JP2003130628A - Method for detecting absolute velocity/absolute displacement and sensor for absolute velocity/absolute displacement using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method capable of lowering the natural frequency without causing the structural defect, widening the width of detectable amplitude, and excellently detecting the absolute velocity/absolute displacement even in a structure having a low natural frequency and even if the amplitude of the vibration is large, and to provide a sensor for absolute velocity/absolute displacement. SOLUTION: The sensor for absolute velocity/absolute displacement is composed of a sensor housing 2, a mass body 5 with a mass m which is supported by the sensor housing 2 using a spring with the spring constant k and a damper with the damping coefficient c, a detecting means 6 which electrically detects a relative displacement u-x of the sensor housing 2 in relation to the mass body 5, and a feedback control means 7 which positively feeds back the detected relative displacement u-x, negatively feeds back the relative acceleration obtained by secondly differentiating the detected relative displacement u-x respectively and controls the displacement of the mass body 5 caused by the absolute displacement u of the sensor housing.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vibrating body for vibrations caused by metal working machines and compressors used in factories, business establishments, and construction worksites, as well as ground, road surface vibrations, etc. caused by earthquakes, automobiles, etc. The present invention relates to a method for detecting absolute velocity / absolute displacement of a (detection object) and an absolute velocity / absolute displacement sensor using the method.

[0002]

[Problems to be Solved by the Invention] Recently, factories, business establishments,
Vibration problems occur in structures such as offices, business buildings, condominiums, and general housing due to vibrations caused by metalworking machines and compressors used in construction workshops, as well as ground and road surface vibrations caused by earthquakes and automobiles. ing. An active dynamic vibration absorber using active control may be used as a vibration isolation measure for such a general house. However, in ideal active control, an object to be controlled, that is, a vibrating body (object It is necessary to detect at least one of the absolute displacement and the absolute velocity of the structure as a detection body, and for that detection, a size sensor type displacement sensor (hereinafter referred to as a displacement sensor) directly attached to the controlled object. ) Is suitable.

However, as a result of the increase in the number of 2-story to 3-story general houses and the like due to the effective use of land and the improvement of construction technology, the natural frequency of such structures has been decreasing. Since the detectable range of the displacement sensor is equal to or higher than its own natural frequency, it is difficult to detect the absolute displacement / velocity of a structure having a natural frequency equal to or lower than the natural frequency of the displacement sensor itself. In order to reduce the natural frequency of the displacement sensor, the mass of the mass body in the displacement sensor may be increased and the mass body may be supported with low rigidity. However, such means causes the displacement sensor to become large and structurally May be vulnerable to. Further, a displacement sensor having a small detectable amplitude is not very convenient because its use is limited.

The present invention has been made in view of the above points, and an object thereof is to feed back a state quantity (displacement, velocity, acceleration) of a mass body to thereby eliminate structural defects. The natural frequency can be lowered without causing it, and the detectable amplitude can be widened. Therefore, not only when the structure has a high natural frequency and the structure vibrates at a small amplitude, the natural frequency It is an object of the present invention to provide a method capable of excellently detecting the absolute velocity / absolute displacement of a structure having a low vibration, even when vibrating with a large amplitude, and an absolute velocity / absolute displacement sensor using the method.

[0005]

The absolute velocity / absolute displacement detection method according to the first aspect of the present invention provides a method for detecting an object to be detected with respect to a mass body supported by the object with a given spring coefficient and reduction coefficient. The step of detecting the relative displacement, the detected relative displacement is positively fed, and the relative acceleration obtained by second-order differentiating the detected relative displacement is fed back negatively, respectively, and the mass caused by the absolute displacement of the detected object is detected. The method comprises the steps of controlling the displacement of the body and the step of obtaining at least one of the absolute velocity and the absolute displacement of the detected object from the detected relative displacement.

The absolute velocity / absolute displacement detection method according to the second aspect of the present invention detects the relative displacement of the object to be detected with respect to the mass body supported by the object with a given spring coefficient and reduction coefficient. From the step and the detected relative displacement, the step of controlling the displacement of the mass body caused by the absolute displacement of the object to be detected by negatively feeding back the relative acceleration obtained by differentiating the detected relative displacement from the second order. And at least one of an absolute velocity and an absolute displacement of the object to be detected.

Further, in the absolute velocity / absolute displacement detection method according to the first or second aspect of the present invention, as in the third aspect,
The method may further include a step of negatively or positively feeding back the relative velocity obtained by first-order differentiating the detected relative displacement to displace the mass body.

The method of the present invention according to any one of the above aspects may include a step of performing phase compensation when negatively feeding back the relative acceleration.

The absolute velocity / absolute displacement sensor according to the first aspect of the present invention indicates the mass supported by the object to be detected with a given spring coefficient and reduction coefficient, and the relative displacement of the object to the mass. Detecting means to detect, positive relative to this detected relative displacement, negatively fed back relative acceleration obtained by second-order differentiating the detected relative displacement, respectively, of the mass caused by the absolute displacement of the detected object Feedback control means for controlling the displacement is provided, and the feedback control means is configured to output at least one of the absolute velocity and the absolute displacement of the object to be detected from the relative displacement detected by the detection means.

The absolute velocity / absolute displacement sensor according to the second aspect of the present invention is a mass body supported by a body to be detected with a given spring coefficient and reduction coefficient, and a relative displacement of the body to be detected with respect to the mass body. And a feedback control means for controlling the displacement of the mass body caused by the absolute displacement of the detected object by negatively feeding back the relative acceleration obtained by second-order differentiating the detected relative displacement, and It is configured to output at least one of the absolute velocity and the absolute displacement of the detected object from the relative displacement detected by the detection means.

Further, in the absolute velocity / absolute displacement sensor of the first or second aspect of the present invention, as in the third aspect thereof, the feedback means is further obtained by first-order differentiating the detected relative displacement. The mass velocity may be displaced by feeding back the relative velocity negatively or positively.

In the absolute velocity / absolute displacement sensor of the present invention according to any one of the above aspects, another aspect of the present invention is provided with phase compensating means for performing phase compensation when negatively feeding back relative acceleration. May be.

In the absolute velocity / absolute displacement sensor of any one of the above aspects, the feedback control means includes an actuator for displacing the mass body with respect to the detected body by feedback.

An electromagnetic actuator can be mentioned as a preferable example of the actuator for applying the driving force to the mass body, but other actuators may be used.

According to the present invention, it is difficult to detect absolute velocity and absolute displacement unless the frequency is higher than the natural frequency of the displacement sensor itself. If the natural frequency of the displacement sensor can be lowered, the detection range can be widened. Although it is possible to detect even at low frequencies, even if the mass of the mass body is increased and the spring coefficient of the spring supporting the mass body is reduced to lower the natural frequency, the displacement sensor becomes larger and the structure is increased. In view of the possibility of becoming fragile, the natural frequency is lowered by feeding back the state quantity of the mass body by using a servo technique. That is, the detected relative displacement of the mass body is differentiated and converted into a relative velocity, and this relative velocity is further differentiated into a relative acceleration, and
These are amplified and added / subtracted as needed, and are positively or negatively fed back to displace the mass body.

In the method and sensor of the first aspect of the present invention, the detected relative displacement is fed back positively, and the relative acceleration obtained by second-order differentiating the detected relative displacement is fed back negatively, respectively, to detect the detected object. In order to control the displacement of the mass due to the absolute displacement of the body,
As will be described later, the natural frequency can be lowered, so that not only a structure with a high natural frequency but also a structure with a low natural frequency can detect its absolute velocity and absolute displacement well. it can.

In the method and sensor according to the second aspect of the present invention, the relative acceleration obtained by second-order differentiating the detected relative displacement is negatively fed back, and the mass caused by the absolute displacement of the object to be detected is fed back. In order to control the displacement of the body, the detectable amplitude can be widened as will be described later. Therefore, not only when vibrating with a small amplitude but also when vibrating with a large amplitude, the absolute velocity / absolute The displacement can be detected well.

The present invention and its embodiments will be described below based on the preferred examples shown in the drawings. The present invention is not limited to these examples.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION Referring to FIG.
The absolute displacement sensor 1 includes a sensor housing 2 as an object to be detected, and a spring coefficient k (N
/ S) and the mass 5 having a mass m (kg) supported with the reduction coefficient c (Ns / m) of the attenuator 4, and the relative displacement u-x (m) of the sensor housing 2 with respect to the mass 5.
(Where x is the absolute displacement of the mass body 5 caused by the absolute displacement u of the sensor housing 2) and the detected relative displacement u-x are positively detected. In this example, the relative velocity v obtained by first-order differentiating the relative displacement u-x is fed back negatively, and the relative acceleration a obtained by second-order differentiating the detected relative displacement u-x is fed back negatively. Feedback control means 7 for controlling the displacement of the mass body 5 caused by the absolute displacement u (m) of the sensor housing 2 is provided.

The detection means 6 calculates the relative displacement u-x as a relative displacement amplification gain (relative displacement-voltage conversion coefficient) Ka (V / m).
Therefore, an electric signal of the displacement signal eD (V) (= Ka · (u−x)) is output.

The feedback control means 7 has a displacement signal e.
Differentiating circuit 1 that differentiates D and outputs a speed signal eV (V)
5, a differentiation circuit 16 that differentiates the speed signal eV and outputs an acceleration signal eA (V), and a displacement signal eD with a displacement feedback gain KD (A / V) as a current signal iD.
(A), a converter 17 for converting the speed signal eV into a current signal -iV with a speed feedback gain -KV (A / V), and an acceleration signal eA for an acceleration feedback gain -KA (A / V). V) to a current signal-iA and a converter 19 and converters 17 and 18
And an electromagnetic actuator 20 that operates with the added current of the current signals iD, −iV, and −iA from the coil signals 19 as the coil drive current ic (A).

Each of the differentiating circuits 15 and 16 has a capacitor 25 having a capacitance Cf (F) and a resistance value Rf.
And a resistor 26 having (Ω).

The electromagnetic actuator 20 as an actuator is supplied with a coil drive current ic (= iD-i).
V-iA = KD · eD−KV · eV−KA · eA), and the coil driving force fc (N) (= Kf · ic) with the force conversion coefficient (current-force conversion coefficient) Kf (N / A). The coil driving force fc is generated and applied to the mass body 5 to displace the mass body 5 with respect to the sensor housing 2.

In the above absolute velocity / absolute displacement sensor 1, the absolute displacement u is applied to the sensor housing 2 as the object to be detected.
The equation of motion when is generated is expressed by Equation 1.

[0025]

[Formula 1]

The transfer function G (s) (= (T · s) / (T
.S + 1), where s: complex operator, T = Cf.Rf)
Since T · s << 1 in the range where s is small, the sensor housing 2 based on the equation of motion of Eq.
Transfer function eD / u between the absolute displacement u and the displacement signal eD of
When it asks, it becomes like a formula 2.

[0027]

[Equation 2] eD / u = (m · Ka · s ² ) / {(m + K
a ・ Kf ・ T ²・ KA) ・ s ² + (c + Ka ・ Kf ・ T
・ KV) ・ s + (k-Ka ・ Kf ・ KD)}

From equation 2, equations 3 and 4 are obtained when the natural frequency ωn and the damping ratio ζ of the transfer function eD / u are obtained.

[0029]

[Formula 3] ωn = {(k-Ka · Kf · KD) / (m + K
a · Kf · T ² · KA)} ^1/2

[0030]

[Formula 4] ζ = (c + Ka · Kf · T · KV) / {(m +
Ka ・ Kf ・ T ²・ KA) ・ (k-Ka ・ Kf ・ K
D)} ^1/2

The relationship between the transfer function eD / u having the natural frequency ωn and the damping ratio ζ and the frequency ω (= 2πf) is as shown in FIG.

The relative displacement u detected as the absolute displacement u
When the transfer function (u−x) / u between −x and −x is obtained, equation 5 is obtained.

[0033]

[Formula 5] (u−x) / u = m · s ² / {(m + Ka · K
f ・ T ²・ KA) ・ s ² + (c + Ka ・ Kf ・ T ・ K
V) · s + (k−Ka · Kf · KD)}

The detection range of the absolute displacement u by the absolute velocity / absolute displacement sensor 1 is a region where the natural frequency ωn or more and the magnitude (gain) of the transfer function (u−x) / u is constant. . Therefore, since the term affected by the natural frequency ωn or higher in Equation 5 is the term of s ² in both the numerator and the denominator, the transfer function (u−x) /
u becomes like Formula 6.

[0035]

[Formula 6] (u−x) / u = m / (m + Ka · Kf · T ² · KA)

Therefore, the detected relative displacement u−x is as shown in equation 7.

[0037]

[Formula 7] u−x = m · u / (m + Ka · Kf · T ² · KA)

Here, the absolute speed / absolute displacement sensor 1 is requested in accordance with structural requirements in the absolute speed / absolute displacement sensor 1.
Detectable amplitude (maximum detectable amplitude) H
The relation between (= Max · (u−x)) and the detectable amplitude (maximum detectable amplitude) U (= Max · u) of the sensor housing 2 that can be detected by the absolute velocity / absolute displacement sensor 1 is expressed by Equation 8. .

[0039]

[Formula 8] H = m · U / (m + Ka · Kf · T ² · KA)

As is clear from the above analysis of the absolute velocity / absolute displacement sensor 1, the relative term (k−Ka · Kf · KD) in the numerator term is changed by changing the relative displacement feedback gain KD in the equation (3). , Where Ka, K
Since f is positive, (k−Ka · Kf · KD) is small due to the positive feedback of the relative displacement (u−x) (note that in the negative feedback of the relative displacement (u−x), The numerator term of 3 is (k + Ka · K
f ・ KD)). Further, in Equation 3, by changing the relative acceleration feedback gain KA, the denominator (m + Ka · Kf · T ² · KA) changes, and since Ka, Kf, and T are positive, the relative acceleration a By the negative feedback of (m + Ka ・ Kf ・
T ² · KA) is larger (the relative acceleration a
In the positive feedback of, the denominator term is (m-Ka
・ Kf ・ T ²・ KA)). Therefore, in the absolute velocity / absolute displacement sensor 1, since the relative displacement (u−x) is fed back positively and the relative acceleration a is fed back negatively, the natural frequency ωn can be calculated without causing structural defects. Can be lowered.

In the absolute velocity / absolute displacement sensor 1,
As is clear from Equation 8, the relative acceleration a is negatively fed back and (Ka · Kf · T ² · K
Since A) is positive, even if the detectable amplitude H is small, a large absolute displacement u of the sensor housing 2 can be detected. In other words, detection of the absolute velocity / absolute displacement sensor 1 is possible. The possible amplitude U can be widened.

Further, in the absolute velocity / absolute displacement sensor 1,
Feedback of the relative velocity v affects only the damping ratio ζ. In Equation 4, by changing the feedback gain KV of the relative velocity v, the numerator term (c + Ka · Kf
・ T ・ KV) changes. Here, since Ka, Kf, and T are positive coefficients, since the relative speed v is negatively fed back as described above, (c + Ka · K)
f · T · KV) is increased, and the damping ratio ζ is also increased. When the relative velocity v is positively fed back, the numerator term of Equation 4 becomes (c−Ka · Kf · T · K).
V), and the damping ratio ζ can be reduced by positive feedback of the relative speed v.

Therefore, the relative displacement u-x of the sensor housing 2 with respect to the mass body 5 supported by the sensor housing 2 as the object to be detected is detected with the spring coefficient k and the reduction coefficient c, and the detected relative displacement u-x. Is positive, a relative velocity v obtained by first-order differentiating the detected relative displacement u-x is negative, and a relative acceleration a obtained by second-order differentiating the detected relative displacement u-x.
Are respectively fed back negatively to control the displacement of the mass body 5 caused by the absolute displacement u of the sensor housing 2, and the absolute velocity for executing the absolute displacement detection method.
In the absolute displacement sensor 1, the relative displacement u− of the sensor housing 2 detected from each of the output terminals 31, 32, and 33.
It is possible to obtain x, relative velocity v, and relative acceleration a by outputting them as electric signals as substantial absolute displacement, absolute velocity, and absolute acceleration.

In the above example, the differentiating circuits 15 and 16
Is composed of the capacitor 25 and the resistor 26, but the present invention is not limited to this. For example, the capacitor 25 and the resistor 26
In addition to the above, an operational amplifier may be further used or a delay device and a differential amplifier may be used instead of the capacitor 25 and the resistor 26 to configure the differentiating circuits 15 and 16, and the capacitor 25 and the resistor 26 may be included. In order to compensate the phase advance in the high frequency range due to the approximation differentiation of the differentiating circuits 15 and 16, the feedback control means 7 is provided with a phase compensating means for compensating the phase when the relative acceleration a is fed back negatively, and the relative acceleration is provided. Phase compensation may be performed when a is negatively fed back. Further, it goes without saying that other actuators may be used instead of the electromagnetic actuator 20.

Further, in the absolute speed / absolute displacement sensor 1, the sensor housing 2 is exemplified as the object to be detected, but the sensor housing 2 is, for example, a floor of a structure such as an office, a business building, an apartment house or a general house, When installed on a foundation or the like, the absolute velocity / absolute displacement sensor 1 will eventually detect the absolute velocity / absolute displacement of the floor, foundation, etc. of such a structure. Alternatively, the detected object may be a floor or foundation of a structure, and the mass 5 may be supported on the floor or foundation with a given spring coefficient and reduction coefficient to form an absolute velocity / absolute displacement sensor. . In the above example, the absolute displacement, the absolute velocity, and the absolute acceleration are obtained from each of the output terminals 31, 32, and 33 by an electric signal, but instead of this, directly on the mass body 5 or by a mechanical lever. Even if a pen or the like is attached to obtain an absolute displacement, an absolute velocity, or an absolute acceleration as a mechanical signal, further, an optical signal such as a laser beam is preferably used to obtain the absolute displacement, the absolute velocity, or the absolute velocity. You may make it obtain an absolute acceleration.

[0046]

According to the present invention, by feeding back the state quantity (displacement / speed / acceleration) of the mass body, the natural frequency can be lowered without causing structural defects. The detectable amplitude can be widened, and thus, not only when the structure has a high natural frequency and vibrates at a small amplitude, but also when the structure has a low natural frequency or a large amplitude, It is possible to provide a method capable of satisfactorily detecting the absolute velocity / absolute displacement and an absolute velocity / absolute displacement sensor using the method.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a preferred example of an embodiment of the present invention.

FIG. 2 is an operation explanatory diagram of the example shown in FIG.

[Explanation of symbols]

1 Absolute velocity / absolute displacement sensor 2 sensor housing 3 springs 4 attenuator 5 mass 6 Detection means 7 Feedback control means

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Isao Ishiguro             1-8 Kanda Surugadai, Chiyoda-ku, Tokyo Japan Univ.             Faculty of Science and Engineering F-term (reference) 2F069 AA06 GG06

Claims (9)

[Claims] 1. A relative displacement of an object to be detected with respect to a mass body supported by the object to be detected with a given spring coefficient and a reduction coefficient, and the detected relative displacement is positively,
The relative acceleration obtained by deriving the second-order derivative of the detected relative displacement is fed back negatively to control the displacement of the mass caused by the absolute displacement of the detected object, and the absolute displacement of the detected object is controlled from the detected relative displacement. An absolute velocity / absolute displacement detection method for obtaining at least one of velocity and absolute displacement. 2. A relative value obtained by detecting a relative displacement of the detected object with respect to a mass supported by the detected object with a given spring coefficient and a reduction coefficient, and deriving a second derivative of the detected relative displacement. The negative velocity of the acceleration is fed back to control the displacement of the mass caused by the absolute displacement of the detected object, and the absolute velocity and / or absolute displacement of the detected object is obtained from the detected relative displacement.
Absolute displacement detection method. 3. The displacement of the mass body caused by the absolute displacement of the object to be detected is controlled by feeding back the relative velocity obtained by first-order differentiating the detected relative displacement to the negative or the positive. Absolute velocity / absolute displacement detection method described. 4. The absolute velocity / absolute displacement detection method according to claim 1, wherein phase compensation is performed when the relative acceleration is negatively fed back. 5. A mass body supported by an object to be detected with a given spring coefficient and a reduction coefficient, a detection means for detecting relative displacement of the object to be detected with respect to the mass object, and the detected relative displacement being positive. The feedback control means for controlling the displacement of the mass body caused by the absolute displacement of the detected object by negatively feeding back the relative acceleration obtained by second-order differentiation of the detected relative displacement, An absolute velocity / absolute displacement sensor for outputting at least one of an absolute velocity and an absolute displacement of a detected object from the relative displacement detected by the detection means. 6. A mass body supported by a body to be detected with a given spring coefficient and a reduction coefficient, detection means for detecting a relative displacement of the body to be detected with respect to the mass body, and a secondary displacement of the detected relative displacement. It is provided with feedback control means for negatively feeding back the relative acceleration obtained by differentiating to control the displacement of the mass body caused by the absolute displacement of the object to be detected. An absolute velocity / absolute displacement sensor that outputs at least one of an absolute velocity and an absolute displacement of a detection object. 7. The feedback control means further feeds back the relative velocity obtained by first-order differentiating the detected relative displacement to negative or positive feedback to control the displacement of the mass body caused by the absolute displacement of the detected body. The absolute velocity / absolute displacement sensor according to claim 5 or 6, wherein 8. The absolute velocity / absolute displacement sensor according to claim 5, wherein the feedback control means includes phase compensation means for performing phase compensation when negatively feeding back the relative acceleration. . 9. The absolute velocity / absolute displacement sensor according to claim 5, wherein the feedback control means includes an actuator that displaces the mass body with respect to the detected body by feedback.