CN110154784B - Driver demand driving torque online determination method - Google Patents

Driver demand driving torque online determination method Download PDF

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CN110154784B
CN110154784B CN201910479128.3A CN201910479128A CN110154784B CN 110154784 B CN110154784 B CN 110154784B CN 201910479128 A CN201910479128 A CN 201910479128A CN 110154784 B CN110154784 B CN 110154784B
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driving force
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accelerator pedal
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CN110154784A (en
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管欣
金号
段春光
卢萍萍
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Jilin University
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Jilin University
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60L—PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES; SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL; MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
    • B60L15/00—Methods, circuits, or devices for controlling the traction-motor speed of electrically-propelled vehicles
    • B60L15/20—Methods, circuits, or devices for controlling the traction-motor speed of electrically-propelled vehicles for control of the vehicle or its driving motor to achieve a desired performance, e.g. speed, torque, programmed variation of speed
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60L—PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES; SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL; MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
    • B60L2250/00—Driver interactions
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00—Road transport of goods or passengers
    • Y02T10/60—Other road transportation technologies with climate change mitigation effect
    • Y02T10/72—Electric energy management in electromobility

Abstract

The invention relates to an on-line determination method for driver required driving torque, and belongs to the technical field of vehicle required driving torque calibration. The method comprises the steps of determining a running resistance curve and a maximum driving force curve, determining a required driving force request curve and the maximum speed of a vehicle at the wheel end when an accelerator pedal is 100%, designing an insensitive area and a sensitive area of the accelerator pedal, determining a complete driver required driving force map matrix table at the wheel end on line, and calculating the required driving torque of a driver to the output end of an engine. The driver required driving torque online determination method is simple to use, does not need to calibrate an offline driver required driving torque map table, and reduces the development time and cost of the whole vehicle. The acceleration/deceleration of the automobile under various driving environments and the easy control performance of the speed of the automobile are ensured by planning the sensitive area and the insensitive area of the pedal on line, and the driving quality of the automobile is effectively improved.

Description

Driver demand driving torque online determination method
Technical Field
The invention belongs to the technical field of vehicle required driving torque calibration, and particularly relates to an online determination method for driver required driving torque.
Background
With the rapid development of automobiles, consumers are more and more concerned about the driving feeling (driving quality) of automobiles. The traditional accelerator pedal and a throttle valve are directly and mechanically connected, so that the driving feeling cannot be configured in a personalized way and the requirement of a consumer is difficult to meet, therefore, the automobile at the present stage adopts the electronic throttle valve, the driving feeling expected by the driver is met by configuring the mapping relation between the accelerator pedal and the required driving torque, if the mapping relation is not configured reasonably, the negative phenomena of too sensitive response, too slow response, large gear shifting impact and the like of the vehicle to the input of the accelerator pedal easily occur, the state of the vehicle is difficult to control by the driver, and the bad driving experience is brought to the driver. As described above, how to determine the map of the accelerator pedal and the required drive torque becomes one of the key issues in determining the driving quality of the vehicle, and therefore, it is very important to study how to determine the required drive torque of the driver from the accelerator pedal.
From published documents, documents on how to determine a mapping relation between an accelerator pedal and a required driving torque are few in the prior art, and patents such as chinese patent "a calculation method for driver required torque of a planetary series-parallel hybrid vehicle" 201710116079.8, "a method for estimating driver required torque of a CVT parallel hybrid vehicle" 201710332175.6, "and" a method for estimating driver required torque of a pure electric vehicle based on information synthesis "201710332177.5 focus on how to determine the required driving torque at 100% of the accelerator pedal according to the current state of the vehicle, and adopt a simple linear mapping relation (T ═ Tmax a) for the magnitude of the required driving torque under other accelerator pedals. Although chinese patent No. 201410222853 refers to a method and system for calculating a torque correction coefficient and analyzing a torque of an electric vehicle, a specific mapping relationship and how to map the torque according to vehicle states such as a vehicle speed, an engine speed, a pedal opening degree, etc., is not explicitly described herein.
Usually, the driving torque required by the driver is obtained by calibrating a driving torque required by the driver map table off line, then pre-storing the driving torque required by the driver in the controller, and then looking up the table according to the current vehicle state. Usually, map tables are calibrated according to specific driving environments, and once the driving environments change, the original map tables are not applicable (for example, the driving feeling of the automobile under the conditions of a horizontal road surface and a slope has obvious difference). Aiming at the problem, the current common solution is to calibrate a plurality of map tables in various driving environments and store the map tables in a controller in advance to ensure the adaptability in various environments, and the mode needs a large amount of calibration work, thereby increasing the development cost of the control algorithm of the whole vehicle.
When a driver drives a car, the driver often difficultly steps on an accelerator pedal under a certain fixed opening degree, the opening degree of the accelerator pedal usually fluctuates, particularly in a low-speed area, the driving torque is greatly changed along with the opening degree of the accelerator pedal, the driver feels that the accelerator pedal is sensitive, the car is difficult to stabilize at an expected speed, and the driving burden and poor driving experience of the driver are undoubtedly increased from the viewpoint of easiness in controlling the speed of the car.
Disclosure of Invention
The invention provides an on-line determination method of a driving torque required by a driver, which aims to solve the problem of poor controllability of a vehicle speed under various complex road environments.
The invention takes an automobile with an engine as a driving power source as a research object, and adopts the technical scheme that the automobile driving power source comprises the following steps:
step 1: determining a driving resistance curve and a maximum driving force curve; the specific implementation of the step is as follows: firstly, the driving resistance characteristic and the maximum driving curve of the vehicle are determined according to the basic parameters related to the driving dynamics of the automobile and the current vehicle state, and the maximum driving curve is determined as follows:
Figure GDA0002423170060000021
in the formula, TtqIs the maximum driving torque curve at the crankshaft end of the engine, igTo the transmission ratio of the variator, i0is the main reducer transmission ratio, is η the mechanical efficiency of the transmission system, and r is the automobile wheel radius;
the method for determining the driving resistance curve on the road surface with the gradient on line is as follows:
Figure GDA0002423170060000022
travel resistance curve on horizontal road surface: f2
Figure GDA0002423170060000023
Wherein G is the total gravity of the automobile, f is the rolling resistance coefficient, CDIs the air resistance coefficient, A is the windward area, u is the vehicle speed, theta is the gradient;
as can be seen from the above two equations, the driving resistance curve is a curve equation which exhibits a parabolic characteristic with speed, and the driving resistance curve on a road with a slope can be approximately regarded as being obtained by translating the driving resistance curve up and down on a horizontal road surface, as follows:
F1(u)＝F2(u)+constant (4)
the driving force F of the wheel end of the whole vehicle can be obtained through calculation by acquiring the output torque and gear information of the engine on the whole vehicle in real timexAnd obtaining the theoretical longitudinal acceleration a which the vehicle should have according to the running resistance curve equation of the horizontal road surfacex_expectLongitudinal acceleration a of the actual vehiclex_real，
Fx-F2(u)＝M*ax_expect(5)
Fx-F1(u)＝M*ax_real(6)
Wherein M is the mass of the vehicle, and simultaneous equations 3, 4, 5, and 6 can yield constant-M (a)x_expect-ax_real) In order to avoid large error when a single point is adopted for estimating the driving resistance curve, values of expected acceleration and actual acceleration of n points are continuously taken within a certain period of time, n constant values are calculated, and the average value is calculated to obtain the final constant value
Figure GDA0002423170060000031
And then determining a running resistance curve when the road gradient exists on line:
Figure GDA0002423170060000032
step 2: determining a driving force curve required by a driver to the wheel end at the time of 100% of an accelerator pedal and a maximum vehicle speed u at the time of 100% of the accelerator pedalmax；
The step 2 is specifically realized as follows: according to the maximum driving force curve of the automobile, when the accelerator pedal is determined to be 100%, the required driving force curve of a driver to the wheel end is obtained by fitting a polynomial through a plurality of points, and the points are selected according to the following scheme:
(1) if the driving force curves of two adjacent gears have an intersection point, the intersection point is taken as one of the points to be subjected to polynomial fitting; if the driving force curves of two adjacent gears do not have an intersection point, a straight line perpendicular to an x axis is made at the position of the corresponding vehicle speed of the engine in the above one gear at the highest rotating speed, and the intersection point of the straight line and the next gear is used as one of points to be subjected to polynomial fitting; when the automobile has n gears, n-1 points can be determined, and a driving force request curve of the wheel end when the accelerator pedal is 100% is obtained by performing n-2 degree polynomial fitting on the n-1 points;
Faccpedal_100％(u)＝a0+a1*u+a2*u2...an-2*un-2(9)
in the formula, Faccpedal_100％(u) is a driving force request curve of the wheel end at 100% accelerator pedal, u is vehicle speed, a0,a1,......an-2Is a polynomial coefficient to be solved;
(2) simultaneously determining the maximum vehicle speed u under the current driving environment by simultaneous formula (1) and formula (2)max；
And step 3: determining a driving force curve required by a driver with 0% of opening of an accelerator pedal for a wheel end and a lowest stable vehicle speed;
the specific implementation of step 3 is as follows: determining the lowest stable vehicle speed of the automobile on a horizontal road surface according to a torque output curve under an idle throttle of the engine, simultaneously determining a driving force curve required by a driver to a wheel end under the condition of 0% pedal opening according to the torque output curve under the idle throttle of the engine, and recording the torque output curve under the idle throttle of the engine as Tengine_min(n), n represents the engine speed r/min,
and converting the torque output curve under the idle throttle of the engine to the wheel end to obtain a driving force curve of the wheel end:
Figure GDA0002423170060000041
according to the following formula:
Figure GDA0002423170060000042
obtaining a torque output curve under an idle throttle of the engine, converting the torque output curve into a change curve of the driving force of a wheel end along with the vehicle speed:
Figure GDA0002423170060000043
in the formula ig1For first gear ratio of the transmission, i0is the main reducer transmission ratio, eta is the mechanical efficiency of the transmission system, r is the automobile wheel radius, and u represents the automobile speed;
(2) the lowest stable speed of the automobile is obtained according to the intersection point of the driving resistance curve and the driving force curve of the automobile on the horizontal road surface, the lowest stable speed is obtained through simultaneous operations (3) and (10) (the intersection point of the driving force and the resistance curve under the idle throttle is the lowest stable speed), and the lowest stable speed is recorded as uminWhile simultaneously adding Fwheel_min(u) as a driver demand drive force curve for the wheel end at 0% pedal opening;
and 4, step 4: designing an accelerator pedal insensitive region; in order to ensure the easiness of the speed control, a pedal insensitive area is designed near the current driving resistance curve of the automobile, and the method is specifically realized as follows:
(1) setting a correspondence between an accelerator pedal opening and a stable vehicle speed
U is determined according to step 2 and step 3min、umaxDesigning m pedal opening degrees:
Figure GDA0002423170060000051
m is a positive integer greater than 2, and the expected stable speed of the automobile is u1/m,u2/m,…u(m-1)/mThe running resistance of the automobile corresponding to the stable speed is F1/m,F2/m...F(m-1)/m；
(2) Setting an upper limit and a lower limit of an insensitive region of an accelerator pedal
Opening degree of an accelerator pedal of
Figure GDA0002423170060000052
When k is an integer of 1 to m, the upper limit value coordinate and the lower limit value coordinate of the insensitive region are (u)k/m,Fk/m+ΔF)，(uk/m,Fk/mΔ F), in a similar manner, from u can be obtained1/mTo u(m-1)/mThe upper limit of the insensitive region of the whole vehicle speed interval is set as (u)1/m，F1/m+ΔF)，(u2/m，F2/m+ΔF),…(u(m-1)/m，F(m-1)/m+ Δ F), the point set of the lower limit of the insensitive region is (u)1/m,F1/m-ΔF)，(u2/m,F2/m-ΔF)，…(u(m-1)/m,F(m-1)/m- Δ F), by adjusting the value of Δ F, an adjustment of the accelerator pedal insensitivity of the pedal insensitive region is achieved;
and 5: designing an accelerator pedal sensitive area; the method comprises the following specific steps:
(1) designing a sensitive area above a driving resistance curve: determining the minimum stable vehicle speed uminThe corresponding running resistance is Ff+w(umin) Determining the maximum driving force F capable of being generated at the wheel end under the lowest stable vehicle speedt_max(umin) Then, the set of key points of the sensitive area above the driving resistance curve is designed as:
Figure GDA0002423170060000053
Figure GDA0002423170060000054
…
Figure GDA0002423170060000055
(2) the sensitive area below the driving resistance curve is designed as follows: the highest vehicle speed umaxSubstituting the formula (8) into the resistance curve formula to obtain the corresponding running resistance Ff+w(umax) Designing a key point set of a sensitive area below a driving resistance curve:
Figure GDA0002423170060000061
Figure GDA0002423170060000062
…
Figure GDA0002423170060000063
step 6: determining a complete driving force map matrix table required by a driver at a wheel end on line; supplementing other spatial points on the basis of the determined key points in the step 4 and the step 5 to form a complete driving force map table required by the driver at the wheel end; the supplement method comprises the following steps: stabilized vehicle speed u according to design1/m,u2/m,…u(m-1)/mNext, the maximum driving force at the current vehicle speed is determined to be Fmax(u1/m)，Fmax(u2/m)...Fmax(u(m-1)/m) Taking the point as a key point of 100% of an accelerator pedal, linearly distributing driving force under other pedal opening degrees and the pedal opening degrees, supplementing point sets above and below an insensitive region of the accelerator pedal according to the method, and finally obtaining all point set distribution of the driving force required by the accelerator pedal;
and 7: calculating driver demand drive torque at an engine output, comprising:
(1) firstly, on the basis of a matrix table of driver required driving force map of the wheel end obtained by online determination in step 6, interpolating according to the current vehicle speed u and the accelerator opening acc _ pedal to obtain the driver required driving force F (u, acc _ pedal) of the wheel end under the current vehicle speed and the accelerator opening;
(2) the method comprises the following steps of calculating the required driving torque of a driver to the output end of an engine according to the required driving force of the driver at the wheel end, and concretely realizing the following steps: converting the driver required driving force of the wheel end under the current vehicle speed and the opening degree of an accelerator pedal to the output end of the engine according to the following formula to obtain the driver required driving torque of the output end of the engine:
Figure GDA0002423170060000064
where ig (n) is the transmission ratio at the current gear, i0 is the final drive ratio, η is the efficiency of the driveline, r is the wheel radius, T is the gear ratio of the transmission at the current gear, anddriverthe driver drives the torque for the demand of the output end of the engine under the current gear, the vehicle speed and the opening degree of an accelerator pedal.
The whole vehicle control system performs torque output control according to the driver required driving torque determined by the method, and mainly has the following characteristics:
the first characteristic is that: the driver required torque is determined on line according to the current driving environment, and the off-line calibration of a driver required driving torque map table is not needed, so that the development time and the development cost of the whole vehicle are greatly reduced.
The second characteristic is that: the driving resistance curve under the current driving environment is determined according to the vehicle state, an accelerator pedal insensitive region is formed near the driving resistance curve, and an accelerator pedal sensitive region is formed far away from the driving resistance curve, so that the speed of the vehicle can be well controlled by a driver, the vehicle speed is easy to control, and the vehicle can be accelerated or decelerated quickly to reach the expected vehicle speed.
The third feature is that: when the driving environment changes (such as gradient, road rolling resistance coefficient and the like), the driving resistance curve of the automobile also changes, and the vehicle speed is ensured to be easy to control only by redesigning a pedal sensitive area and an insensitive area.
The method has the advantages that the required torque of the driver is determined on line according to the current running environment, and the off-line calibration of the required driving torque map table of the driver is not needed, so that the development time and the development cost of the whole vehicle are reduced. An insensitive area of an accelerator pedal is formed near a driving resistance curve, and a sensitive area of the accelerator pedal is formed far away from the driving resistance curve, so that a driver can well control the speed of the automobile, the easiness of controlling the speed of the automobile is realized, and the automobile can be quickly accelerated or decelerated to reach the expected speed. The driving resistance curve is determined on line, sensitive and insensitive areas of an accelerator pedal are planned on line, and the driving torque required by a driver is calculated according to the current pedal opening, the vehicle speed, the gear and the engine speed, so that the acceleration, the deceleration and the vehicle speed controllability under various driving environments are ensured, and the driving quality of the vehicle is effectively improved. The method for determining the driver required driving torque on line is novel and practical, does not need to calibrate an off-line driver required driving torque map table, and reduces the development time and cost of the whole vehicle
Drawings
FIG. 1 is a graph of engine characteristics in an embodiment of the present invention;
FIG. 2 is a flow chart of a method for online determination of driver demanded drive torque in an embodiment of the present invention;
FIG. 3 is a balance diagram of vehicle driving force and running resistance in the embodiment of the invention;
fig. 4 is a graph of the required driving force of the accelerator pedal of 100% and 0% in the embodiment of the invention;
FIG. 5 is a diagram of a set of keypoints for insensitive regions and sensitive regions in an embodiment of the invention;
fig. 6 is a map of all point sets of accelerator pedal demand driving force in the embodiment of the invention;
fig. 7 is a driver accelerator pedal demand driving force characteristic map of the wheel end in the embodiment of the invention;
fig. 8 is a schematic block diagram of the driver required driving torque determination in the embodiment of the invention.
Detailed Description
The invention is further described with reference to the following figures and examples: the invention takes a car with an engine as a power source as an example, and the basic parameters of the car are as follows:
table 1: vehicle basic parameter table in the embodiment of the invention
Meaning of parameters Parameter value Unit of
Number of gear positions n 6
Transmission ratio of each gear of speed variator ig [4.212；2.637；1.8；1.386；1.0；0.772]
Transmission gear efficiency η [0.8777；0.885；0.9043；0.9138；0.9127；0.9058]
Main speed reducer transmission ratio i0 3.51
Radius of wheel r 0.350 m
Coefficient of rolling resistance f 0.1
Gravity of automobile G 1781*9.8 N
Coefficient of air resistance CD 0.381
Frontal area A 2.52 m^2
The engine characteristics in the embodiment of the invention are shown in fig. 1, and the flow of the driver required driving torque online determination method is shown in fig. 2;
the technical scheme adopted by the invention is that the method comprises the following steps:
step 1: determining a driving resistance curve and a maximum driving force curve; the specific implementation of the step is as follows: firstly, the driving resistance characteristic and the maximum driving curve of the vehicle are determined according to the basic parameters related to the driving dynamics of the automobile and the current vehicle state, and the maximum driving curve is determined as follows:
Figure GDA0002423170060000081
in the formula, TtqIs the maximum driving torque curve at the crankshaft end of the engine, igTo the transmission ratio of the variator, i0is the main reducer transmission ratio, is η the mechanical efficiency of the transmission system, and r is the automobile wheel radius;
the method for determining the driving resistance curve on the road surface with the gradient on line is as follows:
Figure GDA0002423170060000082
travel resistance curve on horizontal road surface: f2
Figure GDA0002423170060000083
Wherein G is the total gravity of the automobile, f is the rolling resistance coefficient, CDIs the air resistance coefficient, A is the windward area, u is the vehicle speed, theta is the gradient;
as can be seen from the above two equations, the driving resistance curve is a curve equation which exhibits a parabolic characteristic with speed, and the driving resistance curve on a road with a slope can be approximately regarded as being obtained by translating the driving resistance curve up and down on a horizontal road surface, as follows:
F1(u)＝F2(u)+constant (4)
the driving force F of the wheel end of the whole vehicle can be obtained through calculation by acquiring the output torque and gear information of the engine on the whole vehicle in real timexAnd obtaining the theoretical longitudinal acceleration a which the vehicle should have according to the running resistance curve equation of the horizontal road surfacex_expectLongitudinal acceleration a of the actual vehiclex_real，
Fx-F2(u)＝M*ax_expect(5)
Fx-F1(u)＝M*ax_real(6)
Wherein M is the mass of the vehicle, and simultaneous equations 3, 4, 5, and 6 can yield constant-M (a)x_expect-ax_real) To avoid miningWhen a single point is used for estimating the driving resistance curve, a large error exists, values of expected acceleration and actual acceleration of n points are continuously obtained within a certain period of time, n constant values are obtained through calculation, and a final constant value is obtained through averaging calculation
Figure GDA0002423170060000091
And then determining a running resistance curve when the road gradient exists on line:
Figure GDA0002423170060000092
the balance diagram of the running resistance curve and the maximum driving force curve is obtained by combining the running parameters of the engine and the automobile in the embodiment of the invention and is shown in FIG. 3;
step 2: determining a driving force curve required by a driver to the wheel end at the time of 100% of an accelerator pedal and a maximum vehicle speed u at the time of 100% of the accelerator pedalmax；
The step 2 is specifically realized as follows: according to the maximum driving force curve of the automobile, when the accelerator pedal is determined to be 100%, the required driving force curve of a driver to the wheel end is obtained by fitting a polynomial through a plurality of points, and the points are selected according to the following scheme:
(1) if the driving force curves of two adjacent gears have an intersection point, the intersection point is taken as one of the points to be subjected to polynomial fitting; if the driving force curves of two adjacent gears do not have an intersection point, a straight line perpendicular to an x axis is made at the position of the corresponding vehicle speed of the engine in the above one gear at the highest rotating speed, and the intersection point of the straight line and the next gear is used as one of points to be subjected to polynomial fitting; when the automobile has n gears, n-1 points can be determined, and a driving force request curve of the wheel end when the accelerator pedal is 100% is obtained by performing n-2 degree polynomial fitting on the n-1 points;
Faccpedal_100％(u)＝a0+a1*u+a2*u2...an-2*un-2(9)
in the formula, Faccpedal_100％(u) is a driving force request curve of the wheel end at 100% accelerator pedal, u is vehicle speed, a0,a1,......an-2Is a polynomial coefficient to be solved;
(2) simultaneously determining the maximum vehicle speed u under the current driving environment by simultaneous formula (1) and formula (2)max；
And step 3: determining a driving force curve required by a driver with 0% of opening of an accelerator pedal for a wheel end and a lowest stable vehicle speed;
the specific implementation of step 3 is as follows: determining the lowest stable vehicle speed of the automobile on a horizontal road surface according to a torque output curve under an idle throttle of the engine, simultaneously determining a driving force curve required by a driver to a wheel end under the condition of 0% pedal opening according to the torque output curve under the idle throttle of the engine, and recording the torque output curve under the idle throttle of the engine as Tengine_min(n), n represents the engine speed r/min,
(1) and converting the torque output curve under the idle throttle of the engine to the wheel end to obtain a driving force curve of the wheel end:
Figure GDA0002423170060000101
according to the following formula:
Figure GDA0002423170060000102
obtaining a torque output curve under an idle throttle of the engine, converting the torque output curve into a change curve of the driving force of a wheel end along with the vehicle speed:
Figure GDA0002423170060000103
in the formula ig1For first gear ratio of the transmission, i0is the main reducer transmission ratio, eta is the mechanical efficiency of the transmission system, r is the automobile wheel radius, and u represents the automobile speed;
(2) according to the horizontal road surface carThe lowest stable speed of the automobile is obtained from the intersection point of the driving resistance curve and the driving force curve, and the lowest stable speed (the intersection point of the driving force under the idle throttle and the resistance curve is the lowest stable speed) is obtained through simultaneous (3) and (10) and is recorded as uminWhile simultaneously adding Fwheel_min(u) as a driver demand drive force curve for the wheel end at 0% pedal opening;
combining the engine and the automobile running parameters in the embodiment of the invention, according to the step 2 and the required driving force curves of 100% and 0% of the accelerator pedal obtained in the step 3 and the highest vehicle speed, the lowest stable vehicle speed is shown in FIG. 4;
and 4, step 4: designing an accelerator pedal insensitive region; in order to ensure the easiness of the speed control, a pedal insensitive area is designed near the current driving resistance curve of the automobile, and the method is specifically realized as follows:
(1) setting a correspondence between an accelerator pedal opening and a stable vehicle speed
U is determined according to step 2 and step 3min、umaxDesigning m pedal opening degrees:
Figure GDA0002423170060000111
m is a positive integer greater than 2, and the expected stable speed of the automobile is u1/m,u2/m,…u(m-1)/mThe running resistance of the automobile corresponding to the stable speed is F1/m,F2/m...F(m-1)/m；
(2) Setting an upper limit and a lower limit of an insensitive region of an accelerator pedal
Opening degree of an accelerator pedal of
Figure GDA0002423170060000112
When k is an integer of 1 to m, the upper limit value coordinate and the lower limit value coordinate of the insensitive region are (u)k/m,Fk/m+ΔF)，(uk/m,Fk/mΔ F), in a similar manner, from u can be obtained1/mTo u(m-1)/mThe upper limit of the insensitive region of the whole vehicle speed interval is set as (u)1/m，F1/m+ΔF)，(u2/m，F2/m+ΔF),…(u(m-1)/m，F(m-1)/m+ Δ F), the point set of the lower limit of the insensitive region is (u)1/m,F1/m-ΔF)，(u2/m,F2/m-ΔF)，…(u(m-1)/m,F(m-1)/m- Δ F), by adjusting the value of Δ F, an adjustment of the accelerator pedal insensitivity of the pedal insensitive region is achieved;
and 5: designing an accelerator pedal sensitive area; the method comprises the following specific steps:
(1) designing a sensitive area above a driving resistance curve: determining the minimum stable vehicle speed uminThe corresponding running resistance is Ff+w(umin) Determining the maximum driving force F capable of being generated at the wheel end under the lowest stable vehicle speedt_max(umin) Then, the set of key points of the sensitive area above the driving resistance curve is designed as:
Figure GDA0002423170060000121
Figure GDA0002423170060000122
…
Figure GDA0002423170060000123
(2) the sensitive area below the driving resistance curve is designed as follows: the highest vehicle speed umaxSubstituting the formula (8) into the resistance curve formula to obtain the corresponding running resistance Ff+w(umax) Designing a key point set of a sensitive area below a driving resistance curve:
Figure GDA0002423170060000124
Figure GDA0002423170060000125
…
Figure GDA0002423170060000126
combining the engine and the automobile running parameters in the embodiment of the invention, according to the step 4, the step 5 can be used for distributing key point sets of the sensitive area and the insensitive area of the accelerator pedal, as shown in fig. 5;
step 6: determining a complete driving force map matrix table required by a driver at a wheel end on line; supplementing other spatial points on the basis of the determined key points in the step 4 and the step 5 to form a complete driving force map table required by the driver at the wheel end; the supplement method comprises the following steps: stabilized vehicle speed u according to design1/m,u2/m,…u(m-1)/mNext, the maximum driving force at the current vehicle speed is determined to be Fmax(u1/m)，Fmax(u2/m)...Fmax(u(m-1)/m) Taking the point as a key point of 100% of an accelerator pedal, linearly distributing driving force under other pedal opening degrees and the pedal opening degrees, supplementing point sets above and below an insensitive region of the accelerator pedal according to the method, and finally obtaining all point set distribution of the driving force required by the accelerator pedal; as shown in fig. 6, key points of the required driving force at the same pedal opening are connected to obtain a characteristic distribution diagram of the required driving force of the accelerator pedal required by the driver at the wheel end, as shown in fig. 7;
and 7: the driver's required driving torque at the output of the engine is calculated, and the determination principle is shown in fig. 8.
(1) Firstly, on the basis of a matrix table of driver required driving force map of the wheel end obtained by online determination in step 6, interpolating according to the current vehicle speed u and the accelerator opening acc _ pedal to obtain the driver required driving force F (u, acc _ pedal) of the wheel end under the current vehicle speed and the accelerator opening;
(2) the method comprises the following steps of calculating the required driving torque of a driver to the output end of an engine according to the required driving force of the driver at the wheel end, and concretely realizing the following steps: converting the driver required driving force of the wheel end under the current vehicle speed and the opening degree of an accelerator pedal to the output end of the engine according to the following formula to obtain the driver required driving torque of the output end of the engine:
Figure GDA0002423170060000131
where ig (n) is the transmission ratio at the current gear, i0 is the final drive ratio, η is the efficiency of the driveline, r is the wheel radius, T is the gear ratio of the transmission at the current gear, anddriverthe driver drives the torque for the demand of the output end of the engine under the current gear, the vehicle speed and the opening degree of an accelerator pedal.
The above description is only one embodiment of the present invention, and should not be taken as limiting the invention, and any modifications, equivalents, improvements, etc. made within the spirit and scope of the present invention are intended to be included therein.

Claims (8)

1. A method for determining driver demand drive torque on-line, comprising the steps of:
step 1: determining a driving resistance curve and a maximum driving force curve;
step 2: determining a driving force curve required by a driver to the wheel end at the time of 100% of an accelerator pedal and a maximum vehicle speed u at the time of 100% of the accelerator pedalmax；
And step 3: determining a driving force curve required by a driver with 0% of opening of an accelerator pedal for a wheel end and a lowest stable vehicle speed;
and 4, step 4: designing an accelerator pedal insensitive region;
and 5: designing an accelerator pedal sensitive area;
step 6: determining a complete driving force map matrix table required by a driver at a wheel end on line;
and 7: the driver's demanded drive torque at the output of the engine is calculated.
2. The on-line driver demand drive torque determination method according to claim 1, characterized in that: the specific implementation of the step 1 is as follows:
firstly, the driving resistance characteristic and the maximum driving curve of the vehicle are determined according to the basic parameters related to the driving dynamics of the automobile and the current vehicle state, and the maximum driving curve is determined as follows:
Figure FDA0002423170050000011
in the formula, TtqIs the maximum driving torque curve at the crankshaft end of the engine, igTo the transmission ratio of the variator, i0is the main reducer transmission ratio, is η the mechanical efficiency of the transmission system, and r is the automobile wheel radius;
the method for determining the driving resistance curve on the road surface with the gradient on line is as follows:
Figure FDA0002423170050000012
travel resistance curve on horizontal road surface: f2
Figure FDA0002423170050000013
Wherein G is the total gravity of the automobile, f is the rolling resistance coefficient, CDIs the air resistance coefficient, A is the windward area, u is the vehicle speed, theta is the gradient;
as can be seen from the above two equations, the driving resistance curve is a curve equation which exhibits a parabolic characteristic with speed, and the driving resistance curve on a road with a slope can be approximately regarded as being obtained by translating the driving resistance curve up and down on a horizontal road surface, as follows:
F1(u)＝F2(u)+constant (4)
the driving force F of the wheel end of the whole vehicle can be obtained through calculation by acquiring the output torque and gear information of the engine on the whole vehicle in real timexAnd obtaining the theoretical longitudinal acceleration a which the vehicle should have according to the running resistance curve equation of the horizontal road surfacex_expectLongitudinal acceleration a of the actual vehiclex_real，
Fx-F2(u)＝M*ax_expect(5)
Fx-F1(u)＝M*ax_real(6)
Wherein M is the mass of the vehicle, and simultaneous equations 3, 4, 5, and 6 can yield constant-M (a)x_expect-ax_real) In order to avoid large error when a single point is adopted for estimating the driving resistance curve, values of expected acceleration and actual acceleration of n points are continuously taken within a certain period of time, n constant values are calculated, and the average value is calculated to obtain the final constant value
Figure FDA0002423170050000021
And then determining a running resistance curve when the road gradient exists on line:
Figure FDA0002423170050000022
3. the on-line determination method of driver required driving torque according to claim 2, characterized in that the step 2 is implemented as follows:
according to the maximum driving force curve of the automobile, when the accelerator pedal is determined to be 100%, the required driving force curve of a driver to the wheel end is obtained by fitting a polynomial through a plurality of points, and the points are selected according to the following scheme:
(1) if the driving force curves of two adjacent gears have an intersection point, the intersection point is taken as one of the points to be subjected to polynomial fitting; if the driving force curves of two adjacent gears do not have an intersection point, a straight line perpendicular to an x axis is made at the position of the corresponding vehicle speed of the engine in the above one gear at the highest rotating speed, and the intersection point of the straight line and the next gear is used as one of points to be subjected to polynomial fitting; when the automobile has n gears, n-1 points can be determined, and a driving force request curve of the wheel end when the accelerator pedal is 100% is obtained by performing n-2 degree polynomial fitting on the n-1 points;
Faccpedal_100％(u)＝a0+a1*u+a2*u2...an-2*un-2(9)
in the formula, Faccpedal_100％(u) is a driving force request curve of the wheel end at 100% accelerator pedal, u is vehicle speed, a0,a1,......an-2Is a polynomial coefficient to be solved;
(2) simultaneously determining the maximum vehicle speed u under the current driving environment by simultaneous formula (1) and formula (2)max。
4. The on-line determination method of driver required driving torque according to claim 3, characterized in that the step 3 is implemented as follows:
determining the lowest stable vehicle speed of the automobile on a horizontal road surface according to a torque output curve under an idle throttle of the engine, simultaneously determining a driving force curve required by a driver to a wheel end under the condition of 0% pedal opening according to the torque output curve under the idle throttle of the engine, and recording the torque output curve under the idle throttle of the engine as Tengine_min(n), n represents the engine speed r/min,
(1) converting the torque output curve of the engine under the idle throttle valve to the wheel end to obtain the driving force curve of the wheel end
Figure FDA0002423170050000031
According to the following formula,
Figure FDA0002423170050000032
obtaining a change curve of the driving force of the wheel end along with the vehicle speed converted from a torque output curve under an idle throttle of the engine
Figure FDA0002423170050000033
In the formula ig1For first gear ratio of the transmission, i0is the transmission ratio of the main speed reducer and eta is the transmission ratioThe mechanical efficiency of the power train, r is the radius of the automobile wheel, and u represents the speed of the automobile;
(2) the lowest stable speed of the automobile is obtained according to the intersection point of the driving resistance curve and the driving force curve of the automobile on the horizontal road surface, the lowest stable speed is obtained through simultaneous operations (3) and (10) (the intersection point of the driving force and the resistance curve under the idle throttle is the lowest stable speed), and the lowest stable speed is recorded as uminWhile simultaneously adding Fwheel_min(u) as the driver's demanded drive force curve for the wheel end at 0% pedal opening.
5. The on-line determination method of driver required driving torque according to claim 4, characterized in that the step 4 is implemented as follows:
(1) setting a correspondence between an accelerator pedal opening and a stable vehicle speed
U is determined according to step 2 and step 3min、umaxDesigning m pedal opening degrees:
Figure FDA0002423170050000041
m is a positive integer greater than 2, and the expected stable speed of the automobile is u1/m,u2/m,…u(m-1)/mThe running resistance of the automobile corresponding to the stable speed is F1/m,F2/m...F(m-1)/m；
(2) Setting an upper limit and a lower limit of an insensitive region of an accelerator pedal
Opening degree of an accelerator pedal of
Figure FDA0002423170050000042
When k is an integer of 1 to m, the upper limit value coordinate and the lower limit value coordinate of the insensitive region are (u)k/m,Fk/m+ΔF)，(uk/m,Fk/mΔ F), in a similar manner, from u can be obtained1/mTo u(m-1)/mThe upper limit of the insensitive region of the whole vehicle speed interval is set as (u)1/m，F1/m+ΔF)，(u2/m，F2/m+ΔF),…(u(m-1)/m，F(m-1)/m+ Δ F), the point set of the lower limit of the insensitive region is (u)1/m,F1/m-ΔF)，(u2/m,F2/m-ΔF)，…(u(m-1)/m,F(m-1)/m- Δ F), the adjustment of the accelerator pedal insensitivity of the pedal insensitive region being achieved by adjusting the value of Δ F.
6. The on-line driver demand drive torque determination method as claimed in claim 5, wherein the step of step 5 is as follows:
(1) designing a sensitive area above a driving resistance curve: determining the minimum stable vehicle speed uminThe corresponding running resistance is Ff+w(umin) Determining the maximum driving force F capable of being generated at the wheel end under the lowest stable vehicle speedt_max(umin) Then, the set of key points of the sensitive area above the driving resistance curve is designed as:
Figure FDA0002423170050000043
(2) the sensitive area below the driving resistance curve is designed as follows: the highest vehicle speed umaxSubstituting the formula (8) into the resistance curve formula to obtain the corresponding running resistance Ff+w(umax) Designing a key point set of a sensitive area below a driving resistance curve:
Figure FDA0002423170050000051
7. the on-line driver demand drive torque determination method as claimed in claim 6, wherein said step 6 includes: supplementing other spatial points on the basis of the determined key points in the step 4 and the step 5 to form a complete driving force map table required by the driver at the wheel end; the supplement method comprises the following steps: stabilized vehicle speed u according to design1/m,u2/m,…u(m-1)/mNext, the maximum driving force at the current vehicle speed is determined to be Fmax(u1/m)，Fmax(u2/m)...Fmax(u(m-1)/m) The driving force under other pedal opening degrees and the pedal opening degrees are in linear distribution as a key point of 100% of the accelerator pedal, point sets above and below an insensitive region of the accelerator pedal are supplemented according to the method, and finally all point set distribution of the driving force required by the accelerator pedal is obtained.
8. The on-line driver demand drive torque determination method as claimed in claim 7, wherein said step 7 includes:
(1) firstly, on the basis of a matrix table of driver required driving force map of the wheel end obtained by online determination in step 6, interpolating according to the current vehicle speed u and the accelerator opening acc _ pedal to obtain the driver required driving force F (u, acc _ pedal) of the wheel end under the current vehicle speed and the accelerator opening;
(2) the method comprises the following steps of calculating the required driving torque of a driver to the output end of an engine according to the required driving force of the driver at the wheel end, and concretely realizing the following steps: converting the driver required driving force of the wheel end under the current vehicle speed and the opening degree of an accelerator pedal to the output end of the engine according to the following formula to obtain the driver required driving torque of the output end of the engine:
Figure FDA0002423170050000052
where ig (n) is the transmission ratio at the current gear, i0 is the final drive ratio, η is the efficiency of the driveline, r is the wheel radius, T is the gear ratio of the transmission at the current gear, anddriverthe driver drives the torque for the demand of the output end of the engine under the current gear, the vehicle speed and the opening degree of an accelerator pedal.
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