CN113653796A - Vehicle AMT gear shifting method based on road parameters - Google Patents
Vehicle AMT gear shifting method based on road parameters Download PDFInfo
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16H—GEARING
- F16H59/00—Control inputs to control units of change-speed-, or reversing-gearings for conveying rotary motion
- F16H59/60—Inputs being a function of ambient conditions
- F16H59/66—Road conditions, e.g. slope, slippery
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16H—GEARING
- F16H59/00—Control inputs to control units of change-speed-, or reversing-gearings for conveying rotary motion
- F16H59/36—Inputs being a function of speed
- F16H59/44—Inputs being a function of speed dependent on machine speed of the machine, e.g. the vehicle
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16H—GEARING
- F16H59/00—Control inputs to control units of change-speed-, or reversing-gearings for conveying rotary motion
- F16H59/50—Inputs being a function of the status of the machine, e.g. position of doors or safety belts
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16H—GEARING
- F16H59/00—Control inputs to control units of change-speed-, or reversing-gearings for conveying rotary motion
- F16H59/50—Inputs being a function of the status of the machine, e.g. position of doors or safety belts
- F16H59/52—Inputs being a function of the status of the machine, e.g. position of doors or safety belts dependent on the weight of the machine, e.g. change in weight resulting from passengers boarding a bus
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16H—GEARING
- F16H59/00—Control inputs to control units of change-speed-, or reversing-gearings for conveying rotary motion
- F16H59/60—Inputs being a function of ambient conditions
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16H—GEARING
- F16H61/00—Control functions within control units of change-speed- or reversing-gearings for conveying rotary motion ; Control of exclusively fluid gearing, friction gearing, gearings with endless flexible members or other particular types of gearing
- F16H61/02—Control functions within control units of change-speed- or reversing-gearings for conveying rotary motion ; Control of exclusively fluid gearing, friction gearing, gearings with endless flexible members or other particular types of gearing characterised by the signals used
- F16H61/0202—Control functions within control units of change-speed- or reversing-gearings for conveying rotary motion ; Control of exclusively fluid gearing, friction gearing, gearings with endless flexible members or other particular types of gearing characterised by the signals used the signals being electric
- F16H61/0204—Control functions within control units of change-speed- or reversing-gearings for conveying rotary motion ; Control of exclusively fluid gearing, friction gearing, gearings with endless flexible members or other particular types of gearing characterised by the signals used the signals being electric for gearshift control, e.g. control functions for performing shifting or generation of shift signal
- F16H61/0213—Control functions within control units of change-speed- or reversing-gearings for conveying rotary motion ; Control of exclusively fluid gearing, friction gearing, gearings with endless flexible members or other particular types of gearing characterised by the signals used the signals being electric for gearshift control, e.g. control functions for performing shifting or generation of shift signal characterised by the method for generating shift signals
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- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16H—GEARING
- F16H61/00—Control functions within control units of change-speed- or reversing-gearings for conveying rotary motion ; Control of exclusively fluid gearing, friction gearing, gearings with endless flexible members or other particular types of gearing
- F16H61/18—Preventing unintentional or unsafe shift, e.g. preventing manual shift from highest gear to reverse gear
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16H—GEARING
- F16H63/00—Control outputs from the control unit to change-speed- or reversing-gearings for conveying rotary motion or to other devices than the final output mechanism
- F16H63/40—Control outputs from the control unit to change-speed- or reversing-gearings for conveying rotary motion or to other devices than the final output mechanism comprising signals other than signals for actuating the final output mechanisms
- F16H63/42—Ratio indicator devices
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16H—GEARING
- F16H59/00—Control inputs to control units of change-speed-, or reversing-gearings for conveying rotary motion
- F16H59/60—Inputs being a function of ambient conditions
- F16H59/66—Road conditions, e.g. slope, slippery
- F16H2059/663—Road slope
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16H—GEARING
- F16H59/00—Control inputs to control units of change-speed-, or reversing-gearings for conveying rotary motion
- F16H59/60—Inputs being a function of ambient conditions
- F16H59/66—Road conditions, e.g. slope, slippery
- F16H2059/666—Determining road conditions by using vehicle location or position, e.g. from global navigation systems [GPS]
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Abstract
The invention discloses a vehicle AMT gear shifting method based on road parameters, which comprises the steps of dividing a target road interval into N road sections, and inputting road characteristic parameters and vehicle performance parameters corresponding to the road sections into a memory storage unit of a vehicle; when the vehicle runs in the target road interval, judging that the current road section of the vehicle is an X road section and the road section to which the vehicle is about to run is an X +1 road section, calculating a first constraint vehicle speed of the X road section based on the road characteristic parameter and the vehicle performance parameter of the X road section, calculating a second constraint vehicle speed of the X +1 road section based on the road characteristic parameter and the vehicle performance parameter of the X +1 road section, and taking the smaller value of the first constraint vehicle speed and the second constraint vehicle speed as the control vehicle speed of the X road section and the X +1 road section; and acquiring a new gear shifting schedule diagram based on the control vehicle speed, and executing gear shifting according to the new gear shifting schedule diagram on the Xth road section and the X +1 th road section by the vehicle. The invention can realize accurate gear switching, and improves the service life of related parts and the safety of vehicles.
Description
Technical Field
The invention discloses a vehicle AMT gear shifting method, belongs to the technical field of vehicle gear shifting methods, and particularly discloses a vehicle AMT gear shifting method based on road parameters.
Background
With the high-speed development of highway construction in China and the change of travel demands of people, vehicles play an important role in realizing high-efficiency and rapid transportation. The method has the advantages that the driving characteristics of the vehicle in a specific road section are known, the vehicle gear shifting strategy is researched, the fuel economy of the vehicle is improved, and the method is important for vehicle engineering research.
The two-parameter gear shifting strategy which is most commonly used at present takes the vehicle speed and the throttle opening as the most main gear shifting control parameters to determine the gear shifting time and the gear shifting operation process, and a gear shifting rule is made according to the optimal dynamic property or the optimal economic property under the steady-state working condition. The gear shifting strategy is formulated under the steady-state driving condition of a straight road vehicle, the road environment of the vehicle in actual driving is not taken into consideration, only the state parameters of the vehicle in the driving process are taken as the formulation factors of the gear shifting strategy, the actual driving environment of the vehicle is complex and changeable, the requirements of drivers with different driving habits on the gear shifting rule are greatly different, and the driving safety of the vehicle is difficult to effectively ensure by adopting a basic gear shifting mode when the road environment changes.
Disclosure of Invention
Aiming at the technical problems in the prior art, the invention provides a vehicle AMT gear shifting method based on road parameters, which overcomes the defect that the driving safety of an automobile cannot be ensured due to the specific road line shape in the prior art, can realize accurate gear shifting, and improves the service life of related parts and the safety of the automobile.
The invention discloses a vehicle AMT gear shifting method based on road parameters, which comprises the steps of dividing a target road interval into N road sections, obtaining road characteristic parameters of each road section, obtaining vehicle performance parameters of vehicles running in the target road interval, and inputting the road characteristic parameters and the vehicle performance parameters corresponding to each road section into a memory storage unit of the vehicle; when a vehicle runs in a target road interval, judging that the current road section of the vehicle is an Xth road section, the road section to which the vehicle is about to run is an Xth +1 road section, wherein X +1 is less than or equal to N, acquiring road characteristic parameters and vehicle performance parameters corresponding to the Xth road section based on a memory storage unit, calculating a first constraint vehicle speed of the Xth road section based on the road characteristic parameters and the vehicle performance parameters of the Xth road section, acquiring road characteristic parameters and vehicle performance parameters corresponding to the Xth +1 road section, calculating a second constraint vehicle speed of the Xth +1 road section based on the road characteristic parameters and the vehicle performance parameters of the Xth +1 road section, and taking the smaller value of the first constraint vehicle speed and the second constraint vehicle speed as the control vehicle speeds of the Xth road section and the Xth +1 road section; and acquiring a new gear shifting schedule diagram based on the control vehicle speed, and executing gear shifting on the vehicle on the X road section and the X +1 road section according to the new gear shifting schedule diagram, wherein X, N are natural numbers.
In a preferred embodiment of the present invention, the road characteristic parameters include a post number, a road alignment parameter, a road speed limit, a rolling resistance coefficient, and a road surface friction coefficient, and the road alignment parameter includes a longitude and latitude, a road curve radius, a longitudinal gradient, and a transverse gradient; the vehicle performance parameters comprise the full-load mass of the vehicle, the radius of wheels, the wheel track of the vehicle, the transmission ratio of different gears, the transmission ratio of a main speed reducer, an air resistance coefficient, the windward area, the mechanical efficiency of an automobile transmission system and the height of the mass center of the automobile.
In a preferred embodiment of the invention, each road segment is determined to be a straight or curved line segment based on the road curve radius R and the longitudinal slope α of the road alignment parameter.
In a preferred embodiment of the present invention, when the vehicle travels in the target road section, the position information of the vehicle is collected in real time, and it is determined whether the vehicle is in a normal travel state:
step one, obtaining the current vehicle speed of the vehicle in real time according to a vehicle network CAN bus, if the current vehicle speed is lower than a driving threshold value, judging that the vehicle is not in a driving state, stopping retrieving a memory storage unit until the current vehicle speed is greater than the driving threshold value, and entering step two;
step two, acquiring the current position of the vehicle through a GPS in real time, judging whether a road linear parameter corresponding to the current position is stored in a memory storage unit or not, and executing the step one if the road linear parameter corresponding to the current position is not stored in the memory storage unit; if yes, executing the step three;
and step three, acquiring the speed limit value of the current road section, judging whether the current vehicle speed is higher than the speed limit value in real time, if so, giving an alarm to remind a driver of limiting the speed, and otherwise, judging the road section where the current position of the vehicle is located.
In a preferred embodiment of the present invention, the method for determining the road section where the current position of the vehicle is located is as follows:
acquiring the current position of a vehicle through a GPS, and judging the driving direction of the vehicle in a target road section according to the current position information and the current speed information of the vehicle;
and step two, judging that the current position of the vehicle is the Xth road section according to the current position information and the driving direction of the vehicle, and the road section to which the vehicle is about to drive is the X +1 th road section.
In a preferred embodiment of the present invention, in step one,
the method comprises the steps of obtaining longitude and latitude of a starting point and an end point of an X road section through a GPS, determining the driving direction of a vehicle based on the longitude and latitude of the starting point and the end point of the X road section, determining an X +1 road section based on the driving direction of the vehicle, detecting the radius R and the longitudinal gradient alpha of a road curve in real time, and determining the road alignment of the X road section and the X +1 road section.
In a preferred embodiment of the present invention, the acquisition method of the control vehicle speed is as follows:
acquiring road characteristic parameters and vehicle performance parameters of an X road section and an X +1 road section through a memory storage unit; meanwhile, vehicle running state parameters are obtained from a vehicle network CAN bus; the road characteristic parameters, the vehicle performance parameters and the vehicle running state parameters are transmitted to the AMT gear shifting control unit;
secondly, the AMT gear-shifting control unit determines the constraint vehicle speed of the curve road section and the constraint vehicle speed of the straight line section based on the received information;
and step three, taking the smaller value of the two constraint vehicle speeds as the control vehicle speed of the Xth road section and the X +1 th road section.
In a preferred embodiment of the present invention, if the current road segment is a flat curve segment, the constraint vehicle speed is the minimum value of the three of the limit speed of the vehicle rollover, the limit speed of the vehicle sideslip and the road segment speed limit value of the road segment;
if the current road section is a curve uphill section, the constraint vehicle speed is the smaller value of the constraint vehicle speed of the flat curve section and the critical vehicle speed of the curve uphill section;
and if the current road section is a curve downhill section, the constraint vehicle speed is the road section speed limit value of the road section.
In a preferred embodiment of the present invention, if the current road section is a straight road section, the restricted vehicle speed is the road section speed limit value of the road section;
if the current road section is a straight-line uphill section, the constraint vehicle speed is the smaller value of the road section speed limit value of the road section and the critical vehicle speed of the straight-line uphill section;
and if the current road section is a straight line downhill section, the constraint vehicle speed is the road section speed limit value of the road section.
In a preferred embodiment of the present invention, the method of obtaining a new shift schedule map based on a control vehicle speed includes,
judging which gears the controlled vehicle speed is in, when judging that the controlled vehicle speed is in the gear shifting intervals of the N and the N +1 gears, writing the controlled vehicle speed of the current road section unit as the upward gear shifting limit speed into the gear shifting rules of the N and the N +1 gears
The invention has the beneficial effects that: the road parameters are obtained through a road route measuring system based on a GPS, the road alignment of a road to be driven is obtained before the vehicle drives when the vehicle drives on different roads by inputting a speed limit value of a target road section, a road rolling resistance coefficient, and the vehicle mass center height and the wheel track when the vehicle is in no load, the road parameters are submitted to a gear shifting control unit, the running state of an automobile on the front road section is predicted by adopting a gear shifting method of the corresponding road alignment at the initial post number position of the road section, real-time adjustment is carried out to deal with the different road conditions of the vehicle, the gear shifting control unit does not simply depend on the sensor data of the vehicle to estimate the road condition of the current position of the vehicle, and accurate gear shifting is realized under the condition of safety; the automobile has good self-adaptability, improves the driving smoothness, and can ensure the driving safety of the automobile while ensuring the dynamic property and the economical efficiency of the automobile.
Drawings
FIG. 1 is a schematic view of the division of road alignment for an AMT shifting method for a vehicle based on road parameters in accordance with the present invention;
FIG. 2 is a schematic view of various road linear segment combinations of an AMT shifting method for a vehicle based on road parameters according to the present invention;
FIG. 3 is a force diagram of the vehicle during turning according to the AMT shifting method of the vehicle based on road parameters;
FIG. 4 is a shift schedule diagram of a prior art vehicle AMT shift method;
FIG. 5 is a new shift schedule diagram of the vehicle AMT shift method based on road parameters of the present invention.
Detailed Description
The invention will now be described in further detail, including the preferred embodiments, with reference to the accompanying drawings and by way of illustration of some alternative embodiments of the invention. It is to be understood that the described embodiments are merely a few embodiments of the invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments of the present invention without any inventive step, are within the scope of the present invention.
The invention provides a vehicle AMT gear shifting method based on road parameters, which comprises the following steps:
step 1: acquiring road parameters and speed limit values of a target road section to obtain road alignment parameters of the target road section, and dividing the target road section into a plurality of road sections; and storing the road alignment parameters, the road speed limit value, the rolling resistance coefficient and the road surface friction coefficient of each road section, and determining the vehicle performance parameters. The method specifically comprises the following substeps:
step 11: enabling the vehicle to run back and forth once in a target road section in an idle state, and obtaining road alignment parameters of all road sections in the target road section through a road route measuring system based on a GPS (global positioning system), wherein the road alignment parameters comprise longitude and latitude, road curve radius, longitudinal gradient and transverse gradient;
step 12: dividing the road sections in the target road section into straight line sections and curve sections according to the road alignment parameters; according to the curve radius R and the longitudinal gradient alpha of the road, dividing the road section type into a straight line section and a curve section, wherein the straight line section comprises: (1) straight line segment (radius R)>R0Longitudinal gradient alpha1<α<α2) (ii) a (2) Straight line uphill segment (radius R)>R0The longitudinal gradient alpha is more than or equal to alpha2) (ii) a (3) Straight line downhill section (radius R)>R0The longitudinal gradient alpha is less than or equal to alpha1) (ii) a The curve segment includes: (1) flat curve segment (radius R is less than or equal to R)0Longitudinal gradient alpha1<α<α2) (2) an upward slope section of the curve (radius R is less than or equal to R)0The longitudinal gradient alpha is more than or equal to alpha2) (3) a curve descending section (radius R is less than or equal to R)0The longitudinal gradient alpha is less than or equal to alpha1). Wherein R is0、α1、α2Adjusted for different road types, the division criteria of which are shown in fig. 1, in one non-limiting example R0Is 850 m; alpha is alpha1Is-3%, alpha23.5%, where a negative value of the ramp represents a downhill slope and a positive value of the ramp represents an uphill slope. Such as alpha1A value of-3% indicates a downhill slope of 3%, α2A value of 3.5% indicates an uphill slope with a slope of 3.5%. E.g. a certain road radiusR is 500m and the gradient is-5%, according to the standard of fig. 2, the type of the road section is a curve downhill section; the start point of each road segment is marked with a stake number as shown in fig. 3.
Step 13: inputting road linear parameters and pile numbers of each road section into a memory storage unit (hereinafter referred to as AUM); and inputting the speed limit value, the rolling resistance coefficient and the road surface friction coefficient of each road section in the target road section (the rolling resistance coefficient and the road surface friction coefficient are selected according to the road surface conditions, such as tables 1 and 2). Vehicle performance parameters (vehicle full load mass, wheel radius, vehicle wheel track, transmission ratio of different gears, main reducer transmission ratio, air resistance coefficient, windward area, mechanical efficiency of an automobile transmission system, automobile mass center height, which can be obtained by an automobile manufacturer) are input.
Step 2: and (3) in the process that the vehicle runs in the target road section, acquiring the position information of the vehicle in real time, judging whether the vehicle is in a normal running state or not, and if so, entering the step 3. The method specifically comprises the following substeps:
step 21: obtaining the current speed of the vehicle in real time according to the CAN bus of the vehicle-mounted network, if the current speed is lower than a running threshold (in a non-limiting example, the running threshold is set to be 5km/h), judging that the vehicle is not in a running state, stopping searching AUM until the current speed is greater than the running threshold, and entering step 22;
step 22: acquiring the current position of the vehicle through a GPS in real time, judging whether a road alignment parameter corresponding to the current position is stored in the AUM, and if not, executing the step 1; if yes, executing step 23;
step 23: obtaining a speed limit value of a current road section, judging whether the current vehicle speed is higher than the speed limit value in real time, and if so, giving an alarm to remind a driver of limiting the speed; otherwise, executing step 3.
And step 3: the method comprises the following steps of acquiring the current position of a vehicle through a GPS, and judging the driving direction of the vehicle on a target road according to the position information and the speed information of the vehicle, wherein the specific method comprises the following steps:
step 31: referring to fig. 2, determining a current road segment (for example, a K3-K4 road segment) of the automobile according to the current position of the vehicle, measuring the longitude and latitude of a starting point K3 and a finishing point K4 of the current road segment through a GPS, and calculating the distances s3 and s4 between the current position of the vehicle and the starting point K3 and the finishing point K4 of the current road segment; calculating the distances s3 'and s 4' of the current position distances K3 and K4 of the vehicle at the next moment after 1 second; if s3> s3 ', the traveling direction of the vehicle is considered to be the direction K3-K4, and if s3< s 3', the traveling direction of the vehicle is considered to be the direction K4-K3;
step 32: the specific method for judging the road line shapes of the current road section and the road section in front of the vehicle according to the driving direction of the vehicle comprises the following steps:
detecting the radius R and the longitudinal gradient alpha of a road curve in real time, and determining the road alignment of the current road section;
then, the road alignment of the road section ahead of the vehicle is determined according to the traveling direction of the vehicle.
For example, when the automobile runs in the K3-K4 segment and the driving direction is K3-K4, the road curve radius R of the K3-K4 segment is 500m and the slope α is 5%, which satisfy the standard of the curve uphill segment in fig. 1; if the automobile runs in the K3-K4 segments and the driving direction is K4-K3, the curve downhill section criterion is satisfied when the road curve radius R of the K4-K3 segments is 500m and the slope α is-5% due to the change of the slope direction.
Step 33: obtaining road alignment parameters and vehicle performance parameters of a current road section and a front road section through AUM (parameters stored in step 1); meanwhile, vehicle running state parameters (including vehicle speed, engine speed, throttle opening and transmission gear) are obtained from a vehicle-mounted network CAN bus; transmitting the road alignment parameter, the vehicle performance parameter and the vehicle running state parameter to an AMT gear shifting control unit;
and 4, step 4: the AMT gear-shifting control unit processes the received information in real time, takes the current road section and the front road section as a road section unit for consideration, and determines the constraint speed of the vehicle in the current road section unit; the method specifically comprises the following steps:
step 41: determining the constrained vehicle speed of a curve section (comprising a flat curve section, a curve ascending section and a curve descending section); the method comprises the following specific steps:
(1) if the current curve section is a flat curve section, determining the restrained speed of the automobile on the curve, specifically as follows:
the limiting speed of the automobile rollover on the curve road section is vrReferring to FIG. 3, the equation (1) should be satisfied when the vehicle does not roll over
From the equation (1), the limiting speed of the vehicle at which the vehicle rolls over is:
the limiting speed of the automobile sideslip on the curve section is vsReferring to FIG. 3, the equation (3) is satisfied when the automobile does not sideslip
From equation (3), the limiting speed of the vehicle at which side-slip occurs is:
in formulas (1) to (4): m is the full load mass of the vehicle, kg; v is vehicle speed, m/s; beta is the transverse gradient, °; r is the radius of a road curve, m; h is the height of the center of gravity, m; b is the vehicle track, m; μ is a friction coefficient of the road surface, and is obtained from table 1 according to the road surface condition.
The speed limit value v of the road section is retrieved from the AUMlAnd obtaining the constrained vehicle speed vm1 of the automobile on the curve by using the formula 5:
vm1＝min{vr，vs，vl} (5)；
(2) if the current curve section is the curve uphill section, calculating the constraint vehicle speed of the vehicle on the curve uphill section, which is concretely as follows:
assuming that the automobile is in a constant speed state in the climbing transient state, the mechanical equilibrium equation is as follows:
Fi＝Ft-(Ff+Fw) (6)
in the formula, FtAs a driving force of the vehicle, FfTo rolling resistance, FwAs air resistance, FiIs the slope resistance.
Engine torque TtqViewed as a function of engine speed n, the polynomial can be expressed as:
Ttq＝a0+a1n+a2n2+L+a5n5 (9)
in the formula: ttqIs the engine torque; n.m; n is the engine speed, r/min; coefficient a0，a1，a2，...，a5Can be obtained by least squares fitting from experimental data.
Using equation 10, the critical vehicle speed v that can pass through the uphill section is calculateda：
In the formulas (7) to (10), m is the vehicle full load mass, kg; t istqIs the engine torque, N · m; i.e. igThe gear ratio of the gear of the automobile; i.e. imThe transmission ratio of the main speed reducer is set; etatMechanical efficiency of the vehicle driveline; r is the wheel radius, m; f is a rolling resistance coefficient selected from table 2 according to the road surface condition; α is the longitudinal gradient, °; CD is the air resistance coefficient; a is the windward area, m2(ii) a v is vehicle speed, m/s; and n is the engine speed r/min.
By using maleFormula 11, obtaining the constrained speed v of the automobile on the uphill road section of the curvem2：
vm2＝min{vm1，vα} (11)；
(3) If the curve section is a curve downhill section, the section speed limit value v is retrieved from the AUMlV is to bem3＝vlAs the restrained speed of the automobile on the curve downhill section.
Step 42: determining the constrained vehicle speed of a straight line section (comprising a straight section, a straight ascending section and a straight descending section); the method comprises the following specific steps:
(1) if the straight line section is a straight section, retrieving the speed limit value v of the current section from the AUMl，vm4＝vlAs a constraint speed of the automobile on a straight road section.
(2) If the straight line section is a straight uphill section, a critical vehicle speed v that can pass through the uphill section is first calculated using equation 10αThen, the speed limit value v of the road section is retrieved in the AUMlObtaining the constrained vehicle speed v of the straight-line uphill section by using the formula 12m5：
vm5＝min{vl，vα} (12)；
(3) If the straight line section is a straight downhill section, the section speed limit value v is retrieved from the AUMlV is to bem6＝vlAs the restraint speed of the automobile in the straight line downhill section.
Step 43: and through the steps 41 and 42, obtaining the constrained vehicle speeds of the current road section and the front road section respectively, then taking the current road section and the front road section as a road section unit, and taking the smaller value of the constrained vehicle speeds as the control vehicle speed of the current road section unit.
And 5: the design idea of the method is to add an upward gear shifting limit on the conventional gear shifting rule so as to ensure the safety and dynamic property of the current road section and the front road section of the vehicle.
FIG. 4 is a shift schedule diagram for N and N +1 gears, including downshift line A-B-C-D (N +1 downshifting N) and upshift line X-Y-Z-O (N upshifting N + 1), for which shifts are not required for operation in the space defined by downshift line A-B-C-D (N +1 downshifting N) and upshift line X-Y-Z-O (N upshifting N + 1), for which shifts are required to be shifted to the next lower gear for operation on downshift line A-B-C-D (N +1 downshifting N) or in the region to the left thereof, and for which shifts are required to be shifted to the next higher gear for operation on upshift line X-Y-Z-O (N upshifting N + 1) or in the region to the right thereof,
respectively calculating the constrained speeds of the current road section and the front road section by using the steps 41 and 42 according to the road types and the road line shapes of the current road section and the front road section, taking the minimum value of the two as the control speed of the current road section unit, judging which gear positions the control speed is in, if the control speed is judged to be in the gear shifting interval of the N and the N +1 gears, writing the control speed of the current road section unit as an upward shift limit speed into the gear shifting rule of the N and the N +1 gears, such as an E-F-G line in figure 5, wherein an F point is an intersection point of an upward shift line X-Y-Z-O and an upward shift limit speed E-F-G line, the maximum speed of the vehicle at the gear positions (the N and the N +1 gears) shown in the figure is greater than the control speed of the current road section unit, and writing the control speed of the current road section unit as the upward shift limit speed into the gear shifting strategy, if the opening of the throttle valve of the automobile and the automobile speed are on the upward gear shifting line X-Y-F or the right area of the upward gear shifting line X-Y-F, no gear shifting measures are taken, and the speed of the automobile is reduced to be increased too fast due to the small transmission ratio of a high gear position and exceeds the control speed; if the vehicle speed exceeds the control vehicle speed, a meter needs to display that 'you exceed the safe vehicle speed and please slow down' or an audio is played in the vehicle that 'you exceed the safe vehicle speed and please slow down'. I.e., the upshift profile line is changed to E-F-Z-O, as shown in fig. 5. If the maximum speed (not marked in the gear diagram) of the automobile at a certain gear is less than the control speed of the current road section unit, shifting according to the original economic gear shifting rule or performance gear shifting rule to shift gears.
The required parameters in the above formula are obtained as follows:
the vehicle speed v, the longitudinal acceleration a, the engine speed n and the transmission gear are all obtained from a vehicle network CAN bus in the vehicle running process; road speed limit value vlThe longitudinal slope angle alpha, the transverse slope angle beta and the road curve radius R are obtained from AUM;vehicle full load mass m, wheel radius r, vehicle wheel track B and transmission ratio i of different gearsgMain reducer transmission ratio imAir resistance coefficient CDFrontal area A, mechanical efficiency eta of automobile transmission systemtAnd the height h of the mass center of the automobile is obtained according to the automobile manufacturer. The friction coefficient and the rolling resistance coefficient of the road surface are stored in the AUM, respectively shown in the table 1 and the table 2, and are called from a memory storage unit AUM of the vehicle when the vehicle needs to be used.
In the invention, the influence of the road alignment on the driving safety is considered, the control speed of the current road section unit is introduced, and in the gear shifting strategy of the AMT, which gear intervals the control speed is in is judged and used as the limit speed of gear shifting upwards, namely, the vehicle does not shift upwards after exceeding the control speed, so that the driving safety of the vehicle is improved.
Although exemplary embodiments incorporating the principles of the present invention have been disclosed above, the present invention is not limited to the disclosed embodiments. This application is intended to cover any variations, uses, or adaptations of the invention using its general principles. Further, this application is intended to cover such departures from the present disclosure as come within known or customary practice in the art to which this invention pertains and which fall within the limits of the appended claims.
| Road surface | Coefficient of friction |
| Asphalt or concrete (dry) | 0.8-0.9 |
| Asphalt (Wet) | 0.5-0.7 |
| Concrete (Wet) | 0.8 |
| Gravel | 0.6 |
| Dirt road (Dry) | 0.68 |
| Dirt road (Wet) | 0.55 |
| Snow (pressing) | 0.2 |
| Ice | 0.1 |
TABLE 1 values of the coefficients of friction of the road surfaces
TABLE 2 values of the coefficient of rolling resistance f
It should be understood that the above-mentioned embodiments are merely exemplary of the present invention, and not restrictive, and that any modifications, combinations, substitutions, improvements, etc. made within the spirit and scope of the present invention are included in the present invention.
Claims (10)
1. A vehicle AMT gear shifting method based on road parameters is characterized in that: dividing a target road section into N road sections, acquiring road characteristic parameters of each road section, acquiring vehicle performance parameters of vehicles running in the target road section, and inputting the road characteristic parameters and the vehicle performance parameters corresponding to the road sections into a memory storage unit of the vehicle; when a vehicle runs in a target road interval, judging that the current road section of the vehicle is an Xth road section, the road section to which the vehicle is about to run is an Xth +1 road section, wherein X +1 is less than or equal to N, acquiring road characteristic parameters and vehicle performance parameters corresponding to the Xth road section based on a memory storage unit, calculating a first constraint vehicle speed of the Xth road section based on the road characteristic parameters and the vehicle performance parameters of the Xth road section, acquiring road characteristic parameters and vehicle performance parameters corresponding to the Xth +1 road section, calculating a second constraint vehicle speed of the Xth +1 road section based on the road characteristic parameters and the vehicle performance parameters of the Xth +1 road section, and taking the smaller value of the first constraint vehicle speed and the second constraint vehicle speed as the control vehicle speeds of the Xth road section and the Xth +1 road section; and acquiring a new gear shifting schedule diagram based on the control vehicle speed, and executing gear shifting according to the new gear shifting schedule diagram on the Xth road section and the X +1 th road section by the vehicle.
2. The road parameter based vehicle AMT gear shifting method according to claim 1, wherein: the road characteristic parameters comprise pile numbers, road alignment parameters, road speed limit values, rolling resistance coefficients and road surface friction coefficients, and the road alignment parameters comprise longitude and latitude, road curve radius, longitudinal gradient and transverse gradient; the vehicle performance parameters comprise the full-load mass of the vehicle, the radius of wheels, the wheel track of the vehicle, the transmission ratio of different gears, the transmission ratio of a main speed reducer, an air resistance coefficient, the windward area, the mechanical efficiency of an automobile transmission system and the height of the mass center of the automobile.
3. The road parameter based vehicle AMT gear shifting method according to claim 1, wherein: and determining each road section as a straight line section or a curve section based on the road curve radius R and the longitudinal gradient alpha of the road alignment parameter.
4. The road parameter based vehicle AMT gear shifting method according to claim 1, wherein: when the vehicle runs in the target road interval, the position information of the vehicle is collected in real time, and whether the vehicle is in a normal running state is judged:
step one, obtaining the current vehicle speed of the vehicle in real time according to a vehicle network CAN bus, if the current vehicle speed is lower than a driving threshold value, judging that the vehicle is not in a driving state, stopping retrieving a memory storage unit until the current vehicle speed is greater than the driving threshold value, and entering step two;
step two, acquiring the current position of the vehicle through a GPS in real time, judging whether a road linear parameter corresponding to the current position is stored in a memory storage unit or not, and executing the step one if the road linear parameter corresponding to the current position is not stored in the memory storage unit; if yes, executing the step three;
and step three, acquiring the speed limit value of the current road section, judging whether the current vehicle speed is higher than the speed limit value in real time, if so, giving an alarm to remind a driver of limiting the speed, and otherwise, judging the road section where the current position of the vehicle is located.
5. The road parameter based vehicle AMT gear shifting method according to claim 1, wherein: the method for judging the road section where the current position of the vehicle is located comprises the following steps:
acquiring the current position of a vehicle through a GPS, and judging the driving direction of the vehicle in a target road section according to the current position information and the current speed information of the vehicle;
and step two, judging that the current position of the vehicle is the Xth road section according to the current position information and the driving direction of the vehicle, and the road section to which the vehicle is about to drive is the X +1 th road section.
6. The road parameter based vehicle AMT shifting method according to claim 5, characterized in that: in the first step of the method,
the method comprises the steps of obtaining longitude and latitude of a starting point and an end point of an X road section through a GPS, determining the driving direction of a vehicle based on the longitude and latitude of the starting point and the end point of the X road section, determining an X +1 road section based on the driving direction of the vehicle, detecting the radius R and the longitudinal gradient alpha of a road curve in real time, and determining the road alignment of the X road section and the X +1 road section.
7. The road parameter based vehicle AMT gear shifting method according to claim 1, wherein: the method for acquiring the control vehicle speed comprises the following steps:
acquiring road characteristic parameters and vehicle performance parameters of an X road section and an X +1 road section through a memory storage unit; meanwhile, vehicle running state parameters are obtained from a vehicle network CAN bus; the road characteristic parameters, the vehicle performance parameters and the vehicle running state parameters are transmitted to the AMT gear shifting control unit;
secondly, the AMT gear-shifting control unit determines the constraint vehicle speed of the curve road section and the constraint vehicle speed of the straight line section based on the received information;
and step three, taking the smaller value of the two constraint vehicle speeds as the control vehicle speed of the Xth road section and the X +1 th road section.
8. The road parameter based vehicle AMT shift method according to claim 7, wherein:
if the current road section is a flat curve section, the constraint vehicle speed is the minimum value of the three of the limit speed of the vehicle rollover, the limit speed of the vehicle sideslip and the road section speed limit value of the road section;
if the current road section is a curve uphill section, the constraint vehicle speed is the smaller value of the constraint vehicle speed of the flat curve section and the critical vehicle speed of the curve uphill section;
and if the current road section is a curve downhill section, the constraint vehicle speed is the road section speed limit value of the road section.
9. The road parameter based vehicle AMT shift method according to claim 7, wherein:
if the current road section is a straight road section, the constraint vehicle speed is the road section speed limit value of the road section;
if the current road section is a straight-line uphill section, the constraint vehicle speed is the smaller value of the road section speed limit value of the road section and the critical vehicle speed of the straight-line uphill section;
and if the current road section is a straight line downhill section, the constraint vehicle speed is the road section speed limit value of the road section.
10. The road parameter based vehicle AMT gear shifting method according to claim 1, wherein: the method of obtaining a new shift schedule based on controlling vehicle speed includes,
and judging a gear shifting interval where the control vehicle speed is positioned, and when the control vehicle speed is judged to be in the gear shifting intervals of the N and the N +1 gears, writing the control vehicle speed of the current road section unit as an upward gear shifting limit speed into the gear shifting rules of the N and the N +1 gears.
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