Note: Descriptions are shown in the official language in which they were submitted.
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VIBRATION SENSORS FOR USE IN MICRO-GRAVITY ENVIRONMENT
This is a divisional application of Canadian Patent
Application Serial No. 2,096,069 filed on May 12, 1993, and
entitled "Vibration Detection and Reduction System for Use
in Micro-Gravity Environment".
BACKGROUND OF THE INVENTION
1. Field of the Invention:
The present invention relates to the art of
grasping factors for destroying a micro-gravity environment
of instruments used in a micro-gravity environment such as a
space station, an artificial satellite, a space vehicle, a
micro-gravity environment system or the like to establish a
counter-measure, and also relates to detection of positions
and scales of collision of a meteoroid-debris colliding
against these space stations.
Also, the present invention relates to vibration
measuring sensors for measuring vibrations of an instrument
used in a micro-gravity environment.
2. Description of the Prior Art:
Recently, various experiments and communication
services have been offered by means of space missions of
space stations, space shuttles and the like. As one of the
most important problems of this space mission, maintenance
of micro-gravity (~ - G: for instance 1 x 10-5G or less)
environment is pointed out.
However, in some cases, this micro-gravity
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environment is destroyed by vibrations or the like generated
due to various causes. Also, sensors for accurately
detecting arbitrary vibrations such as vibration energy,
a frequency, an amplitude or the like as is the'case with
the meteoroid/debris collisions, are not present~
In order to maintain this micro-gravity .
environment, it is desirable to grasp the factors of
vibrations destroying the micro-gravity environment and to
take a counter-measure for reducing the vibrations.
However, in the prior art such counter-measures were not
taken. Also, in an assembly of complicated systems such as
a space station or the like, it is difficult to grasp a
source of generation of vibrations including the collision
vibrations of meteoroid/debris.
Furthermore, it is the real status of the art that
a procedure for grasping various vibrations under a ~ - G
(micro-gravity) environment has not yet been established.
For instance, a vibration (acceleration) sensor in the prior
art measures a vibration (acceleration) by measuring a
movement of a vibrator supported by a spring and a material
having an inherent damping characteristic such as a damper.
However, such sensor involves a problem that it is limited
in a frequency or the like of detectable vibrations and it
cannot accurately detect vibrations under a micro-gravity
environment.
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Such type of problems are also the same even in
a micro-gravity environment system equipped on the ground or
in an airplane.
SUMMARY OF THE INVENTION: . ~
The present invention has been worked out under
the above-mentioned circumstance, and it is one object of
the present invention to provide a system which makes it
possible to grasp factors for destroying a micro-gravity
environment and to establish a counter-measure against
them.
Another object of the present invention is to
provide detector means which can accurately detect
vibrations under a micro-gravity environment.
In order to achieve the above-mentioned object,
the vibration factor analyzing system for use in a micro-
gravity environment according to the present invention
comprises:
vibration sensors disposed in (a linear array,
a matrix-like array or the like) on a vibrating body
(a space station or the like) held in a micro-gravity
environment;
analyzing means for collecting vibration data
detected by the aforementioned vibration sensors and
analyzing vibration spectra;
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a neural network section for specifying
a vibration source on the basis of the vibration spectra
analyzed by the above-mentioned analyzing means;
actuators disposed on the above-mentioned
vibrating body; and
a fuzzy control section responsive to v,ibration
. energy and a vibration source specified by the
aforementioned neural network section for controllably
driving the above-mentioned actuators so as to reduce
harmful vibrations and/or eliminating the factors of
vibrations.
With the vibration factor analyzing system for use
in a micro-gravity environment having the above-described
construction, the system itself can achieve optimum driving
of the actuators for reducing vibrations or analytic
elimination (stoppage) and reduction (lowering of a
rotational speed or the like) of the vibration factors
(meteoroid/debris collision vibration sources; motors,
pumps, etc.) by collecting vibration data and judging. In
addition, its performance including an analyzing capability
can be improved by itself by again taking in the result of
control and learning in the neural network section and the
fuzzy control section to be ready for next occurrence of
vibrations.
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In yet another aspect, the present invention
provides a vibration sensor for measuring vibrations under a
micro-gravity environment, comprising: a reflector disposed
as floating in a micro-gravity space and consisting of a
polyhedron having an arbitrary number of surfaces for
reflecting a predetermined energy; output means fixed to a
vibrating body for irradiating said reflector with said
predetermined energy; and receiving means fixed to said
vibrating body for receiving reflection energy reflected
from said reflector and measuring the natures of vibrations
of said vibrating body on the basis of variations of said
reflection energy.
In yet another aspect, the present invention
provides a vibration sensor for detecting vibrations under a
micro-gravity environment, comprising: a transparent
refractor disposed as floating in a micro-gravity space; an
irradiator disposed on one side of said transparent
refractor and fixed to a structure whose vibrations are to
be detected for irradiating with light rays; and a light
receiver disposed on the other side of said transparent
refractor as opposed to said irradiator and fixed to said
structure for receiving the light rays radiated by the
irradiator via the transparent refractor.
In yet another aspect, the present invention provides a
vibration factor analyzing system for use in a micro-gravity
environment, comprising: a plurality of vibration sensors
according to the present invention disposed on a vibrating
body held under a micro-gravity environment; analyzing means
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for collecting vibration data and vibration spectra; a
factor extracting section for specifying a vibration source
on the basis of the vibration spectra analyzed by said
analyzing means; actuators disposed on said vibrating body;
and an actuator control section responsive to vibration
energy detected by said vibration sensor and said vibration
source specified by said factor extracting section for
controllably driving some of said actuators so as to achieve
one or both of a reduction in harmful vibrations and
elimination of the factors of vibrations.
In a further aspect, the present invention relates
to a vibration sensor for measuring vibrations under a
micro-gravity environment, comprising: a reflector disposed
as floating in a micro-gravity space and consisting of a
polyhedron having an arbitrary number of surfaces for
reflecting a predetermined energy; output means fixed to a
vibrating body for irradiating said reflector with said
predetermined energy; and receiving means fixed to said
vibrating body for receiving reflection energy reflected
from said reflector and measuring the natures of vibrations
of said vibrating body on the basis of variations of said
reflection energy; wherein there is provided active
vibration suppressing means for holding said reflector
stationary in a micro-gravity space.
In a further aspect, the present invention
provides a vibration sensor for detecting vibrations under a
micro-gravity environment, comprising: a transparent
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B
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refractor disposed as floating in a micro-gravity space;
an irradiator disposed on one side of said transparent
refractor and fixed to a structure whose vibrations are to
be detected for irradiating with light rays; and a light
receiver disposed on the other side of said transparent
refractor as opposed to said irradiator and fixed to said
structure for receiving the light rays radiated by the
irradiator via the transparent refractor; wherein there is
provided active vibration suppressing means for holding said
refractor stationary in a micro-gravity space.
In a still further aspect, the present invention
relates to a vibration factor analyzing system for use in a
micro-gravity environment, comprising: a plurality of
vibration sensors disposed on a vibrating body held under a
micro-gravity environment; analyzing means for collecting
vibration data and vibration spectra; a neural network
extracting section for specifying a vibration source on the
basis of the vibration spectra analyzed by said analyzing
means; actuators disposed on said vibration body; and a
fuzzy control section responsive to vibration energy
detected by said vibration sensor and said vibration source
specified by said neural network section for controllably
driving some of said actuators so as to achieve one or both
of a reduction of harmful vibrations and elimination of the
factors of vibrations; and wherein vibration sensor
comprises: a reflector disposed as floating in a micro-
gravity space and consisting of a polyhedron having an
B
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arbitrary number of surfaces reflecting predetermined energy
having various frequencies; output means fixed to a
vibration body for irradiating said reflector with said
predetermined energy; and receiving means fixed to said
vibration body for receiving reflection energy reflected
from said reflector and measuring the natures of vibrations
of said vibrating body on the basis of variations of said
reflection energy.
In a further aspect, the present invention relates
to a vibration factor analyzing system for use in a micro-
gravity environment, comprising: a plurality of vibration
sensors disposed on a vibrating body held under a micro-
gravity environment; analyzing means for collecting
vibration data and vibration spectra; a neural network
extracting section for specifying a vibration source on the
basis of the vibration spectra analyzed by said analyzing
means; actuators disposed on said vibration body; and a
fuzzy control section responsive to vibration energy
detected by said vibration sensor and said vibration source
specified by said neural network section for controllably
driving some of said actuators so as to achieve one or both
of a reduction of harmful vibrations and elimination of the
factors of vibrations; and wherein vibration sensor
comprises: a transparent refractor disposed as floating in a
micro-gravity space; an irradiator disposed on one side of
said transparent refractor and fixed to a structure whose
vibrations are to be detected for irradiating with light
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rays; and a light receiver disposed on the other side of
said transparent refractor as opposed to said irradiator and
fixed to said structure for receiving the light rays
radiated by the irradiator via the transparent refractor.
Also, in order to achieve the above-mentioned
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second object, the vibration sensor for use in a micro-
gravity environment according to the present invention
comprises:
a reflector disposed as floating in-a micro-
gravity space (surrounded by vacuum or arbitrary~gas) and
consisting of a polyhedron having an arbitrary number
of surfaces (1 - ~ surfaces (= sphere)) reflecting
predetermined energy such as laser beams, light,
electromagnetic waves, sound waves and the like having
various frequencies according to known characteristics;
output means fixed to a vibrating body (a space
station structure or the like) for irradiating the above-
mentioned reflector with the aforementioned predetermined
energy; and
receiving means fixed to the above-mentioned
vibrating body for receiving reflection energy reflected
from the above-mentioned reflector and measuring the
natures (acceleration, amplitude, frequency, etc.) of
vibrations of the above-mentioned vibrating body on the
basis of variations of the aforementioned reflection
energy.
The above-described vibration sensor for use in
a micro-gravity environment according to the present
invention does not employ members for supporting a vibrator
such as a spring, a damper and the like as used in the
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conventional vibration sensor, but keeps a reflector
consisting of a polyhedron having an arbitrary number of
surfaces in an unvibrating condition floating in a zero-
gravity environment. And while the output meana for
irradiating the reflector with energy and the receiving
means vibrate jointly with the vibrator, the reflector does
not vibrate. Accordingly, minute acceleration/amplitude/
gravity and the like can be detected by measuring variations
of received energy by the receiving means. Since the
reflector is not supported, a range of measurement for the
nature (acceleration, amplitude, frequency, etc.) of the
detected vibration is not subjected to limitation.
Also, another micro-gravitational vibration sensor
according to the present invention comprises a transparent
refractor disposed as floating in a micro-gravity space and
having known characteristics, an irradiator disposed on one
side of the same transparent refractor and fixed to a
structure whose vibrations are to be detected for irradiat-
ing with light rays, and a light recei-ver disposed on the
other side of the above-mentioned transparent refractor as
opposed to the same irradiator and fixed to the above-
mentioned structure for receiving the light rays radiated
by the irradiator via the transparent refractor. Here,
the term "refractor" includes a lens and a prism.
In this micro-gravity vibration sensor, while
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the irradiator and the light receiver would vibrate jointly
with the structure when the structure vibrates because
they are fixed to the structure, the transparent refractor
would not vibrate because it is floating in a mlcro-gravity
space.
The light rays radiated from the above-mentioned
irradiator make incidence to the transparent refractor,
then permeate through the transparent refractor after having
been subjected to refraction and convergence corresponding
to a curved surface configuration, a polyhedron con-
figuration or a configuration consisting of a combination
of planes and curved surfaces of the transparent refractor,
and are received by the light receiver. However, in the
event that the above-described structure is vibrating,
since the transparent refractor is held stationary, a light
receiving position on a light receiving surface of the
above-described light receiver is displaced from the light
receiving position in the case where the above-mentioned
structure is held stationary by the amount corresponding
to the vibration of the structure and the characteristics
of the refractor.
The displacement of the light receiving position
on the light receiving surface of the above-mentioned light
receiver is input to a computer, and the computer having
this displacement input calculates an acceleration, an
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amplitude, a frequency and the like of the structure by
making use of the characteristics of the refractor which are
determined by the known configuration of the transparent
refractor, and outputs them.
With the above-described construction and
operation, a vibration sensor which can detect even a minute
vibration of a structure under a micro-gravity environment,
can be realized.
In addition according to the present invention,
the above-described vibration sensor is provided with active
vibration-suppressing means for making a reflector or a
transparent refractor held stationary in a zero-gravity
space, and thereby movements of the reflector or the
transparent refractor are suppressed within a predetermined
range.
The above-mentioned and other objects, features
and advantages of the present invention will become more
apparent by reference to the following description of a
number of preferred embodiments of the present invention
taken in conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS:
In the accompanying drawings:
- Fig. l(a) is a front view showing a space station
according to one preferred embodiment of the present
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invention;
Fig. l(b) is a cross-section view taken along line
A-A in Fig. l(a) as viewed in the direction of arrows;
Fig. 2 is a flow diagram showing flows of
functions of data processing according to a first preferred
embodiment of the present invention;
Fig. 3 is a flow diagram of a system software for
realizing the data processing shown in Fig. 2;
Fig. 4 is a diagram showing one example of initial
threshold values;
Fig. 5 is a perspective view showing a fixed state
of a reflector mirror of a vibration sensor according to a
first preferred embodiment of the present invention;
Fig. 6 is a perspective view showing a working
state of a vibration sensor according to a first preferred
embodiment of the present invention;
Fig. 7 is a schematic view of a vibration sensor
according to a second preferred embodiment of the present
invention, Fig. 7(a) being a schematic view showing the
state where a lens is fixed, and Figs. 7(b) and 7(c),
respectively, are schematic views showing a mode of
operation;
Fig. 8 is a cross-section view partly cut away and
partly in block form of a vibration sensor according to a
third preferred embodiment of the present invention, in
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which a reflector is kept fixed;
Fig. 9 is a cross-section view partly cut away and
partly in block form of the vibration sensor according to
the third preferred embodiment of the present i-nvention,
which shows a working state of the vibration sensor; and
Fig. 10 is a flow chart showing an operation
sequence of the vibration sensor according to the third
preferred embodiment of the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS:
In the following, a number of preferred
embodiments of the present invention will be described in
greater detail with reference to the drawings.
As shown in Fig. 1, onto an outer peripheral
surface of an airframe of a space station 1 and on the
inboard thereof are stuck a large number of vibration
sensors (three-dimensional acceleration sensors) 2 in
a matrix array at predetermined intervals.
The respective vibration sensors 2 serve to detect
vibrations of the airframe of the space station 1, the
detected vibration data are collected in a DIU (Data
Interface Unit) sampling unit 4 via transmission paths 3
consisting of coaxial cables, twist cables, optical fibers,
or the like, and they are fed to a computer 5 via this DIU
sampling unit 4;
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The computer 5 detects a scale and factors of
destruction of a micro-gravity (~ - G) on the basis of
the data transmitted from the respective vibration sensor.
Furthermore, in order to offset the detected vibrations,
the computer 5 selects actuators 6 provided on the airframe,
and drives the selected one. If necessary, the computer 5
performs elimination of the factors (vibration generation
sources) or reduction of the factors. The computer 5 grasps
the result of driving of the actuator 6 and the result of
elimination or reduction of the factors by continuous
vibration detection data sent from the vibration sensors 2.
The flow of a series of system analysis by means
of the computer 5 is shown in Fig. 2.
In a block (a) in Fig. 2, initial threshold values
of vibration are set for the respective vibration sensors 2
on the basis of various standards, for instance, on the
basis of the regulation of NASA (National Aeronautics and
Space Administration).
Next, as shown in a block (c), vibrations
generated by important causes of generation of harmful
vibrations such as operations by crews, driving of various
motors, joining of a space shuttle, collision of meteoroid/
debris and the like are detected by the vibration sensors 2,
and spectral distributions thereof are calculated. Then,
the produced spectral distribution and the initial threshold
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values are superposed as shown in block (b), and composite
data are obtained.
The composite data produced in the block (b) are
stored in a memory represented by a block (d). In a block
(e), a principal factor of the vibrations is extracted as by
comparing the vibration spectra with the initial threshold
values. Practically, among the composite data, spectra at
the protruding portions are detected, and the principal
factors of the vibrations having the respective spectra are
specifically determined. This block (e) is constructed of
neural networks formed in a software fashion.
In order to reduce the vibrations caused by the
principal factor which were determined in the block (e),
selection of actuators 6 that is effective for offsetting
the harmful vibrations is effected and an amount of control
for the selected actuator is calculated in a block (f).
In addition, in the event that the harmful vibrations cannot
be reduced to a predetermined level or lower only by driving
the actuator 6, commands for adjusting the movements of
crews and the operations of instruments serving as the
factors, are issued.
On the basis of the calculation in the block (f),
a block (g) outputs commands for selection of the actuators,
adjustment of a control amount and operation control of the
z5 instruments serving as the factor of the harmful vibrations,
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and a command for adjusting the movements of crews and the
operations of instruments serving as the factors. This
block (g) is constructed of fuzzy logics.
On the basis of the commands sent from the block
(g), in a block (h), a control signal is actually sent to
the actuator 6 to control the actuator 6. Also, the block
(g) selects and controls the actuator 6 so as to reduce
vibrations expected to arise according to a programmed
schedule through feed-forward control based on mission
schedule data. In addition, a necessary alarm is output.
The results of these series of control are
analyzed by making them once more pass through a software
corresponding to the block (f) and a block (g), and they are
stored as data in the block (d). In other words, after the
actuator 6 was driven, vibrations of an airframe are again
detected by the vibration sensors 2, thus the factors are
detected, and selection of an actuator 6 which is effective
for offsetting harmful vibrations as well as calculation of
a control amount are effected. Furthermore, commands for
selection of an actuator, adjustment of a control amount and
operation control of the instruments serving as the factors
of harmful vibrations, are issued, and they are reserved as
data in the block (d).
- By comparing the data stored in the block (d) with
the initial threshold values and the factors, compensative
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operations (control amount and the like) to be set in the
block (f) are reset so that further effective control may be
effected for the harmful vibrations to be generated by the
respective factors next time. In other words,;learning is
caused. With regard to meteoroid/debris vibrations, they
are classified as special vibrations and stored as data, and
also commands are sent to crews of a space station or a
space shuttle or to the ground station.
Fig. 3 shows flows and constructions of a software
for this system. In Fig. 3, a section-A shows a data input
portion, in which detection of vibration data by the
vibration sensors 2 are effected, and which inputs, checks
and arranges data representing the status of the vibration
source within the system such as a mission schedule
(traveling programs and docking of a space shuttle), a motor
or the like.
A section-B is a neural network routine, in which
spectral analysis and vibration mode analysis are carried
out, and classification of the factors as well as prepara-
tion of a threshold value curve are effected. In addition,
the section-B investigates data fed back from a section-C
as will be described later, prepares (calculates) a new
threshold value curve and causes the data to be stored in
a memory device.
A section-C is a fuzzy reasoning routine, in which
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a degree of working of an alarm or an actuator is judged on
the basis of the factor analysis in the neural network
portion of the section-B and the threshold value curve, and
the data are reserved. Furthermore, in the section-C,
operations of the source of the factors of vibrations are
adjusted on the basis of the result of judgement (for
example, a rotational speed of a motor or a pumping is
lowered.), and/or a control amount of an actuator for use in
active control is set, and further, an alarm is issued. In
addition, in the section-C, the actuator 6 or the like is
controlled so as to reduce vibrations expected to occur
according to a programmed schedule by feed-forward control
on the basis of the mission schedule data input in the
section-A.
With the above-described construction, owing to
the learning and predicting functions of the software
forming the neural network section and the fuzzy section,
even with respect to a space environment which cannot be
verified at the time of development of this system on the
ground, an accumulation of data after launching to the space
can be applied to the system as empirical values, and so, a
system performance is improved in the cosmic space. Also,
even in a micro-gravity environment system installed on the
ground or in a airplane or the like, it is possible to
specifically determine and reduce causes of generation of
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harmful vibrations which destroy the micro-gravity
environment.
Now, one example of a construction and an
operation of a vibration sensor 2 used in the above-
described embodiment will be described in detail~ ~
The vibration sensor according to the il~ustratedembodiment is composed of a reflection mirror (reflection
plates) 10 consisting of a polyhedron having an arbitrary
number of surfaces (one surface to ~ surfaces (sphere)),
a laser irradiator 8 for irradiating the reflection mirror
10 with light, a laser beam receiver 9 for receiving a laser
beam reflected by the reflection mirror lO, and further a
support mechanism 7 for supporting the reflection mirror lO.
The laser irradiator 8, the laser beam receiver 9 and the
support mechanism 7 are fixed to an airframe of the space
station 1.
Fig. 5 shows the state where the reflection mirror
10 is fixed by means of the support mechanism 7.
It is to be noted that in the case of disposing
a plurality of laser irradiators 48, lt is made possible to
dispose them so that the frequencies or wavelengths (colors)
of the emitted laser beams may be different, and thereby
erroneous reading by light receivers 49 are obviated.
- Fig. 6 shows a working state of this vibration
sensor 2 under a micro-gravity environment. A supporting
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mechanism 7 holes the reflection mirror 10 floating in a
zero-gravity space. At this time, the surroundings of the
reflector mirror lO could be either vacuum or any arbitrary
gas, and the reflector mirror 10 is held in a non-
support/non-vibration state.
However, owing to enclosure of gas and active
vibration-suppressing (loudspeaker, microphone, etc.)
functions, it is possible to detect vibrations while
carrying out three-dimensional position control of the
reflector mirror 3 by moving the reflector mirror 10 within
a predetermined range in the initial stage or in a
continuous or intermittent manner and by applying deviation
of detected waves caused by natural vibration within gas or
rotation of the reflector mirror 10 simultaneously to a
control filter.
It is to be noted that the gas and active
vibration-suppression can be selectively made operable (in
use) or inoperable.
The laser beam emitted by the laser irradiator 8
is reflected by the reflector mirror 10, and received by
the laser beam receiver 9. It is possible to improve a
detection capability for vibrations by inserting any
arbitrary number of separate reflection mirrors in the
opti-cal path extending from the irradiator 8 via the
reflection mirror 10 up to the laser beam receiver 9 and
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thereby elongating the optical path. The laser beam
receiver 9 detects an amplitude, a frequency and the like of
the vibration of the received laser beam. The laser beam
receiver 9 detect the amplitude and the frequency of the
vibration on the basis of movement of the received laser
beam. The vibration data detected in the laser beam
receiver 9 are transmitted to the computer 5, ànalyzed
therein and used for control and the like of the above-
mentioned actuators 6.
While a system in which a laser beam is emitted
from a laser irradiator 8, then reflected by a reflection
mirror 10 and received by a laser beam receiver 9 was
described in the above-mentioned preferred embodiment, the
present invention is not limited to such system, but any
arbitrary energy such as light (visible light, invisible
light) having various frequencies, electromagnetic waves,
sound waves or the like could be employed.
A second preferred embodiment of a vibration
sensor according to the present inventlon is shown in Fig.
7. The vibration sensors 22 according to this preferred
embodiment shown in Fig. 7 are arrayed in multiple at a pre-
determined interval in a matrix-like array on a structure
such as a space station 1 or the like as shown in Fig. 1,
they are connected to a computer 5 via a DIU (Data Interface
Unit) sampling unit 4 to measure vibrations of the
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structure, and the computer 5 controls the actuators 6 to
suppress vibrations of the structure.
In the preferred embodiment shown in Fig. 7, a
vibration sensor 22 comprises a laser irradiator 28, a laser
beam receiver 29 disposed in opposition to the same
irradiator 28, composed of charge-coupled devices (CCD) or
the like and fixed to a structure, a lens 30 or a prism 33
consisting of a polyhedron having an arbitrary number of
surfaces disposed between the same laser beam receiver 29
and the above-mentioned laser irradiator 28, made of
predetermined material and having predetermined curvature or
curved surface configurations, and a supporting device 27
provided so as to be detachable from and attachable to the
same lens 30 or prism 33 and fixed to the structure.
In the above-described vibration sensor, in the
case of measuring vibrations of a structure under a micro-
gravity environment, at first, starting from the state where
the supporting device 27 supports a lens or a prism 33 as
shown in Fig. 7(a), the support of the lens 30 or prism 33
by the supporting device 27 is released as shown in Fig.
7(b), and the lens 30 or prism 33 is held floating in a
space. This is possible owing to the fact that the space is
a micro-gravity space.
- If a laser beam is emitted from the laser
irradiator under the above-mentioned condition, then the
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laser beam makes incidence to the lens 30 or prism 33, in
the lens 30 or prism 33 the laser beam is subjected to
refraction and convergence corresponding to the char-
acteristics determined by the curved surface configuration
or the configuration of the polyhedron of the lens 30 or
prism 33, and penetrates therethrough, and it is received by
the laser beam receiver 29. The respective laser beam
receivers 29 having received the laser beam output the laser
beam reception data, the respective laser beam reception
data are collected in a DIU sampling unit 4 via transmission
paths 3 consisting of coaxial cables, twist cables, optical
fibers, or the like as shown in Fig. 1, and they are
transmitted to a computer 5 via this DIU sampling unit 4.
In the event that the above-described structure
vibrate, while the laser irradiator 28 and the laser beam
receiver 29 vibrate jointly with the structure, slnce the.
lens 30 or prism 33 is held floating in the space and is
kept stationary, a receiving position of the laser beam
emitted by the laser irradiator 28 on-the beam receiving
surface of the laser beam receiver 29 would vary in a mode
corresponding to the characteristics determined by the
vibration of the structure and the configuration of the lens
30 or prism 33.
~ With regard to the receiving position of a laser
beam on the receiving surface of the laser beam receiver 29,
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as shown in detail in Figs. 7(b) and 7(c), a displacement in
the Y-axis direction is represented by a variable Yl, a
displacement in the Z-axis direction is represented by a
variable Zl' and a displacement in the X-axis direction is
represented by a variable X1 which is obtained by converting
a variable of an image area ~ - ~ into a distance.
The above-described variables representing the
displacements in the directions of X-, Y- and Z-axes, are
input to the computer 5 via the DIU sampling unit 4, and
since the characteristics of the lens 30 and prism 33 are
known, the computer 5 calculates the acceleration,
amplitude, frequency and the like of the vibration of the
structure by making use of these known characteristics,
displays them, and also performs control of the actuators 6
necessitated for suppression of vibrations.
Through the above-mentioned procedure, a vibration
sensor capable of detecting a minute vibration of a
structure under a micro-gravity environment, has been
realized. ~
It is to be noted that while the above-described
preferred embodiment concerns a vibration sensor making use
of a laser beam, it can be modified to a vibration sensor
making use of light, electromagnetic waves or sound waves
having any arbitrary frequency by replacing an oscillator
and an oscillation receiver which can emit and receive
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light, electromagnetic waves or sound waves having any
arbitrary frequency, for the above-mentioned laser ir-
radiator and laser beam receiver, and substituting members
capable of refracting, converging and allowing to penetrate
the respective waves for the lens or prism. In addition, in
the case where a plurality of laser irradiator 8 are
provided, it is preferable that the frequencies or wave-
lengths (colors) of the irradiating laser beams can be set
differently so as to obviate erroneous reading by the laser
beam receivers 9.
Also, the illustrated system can perform detection
of vibrations while it is carrying out three-dimensional
position control of the lens 30 and prism 33 by moving the
lens 30 and prism 33 within a predetermined range in the
initial stage or in a continuous or intermittent manner and
applying deviations of the detected waves caused by natural
vibration or rotation within gas of the lens 30 or prism 33
simultaneously to a control filter, owing to enclosure of
gas and active vibration suppression (loudspeaker,
microphone, etc.) functions.
Here, the enclosure of gas and active vibration
suppression and the like could be such that selection of an
operable (used) state and an inoperable (unused) state is
possible.
Furthérmore, it is possible to elongate or change
~5~
an optical path and thereby improve a detection capability
for vibrations by inserting any arbitrary number of
reflection mirrors or separate lenses or prisms in the path
extending from the irradiator 8 via the lens 30 or prism 33
up to the laser beam receiver 29.
Next description will be made on a third,preferred
embodiment of the vibration sensor according to the present
invention with reference to Figs. 8 to 10.
The vibration sensor according to this preferred
embodiment is composed of a reflector 50 consisting of a
polyhedron having any number of surfaces (1 to ~ surfaces
(sphere)), a laser irradiator 48 for irradiating the
reflector 50 with laser beam, a planar laser beam receiver
49 constructed of CCD's so as to receive a laser beam
reflected by the reflector 50, and further, a support
mechanism 47 for holding the reflector 50. The laser
irradiator 48, the laser beam receiver 49 and the supporting
mechanism 47 are fixed to an airframe of a space station 1.
Fig. 8 shows the state where the reflector 50 is
fixed by means of the supporting mechanism 47.
It is to be noted that in the case of providing
a plurality of laser irradiators 48, it is made possible to
dlfferently set the fre~uencies, wavelengths or colors of
the-emitted laser beams so that erroneous reading by the
laser beam receiver 49 may be obviated.
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Fig. 9 shows a working state of this vibration
sensor 2 under a micro-gravity environment. Although
illustration is omitted, the supporting mechanism 47 is
separated from the reflector 50 as gently attracted towards
the inner surface of the laser beam receiver 49 by means of
a support structure driver 57, and holds the reflector 50 in
the condition of floating in a zero-gravity space. At this
time, the surroundings of the reflector 50 could be either
vacuum or any arbitrary gas, and the reflector 50 is held in
a non-support/non-vibration state.
However, in the case of carrying out the following
treatment, the illustrated system is possible to detect
vibrations while performing three-dimensional position
control of the reflector 50 by moving the reflector 50
within a predetermined range in the initial stage or in a
continuous or intermittent fashion with the aid of enclosure
of gas and active vibration-suppressing (loudspeaker,
microphone, etc.) functions and simultaneously applying
a deviation of detected waves caused by natural vibration
in gas or rotation of the reflector 50 to a control filter.
It is to be noted that with regard to gas, active
vibration-suppressing and the like, it is possible to select
elther to operate (use) or not to operate.
~ Laser beams emitted from the laser irradiators 48
are reflected by the reflector 50, and received by the laser
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beam receivers 49. It is to be noted that it is possible
to improve a vibration detecting capability by inserting any
arbitrary number of separate reflector mirrors in the path
extending from the irradiator 48 via the reflector SO up to
the laser beam receiver 49 and thereby elongating the
optical path. The laser beam receiver 49 detects qn
amplitude, a frequency and the like of the vibration of the
received laser beam. The laser beam receiver 49 detects an
amplitude and a frequency of a vibration on the basis of
movement of the received laser beam. The vibration data
detected by the laser beam detector 49 are sent to a
computer 5, then analyzed, and used for control or the like
of the above-described actuators 6.
A sensor body frame 51 is fixed to a space station
structure 1 and supports the laser irradiators 48 and the
like.
A laser irradiator power supply controller 52
controls electric power fed to the respective laser
irradiators 48, frequencies of the emitted laser beams and
the like.
A laser beam reception data sampling unit 53
processes the data of vibration loci of laser beams emitted
from the respective laser irradiators 48, then reflected by
the~reflector 50 and received on the laser beam receiving
surface of the laser beam receiver 49, and transmits the
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processed data to the CPU 54.
The CPU 54 consists of function coupling means as
shown in Fig. 10, and it performs the following operations.
At first, a detection start command is received
from a command bus 58. The detection start command is
transmitted to a support command generator 72 after it has
been confirmed by scheduling means 71 that the command
fulfils a necessary condition and a time condition, and then
a support release command is issued to a support structure
drive controller 56. In response to this command, the
support structure drive controller 56 calculates a support
release speed, a timing and the like and instructs these to
a support structure driving device 57, hence support of the
reflector 50 by the support mechanism 47 is released, and
the reflector 50 is caused to float in a zero-gravity space.
Next, under the floating condition of the
reflector 50, laser beam irradiation for the purpose of
calibration is instructed from the scheduling means 71 to a
laser beam emission controller 73. In response to this
instruction, after a detailed process such as selection of
the laser irradiators 48 has been clarified, the laser beam
emission controller 73 instructs to a laser irradiator power
supply controller 52, and the same laser irradiator power
supply controller 52 allots laser wavelengths, electric
power supplies and the like to the respective laser
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~ 1 ~54 73
irradiators 48 as described previously.
At the time of calibration, laser beams are
emitted from all the laser irradiators 48 towards the
reflector 50. Laser beams reflected by the reflectors 50
are received by the laser beam receivers 49, and..the
reception signals are transferred as data to the lqser beam
reception data sampling unit 53. Here, the laser beam
reception data sampling unit 53 performs simple calculations
by means of a large amount of data to seek for vibrating
direction characteristics and coordinate transformations for
the respective wavelengths, that is, for the respective
colors, and outputs them to a reflector motion calculator 74
of the CPU 53.
In the reflector motion calculator 74, the
position and motion such as speed, acceleration, amplitude,
period and the like of the reflector 50 are calculated by.
making use of these data. Then it outputs the calculated
reflector motion to a controller 63 for active vibration
suppression of the reflector to cause a wave projector 62 to
be controlled by the reflector active vibration-suppressing
controller 63 so that a wave opposite to the reflector
motion may be formed in a thin gas so as to hold the
reflector 50 within a predetermined space. It is to be
noted that while a low-frequency loudspeaker is most
commonly used as the wave projector 62, besides other means
~ 1 ~54 73
for applying a wave to gas such as a high-frequency sound
wave generator can be employed.
Under the condition that the reflector 50 could be
stopped in motion or could be suppressed to a vibrating
state in a predetermined range, the motion of the reflector
under this stationary state is input to a memory 55, and it
is later used as a filter.
The above-described is a procedure of calibration,
and now description will be made on the operation of the CPU
54 in the case of measuring vibrations as a vibration
sensor.
In the case of vibration measurement also, the
laser irradiator 48 is held in an ON state continuously
from the time of calibration, hence while the laser beam
reflected from the reflector 50 is being received by the
laser beam receiver 49, the data passed through the laser.
beam reception data sampling unit 53 are processed in the
reflector motion calculator 74 to seek for motion of the
reflector 50, furthermore as described previously, the
motion under the stationary state read out of the memory
55 is input to the reflector motion calculator 74, and by
subtracting the motion from the motion at the present,
vibration of the vibration sensor is calculated.
The-calculated vibration is sent to a data transmission
bus 59.
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.~.
While a system wherein a laser beam is emitted
from the laser irradiator 48 then reflected by the reflector
50 and received by the laser beam receiver 49 has been
explained in the above-described third preferred embodiment,
the present invention is not limited to such system, but any
arbitrary energy such as light (visible light and ~nvisible
light), electromagnetic waves, sound waves or the like
having various frequencies could be employed.
In addition, while a system making use of a
reflector 50 has been disclosed in the above-described third
preferred embodiment, even if the system employs a
transparent refractor as is the case with the second
preferred embodiment, similar effects and advantages can be
obtained.
As described in detail above, according to the
present invention, maintenance of a micro-gravity
environment, which is one of the most important problems in
a pace system, a space shuttle, an artificial satelite and
in micro-gravity environmental system on an aircraft and on
the ground, becomes possible.
Also, owing to learning and predicting functions
by a software of the system, even with respect to a space
environment which cannot be verified at the time of develop-
ment of this system on the ground, accumulation of data
after launching to the space can be utilized for the system
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as empirical values. Accordingly, a performance of a system
is in itself improved in the cosmic space.
In addition, with the vibration sensor according
to the present invention, vibrations can be measured
accurately under a micro-gravity environment. Moreover,
since the reflector mirror has no support, a measurable
range of the nature (acceleration, amplitude, frequency,
etc.) of the vibrations to be detected is not subjected to
any limitation.
While a principle of the present invention has
been described above in connection to preferred embodiments
of the invention, it is intended that all matter contained
in the above specification and illustrated in the accompany-
ing drawings shall be interpreted to be illustrative and not
in a limiting sense.
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