JPH04204059A - Angular acceleration and angular velocity detection device - Google Patents

Abstract

PURPOSE:To enable influence due to disturbance to be reduced and measurement accuracy of an angular velocity and angular acceleration to be improved by cutting off a specific frequency of an output of two acceleration sensors which are placed on the same plane using a low-pass filter and obtaining the difference. CONSTITUTION:Acceleration sensors 3 and 4 are separated left and right by L/2 from a weight center 10 on a plane which is in parallel to a floor surface of an automobile and are fixed at measurement points 1 and 2. When an angular acceleration of omegaalpha is applied to the automobile, acceleration which is generated in opposite direction at the measurement points 1 and 2 is detected and the output is fed to low-pass filters 5 and 6, where noise frequencies which cause disturbances are cut off and the difference is obtained by a differential equipment 11 and a yaw angle acceleration omega'alpha which is obtained by multiplying a constant 1/L is integrated by an integrator 9, thus obtaining a yaw angular velocity omega'. Therefore, disturbances at the measurement points 1 and 2 can be reduced and measurement error can be restricted.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an angular acceleration detection device using an acceleration sensor, and a filtering method in an angular velocity detection device that integrates the angular acceleration signal.

[Conventional technology]

Conventionally, angular velocity is one of the physical quantities used to measure the state of one-rotation motion, and is used in optical fiber gyros and vibration gyros.

Gas rate sensors and the like were often used.

On the other hand, in the method described in JP-A No. 62-70766, acceleration sensors are fixed at two locations on a moving body so that their detection axes are parallel, and the angular acceleration of the moving body is calculated from the difference in output between the sensors. It was something to calculate.

Further, if it is desired to obtain a physical quantity in the dimension of angular velocity, a method is disclosed in which the angular velocity obtained as described above is integrated and used.

[Problem to be solved by the invention]

The above-mentioned conventional technology detects the rotational angular velocity of a vehicle, and the angular acceleration is determined from the difference between acceleration sensors fixed to two locations on the vehicle, and the angular velocity is determined by integrating the obtained angular acceleration.

However, especially in a moving object such as a vehicle, acceleration noise components due to engine vibration and minute irregularities on the road surface are likely to enter, which not only causes detection errors in angular acceleration, but also causes even larger errors in the angular velocity after integration. There was a problem.

An object of the present invention is to minimize errors in measuring angular velocity caused by external disturbances such as carrot vibrations and road surface irregularities, for example in automobiles.

[Means to solve the problem]

In order to achieve the above object, a low-pass filter is inserted somewhere in the signal line in order to reduce the influence of high-frequency noise of disturbance.

However, the low-pass filter is configured not to apply the angular velocity component after the integral processing, but to apply it to the acceleration dimension signal before performing the difference.

Further, the cutoff frequency of the low-pass filter is set higher than the frequency at which a moving body, for example, a car, can actually rotate, and lower than the frequency of noise that causes disturbance.

[Effect]

In the angular acceleration and angular velocity detection device including the filter as described above, even if a noise component of acceleration due to disturbance is mixed, it is possible to reduce the gain of the noise and prevent an increase in the integral error of angular velocity.

Furthermore, since the low-pass filter is inserted before the difference, even when inserting a low-pass filter with the same time constant, a greater error reduction effect can be obtained than when inserting it in the signal after integration.

In addition, the cutoff frequency of the low-pass filter is set higher than the frequency at which the car can actually rotate and lower than the noise frequency of the disturbance, so only the noise component is cut and the response of the measurement signal is not deteriorated.

〔Example〕

An embodiment of the present invention is shown in FIG. 1, a conventional example is shown in FIG. 2, and signals in each case are shown in FIG. 3. As can be seen from FIGS. 1 and 2, in this embodiment, an example of a moving body will be explained using an automobile.

Furthermore, in FIGS. 1 and 2, the angular velocity to be measured will be explained as a yaw angular velocity.

The acceleration sensors 3 and 4 are fixed to a plane parallel to the floor of the automobile. The fixed position is measurement point 1 or measurement point 2 in Figure 1.
, and are each one distance from the center of gravity 10 of the automobile to the left and right. The two acceleration sensors measure in the longitudinal direction of the vehicle.

When an angular acceleration of ω is applied to the automobile in the direction shown in the figure, acceleration occurs at measurement point 1 in the positive direction and at measurement point 2 in the negative direction. The magnitude of the generated acceleration can be expressed by the following equation.

G(ω)...Acceleration generated by ω (m/SJL・
・・・・・・Distance between measurement points 1 and 2 (m) (ω)・
...Yaw angular acceleration (rad/S'') The acceleration detected by each acceleration sensor actually includes the longitudinal acceleration GB at the center of gravity and the disturbance ν due to engine vibration and unevenness of the range surface. Therefore, it becomes as follows.

G-engine... Acceleration measured at measurement point 1 Gs... Longitudinal acceleration ν1 at the center of gravity point... Disturbance at measurement point 1 Also, at measurement point 2, only the sign of the second item is opposite, and the following It can be expressed as a formula.

Here, the measured G1. Using G2, the yaw angular acceleration ω
′ becomes the following formula.

In the above, it can be seen that the second term includes the error.

(4) If we take the correspondence shown in Figure 1 or Figure 2, G knee 02
is being calculated by the subtractor 11.

Transfer functions 7 and 8 are multiplied by one.

The yaw angular acceleration ω′ obtained in this way is input to the integrator 9.
By integrating with , the yaw angular velocity ω' is obtained.

Here, the differences between FIG. 1, which is an embodiment of the present invention, and FIG. 2, which is a conventional method, will be compared using the signals shown in FIG.

Assume that a pulse-like disturbance signal has entered measurement point 1. Figures 3a) and 3b) represent acceleration signals at measurement points 1 and 2. Each signal is converted into an electrical signal by the acceleration sensor 3.4, but the waveform remains the same as in FIGS. 3a) and 3b).

In the conventional method, the signals from the acceleration sensors 3 and 4 are directly differentiated and multiplied by a constant -, so the waveform of the negative yaw addition ω'201 becomes as shown in FIG. 3C).

On the other hand, in FIG. 1 showing an embodiment of the present invention, the pulse-like waveform is filtered by the filter 5, so the yaw angular acceleration 103 has a waveform as shown in FIG. The error is smaller than that of the previous method.

Furthermore, the results of integration to determine the yaw angular velocity are shown.

In the conventional method, since the yaw angular acceleration ω' 201 is integrated, the yaw angular velocity w' 202 becomes as shown in FIG. 3e).

Even if a filter 21 of the same size as the filter 5 is inserted, it will only result in the error ω as shown in Figure 3 f). remains unchanged.

On the other hand, in FIG. 1, which is an embodiment of the present invention, when the yaw angular acceleration ca' 103 is integrated by the integrator 9, the yaw angular velocity u' 104 becomes as shown in FIG. 3 g), which is different from the conventional method. The error is ω. can be made smaller.

The difference between C) and d), e) and g), or f) and g) in FIG. 3 is changed by the time constant T of the filters 5 and 6.

The filter's time constant is determined by the filter's cutoff frequency;

It is desirable to set the frequency higher than the frequency characteristics related to the rotational motion of the automobile and lower than the noise frequency.

The above embodiment of the present invention has been described for the case of measuring the yaw angular velocity of an automobile, but similarly, the roll angular velocity,
It can also be applied to pitch angular velocity.

Pitch angular acceleration and pitch angular velocity can be detected by a combination of 401, 402 or 403, 404 in FIG. 4a).

Also, 405, 406 or 407°40 in Figure 4 b)
Yaw angular acceleration and yaw angular velocity can be detected with the combination of 8.

Similarly, 409.41-0 or 410.C in Figure 4C).
The roll angular acceleration and roll angular velocity can be detected by the combination of 412.

Next, FIG. 5 shows the hardware configuration of this embodiment, including acceleration sensors 3, 4, hard filter 501,
502, A/D converter 503, CPU504, ROM5
05, RAM506.

CPU504 and RAM506. RAM506. ! : constitutes a calculator. The calculator can be used to calculate, for example, an automobile's ABS (
It is also possible to use a computer for a control device for another purpose, such as an anti-skid brake system) or a navigation device for ships or aircraft.

The CPU 504 performs arithmetic processing, and software and O8 for this purpose are stored in the ROM 505, and the RAM 506 has the role of storing work data.

Here, the CPU 504 may be a DSP (digital signal processor).

In addition, an A/D converter 503, a hard filter 501 .
502, the hardware is constituted by the acceleration sensors 3 and 4, but if the low-pass filter is created by software, the hard filters 501 and 502 may not be provided.

〔Effect of the invention〕

Since the present invention is configured as described above, it produces the effects described below.

By filtering the acceleration signals fixed at two locations on the moving body separately, taking the difference, and performing integration processing, it is possible to suppress errors when disturbance noise is mixed in.

[Brief explanation of the drawing]

Figure 1 is a basic block diagram of the present invention, Figure 2 is a basic block diagram of a conventional example, Figure 3 is a diagram showing the signals in the block diagram, and Figure 4 shows how the acceleration sensor is mounted on the vehicle body. The figure shown in FIG. 5 is a hardware block diagram of one application example of the present invention. 3.4... Acceleration sensor, 5,6... Filter (low ^ ^ ^
＾Pe Hata Ri
fable o (:l
.

Claims (6)

[Claims] 1. first and second acceleration sensors arranged at a distance on one plane of a moving body and arranged so that respective acceleration detection methods are parallel; and the first and second acceleration sensors. In the rotational motion detecting device described above, the detection device comprises means for determining a difference between the outputs of , determining a rotational angular acceleration around an axis perpendicular to the one plane from the difference, and further integrating the rotational angular acceleration to determine the rotational angular velocity. An apparatus for detecting angular acceleration and angular velocity, characterized in that the process of performing a difference between two signals is performed after each of the two signals is filtered by a low-pass filter. 2. 2. An apparatus for detecting angular acceleration and angular velocity of an automobile according to claim 1, wherein the moving body is an automobile, and the angular velocities to be determined are yaw angular velocity, roll angular velocity, and pitch angular velocity. 3. 2. An angular acceleration and angular velocity detecting device, wherein the low-pass filter according to claim 1 is constituted by a circuit network consisting of a resistor and a capacitor. 4. 2. An angular acceleration and angular velocity detection device according to claim 1, wherein the low-pass filter is a digital filter using sampled and held signals. 5. The detected angular velocity of the angular acceleration and angular velocity detecting device of the automobile according to claim 2 is taken in, a predetermined target angular velocity is given, and the rotational angular velocity (yaw angular velocity, roll angular velocity, pitch) of the vehicle body is adjusted so that the detected angular velocity becomes the target angular velocity. angular velocity)
A control device for an automobile, characterized in that it performs negative feedback control. 6. 2. An apparatus for detecting angular acceleration and angular velocity of a moving body according to claim 1, wherein the time constant (or cutoff frequency) of the low-pass filter is determined and set from frequency characteristics related to rotational motion of the moving body.