the deceleration is executed first and then the determination logic regarding the gradient value is executed.

The calculation module 36 calculates a target deceleration of the vehicle 1 based on the travel data of the vehicle 1 acquired by the acquisition module 32. Next, the determination module 34 determines whether to enable the control logic for downshifting deceleration or the control logic for braking deceleration based on the target deceleration and the deceleration threshold. When the target deceleration is greater than the deceleration threshold, the determination module 34 determines that it is not appropriate (prohibited) to decelerate in the manner of a downshift, and sends a deceleration request (or the deceleration request together with the target deceleration) to the deceleration control module 410 of the running stability system 400 (e.g., the CDD module of the ESP system) to perform a braking manipulation by the running stability system 400, thereby achieving the target deceleration in the manner of a braking deceleration. When the target deceleration is equal to or less than the deceleration threshold, the determination module 34 determines that deceleration is permitted (appropriate) in the manner of a downshift, thereby continuing to execute the control logic of the downshift deceleration.

The deceleration threshold may be a value set empirically or experimentally. For example, the automatic transmission of the vehicle 1 is reduced by two or more gear steps to amplify the engine reverse torque, whereby the achievable deceleration is used as the deceleration threshold. Thus, when the target deceleration is greater than the deceleration threshold value, it means that the target deceleration cannot be achieved even if two or more gear steps are reduced, and reducing two or more gear steps from the current gear step significantly reduces the comfort and safety of the vehicle 1. Therefore, such a case where the target deceleration is too large is considered unsuitable for deceleration by the downshift method.

Regarding the calculation of the target deceleration, there may occur two cases, that is, a case where there is a potential collision object (for example, a preceding vehicle) in front of the vehicle 1 (i.e., the host vehicle) and a case where there is no potential collision object in front of the vehicle 1.

In the case where the front sensor 10 detects that there is a potential collision object in front of the vehicle 1, the calculation module 36 calculates the target deceleration of the vehicle 1 based on the relative speed and the relative distance of the vehicle 1 and the front potential collision object. For example, the calculation module 36 calculates the target deceleration of the host vehicle according to the following formula:

a_Tar＝(V1-V2)^2/2S，

where a _Tar is the target deceleration of the vehicle 1, V1 is the speed of the vehicle 1, V2 is the speed of the front potential collision object (e.g., the speed of the front vehicle), V1-V2 is the relative speed of both (which can be measured by the forward sensor 10), and S is the relative distance of the vehicle 1 from the front potential collision object (which can be measured by the forward sensor 10).

In the case where the front sensor 10 does not detect that there is a potential collision object in front of the vehicle 1, the calculation module 36 calculates the target deceleration of the vehicle 1 based on the vehicle speed of the vehicle 1 and the vehicle speed set by the driver. For example, the calculation module 36 calculates the target deceleration of the vehicle 1 according to the following formula:

a_Tar＝(Vset-V1)/T，

Where a _Tar is the target deceleration of the vehicle 1, vset is the vehicle speed of the vehicle 1 set by the driver (for example, the set vehicle speed input by the driver through the man-machine interface in the vehicle 1), V1 is the vehicle speed of the vehicle 1, and T is a time constant, which may be a value set in advance in the driving assistance system 100.

In the grade value-based determination logic, the determination module 34 determines whether to enable the downshift deceleration control logic or the brake deceleration control logic based on the actual grade value and the grade threshold. When the actual gradient value is greater than the gradient threshold value, it is determined that it is not appropriate to decelerate in the downshift manner, and the determination module 34 sends a deceleration request (or the deceleration request together with the target deceleration) to the deceleration control module 410 of the running stability system 400 (e.g., the CDD module of the ESP system) to perform a braking manipulation by the running stability system, thereby achieving the target deceleration. When the gradient value is equal to or less than the gradient threshold value, the determination module 34 determines that the downshift is permitted (appropriate) to be performed in order to continue the control logic of the downshift.

The gradient threshold is a value set empirically and experimentally. The gradient threshold value is a small gradient value, for example, 10%, because when the gradient value is greater than a certain value, the vehicle 1 needs to be rapidly decelerated to activate the braking function. That is, the invention is applicable to conditions where flat ground is required to be decelerated or a relatively gentle long downhill slope is required to be kept at a constant speed.

After the determination module 34 completes the determination regarding both the gradient value and the deceleration, the calculation module 36 calculates the target gear ratio i _Tar of the vehicle 1 in the case where it is determined that the downshift is permitted in both aspects.

The calculation module 36 may calculate the target gear ratio i _Tar as follows. First, a deceleration difference Δa is calculated based on the actual deceleration and the target deceleration of the vehicle 1. The braking force difference af at the wheel end, that is, the difference between the braking force required at the wheels of the vehicle (the sum of the braking forces required for all the wheels of the vehicle 1) and the current actual braking force (the sum of the current braking forces for all the wheels of the vehicle 1) in order to achieve the target deceleration is calculated based on the deceleration difference Δa and the mass m of the vehicle 1. Next, a wheel end torque difference Δt, that is, a difference between the torque required at the wheels and the actual torque in order to achieve the target deceleration, is calculated based on the braking force difference Δf and the wheel radius r. The current gear ratio of the vehicle 1 may be calculated based on the ratio of the current engine speed to the current wheel speed. The current wheel end torque T is calculated based on the current gear ratio and the current engine torque. The current wheel end torque T and the calculated wheel end torque difference Δt are added to obtain a target wheel end torque T _Tar, i.e., a torque required at the wheels in order to achieve a target deceleration. Then, a target gear ratio i _Tar is calculated based on the target wheel end torque T _Tar and the current engine torque.

After the calculation module calculates the target gear ratio i _Tar, the determination unit determines the target gear G _Tar for the vehicle 1, i.e., a gear that brings the vehicle 1 to the target gear ratio i _Tar. The determination module 38 determines the target gear G _Tar by means of the gear ratio model and transmits the target gear G _Tar to the transmission system 300 of the vehicle 1, for example, to an automatic Transmission Control Unit (TCU) 310 of the transmission system 300, so that the automatic transmission control unit 310 controls the automatic transmission of the vehicle 1 to shift (decrease) from the current gear to the target gear G _Tar.

The gear ratio model is a function that represents the correspondence between the gear ratio and the gear position of the automatic transmission of the vehicle 1 during shifting. The function may be derived by physical experimentation, theoretical calculation, or simulation fit, as well as combinations thereof. For example, by a real vehicle test, multiple sets of data for gear ratios and gear steps during a shift are measured, and then a mathematical calculation or curve fitting is used to obtain the correspondence between the two (e.g., a gear ratio-gear step curve). A gear ratio difference is calculated based on the target gear ratio and the current gear ratio, and a determination is made on a gear ratio-gear curve as to which gear is to be changed (reduced) from the current gear to achieve the target gear ratio.

Accurate determination of the target gear is an important factor in achieving the target deceleration. When the vehicle is running in a certain gear, the gear has a predetermined correspondence (matching relationship) with the gear ratio. However, during a gear change, the gear ratio may have a continuously changing (or irregular step change) process in which the gear ratio does not completely follow a predetermined relationship. Therefore, it is of great significance to measure the transmission ratio corresponding to each gear in the gear shifting process through a real vehicle, and fit a transmission ratio-gear curve in the gear shifting process through a mathematical model, so that a transmission ratio model is obtained.

In addition, the vehicle 1 may have a regenerative braking system (e.g., RBS). The recuperation module 39 of the deceleration control unit 30 can generate a command for indicating to recuperate the energy and send the command to the regenerative braking system. The instruction is for instructing the regenerative braking system to recover and reuse the kinetic energy during gear shifting deceleration, for example, to convert the kinetic energy into electric energy to be supplied to a battery or electric device of the vehicle 1.

Fig. 4 shows a deceleration control method 400 for assisting in driving the vehicle 1 according to one possible embodiment of the invention. The method may be implemented by the deceleration control unit 30 or by the driving assistance system 100. Accordingly, the above description regarding the deceleration control unit 30 and the driving assistance system 100 also applies thereto.

Referring to fig. 4, in step S410, the acquisition module 32 acquires a deceleration request and a parameter value for a subsequent operation.

Next, in step S420, the determination module 34 determines whether the target deceleration is equal to or less than a deceleration threshold.

In the case where the determination module 34 determines "no" in step S420, the method 400 proceeds to step S430. In step S430, the determination module 34 activates a deceleration control module of the running stability system to perform braking manipulation.

In the case where the determination module 34 determines "yes" in step S420, the method 400 proceeds to step S440. In step S440, the determination module 34 determines whether the current grade value is less than or equal to the grade threshold.

In the case where the determination module 34 determines "no" in step S440, the method 400 proceeds to step S430. In step S430, the determination module 34 activates a deceleration control module of the running stability system to perform braking manipulation.

In the event that determination module 34 determines yes in step S440, method 400 proceeds to step S450. In step S450, the calculation module 36 calculates a difference between the current deceleration and the target deceleration.

Next, steps S460 to S495 are sequentially performed.

In step S460, the calculation module 36 calculates a wheel end braking force difference. In step S470, the calculation module 36 calculates a wheel end torque difference. In step S480, the calculation module 36 calculates a wheel end target torque. In step S490, the calculation module 36 calculates a target gear ratio. In step S495, the determination module 38 determines the target gear.

In the method 400, step S420 and step S440 may be performed in any order or simultaneously.

According to the technical scheme of the invention, whether the control logic for downshifting and decelerating is suitable for being adopted is judged based on the working condition of the vehicle, so that the control logic for downshifting and decelerating can be started under the condition that the working condition of the vehicle is suitable. In the event that the operating conditions of the vehicle are not suitable for downshift deceleration, the control logic for braking deceleration is enabled. Thus, the control logic of the two aspects can be adapted in cooperation. According to the control logic for downshift and deceleration, the accurate target gear suitable for gear shifting can be determined, and the target gear information is sent to the automatic gear shifter control unit of the vehicle through the driving auxiliary system, so that uncomfortable feeling caused by frequent active intervention braking of the driving stability system of the vehicle is avoided. In addition, by recycling the kinetic energy in the deceleration process, the vehicle driver is supported in a resource-saving driving mode.

While the foregoing describes some embodiments, these embodiments are given by way of example only and are not intended to limit the scope of the invention. The appended claims and their equivalents are intended to cover all modifications, substitutions and changes made within the scope and spirit of the invention.

Claims (11)

1. A deceleration control unit for a driving assistance system of a vehicle, wherein the vehicle is a vehicle with an automatic transmission, includes an acquisition module, a calculation module, a judgment module, and a determination module,

The acquisition module acquires a deceleration request and running data of the vehicle, wherein the running data at least comprises current deceleration and current transmission ratio;

The calculation module calculates a target deceleration of the vehicle in response to the deceleration request, the judgment module judges whether the target deceleration is equal to or smaller than a deceleration threshold, and if the judgment result is affirmative, the calculation module calculates a target gear ratio for the vehicle to reach the target deceleration based on a difference between the target deceleration and a current deceleration; and

The determination module determines a target gear that causes the vehicle to reach the target gear based on a difference between the target gear and a current gear and a gear model that is a function that represents a correspondence between gears of the automatic transmission and gears of the automatic transmission during a shift, and sends the target gear to an automatic transmission control unit of the vehicle,

The transmission ratio model is obtained based on multiple groups of data of transmission ratios and gears in a gear shifting process which are measured through experiments, and the multiple groups of data are processed through at least one mode of theoretical calculation and curve fitting.

2. The deceleration control unit according to claim 1, wherein in the case where the determination result is negative, operations of the calculation module and the determination module are prohibited, and the determination module sends a deceleration request to a running stability system of the vehicle to achieve a target deceleration through brake manipulation.

3. The deceleration control unit according to claim 1, wherein the deceleration threshold corresponds to a deceleration value by which the automatic transmission decreases two or more gear steps so that the vehicle achieves.

4. The deceleration control unit according to claim 1, wherein the acquisition module acquires a gradient value of a road on which the vehicle is traveling;

the judging module judges whether the acquired gradient value is smaller than or equal to a gradient threshold value;

allowing operation of the calculation module and the determination module if the judgment result is affirmative;

In the case where the determination result is negative, operations of the calculation module and the determination module are prohibited, and the determination module sends a deceleration request to a running stability system of the vehicle to achieve a target deceleration by brake manipulation.

5. The deceleration control unit according to claim 1, wherein in the case where there is a potential collision object in front of the vehicle, the calculation module calculates the target deceleration in response to a deceleration request and based on a relative speed and a relative distance of the vehicle and the potential collision object; and

In the case where there is no potential collision object in front of the vehicle, the calculation unit calculates a target deceleration in response to a deceleration request and based on a set vehicle speed input by the vehicle driver.

6. The deceleration control unit according to claim 1, wherein in the case where there is a potential collision object in front of the vehicle, the calculation module calculates the target deceleration in response to a deceleration request based on the following formula: a _Tar = (V1-V2)/(2/2S), where a _Tar is the target deceleration, (V1-V2) and S are the relative speed and relative distance between the vehicle and the front potential collision object, respectively; and

In the case where there is no potential collision object in front of the vehicle, the calculation unit calculates a target deceleration in response to a deceleration request based on the following formula: a _Tar = (Vset-V1)/T, where a _Tar is a target deceleration, vset is a vehicle speed set by a driver of the vehicle, V1 is a vehicle speed of the vehicle, and T is a value set in advance in the driving assistance system.

7. The deceleration control unit according to claim 1, wherein the calculation module calculating the target gear ratio based on a difference between a target deceleration and a current deceleration includes:

calculating a braking force required to be increased on wheels of the vehicle to achieve the target deceleration based on the difference,

Calculating a torque required to be increased at the wheel based on the required increased braking force and the wheel radius;

calculating a current torque at the wheels based on the current gear ratio and the current engine torque;

calculating a target torque at the wheel based on the current torque at the wheel and the torque that needs to be increased; and

The target gear ratio is calculated based on a target torque at the wheels and a current transmitter torque.

8. The deceleration control unit of claim 1, wherein the deceleration control unit further comprises a recovery module configured to generate a recovery instruction for instructing recovery of kinetic energy of the vehicle during deceleration and converting the kinetic energy into electrical energy for provision to a battery or powered device of the vehicle.

9. A driving assistance system for a vehicle, the vehicle being a vehicle with an automatic transmission, the driving assistance system comprising:

a forward sensor for sensing travel data of the vehicle;

A controller electrically connected to the forward sensor and in communication with an engine management system and a driveline of the vehicle via a vehicle communication bus, the controller comprising the deceleration control unit of any one of claims 1-8, the deceleration control unit performing deceleration control in response to a deceleration request and based on data from the forward sensor and data from the engine management system and driveline to achieve a target deceleration.

10. The driving assistance system according to claim 9, wherein the forward sensor includes at least a radar sensor; and

The driving assistance system is an adaptive cruise control system or a radar system or a combination of both of the vehicle.

11. A deceleration control method for a vehicle for assisting in driving the vehicle, the vehicle being a vehicle with an automatic transmission, the method being implemented by means of a deceleration control unit according to any one of claims 1-8 and/or a driving assistance system according to any one of claims 9-10, the method comprising:

acquiring a deceleration request and running data of the vehicle, wherein the running data at least comprises current deceleration and current transmission ratio;

calculating a target deceleration of the vehicle in response to the deceleration request;

judging whether the target deceleration is smaller than or equal to a deceleration threshold value;

in the case where the determination result is affirmative, calculating a target gear ratio that causes the vehicle to reach the target deceleration based on a difference between the target deceleration and the current deceleration;

Determining a target gear for enabling the vehicle to reach the target gear based on a difference value between the target gear and a current gear and a gear ratio model, wherein the gear ratio model is a function which is obtained through at least one of physical experiments, theoretical calculation and simulation fitting and represents a corresponding relation between the gear ratio and the gear of the automatic transmission in a gear shifting process; and

The target gear is transmitted to an automatic transmission control unit of the vehicle,

The transmission ratio model is obtained based on multiple groups of data of transmission ratios and gears in a gear shifting process which are measured through experiments, and the multiple groups of data are processed through at least one mode of theoretical calculation and curve fitting.