CN112824187A - Driving assistance system, and deceleration control unit and method therefor - Google Patents

Driving assistance system, and deceleration control unit and method therefor Download PDF

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Publication number
CN112824187A
CN112824187A CN201911145379.4A CN201911145379A CN112824187A CN 112824187 A CN112824187 A CN 112824187A CN 201911145379 A CN201911145379 A CN 201911145379A CN 112824187 A CN112824187 A CN 112824187A
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vehicle
deceleration
target
gear ratio
control unit
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CN112824187B (en
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朱传奇
杨惠宇
王立华
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Bosch Automotive Products Suzhou Co Ltd
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Bosch Automotive Products Suzhou Co Ltd
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60W—CONJOINT CONTROL OF VEHICLE SUB-UNITS OF DIFFERENT TYPE OR DIFFERENT FUNCTION; CONTROL SYSTEMS SPECIALLY ADAPTED FOR HYBRID VEHICLES; ROAD VEHICLE DRIVE CONTROL SYSTEMS FOR PURPOSES NOT RELATED TO THE CONTROL OF A PARTICULAR SUB-UNIT
    • B60W30/00—Purposes of road vehicle drive control systems not related to the control of a particular sub-unit, e.g. of systems using conjoint control of vehicle sub-units
    • B60W30/18—Propelling the vehicle
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60W—CONJOINT CONTROL OF VEHICLE SUB-UNITS OF DIFFERENT TYPE OR DIFFERENT FUNCTION; CONTROL SYSTEMS SPECIALLY ADAPTED FOR HYBRID VEHICLES; ROAD VEHICLE DRIVE CONTROL SYSTEMS FOR PURPOSES NOT RELATED TO THE CONTROL OF A PARTICULAR SUB-UNIT
    • B60W10/00—Conjoint control of vehicle sub-units of different type or different function
    • B60W10/04—Conjoint control of vehicle sub-units of different type or different function including control of propulsion units
    • B60W10/06—Conjoint control of vehicle sub-units of different type or different function including control of propulsion units including control of combustion engines
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60W—CONJOINT CONTROL OF VEHICLE SUB-UNITS OF DIFFERENT TYPE OR DIFFERENT FUNCTION; CONTROL SYSTEMS SPECIALLY ADAPTED FOR HYBRID VEHICLES; ROAD VEHICLE DRIVE CONTROL SYSTEMS FOR PURPOSES NOT RELATED TO THE CONTROL OF A PARTICULAR SUB-UNIT
    • B60W10/00—Conjoint control of vehicle sub-units of different type or different function
    • B60W10/10—Conjoint control of vehicle sub-units of different type or different function including control of change-speed gearings
    • B60W10/11—Stepped gearings
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60W—CONJOINT CONTROL OF VEHICLE SUB-UNITS OF DIFFERENT TYPE OR DIFFERENT FUNCTION; CONTROL SYSTEMS SPECIALLY ADAPTED FOR HYBRID VEHICLES; ROAD VEHICLE DRIVE CONTROL SYSTEMS FOR PURPOSES NOT RELATED TO THE CONTROL OF A PARTICULAR SUB-UNIT
    • B60W2520/00—Input parameters relating to overall vehicle dynamics
    • B60W2520/10—Longitudinal speed
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60W—CONJOINT CONTROL OF VEHICLE SUB-UNITS OF DIFFERENT TYPE OR DIFFERENT FUNCTION; CONTROL SYSTEMS SPECIALLY ADAPTED FOR HYBRID VEHICLES; ROAD VEHICLE DRIVE CONTROL SYSTEMS FOR PURPOSES NOT RELATED TO THE CONTROL OF A PARTICULAR SUB-UNIT
    • B60W2520/00—Input parameters relating to overall vehicle dynamics
    • B60W2520/10—Longitudinal speed
    • B60W2520/105—Longitudinal acceleration
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60W—CONJOINT CONTROL OF VEHICLE SUB-UNITS OF DIFFERENT TYPE OR DIFFERENT FUNCTION; CONTROL SYSTEMS SPECIALLY ADAPTED FOR HYBRID VEHICLES; ROAD VEHICLE DRIVE CONTROL SYSTEMS FOR PURPOSES NOT RELATED TO THE CONTROL OF A PARTICULAR SUB-UNIT
    • B60W2710/00—Output or target parameters relating to a particular sub-units
    • B60W2710/06—Combustion engines, Gas turbines
    • B60W2710/0666—Engine torque
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60W—CONJOINT CONTROL OF VEHICLE SUB-UNITS OF DIFFERENT TYPE OR DIFFERENT FUNCTION; CONTROL SYSTEMS SPECIALLY ADAPTED FOR HYBRID VEHICLES; ROAD VEHICLE DRIVE CONTROL SYSTEMS FOR PURPOSES NOT RELATED TO THE CONTROL OF A PARTICULAR SUB-UNIT
    • B60W2710/00—Output or target parameters relating to a particular sub-units
    • B60W2710/10—Change speed gearings
    • B60W2710/1005—Transmission ratio engaged
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60W—CONJOINT CONTROL OF VEHICLE SUB-UNITS OF DIFFERENT TYPE OR DIFFERENT FUNCTION; CONTROL SYSTEMS SPECIALLY ADAPTED FOR HYBRID VEHICLES; ROAD VEHICLE DRIVE CONTROL SYSTEMS FOR PURPOSES NOT RELATED TO THE CONTROL OF A PARTICULAR SUB-UNIT
    • B60W2720/00—Output or target parameters relating to overall vehicle dynamics
    • B60W2720/10—Longitudinal speed
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60W—CONJOINT CONTROL OF VEHICLE SUB-UNITS OF DIFFERENT TYPE OR DIFFERENT FUNCTION; CONTROL SYSTEMS SPECIALLY ADAPTED FOR HYBRID VEHICLES; ROAD VEHICLE DRIVE CONTROL SYSTEMS FOR PURPOSES NOT RELATED TO THE CONTROL OF A PARTICULAR SUB-UNIT
    • B60W2720/00—Output or target parameters relating to overall vehicle dynamics
    • B60W2720/10—Longitudinal speed
    • B60W2720/106—Longitudinal acceleration

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Transportation (AREA)
  • Mechanical Engineering (AREA)
  • Automation & Control Theory (AREA)
  • Control Of Transmission Device (AREA)

Abstract

The invention provides a driving assistance system, and a deceleration control unit and 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 that causes the vehicle to reach 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 ratio based on a difference between the 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 representing the correspondence between gear ratio and gear of the automatic transmission during a gear shift.

Description

Driving assistance system, and deceleration control unit and method therefor
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 for a vehicle. The invention also relates to a driving assistance system having the deceleration control unit and a related deceleration control method.
Background
It is known to equip vehicles with driving assistance systems. The driving assist system of the vehicle includes various systems that perform different functions, for example, an adaptive cruise control system and a running stability system. The adaptive cruise control system can reduce the burden on the driver during the traveling of the vehicle, control the vehicle speed earlier before feeling tired, and easily and safely travel following a slower-traveling vehicle. The driving stability system can improve the controllability and the driving stability of the vehicle and expand the driving 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 driving stability system, whereby the driving stability system performs a braking maneuver to achieve deceleration of the vehicle. When the vehicle needs to decelerate several times over a long stretch of road or needs to decelerate slowly over a long period of time, it may happen that the stability system frequently performs active braking interventions, which may cause an uncomfortable driving experience.
Disclosure of Invention
The present invention aims to provide an improved deceleration control scheme for a driving-assist vehicle that 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 includes an acquisition module that acquires a deceleration request and travel data of the vehicle 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 determination module determines whether the target deceleration is equal to or less than a deceleration threshold, and in the case where the determination result is affirmative, the calculation module calculates a target gear ratio that causes 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 for bringing the vehicle to the target gear ratio based on a difference between the target gear ratio and a current gear ratio and a gear ratio model, which is a function representing a correspondence between the gear ratio and a gear of the automatic transmission during the gear shift, and transmits the target gear to an automatic transmission control unit of the vehicle.
According to one possible embodiment, the gear ratio model is based on experimentally measured sets of data of gear ratios and gears during the gear shift and is obtained by processing the sets of data by at least one of theoretical calculations and curve fitting.
According to one possible embodiment, in the case where the determination result is negative, the 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 a braking manipulation.
According to one possible embodiment, the deceleration threshold corresponds to a deceleration value that the automatic transmission reduces two or more gears so that the vehicle achieves.
According to a possible embodiment, the acquisition module acquires a value of the slope of the road on which the vehicle is running; the judging module judges whether the acquired gradient value is less than or equal to a gradient threshold value; in the case that the judgment result is positive, allowing the operation of the calculation module and the determination module; in the case where the determination result is negative, the 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 a braking manipulation.
According to one possible embodiment, 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 to the potential collision object in a case where there is a potential collision object in front of the vehicle; and 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 in a case where there is no potential collision object in front of the vehicle.
According to one possible embodiment, the calculation module calculates the target deceleration in response to the deceleration request and based on the following formula in the case where there is a potential collision object in front of the vehicle: (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 preceding potential collision object, respectively; and in a 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 the following formula: where aTar is a target deceleration, Vset is a vehicle speed set by a driver of the vehicle, V1 is the vehicle speed of the vehicle, and T is a value set in advance in the driving assistance system.
According to one possible embodiment, the calculation module calculating the target gear ratio based on the difference between the target deceleration and the current deceleration comprises: calculating a required increased braking force on a wheel of the vehicle to achieve the target deceleration based on the difference, calculating a required increased torque at the wheel based on the required increased braking force and a wheel radius; calculating a current torque at the wheel 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 engine torque.
According to one possible embodiment, the deceleration control unit further comprises a recovery module configured to generate a recovery command for instructing recovery of kinetic energy of the vehicle during deceleration and conversion of the kinetic energy into electrical energy for supply to a battery or a 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 including: a forward sensor for sensing travel data of the vehicle; a controller electrically connected to the forward sensor and communicatively connected to an engine management system and a driveline of the vehicle via a vehicle communication bus, the controller comprising a deceleration control unit according to any one of claims 1 to 9, 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 the driveline to achieve a target deceleration.
According to a possible embodiment, said forward sensors comprise at least radar sensors; 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 invention, there is provided a deceleration control method for a vehicle for assisting in driving the 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 a current deceleration and a current transmission ratio; calculating a target deceleration of the vehicle in response to the deceleration request; determining whether the target deceleration is less than or equal to a deceleration threshold; in the case where the determination result is affirmative, calculating a target gear ratio that causes the vehicle to reach a target deceleration, based on a difference between the target deceleration and a current deceleration; determining a target gear for enabling the vehicle to reach the target gear ratio based on a difference between the target gear ratio and a current gear ratio and a gear ratio model, wherein the gear ratio model is a function representing a corresponding relation between the gear ratio and a gear of the automatic transmission in a gear shifting process, and the function is obtained through at least one of physical experiments, theoretical calculation and simulation fitting; 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 deceleration. And, a precise shift point (i.e., a target gear) during the shift is determined through the gear ratio model so as to achieve the target deceleration. Thus, the invention avoids uncomfortable feeling caused by frequent active intervention of braking of a driving stability system of the vehicle. In addition, the invention realizes the support of the vehicle driver in a resource-saving driving mode 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 assist system in fig. 1 in a vehicle.
Fig. 3 is a schematic block diagram of a deceleration control unit of the driving assist system in fig. 1.
Fig. 4 is a flowchart of a deceleration control method for a driving-assist vehicle according to one possible embodiment of the invention.
Detailed Description
The present invention generally relates 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 means a vehicle with an automatic transmission, for example, an automatic transmission vehicle. The invention is applicable to conditions where the vehicle has a smaller deceleration requirement, for example, where the vehicle is traveling on a level ground requiring a smaller deceleration (e.g., due to a preceding vehicle deceleration, etc.), or where the vehicle is traveling on a longer and gentle downhill requiring a fixed vehicle speed to be maintained.
Hereinafter, various embodiments of the present invention will be described in detail with reference to the accompanying drawings.
Fig. 1 schematically shows 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 to be integrated with the forward sensor 10. Controller 20 may be communicatively connected to other systems or components of vehicle 1, such as engine management system 200, drive train system 300, and ride stability system 400, via a vehicle communication bus 2 (e.g., a CAN bus).
The driving assist system 100 is mounted on the vehicle 1. The driving assist system 100 may be realized by an adaptive cruise control system (for example, ACC) of the vehicle 1. In the embodiment in which 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 an electronic control unit of the ACC system, for example, ACC-SCU. The driving assistance system 100 may also be implemented by means of a radar system of the vehicle 1. In an embodiment 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 provided separately from or integrated with the radar sensor.
The forward sensor 10 may be implemented using multiple forward sensors, a sensor array, multiple sensing components, and multiple different types of sensors. The forward sensor 10 may be located anywhere on or within the vehicle 1 and is particularly adapted to be mounted at a forward portion of the vehicle 1. The forward sensor 10 may have a field of view that extends at least partially to a traffic lane area including in the forward driving direction and to an adjacent traffic lane.
In some embodiments, forward sensor 10 comprises a radar sensor that transmits signals from vehicle 1 and receives reflected signals indicative of a location, distance, and relative speed including a potential collision object in front (e.g., a leading vehicle), thereby measuring the relative speed and relative distance of vehicle 1 from the potential collision object in front. The forward facing sensor 10 may also include a camera that captures images and video of a potential collision object (e.g., a leading vehicle) in front. In embodiments where the forward sensor 10 comprises a camera, the relative distance, relative speed, relative position, and other parameters between the vehicle 1 and the potential collision object in front may be determined by means of various image or video processing techniques.
The controller 20 includes a number 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 specific 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 present invention, first, the drive assist system 100 first determines whether or not the downshift deceleration condition is satisfied, calculates an accurate shift point (i.e., a target gear) for the vehicle 1 in the case where it is determined that the downshift deceleration condition is satisfied, and the drive assist system 100 transmits the shift point information to the automatic transmission control unit 310 of the power transmission system 300 to perform the shift deceleration. In the case where it is determined that the downshift deceleration condition is not satisfied, the drive assist 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 blocks, which may be implemented in a single controller constituting the controller 20 or in a plurality of controllers constituting the controller 20 according to functions. The deceleration control unit 30 and its functional modules may be implemented in software or hardware or in a combination of software and hardware.
It can be seen that, in the elements for implementing the driving assistance system 100 of the present invention, the hardware components involved can be implemented by the sensing device and the control device in the vehicle 1, and the control strategy components involved can be implemented by software update or redesign or function fusion, or by redesigning the hardware circuit in the control device. Therefore, the driving assistance system of the invention has the advantages of fast development speed and low cost.
The functional blocks of the deceleration control unit 30 and the operation principle thereof will be 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 fig. 3 illustrates that these modules are connected in sequence, the connection manner of these modules is not limited thereto, and any two of these modules may perform data interaction in order to cooperate with the technical solution of the present invention.
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 of a road surface on which the vehicle 1 is running, i.e., an actual gradient value, from a gradient sensor. The acquisition module 32 acquires the relative speed and the relative distance between the vehicle 1 and a preceding potential collision object (for example, 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 of the vehicle 1 (i.e., a ratio of the engine speed to the wheel speed). Of course, it is also possible that the calculation module 34 performs the step of comparing the engine speed to the wheel speed to obtain the current gear ratio. The torque sensor 220 in the engine management system 200 of the acquisition module 32 acquires an engine torque (i.e., a current engine torque).
It should be understood that, in the present invention, the deceleration request is generated by a control device (e.g., the controller 20) of the driving assistance system 100 when the vehicle 1 is in a condition where there is a deceleration demand and is sensed by a sensing device (e.g., the forward sensor 10) of the driving assistance system 100.
It should be understood that the above parameters may be obtained in other ways. For example, the acquisition module 32 acquires accelerations along a plurality of dimensions from an acceleration sensor, and then derives a gradient value of a road surface on which the vehicle 1 is running 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 value) are employed to determine whether the vehicle 1 is suitable for employing downshift deceleration. It should be understood that the decision logic for these two conditions does not define a sequential order, and may be performed in any order. For convenience of description, description will be made taking as an example the order in which the determination logic regarding deceleration is executed first and then the determination logic regarding gradient value is executed.
The calculation module 36 calculates the target deceleration of the vehicle 1 based on the running data of the vehicle 1 acquired by the acquisition module 32. Next, the determination module 34 determines whether to enable the control logic for downshift deceleration or the control logic for brake 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 a downshift manner, and sends a deceleration request (or a deceleration request together with the target deceleration) to a deceleration control module 410 (e.g., a CDD module of the ESP system) of the running stability system 400 to perform a braking manipulation by the running stability system 400 to achieve the target deceleration in a braking deceleration manner. When the target deceleration is equal to or less than the deceleration threshold, the determination module 34 determines that deceleration by downshift is permitted (appropriate), and thus continues to execute the control logic for downshift deceleration.
The deceleration threshold may be a value set based on experience or experiment. For example, the automatic transmission of the vehicle 1 is lowered by two or more shifts to amplify the engine anti-drag torque, and the deceleration thus enabled serves as the deceleration threshold. In this way, when the target deceleration is larger than the deceleration threshold value, it means that the target deceleration cannot be achieved even if the two or more gear steps are reduced, and the reduction of the 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 to be unsuitable for deceleration by the downshift.
With regard to 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 own 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 a potential collision object in front of the vehicle 1, the calculation module 36 calculates a target deceleration of the vehicle 1 based on the relative speed and the relative distance of the vehicle 1 and the potential collision object in front. For example, the calculation module 36 calculates the target deceleration of the host vehicle according to the following equation:
aTar＝(V1-V2)^2/2S，
wherein, aTarFor the target deceleration of the vehicle 1, V1 is the vehicle speed of the vehicle 1, V2 is the speed of the preceding potential collision object (e.g., the vehicle speed of the preceding vehicle), and (V1-V2) is the relative speed of the two (which may be the relative speedMeasured by the forward sensor 10), S is the relative distance of the vehicle 1 from a potential collision object in front (which may be measured by the forward sensor 10).
In the case where the front sensor 10 does not detect a potential collision object in front of the vehicle 1, the calculation module 36 calculates a 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 equation:
aTar＝(Vset-V1)/T，
wherein, aTarVset is a vehicle speed of vehicle 1 set by the driver (e.g., a set vehicle speed input by the driver via an hmi in vehicle 1), V1 is the vehicle speed of vehicle 1, and T is a time constant, which may be a value preset in driving assistance system 100, for a target deceleration of vehicle 1.
In the slope value based determination logic, the determination module 34 determines whether to enable the control logic for the downshift deceleration or the control logic for the brake deceleration based on the actual slope value and a slope threshold value. 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 transmits a deceleration request (or a deceleration request together with a target deceleration) to a deceleration control module 410 (e.g., a CDD module of the ESP system) of the running stability system 400 to perform a braking manipulation by the running stability system to achieve 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 mode is permitted (appropriate) to be decelerated, thereby continuing the control logic for executing the downshift deceleration.
The gradient threshold value is a value set empirically and experimentally. The gradient threshold value is a small gradient value, for example 10%, since the vehicle 1 needs to be decelerated quickly to activate the braking function when the gradient value is greater than a certain value. That is to say, the invention is suitable for the working condition that the speed is required to be reduced on flat ground or the constant speed is required to be kept on a milder long downhill.
In the case where it is determined that the employment of downshift deceleration is permitted in both aspects after the determination module 34 has completed the determination in both aspects regarding the gradient value and the deceleration, the calculation module36 calculate a target gear ratio i of the vehicle 1Tar。
The calculation module 36 may calculate the target gear ratio i using the following methodTar. First, the deceleration difference Δ a is calculated based on the actual deceleration of the vehicle 1 and the target deceleration. A wheel-end braking force difference Δ F, that is, a difference between the braking force required at the wheels of the vehicle (sum of all the wheel required braking forces of the vehicle 1) and the current actual braking force (sum of all the wheel current braking forces of the vehicle 1) to achieve the target deceleration is calculated based on the deceleration difference Δ a and the mass m of the vehicle 1. Next, a wheel-end torque difference Δ T, that is, a difference between a torque required at the wheels to achieve the target deceleration and an actual torque, is calculated based on the braking force difference Δ F 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. Adding the current wheel end torque T and the calculated wheel end torque difference delta T to obtain a target wheel end torque TTarI.e. the torque required at the wheels in order to achieve the target deceleration. Then, based on the target wheel end torque TTarCalculating a target gear ratio i from the current engine torqueTar。
The target transmission ratio i is calculated in a calculation moduleTarThereafter, the determination unit determines a target gear G for the vehicle 1TarI.e. to bring the vehicle 1 to the target gear ratio iTarThe gear position of (2). The determination module 38 determines the target gear G by means of a gear ratio modelTarAnd shifting the target gear GTarTo the gear shift system 300 of the vehicle 1, for example, to an automatic Transmission Control Unit (TCU)310 of the gear shift system 300, so that the automatic transmission control unit 310 controls the automatic transmission of the vehicle 1 to shift (lower) from the current gear to the target gear GTar。
The gear ratio model is a function representing the correspondence between gear ratio and gear of the automatic transmission of the vehicle 1 during a gear shift. The function may be derived by physical experiments, theoretical calculations or simulation fits, and combinations thereof. For example, through real vehicle testing, multiple sets of data of the transmission ratio and the gear during the gear shifting process are measured, and then the corresponding relation between the two (for example, the transmission ratio-gear curve) is obtained by adopting a mathematical calculation or curve fitting mode. A ratio difference is calculated based on the target and current ratios, and it is determined on the ratio-gear curve to which gear the target ratio needs to be changed (reduced) from the current gear.
Accurately determining 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 shift, the transmission ratio may have a continuously changing (or irregularly stepped) course, during which the ratio-gear correspondence does not fully comply with the predetermined correspondence. Therefore, it is significant to measure the transmission ratio corresponding to each gear during shifting by real vehicles and to fit a transmission ratio-gear curve during shifting by a mathematical model, thereby obtaining a transmission ratio model.
In addition, the vehicle 1 may have a regenerative braking system (e.g., RBS). The recovery module 39 of the deceleration control unit 30 may generate a command instructing to recover the reuse energy and send the command to the regenerative braking system. The command is used to instruct the regenerative braking system to recover and reuse kinetic energy during the gear shifting deceleration, for example, to convert the kinetic energy into electric energy to be supplied to the battery or the electric equipment of the vehicle 1.
Fig. 4 shows a deceleration control method 400 for driving assistance to the vehicle 1 according to one possible embodiment of the invention. This method may be implemented by the deceleration control unit 30 or by the driving assistance system 100. Therefore, the above description regarding the deceleration control unit 30 and the driving assist system 100 is also applicable here.
Referring to fig. 4, in step S410, the acquisition module 32 acquires a deceleration request and parameter values for subsequent operations.
Next, in step S420, the determination module 34 determines whether the target deceleration is equal to or less than a deceleration threshold.
If the determination module 34 determines "no" in step S420, the method 400 proceeds to step S430. In step S430, the determination module 34 activates the deceleration control module of the driving stability system so as to perform the braking manipulation.
If 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.
If the determination module 34 determines "no" in step S440, the method 400 proceeds to step S430. In step S430, the determination module 34 activates the deceleration control module of the driving stability system so as to perform the braking manipulation.
If the determination module 34 determines "yes" in step S440, the 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-S495 are performed in order.
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 the 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 method 400, steps S420 and S440 may be performed in any order or simultaneously.
According to the technical scheme of the invention, whether the control logic for gear reduction is suitable for being adopted is judged based on the working condition of the vehicle, so that the gear reduction control logic can be started under the condition that the working condition of the vehicle is suitable. And starting the braking deceleration control logic under the condition that the working condition of the vehicle is not suitable for downshift deceleration. Thus, the control logic of the two aspects can be adapted. According to the control logic of the 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 feelings caused by frequent active intervention braking of a driving stability system of the vehicle are avoided. In addition, by recycling and reusing kinetic energy in the deceleration process, the vehicle driver is supported in a resource-saving driving mode.
While the foregoing describes certain embodiments, these embodiments are presented by way of example only, and are not intended to limit the scope of the present invention. The appended claims and their equivalents are intended to cover all such modifications, substitutions and changes as may be made within the scope and spirit of the present invention.

Claims (12)

1. 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 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 determination module determines whether the target deceleration is equal to or less than a deceleration threshold, and in the case where the determination result is affirmative, the calculation module calculates a target gear ratio that causes the vehicle to reach the target deceleration based on a difference between the target deceleration and a current deceleration; and is
The determination module determines a target gear that causes the vehicle to reach the target gear ratio based on a difference between the 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, wherein the gear ratio model is a function representing a correspondence between the gear ratio and a gear of the automatic transmission during a gear shift.
2. The deceleration control unit according to claim 1, wherein the gear ratio model is obtained by processing sets of data based on experimentally measured sets of data of gear ratio and gear position during the gear shift by at least one of theoretical calculation and curve fitting.
3. The deceleration control unit according to claim 1 or 2, wherein in a case where the determination result is negative, the 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 a braking manipulation.
4. The deceleration control unit according to any one of claims 1 to 3, wherein the deceleration threshold value corresponds to a deceleration value that the automatic transmission lowers by two or more gears so that the vehicle achieves.
5. The deceleration control unit according to any one of claims 1 to 4, wherein the acquisition module acquires a gradient value of a road on which the vehicle is running;
the judging module judges whether the acquired gradient value is less than or equal to a gradient threshold value;
in the case that the judgment result is positive, allowing the operation of the calculation module and the determination module;
in the case where the determination result is negative, the 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 a braking manipulation.
6. The deceleration control unit according to any one of claims 1 to 5, wherein 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 from the potential collision object in a case where there is a potential collision object in front of the vehicle; and is
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 in a case where there is no potential collision object in front of the vehicle.
7. The deceleration control unit according to any one of claims 1 to 6, wherein the calculation module calculates a target deceleration in response to a deceleration request and based on the following formula in a case where there is a potential collision object in front of the vehicle: a isTar(V1-V2) ^2/2S, wherein, aTarTarget deceleration of (V1-V2), and S are the relative speed and relative distance between the vehicle and the preceding potential collision object, respectively; and is
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 the following formula: a isTar(Vset-V1)/T, wherein aTarVset 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, for the target deceleration.
8. The deceleration control unit according to any one of claims 1 to 7, wherein the calculation module calculates the target gear ratio based on a difference between a target deceleration and a current deceleration includes:
calculating an increased braking force required 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 wheel 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 engine torque.
9. The deceleration control unit according to any one of claims 1 to 8, 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 conversion of the kinetic energy into electric energy for supply to a battery or a consumer of the vehicle.
10. A drive assist system for a vehicle, the vehicle being a vehicle with an automatic transmission, the drive assist system comprising:
a forward sensor for sensing travel data of the vehicle;
a controller electrically connected to the forward sensor and communicatively connected to an engine management system and a driveline of the vehicle via a vehicle communication bus, the controller comprising a deceleration control unit according to any one of claims 1 to 9, 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 the driveline to achieve a target deceleration.
11. The driving assistance system according to claim 9, wherein the forward sensor includes at least a radar sensor; and is
The driving assistance system is an adaptive cruise control system or a radar system or a combination of both of the vehicle.
12. A deceleration control method for a vehicle for assisting driving of the vehicle, the vehicle being a vehicle with an automatic transmission, optionally the method being implemented by means of a deceleration control unit according to any of claims 1-9 and/or a driving assistance system according to any of claims 10-11, the method comprising:
acquiring a deceleration request and running data of the vehicle, wherein the running data at least comprises a current deceleration and a current transmission ratio;
calculating a target deceleration of the vehicle in response to the deceleration request;
determining whether the target deceleration is less than or equal to a deceleration threshold;
in the case where the determination result is affirmative, calculating a target gear ratio that causes the vehicle to reach a target deceleration, based on a difference between the target deceleration and a current deceleration;
determining a target gear for enabling the vehicle to reach the target gear ratio based on a difference between the target gear ratio and a current gear ratio and a gear ratio model, wherein the gear ratio model is a function representing a corresponding relation between the gear ratio and a gear of the automatic transmission in a gear shifting process, and the function is obtained through at least one of physical experiments, theoretical calculation and simulation fitting; and
transmitting the target gear to an automatic transmission control unit of the vehicle.
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