JPH11326356A - Speed operation apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To correctly calculate a vehicle speed in real time. SOLUTION: A counter 6 counts pulse signals 5 of a frequency proportional to a speed of a wheel 1 which are output from a pulse generation means (2, 4), and outputs a vehicle speed pulse signal for every predetermined count of pulse signals. A vehicle speed pulse speed operation means 11 calculates the present vehicle speed pulse speed vpn on the basis of a vehicle speed pulse time tn of the counter from a previous vehicle speed pulse signal timing τn-1 to the present vehicle speed pulse signal timing τn. An acceleration operation means 13 calculates an acceleration an from a previous vehicle speed pulse speed vpn-1, the vehicle speed pulse speed vpn and the vehicle speed pulse time tn. A correction speed operation means 14, with the use of the present vehicle speed pulse speed vpn, the acceleration an and the vehicle speed pulse time tn, calculates a correction vehicle speed pulse speed v(t) at a time point after (t) hours from a time point when the present vehicle speed pulse speed vpn is obtained, and obtains a speed closer to an actual vehicle speed (v) by calculations.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle speed calculation device.

[0002]

2. Description of the Related Art Hitherto, a speed calculation device employed for obtaining speed data of a vehicle has been as follows.

As shown in FIG. 5, a sine wave signal 3 having a frequency proportional to the rotational speed of a wheel is extracted by a rotary encoder 2 mounted on the axle of the wheel 1, and the sine wave signal 3 is converted into a rectangular wave by a signal converter 4. The signal is converted into a signal 5 and output. The counter 6 counts the rectangular wave signal 5 by a predetermined number, for example, eight cycles, and outputs a vehicle speed pulse signal 7 to the vehicle speed pulse speed calculator 8 every time the counting is completed. When receiving the vehicle speed pulse signal 7, the vehicle speed pulse speed calculation unit 8 looks at the elapsed time tn from the time when the vehicle speed pulse signal 7 was previously received, and uses this as a vehicle speed pulse signal to calculate the vehicle speed by the following equation (5). Calculate the pulse speed vpn.

[0004]

(Equation 5) Here, n is an arbitrary integer, which means that this time is the n-th measurement (the same applies to the following and description). Β is a constant determined by the vehicle type.

The vehicle speed pulse speed vpn thus calculated is
The final vehicle running speed is recorded in the memory for each calculation, and output as a graph if necessary, or printed out as speed data, for example, to be used as strict speed data at the time of a collision test. .

[0006] This point will be described in more detail. As shown in FIG. 6, the sine wave signal 3 output from the rotary encoder 2
On the other hand, the signal converter 4 outputs the rectangular wave signal 5 and outputs the vehicle speed pulse signal 7 when the counter 6 counts a predetermined number of pulses, here eight pulses.

The vehicle speed pulse speed calculation unit 8 measures the elapsed time tn from the previous rising timing τn-1 of the vehicle speed pulse signal 7 to the rising timing τn of the current vehicle speed pulse signal 7, and calculates the above equation (5). The current speed v (t) is obtained as the vehicle speed pulse speed vpn by the equation.

[0008]

However, such a conventional speed calculation device has the following problems. As shown in FIGS. 7 and 8, the current vehicle speed pulse speed vp
In order to calculate n, the current vehicle speed pulse speed vpn is newly calculated from the timing τn−1 at which the previous vehicle speed pulse signal was obtained.
It is necessary to count a predetermined number of square wave pulses by the timing τn at which the calculation of the following equation is started. This period tn is strictly a past event, and during this period, the actual vehicle speed v becomes vn
It changes gradually from -1 to vn. Therefore, the current calculated vehicle speed pulse speed vpn is the average speed during this period tn.

Therefore, if the actual vehicle speed is in an accelerating state, an error of δ occurs between the actual vehicle speed vn and the vehicle speed pulse speed vpn as shown in FIG.

The present invention has been made in view of such conventional problems, and has as its object to provide a speed calculation device capable of obtaining a calculation speed very close to the actual vehicle speed.

[0011]

According to a first aspect of the present invention, there is provided a speed calculating apparatus for outputting a pulse signal having a frequency proportional to a rotation speed of a wheel, and a pulse signal output from the pulse generating means. A counter that outputs a vehicle speed pulse signal every time a predetermined number is counted, and a counter (e.g., a vehicle speed pulse time) that elapses from a timing at which the counter previously output a vehicle speed pulse signal to a timing at which a new vehicle speed pulse signal is output. A vehicle speed pulse speed calculating means for obtaining a new vehicle speed pulse speed, a previous vehicle speed pulse speed obtained by the previous calculation by the vehicle speed pulse speed calculating device, the newly obtained current vehicle speed pulse speed, and the vehicle speed pulse time; Acceleration calculation means for obtaining an acceleration from the vehicle, and a correction term using the acceleration obtained by the acceleration calculation means and the current vehicle speed pulse time. Determined, in which a correction speed calculating means for obtaining the correction vehicle speed pulse rate by adding the vehicle speed pulse rate of the time.

According to a second aspect of the present invention, in the speed calculating device of the first aspect, the vehicle speed pulse speed calculating means outputs a timing (τn-1) at which the counter outputs a previous (n-1st) vehicle speed pulse signal. ) From this time (n
Timing (τ) at which the vehicle speed pulse signal is output
n), a new current vehicle speed pulse speed (referred to as vpn) is calculated based on the elapsed time (referred to as vehicle speed pulse time tn).

(Equation 6) The vehicle speed pulse speed vpn-1 obtained by the vehicle speed pulse speed calculation device in the previous calculation (n-1 time) and the current vehicle speed pulse speed
From vpn and the vehicle speed pulse time tn, the acceleration (αn) is calculated as follows:

(Equation 7) And the correction speed calculating means calculates the current vehicle speed pulse speed vpn obtained by the vehicle speed pulse speed calculating means.
Using the acceleration αn obtained by the acceleration calculation means and the current vehicle speed pulse time tn, the corrected vehicle speed pulse speed (v (v ( t)),

(Equation 8) It is what is sought.

According to the first and second aspects of the present invention, the counter counts a pulse signal having a frequency proportional to the rotation speed of the wheel, which is output from the pulse generation means. Output. Therefore, the vehicle speed pulse speed calculation means determines that this counter
Timing τn at which the (-1st) vehicle speed pulse signal was output
Based on the vehicle speed pulse time tn from −1 to the timing (τn) at which the current (n-th) vehicle speed pulse signal is newly output, the current vehicle speed pulse speed vpn is calculated by Expression 6. Further, the acceleration calculation means calculates the acceleration αn from the previous vehicle speed pulse speed vpn−1, the current vehicle speed pulse speed vpn, and the vehicle speed pulse time tn according to equation (7).

The correction speed calculating means uses the current vehicle speed pulse speed vpn, the acceleration αn, and the vehicle speed pulse time tn to obtain the current vehicle speed pulse speed vpn. Vehicle speed pulse speed v (t) (=
v′n) is calculated by Expression 8.

Thus, the current vehicle speed pulse speed vpn
The change of the vehicle speed between the previous vehicle speed pulse speed vpn-1 and the current vehicle speed pulse speed vpn, that is, correction taking into account the acceleration αn, as the vehicle speed v (t) at the time point t after the calculation of The vehicle speed pulse speed v'n is obtained, and a speed closer to the actual vehicle speed v than before is obtained by calculation.

According to a third aspect of the present invention, in the speed calculation device of the first or second aspect, the secondary correction vehicle speed pulse speed at a point in time after a certain time has elapsed since the present vehicle speed pulse speed was obtained is calculated by the acceleration calculation device. And a secondary correction speed calculating means for obtaining a secondary corrected vehicle speed pulse speed by obtaining the corrected vehicle speed pulse speed by adding the corrected vehicle speed pulse speed obtained by the corrected speed calculating means by linear approximation using the acceleration obtained by the calculating means. .

According to a fourth aspect of the present invention, in the speed calculation device according to the third aspect, the secondary correction speed calculation means determines the corrected vehicle speed pulse speed v (t) obtained by the correction speed calculation means. The secondary corrected vehicle speed pulse speed (v "(t)) at time t after the current vehicle speed pulse speed vpn is obtained,

(Equation 9) It is what is sought.

According to the third and fourth aspects of the present invention, the current vehicle speed is compared with the corrected vehicle speed pulse speed v (t) obtained by the corrected speed calculating means in the speed calculating device according to the first or second aspect of the present invention. The secondary corrected vehicle speed pulse speed v "(t) at the point in time t has elapsed since the pulse speed vpn was obtained is obtained by using equation (9).

Thus, the approximate vehicle speed at the current time t is secondarily corrected by linear approximation using the acceleration αn with respect to the corrected vehicle speed pulse speed v (t) (= v'n) obtained by the corrected speed calculation means. A vehicle speed pulse speed v "(t) is obtained, and a speed closer to the actual vehicle speed v is obtained by calculation.

[0020]

As described above, according to the first and second aspects of the present invention, the vehicle speed v (t) at the time t after the current vehicle speed pulse speed is calculated is calculated as the vehicle speed v (t). It is possible to obtain a corrected vehicle speed pulse speed in consideration of the acceleration between the current vehicle speed pulse speed and the actual vehicle speed v.
Is calculated by calculation.

According to the third and fourth aspects of the present invention, a first aspect is provided.
Or the corrected vehicle speed pulse speed v obtained by the second speed calculation device.
(t), the approximate vehicle speed at the current time point t can be obtained as a secondary corrected vehicle speed pulse speed v "(t) by linear approximation using acceleration, and a speed closer to the actual vehicle speed v is calculated. You can ask.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 shows the configuration of the speed calculation device according to the first embodiment of the present invention. The speed calculating device according to the first embodiment includes a rotary encoder 2 attached to an axle of a wheel 1 and outputting a sine wave signal 3 having a frequency proportional to the rotation speed of the rotary encoder 2. A signal converter 4 for converting the sine wave signal 3 of the encoder 2 into a rectangular pulse signal 5; counting the number of pulses of the rectangular pulse signal 5 output from the signal converter 4; The counter 6 outputs a vehicle speed pulse signal 7 each time the counting is completed.

The speed calculating apparatus according to the present embodiment further calculates a new vehicle speed pulse speed based on the elapsed time from the timing when the counter 6 outputs the previous vehicle speed pulse signal 7 to the time when the counter 6 outputs a new vehicle speed pulse signal. A vehicle speed pulse speed calculating unit 11 to calculate, a storage unit 12 for storing each vehicle speed pulse speed calculated by the vehicle speed pulse speed calculating unit 11, and an acceleration based on the previous vehicle speed pulse speed and the newly calculated vehicle speed pulse speed. Acceleration calculator 1 to calculate
3, and a corrected vehicle speed pulse speed calculator 14 that calculates and outputs a corrected vehicle speed pulse speed based on the vehicle speed pulse speed calculated by the vehicle speed pulse speed calculator 11 and the acceleration calculated by the acceleration calculator 13.

Next, the operation of the speed calculating device having the above configuration will be described. As shown in FIG. 6, the rotary encoder 2 outputs a sine wave signal 3 having a frequency proportional to the rotation speed of the wheel 1, as in the conventional example. And output. The counter 6 counts the rectangular wave pulse signal 5 by a predetermined number, for example, eight cycles, and outputs a vehicle speed pulse signal 7 to the vehicle speed pulse speed calculator 8 every time counting is completed.

As shown in FIG. 8, the vehicle speed pulse speed calculator 8 detects the rising of the vehicle speed pulse signal 7, and at the timing τn, the rising of the vehicle speed pulse signal 7 last time (that is, the (n-1) th time). At which τ is detected
The elapsed time tn (= τn−τn−1) from −1 is obtained, and this is set as the vehicle speed pulse time. 12 is stored. Therefore, in the storage unit 12,..., Vpn−2, vpn−1, vpn, vpn + 1, vp
n + 2,... are stored.

Each time the vehicle speed pulse speed calculation unit 11 newly calculates the current vehicle speed pulse speed vpn, the acceleration calculation unit 13 calculates the previous vehicle speed pulse speed vpn-1 stored in the storage unit 12 and the current vehicle speed pulse speed vpn. The acceleration αn is calculated from the speed vpn and the vehicle speed pulse time tn according to the above equation (7).

Then, the corrected vehicle speed pulse speed calculator 14 calculates
Using the current vehicle speed pulse speed vpn, acceleration αn, and vehicle speed pulse time tn, the current vehicle speed pulse speed vp
The calculation speed v (t) at the current point in time t has elapsed since n was obtained
And calculates and outputs the speed-corrected vehicle speed pulse speed v'n according to the above equation (8).

The current speed v (t) (= v ') thus output
n) is used, for example, to determine whether the speed should activate the pedestrian protection device, whether the ABS needs to operate, etc., or can be extracted and graphed by a speed measuring device, and a collision test can be performed. Or as the speed at the time of collision.

As a result, in the speed calculating device according to the first embodiment, the calculated speed can be made closer to the actual speed as compared with the conventional one as described below. In FIG. 2, the actual vehicle speed is shown by a curve A. Here, a state in which the vehicle is in an acceleration state is shown. .., Vpn-1, vpn, vpn + 1,... By the conventional speed calculation device are indicated by chain lines, and the vehicle speed v (t) according to the present embodiment is indicated by a stepwise solid line. Also, on the actual vehicle speed curve A,.
vn, vn + 1,... indicate the actual vehicle speed at the rising timing of each vehicle speed pulse..., τn-1, τn, τn + 1,. In the case of the present embodiment, at the timing τn at which the current vehicle speed pulse speed vpn is calculated, a correction amount (= αn · tn / 2, αn · tn / 2, Since the corrected vehicle speed pulse speed v'n that takes into account the portion indicated by the circle in FIG. 2) is obtained, a calculated speed closer to the actual vehicle speed is obtained.

In the present embodiment, after this, until the next rising timing τn + 1 of the vehicle speed pulse signal,
As the vehicle speed v (t) at the time when t time has elapsed from the rising timing τn of the current vehicle speed pulse, v (t) = v′n
(Constant) is used. This is the same as the conventional one.

Next, a second embodiment of the speed calculating device according to the present invention will be described with reference to FIGS. The feature of the second embodiment is that the corrected vehicle speed pulse speed calculation unit 1 is different from the configuration of the speed calculation device of the first embodiment shown in FIG.
4 in that a secondary correction vehicle speed pulse speed calculation unit 15 for performing a secondary correction on the correction vehicle speed pulse speed v′n calculated in 4 is provided. Other configurations are the same as those of the first embodiment shown in FIG. 1, and the same components are denoted by the same reference numerals and detailed description thereof will be omitted.

In the speed calculating device according to the second embodiment, similarly to the first embodiment, the corrected vehicle speed pulse speed calculating unit 14
The secondary corrected vehicle speed pulse speed calculator 15 performs the secondary correction of the above equation (9) on the corrected vehicle speed pulse speed v′n calculated by the above equation, and the result v ″ (t) is calculated as the final calculated speed. v (t), that is, the corrected vehicle speed pulse speed v'n which is the final output speed of the speed calculation device of the first embodiment shown in FIGS. The vehicle speed pulse speed v (t) at the present time after the elapse of the time t from the obtained timing τn is calculated and output by the equation (9).

As a result, as shown in FIG. 4, the current vehicle speed pulse speed vpn at the timing τn obtained by the conventional method is compared with the acceleration αn similar to that of the first embodiment.
Primary correction (= αn · tn / 2) based on the vehicle speed pulse speed vp by linear approximation using acceleration αn
Since the speed change from the timing τn at which n was obtained to the current time when t time has elapsed is obtained by the secondary correction (= αn · t), the calculated speed closer to the actual vehicle speed v at the current time t can be obtained. is there.

In the above two embodiments,
The rising timing of the vehicle speed pulse signal 7 output from the counter 6 is not particularly limited to eight periods of the rectangular pulse signal 5, but can be appropriately determined according to the calculation speed characteristics of the CPU employed by the device. It is. Also,
Instead of the rising timing of the vehicle speed pulse signal 7, a falling timing may be employed.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a first embodiment of the present invention.

FIG. 2 is an explanatory diagram of a speed calculation process according to the embodiment.

FIG. 3 is a block diagram showing a configuration according to a second embodiment of the present invention.

FIG. 4 is an explanatory diagram of a speed calculation process according to the embodiment.

FIG. 5 is a block diagram showing a configuration of a conventional example.

FIG. 6 is a waveform diagram showing output waveforms of a rotary encoder, a signal converter, and a counter in a conventional example.

FIG. 7 is an explanatory diagram showing a relationship among a vehicle speed pulse signal, a vehicle speed pulse time, and an acceleration in a conventional example.

FIG. 8 is an explanatory diagram of speed calculation processing of a conventional example.

[Explanation of symbols]

 Reference Signs List 1 wheel 2 rotary encoder 3 sine wave signal 4 signal converter 5 rectangular pulse signal 6 counter 7 vehicle speed pulse signal 11 vehicle speed pulse speed calculation unit 12 storage unit 13 acceleration calculation unit 14 correction vehicle speed pulse speed calculation unit 15 secondary correction vehicle speed pulse speed Arithmetic unit

Claims (4)

[Claims] 1. A pulse generating means for outputting a pulse signal having a frequency proportional to a rotation speed of a wheel, a counter for outputting a vehicle speed pulse signal every time a predetermined number of pulse signals output from the pulse generating means are counted, Vehicle speed pulse speed calculating means for obtaining a new vehicle speed pulse speed based on an elapsed time (vehicle speed pulse time) from a timing at which the counter previously output a vehicle speed pulse signal to a timing at which a new vehicle speed pulse signal is output; Acceleration calculation means for obtaining acceleration from the previous vehicle speed pulse speed obtained by the previous calculation by the vehicle speed pulse speed calculation means, the newly obtained current vehicle speed pulse speed, and the vehicle speed pulse time; A correction term is obtained using the acceleration and the current vehicle speed pulse time, and is added to the current vehicle speed pulse speed to make a correction. Velocity calculating device comprising a correction rate calculating means for calculating a vehicle speed pulse rate. 2. The vehicle speed pulse speed calculating means according to claim 1, wherein said counter outputs a new (n-th) vehicle speed from a timing (τn−1) at which said counter output a previous (n−1-th) vehicle speed pulse signal. A new current vehicle speed pulse speed (vpn) is determined based on the elapsed time (vehicle speed pulse time tn) up to the timing (τn) at which the pulse signal was output.
) Is given by The acceleration calculating means calculates the previous vehicle speed pulse speed vpn-1 obtained by the vehicle speed pulse speed calculating means in the previous calculation (n-1 times), the current vehicle speed pulse speed vpn, and the vehicle speed pulse. From the time tn, the acceleration (referred to as αn) is given by: The correction speed calculation means uses the current vehicle speed pulse speed vpn obtained by the vehicle speed pulse speed calculation means, the acceleration αn obtained by the acceleration calculation means, and the current vehicle speed pulse time tn. And the current vehicle speed pulse speed vp
The corrected vehicle speed pulse speed (referred to as v (t)) at the time when t time has elapsed since n was obtained is given by: The speed calculation device according to claim 1, wherein the speed calculation device obtains the speed. 3. A secondary corrected vehicle speed pulse speed at a point in time when a certain time has elapsed since the present vehicle speed pulse speed was obtained,
And a secondary correction speed calculating means for obtaining a secondary corrected vehicle speed pulse speed by adding the corrected vehicle speed pulse speed obtained by the corrected speed calculating means by linear approximation using the acceleration obtained by the acceleration calculating means. The speed calculation device according to claim 1. 4. The secondary correction speed calculating means obtains the current vehicle speed pulse speed vpn with respect to the corrected vehicle speed pulse speed v (t) obtained by the correction speed calculation means, and t time has elapsed. The secondary corrected vehicle speed pulse speed at the time (referred to as v "(t)) is given by: The speed calculation device according to claim 3, wherein the speed calculation device obtains the speed.