JPH0526893A - Detecting device for acceleration - Google Patents

Abstract

PURPOSE:To make the acceleration measurement of an object proper, by oscillating an oscillating means compulsorily by an exciting means and carrying out the detection of the acceleration by the change of an oscillating state. CONSTITUTION:An acceleration detection device 10 is provided with a U-base 12, an oscillator 14 as an oscillating means, of which the one end is fixed to the base 12, an exciting means 16 to oscillate the oscillator 14, and a displacement detecting means 18 consisting of a photoelectric encoder. The unknown acceleration can be known by oscillating the mass M of the oscillator 14 compulsorily with F sin wt by the exciting means 16 and by detecting a phased delay angle phi by the displacement detecting means 18 because the phase delay angle phichanges considerably when the acceleration operates in the X-axis direction. If a saw tooth wave is synchronized to sin wt to be formed and t1-t0 or t3-t2 is found, the phase delay phi can be found. Thus the detection of the acceleration can correctly be carried out with the simple constitution.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an acceleration detecting device, and more particularly to an acceleration detecting device using a forced vibration mechanism.

[0002]

2. Description of the Related Art In recent years, an automobile or the like is provided with an acceleration detecting device for maintaining proper movement of the automobile and for preventing slips when entering a curve at high speed or during rapid acceleration or sudden deceleration. Such an acceleration detecting device generally detects acceleration from the moving direction and moving amount of the elastically supported weight.

[0003]

However, in the above-mentioned conventional acceleration detecting device, there are cases where the weight shakes when applying or releasing acceleration, and accurate acceleration cannot be continuously detected. The present invention has been made in view of the above-mentioned problems of the prior art, and an object thereof is to provide an acceleration detection device that can always properly measure the acceleration of an object.

[0004]

In order to achieve the above-mentioned object, an acceleration detecting device according to the present application comprises a vibrating means extending substantially in an acceleration applying direction, and vibrating the vibrating means in a direction orthogonal to the extending direction. A vibrating means for applying a force, a displacement detecting means for detecting a displacement of the vibrating means in a vibration direction,
It is characterized by having.

[0005]

In the acceleration detecting device according to the present invention, as described above, the vibrating means is forcibly vibrated by the vibrating means and the acceleration is detected based on the change of the vibration state. Therefore, the acceleration is applied or released. Sometimes the response is extremely quick.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows a principle view of the present invention. FIG. 1A is a side view and FIG. 1B is a top view.

In FIG. 1, the acceleration detecting device 10 comprises a vibrating means 14 having one end fixed to the base 12 and the other end having a mass M, and a vibrating means 16 for forcibly vibrating the vibrating means 14 at Fsinωt. .. Then, the vibrating means 16 continuously applies a force to the tip portion of the vibrating means 14 to vibrate in the Y-axis direction in the drawing. In this state, the equation of motion in the Y-axis direction when acceleration α is applied in the X-axis direction in the figure is expressed by the following equation 1.

[Equation 1] Where C: damping coefficient E: Young's modulus (longitudinal elastic modulus) I: moment of inertia of leaf spring F: force

In the above expression 1, K is set as in the following expression 2.

[Equation 2] Then, the above expression 1 can be written as the following expression 3.

[Equation 3] From Equation 3, the damping factor ζ is expressed by Equation 4 below.

[Equation 4] The natural angular frequency ω _n is given by the following equation 5.

[0009]

[Equation 5] The phase delay (phase angle) φ is expressed by the following equation 6.

[Equation 6] The frequency ratio r is expressed by the following equation 7.

R = ω / ω _n where the natural angular frequency ω _n is X
It is a function of the axial acceleration α. Therefore, when the acceleration α = 0 in the X-axis direction, the equation 5 becomes the following equation 8.

[0010]

## EQU8 ## ω _n (α = 0) = (3EI / ML ³ ) ^1/2 Then, the angular frequency ω of the forced vibration is determined as in the following Expression 9.

## EQU9 ## ω = ω _n (α = 0) = (3EI / ML ³ ) ^1/2 As a result, the frequency ratio r can be rewritten as the following Equation 10.

[Equation 10] From the above equation 10, the frequency ratio r is a function of the acceleration α.
Further, from the above equation 6, the phase delay φ is a function of the frequency ratio r. Therefore, it is understood that the phase delay φ is a function of the acceleration α.

Normally, the damping factor ζ can be designed to be about ζ = 0.05 to 0.2. Therefore, when ζ = 0.05 and ζ = 0.1, the phase delay φ near the resonance point and the frequency ratio r The relationship is calculated as shown in FIG.

From the above equation 3, the steady-state amplitude y _p
Is expressed by the following equation 11.

[Mathematical formula-see original document] y _p = Asin (ωt-φ) where A is expressed by the following equation 12.

[Equation 12] Therefore, considering FIG. 2 and Equation 11, by setting ω = ω _n (α = 0), the unknown acceleration can be efficiently obtained by reading the phase delay φ when the unknown acceleration α works. You can

Next, a more specific first embodiment of the present invention will be described with reference to FIG. In addition, the same figure (A) is a left side view,
FIG. 3B is a top view. The acceleration detecting device 10 shown in the same drawing is a U-shaped base 12, a vibrator 14 as one of the vibrating means having one end fixed to the base 12, a vibrating means 16 for vibrating the vibrator 14, and a photoelectric encoder. And a displacement detecting means 18 formed of. The vibrator 14 is formed in a leaf spring shape, a cylinder 20 made of a prismatic ferromagnetic body is fitted to the free end of the vibrator 14, and a movable scale 22 is provided at the end of the vibrator 14.

The vibrating means 16 is composed of a rod-shaped core 24 and an excitation coil 26 wound around the rod-shaped core 24,
It is fixed to the base 12 via a bush 28. The tip of the rod-shaped core 24 is close to the flat surface portion of the ferromagnetic tube 20. Acceleration detection device 1 according to the present embodiment
0 is configured as described above, and its operation will be described below. First, the mass of the vibrator 14 including the cylinder 20 and the movable scale 22 provided at the tip M = 1 × 10 ⁻⁶ kg · sec ² / mm Young's modulus E = 1.2 × 10 ⁴ kg / mm ² Spring plate Thickness h = 0.2 mm Spring width b = 3 mm Spring length L = 42 mm, ω = ω _n (α = 0) = (3EI / ML ³ ) ^1/2 ≈31.174 sec ⁻¹ .

When the gravitational acceleration is G, when the acceleration α becomes α = 0.3G = 0.3 × 9800 mm / sec ² , ω _n (α = 0.3G) = {3 (EI / ML ³ −α / 2L)} ^1/2 ≈ 30.607 sec ^-1 . Therefore, r (α = 0.3G) = ω / ω _n ≈31.174 / 30.607≈1.0185.

At this time, the phase delay φ becomes φ (α = 0.3G) ≈110.134 ° (ζ = 0.1) φ (α = 0.3G) ≈126.250 ° (ζ = 0.05) .. Since φ (α = 0) = 90 ° when the acceleration α = 0, the phase φ becomes 110.134 ° −90 ° = 20.134 ° (ζ = 0 when the acceleration α = 0.3G is applied. .1) Change by 126.250 ° -90 ° = 36.25 ° (ζ = 0.05).

Similarly, when the acceleration α becomes α = −0.3G = −0.3 × 9800 mm / sec ² , ω _n (α = −0.3G) = {3 (EI / ML ³ −α / 2L )} ^1/2 ≈ 31.730 Therefore, r (α = -0.3G) = ω / ω _n = 31.174 / 31.130≈0.9825.

At this time, the phase delay φ is φ (α = -0.3G) ≈69.191 ° (ζ = 0.1) φ (α = 0.3G) ≈52.761 ° (ζ = 0.05) Therefore, the phase φ is 69.191 ° -90 ° = -20.809 ° (ζ = 0.1) 52.761 ° -90 ° = -37.139 ° when acceleration α = -0.3G is applied. It changes by (ζ = 0.05).

From the above, the mass M shown in FIG.
When forced oscillation is performed at nωt, the phase delay angle φ changes greatly when the acceleration α acts in the X-axis direction. Therefore, by detecting the phase delay angle φ by the displacement detection means 18, the unknown acceleration α can be known. it can. Then, as shown in FIG.
A sawtooth wave is generated in synchronization with sinωt, and t ₁ −t ₀ or t ₃
If −t ₂ is calculated, the phase delay φ can be calculated.

In the present invention, the change in the acceleration β in the direction of gravity can also be detected. In this case, α = G + β is set, and β is used as a variable instead of α, and similarly obtained.

Next, the displacement detecting means 18 used in this embodiment will be described with reference to FIGS.
FIG. 5 is a vertical sectional view of a photoelectric encoder 18 which constitutes a displacement detecting means according to one embodiment of the present invention.
Further, FIG. 6 shows a sectional view taken along the line VI-VI of FIG.
In the figure, the photoelectric encoder 18 is a movable scale 2
2 and the fixed scale 60, and detects the relative movement amount of both scales. On the upper surface of the fixed scale 60 in FIG. 5, one light emitting element 62 and four light receiving elements 64a,
64b, ..., 64d are arranged. The lead wires of the light emitting element 62 and each light receiving element 64 are fixed to the printed circuit board 66. The movable scale 22 is provided with a first lattice 68 shown in FIG. 7, and a lattice orthogonal to the Y axis is formed.

On the other hand, the fixed scale 60 has a second grating 72 and third gratings 74a, 74a, as apparent from FIG.
b, ... 74d. The second grating 72 is a transmissive grating corresponding to the light emitting element 62, and the third gratings 74a, 74b, ...
4a, 64b, ... 64d.
Therefore, the light L emitted from the light emitting element 62 is reflected by the second grating 7
2 is reflected by the first grating 68, and the reflected light passes through the third gratings 74a, 74b ,.
The light is received at 64b, ..., 64d. As described above, the photoelectric encoder according to the present embodiment is configured so that the second grating portion 72, the first grating 68, and the third grating 74 with respect to the relative movement in the Y-axis direction.
74d, light receiving elements 64a, 64b, ... 6
4d functions as a three-lattice type displacement detector.

That is, the three-lattice type displacement detector detects the amount of displacement by the change in the overlapping of three lattices as shown in FIG. 9 (Journal of the optical society).
of America, 1965, vol.55, No.4, p373-381). The three-lattice type displacement detector shown in FIG. 9 has a second lattice 7 arranged in parallel.
The second and third gratings 74, the first grating 68 arranged in parallel between the two gratings 72, 74 so as to be relatively movable, the light emitting element 62 arranged on the left side of the second grating 72 in the drawing, and the first grating 68 And a light receiving element 64 arranged on the right side of the three gratings 74 in the drawing. Then, the light emitted from the light emitting element 62 passes through the second grating 72, the first grating 68, and the third grating 74, and the light receiving element 6
4, the light receiving element 64 photoelectrically converts the illumination light limited by the gratings 72, 68, 74 and further amplifies it by the preamplifier 78 to obtain the detection signal s.

Here, when the first grating 68 moves relative to the second grating 72 and the third grating 74 in the Y direction, for example, the gratings 72, 6 of the illumination light from the light emitting element 62 are moved.
The amount of light blocked by 8, 74 gradually changes, and the detection signal s is output as a substantially sine wave. The pitch P ₁ of the first grating 68 corresponds to the wavelength P of the detection signal s, and the first grating 68 is determined from the wavelength of the detection signal s and its division value.
The relative movement amount of is measured. Therefore, by disposing the first grating 68 on the movable scale 22 and the second grating 72 and the third grating 74 on the fixed scale 60, the relative movement amount of both scales can be detected.

The third lattice 74a has an Ay phase lattice, the third lattice 74b has an Ay 'phase lattice, and the third lattice 7
A 4 phase grating is formed on 4c, and a By'phase grating is formed on the third grating 74d at a pitch P ₃ in parallel with the X axis. Therefore, if Ay = O °, then Ay '= 180 ° (1 / 2P ₃ different) By = 90 ° (1 / 4P ₃ different) By' = 270 ° (3 / 4P ₃ different) The scale is attached like this.

As a result, the light receiving elements 64a, 64b, 64
From c and 64d, A with a phase shift of π / 2 each
Signals of y-phase, Ay'-phase, By-phase, and By'-phase can be obtained, and the Ay-phase output amplified by the differential amplitude amplification from the Ay-phase-Ay'-phase and the differential amplitude from the By-phase-By'-phase. Amplified B
Obtain the y-phase output. Then, the relative movement direction of the scale in the X direction is discriminated from the phase shift direction of the Ay phase output and the By phase output, and the detection signal is electrically divided to detect the displacement amount with high resolution. ing. As described above, the displacement detecting unit 18 according to the present embodiment can accurately detect the moving direction and the moving distance in the Y direction in a non-contact manner.

As described above, according to the acceleration detecting device of this embodiment, the vibrator 14 can be made to have an extremely simple structure, and it is not necessary to attach a piezoelectric element or the like, so that the error can be reduced. You can Further, since the vibration is detected using the photoelectric encoder that is not in contact with the vibrator, the acceleration can be measured with high resolution and high accuracy. Further, in the above-described embodiment, it is preferable that the base 12 and the vibrator 14 have substantially the same linear expansion coefficient.

That is, if the linear expansion coefficients of the base 12 and the vibrator 14 are greatly different, the gap between the movable scale 22 and the fixed scale 60 may change due to temperature change, which may increase the measurement error. The voltage applied to the excitation coil can be pulsed or sinusoidal. FIG. 10 shows an acceleration detecting device according to a second embodiment of the present invention. A portion corresponding to the above-mentioned conventional technique is shown by adding reference numeral 100 and its explanation is omitted. The acceleration detection device 110 shown in the figure includes acceleration detection units 110a and 110b having the same configuration and oriented in opposite directions. In addition,
The configuration of each acceleration detection unit 110a, 110b is the same as that of the acceleration detection device 10 shown in FIG.

In this embodiment, the outputs of the acceleration detectors 110a and 110b are combined to double the detection capability and offset the error factors such as drift. Further, in the present embodiment, the acceleration can be detected not by the phase difference φ but by the frequency change of the vibrators 114a and 114b. That is, the vibrators 114a, 1
If the frequencies of 14b are f ₁ and f ₂ , respectively, the following equation 1
3 and the relational expression shown in Expression 14 are established.

## EQU13 ## 2πf ₁ = (3EI / ML ³ -3α / 2L) ^1/2

[Equation 14] 2πf ₂ = (3EI / ML ³ + 3α / 2L) ^{1/2 From the} above Equation 13,

(2πf ₁ ) ² = 3EI / ML ³ −3α / 2L From the above formula 14,

## EQU16 ## (2πf ₂ ) ² = 3EI / ML ³ + 3α / 2L.

[Mathematical formula-see original document] When Equations (15)-(16) are obtained, 4π ² (f ₂ ² −f ₁ ² ) = 3α / L α = 4π ² L (f ₂ ² −f ₁ ² ) / 3 = 4π ² L (f ₂₋ f ₁ ) (f ₂ + f ₁ ) / 3 Since π and L are constants, the acceleration α can be calculated by measuring f ₂ and f ₁ . Therefore, in this case, the displacement detecting means 118a and 118b are
The frequency is calculated from each displacement.

Further, in each of the above embodiments, the velocity V can be obtained by detecting the acceleration α and integrating it over time, and the displacement can be obtained by further integrating the velocity V over time. Therefore, the present invention can be used not only for acceleration but also for detection of velocity and displacement of a moving object. As described above, when the acceleration detecting device according to the present invention is used for detecting the velocity and the displacement amount,
Accurate detection can be performed for a long time. That is, the conventional speed detection of a private car or the like is performed by detecting the rotation of the wheels and multiplying the outer peripheral length of the tire, but this has the drawback that the accuracy deteriorates when the tire wears. It was However, when the acceleration detecting device according to the present invention is used, since the acceleration is detected in a non-contact manner, accurate speed and displacement amount calculation can be continued for a long period of time.

[0032]

As described above, according to the acceleration detecting apparatus of the present invention, the vibration force is applied to the vibrating means in the direction orthogonal to the extending direction, and the displacement of the vibrating means in the vibrating direction is detected. Since the acceleration is calculated in this manner, the acceleration can be accurately detected with a simple configuration.

[Brief description of drawings]

[Figure 1]

FIG. 2 is an explanatory diagram of an acceleration detection principle of the present invention.

FIG. 3 is a configuration diagram of an acceleration detection device according to a first embodiment of the present invention.

FIG. 4 is an explanatory diagram of a detection state of the acceleration detection device according to the first embodiment of the present invention.

[Figure 5]

FIG. 6,

[Fig. 7]

[FIG. 8]

FIG. 9 is an explanatory diagram of displacement detecting means used in the acceleration detecting device according to the first embodiment of the present invention.

FIG. 10 is an explanatory diagram of an acceleration detecting device according to a second embodiment of the present invention.

[Explanation of symbols]

 10,110 Acceleration detecting device 14,114 Vibrating means 16,116 Vibrating means 18,118 Displacement detecting means

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shingo Kuroki 165 Sakado, Takatsu-ku, Kawasaki-shi, Kanagawa Mitutoyo R & D Co., Ltd.

Claims (1)

Claim: What is claimed is: 1. A vibrating means extending substantially in an acceleration application direction, a vibrating means for applying a vibrating force to the vibrating means in a direction orthogonal to the extending direction, and a vibration of the vibrating means. An acceleration detecting device comprising: a displacement detecting unit that detects displacement in a direction.