JPH03215751A - Acceleration arithmetic unit for vehicle - Google Patents

Abstract

PURPOSE:To improve the response by finding calculating acceleration or deceleration from (V1-V0)/T based upon a mean vehicle speed V0 at time t0 and a mean vehicle speed V1 at time t0+T. CONSTITUTION:When vehicle speed pulses are inputted from the reed switch 3a of a vehicle speed sensor 3 to a controller 1, the measurement time T of the acceleration or deceleration is set and the acceleration or deceleration begins to be measured. Then the period by the latest one pulse is measured by the sensor 3 and the vehicle pulse period is stored by replacing a period which is N pulses before. The latest pulse period is averaged to calculate and store the mean vehicle speed. Then the mean vehicle speed which is calculated this time and a mean vehicle speed which is calculated one pulse before are compared with each other to decide an acceleration or deceleration state, and the decision result is stored. When a measurement time T is elapsed from the start of the measurement of the acceleration or deceleration, the acceleration is calculated from (V1-V2)/T, where V1 is the mean vehicle speed V1 which is calculated finally and V0 is an initial speed stored at the start of the measurement.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a vehicle acceleration calculation device that is effective for use in electronically controlled suspension devices of automobiles, etc. [Prior Art] Conventionally, a system for detecting braking of a vehicle and switching the stiffness of the suspension is disclosed in, for example, Japanese Patent Application Laid-Open No. 56-427.
This method has been proposed in Publication No. 39 and Japanese Unexamined Patent Publication No. 148710/1983. All of these detect the braking state of the vehicle using signals from the brake switch. Brake switches are installed in most cars because they turn on the brake lights while braking, and they are easy to use as a signal. It is not possible to detect up to [Problems to be Solved by the Invention] The conventional system is configured as described above, and since the brake switch does not provide a signal that represents the deceleration of the vehicle body, it cannot be used at sudden decelerations of, for example, -0.3G (acceleration) or more. It has the disadvantage that it is not suitable for fine-grained and subtle suspension control, such as changing the suspension to a hard setting. Furthermore, during deceleration when the brake switch is not operated, such as during engine braking, no detection is possible at all, and of course, no detection is possible during sudden acceleration.

Therefore, as a method of directly detecting the deceleration and acceleration of the vehicle, it is possible to obtain the acceleration/deceleration by differentiating the vehicle speed information obtained from the signal from the remote sensor. When using a general vehicle speed pulse detected by a vehicle speed pulse, the resolution is poor because only 4 vehicle speed pulses are obtained per wheel rotation. As a result, the calculation accuracy is poor, and vibrations in the speedometer cable cause fluctuations in the vehicle speed pulse (fluctuations in the pulse period), resulting in false detections if you try to improve the detection response. was there. The simplest way to prevent this false detection is to lengthen the summer cycle T of G and increase the number of vehicle speed pulses counted during T to avoid noise caused by vibrations of the engine and cables, etc. This is the required response value required from suspension control of 100+
*Incompatible with s~200as. This invention was made to solve the above-mentioned problems, and its purpose is to obtain a vehicle acceleration calculation device that can satisfy the contradictory demands of improving the responsiveness and accuracy of vehicle speed pulse signals. do.

[Means to solve the problem]

The vehicle acceleration calculation device according to the present invention calculates the actual value of acceleration/deceleration based on the average vehicle speed v0 at time t0 and the average vehicle speed v0 at time t. Average vehicle speed V at 10T, and α. =V, -V, and a means to find T. [Function] The above means in the present invention always obtains the average vehicle speed from the period of N vehicle speed pulses during the time T, determines whether the change in the average vehicle speed is acceleration or deceleration, and if the change in the average vehicle speed during the time T changes from acceleration to deceleration, and if << changes from slow speed to acceleration, the calculation of addition/subtraction is stopped at that point, and a new time T is calculated.
is set, the acceleration/deceleration calculation is started, and the acceleration/deceleration calculation is performed when the average vehicle speed or acceleration state is always maintained during the time T, or when the deceleration state is maintained. [Embodiment] Hereinafter, an embodiment of the vehicle acceleration detection device of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram of a suspension system incorporating a vehicle acceleration calculation unit 1 according to the present invention. The connecting passage 10 between the variable orifice 6 and the air spring 9 in 5 is opened and closed. The brake switch 2 is turned on by depressing the brake pedal l2. In addition, the vehicle speed sensor 3 includes a reed switch 3a and a plurality of (in this embodiment, SN
a disk-shaped magnet 3b having N and S poles (4 poles each);
The wire 3c is connected between the wheel 7 and the magnet 3b, and as the wheel 7 rotates, the wire 3c rotates the magnet 3b, and the reed switch 3a facing it rotates between the magnetic poles S and N. It turns on and off each time they face each other. This on. The off pulse signal is sent to the control device 1 to calculate the vehicle speed.

A shock absorber 5 is connected between the vehicle body 4 and the arm 8. Furthermore, the air spring 9 has spring chambers 9a and 9b, and a connecting passage 10 is provided between the two spring chambers 9a and 9b. When the connecting passage 10 is opened, the spring chambers 9a and 9b are brought into communication. When the connection passage 10 is closed, the spring constant increases and becomes stiff. Note that l1 is an auxiliary spring for the air spring 9, and is connected between the vehicle body 4 and the arm 8. Furthermore, in the shock absorber 5, when the orifice diameter of the oil passage therein is switched to "large" by the actuator 6, the damping rate decreases, and conversely, when the orifice diameter is switched to "small", the damping rate increases. ．． Although only one side of the front wheels is shown in FIG. 1, the remaining wheels are also equipped with suspension devices in the same manner as described above.

Further, a vehicle height sensor 14 is attached to the vehicle body 4,
This vehicle height sensor l4 is connected to the arm 8 via an arm 10.15, and the control device l uses the output signal of the vehicle height sensor l4 as input to control the vehicle height adjusting means 13 to adjust the air pressure of the air spring 9. By raising or lowering the height, it is possible to adjust to any target vehicle height.

Next, a method of calculating vehicle speed and acceleration/deceleration from the output of the vehicle speed sensor 3 in the suspension system configured as described above will be explained. Figure 2 shows the output waveform of the vehicle speed sensor 3. Now, the on-off signal of the reed switch 3a or the pulse signal after waveform shaping after removing chattering, noise, etc. has the following characteristics.

First, the first component is a component due to machining errors such as eccentricity of the magnet 3b, and as in this embodiment, there are four pulses 101 per rotation.
What if it outputs ~104? , -14, each period becomes a factor of error. The second error is wire 3c
This is due to the rope-jumping phenomenon of t. 1,,1...t. This causes fluctuations in the period of . However, due to the cause of their occurrence, these error and fluctuation components provide accurate information on the number of rotations for each rotation of the wire 3c or for each rotation of the magnet 3b, and in FIG. tS+j! Yut
tl1=t,+4 holds, and too t. Ut1■ is established. Therefore, the optimal method for calculating vehicle speed accurately and with the most responsiveness is tIo. tlI+' I! Calculate the vehicle speed from its reciprocal.

Alternatively, store t1, t2, t3, and t4 in memory, calculate the average value of the four values, and calculate the vehicle speed from the average value. Next is t! Find the four average values of , t, t4, and t, and calculate the vehicle speed from the average value. In this way, the moving average values in the tlO interval, then the tl1 interval, and then the t+z interval are successively calculated.
This determines the vehicle speed. In this way, it is possible to calculate and judge vehicle speed accurately and with good responsiveness.
For such averaging processing and calculations, a microcomputer is used as the control device 1, and each period t,...t,, is counted by a timer of the microcomputer for each input of pulse energy, and the memory of the microcomputer is used. This can be easily realized by storing each cycle t1...1n. Next, to find the acceleration/deceleration of the vehicle speed between points a and b shown in FIG. 2, the vehicle speed at point a, vl. oc1/tI0 and
The vehicle speed at point b can be easily calculated from y ,,oc l / l ,4 and point a. Furthermore, when the vehicle speed increases, points d and e can also be calculated, for example. Also, as the vehicle speed increases, the number of pulses increases, so T
, >T, the calculation interval can be shortened. When detecting a sudden acceleration/deceleration in which the acceleration/deceleration calculated as described above exceeds a predetermined value and controlling the characteristics of the suspension, the following problems occur. In other words, although the acceleration and deceleration of the vehicle body can be calculated accurately using the above calculation, this vehicle speed pulse is 4 times per rotation of the wheel.
Since only pulses are generated, especially at low vehicle speeds, unless the above T is made long, the dt accuracy of the ↓ stem calculation will be poor. Conversely, T is 1 due to the responsiveness requirements of suspension control.
It cannot be made longer than about 0 (1 + s to 200 + s). On the other hand, if T is kept short, there is a drawback that the calculation accuracy of ±ヱ is not accurate. Also, as the speed increases, the number of pulses increases. However, the speedometer cable vibrates in response to the vibration of the vehicle body as the vehicle travels, causing fluctuations in the vehicle speed pulse, and the G
There is a drawback that there is a difference in the calculated value of (acceleration).

In this way, the performance error and responsiveness have contradictory properties, so it has been difficult to satisfy both simultaneously. Therefore, this invention solved the problem as follows. That is,
During T when acceleration/deceleration is being measured, each time a vehicle speed pulse is input to the control device 1 from the reed switch 3a of the vehicle speed sensor 3, the calculated average vehicle speed is compared to the average vehicle speed calculated one pulse before. The comparison is made to determine whether the state is accelerating or decelerating. If there is a change from acceleration to deceleration or from deceleration to acceleration, measurement of acceleration/deceleration is stopped at that point, and the current acceleration/deceleration is Disables the operation. Set a new measurement time T from the point when acceleration/deceleration is switched, start measuring acceleration/deceleration, and check if the vehicle is constantly accelerating during T.
Alternatively, calculation of acceleration/deceleration is performed for the first time when the vehicle is decelerating. By doing this, it is possible to prevent false detection of acceleration/deceleration due to fluctuations in the vehicle speed pulse caused by various factors, and it is possible to start measurement of acceleration/deceleration from the point at which sudden acceleration/deceleration actually starts. This provides a vehicle acceleration/deceleration detection device that does not impair responsiveness.

Accelerating. Deceleration may be determined based on the average vehicle speed, or may be determined by comparing the latest vehicle speed pulse cycle with the vehicle speed pulse cycle N pulses before.

FIG. 3 is a flowchart showing the flow of operations according to an embodiment of the present invention. First, starting from the start 30,
In step 31, it is checked whether a vehicle speed pulse is input from the reed switch 3a of the vehicle speed sensor 3 to the control device l. If there is no vehicle speed pulse, the process waits in step 31 until a vehicle speed pulse is input. This is because the vehicle speed calculated based on the latest vehicle speed pulse input is used to calculate the addition/subtraction.

When the vehicle speed pulse is input to the control device 1 in step 3l, the process proceeds to the step controller 32, sets acceleration/deceleration measurement time T, and starts measurement of acceleration/deceleration.

This measurement time T may be variable depending on the vehicle speed in order to achieve both accuracy and responsiveness of acceleration/deceleration detection. In step 33, the cycle of the latest one pulse of the vehicle-related sensor is measured, and in step 34, the vehicle-related pulse cycle measured in step 33 is replaced with the cycle of N pulses before and stored. By doing this, the vehicle speed pulse cycle for the latest N pulses is always stored. In step 35, the cycles of the latest N pulses are averaged to calculate the average vehicle speed.

In step 36, it is determined whether or not measurement of acceleration/deceleration has just started. If measurement has just started, the process advances to step 37, and the average vehicle calculated this time is stored. This memorized average vehicle speed becomes the initial speed v0 when calculating acceleration/deceleration. If it is determined in step 36 that acceleration/deceleration is already being measured, the process advances to step 38. In this step 38, the average vehicle speed calculated this time and 1
The average vehicle speed calculated before the pulse is compared to determine whether the vehicle is accelerating or decelerating. As a result of this comparison, if it is acceleration this time, the process proceeds to step 38a, where it is memorized that it is acceleration this time, and the process proceeds to step 39. In this step 39, it is determined whether the previous time was acceleration or deceleration, and if the previous time was also acceleration, step 4
1, and if the previous time was deceleration, it is determined that the acceleration/deceleration has switched from deceleration to acceleration, and the process returns to step 32, where the measurement of acceleration/deceleration is restarted from the beginning. When it is determined in step 38 that deceleration is occurring, step 38
Proceed to step b, remembering that this time it is deceleration, and step 4
Go to 0. In step 40, it is determined whether the previous time was acceleration or deceleration, and if the previous time was deceleration, step 4l is performed.
If the previous time was acceleration, it is determined that the acceleration/deceleration has switched from acceleration to deceleration, and the process returns to step 32 to start measuring the acceleration/deceleration from the beginning. In the flowchart of Fig. 3, by adding the determinations from Step 38 to Step 40, which are surrounded by dotted lines, false detection of acceleration/deceleration due to inaccurate vehicle speed pulses due to factors such as uneven rotation of the vehicle speed sensor cable can be prevented. In addition, when the vehicle actually accelerates or decelerates, measurement of acceleration and deceleration can be started without impairing responsiveness. In step 41, it is determined whether the measurement time T has elapsed since the start of acceleration/deceleration measurement, and if the time T has not elapsed since the start of measurement, step 42
Step 3 waits for the next vehicle speed pulse input, and if a vehicle speed pulse is input, returns to step 33 and calculates the average vehicle speed anew. If the measurement time T has passed in the step 41, the process advances to step 43, and the last calculated average vehicle speed v,
Then, the acceleration/deceleration is calculated as (T) from the initial velocity v0 and time T that were stored at the beginning of the measurement.

It is assumed that the timer that counts the measurement time T is decremented at regular intervals by an interrupt routine (not shown) and reset to 0. Also, at very low vehicle speeds, it takes too much time to calculate the acceleration/deceleration, so in the region below a predetermined vehicle speed,
It is possible to cancel calculation of acceleration/deceleration and omit unnecessary determination.

〔Effect of the invention〕

As described above, according to the present invention, while measuring the acceleration/deceleration of a vehicle, it is always determined whether the vehicle is accelerating or decelerating, and when acceleration continues for a certain period of time or deceleration continues for m, the acceleration/deceleration is calculated. As a result, it is possible to satisfy the conflicting demands of improving accuracy and increasing responsiveness, which are caused by the inaccuracy of the vehicle speed pulse signal due to factors such as uneven rotation of the vehicle speed sensor cable.

In addition, responsiveness can be further improved by switching the acceleration/deceleration calculation cycle depending on the vehicle speed and shortening the calculation cycle at higher speeds.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a suspension device incorporating a vehicle acceleration detection device according to an embodiment of the present invention, FIG. 2 is an output waveform diagram of a vehicle speed sensor in the embodiment, and FIG. 3 shows the operation of the embodiment. It is a flow chart for explanation. 1...Control device, 2...Brake switch, 3...
-Vehicle speed sensor, 4...Vehicle body, 5...Shock absorber, 7...Wheel, 9...Air spring, 14...Vehicle height sensor. Note that the same reference numerals in the figures indicate the same or equivalent parts.

Claims (1)

[Claims] A vehicle speed sensor that generates a pulse signal proportional to the wheel speed of the vehicle, and a vehicle speed sensor that measures the latest N first pulse periods of the pulse signal and replaces these N pulse periods with data of the previous pulse period. a means for storing, and a means for calculating a first average vehicle speed from the latest N first pulse cycles stored by the means, and a vehicle speed sensor for calculating a first average vehicle speed after a predetermined time T_0 from the generation of the first pulse cycle. A second average vehicle speed is calculated from the second pulse period of the pulse generated from , and the time T_1 from the first pulse period to the second pulse period is measured to calculate (V_2-V_1)/T.
An acceleration/deceleration calculation device for a vehicle, comprising means for determining the acceleration/deceleration of the vehicle from the calculated value of _1.