JPH0375376B2 - - Google Patents

Description

Detailed Description of the Invention [Industrial Application Field] The present invention relates to a vehicle that calculates the running speed of a vehicle based on an output signal from a speed sensor that outputs a pulse train signal with a period corresponding to the running speed of the vehicle. This invention relates to a speed calculation device.

[Conventional technology]

Conventionally, anti-skid control devices have been known that drive a brake hydraulic pressure adjustment member and control the brake hydraulic pressure according to the vehicle's running condition in order to ensure vehicle steering performance and running stability when braking, and shorten the braking stopping distance. It is being In this anti-skid control device, in addition to the process of calculating the wheel speed based on the signal from the wheel speed sensor using a microcomputer, the process of estimating the vehicle (vehicle body) speed from this calculated wheel speed, etc., and the process of estimating the vehicle (vehicle body) speed from this calculated wheel speed Processing to set reference speed such as decompression judgment reference speed, actuate pattern, i.e. wheel speed,
Increase/decrease brake oil pressure according to standard speed, etc.
A number of processes are performed, such as a process of selecting a pattern for determining slow/fast.

[Problem to be solved by the invention]

Here, the process of calculating the wheel speed is normally executed in a vehicle speed interrupt routine that is separate from the main program, but in order to improve the accuracy of the calculated wheel speed (particularly the accuracy in the low speed range), for example, the rotor (inductor ) When an electromagnetic pick-up type vehicle speed sensor with a large number of teeth is used, in addition to wheel speed calculation processing which takes a relatively long time, vehicle speed interrupt routines are frequently executed, especially in high-speed ranges of the vehicle. As a result, time for other processing is squeezed and control delay becomes large. As a result, good anti-skid control is easily hindered, and the above problems are noticeable in anti-skid control systems that use only one microcomputer, especially in anti-skid control systems that calculate multiple wheel speeds with one microcomputer. It was decided to appear in

For this reason, for example, in JP-A No. 54-116982, in order to reduce the number of speed calculations at high speeds, the number of pulse signals corresponding to the speed at that time is input from the time when the previous speed calculation was performed. A speed calculation circuit is shown configured so that the next calculation is not performed until the next time.

However, according to the speed calculation circuit disclosed in the above publication, the calculation timing is set depending on the number of input pulse signals, so the calculation interval does not necessarily become longer as the speed increases. Here, at high speed, as mentioned above,
In addition to the wheel speed calculation process, the vehicle speed interrupt routine is frequently executed, so the above-mentioned conventional technology has a problem in that the load reduction due to the vehicle speed calculation is not sufficient. Furthermore, when the vehicle speed changes, for example when decelerating, not only is the calculation timing delayed, but it may not be possible to calculate an accurate speed, and when accelerating, calculations are performed in very short cycles. Therefore, the computational load may increase.

The present invention has been made in view of the above points, and it is possible to sufficiently prevent an increase in the calculation load when the vehicle speed is in a high speed range, and to perform excellent speed calculations even when the vehicle speed changes. The object of the present invention is to provide a vehicle speed calculation device that is capable of calculating vehicle speeds.

The vehicle speed calculation device according to the present invention is not only applicable to the above-mentioned anti-skid control device, but also to general vehicle travel control devices that require calculation of vehicle travel speed, such as shock absorber control. It can be applied across the board.

[Means to solve the problem]

In order to achieve the above object, a vehicle speed calculation device according to the present invention comprises: a speed sensor that generates a pulse train signal with a period corresponding to the running speed of the vehicle; counting means for counting the number of pulse signals counted by the counting means, speed calculating means repeatedly calculating the running speed of the vehicle based on the number of pulse signals counted by the counting means; The shortest calculation interval from the current calculation to the next calculation in the speed calculation means is set based on the travel speed calculated by a computation interval setting means for setting the shortest computation interval to be longer; and the shortest computation interval set by the computation interval setting means and the elapsed time from the time when the previous computation was performed by the speed computation means. and after the elapsed time becomes greater than the shortest calculation interval, permission is granted to permit the speed calculation means to calculate the traveling speed of the vehicle in response to a pulse signal that is first input. It is characterized by comprising means.

[Effect]

According to the above configuration, when the calculated travel speed is high, the shortest calculation time is set longer than when the travel speed is lower. During this shortest calculation time, only the processing of counting the pulse signals input to the counting means is performed by interrupt processing, and the calculation of vehicle speed is not performed, which greatly reduces the calculation load at high speeds. becomes possible.

Here, the next speed calculation is performed in response to the first input pulse signal after the shortest calculation interval has elapsed since the current speed calculation. Therefore, it is possible to prevent the computation cycle from becoming excessively long when the vehicle is decelerating, and it is also possible to prevent an increase in load due to speed computation when the vehicle is accelerating.

〔Example〕

Embodiments of the present invention will be described below with reference to FIGS. 2 to 15.

FIG. 2 is a flowchart for explaining the processing of a wheel speed calculation device in a vehicle travel control device that is a first embodiment of the present invention and is equipped with one vehicle speed sensor. 3 shows a vehicle speed interrupt routine according to the present invention among the processing by.

This vehicle speed interrupt routine is processed by interrupting the processing of the main routine (not shown) at the rising or falling edge of a pulse after the signal from the vehicle speed sensor, which generates a signal with a frequency proportional to the wheel speed, is waveform-shaped and amplified. is started.

In this vehicle speed interrupt routine, first, in step 51, the value Np of the counter that counts the input pulses is incremented, and then in step 52, the current time Tnow and the previous wheel speed calculation are incremented. actual time (reference time)
The time difference ΔT with Tbefor is calculated, and then in step 53, the time difference ΔT is the wheel speed calculation start permission period.
It is determined whether it is larger than Tvw.

Here, the wheel speed calculation start permission cycle Tvw is the third
As shown in the characteristic diagram in the figure, it is a function of the calculated wheel speed Vw, and the calculated wheel speed varies from low speed range to high speed range.
The previously calculated wheel speed is predetermined to have a tendency to increase as Vw increases.
This is uniquely determined in step 55, which will be described later, based on Vw.

If the time difference ΔT is less than the wheel speed calculation start permission period Tvw, the routine exits without executing any other processing.

Thereafter, when the time difference ΔT increases and becomes equal to or greater than the wheel speed calculation start permission period Tvw, step 54 is performed.
At step 54, the wheel speed Vw is calculated using a predetermined calculation formula, ie, Vw=Np×K/ΔT (1). As mentioned above, until the time difference ΔT becomes equal to or greater than the wheel speed calculation start permission period Tvw, the pulse count value
Increment processing of Np is executed sequentially, and the above
It goes without saying that Np in equation (1) is the value at which wheel speed calculation is started. Further, K in the above equation (1) is a constant predetermined based on the number of teeth of the vehicle speed sensor and the diameter of the wheel.

Next, in step 55, a wheel speed calculation start permission period Tvw is determined from the wheel speed Vw calculated in step 54 above. Note that this wheel speed calculation start permission period Tvw is determined based on the characteristics shown in FIG.

Next, in step 56, processing is performed to replace the current time Tnow with reference time Tbefor, and further, in step 57, processing is performed to clear the pulse count value to "0", and an estimated vehicle speed calculation (not shown) is performed. Returns to the main routine processing during suspension of processing in which speed calculations, etc. are executed.

In this way, in the vehicle speed interrupt routine, each time a pulse is input, the processing of the main routine is interrupted and the processing of this routine is started.
While the time difference ΔT is less than the wheel speed calculation start permission cycle Tvw, this routine is exited without performing any wheel speed calculation, and only when the time difference ΔT becomes the wheel speed calculation start permission cycle Tvw or more, the wheel speed calculation is performed and the wheel speed calculation is performed. The speed calculation start permission period Tvw is a function of the calculated wheel speed Vw, and when the calculated wheel speed Vw is a small value, the calculated wheel speed is set to a small value.
In order to have an increasing tendency as Vw increases, the vehicle speed is calculated in a relatively short period in the low speed range where the frequency of interruptions is low, so it is possible to improve the responsiveness of the calculated wheel speed. In high-speed ranges, vehicle speed calculations are performed in relatively long cycles, which makes it possible to prevent other processes, such as main routine processing, from being frequently interrupted, and as a result, for example, anti-skid control can be performed effectively. becomes possible.

Fig. 4 shows a time chart for explaining the above processing in an easy-to-understand manner, and shows the wheel speed calculation start permission period Tvw in the low speed range and high speed range when the above vehicle speed interrupt routine is started at the rising edge of the pulse. This represents the relationship between the time difference ΔT and the wheel speed calculation time.

As is clear from Fig. 4, wheel speed calculations are performed relatively frequently in the low speed range due to the relatively short wheel speed calculation start permission cycle Tvw, and in the high speed range, the wheel speed calculation start permission cycle Tvw is relatively short. Due to the long target, wheel speed calculations are performed at relatively long time intervals.

FIGS. 5 and 6 show a second embodiment of the present invention, and explain the processing of a wheel speed calculation device in a vehicle travel control device equipped with one vehicle speed sensor, similar to the first embodiment. FIG. 5 is a flowchart for the vehicle speed interrupt routine according to the present invention among the processes performed by the microcomputer in the control circuit, and FIG. 6 is a flowchart for the vehicle speed calculation according to the present invention among the processes performed by the microcomputer. A time interrupt routine is shown.

In this embodiment, while the first embodiment described above calculates the wheel speed in the vehicle speed interrupt routine,
In the vehicle speed interrupt routine, it is mainly decided whether or not to start wheel speed calculation. The speed calculation time interrupt routine is configured to perform the above-described permission/disapproval determination, thereby achieving the same effects as the first embodiment and further reducing the processing load of the vehicle speed interrupt routine.

In the vehicle speed interrupt routine shown in FIG. 5, first, in step 61, a counter value Nx for counting input pulses is incremented, and then, in step 62, the current time Tnow and the reference time Tbefor are incremented.
Then, in step 63, it is determined whether or not the time difference ΔT' is larger than the wheel speed calculation start permission period Tvw, which is similar to the wheel speed calculation start permission period Tvw in the first embodiment. Ru.

The above time difference ΔT′ is the wheel speed calculation start permission period
If it is less than Tvw, the routine exits from this routine without performing any other processing, and the suspended main routine processing is resumed.

And the time difference ΔT′ is the wheel speed calculation start permission period
As long as Tvw is less than Tvw, each time a pulse is input, only steps 61, 62, and 63 as described above are performed in sequence, and the pulse count value Np and time difference ΔT' increase.

After that, the time difference ΔT′ is the wheel speed calculation start permission period
When the wheel speed calculation flag Fvwcal is equal to or higher than Tvw, the process proceeds to step 64, where it is determined whether the wheel speed calculation flag Fvwcal is "1".

Here, the wheel speed calculation flag Fvwcal is a flag for determining permission or disapproval of wheel speed calculation performed in the calculation speed time interrupt routine, which will be detailed later, and also prepares data used for this wheel speed calculation. It is also a flag that gives instructions.

If this wheel speed calculation flag Fvwcal is "0", the process proceeds to step 65, and in steps 65 to 69, the pulse count value Nx and time difference ΔT' at the time of execution of the current vehicle speed interrupt routine are calculated as the wheel speed calculation time interrupt. The pulse count value Np, which is the data for the wheel speed calculation executed in the routine, is held as the time difference ΔT, and the pulse count value Nx is cleared and the reference time is
Tbefor update processing and wheel speed calculation flag
Fvwcal setting processing is performed sequentially.

Then, the time difference ΔT′ based on the reference time updated as above is the wheel speed calculation start permission period Tvw
While it is less than Tvw, only the processing consisting of Step 61, Step 62, and Step 63 is executed, and then the time difference ΔT' becomes equal to the wheel speed calculation start permission period Tvw.
If the wheel speed calculation has not been executed even after the above, the wheel speed calculation flag Fvwcal is still "1", so the processing in steps 65 to 69 is not executed, and at least after the wheel speed calculation has been executed. If not, new data Np and ΔT for the next wheel speed calculation will not be prepared.

On the other hand, in the wheel speed calculation time interrupt routine of FIG. 6, first, in step 71, it is determined whether the wheel speed calculation flag Fvwcal is "1", in other words, whether wheel speed calculation may be performed. It is determined whether

If this wheel speed calculation flag Fvwcal is "0", then in step 72 a time interval (time interrupt period) T'vw for starting execution of the next wheel speed calculation time interrupt routine is predetermined. Perform processing to set a fixed time Ta, that is, interrupt set,
Exit this routine.

Thereafter, in the vehicle speed interrupt routine described above, when the wheel speed calculation data Np and ΔT are prepared and the wheel speed calculation flag Fvwcal is set to "1", the process advances to step 73, and the above (1) is executed. Wheel speed using the same calculation formula as Eq.
Vw is calculated, and then in step 74, the wheel speed calculation start permission period in the vehicle speed interrupt routine is determined.
Based on the wheel speed Vw calculated in step 74, Tvw is determined according to the characteristics shown in FIG. Then, in step 76, the wheel speed calculation flag is calculated as a function of
Clear Fvwcal to "0" and exit this routine.

Therefore, since the wheel speed calculation flag Fvwcal becomes "0" after wheel speed calculation is performed, preparation of new data Np and ΔT for the next wheel speed calculation is permitted in the vehicle speed interrupt routine. becomes.

As described above, in this embodiment, the data Np and ΔT for wheel speed calculation are prepared in the vehicle speed interrupt routine, and the data Np and ΔT are used to calculate the wheel speed in the wheel speed calculation time interrupt routine. Compared to the first embodiment described above, the processing load of the vehicle speed interrupt routine can be reduced, and as a result, the time during which the processing of the main routine is interrupted can be shortened.

FIG. 7 is a system diagram schematically showing the overall configuration of an anti-skid control system to which the present invention is applied, which is installed in a rear-wheel drive vehicle and has three vehicle speed sensors.

In the figure, 1 to 4 represent each wheel of the vehicle; 1 is the right front wheel, 2 is the left front wheel, 3 is the right rear wheel, and 4 is the left rear wheel. Numerals 5 to 7 are electromagnetic pickup type or photoelectric conversion type vehicle speed sensors for detecting the wheel speed, respectively. Of these, 5 is attached near the right front wheel 1, and
A right front wheel speed sensor 6 is attached near the left front wheel 2 and generates a signal with a frequency proportional to the rotational speed of the right wheel 1 according to the rotation of the right front wheel 2. A left front wheel vehicle speed sensor 7 that generates a similar signal is attached to a propeller shaft 8 that transmits power to the right rear wheel 3 and left rear wheel 4, which are drive wheels, and is connected to the right rear wheel 3 and the right rear wheel 3 according to the rotation of the propeller shaft 8. This is a rear wheel speed sensor that generates a signal with a frequency proportional to the average rotational speed of the left rear wheel 4. Reference numerals 9 to 12 are hydraulic brake devices, respectively: the hydraulic brake device 9 is attached to the right front wheel 1, the hydraulic brake device 10 is attached to the left front wheel 2, the hydraulic brake device 11 is attached to the right rear wheel 3, and the hydraulic brake device 12 is attached to the left rear wheel. They are arranged in 4 respectively. 13 is a brake pedal; 14 is a stop switch for detecting braking or non-braking depending on the state of the brake pedal 13; 15 is a hydraulic cylinder that generates brake hydraulic pressure when the brake pedal 13 is depressed;
6 represents a hydraulic pump that generates oil pressure according to engine rotation. 17 to 19 are hydraulic cylinders 1
5 and a hydraulic pump 16 according to the output from an electronic control circuit (control circuit) 26 (described later), and is an actuator that sends it to the hydraulic brake devices 9 to 12, of which 17 is the hydraulic brake device for the right front wheel 1. Right front wheel actuator for 9;
18 is a left front wheel actuator for the hydraulic brake device 10 for the left front wheel 2, and 19 is a rear wheel actuator for the hydraulic brake devices 11 and 12 for the rear wheels 3 and 4. 20 to 23 are actuator 1
7 to 19 to hydraulic brake device 9 to 12
20 of these are hydraulic pipes provided between the right front wheel actuator 17 and the hydraulic brake device 9 of the right front wheel 1, and 21 are hydraulic pipes provided between the left front wheel actuator 18 and the hydraulic brake device 9 of the right front wheel 1. A hydraulic pipe line provided between the hydraulic brake device 10 of the left front wheel 2, 22 a hydraulic pipe line provided between the rear wheel actuator 19 and the hydraulic brake device 11 of the right rear wheel 3, and 23 a rear wheel. A hydraulic conduit provided between the actuator 19 and the hydraulic brake device 12 of the left rear wheel 4 is shown. 24 is a main relay that switches the electrical connection between the electromagnetic solenoids of the actuators 17 to 19 and the power supply source according to the output of the electronic control circuit 26, and 25 is an anti-skid control device when the electromagnetic solenoid or the stop switch 14 is disconnected. This represents an indicator lamp for notifying the driver that an abnormality has occurred in the system in accordance with the output of the electronic control circuit 26 when a failure occurs in the system. An electronic control circuit 26 receives signals from the vehicle speed sensors 5 to 7 and the stop switch 14, performs arithmetic processing for anti-skid control, and controls the actuator 1.
7 to 19 represent those that generate outputs that control the main relay 24 and indicator lamp 25.

The right front wheel actuator 17, the left front wheel actuator 18, and the rear wheel actuator 19 are each connected to a hydraulic pump 16
Regulator part 2 that adjusts the hydraulic pressure from
7, a control valve section 28 including an electromagnetic solenoid for increasing/decreasing control for switching the direction of increase/decrease of brake oil pressure, and an electromagnetic solenoid for slow/sudden control for switching the gradient of increase/decrease of brake oil pressure into two stages, slow and fast. The hydraulic pressure adjustment unit 29 includes a brake hydraulic pressure adjustment unit 29, and the hydraulic pressure output from each actuator is applied to the brake and hydraulic pressure of each hydraulic brake device via each hydraulic pipe line.
The signal is transmitted to the wheel cylinders and brakes are applied to each wheel. In addition, the electromagnetic solenoid for increase/decrease control decreases the hydraulic pressure when energized, and
For example, the electromagnetic solenoid for sudden control is designed to have a steep increase/decrease gradient when energized.

The electronic control circuit 26 has a circuit configuration as shown in FIG. 9, and 30 to 32 in the figure are waveform shaping amplifier circuits, respectively. The waveform shaping amplifier circuit 30 processes the signal of the vehicle speed sensor 5 by a microcomputer 35. A pulse signal suitable for
The other waveform shaping amplifier circuits 31 and 32 are also configured to convert the signals from the vehicle speed sensors 6 and 7 into similar pulse signals. 33 is the stop switch 14
34 is a power supply circuit for supplying a constant voltage to the microcomputer 35 etc. when the ignition switch 41 is turned on; 35 is a CPU 35a and a ROM 3;
5b, a RAM 35c, an I/O circuit 35d, and the like. Reference numerals 36 to 40 each indicate a drive circuit that outputs an output according to a control signal from the microcomputer 35. Of these, 36 is a right front wheel actuator drive circuit for driving the electromagnetic solenoid of the right front wheel actuator 17, and 37 is a drive circuit for the left front wheel. Actuator 18
Left front wheel actuator drive circuit for driving the electromagnetic solenoid, 38 is the rear wheel actuator 1
9 is a rear wheel actuator drive circuit for driving an electromagnetic solenoid, 39 is a main relay drive circuit for energizing the coil 24b of the main relay 24 having a normally open contact 24a to close the normally open contact 24a, and 40 is an indicator. An indicator lamp drive circuit for lighting the lamp 25 is shown.

Next, the processing and operation of the anti-skid control device configured as described above will be explained.

When the ignition switch 41 is turned on,
A constant voltage from the power supply circuit 34 is applied to the microcomputer 35 etc.
The CPU 35a of No. 5 starts executing arithmetic processing according to a program stored in advance in the ROM 35b.

FIG. 10 is a schematic flowchart showing the main part of this arithmetic processing. In this processing, first, only at the start of processing, initialization processing for subsequent processing is performed, for example, setting of various flags to be described later. Perform a reset, etc.

Thereafter, steps 102 and 103 are performed depending on the determination result at step 107.
and step 104 and step 105 and step 1
A series of processes consisting of step 06 and step 107, or step 102, step 103, step 104, step 105, step 106, step 107, step 108, and step 10
A series of processes consisting of 9 is repeatedly executed until the ignition switch 41 is turned off.

In this series of processing, step 102
A control permission determination process and a control start determination process are executed. That is, when calculating the estimated vehicle speed in estimated vehicle speed calculation processing step 104, which will be described later,
In addition to setting and resetting the permission flag Fact for instructing to change the selection of the wheel speed that is one of the plurality of estimated vehicle speed candidates, it also instructs to change the processing content of the traveling route determination processing step 103, which will be described later. Actuate pattern selection step 30 in the timer interrupt routine
6, etc., and a start flag for instructing the selection of a reference speed to be calculated in step 105 of the reference speed calculation processing described later.
Performs Fsta set/reset processing.

Next, in step 103, the coefficient of friction and the unevenness of the road surface are estimated based on the type of road the vehicle is currently traveling on, the road surface condition, etc. It is either a medium μ road such as Torsphalt, or a low μ road such as an icy road, a so-called good road with a very gentle degree of unevenness, a so-called bad road with a certain degree of roughness, or a low μ road such as an icy road. A driving route determination process is executed to determine the nature of the road itself, such as a so-called extremely bad road (including a wavy road), which is extremely likely to cause problems for anti-skid control, based on specific conditions. To roughly describe the content of this discrimination process, each vehicle speed sensor 5,
Corresponding wheel speed Vw data calculated in the wheel speed calculation time interrupt routine described later based on the signals from 6 and 7 (however, the wheel speed of the rear wheel is based on the actual wheel speed of the right rear wheel 3 and the left rear wheel speed). This corresponds to the average wheel speed with the actual wheel speed of wheel 4.)
Based on the wheel acceleration Vw data, multiple levels of reference acceleration data stored in advance in the ROM 35b, and multiple reference speed data calculated in reference speed calculation processing step 105, for each individual wheel,
Processing corresponding to the magnitude comparison of various combinations of wheel speed, wheel acceleration, and reference speed and reference acceleration is performed, and the value of a counter that is incremented or decremented according to the processing result is compared with a predetermined set value. A size comparison is performed, and a travel path is finally determined based on the comparison result.

Next, in step 104, estimated vehicle speed calculation processing is executed. To give an overview of this process, when creating estimated vehicle speed data, there are three candidate speeds: the calculated wheel speed and the driving acceleration that can be obtained from the actual vehicle driving state (including during braking). The speed consisting of the upper and lower limit values, and the first and second estimated vehicle speeds calculated using two calculation formulas based on the estimated vehicle speed calculated in the previous estimated vehicle speed calculation process, etc. This value is determined as the estimated vehicle speed. In this case, the wheel speed, which is one of the candidate speeds, is the intermediate value of the three wheel speeds during the period in which the permission flag Fact is in the reset state as described above in the control permission/start determination processing step 102. On the other hand, during the period when the permission flag Fact is set, the wheel speed that takes the maximum value is selected as a candidate.

Next, in step 105, a reference speed calculation process is executed. The outline of this process is that until the start flag Fsta is reversed from the reset state to set, that is, until the start of depressurization (which can also be called the start of control), a control start judgment reference speed is calculated, and the start flag Fsta is After the setting, that is, after the start of control, the standard speed for road noise (vehicle body vibration) countermeasures to prevent malfunction of the actuators 17 to 19 due to road noise, electrical noise, etc., and the depressurization, which is one of the standards for starting depressurization. The data corresponding to the judgment reference speed, the intermediate μ judgment reference speed which is a reference for determining an intermediate μ road, and the low μ judgment reference speed which is a reference for determining a low μ road are at least estimated vehicle speed. It is created from a predetermined arithmetic expression including: Note that the control start determination reference speed is set in step 103 of the traveling route determination process in order to prevent at least one of the actuators 17 to 19 from starting an undesired pressure reduction due to slow braking, especially on a rough road. The value of the subtracted number in the arithmetic expression is made variable depending on the characteristics of the road itself determined in . In addition, for the road noise (vehicle body vibration) countermeasure standard speed and decompression judgment standard speed, the value of the subtracted number in the corresponding calculation formula is variable, and the decompression speed standard can be switched depending on the road condition. Overcontrol prevents excessive depressurization.

Next, in step 106, a system abnormality check is executed. In this process, the ROM35b
Compare and examine the data corresponding to the operating state of the system element during normal system operation stored in advance with the data representing the operating state of the system element captured during the processing, and if it is determined that the system is abnormal. An abnormality flag indicating the system operating state is set, and if it is determined that there is no abnormality, the abnormality flag is held in a reset state or reversed.

Next, in step 107, the abnormality flag is checked to determine whether or not there is a system abnormality. If it is determined that the abnormality flag is not set, that is, if the system is operating normally, the process proceeds to step 102 of the control permission and start determination process as described above. On the other hand, if it is determined that the abnormality flag is set, that is, if an abnormality has occurred in the system or the system is operating abnormally, steps 108 and 109 are sequentially executed, and the control permission and start determination described above are performed. Proceed to processing step 102.

Step 108 is a step for notifying the driver that an abnormality has occurred in the system so that he can confirm that the anti-skid control is not effective. A control signal for lighting the indicator lamp is output to the indicator lamp drive circuit 40 only when it is first determined that the occurrence of the error occurs. Indicator lamp drive circuit 40, which receives this control signal, latches this control signal so that indicator lamp 25 continues to be lit. This step 108
In this case, after outputting the control signal as described above, a process is also executed to output a control signal to the indicator lamp drive circuit 40 to turn off the indicator lamp 25 when the system automatically returns to the normal operating state. You can do it like this.

Step 109 is a step for performing fail-safe processing in the event of abnormal system operation.
7, 18, and 19, regardless of the driving state of the electromagnetic solenoid for increase/decrease control and the electromagnetic solenoid for slow/sudden control at that time, the non-antiskid control mode, that is, the brake oil pressure according to the depression of the brake pedal 13. In order to switch to the normal mode in which braking is performed by the main relay 24, a process is performed to output a control signal to cut off the energization to the coil 24b of the main relay 24. When the coil 24b is no longer energized, the previously closed normally open contact 24a is switched to its normally open state, thereby cutting off the power supply to the electromagnetic solenoids in each of the actuators 17, 18, 19, and at least Normal brake control is performed until the system abnormality is resolved. In this system fail-safe processing step 109, in order to further improve safety, the power supply is cut off as described above, and a control signal is output to each actuator drive circuit 36, 37, 38 to turn off the electromagnetic solenoid. It is also possible to perform the following processing at the same time.

11, 12, and 13 are flowcharts showing the processing of the vehicle speed interrupt routine, which is executed by temporarily interrupting the processing of the main routine as described above. The right front wheel speed interrupt routine starts processing in synchronization with either the rising edge or the falling edge of the input pulse after the signal from the right front wheel speed sensor 5 is waveform-shaped and amplified by the waveform shaping amplification circuit 30. Similarly, FIG. 12 shows a left front wheel speed interrupt routine in which processing is started in synchronization with either the rising or falling edge of the input pulse corresponding to the left front wheel speed sensor 6, and FIG. 7 represents a rear wheel vehicle speed interrupt routine whose processing is started in synchronization with either the rising or falling of the input pulse corresponding to 7, and these three vehicle speed interrupt routines require simultaneous generation of multiple pulses. A priority order is given in advance.

In the right front wheel speed interrupt routine shown in FIG.
Steps 201a to 209a are respectively step 6 in the flowchart of FIG. 5 representing the processing in the second embodiment as described above.
There is a one-to-one correspondence with each step from step 1 to step 69, and, similarly to the processing in the second embodiment, pulse number data is mainly used to calculate the right front wheel speed.
Npfr, the time difference data ΔTfr are prepared under at least the following conditions: right front wheel speed calculation start permission period Tvwfr where the time difference ΔT′fr is variable according to the calculated wheel speed.
This will be done on the condition that the period has passed. And prepared pulse number data Npfr, time difference data ΔTfr
is used when calculating the right front wheel speed in wheel speed calculating step 301 in the time interrupt routine of FIG. 14, which will be described later.

The left front wheel speed interrupt routine and the first
As is clear from the figure, the rear wheel speed interrupt routine in FIG. 3 carries out the same processing as the right front wheel speed interrupt routine in FIG. In the rear wheel speed interrupt routine, pulse number data Nprr and time difference data ΔTrr for rear wheel speed calculation are prepared, respectively.

FIG. 14 is a flowchart showing, in part, the processing of a time interrupt routine that starts execution at a variable period depending on the calculated wheel speed.

In this time interrupt routine, first, in step 301, a process of calculating the wheel speed of each wheel is executed.

The detailed processing at step 301 is shown in a flowchart as shown in FIG. The processing by the wheel speed calculation step 301 will be described above with reference to the flowchart shown in FIG.

In the wheel speed calculation step 301, first, in step 301a, it is determined whether the wheel speed for which wheel speed calculation was performed recently in the past is related to the left front wheel 2 or not, and whether or not the flag Fcal is "0". Judgment is made by determining. Here, the value of the flag Flcal can be "0", "1", or "2", and if it is "0", it indicates that the wheel speed calculation of the left front wheel 2 was performed in the recent past. If it is "1", it means that the wheel speed of the right front wheel 1 has been calculated in the same way, and if it is "2", the average wheel speed of the rear wheels 3 and 4 has been calculated in the same way. This means that the value of the flag Flcal is set immediately after the wheel speed calculation is performed, as will be described later.

Assuming that the average wheel speed of rear wheels 3 and 4 has been calculated recently, the value of the flag Flcal is set to "2", so step 30 is executed.
When the determination result of step 1a is "NO", the process proceeds to step 301b, and in step 301b, a flag Flcal is set to determine whether or not the wheel speed for which wheel speed calculation was recently performed in the past is related to the right front wheel 1. The determination is made by determining whether or not is "1".

In this case, since the flag Flcal is set to "2", the determination result in step 301b is "NO" and the process proceeds to step 301c1.
In this step 301c1, by determining whether or not the flag Fvwfcal is "1", the data Npfr and ΔTfr for calculating the right front wheel speed have already been prepared in the right front wheel speed interrupt routine shown in FIG. Determine whether or not there is.

Assuming that the data Npr and ΔTfr are not yet prepared, the process proceeds to step 301c2, and in this step 301c2, the flag Fvwflcal is set to "1".
By determining whether or not the 12th
In the left front wheel speed interrupt routine shown in the figure, it is determined whether data Npfl and ΔTfl for left front wheel speed calculation are prepared.

Assuming that the data Npfl and ΔTfl are not yet prepared, the process proceeds to step 301c3, and in this step 301c3, the flag Fvwrrcal is set to "1".
By determining whether or not the 13th
In the rear wheel speed interrupt routine shown in the figure, it is determined whether data Nprr and ΔTrr for rear wheel speed calculation are prepared.

Assuming that the data Nprr and ΔTrr are not prepared, the process proceeds to step 301d, where the time interval T'vw for starting the next time interrupt routine execution is set to a relatively short fixed time Ta.
Then, the process proceeds to step 302 in FIG. 14.

In this way, when the most recent wheel speed calculations are related to the rear wheels, priority is given to the right front wheel speed calculation, the left front wheel speed calculation, and the rear wheel speed calculation in this order. In addition, in this case, the first
If data for wheel speed calculation is not prepared in any of the vehicle speed interrupt routines shown in Figures 1 to 13, wheel speed calculation is prohibited, and the data for the next time interruption is mainly used. There is only a process of setting a fixed time interval.

Then data Npfr for right front wheel speed calculation,
Assuming that ΔTfr has been prepared, the flag Fvwfrcal is set to "1" in step 209a of FIG.
At e4, in the same way as the processing in steps 73 to 76 in the wheel speed calculation time interrupt routine of FIG. 6 described above, the right front wheel speed Vwfr is calculated, the right front wheel speed calculation start permission cycle Tvwfr is set,
Data for setting the time interval T′vw for the next time interrupt occurrence and calculating the next right front wheel speed.
Processing is performed to allow the preparation of Npfr, ΔTfr,
Furthermore, in step 301e5, a process is performed to set the flag Flcal to "1" to indicate that the wheel speed calculation performed in the recent past is related to the right front wheel, and step 3 in FIG.
Proceed to 02. The right front wheel speed calculation start permission cycle Tvwfr is made variable as a function of the calculated wheel speed Vw, similar to the first and second embodiments described above, and has the characteristics shown in FIG. Further, the time interval T'vw for generating the time interrupt is also made variable as a function of the calculated wheel speed Vw, giving characteristics almost similar to those shown in FIG.

The flag is set in step 301e5 as described above.
Since Flcal is set to "1", in the next wheel speed calculation step 301, step 3 is set.
The determination result of step 01b is "YES", and therefore the process advances to step 301f1.
Data for left front wheel speed calculation at 01f1
Determine whether Npfl and ΔTfl are prepared.

If the data Npfl and ΔTfl are not prepared, the process proceeds to step 301f2, and in step 301f2 data for rear wheel speed calculation is
It is determined whether or not Nprr and ΔTrr are prepared. If the data Nprr and ΔTrr are not prepared, the process proceeds to step 301f3, and in step 301f3, data for calculating the right front speed is determined.
It is determined whether or not Npfr and ΔTfr are prepared, and if the data Npfr and ΔTfr are not prepared, the fixed time Ta is set as the time interval T'vw for the next time interrupt generation in the next step 301d. After the settings have been made, the process advances to step 302 in FIG.

In the wheel speed calculation step 301 immediately after the right front wheel speed calculation is performed, priority is given in the order of left front wheel speed calculation, rear wheel speed calculation, and right front wheel speed calculation, and all of these wheel speed calculations are given priority. If the data is not prepared for
The routine exits after setting the time interval T'vw for the next time interrupt occurrence.

Thereafter, when the data Npfl and ΔTfl for left front wheel speed calculation, which have the highest priority, are prepared before preparing other wheel speed calculation data, the process advances to step 301g1, and in steps 301g1 to 301g5, Front wheel speed calculation, setting of left front wheel speed calculation start permission period Tvwfl, setting of time interval T′vw for the next time interrupt occurrence, data Npfl, ΔTfl for next left front wheel speed calculation
A process is performed in which the flag Flcal is set to "0" to indicate that the wheel speed calculations performed in the recent past relate to the left front wheel.

Since the flag Flcal is set to "0" as described above, the next wheel speed calculation step 301 is started.
The determination result in step 301a is "YES".
Then, the process advances to step 301h1, and in this step 301h1, rear wheel speed calculation data NPrr,
It is determined whether ΔTrr is prepared.

If the data Nprr and ΔTrr are not yet prepared, the process proceeds to step 301h2, and in step 301h2, the right front wheel speed calculation data is
It is determined whether Nprr and ΔTfr are prepared.

If the data Npfr and ΔTfr have not yet been prepared, proceed to step 301h3.
In this step 301h3, it is determined whether the left front speed calculation data NPfl and ΔTfl are prepared.

If the data Npfl and ΔTfl have not yet been prepared, the process proceeds to step 301d, where the time interrupt period is determined.
A process for setting T'vw to a fixed time Ta is executed, and the process advances to step 302 in FIG.

After that, assuming that the above data Nprr and ΔTrr are prepared, the determination result in step 301h1 becomes "YES", steps 301i1 to 301i5 are sequentially executed, and the rear wheel speed Vwrr
is calculated, etc. Note that the flag Flcal is set to "2" indicating that the rear wheel speed has been calculated recently.

In this way, in the wheel speed calculation step 301, it is determined whether the wheel speed recently calculated in the past relates to the front right wheel, the front left wheel, or the rear wheel, and the calculation is performed next time according to this determination result. The processing is the same as the processing by the wheel speed calculation time interrupt routine in the second embodiment described above, except that priority is given to the wheels related to the wheel speeds to be determined so that there is no variation in the calculation frequencies for these three wheels. processing is performed.

After this wheel speed calculation step 301 is executed, a process of calculating the wheel acceleration of each wheel is executed at step 302 in FIG.
In this wheel acceleration calculation step 302,
a speed difference between the wheel speed calculated by executing the wheel speed calculation step 301 and the wheel speed calculated by the previous wheel speed calculation step 301;
A predetermined arithmetic expression including time and constants is calculated, and filter processing is also performed as necessary.

Next, in step 303, it is determined whether or not the permission flag Fact described above in FIG. If the permission flag Fact is set, the route consisting of steps 305 to 308 is sequentially executed.

In step 304 above, the permission flag
During the first process after resetting Fact, a process is performed in which a control signal for this purpose is output to each of the actuator drive circuits 36, 37, and 38 in order to return all the actuators 17, 18, and 19 to the non-operating state. . Each of the actuator drive circuits 36, 38, and 38 to which this control signal is input maintains a state corresponding to this control signal, stops energizing the electromagnetic solenoid of the corresponding actuator, and brake hydraulic pressure control is performed in the energization mode. Make it. Note that the above output processing does not need to be performed in the second and subsequent processing after the permission flag Fact is reset. After passing through this output step 304, the interrupted process shown in FIG. 10 continues to be executed.

On the other hand, in step 305 executed when the permission flag Fact is set, each wheel speed and each wheel acceleration calculated in the wheel speed calculation step 301 and the wheel acceleration calculation step 302, and the reference speed calculation in FIG. A process of comparing various reference speeds calculated in processing step 105 with various preset reference accelerations is executed.

Next, in step 306, the comparison step 3 is performed.
Based on the results obtained in step 05, a process is executed to select a drive pattern for each of the increase/decrease control electromagnetic solenoid and the slow/sudden control electromagnetic solenoid. Note that various drive patterns corresponding to each solenoid are stored in advance in the ROM 35b.

Next, in step 307, the continuous time of the pressure increase mode and pressure reduction mode is monitored, and if the pressure reduction mode continues for longer than the time predicted to be impossible based on normal anti-skid control, a permission flag is set. The actuator pattern selection step 306 is selected in order to determine that there is a system abnormality even if the actuators 17, 18, and 19 are being set, and force all the actuators 17, 18, and 19 to be inactive in the next step 308. A process for changing the drive pattern is executed.

Next, in step 308, a process is executed to output a control signal corresponding to the final drive pattern to the corresponding actuator drive circuits 36, 37, and 38. The actuator drive circuits 36, 37, and 38 to which this control signal has been input respectively drive the corresponding actuator 1 according to this control signal.
A drive output is performed to determine the drive state of 7, 18, and 19. After going through this output step 308, typically
The process shown in FIG. 10, which has been interrupted, continues to be executed.

〔effect〕

As described above, according to the present invention, it is possible to prevent an increase in calculation load when the vehicle speed is in a high speed range. Furthermore, it is possible to perform excellent speed calculations even when the vehicle speed changes, such as when the vehicle accelerates or decelerates.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing the basic configuration of the present invention, Fig. 2 is a flowchart showing the processing in the first embodiment of the invention, and Fig. 3 is the wheel speed Vw of the wheel speed calculation start permission period Tvw. Figure 4 shows the wheel speed calculation start permission period Tvw, time difference ΔT, and wheel speed calculation time when the wheel speed is in the low speed range, and the wheel speed calculation start permission when the wheel speed is in the high speed range. Period Tvw, time difference ΔT,
A time chart showing the difference from the wheel speed calculation time is shown. FIGS. 5 and 6 show the second embodiment of the present invention.
FIG. 5 shows a flow chart of the vehicle speed interrupt routine, and FIG. 6 shows a flow chart of the wheel speed calculation time interrupt routine. 7 to 15 show a vehicle anti-skid control device to which the present invention is applied, FIG. 7 is a system diagram schematically showing the entire system, and FIG. 8 shows the actuator (adjustment member) in FIG. 7. 17, 18, and 19; FIG. 9 is a block diagram showing the internal configuration of the control circuit 26 in FIG. 7 and electrical connections between the control circuit 26 and peripheral devices; FIGS. The figure is a flowchart showing the processing by the microcomputer 35 in the control circuit 26. Fig. 10 is a flowchart showing the main routine, and Figs. A flowchart showing a vehicle speed interrupt routine corresponding to the rear wheels; FIG. 14 is a flowchart showing a time interrupt routine;
FIG. 15 is a flowchart showing the processing contents of the wheel speed calculation step in the time interrupt routine of FIG. 14. 5, 6, 7...Vehicle speed sensor, 9, 10, 11,
12... Hydraulic brake device, 17, 18, 19...
...actuator, 26...electronic control circuit.

Claims (1)

[Claims] 1. A speed sensor that generates a pulse train signal with a period corresponding to the running speed of the vehicle; and a counter that receives the input pulse train signal from the speed sensor and counts the number of input pulse signals by interrupt processing. means for repeatedly calculating the traveling speed of the vehicle based on the number of pulse signals counted by the counting means; Setting the shortest calculation interval from the current calculation to the next calculation in the speed calculation means, and setting the shortest calculation interval longer when the traveling speed is high compared to when the traveling speed is low. A calculation interval setting means compares the shortest calculation interval set by the calculation interval setting means with the elapsed time from the time when the previous calculation was performed by the speed calculation means, and determines whether the elapsed time is the shortest. A vehicle characterized by comprising: permission means for permitting the speed calculation means to calculate the traveling speed of the vehicle in response to a first input pulse signal after the calculation interval has exceeded the calculation interval. Speed calculation device.