JP3940569B2 - Anti-skid control device - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to an anti-skid control device that prevents wheel locking by increasing / decreasing the hydraulic pressure during braking of a wheel cylinder provided on each wheel in a vehicle, and in particular, a traveling road surface is reduced during anti-skid control. Friction coefficient (low μ)The present invention relates to a technique for improving a μ jump determination method for determining that a friction coefficient (hereinafter referred to as μ) has changed (jumped) to a high friction coefficient (high μ).
[0002]
[Prior art]
As a method for determining a μ jump in a conventional anti-skid control device, for example, a method described in JP-A-8-216862 is known. In this conventional μ jump determination method, the running road surface has a low friction coefficient (low μ) based on the detected value of the number of times of slow increase of the working fluid during anti-skid control detected by the number of times of pressure increase detection means.)That is, a change (jump) from a high friction coefficient (high μ) is determined, that is, a μ jump is determined. In addition, it is also known that the μ jump is determined based on the slow pressure increasing time or the length of time that the slip is shallow.
[0003]
[Problems to be solved by the invention]
However, in the conventional μ jump detection device, as described above, the μ jump determination is performed based on the number of times of slow pressure increase corresponding to the length of the slow pressure increase time or the length of time that the slip is shallow. As a result, there were the following problems.
That is, as shown in the time chart of FIG. 12, when the road surface μ gradually changes from a low μ road to a high μ road, for example, in the case of gradually changing from a gravel road to a paved road, Since the number of times of slow pressure increase and the time during which the slip is in a shallow state are shortened, there is a possibility that the μ jump judgment cannot be made despite the fact that there is a μ jump from the low μ road to the high μ road. In this case, although the actual vehicle speed (dotted line) is decelerating, the process at the time of μ jump determination, that is, the process of updating the value of the vehicle deceleration to a high value for the high μ road is not performed. Since the pseudo vehicle speed is obtained based on the low vehicle deceleration for the low μ road, the pseudo vehicle speed becomes higher than the actual vehicle speed. As a result, the pseudo vehicle speed is set based on the pseudo vehicle speed. Set the decompression judgment threshold (control target speed) to a high value. Is, thereby, become excessive vacuum state, the vehicle deceleration can not be obtained.
[0004]
The present invention has been made paying attention to the above-mentioned conventional problems, and even when the road surface μ gradually changes from a low μ road to a high μ road, μ jump determination can be reliably performed. Accordingly, it is an object of the present invention to provide an anti-skid control device that can avoid the occurrence of a vehicle body deceleration insufficiency state due to the occurrence of an over-depressurized state.
[0005]
[Means for Solving the Problems]
In order to achieve the above object, in the anti-skid control device according to claim 1 of the present invention, a master cylinder for generating a brake fluid pressure and each wheel in the vehicle are respectively provided and controlled by a fluid pressure supply. Switching between a brake cylinder for generating power, a pressure reduction control state for reducing the hydraulic pressure of the brake cylinder, a holding control state for holding the hydraulic pressure, and a pressure increase control state for increasing the hydraulic pressure Switching control means capable of driving control, wheel speed detection means for detecting the wheel speed of each wheel,A wheel acceleration calculating means for calculating the acceleration of each wheel from the wheel speed detected by the wheel speed detecting means, a vehicle body deceleration estimating means for estimating the vehicle body deceleration, and a pseudo vehicle body speed calculated in the previous control cycle. When the previous value of the pseudo vehicle speed is equal to or higher than the maximum wheel speed among the wheel speeds detected by the wheel speed detection means, the pseudo vehicle speed is determined according to the vehicle deceleration estimated by the vehicle body deceleration estimation means. The pseudo vehicle speed in the current control cycle is calculated by reducing the previous vehicle speed value. On the other hand, if the previous pseudo vehicle speed value is smaller than the maximum wheel speed, a predetermined speed is added to the previous pseudo vehicle speed value. And calculate the simulated vehicle speed this timePseudo vehicle speed calculation means, control target speed calculation means for calculating a wheel control target speed in consideration of a predetermined slip ratio from the pseudo vehicle speed calculated by the pseudo vehicle speed calculation means;,When the wheel speed detected by the wheel speed detection means becomes the control target speed calculated by the control target speed calculation means, the switching control means is switched to the pressure reduction control state to reduce the hydraulic pressure of the brake cylinder. The wheel acceleration calculated by the wheel acceleration calculating means is then executed.Based onBrake hydraulic pressure control means for executing pressure increase control for increasing the hydraulic pressure of the brake cylinder by switching the switching control means to the pressure increase control state;The pseudo vehicle speedStorage means for storingThe vehicle body deceleration estimation means comprises the maximum vehicleWheel speed is beforeImitationSimilar vehicle speedSwitched from a larger state to a state below the simulated vehicle speed.The vehicle body speed at the time of spin-up is obtained as the vehicle speed at the time of spin-up, and the vehicle speed at the time of spin-up and the decompression control start time stored in the storage means are calculated.The pseudo vehicle speedEstimate vehicle deceleration from the differential value ofShi,For the wheel whose wheel speed detected by the wheel speed detecting means is the maximum among the wheels,in frontCarCalculated by wheel acceleration calculation meansCarWheel acceleration isFrom a state greater than zeroBelow zeroSwitched to the state ofof timeWheelEach wheel that calculates the vehicle speed at the time of spin-up for each wheel and estimates the vehicle deceleration for each wheel from the differential value of the vehicle speed at the time of spin-up last time and the vehicle speed at the time of each wheel spin-up Vehicle body deceleration estimation means, vehicle body deceleration estimated by the vehicle body deceleration estimation means, and vehicle body deceleration for each wheel estimated by the vehicle body deceleration estimation meansDegree andMu jump determination means for determining that the traveling road surface has changed from the low friction coefficient road to the high friction coefficient road when the difference between the two is greater than a predetermined value, and the traveling road surface from the low friction coefficient road to the high friction coefficient road by the mu jump determination means When it is determined that the change has occurred, a correction means during mu jump for subtracting and correcting the control target speed by a predetermined value;Is providedIt was a means.
[0006]
The anti-skid control device according to claim 2 is the anti-skid control device according to claim 1, wherein the vehicle body deceleration estimation means includesBeforeBody speed at the time of spin-upWhen is requestedAnd body speed at the time of this spin-upWhen is requestedInterval time withIs the wheel speed spin up interval timeA spin-up interval measuring means for measuring the vehicle body deceleration, and the mu-jump determining means for the vehicle body deceleration estimated by the vehicle body deceleration estimating means and the vehicle body deceleration for each wheel estimated by the vehicle body deceleration estimating means for each wheel.Degree andThe difference betweenCarMeans are configured to determine that the traveling road surface has changed from the low friction coefficient road to the high friction coefficient road when the wheel speed spin-up interval time becomes a predetermined value or more.
[0007]
4. The anti-skid control device according to claim 3, wherein the mu jump determination means includes a vehicle body deceleration estimated by the vehicle body deceleration estimation means and a vehicle body deceleration for each wheel. Vehicle deceleration for each wheel estimated by the estimation meansDegree andWhen the vehicle difference estimated by the vehicle body deceleration estimation means is less than a predetermined value, it is determined that the traveling road surface has changed from the low friction coefficient road to the high friction coefficient road. It was set as the means comprised as follows.
[0008]
[Action]
Since the anti-skid control device according to the first aspect of the present invention is configured as described above, the braking fluid pressure control means uses the wheel speed.Every timeWhen the wheel speed of each wheel detected by the detection means reaches a predetermined control target speed obtained from the vehicle speed calculated by the pseudo vehicle speed calculation means, the switching control means is switched to the decompression control state for braking. The pressure reduction control for reducing the hydraulic pressure in the cylinder is performed, thereby reducing the braking force and preventing the wheels from being locked. After that, the wheel is reduced by executing the decompression control as described above.AdditionWheel calculated by speed calculation meansAdditionWhen the speed becomes zero or less or the wheel acceleration exceeds a certain value, the switching control means is switched to the pressure increasing control state to execute the pressure increasing control for increasing the hydraulic pressure of the brake cylinder, thereby increasing the braking force. To prevent the occurrence of insufficient deceleration of the vehicle body.
[0009]
Also, the vehicle body deceleration estimating means is the vehicle speed at the time of spin-up and the decompression control start time stored in the storage means.Fake body speedThe vehicle body deceleration is estimated from the differential value ofFor the wheel with the highest wheel speed of each wheel,Wheel acceleration isFrom a state greater than zeroBelow zeroSwitched to the state ofof timeWheelThe speed is obtained as the vehicle speed at the time of spinning up for each wheel, and the vehicle body deceleration at each wheel is estimated from the differential value between the vehicle speed at the time of spinning up for each wheel and the speed of the vehicle at the time of spinning up for each wheel. In the mu jump determination means, the vehicle body deceleration and the vehicle body deceleration for each wheel are performed.Degree andWhen the difference between the two is greater than the predetermined value, the road surface has changed from a low friction coefficient road to a high friction coefficient road (mu-This jump)-When the jump determination is made, the mu jump correction means performs a process of subtracting and correcting the control target speed by a predetermined value. With this control target speed subtraction correction process, the brake cylinder hydraulic pressure is controlled in accordance with the actual vehicle speed that is decelerated by the shift to the high friction coefficient road. As described above, vehicle deceleration and vehicle deceleration for each wheelDegree andBy making the judgment based on the difference between the low μ road and the high μ road, even when the road surface μ gradually changes, the mu-Jump judgment can be made.
[0010]
In the anti-skid control device according to claim 2, as described above, as the mu jump determination condition, the vehicle body deceleration estimated by the vehicle body deceleration estimating means and the vehicle body deceleration estimating means for each wheel are estimated. Wheel-by-wheel decelerationDegree andIn addition to that the difference between the two is not less than a predetermined value, the fact that the wheel speed spin-up interval time measured by the spin-up interval measuring means is not less than a predetermined value is added.-The jump determination accuracy can be further increased.
[0011]
4. The anti-skid control device according to claim 3, wherein as the mu jump determination condition, the vehicle body deceleration estimated by the vehicle body deceleration estimating means and the vehicle deceleration for each wheel estimated by the vehicle body deceleration estimating means.Degree andWhen the vehicle body deceleration estimated by the vehicle body deceleration estimating means is not more than a predetermined value, that is, when the low friction coefficient road determination is made, By adding the condition-The jump determination accuracy can be further increased.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. First, the configuration of the anti-skid control device according to the embodiment of the present invention will be described with reference to the system outline diagram of FIG. 1. The vehicle includes rotations of the right front wheel 10 and the left front wheel 14 that are steering wheels (driven wheels). Wheel speed sensors (wheel speed detecting means) 12 and 16 that generate wheel speed pulses in response to the wheel, and wheels that generate wheel speed pulses in response to the rotation of the right rear wheel 20 and the left rear wheel 22 that are drive wheels, respectively. Speed sensors (wheel speed detecting means) 24 and 26 are provided, and these sensors are connected to a control unit (hereinafter referred to as ECU) 40 including a microcomputer (CPU).
[0013]
In addition, as shown in the brake hydraulic pressure circuit configuration diagram (only one wheel) in FIG. 2, the wheel cylinder (braking cylinder) 50 disposed on each wheel and the brake fluid when the driver steps on the brake pedal. The master cylinder 52 that generates pressure is communicated with a main fluid passage 54, and an actuator unit 60 that controls the fluid pressure of each wheel cylinder 50 is interposed in the middle of the main fluid passage 54. In FIG. 2, illustration is omitted and only one brake hydraulic circuit and one wheel are illustrated, but the master cylinder 52The two brake hydraulic circuits are connected to one of them, and the wheel cylinders 50 and 50 of the right front wheel 10 and the left rear wheel 22 are connected to one brake hydraulic circuit, and the other brake hydraulic circuit is connected to the other brake hydraulic circuit. The wheel cylinders 50 and 50 of the left front wheel 14 and the right rear wheel 20 are connected.
[0014]
The actuator unit 60 includes a switching control valve (switching control means) 62 for switching control of increase / decrease of the hydraulic pressure of each wheel cylinder 50, and a reservoir 64 for storing the brake fluid when the wheel cylinder 50 is depressurized. And a hydraulic pump 66 for returning the brake fluid stored in the reservoir 64 to the main fluid passage 54. The reservoir 64 is provided in each of the two brake fluid pressure circuits.
[0015]
Next, the basic control content of the anti-skid control in the ECU 40 will be described based on the control flowchart of FIG.
First, in step S1, calculation of the respective wheel speeds VW of the right front wheel 10, the left front wheel 14, the right rear wheel 20 and the left rear wheel 22 according to the outputs from the wheel speed sensors 12, 16, 24, 26, and The wheel acceleration VWD is calculated by differentiating each wheel speed VW.
[0016]
In the following step S2, a pseudo vehicle speed, that is, a pseudo vehicle body speed VI is calculated from each wheel speed VW calculated in step S1. The details of the calculation of the pseudo vehicle speed VI will be described in detail later based on the flowcharts of FIGS.
[0017]
In the subsequent step S3, the control target speed (decompression judgment threshold value) VWS is calculated from the pseudo vehicle speed VI calculated in step S2. The calculation contents of the control target speed VWS will be described in detail later based on the flowchart of FIG.
[0018]
In the subsequent step S4, PI control calculation processing is performed. That is, the target pressure increase / reduction pulse time PB indicating the target brake fluid pressure increase / reduction control time is calculated. The contents of this PI control calculation process will be described in detail later based on the flowchart of FIG.
[0019]
In subsequent step S5, the wheel speed VW of each wheel calculated in step S1 is determined., SuIt is determined whether it is less than the control target speed VWS calculated in step S3 and the pressure increase execution flag ZFLAG (flag indicating that pressure increase control is being executed) is set to 1, YES (VW When <VWS and ZFLAG = 1), it is necessary to execute pressure reduction control, and the process proceeds to step S7.
[0020]
In this step S7, after performing the process enumerated below, it progresses to step S8 which implements brake fluid pressure reduction control.
・ Set decompression control execution time AS to a predetermined time A.
・ Reset holding control time THOJI to 0.
・ Set decompression execution flag GFLAG to 1.
[0021]
In step S8, brake fluid pressure reduction control is performed. That is, a switching signal is output from the ECU 40 to the switching control valve 62 of the actuator unit 60, and the master cylinder 52, the wheel cylinder 50, and the reservoir 64 are communicated.
[0022]
When the determination in step S5 is NO (VW ≧ VWS or ZFLAG = 0), the process proceeds to step S6. This step S6 is a step of determining the necessity of the brake hydraulic pressure reduction control. Specifically, the holding control time THOJI exceeds the predetermined time Bms, and the target increase / decompression pulse time PB-depressurization time timer DECT is set. Predetermined time T₁ ms (T1 <) is exceeded, or the holding control time THOJI exceeds the predetermined time Cms (B <C), and the time obtained by subtracting the decompression time timer DECT from the target increase / decrease pulse time PB is the predetermined time. It is determined whether or not T2ms (T2 <T1) has been exceeded. If YES (either one of the conditions is met), the pressure reduction control needs to be performed, and thus the process proceeds to step S7.
[0023]
Further, when the determination in step S6 is NO (both conditions are not satisfied), the process proceeds to step S9 to determine the necessity of the brake fluid pressure increasing or holding control, and the brake fluid pressure increasing control is necessary. Determine sex. Specifically, target increase / decrease pulse time PBInIncrease pressure timer INCTAdditionThe calculated time is the predetermined time -T ₂  It is determined whether it is less than ms and the holding control time THOJI exceeds Cms. When the determination in step S9 is YES (both conditions are met), it can be determined that the wheel has not slipped yet, so the process proceeds to step S10.
[0024]
In step S10, it is further determined whether or not the pressure reduction execution flag GFLAG (a flag indicating that pressure reduction control is being performed) is set to 1 and the wheel acceleration VWD exceeds 0 g, and NO ( When at least one of the conditions is not satisfied), the hydraulic pressure of the wheel cylinder 50 is insufficient. Therefore, the process proceeds to step S11 and the holding control time THOJI is reset to 0, and then the brake hydraulic pressure increase control is performed. Proceed to Step S12.
[0025]
In step S12, brake fluid pressure increase control is performed. That is, in this case, the switching control valve 62 of the actuator unit 60 is driven so that the master cylinder 52 and the wheel cylinder 50 are in communication with each other. In step S13, the pressure increasing execution flag ZFLAG is set to 1.
[0026]
Further, the determination in step S9 is NO (PB+ INCTBut≧-T ₂  ms or THOJI ≦ Cms) or YES in step S10 (GFLAG =1,And, VWD> 0), The process proceeds to step S14 to increment the holding control time THOJI, and then proceeds to step S15 for executing the brake hydraulic pressure holding control.
[0027]
In step S15, brake fluid pressure holding control is performed. That is, in this case, the switching control valve 62 is driven to a position where the wheel cylinder 50 cuts off the communication between the master cylinder 52 and the reservoir 64.
[0028]
After any one of the steps S8, S13, S15 is performed, the process proceeds to step S16, where it is determined whether 10 ms has elapsed or not. If less than 10 ms (NO), the determination of step S16 is repeated. If 10 ms has elapsed (YES), the process proceeds to step S17. In other words, the control routine is executed every 10 ms.
[0029]
In subsequent step S17, after decrementing the decompression control execution time AS,
This completes one flow and returns to step S1.
[0030]
Next, the specific contents of the pseudo vehicle speed calculation processing control in step S2 in FIG. 3 will be described based on the flowchart of FIG.
First, in step S21, after setting the maximum value of the wheel speed VW of the four wheels as the select high wheel speed VFS, the process proceeds to step S22.
[0031]
In this step S22, it is determined whether or not the non-decompression control is being performed based on whether or not the depressurization control execution time AS is 0. If YES (AS = 0, the non-decompression control is being performed), step S23 is performed. After the maximum value of the wheel speed VW of the driven wheel is set as the select high wheel speed VFS, the process proceeds to step S24. If NO (AS ≠ 0 and pressure reduction control is being performed), the process directly proceeds to step S24. move on.
[0032]
In this step S24, it is determined whether or not the pseudo vehicle speed VI is equal to or higher than the select high wheel speed VFS. If YES (VI ≧ VFS), the process proceeds to step S25.WheelAfter obtaining the pseudo vehicle speed VI at the time of deceleration by the following equation, one flow is finished.
VI = VI-VIK × k
Note that VIK is a vehicle body deceleration. The calculation content of the vehicle body deceleration VIK will be described in detail later based on the flowchart of FIG.
[0033]
When NO (VI <VFS) in step S24,WheelIs determined to be accelerating, the process proceeds to step S26, the deceleration limiter constant x is set to 2 km / h, and then the process proceeds to step S27..In this step S27, it is determined whether or not the non-decompression control is being performed again based on whether or not the depressurization control execution time AS is 0. If YES (AS = 0, non-decompression control is being performed), The process proceeds to S28, the deceleration limiter constant x is set to 0.1 km / h, and then the process proceeds to step S29. If NO (AS ≠ 0 and the pressure reduction control is being performed), the process proceeds to step S29 as it is.
[0034]
In step S29, the pseudo vehicle speed VI is obtained by the following equation, and one flow is completed.
VI = VI + x
[0035]
Next, the specific contents of the vehicle deceleration calculation used in step S25 of FIG. 4 will be described based on the flowchart of FIG.
First, in step S251, it is determined whether or not the non-depressurization control (AS = 0) is switched to the depressurization control (AS ≠ 0). If YES, the process proceeds to step S252 to perform the depressurization control. Is set to the pseudo vehicle speed VI and the vehicle deceleration creation timer TO is reset to 0, the process proceeds to step S253, and NO (non- When the pressure reduction control is being performed (AS = 0)), the process proceeds to step S253 as it is. In step S253, the wheel speed spin-up interval time VPT is incremented and the vehicle deceleration creation timer TO is incremented, and then the process proceeds to step S254.
[0036]
In step S254 (spin-up determination), it is determined whether or not the select high wheel speed VFS has returned to the pseudo vehicle speed VI. If YES (VI <VFS → VI ≧ VFS), the process proceeds to step S255. The vehicle body deceleration VIK is obtained by the following formula,
VIK = (VO-VI) / TO
Further, the process proceeds to step S256, the wheel speed spin-up interval time VPT is reset to 0, and then the process proceeds to step S257.
[0037]
If the determination in step S254 is NO (VI <VFS), the process proceeds directly to step S257. In this step S257 (low μ road determination), it is determined whether or not the road surface is a low μ road by determining whether or not the decompression time timer DECT is equal to or greater than Dms, and YES (DECT ≧ Dms = If it is a low μ road), the process proceeds to step S258, and the low μ flag LoμAfter setting F to 1, the process proceeds to step S259. If NO (DECT <Dms = high μ road), the process proceeds to step S259 as it is.
[0038]
In step S259, after the μ jump determination is made, one flow is finished. The contents of the μ jump determination will be described in detail later based on the flowchart of FIG.
[0039]
Next, the specific contents of the control target speed calculation of step S3 in FIG. 3 will be described based on the flowchart of FIG.
First, in step S31, the offset value XX of the control target speed VWS is first set to 8 km / h, and then the process proceeds to step S32.
[0040]
In step S32, the vehicle body deceleration is less than a predetermined value E.Ruka,Or, Low μ flag LoμBy determining whether or not F is set to 1, it is determined whether or not the traveling road surface is a low μ road. If YES (low μ road determination), the process proceeds to step S33, and the offset After changing and setting the value XX to 4 km / h, the process proceeds to step S34. If NO (high μ road determination), the process proceeds to step S34 as it is (with XX = 8 km / h set).
[0041]
In step S34, the control target speed VWS is calculated based on the following expression from the pseudo vehicle speed VI calculated in the flow of FIG. 4 and the offset value XX, and then the process proceeds to step S35.
VWS = 0.95 × VI-XX
[0042]
In this step S35, it is determined whether or not the decompression flag GFLAG is set to 1, the wheel acceleration VWD exceeds the predetermined value F, and the wheel speed VW exceeds the control target speed VWS. Advances to step S36 to set the target slip vehicle speed VWM to the pseudo vehicle speed VI, and when NO, advances to step S37 to set the target slip vehicle speed VWM to the control target speed VWS. End the flow of times.
[0043]
Next, the specific contents of the PI control calculation process of step S4 in FIG. 3 will be described based on the flowchart of FIG.
First, in step S41, a deviation ΔVW is obtained based on the following equation.
ΔVW = VWM-VW
[0044]
In the subsequent step S42, the proportional component PP of the PI control is obtained by the following equation.
PP = KP × ΔVW
[0045]
In the subsequent step S43, an integral part IP of PI control is obtained by the following equation.
IP = 10ms before IP + KI × ΔVW
Note that KI is a coefficient.
[0046]
In the subsequent step S44, the target increase / decrease pulse time PB is obtained by the following equation, and one flow is completed.
PB = PP + IP
[0047]
Next, the specific contents of the pressure reduction control in step S8 in FIG. 3 will be described based on the flowchart in FIG.
First, in step S121, the pressure increase time counter INCT is reset to 0, and in step S122, the decompression pulse time GAW is set to the target increase / decrease pulse time PB, and then the process proceeds to step S123.
[0048]
In this step S123, it is determined whether or not the pressure increasing execution flag ZFLAG is set to 1. If YES (ZFLAG = 1), the process proceeds to step S124, and the pressure reducing pulse time GAW is obtained by the following equation. ,
GAW = VWD × α / VIK (α: coefficient)
After resetting the pressure increasing execution flag ZFLAG to 0, the process proceeds to step S125. When NO (ZFLAG = 0), the process proceeds to step S125 as it is.
[0049]
In step S125, the port decompression output process is performed and the decompression time timer DECT is incremented, and then the process proceeds to step S126.
[0050]
In this step S126, it is determined whether the decompression time timer DECT is equal to or greater than the decompression pulse time GAW or whether the wheel acceleration VWD exceeds a predetermined value F, and YES (DECT ≧ GAW, or, VWD> F). If YES, the process proceeds to step S127 to perform the holding control output process and decrement the decompression time timer DECT. Then, one flow is finished, and NO (DECT <GAW, and, VWD ≦ When it is F), one flow is finished as it is.
[0051]
Next, the specific content of the pressure increase control in step S12 in FIG. 3 will be described based on the flowchart in FIG.
First, in step S151, the decompression time counter DECT is reset to 0. In subsequent step S152, the pressure increase pulse time ZAW is set to the target pressure increase / reduction pulse time PB, and then the process proceeds to step S153.
[0052]
In a succeeding step S153, it is determined whether or not the decompression execution flag GFLAG is set to 1. When YES (GFLAG = 1), the process proceeds to a step S154.IncreasePressure pulse timeZAW is obtained by the following equation, andZAW = VWD × β × VIK (β: coefficient)
After resetting the decompression execution flag GFLAG to 0, the process proceeds to step S155. If NO (GFLAG = 0), the process proceeds to step S155 as it is.
[0053]
In step S155, the port pressure increasing output process is performed and the pressure increasing time timer INCT is incremented, and then the process proceeds to step S156.
[0054]
In step S156, it is determined whether or not the pressure increase time timer INCT is equal to or greater than the pressure increase pulse time ZAW. If YES (INCT ≧ ZAW), the process proceeds to step S157 to perform port holding output processing. After decrementing the pressure increase time timer INCT, one flow is finished. When NO (INCT <ZAW), one flow is finished as it is.
[0055]
Next, specific contents of the μ jump determination in step S259 in FIG. 5 will be described based on the flowchart of FIG.
First, in step S90, the select high wheel speed VFS which is the maximum value of the wheel speed VW of each of the wheels 10, 14, 20, 22 is obtained, and in step S91, the select high wheel acceleration VWDSH is obtained by the following equation:
VWDSH = (VFS-VFS 10m before) / 10ms
In the following step S92, the wheel speed spin-up interval time VPTSH is incremented.
[0056]
In the following step S93, the spin-up state of the select high wheel acceleration VWDSH is determined by determining whether or not the select high wheel acceleration VWDSH has decreased from 0 g to 0 g or less, and YES (spin up occurrence) is determined. In some cases, the process proceeds to step S94, and each wheel body deceleration estimated value EVIK is obtained by the following equation.
EVIK = (VWSH0−VWSH) / VPTSH
Then, in preparation for the next calculation of each wheel body deceleration estimated value EVIK, in step S95, the previous reference spin-up point wheel speed VWSH0 is updated to the current spin-up point wheel speed VWSH. In step S96, the wheel speed spin-up interval time VPTSH is reset to 0, and then the process proceeds to step S97.
If the determination in step S93 is NO (no spin-up has occurred), the process proceeds directly to step S97.
[0057]
In step S97, it is determined whether or not the wheel speed spin-up interval time VPT used for obtaining the vehicle body deceleration VIK with reference to the pseudo vehicle body speed VI is 600 ms or more. If YES (VPT ≧ 600 ms), Since there is a possibility of μ jump, the process proceeds to step S98. If NO (VPT <600 ms), it is determined that no μ jump has occurred, and thus one flow is completed.
[0058]
In step S98, the low μ road determination is made by determining whether or not the vehicle body deceleration VIK is less than 0.4 g.AhIf YES (VIK <0.4 g), there is a possibility of μ jump, so the process proceeds to step S99. If NO (VIK ≧ 0.4 g), the wheel speed is determined. Even if the spin-up interval time VPT is 600 ms or longer, it is determined that no μ jump has occurred, and thus one flow is completed.
[0059]
In step S99, it is determined whether or not the value obtained by subtracting the vehicle body deceleration VIK from each wheel vehicle body deceleration estimated value EVIK exceeds 0.3 g. If YES (EVIK−VIK> 0.3 g), μ is determined. Since it is determined that a jump has occurred, the process proceeds to step S100, the spin-up point wheel speed VWSH is set to the pseudo vehicle speed VI at that time, the wheel speed spin-up interval time VPT is reset to 0, and the vehicle deceleration VIK is set. After setting the initial setting value 1.3 g for the high μ road, this completes one flow. When the determination in step S99 is NO (EVIK−VIK ≦ 0.3 g), even if the wheel speed spin-up interval time VPT is 600 ms or more and the vehicle body deceleration VIK is less than 0.4 g. Since it is determined that no μ jump has occurred, this completes one flow.
[0060]
Next, the operation and effect of the embodiment of the present invention will be described based on the time chart of FIG.
(B) Anti-skid basic control
Since the anti-skid control device according to the embodiment of the present invention is configured as described above, the ECU 40 detects the wheels of the wheels 10, 14, 20, and 21 detected by the wheel speed sensors 12, 16, 24, and 26. When the speed VW becomes less than the control target speed VWS obtained from the simulated vehicle body speed VI, the wheels may be locked. Therefore, the pressure reduction for reducing the hydraulic pressure of the wheel cylinder 50 by switching the switching control valve 62 to the pressure reduction control state. Reduce the braking force by executing the control. By executing the pressure reduction control, the wheel speed VW is changed from the deceleration direction to the acceleration direction, and the wheels are prevented from locking.
[0061]
Thereafter, when the wheel acceleration VWD becomes zero or less by executing the pressure reduction control as described above, the switching control valve 62 is switched to the pressure increase control state, and the pressure increase control for increasing the hydraulic pressure of the wheel cylinder 50 is executed. Strengthen the power to prevent the occurrence of insufficient deceleration of the vehicle body.
[0062]
(B) During μ jump
During the anti-skid control as described above, as shown in the time chart of FIG. 11, when the traveling road surface shifts from the low μ road to the high μ road, the longitudinal acceleration value indicating the actual vehicle deceleration increases. The vehicle body deceleration estimated value EVIK for each wheel is updated in the direction of increasing due to the decrease in the wheel slip ratio, whereas the value of the vehicle body deceleration VIK is not updated.
[0063]
That is, the vehicle body deceleration VIK determines the spin-up state of the selected high wheel speed VFS based on whether the selected high wheel speed VFS has returned to the pseudo vehicle body speed VI (VI <VFS → VI ≧ VFS) (step S254). Then, it is obtained (updated) by differentiating the pseudo vehicle speed VI at the time of spin-up and the vehicle speed VO at the start of pressure reduction control at the point of connection (step S25).5Therefore, the transition from the low μ road to the high μ road causes the select high wheel speed VFS to decrease as the actual vehicle speed decreases, while the value of the pseudo vehicle speed VI is still updated. Therefore, the spin-up state of the select high wheel speed VFS based on the return to the pseudo vehicle body speed VI is not formed as described above, and therefore the value of the vehicle body deceleration VIK is updated. There is no.
[0064]
On the other hand, each wheel body deceleration estimated value EVIK determines the spin-up state of the selected high wheel acceleration VWDSH based on whether or not the selected high wheel acceleration VWDSH has decreased from 0 g to 0 g or less (step S93). Since the selection high wheel acceleration VWDSH at the time of spin up is obtained by differentiation (step S94), a spin-up state is always generated, and each wheel vehicle body is shifted from the low μ road to the high μ road. The deceleration estimated value EVIK is updated so as to increase.
[0065]
Therefore, by determining whether or not the difference between the vehicle body deceleration VIK and each wheel vehicle body deceleration estimated value EVIK is a predetermined value (0.3 g) or more (step S99), the traveling road surface is increased from the low μ road to the high road surface. When it is determined that the road has changed to the μ road (μ jump), and when the μ jump determination is made, the vehicle deceleration VIK value is updated to the initial setting value 1.3 g for the high μ road (step) S100) is performed.
[0066]
Then, by updating the vehicle body deceleration VIK, the value of the pseudo vehicle body speed VI calculated in step S25 is updated, so that the increase from the actual vehicle body speed is corrected. The value of the control target speed VWS calculated based on is updated.
Accordingly, it is possible to avoid the occurrence of the vehicle body deceleration insufficient state due to the occurrence of the excessive decompression state.
[0067]
As described above in detail, in the embodiment of the present invention, the μ jump is determined based on whether or not the difference between the vehicle body deceleration and the vehicle body deceleration for each wheel is a predetermined value or more. Even when the road surface μ gradually changes from a low μ road to a high μ road, there is a difference between the vehicle deceleration and the vehicle deceleration for each wheel. Is obtained.
[0068]
Further, by adding a condition (step S97) when the wheel speed spin-up interval time VPT is equal to or greater than a predetermined value (600 ms) as the μ jump determination condition, the μ jump determination accuracy can be further improved. It becomes like this.
[0069]
Further, as the μ jump determination condition, a condition (step S98) is added that the vehicle body deceleration VIK is equal to or less than a predetermined value (0.4 g), that is, the low μ road determination is performed. As a result, the μ jump determination accuracy can be further improved.
[0070]
The embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration is not limited to the embodiment of the present invention, and there are design changes and the like without departing from the scope of the present invention. Are also included in the present invention.
[0071]
For example, in the embodiment of the invention, the spin-up state of the select high wheel acceleration VWDSH is determined based on 0 g. However, the present invention is not limited to this, and the spin-up state is within a range of about 0 ± 0.1 g. You may make it judge. Similarly, in the embodiment of the invention, the select high wheel speedVThe FS determines the spin-up state when the condition of VI <VFS → VI ≧ VFS is satisfied with respect to the pseudo vehicle speed VI. However, the spin is caused by the selection high wheel speed VFS returning to the vicinity of the pseudo vehicle speed VI. You may make it judge an up state.
[0072]
Further, in the embodiment of the invention, the pressure increase is performed again when the wheel acceleration VWD becomes 0 g or less, but in addition, when the wheel acceleration VWD becomes a predetermined value (5 g) or more earlier. By starting the re-pressurization, the pseudo vehicle speed VI can be made beautifully.
[0073]
【The invention's effect】
As described above, in the anti-skid control device according to claim 1 of the present invention, the vehicle body deceleration estimated by the vehicle body deceleration estimating means and the vehicle body deceleration estimating means for each wheel estimated by the vehicle body deceleration estimating means. Wheel-by-wheel decelerationDegree andMu jump determination means for determining that the road surface has changed from a low friction coefficient road to a high friction coefficient road when the difference between the two becomes a predetermined value or moreTheThis means ensures that even when the road surface μ gradually changes from a low friction coefficient road to a high friction coefficient road, the mu-The effect of being able to make jump determination is obtained.
[0074]
An anti-skid control device according to claim 2, wherein the mud is an anti-skid control device according to claim 1.-The vehicle body deceleration estimated by the vehicle body deceleration estimating unit and the vehicle body deceleration for each wheel estimated by the vehicle body deceleration estimating unit are used as mu jump determination conditions in the jump determining unit.Degree andIn addition to the difference between the two being greater than a predetermined value, the condition that the wheel speed spin-up interval time measured by the spin-up interval measuring means exceeds a predetermined value is added.-The jump determination accuracy can be further increased.
[0075]
The anti-skid control device according to claim 3 is the anti-skid control device according to claim 1, wherein-The vehicle body deceleration estimated by the vehicle body deceleration estimating unit and the vehicle body deceleration for each wheel estimated by the vehicle body deceleration estimating unit are used as mu jump determination conditions in the jump determining unit.Degree andIn addition to the difference between the vehicle speed and the vehicle body deceleration estimated by the vehicle body deceleration estimation means being not less than a predetermined value, the condition that the vehicle body deceleration is less than the predetermined value is added.-The jump determination accuracy can be further increased.
[Brief description of the drawings]
FIG. 1 is a system outline diagram showing an anti-skid control device according to an embodiment of the present invention.
FIG. 2 is a configuration diagram of a brake hydraulic pressure circuit in the anti-skid control device according to the embodiment of the invention.
FIG. 3 is a control flowchart showing basic control contents in the ECU of the anti-skid control device according to the embodiment of the invention.
FIG. 4 is a flowchart showing pseudo vehicle speed calculation contents among control contents in the ECU of the anti-skid control device according to the embodiment of the present invention.
FIG. 5 is a flowchart showing vehicle deceleration calculation contents among control contents in the ECU of the anti-skid control device according to the embodiment of the present invention.
FIG. 6 is a flowchart showing control target speed calculation contents among control contents in the ECU of the anti-skid control device according to the embodiment of the present invention.
FIG. 7 is a flowchart showing PI control calculation processing contents among the control contents in the ECU of the anti-skid control device according to the embodiment of the present invention.
FIG. 8 is a flowchart showing the decompression control contents among the control contents in the ECU of the anti-skid control device according to the embodiment of the invention.
FIG. 9 is a flowchart showing the pressure increase control contents among the control contents in the ECU of the anti-skid control device according to the embodiment of the present invention.
FIG. 10 is a flowchart showing μ jump determination contents and μ jump determination processing contents among the control contents in the ECU of the anti-skid control device according to the embodiment of the present invention;
FIG. 11 is a time chart showing control contents of the anti-skid control device of the embodiment of the invention.
FIG. 12 is a time chart showing the control contents of the conventional anti-skid control device.
[Explanation of symbols]
10 Right front wheel
12 Wheel speed sensor (wheel speed output means)
14 Left front wheel
16 Wheel speed sensor (wheel speed detection means)
20 Right front wheel
22 Front left wheel
24 Wheel speed sensor (wheel speed detection means)
26 Wheel speed sensor (wheel speed detection means)
40 ECU (braking fluid pressure control means)
50 Wheel cylinder (braking cylinder)
52 Master cylinder
54 Main liquid passage
60 Actuator unit
62 Switching control valve (switching control means)
64 reservoir
66 Hydraulic pump
VI Pseudo body speed
VW wheel speed
VWS control target speed
ZFLAG Pressure increase execution flag
GFLAG decompression execution flag
AS decompression control time
THOJI holding control time
PB target increase / decrease pulse time
VFS Select high wheel speed
LoμF Low μ flag
VIK body deceleration
x Deceleration limiter constant
VO Vehicle speed at start of decompression control
TO Vehicle deceleration creation timer
DECT decompression time timer
XX Offset value
VWD Wheel acceleration (differential value of wheel speed VW)
VWM target slip vehicle speed
INCT pressure increase timer
GAW decompression pulse
α coefficient
ZAW boost pulse
β coefficient
ΔVW deviation (deviation between target slip vehicle speed and wheel speed)
Proportion of PP deviation
KP Deviation output pulse coefficient (proportional)
IP deviation integral
KI Deviation output pulse coefficient (integration)
VWSH Spin-up point wheel speed
VPT Wheel speed spin-up interval time
VPTSH Wheel speed spin-up interval time
EVIK Car body deceleration estimated value
VWDSH Select high wheel acceleration

Claims (3)

A master cylinder that generates brake fluid pressure;
A brake cylinder disposed on each wheel of the vehicle and generating a braking force by supplying hydraulic pressure;
Switching control means capable of switching drive control to any one of a pressure reducing control state for reducing the hydraulic pressure of the brake cylinder, a holding control state for holding the hydraulic pressure, and a pressure increasing control state for increasing the hydraulic pressure;
Wheel speed detecting means for detecting the wheel speed of each wheel;
Wheel acceleration calculating means for calculating the acceleration of each wheel from the wheel speed detected by the wheel speed detecting means;
Vehicle deceleration estimation means for estimating vehicle deceleration,
When the previous value of the pseudo vehicle speed, which is the simulated vehicle speed calculated in the previous control cycle, is equal to or greater than the maximum wheel speed among the wheel speeds detected by the wheel speed detection means, the vehicle body deceleration estimation means While calculating the pseudo vehicle speed in the current control cycle by decreasing the previous value of the pseudo vehicle speed according to the vehicle body deceleration estimated in step 4, when the previous value of the pseudo vehicle speed is smaller than the maximum wheel speed A pseudo vehicle body speed calculating means for calculating a pseudo vehicle body speed this time by adding a predetermined speed to the previous value of the pseudo vehicle body speed ;
Control target speed calculation means for calculating a control target speed of the wheel in consideration of a predetermined slip ratio from the pseudo vehicle speed calculated by the pseudo vehicle speed calculation means ;
When the wheel speed detected by the wheel speed detection means becomes the control target speed calculated by the control target speed calculation means, the switching control means is switched to the pressure reduction control state to reduce the hydraulic pressure of the brake cylinder. Pressure reduction control is performed, and thereafter, the switching control means is switched to the pressure increase control state based on the wheel acceleration calculated by the wheel acceleration calculation means, and the pressure increase control for increasing the hydraulic pressure of the brake cylinder is executed. Braking fluid pressure control means;
Storage means for storing the pseudo vehicle speed at the start of the pressure reduction control ,
The vehicle deceleration estimating means determines the estimated vehicle speed at which the maximum wheel speed is switched from a larger state than prior Ki擬 similar vehicle speed in pseudo vehicle speed following state as the vehicle speed during spin-up, the estimating the vehicle deceleration from the differential value of the spin-up time of the vehicle speed and the estimated vehicle speed of pressure reduction control starting point stored in the storage means,
Is detected wheel speed for the wheel is the largest among the respective wheels by the wheel speed detecting means, switching car wheel acceleration calculated in the previous SL vehicle wheel acceleration calculating means from a larger state than zero zero following states determined as the vehicle speed at each wheel for each spin up the wheel speed of the time was, each wheel every vehicle deceleration from the differential value of each wheel every spin up when the vehicle speed and each wheel every spin up when the vehicle speed of this last time Vehicle body deceleration estimation means for each wheel to be estimated;
High coefficient of friction difference and becomes a predetermined value or more of a low friction coefficient road and the wheels per vehicle deceleration estimated by the estimated vehicle body deceleration and each wheel each vehicle deceleration estimating means by said vehicle deceleration estimating means Mu jump determination means for determining that the traveling road surface has changed on the road,
When the mu jump determining means determines that the traveling road surface has changed from the low friction coefficient road to the high friction coefficient road, the mu jump correction means for subtracting and correcting the control target speed by a predetermined value;
Anti-skid control device, characterized in that is provided. Spin for measuring the a is wheel speed spin up interval time interval between the time when the spin-up time of the vehicle speed of the current and the time of spin-up time of the vehicle speed before time Te the vehicle deceleration estimating means smell was required was determined with up interval measuring means, wherein the mu jump determination means, the difference between the vehicle deceleration the wheel each vehicle deceleration estimated the vehicle body deceleration estimated by the estimating means on each wheel for each vehicle deceleration estimating means There will be more than a predetermined value, and the previous SL vehicle wheel speed spin up interval is configured to determine that the traveling road surface of a low friction coefficient road with high friction coefficient road when equal to or larger than a predetermined value has changed The anti-skid control apparatus according to claim 1. The mu jump determination means, the difference between the vehicle deceleration the wheel each vehicle deceleration estimated the vehicle body deceleration estimated by the estimating means on each wheel for each vehicle deceleration estimating means becomes higher than a predetermined value, And when the vehicle body deceleration estimated by the vehicle body deceleration estimating means is below a predetermined value, it is determined that the traveling road surface has changed from a low friction coefficient road to a high friction coefficient road. The anti-skid control device according to claim 1.

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