CN111376906A - Corrected target anti-skid control method for heavy hub motor vehicle - Google Patents
Corrected target anti-skid control method for heavy hub motor vehicle Download PDFInfo
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60W—CONJOINT CONTROL OF VEHICLE SUB-UNITS OF DIFFERENT TYPE OR DIFFERENT FUNCTION; CONTROL SYSTEMS SPECIALLY ADAPTED FOR HYBRID VEHICLES; ROAD VEHICLE DRIVE CONTROL SYSTEMS FOR PURPOSES NOT RELATED TO THE CONTROL OF A PARTICULAR SUB-UNIT
- B60W30/00—Purposes of road vehicle drive control systems not related to the control of a particular sub-unit, e.g. of systems using conjoint control of vehicle sub-units
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- B60W30/18172—Preventing, or responsive to skidding of wheels
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60W—CONJOINT CONTROL OF VEHICLE SUB-UNITS OF DIFFERENT TYPE OR DIFFERENT FUNCTION; CONTROL SYSTEMS SPECIALLY ADAPTED FOR HYBRID VEHICLES; ROAD VEHICLE DRIVE CONTROL SYSTEMS FOR PURPOSES NOT RELATED TO THE CONTROL OF A PARTICULAR SUB-UNIT
- B60W30/00—Purposes of road vehicle drive control systems not related to the control of a particular sub-unit, e.g. of systems using conjoint control of vehicle sub-units
- B60W30/02—Control of vehicle driving stability
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60W—CONJOINT CONTROL OF VEHICLE SUB-UNITS OF DIFFERENT TYPE OR DIFFERENT FUNCTION; CONTROL SYSTEMS SPECIALLY ADAPTED FOR HYBRID VEHICLES; ROAD VEHICLE DRIVE CONTROL SYSTEMS FOR PURPOSES NOT RELATED TO THE CONTROL OF A PARTICULAR SUB-UNIT
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Abstract
The invention provides a corrected target anti-skid control for a heavy hub motor vehicle. The method comprises the steps of calculating the vehicle speed and the yaw angular velocity according to the rotating speed of a driven wheel and the rotating angle of a steering wheel, performing primary antiskid control by using proportional differential control of a correction target, and redistributing the torque according to the vehicle speed and the skidding degree to realize antiskid control of the vehicle. The invention can overcome the control delay of the heavy vehicle in the anti-skid control and ensure that the phenomenon of overshoot oscillation does not occur in the rotating speed of the wheels. The invention can simultaneously cover the anti-skid control of the wheel hub motor driven vehicle under the braking and driving working conditions, and can also ensure the yaw stability of the running on the ice and snow curve. Meanwhile, the method does not depend on the mass parameters of the vehicle, the total mass and the mass center position of the whole vehicle are greatly changed due to the change of the mass of the goods of heavy vehicles such as a passenger car, a truck and the like because the number of passengers is changed, and the influence of the change of the parameters can be effectively avoided.
Description
Technical Field
The invention belongs to the field of vehicle dynamics control, and particularly relates to a corrected target anti-skid control method for a heavy hub motor vehicle.
Technical Field
In order to prevent a vehicle from slipping when the vehicle is running on a low-adhesion road such as a snow area or an ice surface and to ensure driving safety on the ice and snow road, it is necessary to add drive antiskid control to a general vehicle. By adjusting the output torque of the engine or the engagement opening of the clutch, the drive anti-skid control is widely applied to both the traditional internal combustion engine vehicle and the electric vehicle. For a pure electric vehicle driven by an in-wheel motor, the driving torque of different in-wheel motors is generally adjusted to prevent each wheel from slipping, so that the vehicle can safely run on an ice and snow road, and the stability of the vehicle running on a split road and an ice and snow curve can be ensured by coordinating the torque between the in-wheel motors. On a passenger vehicle driven by a common hub motor, the driving antiskid control is verified by practical experiments and is practically applied.
For heavy vehicles such as passenger cars and trucks driven by hub motors, the motors and the vehicles have larger delay compared with common passenger vehicles due to larger inertia, so that the control method of the common hub motor driven passenger vehicles has the problems of slower change of control quantity such as wheel rotation speed and the like and larger delay between the control target rotation speed and the actual wheel rotation speed when being used for the heavy vehicles. In order to overcome the wheel speed static difference during skidding, the existing antiskid control generally introduces integral control, which causes new problems such as overshoot and the like for heavy vehicles with large inertia. When the in-wheel motor driven vehicle slides at a high speed or is braked to run, a motor braking method is generally needed, and when the motor is braked, the wheel dragging phenomenon can be caused by braking torque, so that the braking anti-skid control of the in-wheel motor driven vehicle is required to be added on the existing driving anti-skid control. Secondly, heavy vehicles such as passenger cars and trucks can change the total mass of the whole vehicle greatly due to the change of the number of passengers and the change of the mass of cargos, and methods based on mass parameters, such as methods for estimating ground force and methods for estimating adhesion coefficient, are not suitable for controlling medium-sized vehicles.
Disclosure of Invention
The invention provides a corrected target anti-skid control method for a heavy hub motor vehicle, aiming at the problem that the prior art can not be suitable for heavy vehicles, the method can ensure that the heavy vehicle does not skid during driving and braking running on an ice and snow road, has yaw stability during running on an opposite road or an ice and snow curve, improves the control delay of the heavy vehicle, does not depend on vehicle quality parameters, and has better control effect under the working conditions of no load and full load of a passenger car and a truck.
In order to achieve the purpose, the invention adopts the following technical scheme:
the invention provides a corrected target anti-skid control method for a heavy hub motor vehicle, which is characterized by comprising an internal loop and an external loop, wherein a variable of the internal loop is represented by j, j is 1,2, …, N and N are the maximum times of the internal loop, the N times of internal loop are calculated as a control step length of the external loop, and (i, j) in the following formula represents the j control in the ith step control; the front wheels of the vehicle are all driven wheels, and the rear wheels are all driving wheels; the corrected target antiskid control method comprises the following steps:
1) control initialization
Initializing an outer circulation variable i to 0, and an inner circulation variable j to 1;
2) control intervention condition determination
The intervention condition of the anti-skid control is that any driving wheel slips or drags the slip phenomenon, namely any one of the following formulas (1) to (4) is involved in the immediate control, and then the step 3) is carried out; if the following conditions are met: omegaLbref(i,j)<ωL(i,j)<ωLref(i, j) and ωRbref(i,j)<ωR(i,j)<ωRref(i, j), the corrected target antiskid control method is finished; the formulae (1) to (4) are as follows:
ωL(i,j)≤ωLbref(i,j) (1)
ωR(i,j)≤ωRbref(i,j) (2)
ωL(i,j)≥ωLref(i,j) (3)
ωR(i,j)≥ωRref(i,j) (4)
wherein the content of the first and second substances,
ωL(i, j) is the left drive wheel speed, ωR(i, j) is the right drive wheel speed;
ωLref(i,j)、ωRref(i, j) are the slip critical speed, omega, of the left and right driving wheels, respectivelyLbref(i,j)、ωRbref(i, j) are the dragging slip critical rotating speeds of the left and right driving wheels under the braking condition, and are calculated according to the following equations (5) to (8):
wherein s isrefIs the critical slip rate of the driving wheel, sbrefThe critical dragging slip rate of the driving wheel; r is the wheel rolling radius; e is a rotation speed amount determined by one order of magnitude less than the minimum rotation speed that can be recognized by the rotation speed sensor; v. ofL(i,j)、vR(i, j) are the wheel center speeds of the left and right driving wheels, respectively, and are calculated according to the equations (9) and (10):
wherein, B2Is the rear track; v (i, j) is the vehicle speed, ωr(i, j) is the yaw rate of the vehicle, and is expressed by the following equations (11) and (12)And (3) calculating:
wherein, ω isL1(i, j) is the left front wheel speed, ωR1(i, j) is the right front wheel speed; thetaSW(i, j) is the steering wheel angle, kSW(i, j) is the steering gear ratio, B1Is the front track;
3) correcting target antiskid control
3.1) calculating a revised control target
At each control step start time, i +1 and j 1 are set, and the correction control target ω of the ith control of the left and right drive wheels is calculated according to equations (13) and (14) respectivelydL(i)、ωdR(i):
Wherein, KeIs a control target correction coefficient, and the value range is (0, 1); omegaL(i-1, N) and ωR(i-1, N) are the rotating speeds of the left and right driving wheels in the Nth control in the i-1 step control respectively; omegaLref(i,1)、ωRref(i, 1) are the slip critical rotation speeds of the left and right driving wheels at the 1 st control in the ith control, omegaLbref(i,1)、ωRbref(i, 1) respectively setting the dragging and sliding critical rotating speeds of the left driving wheel and the right driving wheel in the 1 st control in the ith step;
3.2) calculating wheel control Torque
If the left and right driving wheels simultaneously slip or drag, i.e. if the left driving wheel rotates at a speed omegaLSatisfies the formula (1) or (3) and the right driving wheel rotation speed omegaRSatisfies the formula (2) or formula(4) Then, the calculation of the proportional control torque and the differential control torque of the left and right driving wheels shown in the formulas (15) to (18) in the step 3.2.1) and the step 3.2.2) is carried out;
if only the left driving wheel of the left and right driving wheels slips or drags the left driving wheel to slip, namely the rotating speed omega of the left driving wheelLSatisfies the formula (1) or (3) and simultaneously the right driving wheel rotating speed omegaRSatisfies the following conditions: omegaRbref(i,j)<ωR(i,j)<ωRref(i, j), directly jumping to the step 3.2.3) for calculating the preliminary antiskid torque of the left driving wheel shown in the formula (19);
if only the right driving wheel of the left and right driving wheels slips or drags the right driving wheel to slip, namely the rotating speed omega of the right driving wheelRSatisfies the formula (2) or (4) while the left driving wheel rotation speed omegaLSatisfies the following conditions: omegaLbref(i,j)<ωL(i,j)<ωLref(i, j), directly jumping to the calculation of the preliminary antiskid torque of the right driving wheel shown in the formula (20) in the step 3.2.3);
3.2.1) calculating the proportional control torque:
the control error e of the rotating speed of the left driving wheel in the j control of the i control stepL(i,j)=ωdL(i)-ωL(i, j) right driving wheel rotation speed control error e in j-th control of i-th controlR(i,j)=ωdR(i)-ωR(i, j); and calculating the proportional control torques of the left and right driving wheels according to the formulas (15) and (16):
TPL(i,j)=KPeL(i,j) (15)
TPR(i,j)=KPeL(i,j) (16)
in the formula, KPThe coefficient is an antiskid torque proportionality coefficient, and the coefficient is determined through a calibration experiment;
3.2.2) calculating differential control torque:
calculating differential control torque T of left and right driving wheels according to equations (17) and (18)DL(i,j)、TDR(i,j):
Wherein, KDIs an antiskid torque differential coefficient determined by a calibration experiment;
entering step 3.2.3);
3.2.3) calculating the preliminary anti-skid Torque
Calculating the preliminary antiskid torque T of the left and right driving wheels according to the formulas (19) and (20)SOL(i,j)、TSOR(i,j):
3.2.4) antiskid Torque redistribution
Calculating an antiskid torque redistribution coefficient ρ (i, j) from the vehicle speed:
where ρ (i, j) is the torque redistribution coefficient, vhighAnd vlowRespectively, the highest and lowest vehicle speeds;
calculating the antiskid torque T after the redistribution of the left and the right driving wheels according to the formulas (22) and (23)SL(i,j)、TSR(i,j):
Torque command T finally acting on left and right driving wheelsL(i,j)、TR(i, j) is represented by formulas (24) and (25):
TL(i,j)=TdL(i,j)+TSL(i,j) (24)
TR(i,r)=TdR(i,j)+TSR(i,j) (25)
wherein, TdL(i,j)、TdR(i, j) is a left and right driving wheel driving torque command according to the driver's operation;
4) loop determination
If j is not equal to N, making j equal to j +1, and returning to step 3.2); if j is N, return to step 2).
The invention has the characteristics and beneficial effects that:
the invention relates to an anti-skid control method specially designed for a heavy hub motor vehicle, which can overcome the defects that the response of a motor and a vehicle is delayed more than that of a common passenger vehicle, and the response of the rotating speed of a wheel is slow, and can control the vehicle in a safe running state in a short time when the wheel slips. And the torque is redistributed according to the speed and the slip degree, so that the vehicle has yaw stability when running on roads with poor conditions such as ice and snow curves, split roads and the like, and the sideslip phenomenon is avoided. By the method for correcting the target control, the problem of overshoot of the wheel rotating speed of the large-inertia heavy vehicle caused by integral control is avoided. Meanwhile, due to the introduction of the anti-skid brake, the phenomenon of skidding can be avoided when the vehicle slides at a high speed or runs in a braking mode. Secondly, the invention does not depend on the mass parameters of the vehicle, the total mass and the mass center position of the whole vehicle are greatly changed due to the change of the mass of the goods of heavy vehicles such as passenger cars, trucks and the like because of the change of the number of passengers, and the invention is not influenced by the change of the factors.
Drawings
Fig. 1 is an overall flowchart of a corrected target antiskid control method for a heavy-duty in-wheel motor vehicle according to the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail below with reference to the following embodiments and the accompanying drawings. It should be understood that the detailed description and specific examples, while indicating the scope of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention.
For a better understanding of the present invention, an application example of a modified target anti-skid control method for a heavy-duty in-wheel motor vehicle according to the present invention is described in detail below.
The invention provides a corrected target anti-skid control method for a heavy hub motor vehicle. In the invention, the left and right rear wheels are driving wheels, and the left and right front wheels are driven wheels.
As shown in fig. 1, the control method of the present invention is composed of two nested loops, and in the present invention, control is performed every 0.02s, represented by an internal loop variable j. And N calculations (i.e., when j equals N) are taken as one control step, which is represented by the external loop variable i in the present invention, where N equals 10. In the formula of the invention, (i, j) represents the j control in the ith step of control. j is 1, 2.
Firstly, control is initialized, two cyclic variables i are set to be 0, j is set to be 1, then intervention conditions are judged according to expressions (1) to (4), and anti-skid control is started when any one of expressions (1) to (4) is established, otherwise, the whole control is ended. After the control intervention, the calculation of the corrected control target in the step length is started according to the equations (13) and (14) at each control step length. And repeating the control for N times, wherein each control comprises the steps of calculating proportional torque, calculating differential torque, calculating preliminary antiskid torque, redistributing the antiskid torque and the like, namely calculating according to the formulas (15) to (25), and after each control is finished, making the internal circulation variable j equal to j +1 until j equal to N. After that, the intervention conditions are determined again according to the expressions (1) to (4), and if any condition is satisfied in the same manner, a new step of control is performed by setting i to i +1 and j to 1. The control method comprises the following specific processes:
1) control initialization
The initialized outer loop variable i is 0 and the inner loop variable j is 1.
2) Control intervention condition determination
Anti-skid controlThe intervention condition is that any driving wheel slips or drags the slip phenomenon, namely any one of the following formulas (1) to (4) is used for immediately controlling intervention, and the step 3) is carried out; if the following conditions are met: omegaLbref(i,j)<ωL(i,j)<ωLref(i, j) and ωRbref(i,j)<ωR(i,j)<ωRref(i, j), ending the control method; the formulae (1) to (4) are as follows:
ωL(i,j)≤ωLbref(i,j) (1)
ωR(i,j)≤ωRbref(i,j) (2)
ωL(i,j)≥ωLref(i,j) (3)
ωR(i,j)≥ωRref(i,j) (4)
wherein the content of the first and second substances,
ωL(i, j) is the left drive wheel speed, ωR(i, j) is the rotating speed of the right driving wheel, which is obtained by real-time measurement according to the rotating speed sensors of the left driving wheel and the right driving wheel respectively;
ωLref(i,j)、ωRref(i, j) are the slip critical speed, omega, of the left and right driving wheels, respectivelyLbref(i,j)、ωRbref(i, j) are the dragging slip critical rotating speeds of the left and right driving wheels under the braking condition, and are calculated according to the following expressions (5) to (8):
wherein s isrefIs the critical slip rate of the driving wheel, sbrefBeing driven wheelsCritical dragging slip rate, setting the critical slipping slip rate s of the driving wheel due to the high rigidity of the heavy vehicle tyrerefAnd critical dragging slip ratio sbref10% and-10%, respectively. r is the rolling radius of the wheels, and the rolling radii of the wheels are equal and are the constant parameters of the vehicle. e is a rotating speed quantity determined by one order of magnitude smaller than the minimum rotating speed which can be identified by the rotating speed sensor, the e is introduced to prevent the vehicle from being started, and in the embodiment of the invention, the e is 10-4rad/s。vL(i,j)、vR(i, j) are the wheel center speeds of the left and right driving wheels, respectively, which are calculated according to equations (9) and (10):
wherein, B2Is the rear wheel track, which is a vehicle constant parameter. v (i, j) is the vehicle speed, ωr(i, j) is a vehicle yaw rate, and is calculated according to equations (11) and (12):
wherein, ω isL1(i, j) is the left front wheel speed, ωR1(i, j) is the rotating speed of the right front wheel, which is respectively measured in real time according to the rotating speed sensors of the left driven wheel and the right driven wheel, and thetaSW(i, j) is the steering wheel angle, kSW(i, j) is the steering gear ratio, B1Is the front track; b is1And kSWAre all vehicle parameters.
3) Correcting target antiskid control
The present invention performs antiskid control using proportional-differential control of a correction target. In the following formula, (i, j) represents the j-th control in the i-th step control. j is 1, 2.
3.1) calculating a revised control target
At each control step start time, i is made i +1, j is made 1, and the correction control target in the step is calculated, that is, the correction control target ω of the ith step control of the left and right driving wheels is calculated according to equations (13) and (14) respectivelydL(i)、ωdR(i):
Wherein, KeThe correction coefficient is a control target correction coefficient, the value range is (0, 1), overshoot of control is easily caused when the value approaches 1, and the value is 0.4 in the invention. OmegaL(i-1, N) is the rotation speed of the left drive wheel in the Nth control in the i-1 st control, ωR(i-1, N) is the rotation speed of the right driving wheel in the Nth control in the i-1 st control, ωLref(i,1)、ωRref(i, 1) are the slip critical rotation speeds of the left and right driving wheels at the 1 st control in the ith control, omegaLbref(i,1)、ωRbref(i, 1) are respectively the dragging and sliding critical rotating speeds of the left driving wheel and the right driving wheel in the 1 st control in the ith step of control.
3.2) calculating wheel control Torque
If the left and right driving wheels simultaneously slip or drag, i.e. if the left driving wheel rotates at a speed omegaLThe formula (1) or the formula (3) is satisfied, namely, the left driving wheel slips or drags to slip, and meanwhile, if the rotating speed omega of the right driving wheelRIf the formula (2) or the formula (4) is satisfied, namely the right driving wheel slips or drags the slip phenomenon, calculating the proportional control torque and the differential control torque of the left and right driving wheels shown in the formulas (15) to (18) in the step 3.2.1) and the step 3.2.2);
if only the left driving wheel of the left and right driving wheels slips or drags the left driving wheel to slip, namely the rotating speed omega of the left driving wheelLSatisfies the formula (1) or (3) and simultaneously the right driving wheel rotating speed omegaRSatisfies the following conditions: omegaRbref(i,j)<ωR(i,j)<ωRref(i, j), directly jumping to the step 3.2.3) for calculating the preliminary antiskid torque of the left driving wheel shown in the formula (19);
if only the right driving wheel of the left and right driving wheels slips or drags the right driving wheel to slip, namely the rotating speed omega of the right driving wheelRSatisfies the formula (2) or (4) while the left driving wheel rotation speed omegaLSatisfies the following conditions: omegaLbref(i,j)<ωL(i,j)<ωLref(i, j), directly jumping to the calculation of the preliminary antiskid torque of the right driving wheel shown in the formula (20) in the step 3.2.3).
3.2.1) calculating the proportional control torque:
the control error e of the rotating speed of the left driving wheel in the j control of the i control stepL(i,j)=ωdL(i)-ωL(i, j) right driving wheel rotation speed control error e in j-th control of i-th controlR(i,j)=ωdR(i)-ωR(i, j). The proportional control torque is calculated according to equations (15) and (16):
TPL(i,j)=KPeL(i,j) (15)
TPR(i,j)=KPeL(i,j) (16)
in the formula, TPL(i,j)、TPR(i, j) are the proportional control torques of the j th control of the left and right driving wheels in the i-th step control, respectively, KPIs the antiskid torque proportional coefficient, the coefficient is determined by calibration experiment, K in the embodimentP=650Nm·s。
3.2.2) calculating differential control torque:
calculating differential control torque T of left and right driving wheels according to equations (17) and (18)DL(i,j)、TDR(i,j):
Wherein, TDL(i,j)、TDR(i, j) are differential control torques of j-th control of the left and right drive wheels in the i-th step control, respectively, KDIs the differential coefficient of the antiskid torque, the coefficient is determined by a calibration experiment, in the embodiment, KD=150Nm·s。
Go to step 3.2.3).
3.2.3) calculating the preliminary anti-skid Torque
Preliminary antiskid torque T of left and right driving wheelsSOL(i,j)、TSOR(i, j) is the sum of the proportional control torque and the differential control torque, and is expressed by the formulas (19) and (20):
3.2.4) antiskid Torque redistribution
First, an antiskid torque redistribution coefficient ρ (i, j) is calculated from a vehicle speed:
where ρ (i, j) is the torque redistribution coefficient, vhighAnd vlowThe highest and lowest vehicle speeds, respectively, are taken as 20km/h and 10km/h, respectively, in the embodiment of the present invention, and v (i, j) is the vehicle speed calculated according to equation (11).
Antiskid torque T after redistribution of left and right driving wheelsSL(i,j)、TSR(i, j) is as follows:
the torque command ultimately acting on the drive wheels is as follows:
TL(i,j)=TdL(i,j)+TSL(i,j) (24)
TR(i,j)=TdR(i,j)+TSR(i,j) (25)
wherein, TdL(i,j)、TdR(i, j) is a driving torque command for the left and right driving wheels obtained by the operation of the driver, and the obtaining method is not included in the present invention. T isL(i,j)、TR(i, j) is the torque command of the jth control in the ith step control finally acting on the drive wheels.
4) Loop determination
After equations (15) to (25) are performed, if j ≠ N, then let j ═ j +1, return to step 3.2); if j is N, return to step 2).
Finally, it should be noted that: the above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.
Claims (2)
1. A corrected target anti-slip control method for a heavy hub motor vehicle is characterized by comprising an inner loop and an outer loop, wherein a variable of the inner loop is represented by j, j is 1,2, …, N, N is the maximum number of the inner loop, N inner loops are calculated as a control step length of one outer loop, and (i, j) in the following formula represents the j control in the ith control; the front wheels of the vehicle are all driven wheels, and the rear wheels are all driving wheels; the corrected target antiskid control method comprises the following steps:
1) control initialization
Initializing an outer circulation variable i to 0, and an inner circulation variable j to 1;
2) control intervention condition determination
The intervention condition of the antiskid control is that any driving wheel slips or dragsA slip phenomenon, that is, any one of the following formulas (1) to (4) intervenes in immediate control, and the process proceeds to step 3); if the following conditions are met: omegaLbref(i,j)<ωL(i,j)<ωLref(i, j) and ωRbref(i,j)<ωR(i,j)<ωRref(i, j), the corrected target antiskid control method is finished; the formulae (1) to (4) are as follows:
ωL(i,j)≤ωLbref(i,j) (1)
ωR(i,j)≤ωRbref(i,j) (2)
ωL(i,j)≥ωLref(i,j) (3)
ωR(i,j)≥ωRref(i,j) (4)
wherein the content of the first and second substances,
ωL(i, j) is the left drive wheel speed, ωR(i, j) is the right drive wheel speed;
ωLref(i,j)、ωRref(i, j) are the slip critical speed, omega, of the left and right driving wheels, respectivelyLbref(i,j)、ωRbref(i, j) are the dragging slip critical rotating speeds of the left and right driving wheels under the braking condition, and are calculated according to the following equations (5) to (8):
wherein s isrefIs the critical slip rate of the driving wheel, sbrefThe critical dragging slip rate of the driving wheel; r is the wheel rolling radius; e is in accordance with the ratioThe minimum rotating speed which can be identified by the rotating speed sensor is smaller than a rotating speed amount determined by one order of magnitude; v. ofL(i,j)、vR(i, j) are the wheel center speeds of the left and right driving wheels, respectively, and are calculated according to the equations (9) and (10):
wherein, B2Is the rear track; v (i, j) is the vehicle speed, ωr(i, j) is a vehicle yaw rate, and is calculated according to equations (11) and (12):
wherein, ω isL1(i, j) is the left front wheel speed, ωR1(i, j) is the right front wheel speed; thetaSW(i, j) is the steering wheel angle, kSW(i, j) is the steering gear ratio, B1Is the front track;
3) correcting target antiskid control
3.1) calculating a revised control target
At each control step start time, i +1 and j 1 are set, and the correction control target ω of the ith control of the left and right drive wheels is calculated according to equations (13) and (14) respectivelydL(i)、ωdR(i):
Wherein, KeIs a control target correction coefficient, and the value range is (0, 1); omegaL(i-1, N) and ωR(i-1, N) are the rotating speeds of the left and right driving wheels in the Nth control in the i-1 step control respectively; omegaLjef(i,1)、ωRref(i, 1) are the slip critical rotation speeds of the left and right driving wheels at the 1 st control in the ith control, omegaLbref(i,1)、ωRbref(i, 1) respectively setting the dragging and sliding critical rotating speeds of the left driving wheel and the right driving wheel in the 1 st control in the ith step;
3.2) calculating wheel control Torque
If the left and right driving wheels simultaneously slip or drag, i.e. if the left driving wheel rotates at a speed omegaLSatisfies the formula (1) or (3) and the right driving wheel rotation speed omegaRIf the formula (2) or the formula (4) is satisfied, the proportional control torque and the differential control torque of the left and right driving wheels shown in the formulas (15) to (18) in the step 3.2.1) and the step 3.2.2) are calculated;
if only the left driving wheel of the left and right driving wheels slips or drags the left driving wheel to slip, namely the rotating speed omega of the left driving wheelLSatisfies the formula (1) or (3) and simultaneously the right driving wheel rotating speed omegaRSatisfies the following conditions: omegaRbref(i,j)<ωR(i,j)<ωRref(i, j), directly jumping to the step 3.2.3) for calculating the preliminary antiskid torque of the left driving wheel shown in the formula (19);
if only the right driving wheel of the left and right driving wheels slips or drags the right driving wheel to slip, namely the rotating speed omega of the right driving wheelRSatisfies the formula (2) or (4) while the left driving wheel rotation speed omegaLSatisfies the following conditions: omegaLbref(i,j)<ωL(i,j)<ωLref(i, j), directly jumping to the calculation of the preliminary antiskid torque of the right driving wheel shown in the formula (20) in the step 3.2.3);
3.2.1) calculating the proportional control torque:
the control error e of the rotating speed of the left driving wheel in the j control of the i control stepL(i,j)=ωdL(i)-ωL(i, j) right driving wheel rotation speed control error e in j-th control of i-th controlR(i,j)=ωdR(i)-ωR(i, j); calculating the left,Proportional control torque of right drive wheel:
TPL(i,j)=KPeL(i,j) (15)
TPR(i,j)=KPeL(i,j) (16)
in the formula, KPThe coefficient is an antiskid torque proportionality coefficient, and the coefficient is determined through a calibration experiment;
3.2.2) calculating differential control torque:
calculating differential control torque T of left and right driving wheels according to equations (17) and (18)DL(i,j)、TDR(i,j):
Wherein, KDIs an antiskid torque differential coefficient determined by a calibration experiment;
entering step 3.2.3);
3.2.3) calculating the preliminary anti-skid Torque
Calculating the preliminary antiskid torque T of the left and right driving wheels according to the formulas (19) and (20)SOL(i,j)、TSOR(i,j):
3.2.4) antiskid Torque redistribution
Calculating an antiskid torque redistribution coefficient ρ (i, j) from the vehicle speed:
where ρ (i, j) is twistMoment redistribution coefficient, vhighAnd vlowRespectively, the highest and lowest vehicle speeds;
calculating the antiskid torque T after the redistribution of the left and the right driving wheels according to the formulas (22) and (23)SL(i,j)、TSR(i,j):
Torque command T finally acting on left and right driving wheelsL(i,j)、TR(i, j) is represented by formulas (24) and (25):
TL(i,j)=TdL(i,j)+TSL(i,j) (24)
TR(i,j)=TdR(i,j)+TSR(i,j) (25)
wherein, TdL(i,j)、TdR(i, j) is a left and right driving wheel driving torque command according to the driver's operation;
4) loop determination
If j is not equal to N, making j equal to j +1, and returning to step 3.2); if j is N, return to step 2).
2. The corrected target antiskid control method according to claim 1, wherein in step 2), the critical slip-slip ratio s of the drive wheel is setrefAnd critical dragging slip ratio sbref10% and-10%, respectively.
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US5813487A (en) * | 1994-09-02 | 1998-09-29 | Gottlob Auwarter Gmbh & Co. | Omnibus |
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CN107512262A (en) * | 2017-08-14 | 2017-12-26 | 吉林大学 | A kind of vehicle stability control system tire force distribution method for performing during driving limited space |
CN108313062A (en) * | 2018-01-25 | 2018-07-24 | 中国第汽车股份有限公司 | A kind of the torque distribution control method and system of distributed driving electric vehicle |
CN108482379A (en) * | 2018-03-16 | 2018-09-04 | 武汉理工大学 | Wheel-hub motor driven vehicle coefficient of road adhesion and road gradient synchronize real-time estimation system and method |
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US5813487A (en) * | 1994-09-02 | 1998-09-29 | Gottlob Auwarter Gmbh & Co. | Omnibus |
JP2000516703A (en) * | 1996-06-13 | 2000-12-12 | アイティーティー・マニュファクチャリング・エンタープライジズ・インコーポレーテッド | Method for controlling the driving state of a car |
CN107512262A (en) * | 2017-08-14 | 2017-12-26 | 吉林大学 | A kind of vehicle stability control system tire force distribution method for performing during driving limited space |
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