Omni range inclino-compass

A solid-state omni range incline-compass having a gravity sensor and a geomagnetic flux sensor provided on, each of three orthogonal axes established on a moving body a unit for generating a mathematic horizontal plane by making a gimbal mechanism as a mathematic equation on the basis of outputs from the gravity sensor located on each of the three orthogonal axes and a unit for calculating an azimuth angle of the moving body on the basis of two orthogonal axes on the mathematic horizontal plane.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention generally relates to apparatus for measuring an 
azimuth and an inclination angle and, more particularly, is directed to an 
omni range incline-compass. 
2. Description of the Related Art 
In the art, a compass and an inclinometer have been produced as independent 
units and each mechanism of the compass and the inclinometer has a movable 
portion. Because the compass and the inclinometer are produced as the 
respectively independent units as described above, they cannot be used 
conveniently. Also, the conventional compass and inclinometer have the 
movable portions as described above and therefore they are poor in 
durability. 
OBJECTS AND SUMMARY OF THE INVENTION 
Accordingly, it is an object of the present invention to provide an 
improved omni range incline-compass in which the aforementioned 
shortcomings and disadvantages encountered with the prior art can be 
eliminated. 
More specifically, it is an object of the present invention to provide an 
omni range inclino-compass of solid-state type which has no movable 
portion. 
Another object of the present invention is to provide an omni range 
inclino-compass of solid-state type in which azimuth angle, front and 
rear, right and left inclined angles can be measured and indicated in a 
complex fashion. 
According to an aspect of the present invention, a solid-state omni range 
inclino-compass is comprised of a gravity sensor and a geomagnetic flux 
sensor provided on each of three orthogonal axes established on a moving 
body, a device for generating a mathematic horizontal compass by making a 
gimbal mechanism as a mathematic equation on the basis of outputs from the 
gravity sensor located on each of the three orthogonal axes, a device for 
calculating a geomagnetic azimuth angle of the moving body on the basis of 
two orthogonal axes on the mathematic horizontal compass. 
The above and other objects, features, and advantages of the present 
invention will become apparent from the following detailed description of 
an illustrative embodiment thereof to be read in conjunction with the 
accompanying drawings, in which like reference numerals are used to 
identify the same or similar parts in the several views.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
The present invention will now be described in detail with reference to the 
accompanying drawings. 
FIG. 1 is a schematic diagram showing a partly cross-sectional fashion an 
example of a gravity detecting sensor used in a measuring unit according 
to the embodiment of the present invention. In FIG. 1, reference symbol 
OSC represents a high frequency generating source, C.sub.1 and C.sub.2 
capacitors, D.sub.1 and D.sub.2 diodes, L.sub.1 and L.sub.2 coils, each 
having a dust core, S a circular diaphragm, m a weight made of, for 
example, brass, 1 a casing, and 2 and 3 output terminals. As shown in FIG. 
1, the weight m is attached to the center of the diaphragm S and the 
diaphragm S is secured at the circumferential edge thereof to the circular 
inner wall of the casing 1. The coils L.sub.1 and L.sub.2 form a pair of 
inductance arms neighboring a bridge circuit having the high frequency 
generating source OSC. The two rectifiers (diodes) D.sub.1 and D.sub.2 are 
unilateral rectifiers as seen from the side of the high frequency 
generating source OSC and are connected to bridge arms opposing these two 
inductance arms. 
With the above arrangement, if the weight m of the diaphragm S is displaced 
by a force P directed from a center line Z direction, a difference is 
produced at spacings between the coils L.sub.1, L.sub.2 and the brass 
metal surfaces of the weight m and hence a difference is produced between 
the inductances of the coils L.sub.1 and L.sub.2, whereby an output 
current is produced between the output terminals 2 and 3. That is, the 
gravity detecting sensor of this embodiment is operated as a 
displacement-type sensor. In this case, as shown in FIG. 2, when the 
center line Z of the sensor forms an angle .phi. relative to the direction 
of gravity G, Gcos.phi. is applied to the weight m as the load P so that 
the output current corresponds with the amount in which the clearance is 
changed by a load Gcos.phi.. 
FIG. 3 is a perspective view illustrating an example of a geomagnetic 
detecting sensor used in the measuring unit according to the embodiment. 
The geomagnetic detecting sensor of this embodiment is a well-known Hall 
element type sensor. In FIG. 3, reference numeral 5 denotes a 
semiconductor Hall element and reference numerals 6-1, 6-2 and 7 denote 
electrodes. If a magnetic flux B is applied to the semiconductor Hall 
element 5 in the direction at a right angle to the major surface thereof 
while a constant current is flowed through the semiconductor Hall element 
5 along the pair of electrodes 6-1 and 6-2, then this geomagnetic 
detecting sensor produces a voltage V.sub.H in the axial direction at a 
right angle to both directions of the current I and the magnetic flux B. 
The electrode 7 derives this voltage V.sub.H. In this case, the following 
equation (1) is established: 
EQU V.sub.H =K.sub.H .multidot.I.multidot.B (1) 
where K.sub.H is the Hall constant. 
Accordingly, assuming that .PSI. is an angle formed by a rectangular axial 
line Z of the Hall element 5 relative to a magnetic flux F of the local 
earth field, then this geomagnetic detecting sensor produces a voltage in 
proportion to a magnetic flux (corresponding to the above-mentioned 
magnetic flux B) of Fcos.PSI.. 
While the diaphragm type gravity meter of the high frequency displacement 
detection system having the weight at the center is employed as the 
gravity detecting sensor and the Hall element type geomagnetic detecting 
sensor is employed as the geomagnetic detecting sensor as described above, 
a gravity meter and a fluxmeter of other types also can be utilized so 
long as they can provide necessary precision and output. 
FIG. 5 is a perspective view of the measuring unit according to the 
embodiment of the present invention. In this embodiment, a pair of the 
above-mentioned gravity detecting sensor and geomagnetic flux detecting 
sensor are attached on each of orthogonal three axes X, Y and Z of a 
moving object (moving object is not limited to vehicles, ships, airplanes 
and which includes human being) such that the center lines thereof become 
coincident with three axes X, Y and Z. In FIG. 5, reference symbols 
I.sub.X, I.sub.Y and I.sub.Z represent gravity detecting sensors and 
M.sub.X, M.sub.Y and M.sub.Z represent geomagnetic detecting sensors, 
respectively which derive gravity divided forces and geomagnetic flux 
divided forces corresponding to cosine values of the angles formed by the 
directions of gravity meters and the geomagnetic magnetic flux and the 
three axes X, Y, Z of the moving object, respectively. 
In this embodiment, on the basis of the outputs of the gravity sensors and 
magnetic flux sensors disposed on each of the three axes X, Y, Z, a 
mathematic gimbal type compass whose model is the mechanical type gimbal 
compass calculates the azimuthal angle and the inclination angle by the 
moving body on which the embodiment is mounted. Initially, an inclined 
angle .beta. of the deck in the pitching direction and an inclined angle 
.alpha. of the gimbal in the rolling direction are calculated by the 
gravity detecting sensors located on the three axes. As shown in FIG. 6, 
it is assumed that the orthogonal coordinate systems O-X'Y'Z' are obtained 
by rotating the orthogonal three axes coordinate systems O-XYZ about Y 
axis by .beta.. Subsequently, it is assumed that the orthogonal three axes 
coordinate systems O-.xi..eta..zeta. are obtained by rotating the 
orthogonal three axes coordinate systems O-X'Y'Z'about X' axis by .alpha.. 
At that time, the .xi.O.eta. plane of the orthogonal coordinate systems 
O-.xi..eta..zeta., forms a horizontal plane H indicated by surrounding 
line and the O.zeta. line becomes a vertical line. The above coordinate 
conversion equations are expressed as follows. 
##EQU1## 
A relation of the equation (5) shows a relation of direction cosine among 
axes of the orthogonal coordinate systems O-XYZ and O-.xi..zeta..eta.. A 
direction cosine table is represented int eh following table 1. 
TABLE 1 
______________________________________ 
O.xi. O.eta. O.zeta. 
______________________________________ 
OX COS.beta. 
sin.alpha. sin.beta. 
cos.alpha. sin.beta. 
OY 0 cos.alpha. 
sin.alpha. 
OZ 
sin.beta. sin.alpha. cos.beta. 
cos.alpha. cos.beta. 
______________________________________ 
Further, as shown in FIG. 6, an azimuth line F.sub.H having an azimuth 
angle .theta. is represented on the horizon .xi.O.eta. and a gravity line 
OW and a vertical magnetic flux Fv are represented on the vertical line 
O.zeta.. 
Incidentally, the conversion from the coordinate system O-XYZ of the moving 
object to the horizontal plane-vertical line coordinate systems 
O-.xi..eta..zeta. can be regarded as the mathematic model of the gimbal 
support geomagnetic compass having a mechanical type pendulum weight M 
shown in FIG. 7. 
As shown in FIG. 7, an outer gimbal 10 supported by a Y--Y axis (shaft) on 
the deck of the coordinate system O-XYZ of the moving object is controlled 
in a pendulum fashion by an angle .beta. by the weight M so as to urge the 
orthogonal .xi.--.xi. axis to seek the horizontal direction. An inner ring 
20 supported by the .xi.--.xi. axis (shaft) is similarly controlled in a 
pendulum fashion by an angle .alpha. by the weight M so that the 
coordinate systems O-.xi..eta..zeta. of the inner ring 20 are controlled 
by the angle .alpha. control in addition to the angle .beta. control, 
thereby being kept in the horizontal attitude. A compass card 30 having a 
compass needle within the inner ring 20 is rotated about the axis O.zeta. 
by an angle .theta. to thereby perform the north-seeking operation. 
Relations among the gravity sensors and the magnetic flux sensors on the X, 
Y, Z axes and .xi., .eta., .zeta. axes are expressed by the following 
conversion equations of mathematic gimbal where I.sub.1, I.sub.2 and 
I.sub.3 represent outputs of the gravity sensors respective axes of the 
XYZ axes. 
EQU I.sub.1 =Wcos.alpha. sin.beta. (6) 
EQU I.sub.2 =-Wsin.alpha. (7) 
EQU I.sub.3 =Wcos.alpha.cos.beta. (8) 
Assuming that N.sub.1, N.sub.2 and N.sub.3 represent output values of the 
magnetic flux sensors on the X, Y and Z axes yield the following equations 
(9), (10) and (11). 
EQU N.sub.1 =F.sub.H cos.theta.cos.beta.+(F.sub.H sin.theta.sin.alpha.+F.sub.U 
cos.alpha.) sin.beta. (9) 
EQU N.sub.2 =F.sub.H sin.theta.cos.alpha.-F.sub.U sin.alpha. (10) 
EQU N.sub.3 =-F.sub.H cos.theta.sin.beta.+(F.sub.H 
sin.theta.sin.alpha..+-.F.sub.U cos.alpha.) cos.beta. (11) 
As described above, according to this embodiment, since the function of the 
mathematic gimbal is constructed in the outputs of the gravity sensors and 
the magnetic flux sensors on the three axes X, Y, Z of the moving object, 
the azimuth angle, the pitching angle and the rolling angle can be 
obtained by the mathematic operation among data. The calculation 
processing will be described below. 
(1) Calculation A: 
The angles .alpha., .alpha. and .beta., .beta. are obtained initially. In 
this case, .alpha. and .beta. assume deck inclination angles, and .alpha. 
and .beta. assume gimbal inclination angles. Then, the following equation 
(12) is established. 
EQU .beta.=.beta., tan.alpha.=tan.alpha. cos.beta. (12) 
Then, from the equations (6) and (8), we have 
EQU .beta.=tan -1 (I.sub.1 /I.sub.3) (13) 
EQU .alpha.=tan -1 (I.sub.2 /I.sub.3) (14) 
EQU .alpha.=tan -1 (tan.alpha. cos.beta.) (15) 
Then, the output values N.sub.1, N.sub.2, N.sub.3 of the magnetic flux 
sensors are operated by using the angles .alpha. and .beta.. 
(2) Calculation B: 
Initially, values of cos.beta. and sin.beta. are put into the output of 
N.sub.1 of the content equation (equation (9)) and the output of N.sub.3 
of the content equation (equation (11) and value of .beta. is eliminated 
by calculation equation (equation (16)) and calculation equation (equation 
(17)), thereby F.sub.H cos.theta. and N.sub.4 being calculated. 
EQU N.sub.1 cos.beta.-N.sub.3 sin.beta.=F.sub.H cos.theta. (16) 
EQU N.sub.1 sin.beta.-N.sub.3 cos.beta.=F.sub.H sin.theta. sin.alpha.+F.sub.V 
cos.alpha.=N4 (17) 
The value .beta. is eliminated by the calculation equation (equation (16)) 
and the calculation equation (equation (17)) in a mathematic fashion, 
which is equivalent to the fact that the X'Y'Z' axes are established by 
rotating the Y axis by the angle .beta. in the vector diagram of FIG. 6. 
Further, this elimination of the value .beta. corresponds to the .beta. 
control of the outer gimbal 10 in the mechanism gimbal of FIG. 7. 
(3) Calculation C: 
Values of cos.alpha. and sin.alpha. are put into the output value of 
N.sub.4 (equation (17)) of the content equation obtained by the 
calculation B and the sensor output value of N.sub.2 (equation (10)) of 
the content equation and .alpha. is eliminated by the calculation of 
equation (18) to thereby obtain F.sub.H sin.theta.. 
EQU N.sub.4 sin.alpha.=N.sub.2 cos.alpha.=F.sub.H sin.theta. (18) 
Then, the elimination of .alpha. by the calculation of the equation (18) 
means the fact that the axes .xi..eta..zeta. are established by rotating 
the X' axis of the axes X'Y'Z' by .alpha. as seen from the vector diagram 
of FIG. 6 or the fact that a horizontal plane is established by 
controlling the internal gimbal by .alpha. as seen from the mechanical 
diagram of FIG. 7. 
(4) Calculation D: 
Since the coordinate systems O-.xi..eta..zeta. are obtained by the 
calculation C, the azimuth angle .theta. is obtained by using F.sub.H 
cos.theta. of the equation (16) and F.sub.H sin.theta. of the equation 
(18) according to the following equation (19) within the horizontal plane 
.xi.O.eta.. 
##EQU2## 
The mathematic processing in the equation (19) represents the synthesis of 
the azimuth lines F.sub.H in the vector diagram of FIG. 6 and also 
represents the north seeking operation of the compass needle in the 
mechanism diagram of FIG. 7. 
.theta., .alpha. and .beta. are indicated by the aforementioned calculated 
results. In this case, although the inclined angle .beta.O of the deck in 
the front to rear direction is always the same as the inclined angle 
.beta. of the gimbal in the front and rear direction, the deck left and 
right inclined angle .alpha. is not the same as the gimbal left and right 
inclined angle .alpha.. 
Accordingly, when the left and right inclined angle is displayed, it is 
possible to select one of the inclined angles .alpha. and .alpha. in 
accordance with the object to be indicated. Generally, the inclined angle 
.alpha. is preferred for indicating the substance and the inclined angle 
.alpha. is preferred for the digital indication. In any case, it is 
preferable that the inclination angle having excellent intuition is 
selected in accordance with the purpose of indication. The above-mentioned 
calculation flowchart is represented in FIG. 8. 
As described above, according to the present invention, the outputs of the 
gravity sensors and the outputs of the magnetic flux sensors respectively 
provided on three axes are calculated by the mathematic gimbal, whereby 
the azimuth, pitching and rolling inclined angles are calculated and 
indicated in a complexed fashion. A special computer program is not 
required to construct the mathematic gimbal and the mathematic gimbal is 
constructed in the outputs of the six sensors of the magnetic flux sensors 
and gravity sensors. Therefore, the calculating operation is so simple 
that it can be sufficiently executed by an 8-bit microcomputer and that 
the output can be obtained at high speed. 
Further, since the gimbal of the present invention is constructed in a 
mathematic fashion, it is possible to provide an omni range inclined angle 
and azimuth measuring apparatus which can indicate the azimuth and 
.alpha., .beta. or .alpha., .beta. can be indicated regardless of the 
attitude of the moving object, such as U-turn, lateral turning, loop, high 
speed rotation or the like. 
Furthermore, since the entirety of this omni range inclino-compass of the 
present invention including the sensors respectively provided on three 
axes is made compact and simple in arrangement, this omni range 
inclino-compass can be easily mounted on small vehicles and moving objects 
such as a human body or the like. 
According to the present invention, the horizon is obtained by the 
mathematic gimbal and the program for constructing the mathematic gimbal 
is included in the outputs of the magnetic flux sensors and gravity 
sensors. Also, since the inclination angles and azimuth angles are 
obtained by calculating the outputs, the program can be simplified and the 
calculation can be made readily. 
Since three items of the azimuth, the front and rear inclined angles and 
right and left inclined angles are indicated by the omni range 
inclino-compass of the present invention and the mathematic gimbal is 
constructed, the calculation can be executed at high speed and with high 
accuracy. 
Further, since the omni range inclino-compass of the present invention 
including the sensor and the computer includes no movable member, the omni 
range inclino-compass of the present invention can be formed as a portable 
type compass of small and simple arrangement. 
Furthermore, the omni range inclino-compass of the present invention is the 
composite measuring device which can measure azimuth, front and rear, 
right and left inclined angles unlike the conventional azimuth compass and 
inclinometer. 
Having described the preferred embodiment of the invention with reference 
to the accompanying drawings, it is to be understood that the invention is 
not limited to that precise embodiment and that various changes and 
modifications thereof could be effected by one skilled in the art without 
departing from the spirit or scope of the novel concepts of the invention 
as defined in the appended claims.