CN107009916B - Distributed driving electric automobile anti-skid control system and method considering driver intention - Google Patents

Distributed driving electric automobile anti-skid control system and method considering driver intention Download PDF

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CN107009916B
CN107009916B CN201710134285.1A CN201710134285A CN107009916B CN 107009916 B CN107009916 B CN 107009916B CN 201710134285 A CN201710134285 A CN 201710134285A CN 107009916 B CN107009916 B CN 107009916B
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wheel speed
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unit
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CN107009916A (en
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熊璐
李斌
冷搏
孙凯
余卓平
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Tongji 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
    • B60L2240/00—Control parameters of input or output; Target parameters
    • B60L2240/10—Vehicle control parameters
    • B60L2240/12—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
    • B60L2240/00—Control parameters of input or output; Target parameters
    • B60L2240/40—Drive Train control parameters
    • B60L2240/42—Drive Train control parameters related to electric machines
    • B60L2240/423—Torque
    • 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
    • B60L2240/00—Control parameters of input or output; Target parameters
    • B60L2240/40—Drive Train control parameters
    • B60L2240/46—Drive Train control parameters related to wheels
    • B60L2240/461—Speed
    • 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 a distributed driving electric automobile anti-skid control system and a distributed driving electric automobile anti-skid control method considering driver intention, wherein the system comprises a motor controller, a driver intention torque acquisition unit, a road adhesion coefficient estimation unit and a driving anti-skid control unit, wherein the motor controller is connected with driving motors of 4 wheels of a distributed driving electric automobile, the driver intention torque acquisition unit and the road adhesion coefficient estimation unit are both connected with the driving anti-skid control unit, and the driving anti-skid control unit is connected with the motor controller; the road adhesion coefficient estimator obtains a peak road adhesion coefficient of a wheel, the driver intention torque obtaining unit obtains a driver intention torque, and the driving antiskid controller controls and outputs a control torque to the motor controller according to the peak road adhesion coefficient and the driver intention torque. Compared with the prior art, the anti-skid control method comprehensively considers the intention of a driver, and is good in anti-skid control effect.

Description

Distributed driving electric automobile anti-skid control system and method considering driver intention
Technical Field
The invention relates to a distributed driving electric automobile anti-skid control system and method, in particular to a distributed driving electric automobile anti-skid control system and method considering driver intention.
Background
Driving an antiskid control system as one of basic systems for vehicle active safety has been a hot spot of vehicle dynamics research. Statistics shows that in the starting and accelerating processes of the vehicle, if the road adhesion coefficient is small, excessive slip of the driving wheels can be caused due to overlarge driving force, so that the driving performance of the vehicle is reduced, the slip is out of control under the condition of front wheel driving, and the slip of rear wheel driving causes drift. Particularly, when the rain, snow, hail and the hail road are frozen and the vehicle turns, the wheel slip easily causes the vehicle instability, and finally causes traffic accidents. The driving antiskid control system enables the vehicle to obtain larger longitudinal driving force and transverse adhesive force under severe road conditions or complex working conditions through a proper control algorithm according to the running working conditions of the vehicle, and the stability control effect of the vehicle under the limit working conditions is improved.
The method for driving the antiskid control at the present stage has various control strategies such as logic threshold value control, PID control, fuzzy control, optimal control, neural network control, sliding mode variable structure control and the like, and has advantages and disadvantages.
(1) The logic threshold value control does not relate to a specific mathematical model of a controlled system, so that the control of a nonlinear system is convenient to realize, but the control logic of the logic threshold value control is complex and has large fluctuation.
(2) The PID control can control the slip ratio to a set value, but requires different parameters to be set on different roads, so that the PID control is required to realize online adaptive adjustment.
(3) Fuzzy control carries out judgment and decision through fuzzy reasoning, and achieves the control effect. However, the method is difficult to establish the fuzzy control rule and difficult to debug.
(4) The optimal control solves the optimal index of the driving anti-skid control system according to the optimal principle, the effect of the optimal control depends on the precision of a mathematical model of the system, and the optimal control is difficult to realize in practical application.
(5) The sliding mode variable structure control enables the phase locus of the system control variable to slide to a control target along a switching line, the control method has strong robustness, but near the sliding mode surface, high-frequency jitter can be generated by control torque.
In addition, in the existing method, a layered control algorithm is usually adopted, wherein a distribution layer gives a distribution torque to drive the anti-skid control system to output a control torque, so that a control algorithm intervention mechanism needs to be set to judge when to control the driving motor through the distribution torque, and when to control the driving motor through accessing the anti-skid control system, so that the control efficiency is low.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provide an antiskid control system and method for a distributed driving electric automobile by considering the intention of a driver.
The purpose of the invention can be realized by the following technical scheme:
a distributed driving electric automobile anti-skid control system considering driver intention comprises a motor controller, a driver intention torque acquisition unit, a road adhesion coefficient estimation unit and a driving anti-skid control unit, wherein the motor controller is connected with driving motors of 4 wheels of a distributed driving electric automobile;
the road adhesion coefficient estimation unit acquires a peak road adhesion coefficient of a wheel, the driver intention torque acquisition unit acquires a driver intention torque, and the drive antiskid control unit controls and outputs a control torque to the motor controller according to the peak road adhesion coefficient and the driver intention torque.
The driver intention torque acquisition unit comprises a position sensor for measuring the position of an accelerator pedal and a driver intention torque calculator, wherein the driver intention torque calculator calculates and obtains the driver intention torque T according to the movement displacement of the accelerator pedal measured by the position sensord。
The road surface adhesion coefficient estimation unit include road surface peak value adhesion coefficient estimator and vertical force estimator, road surface peak value adhesion coefficient estimator input be connected with speed sensor, the fast unit of acquireing of wheel, torque and acquire unit and vertical force estimator, road surface peak value adhesion coefficient estimator output is connected the drive antiskid control unit, speed sensor be used for measuring whole car speed, the fast unit of acquireing of wheel be used for acquireing the actual wheel speed of 4 wheels, the torque acquire the motor torque that the unit is used for acquireing the driving motor of 4 wheels, vertical force estimator be used for estimating the vertical force of 4 wheels, road surface peak value adhesion coefficient estimator estimate the road surface peak value adhesion coefficient of every wheel according to whole car speed, the fast, motor torque of actual wheel and the vertical force estimation of wheel.
The vertical force estimator comprises the following specific steps:
Figure GDA0002300450070000031
Figure GDA0002300450070000032
Figure GDA0002300450070000033
Figure GDA0002300450070000034
Figure GDA0002300450070000035
and
Figure GDA0002300450070000036
are the vertical forces of the left front wheel, the right front wheel, the left rear wheel and the right rear wheel respectively, m is the mass of the whole vehicle, g is the gravity acceleration, l is the wheelbase and lfIs the distance from the center of mass to the front axis,/rIs the distance h from the center of mass to the rear axlegIs the height of the center of mass, axFor longitudinal acceleration, ayIs the lateral acceleration.
The road surface peak adhesion coefficient estimator specifically comprises:
Figure GDA0002300450070000037
wherein z is an intermediate variable, I is equivalent rotational inertia of the wheel, and TmIs the motor torque, r is the wheel rolling radius,
Figure GDA0002300450070000038
as wheel longitudinal force estimate, FzThe wheel vertical force estimated for the vertical force estimator,
Figure GDA0002300450070000039
for the road surface peak adhesion coefficient estimation value, λ is the wheel slip ratio, λ is (ω r-v)/v, ω is the actual wheel speed acquired by the wheel speed acquisition subunit, v is the vehicle speed measured by the vehicle speed sensor, and θ is*Is an equation of equation
Figure GDA00023004500700000310
Numerical solution of (a), k1And γ is the estimator design parameter, k1And gamma are constants, mu (lambda, theta) is a modified Burckhardt tire model,
Figure GDA00023004500700000311
is a middle order of μ (λ, θ)
Figure GDA00023004500700000312
The resulting model function, in particular, μ (λ, θ) is:
Figure GDA00023004500700000313
wherein theta is the peak adhesion coefficient of the road surface, and theta2、θ3、θ4And theta5Are all constant parameters, exp is an exponential function with a natural constant e as a base, and sgn is a sign function.
The anti-skid driving control unit comprises an optimal slip rate acquisition unit, a reference wheel speed calculation unit, a wheel speed difference calculation unit and an anti-saturation integral slip mode variable structure controller based on the intention of a driver, wherein the input end of the optimal slip rate acquisition unit is connected with a road surface adhesion coefficient estimation unit, the output end of the optimal slip rate acquisition unit is connected with the input end of the reference wheel speed calculation unit, the input end of the reference wheel speed calculation unit is also connected with a vehicle speed sensor, the output end of the reference wheel speed calculation unit is connected with the negative input end of the wheel speed difference calculation unit, the positive input end of the wheel speed difference calculation unit is connected with the wheel speed acquisition unit, the output end of the wheel speed difference calculation unit is connected with the input end of the anti-saturation integral slip mode variable structure controller based on the intention of the driver, and the input end of the anti-saturation integral, the output end of the anti-saturation integral sliding mode variable structure controller based on the intention of a driver is connected with a motor controller, and the optimal sliding rate acquisition unit is a preset lookup table in which the peak road adhesion coefficients and the optimal sliding rates are in one-to-one correspondence;
the optimal slip rate obtaining unit searches for a corresponding optimal slip rate according to road surface peak value adhesion coefficients of 4 wheels obtained by the road surface adhesion coefficient estimating unit, the reference wheel speed calculating unit calculates the reference wheel speed of each wheel according to the optimal slip rate and the vehicle speed obtained by the vehicle speed sensor, the wheel speed difference calculating unit calculates the difference value between the actual wheel speed obtained by the wheel speed obtaining unit and the reference wheel speed calculated by the reference wheel speed calculating unit, and the anti-saturation integral slip mode variable structure controller based on the intention of a driver calculates and obtains a control moment according to the wheel speed difference value and the intention moment of the driver obtained by the intention moment obtaining unit and inputs the control moment to the motor controller.
The reference wheel speed calculating unit is specifically as follows:
Figure GDA0002300450070000041
wherein, ω isrFor reference wheel speed, λrFor optimum slip ratio, v is the vehicle speed and r is the wheel rolling radius.
The anti-saturation integral sliding mode variable structure controller based on the intention of the driver specifically comprises the following steps:
Figure GDA0002300450070000042
wherein, TdTorque intended for driver, TctrFor the control torque output by the anti-saturation integral sliding mode variable structure controller based on the intention of the driver,
Figure GDA0002300450070000043
is the upper limit of the motor torque, rho is a conditional integral term, k0For integral gain, delta is the boundary layer thickness near the switching curved surface of sliding mode control, sat is a saturation function, and e is omega-omegarω is the actual wheel speed, ωrIs referred to as the wheel speed.
A control method of the above slip control system for a distributed drive electric vehicle taking into consideration the driver's intention, the method comprising the steps of:
(1) acquiring actual wheel speeds omega of 4 wheels, corresponding torque of a driving motor and the vehicle speed v of the whole vehicle in real time;
(2) acquiring the intention torque of a driver in real time;
(3) inputting the data acquired in the step (1) into a road adhesion coefficient estimation unit to obtain road peak adhesion coefficients corresponding to 4 wheels;
(4) searching a preset lookup table in which the peak road adhesion coefficients correspond to the optimal slip rates one by one to obtain the optimal slip rates matched with the peak road adhesion coefficients obtained in the step (3);
(5) calculating the reference wheel speed omega corresponding to each wheel according to the optimal slip rate and the vehicle speed vr；
(6) The actual wheel speed omega and the reference wheel speed omega are comparedrIs equal to ω - ωrInputting the driver intention torque acquired in the step (2) into a pre-designed anti-saturation integral sliding mode variable structure controller based on the driver intention to obtain a control torque;
(7) the control torque is input to a motor controller to control the driving motors of the 4 wheels.
The driver intention torque in the step (2) is obtained by the following method: t isdKd, where K is a constant parameter determined from different vehicles, and d is the pedal movement displacement measured by the accelerator pedal position sensor.
Compared with the prior art, the invention has the following advantages:
(1) the invention sets the driver intention torque acquisition unit to acquire the driver intention torque in real time, and meanwhile, the drive antiskid control unit can effectively adjust the control torque of the drive motor according to the driver intention torque and the road surface peak value adhesion coefficient, and when the driver intention is considered, the optimal drive can be realized without setting a control algorithm intervention mechanism, thereby improving the control efficiency.
(2) According to the anti-saturation integral sliding mode variable structure controller based on the intention of a driver, a boundary layer is added near a switching curved surface of sliding mode control, an existing control rule is selected outside the boundary layer, the boundary layer is guaranteed to be attractive, so that the boundary layer is a constant set, all track lines starting from the boundary layer can still stay in the boundary layer, a condition integral controller is adopted in the boundary layer to form the improved sliding mode controller, high-frequency jitter is eliminated as far as possible while the robustness is guaranteed, the control accuracy of the controller is guaranteed, and the anti-slip control effect is improved;
(3) an anti-windup integral slip mode variable architecture controller based on driver intent is such that when the driver intent torque is insufficient to slip the wheels, the controller will eventually generate the same torque as the driver demand. When the driver's intended torque is greater than the road peak attachment torque, the controller may cause the wheels to operate at the target slip rate to achieve optimal drive.
(4) According to the invention, the driver intention torque is obtained by obtaining pedal position information through the accelerator pedal position sensor and calculating different constant parameters K set by different vehicles, so that comprehensive control can be rapidly and conveniently carried out according to the intention of the driver, and the control efficiency is improved.
Drawings
FIG. 1 is a block diagram of a distributed drive electric vehicle antiskid control system of the present invention considering driver's intention;
fig. 2 is a one-to-one correspondence graph of the peak road adhesion coefficient and the optimal slip ratio.
In the figure, 1 is a motor controller, 2 is a driver intention torque acquisition unit, 3 is a vehicle speed sensor, 4 is a vertical force estimator, 5 is a road surface peak adhesion coefficient estimator, 6 is an optimal slip rate acquisition unit, 7 is a reference wheel speed calculation unit, and 8 is an anti-saturation integral slip mode variable structure controller based on the driver intention.
Detailed Description
The invention is described in detail below with reference to the figures and specific embodiments.
Examples
As shown in fig. 1, a distributed driving electric vehicle antiskid control system considering driver's intention, the system includes a motor controller 1, the motor controller 1 is connected with driving motors of 4 wheels of the distributed driving electric vehicle, the system also includes a driver's intention torque acquisition unit 2, a road adhesion coefficient estimation unit and a driving antiskid control unit, the driver's intention torque acquisition unit 2 and the road adhesion coefficient estimation unit are both connected with the driving antiskid control unit, the driving antiskid control unit is connected with the motor controller 1;
the road adhesion coefficient estimator obtains a peak road adhesion coefficient of wheels, the driver intention torque obtaining unit 2 obtains a driver intention torque, and the driving antiskid controller controls and outputs a control torque to the motor controller 1 according to the peak road adhesion coefficient and the driver intention torque.
The driver intention torque acquisition unit 2 includes a position sensor for measuring the position of the accelerator pedal and a driver intention torque calculator that calculates a driver intention torque T from the movement displacement of the accelerator pedal measured by the position sensord. The road surface adhesion coefficient estimation unit comprises a road surface peak adhesion coefficient estimator 5 and a vertical force estimator 4, the input end of the road surface peak adhesion coefficient estimator 5 is connected with a vehicle speed sensor 3, a wheel speed acquisition unit, a torque acquisition unit and the vertical force estimator 4, the output end of the road surface peak adhesion coefficient estimator 5 is connected with a drive anti-skidding control unit, the vehicle speed sensor 3 is used for measuring the speed of the whole vehicle, the wheel speed acquisition unit is used for acquiring the actual wheel speed of 4 wheels, the torque acquisition unit is used for acquiring the motor torque of a drive motor of the 4 wheels, the vertical force estimator 4 is used for estimating the vertical force of the 4 wheels, and the road surface peak adhesion coefficient estimator 5 estimates the road surface peak adhesion coefficient of each wheel according to the speed of the whole vehicle, the actual wheel.
The vertical force estimator 4 is specifically:
Figure GDA0002300450070000071
Figure GDA0002300450070000072
and
Figure GDA0002300450070000073
are respectively the vertical forces of the left front wheel, the right front wheel, the left rear wheel and the right rear wheel, m is the mass of the whole vehicle, and g is the gravity accelerationL is the wheelbase, lfIs the distance from the center of mass to the front axis,/rIs the distance h from the center of mass to the rear axlegIs the height of the center of mass, axFor longitudinal acceleration, ayIs the lateral acceleration.
The road surface peak adhesion coefficient estimator 5 is specifically:
Figure GDA0002300450070000074
wherein z is an intermediate variable, I is equivalent rotational inertia of the wheel, and TmIs the motor torque, r is the wheel rolling radius,
Figure GDA0002300450070000075
as wheel longitudinal force estimate, FzFor the wheel vertical force estimated by the vertical force estimator 4,
Figure GDA0002300450070000076
for the road surface peak adhesion coefficient estimation value, λ is the wheel slip ratio, λ is (ω r-v)/v, ω is the actual wheel speed acquired by the wheel speed acquisition subunit, v is the vehicle speed measured by the vehicle speed sensor 3, and θ is*Is an equation of equation
Figure GDA0002300450070000077
Numerical solution of (a), k1And γ is the estimator design parameter, k1And gamma are constants, mu (lambda, theta) is a modified Burckhardt tire model,
Figure GDA0002300450070000078
is a middle order of μ (λ, θ)
Figure GDA0002300450070000079
The resulting model function, in particular, μ (λ, θ) is:
Figure GDA00023004500700000710
wherein theta is the peak adhesion coefficient of the road surface, and theta2、θ3、θ4And theta5Are all constant parameters, exp is an exponential function with a natural constant e as a base, and sgn is a sign function.
The driving anti-skid control unit comprises an optimal slip rate acquisition unit 6, a reference wheel speed calculation unit 7, a wheel speed difference value calculation unit and an anti-saturation integral slip mode variable structure controller 8 based on the intention of a driver based on the intention of the driver, the input end of the optimal slip rate acquisition unit 6 is connected with a road surface adhesion coefficient estimation unit, the output end of the optimal slip rate acquisition unit 6 is connected with the input end of the reference wheel speed calculation unit 7, the input end of the reference wheel speed calculation unit 7 is also connected with a vehicle speed sensor 3, the output end of the reference wheel speed calculation unit 7 is connected with the negative input end of the wheel speed difference value calculation unit, the positive input end of the wheel speed difference value calculation unit is connected with the wheel speed acquisition unit, the output end of the wheel speed difference value calculation unit is connected with the input end of the anti-saturation integral slip mode variable structure controller 8 based on the intention of the, the output end of an anti-saturation integral sliding mode variable structure controller 8 based on the intention of a driver is connected with a motor controller 1, and an optimal sliding rate acquisition unit 6 is a preset lookup table in which the peak road adhesion coefficients and the optimal sliding rates are in one-to-one correspondence; the optimal slip rate obtaining unit 6 searches for a corresponding optimal slip rate according to road surface peak adhesion coefficients of 4 wheels obtained by the road surface adhesion coefficient estimating unit, the reference wheel speed calculating unit 7 calculates a reference wheel speed of each wheel according to the optimal slip rate and a vehicle speed obtained by the vehicle speed sensor 3, the wheel speed difference calculating unit calculates a difference value between an actual wheel speed obtained by the wheel speed obtaining unit and the reference wheel speed calculated by the reference wheel speed calculating unit 7, and the anti-saturation integral slip mode variable structure controller 8 based on the intention of the driver calculates a derived control moment according to the wheel speed difference value and the intention moment of the driver obtained by the driver intention moment obtaining unit 2 and inputs the derived control moment to the motor controller 1.
And correcting the reference slip rate according to the updating result of the road surface peak value adhesion coefficient estimated by the road surface estimator. Therefore, the self-adaptive adjustment of slip ratio control under different road surface peak value adhesion coefficients can be realized, and the specific method comprises the following steps:
utilizing an improved Burckhardt tire model to conduct derivation on the slip ratio to obtain:
Figure GDA0002300450070000081
and the value of lambda when the formula is 0 is the optimal slip ratio under the road surface. Parameters representing peak adhesion coefficient of road surface
Figure GDA0002300450070000085
And (3) carrying out value calculation from 0.1 to 1 at intervals of 0.1 to obtain a one-to-one corresponding curve chart of the peak road adhesion coefficient and the optimal slip ratio shown in fig. 2, and then manufacturing a preset one-to-one corresponding lookup table of the peak road adhesion coefficient and the optimal slip ratio according to the curve chart.
The reference wheel speed calculation unit 7 is specifically:
Figure GDA0002300450070000083
wherein, ω isrFor reference wheel speed, λrFor optimum slip ratio, v is the vehicle speed and r is the wheel rolling radius.
The anti-saturation integral sliding mode variable structure controller 8 based on the intention of the driver is specifically as follows:
Figure GDA0002300450070000084
wherein, TdTorque intended for driver, TctrFor the control torque output by the anti-saturation integral sliding mode variable structure controller 8 based on the intention of the driver,
Figure GDA0002300450070000086
is the upper limit of the motor torque, rho is a conditional integral term, k0For integral gain, delta is the boundary layer thickness near the switching curved surface of sliding mode control, sat is a saturation function, and e is omega-omegarω is the actual wheel speed, ωrIs referred to as the wheel speed.
Note T*For a fixed reference slip ratio lambdarefThe steady state motor torque of (2) is thend|≤|T*I, it is known that the final wheel will operate on the linear segment of the μ - λ curve. Because if initially operated in the stable region, and | Td|≤|T*If the wheel torque reaches the peak longitudinal force of the road surface, the wheel torque will stay in the steady state region, where e is less than 0, so that finally rho is-delta/k0So finally | e + k0Rho | ≧ δ, then Tctr＝Td. On the other hand, if the initial wheel is operating in an unstable region, e may not always be greater than 0. If e is always greater than 0, the final ρ is δ/k0Then finally TctrAnd thus the wheel will eventually return to the stable region, which is contradictory to e always being greater than 0. There is therefore a time e ≦ 0 after which | T is reusedd|≤|T*I, it is known that the wheel will return to the stable region.
An anti-saturation integral slip mode variable architecture controller that takes into account driver intent is such that when the driver-intended torque is insufficient to slip the wheels, the controller will eventually generate the same torque as the driver demand. When the driver's intended torque is greater than the road peak attachment torque, the controller may cause the wheels to operate at the target slip rate to achieve optimal drive.
A control method using the above-described distributed drive electric vehicle antiskid control system taking into account the driver's intention, the method comprising the steps of:
(1) acquiring actual wheel speeds omega of 4 wheels, corresponding torque of a driving motor and the vehicle speed v of the whole vehicle in real time;
(2) acquiring the intention torque of a driver in real time;
(3) inputting the data acquired in the step (1) into a road adhesion coefficient estimation unit to obtain road peak adhesion coefficients corresponding to 4 wheels;
(4) searching a preset lookup table in which the peak road adhesion coefficients correspond to the optimal slip rates one by one to obtain the optimal slip rates matched with the peak road adhesion coefficients obtained in the step (3);
(5) calculating the reference wheel speed omega corresponding to each wheel according to the optimal slip rate and the vehicle speed vr；
(6) The actual wheel speed omega and the reference wheel speed omega are comparedrIs equal to ω - ωrInputting the driver intention torque acquired in the step (2) into a pre-designed anti-saturation integral sliding mode variable structure controller 8 based on the driver intention to obtain a control torque;
(7) the control torque is input to the motor controller 1 to control the drive motors of the 4 wheels.
The driver intention torque in the step (2) is obtained by the following method: t isdKd, where K is a constant parameter determined from different vehicles, and d is the pedal movement displacement measured by the accelerator pedal position sensor.

Claims (7)

1. A distributed driving electric automobile antiskid control system considering driver intention, the system comprises a motor controller (1), the motor controller (1) is connected with driving motors of 4 wheels of a distributed driving electric automobile, the system is characterized by also comprising a driver intention torque acquisition unit (2), a road adhesion coefficient estimation unit and a driving antiskid control unit, the driver intention torque acquisition unit (2) and the road adhesion coefficient estimation unit are both connected with the driving antiskid control unit, and the driving antiskid control unit is connected with the motor controller (1);
the road adhesion coefficient estimation unit acquires a peak road adhesion coefficient of wheels, the driver intention moment acquisition unit (2) acquires a driver intention moment, and the drive antiskid control unit controls and outputs a control moment to the motor controller (1) according to the peak road adhesion coefficient and the driver intention moment;
the road adhesion coefficient estimation unit comprises a road peak adhesion coefficient estimator (5) and a vertical force estimator (4), the input end of the road surface peak value adhesion coefficient estimator (5) is connected with a vehicle speed sensor (3), a wheel speed acquisition unit, a torque acquisition unit and a vertical force estimator (4), the output end of the road surface peak value adhesion coefficient estimator (5) is connected with a driving antiskid control unit, the vehicle speed sensor (3) is used for measuring the vehicle speed of the whole vehicle, the wheel speed acquisition unit is used for acquiring the actual wheel speeds of 4 wheels, the torque acquisition unit is used for acquiring motor torques of driving motors of 4 wheels, the vertical force estimator (4) is used for estimating vertical forces of the 4 wheels, the road surface peak value adhesion coefficient estimator (5) estimates the road surface peak value adhesion coefficient of each wheel according to the vehicle speed of the whole vehicle, the actual wheel speed, the motor torque and the vertical force of the wheels;
the anti-skid driving control unit comprises an optimal slip rate acquisition unit (6), a reference wheel speed calculation unit (7), a wheel speed difference value calculation unit and an anti-saturation integral slip mode variable structure controller (8) based on the intention of a driver, wherein the input end of the optimal slip rate acquisition unit (6) is connected with a road adhesion coefficient estimation unit, the output end of the optimal slip rate acquisition unit (6) is connected with the input end of the reference wheel speed calculation unit (7), the input end of the reference wheel speed calculation unit (7) is also connected with a vehicle speed sensor (3), the output end of the reference wheel speed calculation unit (7) is connected with the negative input end of the wheel speed difference value calculation unit, the positive input end of the wheel speed difference value calculation unit is connected with the wheel speed acquisition unit, the output end of the wheel speed difference value calculation unit is connected with the input end of the anti-saturation integral slip mode variable structure controller (8) based on the intention of the driver, and the The acquisition unit (2) is used for connecting the output end of the anti-saturation integral sliding mode variable structure controller (8) based on the intention of a driver with the motor controller (1), and the optimal sliding rate acquisition unit (6) is a preset lookup table in which the peak road adhesion coefficients and the optimal sliding rates are in one-to-one correspondence;
an optimal slip rate obtaining unit (6) searches for a corresponding optimal slip rate according to road surface peak adhesion coefficients of 4 wheels obtained by a road surface adhesion coefficient estimation unit, a reference wheel speed calculation unit (7) calculates a reference wheel speed of each wheel according to the optimal slip rate and a vehicle speed obtained by a vehicle speed sensor (3), a wheel speed difference calculation unit calculates a difference value between an actual wheel speed obtained by the wheel speed obtaining unit and the reference wheel speed calculated by the reference wheel speed calculation unit (7), and an anti-saturation integral slip mode variable structure controller (8) based on the intention of a driver calculates and obtains a control moment according to the wheel speed difference value and the intention moment of the driver obtained by the intention moment obtaining unit (2) and inputs the control moment into a motor controller (1).
2. The antiskid control system of a distributed drive electric vehicle considering driver's intention according to claim 1, wherein the driver's intention torque obtaining unit (2) includes a position sensor for measuring a position of an accelerator pedal and a driver's intention torque calculator, and the driver's intention torque calculator calculates the driver's intention torque T based on a movement displacement of the accelerator pedal measured by the position sensord。
3. The antiskid control system for a distributed drive electric vehicle considering driver's intention according to claim 1, wherein the road surface peak adhesion coefficient estimator (5) is embodied as:
Figure FDA0002316681750000021
wherein z is an intermediate variable, I is equivalent rotational inertia of the wheel, and TmIs the motor torque, r is the wheel rolling radius,
Figure FDA0002316681750000022
as wheel longitudinal force estimate, FzFor the wheel vertical force estimated by the vertical force estimator (4),
Figure FDA0002316681750000023
for the road surface peak adhesion coefficient estimation value, λ is a wheel slip ratio, λ is (ω r-v)/v, ω is an actual wheel speed acquired by the wheel speed acquisition subunit, v is a vehicle speed measured by the vehicle speed sensor (3), and θ is*Is an equation of equation
Figure FDA0002316681750000024
Numerical solution of (a), k1And γ is the estimator design parameter, k1And gamma are constants, mu (lambda, theta) is a modified Burckhardt tire model,
Figure FDA0002316681750000025
is a middle order of μ (λ, θ)
Figure FDA0002316681750000026
The resulting model function, in particular, μ (λ, θ) is:
Figure FDA0002316681750000027
wherein theta is the peak adhesion coefficient of the road surface, and theta2、θ3、θ4And theta5Are all constant parameters, exp is an exponential function with a natural constant e as a base, and sgn is a sign function.
4. The antiskid control system for a distributed drive electric vehicle considering driver's intention according to claim 1, wherein the reference wheel speed calculating unit (7) is embodied as:
Figure FDA0002316681750000031
wherein, ω isrFor reference wheel speed, λrFor optimum slip ratio, v is the vehicle speed and r is the wheel rolling radius.
5. The antiskid control system of a distributed drive electric vehicle considering driver's intention according to claim 1, wherein the driver intention-based anti-saturation integral slip mode variable structure controller (8) is embodied as:
Figure FDA0002316681750000032
wherein, TdTorque intended for driver, TctrThe control torque outputted by the anti-saturation integral sliding mode variable structure controller (8) based on the intention of a driver,
Figure FDA0002316681750000033
is the upper limit of motor torque, and rho is the conditional productSubentry, k0For integral gain, delta is the boundary layer thickness near the switching curved surface of sliding mode control, sat is a saturation function, and e is omega-omegarω is the actual wheel speed, ωrIs referred to as the wheel speed.
6. A control method using the antiskid control system of the distributed drive electric vehicle considering the driver's intention according to any one of claims 1 to 5, characterized in that the method comprises the steps of:
(1) acquiring actual wheel speeds omega of 4 wheels, corresponding torque of a driving motor and the vehicle speed v of the whole vehicle in real time;
(2) acquiring the intention torque of a driver in real time;
(3) inputting the data acquired in the step (1) into a road adhesion coefficient estimation unit to obtain road peak adhesion coefficients corresponding to 4 wheels;
(4) searching a preset lookup table in which the peak road adhesion coefficients correspond to the optimal slip rates one by one to obtain the optimal slip rates matched with the peak road adhesion coefficients obtained in the step (3);
(5) calculating the reference wheel speed omega corresponding to each wheel according to the optimal slip rate and the vehicle speed vr；
(6) The actual wheel speed omega and the reference wheel speed omega are comparedrIs equal to ω - ωrInputting the driver intention torque acquired in the step (2) into a pre-designed anti-saturation integral sliding mode variable structure controller (8) based on the driver intention to obtain a control torque;
(7) the control torque is inputted to a motor controller (1) to control the driving motors of the 4 wheels.
7. The control method according to claim 6, characterized in that the driver's intention torque in step (2) is obtained by: t isdKd, where K is a constant parameter determined from different vehicles, and d is the pedal movement displacement measured by the accelerator pedal position sensor.
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