CN110371117B - Vehicle braking deceleration determining method and device and automobile - Google Patents

Vehicle braking deceleration determining method and device and automobile Download PDF

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CN110371117B
CN110371117B CN201910572102.3A CN201910572102A CN110371117B CN 110371117 B CN110371117 B CN 110371117B CN 201910572102 A CN201910572102 A CN 201910572102A CN 110371117 B CN110371117 B CN 110371117B
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vehicle
current
braking deceleration
determining
mode
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CN110371117A (en
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张欢庆
周增碧
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Chongqing Changan Automobile Software Technology Co ltd
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Chongqing Changan Automobile 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, or advanced driver assistance systems for ensuring comfort, stability and safety or drive control systems for propelling or retarding the vehicle
    • B60W30/14—Adaptive cruise control
    • 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, or advanced driver assistance systems for ensuring comfort, stability and safety or drive control systems for propelling or retarding the vehicle
    • B60W30/14—Adaptive cruise control
    • B60W30/143—Speed control
    • 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
    • B60W40/00—Estimation or calculation of non-directly measurable driving parameters for road vehicle drive control systems not related to the control of a particular sub unit, e.g. by using mathematical models
    • 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
    • B60W40/00—Estimation or calculation of non-directly measurable driving parameters for road vehicle drive control systems not related to the control of a particular sub unit, e.g. by using mathematical models
    • B60W40/10—Estimation or calculation of non-directly measurable driving parameters for road vehicle drive control systems not related to the control of a particular sub unit, e.g. by using mathematical models related to vehicle motion
    • 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
    • B60W40/00—Estimation or calculation of non-directly measurable driving parameters for road vehicle drive control systems not related to the control of a particular sub unit, e.g. by using mathematical models
    • B60W40/10—Estimation or calculation of non-directly measurable driving parameters for road vehicle drive control systems not related to the control of a particular sub unit, e.g. by using mathematical models related to vehicle motion
    • B60W40/105—Speed

Abstract

The invention relates to a method and a device for determining vehicle braking deceleration and an automobile, and aims to solve the problem that riding experience is poor due to unstable braking deceleration of a vehicle in an automatic driving state in the prior art. The vehicle braking deceleration determination method includes: determining the current driving mode of the vehicle when the vehicle is in an automatic driving state; when the current running mode of the vehicle is the cruise mode, determining the target braking deceleration of the vehicle at the current moment according to the relevant running parameters of the vehicle; when the current running mode of the vehicle is a following mode, determining the target braking deceleration of the vehicle at the current moment according to the related running parameters of the vehicle and the preceding vehicle; the front vehicle is a vehicle which is positioned in front of the lane where the vehicle runs and the longitudinal distance between the front vehicle and the vehicle is within a preset distance range.

Description

Vehicle braking deceleration determining method and device and automobile
Technical Field
The invention relates to the field of vehicle-mounted data storage, in particular to a method and a device for determining vehicle braking deceleration and an automobile.
Background
In the development of the longitudinal function of the automatic driving, people hope that the vehicle can keep the same speed as the front vehicle and keep a more ideal safe distance. When the current vehicle state is stable, the two conditions are easy to satisfy. When the current vehicle state changes (such as acceleration, deceleration, cut-in and cut-out, and the like), how to control the accelerator and the brake of the automatic driving vehicle to adapt to the change of the current vehicle state is a difficulty of longitudinal development of automatic driving. In particular, the braking process should take into account, in addition to safety issues, also ride comfort issues. A braking deceleration planning method that can ensure driving safety and give consideration to riding comfort is particularly important.
Disclosure of Invention
The invention aims to provide a method and a device for determining vehicle braking deceleration and an automobile, and aims to solve the problem that riding experience is poor due to unstable braking deceleration of a vehicle in an automatic driving state in the prior art.
The technical scheme of the invention is as follows:
the invention provides a vehicle braking deceleration determining method, which comprises the following steps:
determining the current driving mode of the vehicle when the vehicle is in an automatic driving state;
when the current running mode of the vehicle is the cruise mode, determining the target braking deceleration of the vehicle at the current moment according to the relevant running parameters of the vehicle;
when the current running mode of the vehicle is a following mode, determining the target braking deceleration of the vehicle at the current moment according to the related running parameters of the vehicle and the preceding vehicle; the front vehicle is a vehicle which is positioned in front of the lane where the vehicle runs and the longitudinal distance between the front vehicle and the vehicle is within a preset distance range.
Preferably, the step of determining the current driving mode of the host vehicle includes:
judging whether a front vehicle with a longitudinal distance from the vehicle within a preset distance range exists in front of a lane where the vehicle runs;
if not, determining that the current running mode of the vehicle is a cruise mode;
if yes, judging whether the current actual speed of the front vehicle is greater than the current actual speed of the vehicle;
if so, determining that the current running mode of the vehicle is a cruise mode; otherwise, the current driving mode of the vehicle is determined to be the following mode.
Preferably, when the current running mode of the host vehicle is the cruise mode, the relevant running parameters of the host vehicle include a current actual vehicle speed Vh and a desired vehicle speed Vt of the host vehicle, and the step of determining the target braking deceleration of the host vehicle at the current time based on the relevant running parameters of the host vehicle includes:
according to the current actual speed Vh and the expected speed Vt of the vehicle, the target braking deceleration At corresponding to the current actual speed Vh and the expected speed Vt is found out from a predetermined comparison table1。
Preferably, the step of determining the target braking deceleration of the host vehicle at the current time based on the relevant travel parameters of the host vehicle and the preceding vehicle when the current travel mode of the host vehicle is the following mode includes:
determining the current running state of the vehicle according to the relevant running parameters of the vehicle and the relevant running parameters of the front vehicle;
determining initial values of braking deceleration of the vehicle in different running states according to relevant running parameters of the vehicle and a preceding vehicle;
the determined initial value of the braking deceleration is smoothed, and the target braking deceleration of the vehicle at the current time is determined.
Preferably, the step of determining the initial braking deceleration value of the vehicle in different driving states according to the driving parameters related to the vehicle and the preceding vehicle comprises:
if the current running state of the vehicle is a transition control state, according to the expected vehicle speed of the vehicle, the expected following distance of the vehicle, the current actual vehicle speed of the vehicle and the relative distance between the vehicle and the front vehicle, passing through a formula:
Figure GDA0002545657940000021
determining the initial value At of braking deceleration of the vehicle in the transient control state2Wherein, Vt is the expected speed of the vehicle, Vh is the current actual speed of the vehicle, Dr is the relative distance between the vehicle and the front vehicle, and Dt is the expected following distance of the vehicle;
if the current running state of the vehicle is a normal following state, according to the expected speed of the vehicle, the minimum safe distance between the vehicle and the front vehicle, the current actual vehicle h of the vehicle and the relative distance between the vehicle and the front vehicle, passing through a formula:
Figure GDA0002545657940000022
determining the initial value At of braking deceleration of the vehicle under the normal following state3Wherein D isMinSafeThe minimum safe distance between the host vehicle and the front vehicle is set on the host vehicle, Vh is the current actual speed of the host vehicle, Vt is the expected speed of the host vehicle, and Dr is the relative distance between the host vehicle and the front vehicle.
Preferably, the step of smoothing the determined initial value of the braking deceleration and determining the target braking deceleration of the host vehicle at the current time includes:
comparing the initial brake deceleration value At _ raw with a preset brake deceleration upper limit value Gain1, and outputting a first parameter value At _ upper with a larger value;
comparing the output first parameter value At _ upper with the brake deceleration output value At _ delay output by the host vehicle At the previous moment, and judging whether the brake deceleration output value At _ delay is greater than or equal to the first parameter value At _ upper;
if the current braking deceleration is larger than or equal to the target braking deceleration, outputting the first parameter value At _ upper as the target braking deceleration of the vehicle At the current moment;
comparing the initial brake deceleration value At _ raw with a preset lower brake deceleration limit value Gain2, and outputting a second parameter value At _ lower with a smaller value;
if the brake deceleration output value At _ delay is smaller than the first parameter value At _ upper, outputting the brake deceleration output value At _ delay output by the host vehicle At the previous moment, and judging whether the brake deceleration output value At _ delay is smaller than the second parameter value At _ lower;
if the current braking deceleration is smaller than the target deceleration, outputting the second parameter value At _ lower as the target braking deceleration of the vehicle At the current moment; on the contrary, the brake deceleration output value At _ delay output by the host vehicle At the previous time is output as the target brake deceleration of the host vehicle At the current time.
Preferably, when the current driving mode of the vehicle is a following mode, the method further includes:
calculating the collision duration required by the collision between the vehicle and the front vehicle according to the relative distance between the vehicle and the front vehicle and the relative speed between the vehicle and the front vehicle;
and determining the braking deceleration change slope of the braking deceleration of the vehicle in each unit collision time length from a preset comparison relation table according to the calculated collision time length, and controlling the vehicle to adjust the actual braking deceleration of the vehicle according to the determined braking deceleration change slope until the target braking deceleration is adjusted.
According to another aspect of the present invention, there is also provided a vehicle braking deceleration determination apparatus comprising:
the first determination module is used for determining the current running mode of the vehicle when the vehicle is in an automatic driving state;
the second determining module is used for determining the target braking deceleration of the vehicle at the current moment according to the relevant running parameters of the vehicle when the current running mode of the vehicle is the cruise mode;
the third determining module is used for determining the target braking deceleration of the vehicle at the current moment according to the related running parameters of the vehicle and the front vehicle when the current running mode of the vehicle is the following mode; the front vehicle is a vehicle which is positioned in front of the lane where the vehicle runs and the longitudinal distance between the front vehicle and the vehicle is within a preset distance range.
Preferably, the first determining module comprises:
the first judging unit is used for judging whether a front vehicle with the longitudinal distance from the vehicle within a preset distance range exists in front of the lane where the vehicle runs;
the first determining unit is used for determining that the current running mode of the vehicle is a cruise mode if the current running mode does not exist;
the second judgment unit is used for judging whether the current actual speed of the front vehicle is greater than the current actual speed of the vehicle if the current actual speed of the front vehicle is greater than the current actual speed of the vehicle;
the second determining unit is used for determining that the current running mode of the vehicle is the cruise mode if the current running mode is larger than the cruise mode;
and the third determining unit is used for determining that the current running mode of the vehicle is the following mode if the current running mode is not the following mode.
Preferably, when the current driving mode of the host vehicle is the cruise mode, the relevant driving parameters of the host vehicle include the current actual vehicle speed and the expected vehicle speed of the host vehicle, and the second determining module includes:
a search unit for searching a target braking deceleration At corresponding to the current actual vehicle speed and the expected vehicle speed from a predetermined comparison table according to the current actual vehicle speed and the expected vehicle speed of the vehicle1。
Preferably, when the current driving mode of the host vehicle is a following mode, the third determining module includes:
the fourth determining unit is used for determining the current running state of the vehicle according to the relevant running parameters of the vehicle and the relevant running parameters of the front vehicle;
a fifth determining unit, configured to determine initial values of braking deceleration of the vehicle in different driving states according to the related driving parameters of the vehicle and the preceding vehicle;
and a sixth determining unit configured to perform smoothing processing on the determined initial value of the braking deceleration and determine a target braking deceleration of the host vehicle at the current time.
Preferably, the fifth determination unit includes:
the first determining subunit is configured to, if the current driving state of the host vehicle is a transition control state, pass through a formula according to an expected vehicle speed of the host vehicle, an expected following distance of the host vehicle, a current actual vehicle speed of the host vehicle, and a relative distance between the host vehicle and a preceding vehicle:
Figure GDA0002545657940000041
determining the initial value At of braking deceleration of the vehicle in the transient control state2Wherein, Vt is the expected speed of the vehicle, Vh is the current actual speed of the vehicle, Dr is the relative distance between the vehicle and the front vehicle, and Dt is the expected following distance of the vehicle;
a second determining subunit, configured to, if the current driving state of the host vehicle is a normal following state, pass through a formula according to an expected vehicle speed of the host vehicle, a minimum safe distance between the host vehicle and a preceding vehicle, a current actual vehicle speed of the host vehicle, and a relative distance between the host vehicle and the preceding vehicle:
Figure GDA0002545657940000042
determining the initial value At of braking deceleration of the vehicle under the normal following state3Wherein D isMinSafeIs the minimum safety distance between the vehicle and the front vehicle, and Vh is the vehicleThe current actual vehicle speed, Vt, is the desired vehicle speed of the host vehicle, and Dr is the relative distance between the host vehicle and the preceding vehicle.
Preferably, the sixth determination unit includes:
the first output subunit is used for comparing the initial brake deceleration value At _ raw with a preset brake deceleration upper limit value Gain1 and outputting a first parameter value At _ upper with a larger value;
a first judging subunit, configured to compare the output first parameter value At _ upper with the brake deceleration output value At _ delay output by the host vehicle At the previous time, and judge whether the brake deceleration output value At _ delay is greater than or equal to the first parameter value At _ upper;
the second output subunit is used for outputting the first parameter value At _ upper as the target braking deceleration of the vehicle At the current moment if the first parameter value At _ upper is larger than or equal to the target braking deceleration;
a third output subunit, configured to compare the initial brake deceleration value At _ raw with a predetermined lower brake deceleration limit value Gain2, and output a second parameter value At _ lower having a smaller value;
a second determining subunit, configured to, if the brake deceleration output value At _ delay is smaller than the first parameter value At _ upper, output the brake deceleration output value At _ delay output by the host vehicle At the previous time, and determine whether the brake deceleration output value At _ delay is smaller than the second parameter value At _ lower;
a fourth output subunit, configured to output the second parameter value At _ lower as a target braking deceleration of the host vehicle At the current time if the second parameter value At _ lower is smaller than the first parameter value; on the contrary, the brake deceleration output value At _ delay output by the host vehicle At the previous time is output as the target brake deceleration of the host vehicle At the current time.
Preferably, when the current running mode of the host vehicle is a following mode, the apparatus further includes:
the calculation module is used for calculating the collision duration required by the collision between the vehicle and the front vehicle according to the relative distance between the vehicle and the front vehicle and the relative speed between the vehicle and the front vehicle;
and the control module is used for determining the braking deceleration change slope of the braking deceleration of the vehicle in each unit collision time length from a preset comparison table according to the calculated collision time length, and controlling the vehicle to adjust the actual braking deceleration of the vehicle according to the determined braking deceleration change slope until the target braking deceleration is adjusted.
According to another aspect of the present invention, there is also provided an automobile including the vehicle braking deceleration determining apparatus described above.
The invention has the beneficial effects that:
when the state of the front vehicle changes, the problem of irregularity in the braking process of the vehicle can be effectively solved. When the state of the front vehicle changes, the driving state of the front vehicle is divided into three types, namely a normal vehicle following state and a transition control state under a cruise mode and a vehicle following mode according to related driving parameters of the front vehicle and the front vehicle, the target braking deceleration capable of enabling the front vehicle to brake stably under the three conditions is calculated respectively, and finally the target braking deceleration is integrated and optimized and then sent to a brake actuator controller (ESP), so that the riding experience of the front vehicle during following braking when the state of the front vehicle changes can be improved.
Drawings
FIG. 1 is a flow chart of a method of the present invention;
FIG. 2 is a flowchart of step 101;
FIG. 3 is a flowchart of step 103;
FIG. 4 is a flowchart of step 303;
FIG. 5 is a block diagram of the apparatus of the present invention.
Detailed Description
Exemplary embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. While exemplary embodiments of the invention are shown in the drawings, it should be understood that the invention can be embodied in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.
Referring to fig. 1, the present invention provides a vehicle braking deceleration determination method including:
in step 101, when the vehicle is in the automatic driving state, the current driving mode of the vehicle is determined.
The self-driving state of the vehicle means that the accelerator and the brake of the vehicle are controlled by the vehicle independently, and a driver does not need to participate in the driving control of the vehicle.
The current driving mode of the vehicle comprises a following mode and a cruising mode, and whether the current driving mode of the vehicle is the following mode or the cruising mode is judged mainly according to whether a front vehicle exists in front of a lane where the vehicle is located and the relative distance between the front vehicle and the vehicle.
Specifically, as shown in fig. 2, the step 101 includes:
step 201, judging whether a front vehicle with a longitudinal distance from the vehicle within a preset distance range exists in front of a lane where the vehicle runs; the predetermined distance range is, for example, 200m, 150m, or 300 m.
Step 202, if the current driving mode of the vehicle is not the cruise mode, determining that the current driving mode of the vehicle is the cruise mode;
step 203, if yes, judging whether the current actual speed of the front vehicle is greater than the current actual speed of the vehicle;
step 204, if the current driving mode is larger than the cruise mode, determining that the current driving mode of the vehicle is the cruise mode; otherwise, the current driving mode of the vehicle is determined to be the following mode.
And 102, when the current running mode of the vehicle is the cruise mode, determining the target braking deceleration of the vehicle at the current time according to the relevant running parameters of the vehicle.
The step 102 of determining the target braking deceleration of the host vehicle at the current time based on the relevant travel parameters of the host vehicle includes:
according to the current actual speed and the expected speed of the vehicle, the current actual speed and the period of the vehicle are found out from a preset comparison relation tableTarget braking deceleration At corresponding to the desired vehicle speed1。
The comparison relation table records the corresponding relation among the current actual speed of the vehicle, the expected speed and the target braking deceleration, and the corresponding specific numerical value in the comparison relation table is determined by carrying out an actual vehicle test.
Step 103, when the current running mode of the vehicle is a following mode, determining the target braking deceleration of the vehicle at the current time according to the relevant running parameters of the vehicle and the preceding vehicle; the front vehicle is a vehicle which is positioned in front of the lane where the vehicle runs and the longitudinal distance between the front vehicle and the vehicle is within a preset distance range.
When the current driving mode of the vehicle is the following mode, the driving parameters related to the vehicle and the preceding vehicle include: the vehicle-mounted system comprises a current actual vehicle speed of the vehicle, a desired vehicle speed of the vehicle, a relative distance between the vehicle and a preceding vehicle, a relative vehicle speed between the vehicle and the preceding vehicle, a minimum safe distance between the vehicle and the preceding vehicle, and a current actual vehicle speed of the preceding vehicle. The relevant driving parameters related to the vehicle itself are obtained by extracting data from a relevant controller of the vehicle, and the relative distance and the relative speed between the vehicle and the preceding vehicle are detected by a high-precision sensor such as a millimeter wave radar.
Specifically, referring to fig. 3, step 103 includes:
step 301, determining the current driving state of the vehicle according to the related driving parameters of the vehicle and the related driving parameters of the front vehicle; under the following mode, the vehicle includes 2 driving states, namely a normal following state and a transition control state, wherein the transition control state is a state which prevents the vehicle from influencing the riding experience due to too fast change of the braking deceleration of the vehicle under the condition that the expected vehicle speed of the vehicle in the current detection period is suddenly changed to be smaller than the expected vehicle speed detected in the last detection period and the current actual vehicle speed of the vehicle. The normal vehicle following state refers to a state that the vehicle enters under the condition that the current actual vehicle speed of the preceding vehicle is greater than or equal to the current actual vehicle speed of the vehicle and the relative distance between the vehicle and the preceding vehicle is greater than or equal to the expected vehicle following distance of the vehicle.
And under the normal following mode, judging the specific running load of the vehicle according to the conditions which are required to be met by the transition control state and the normal following state respectively.
Step 302, according to the relevant running parameters of the vehicle and the front vehicle, the initial braking deceleration value of the vehicle in different running states is determined.
Specifically, step 302 includes:
if the current running state of the vehicle is a transition control state, according to the expected vehicle speed of the vehicle, the expected following distance of the vehicle, the current actual vehicle speed of the vehicle and the relative distance between the vehicle and the front vehicle, passing through a formula:
Figure GDA0002545657940000081
determining the initial value At of braking deceleration of the vehicle in the transient control state2Wherein, Vt is the expected speed of the vehicle, Vh is the current actual speed of the vehicle, Dr is the relative distance between the vehicle and the front vehicle, and Dt is the expected following distance of the vehicle;
if the current running state of the vehicle is a normal following state, according to the expected vehicle speed of the vehicle, the minimum safe distance between the vehicle and the front vehicle, the current actual vehicle speed of the vehicle and the relative distance between the vehicle and the front vehicle, passing through a formula:
Figure GDA0002545657940000082
determining the initial value At of braking deceleration of the vehicle under the normal following state3Wherein D isMinSafeThe minimum safe distance between the host vehicle and the front vehicle is set on the host vehicle, Vh is the current actual speed of the host vehicle, Vt is the expected speed of the host vehicle, and Dr is the relative distance between the host vehicle and the front vehicle.
Step 303 is to smooth the determined initial value of the braking deceleration and determine the target braking deceleration of the vehicle at the current time.
Specifically, referring to fig. 4, step 303 includes:
step 401, comparing the initial brake deceleration value At _ raw with a predetermined brake deceleration upper limit value Gain1, and outputting a first parameter value At _ upper with a larger value;
step 402, comparing the output first parameter value At _ upper with the brake deceleration output value At _ delay output by the host vehicle At the last moment, and judging whether the brake deceleration output value At _ delay is greater than or equal to the first parameter value At _ upper;
step 403, if the current braking deceleration is larger than or equal to the target braking deceleration, outputting the first parameter value At _ upper as the target braking deceleration of the vehicle At the current moment;
step 404, comparing the initial braking deceleration value At _ raw with a predetermined lower braking deceleration limit value Gain2, and outputting a second parameter value At _ lower with a smaller value;
step 405, if the brake deceleration output value At _ delay is smaller than the first parameter value At _ upper, outputting the brake deceleration output value At _ delay output by the host vehicle At the previous moment;
step 406, determining whether the brake deceleration output value At _ delay is smaller than the second parameter value At _ lower;
step 407, if the current braking deceleration is smaller than the target deceleration, outputting the second parameter value At _ lower as the target braking deceleration of the vehicle At the current moment;
in step 408, otherwise, the brake deceleration output value At _ delay output by the host vehicle At the previous time is output as the target brake deceleration of the host vehicle At the current time.
As shown in fig. 4, the output At represents the target braking deceleration of the host vehicle At the current time, and in order to facilitate calculation of the target braking deceleration of the host vehicle At the next time, after the target braking deceleration of the host vehicle At the current time is determined, the current target braking deceleration At is output to a delay function, that is, step 409 is performed, and the value output by the delay function is the target braking deceleration output value At _ delay of the host vehicle At the previous time when the target braking deceleration smoothing processing At the current time is performed next time.
Preferably, as shown in fig. 1, when the current driving mode of the host vehicle is a following mode, the method further includes:
and 104, calculating the collision duration required by the collision of the vehicle and the front vehicle according to the relative distance between the vehicle and the front vehicle and the relative speed between the vehicle and the front vehicle, wherein the collision duration is specifically the ratio of the relative distance between the vehicle and the front vehicle and the loudness speed between the vehicle and the front vehicle.
And 105, determining the braking deceleration change slope of the braking deceleration of the vehicle in each unit collision time length from a preset comparison relation table according to the calculated collision time length, and controlling the vehicle to adjust the actual braking deceleration of the vehicle according to the determined braking deceleration change slope until the target braking deceleration is adjusted. Specifically, the brake actuator controller ESP is subjected to brake deceleration modulation.
The embodiment of the invention can effectively solve the problem of irregularity in the braking process of the vehicle when the state of the front vehicle changes. When the state of the front vehicle changes, the driving state of the front vehicle is divided into three types, namely a normal following state and a transition control state under a cruise mode and a following mode according to related driving parameters of the front vehicle and the front vehicle, a target braking target deceleration which can enable the front vehicle to brake stably under the three conditions is calculated respectively, and finally the target braking target deceleration is integrated and optimized and then sent to a brake actuator controller (ESP), so that the riding experience of the front vehicle during following braking can be improved when the state of the front vehicle changes.
Referring to fig. 5, according to another aspect of the present invention, there is also provided a vehicle braking deceleration determining apparatus including:
a first determining module 501, configured to determine a current driving mode of the host vehicle when the host vehicle is in an automatic driving state;
a second determining module 502, configured to determine, according to the relevant driving parameters of the host vehicle, a target braking deceleration of the host vehicle at the current time when the current driving mode of the host vehicle is the cruise mode;
a third determining module 503, configured to determine, according to the related driving parameters of the host vehicle and the preceding vehicle, a target braking deceleration of the host vehicle at the current time when the current driving mode of the host vehicle is the following mode; the front vehicle is a vehicle which is positioned in front of the lane where the vehicle runs and the longitudinal distance between the front vehicle and the vehicle is within a preset distance range.
Preferably, the first determining module comprises:
the first judging unit is used for judging whether a front vehicle with the longitudinal distance from the vehicle within a preset distance range exists in front of the lane where the vehicle runs;
the first determining unit is used for determining that the current running mode of the vehicle is a cruise mode if the current running mode does not exist;
the second judgment unit is used for judging whether the current actual speed of the front vehicle is greater than the current actual speed of the vehicle if the current actual speed of the front vehicle is greater than the current actual speed of the vehicle;
the second determining unit is used for determining that the current running mode of the vehicle is the cruise mode if the current running mode is larger than the cruise mode;
and the third determining unit is used for determining that the current running mode of the vehicle is the following mode if the current running mode is not the following mode.
Preferably, when the current running mode of the host vehicle is the cruise mode, the relevant running parameters of the host vehicle include a current actual vehicle speed Vh and a desired vehicle speed Vt of the host vehicle, and the second determining module includes:
a search unit for searching a target braking deceleration At corresponding to the current actual vehicle speed Vh and the desired vehicle speed Vt from a predetermined comparison table according to the current actual vehicle speed Vh and the desired vehicle speed Vt of the host vehicle1。
Preferably, when the current driving mode of the host vehicle is a following mode, the third determining module includes:
the fourth determining unit is used for determining the current running state of the vehicle according to the relevant running parameters of the vehicle and the relevant running parameters of the front vehicle;
a fifth determining unit, configured to determine initial values of braking deceleration of the vehicle in different driving states according to the related driving parameters of the vehicle and the preceding vehicle;
and a sixth determining unit configured to perform smoothing processing on the determined initial value of the braking deceleration and determine a target braking deceleration of the host vehicle at the current time.
Preferably, the fifth determination unit includes:
the first determining subunit is configured to, if the current driving state of the host vehicle is a transition control state, pass through a formula according to an expected vehicle speed of the host vehicle, an expected following distance of the host vehicle, a current actual vehicle speed of the host vehicle, and a relative distance between the host vehicle and a preceding vehicle:
Figure GDA0002545657940000101
determining the initial value At of braking deceleration of the vehicle in the transient control state2Wherein, Vt is the expected speed of the vehicle, Vh is the current actual speed of the vehicle, Dr is the relative distance between the vehicle and the front vehicle, and Dt is the expected following distance of the vehicle;
a second determining subunit, configured to, if the current driving state of the host vehicle is a normal following state, pass through a formula according to an expected vehicle speed of the host vehicle, a minimum safe distance between the host vehicle and a preceding vehicle, a current actual vehicle speed of the host vehicle, and a relative distance between the host vehicle and the preceding vehicle:
Figure GDA0002545657940000111
determining the initial value At of braking deceleration of the vehicle under the normal following state3Wherein D isMinSafeThe minimum safe distance between the host vehicle and the front vehicle is set on the host vehicle, Vh is the current actual speed of the host vehicle, Vt is the expected speed of the host vehicle, and Dr is the relative distance between the host vehicle and the front vehicle.
Preferably, the sixth determination unit includes:
the first output subunit is used for comparing the initial brake deceleration value At _ raw with a preset brake deceleration upper limit value Gain1 and outputting a first parameter value At _ upper with a larger value;
a first judging subunit, configured to compare the output first parameter value At _ upper with the brake deceleration output value At _ delay output by the host vehicle At the previous time, and judge whether the brake deceleration output value At _ delay is greater than or equal to the first parameter value At _ upper;
the second output subunit is used for outputting the first parameter value At _ upper as the target braking deceleration of the vehicle At the current moment if the first parameter value At _ upper is larger than or equal to the target braking deceleration;
a third output subunit, configured to compare the initial brake deceleration value At _ raw with a predetermined lower brake deceleration limit value Gain2, and output a second parameter value At _ lower having a smaller value;
a second determining subunit, configured to, if the brake deceleration output value At _ delay is smaller than the first parameter value At _ upper, output the brake deceleration output value At _ delay output by the host vehicle At the previous time, and determine whether the brake deceleration output value At _ delay is smaller than the second parameter value At _ lower;
a fourth output subunit, configured to output the second parameter value At _ lower as a target braking deceleration of the host vehicle At the current time if the second parameter value At _ lower is smaller than the first parameter value; on the contrary, the brake deceleration output value At _ delay output by the host vehicle At the previous time is output as the target brake deceleration of the host vehicle At the current time.
Preferably, when the current running mode of the host vehicle is a following mode, the apparatus further includes:
the calculation module is used for calculating the collision duration required by the collision between the vehicle and the front vehicle according to the relative distance between the vehicle and the front vehicle and the relative speed between the vehicle and the front vehicle;
and the control module is used for determining the braking deceleration change slope of the braking deceleration of the vehicle in each unit collision time length from a preset comparison table according to the calculated collision time length, and controlling the vehicle to adjust the actual braking deceleration of the vehicle according to the determined braking deceleration change slope until the target braking deceleration is adjusted.
The device in the embodiment of the invention is a device corresponding to the method one by one, and can achieve the same technical effect as the method, namely, when the state of the front vehicle changes, the device can effectively solve the problem of irregularity in the braking process of the vehicle. When the state of the front vehicle changes, the driving state of the front vehicle is divided into three types, namely a normal following state and a transition control state under a cruise mode and a following mode according to related driving parameters of the front vehicle and the front vehicle, a target braking target deceleration which can enable the front vehicle to brake stably under the three conditions is calculated respectively, and finally the target braking target deceleration is integrated and optimized and then sent to a brake actuator controller (ESP), so that the riding experience of the front vehicle during following braking can be improved when the state of the front vehicle changes.
According to another aspect of the present invention, there is also provided an automobile including the vehicle braking deceleration determining apparatus described above.

Claims (7)

1. A vehicle braking deceleration determination method, characterized by comprising:
determining the current driving mode of the vehicle when the vehicle is in an automatic driving state;
when the current running mode of the vehicle is the cruise mode, determining the target braking deceleration of the vehicle at the current moment according to the relevant running parameters of the vehicle;
when the current running mode of the vehicle is a following mode, determining the target braking deceleration of the vehicle at the current moment according to the related running parameters of the vehicle and the preceding vehicle; the front vehicle is a vehicle which is positioned in front of a lane where the vehicle runs and the longitudinal distance between the front vehicle and the vehicle is within a preset distance range;
when the current running mode of the vehicle is the following mode, the step of determining the target braking deceleration of the vehicle at the current moment according to the relevant running parameters of the vehicle and the preceding vehicle is specifically as follows:
determining the current running state of the vehicle according to the relevant running parameters of the vehicle and the relevant running parameters of the front vehicle;
if the current running state of the vehicle is a transition control state, according to the expected vehicle speed of the vehicle, the expected following distance of the vehicle, the current actual vehicle speed of the vehicle and the relative distance between the vehicle and the front vehicle, passing through a formula:
Figure FDA0002545657930000011
determining the initial value At of braking deceleration of the vehicle in the transient control state2Wherein, Vt is the expected speed of the vehicle, Vh is the current actual speed of the vehicle, Dr is the relative distance between the vehicle and the front vehicle, and Dt is the expected following distance of the vehicle;
if the current running state of the vehicle is a normal following state, according to the expected vehicle speed of the vehicle, the minimum safe distance between the vehicle and the front vehicle, the current actual vehicle speed of the vehicle and the relative distance between the vehicle and the front vehicle, passing through a formula:
Figure FDA0002545657930000012
determining the initial value At of braking deceleration of the vehicle under the normal following state3Wherein D isMinSafeThe minimum safe distance between the host vehicle and the front vehicle is set, Vh is the current actual speed of the host vehicle, Vt is the expected speed of the host vehicle, and Dr is the relative distance between the host vehicle and the front vehicle;
the determined initial value of the braking deceleration is smoothed, and the target braking deceleration of the vehicle at the current time is determined.
2. The method of claim 1, wherein the step of determining the current driving mode of the host vehicle comprises:
judging whether a front vehicle with a longitudinal distance from the vehicle within a preset distance range exists in front of a lane where the vehicle runs;
if not, determining that the current running mode of the vehicle is a cruise mode;
if yes, judging whether the current actual speed of the front vehicle is greater than the current actual speed of the vehicle;
if so, determining that the current running mode of the vehicle is a cruise mode; otherwise, the current driving mode of the vehicle is determined to be the following mode.
3. The method according to claim 1, wherein the relevant driving parameters of the host vehicle include a current actual vehicle speed and a desired vehicle speed of the host vehicle when the current driving mode of the host vehicle is the cruise mode, and the step of determining the target braking deceleration of the host vehicle at the current time according to the relevant driving parameters of the host vehicle comprises:
according to the current actual speed and the expected speed of the vehicle, the target braking deceleration At corresponding to the current actual speed and the expected speed is found out from a preset comparison relation table1。
4. The method of claim 1, wherein the step of smoothing the determined initial value of braking deceleration and determining the target braking deceleration of the host vehicle at the current time comprises:
comparing the initial brake deceleration value At _ raw with a preset brake deceleration upper limit value Gain1, and outputting a first parameter value At _ upper with a larger value;
comparing the output first parameter value At _ upper with the brake deceleration output value At _ delay output by the host vehicle At the previous moment, and judging whether the brake deceleration output value At _ delay is greater than or equal to the first parameter value At _ upper;
if the current braking deceleration is larger than or equal to the target braking deceleration, outputting the first parameter value At _ upper as the target braking deceleration of the vehicle At the current moment;
comparing the initial brake deceleration value At _ raw with a preset lower brake deceleration limit value Gain2, and outputting a second parameter value At _ lower with a smaller value;
if the brake deceleration output value At _ delay is smaller than the first parameter value At _ upper, outputting the brake deceleration output value At _ delay output by the host vehicle At the previous moment, and judging whether the brake deceleration output value At _ delay is smaller than the second parameter value At _ lower;
if the current braking deceleration is smaller than the target deceleration, outputting the second parameter value At _ lower as the target braking deceleration of the vehicle At the current moment; on the contrary, the brake deceleration output value At _ delay output by the host vehicle At the previous time is output as the target brake deceleration of the host vehicle At the current time.
5. The method of claim 1, wherein when the current driving mode of the host vehicle is a follow-up mode, the method further comprises:
calculating the collision duration required by the collision between the vehicle and the front vehicle according to the relative distance between the vehicle and the front vehicle and the relative speed between the vehicle and the front vehicle;
and determining the braking deceleration change slope of the braking deceleration of the vehicle in each unit collision time length from a preset comparison relation table according to the calculated collision time length, and controlling the vehicle to adjust the actual braking deceleration of the vehicle according to the determined braking deceleration change slope until the target braking deceleration is adjusted.
6. A vehicle braking deceleration determination apparatus, characterized by comprising:
the first determination module is used for determining the current running mode of the vehicle when the vehicle is in an automatic driving state;
the second determining module is used for determining the target braking deceleration of the vehicle at the current moment according to the relevant running parameters of the vehicle when the current running mode of the vehicle is the cruise mode;
the third determining module is used for determining the target braking deceleration of the vehicle at the current moment according to the related running parameters of the vehicle and the front vehicle when the current running mode of the vehicle is the following mode; the front vehicle is a vehicle which is positioned in front of a lane where the vehicle runs and the longitudinal distance between the front vehicle and the vehicle is within a preset distance range;
when the current running mode of the vehicle is a following mode, the third determination module includes:
the fourth determining unit is used for determining the current running state of the vehicle according to the relevant running parameters of the vehicle and the relevant running parameters of the front vehicle;
a fifth determining unit, configured to determine initial values of braking deceleration of the vehicle in different driving states according to the related driving parameters of the vehicle and the preceding vehicle;
a sixth determining unit, configured to perform smoothing processing on the determined initial value of the braking deceleration, and determine a target braking deceleration of the host vehicle at the current time;
the fifth determination unit includes:
the first determining subunit is configured to, if the current driving state of the host vehicle is a transition control state, pass through a formula according to an expected vehicle speed of the host vehicle, an expected following distance of the host vehicle, a current actual vehicle speed of the host vehicle, and a relative distance between the host vehicle and a preceding vehicle:
Figure FDA0002545657930000031
determining the initial value At of braking deceleration of the vehicle in the transient control state2Wherein, Vt is the expected speed of the vehicle, Vh is the current actual speed of the vehicle, Dr is the relative distance between the vehicle and the front vehicle, and Dt is the expected following distance of the vehicle;
a second determining subunit, configured to, if the current driving state of the host vehicle is a normal following state, pass through a formula according to an expected vehicle speed of the host vehicle, a minimum safe distance between the host vehicle and a preceding vehicle, a current actual vehicle speed of the host vehicle, and a relative distance between the host vehicle and the preceding vehicle:
Figure FDA0002545657930000041
determining the initial value At of braking deceleration of the vehicle under the normal following state3Wherein D isMinsafeThe minimum safe distance between the host vehicle and the front vehicle is set on the host vehicle, Vh is the current actual speed of the host vehicle, Vt is the expected speed of the host vehicle, and Dr is the relative distance between the host vehicle and the front vehicle.
7. An automobile characterized by comprising the vehicle braking deceleration determination apparatus according to claim 6.
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