U.S. patent application number 17/393631 was filed with the patent office on 2022-02-10 for method for calculating true wind direction and true wind speed by adjusting measured values of anemometer mounted on moving body based on observation errors caused by degree of slant of moving body and device using the same.
This patent application is currently assigned to National Institute of Meteorological Sciences. The applicant listed for this patent is National Institute of Meteorological Sciences. Invention is credited to Geon Tae Kim, Seon Jeong Kim.
Application Number | 20220043019 17/393631 |
Document ID | / |
Family ID | |
Filed Date | 2022-02-10 |
United States Patent
Application |
20220043019 |
Kind Code |
A1 |
Kim; Geon Tae ; et
al. |
February 10, 2022 |
METHOD FOR CALCULATING TRUE WIND DIRECTION AND TRUE WIND SPEED BY
ADJUSTING MEASURED VALUES OF ANEMOMETER MOUNTED ON MOVING BODY
BASED ON OBSERVATION ERRORS CAUSED BY DEGREE OF SLANT OF MOVING
BODY AND DEVICE USING THE SAME
Abstract
A method for calculating a true wind direction and a true wind
speed by adjusting measured values of an anemometer mounted on a
vehicle based on observation errors caused by a degree of slant of
the vehicle and a device using the same are provided. The method
includes steps of: (I) acquiring a Gt, which is information on the
degree of slant corresponding to a current time t, from an
electronic compass module, and (II) acquiring a Wmt which is
information on a measured wind measured by the anemometer at the
current time t, to acquire a Wmt', which is information on a
measured corrected wind in a space after a first error correction
on the Wmt by referring to the Gt, to thereby calculate a first
true wind direction and a first true wind speed.
Inventors: |
Kim; Geon Tae;
(Gangneung-si, KR) ; Kim; Seon Jeong;
(Gangneung-si, KR) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
National Institute of Meteorological Sciences |
Seogwipo-si |
|
KR |
|
|
Assignee: |
National Institute of
Meteorological Sciences
Seogwipo-si
KR
|
Appl. No.: |
17/393631 |
Filed: |
August 4, 2021 |
International
Class: |
G01P 5/02 20060101
G01P005/02; G01P 13/00 20060101 G01P013/00 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 5, 2020 |
KR |
10-2020-0098233 |
Claims
1. A method for calculating a true wind direction and a true wind
speed by adjusting measured values of an anemometer mounted on a
vehicle based on observation errors caused by a degree of slant of
the vehicle, comprising steps of: (a) a true wind direction and
true wind speed calculating device on which an electronic compass
module is mounted, wherein the electronic compass module is
dependent on a degree of horizontality of the anemometer, and
wherein the degree of horizontality is changed according to the
degree of slant of the vehicle, performing a process of (I)
acquiring a Gt, which is information on the degree of slant
corresponding to a current time t, from the electronic compass
module, wherein the Gt includes: (i) information on an angle
.theta.Xt which is an angle of a Zt-axis being rotated from a
Z-axis toward an X-axis and (ii) information on an angle .theta.Yt
which is an angle of the Zt-axis being rotated from the Z-axis
toward a Y-axis, wherein the Z-axis is an axis along which gravity
acts on the vehicle, wherein the X-axis and the Y-axis included in
an XY plane are respectively related to a first direction and a
second direction, the XY plane containing current coordinates of a
predetermined reference point of the vehicle, and wherein the
Zt-axis corresponds to a vertical axis of the anemometer, and (II)
acquiring a Wmt which is information on a measured wind measured by
the anemometer at the current time t, wherein the Wmt includes
measured values of the Zt-axis, an Xt-axis and a Yt-axis, wherein
the Xt-axis in a third direction and the Yt-axis in a fourth
direction forms an XtYt plane, and wherein the XtYt plane is
perpendicular to the Zt-axis and includes the current coordinates
of the vehicle; and (b) the true wind direction and true wind speed
calculating device performing a process of acquiring a Wmt', which
is information on a measured corrected wind in a space formed by
the X-axis, the Y-axis, and the Z-axis after a first error
correction on the Wmt by referring to the Gt, to thereby calculate
a first true wind direction and a first true wind speed.
2. The method of claim 1, wherein the true wind direction and true
wind speed calculating device includes a vehicle location module
capable of acquiring information on the current coordinates of the
vehicle, and based thereon, acquiring information on a speed of the
vehicle, an acceleration of the vehicle, and a direction of the
vehicle, and wherein, after the step of (b), the method further
comprises steps of: (c) the true wind direction and true wind speed
calculating device performing a process of determining whether the
vehicle is moving by referring to at least one of the electronic
compass module and the vehicle location module, wherein the
electronic compass module contains an accelerometer capable of
measuring a change in the acceleration of the vehicle; and (d) (1)
in response to a determination that the vehicle is moving, the true
wind direction and true wind speed calculating device performing a
process of (i) (i-1) acquiring a piece of first vehicle information
including (i-1-a) information on the speed of the vehicle, the
acceleration of the vehicle and a true north of the vehicle, from
the vehicle location module, and (i-1-b) information on a heading
of the vehicle, from the electronic compass module, and (i-2)
acquiring a Wct, which is information on a relative wind caused by
the vehicle moving, based on the first vehicle information, (ii)
calculating a Wct', which is information on a corrected relative
wind in the space formed by the X-axis, the Y-axis, and the Z-axis
after a second error correction on the Wct by referring to the Gt,
and (iii) acquiring a first Wot, which is information on an
original wind in the space formed by the X-axis, the Y-axis, and
the Z-axis by referring to the first vehicle information, the Wmt',
and the Wct', to thereby calculate a (2-1)-st true wind direction
and a (2-1)-st true wind speed, (2) in response to a determination
that the vehicle is not moving, the true wind direction and true
wind speed calculating device performing a process of (i) acquiring
a piece of second vehicle information, including information on the
true north of the vehicle and the heading of the vehicle, from the
electronic compass module, and (ii) acquiring a second Wot, which
is information on an original wind in the space formed by the
X-axis, the Y-axis, and the Z-axis by referring to the second
vehicle information and the Wmt', to thereby calculate a (2-2)-nd
true wind direction and a (2-2)-nd true wind speed, and (3)
acquiring the true wind direction and the true wind speed on which
a determination as to whether the vehicle is moving is additionally
reflected by referring to the (2-1)-st true wind direction and the
(2-1)-st true wind speed and the (2-2)-nd true wind direction and
the (2-2)-nd true wind speed.
3. The method of claim 2, wherein the true wind direction and true
wind speed calculating device calculates the (2-1)-st true wind
direction and the (2-1)-st true wind speed or the (2-2)-nd true
wind direction and the (2-2)-nd true wind speed at every
predetermined measurement interval, and performing an integrated
operation on the (2-1)-st true wind direction and the (2-1)-st true
wind speed or the (2-2)-nd true wind direction and the (2-2)-nd
true wind speed, to thereby acquire a final true wind direction and
a final true wind speed as corresponding to an accumulated
measurement time.
4. The method of claim 3, wherein, at the step of (d), in response
to the determination that the vehicle is moving, (d1) the true wind
direction and true wind speed calculating device performs a process
of acquiring information on each change in the degree of slant for
each of the X-axis, the Y-axis, and the Z-axis from the electronic
compass module for a time period from a past time t_k to the
current time t which corresponds to the accumulated measurement
time, and (d2) in response to a detection on (i) a specific change
in the degree of slant that is equal to or larger than a first
threshold at a past time t_m, which is a time after the past time
t_k, and then (ii) the specific change in the degree of slant is
restored at a past time t_n, the true wind direction and true wind
speed calculating device performs a process of classifying the
first Wot, which are a Wot_m to a Wot_n measured during the past
time t_m to the past time t_n at said every predetermined
measurement interval as erroneous values, to thereby acquire the
final true wind direction and the final true wind speed after
eliminating the erroneous values or after replacing the erroneous
values with normal measured values measured right before or after
thereof.
5. The method of claim 3, wherein, at the step of (d), in response
to the determination that the vehicle is moving, (dl) the true wind
direction and true wind speed calculating device performs a process
of acquiring information on each change in the degree of slant for
each of the X-axis, the Y-axis, and the Z-axis from the electronic
compass module for a time period from a past time t_k to the
current time t which corresponds to the accumulated measurement
time, and (d2) in response to a detection on (i) a specific change
in the degree of slant that is equal to or larger than a first
threshold at the past time t_k, and then (ii) the specific change
in the degree of slant is preserved until the current time t, the
true wind direction and true wind speed calculating device performs
a process of classifying a Wot_(k-p), . . . , a Wot (k-1), Wot_k, a
Wot_(k+l), . . . , a Wot(k+q) measured during an offsetting range
from a past time t_(k-p) to a past time t_(k+q) as erroneous
values, to thereby acquire the final true wind direction and the
final true wind speed after eliminating the erroneous values or
replacing the erroneous values with normal measured values measured
right before or after thereof.
6. The method of claim 3, wherein, in response to a detection on a
cardinal number of specific erroneous values whose corresponding
changes in the degree of slant being equal to or larger than a
second threshold to be more than a predetermined percentage of a
cardinal number of specific measured values measured at said every
predetermined measurement interval during a specific accumulated
measurement time, the true wind direction and true wind speed
calculating device performs a process of classifying the specific
measured values as the erroneous values, to thereby acquire the
final true wind direction and the final true wind speed after
eliminating the erroneous values or replacing the erroneous values
with normal measured values measured right before or after
thereof.
7. A true wind direction and true wind speed calculating device for
calculating a true wind direction and a true wind speed by
adjusting measured values of an anemometer mounted on a vehicle
based on observation errors caused by a degree of slant of the
vehicle, wherein the true wind direction and true wind speed
calculating device includes an electronic compass module mounted
thereon, wherein the electronic compass module is dependent on a
degree of horizontality of the anemometer, and wherein the degree
of horizontality is changed according to the degree of slant of the
vehicle, comprising: at least one memory that stores instructions;
and at least one processor configured to execute the instructions
to perform: (I) a process of (i) acquiring a Gt, which is
information on the degree of slant corresponding to a current time
t, from the electronic compass module, wherein the Gt includes:
(i-1) information on an angle .theta.Xt which is an angle of a
Zt-axis being rotated from a Z-axis toward an X-axis and (i-2)
information on an angle .theta.Yt which is an angle of the Zt-axis
being rotated from the Z-axis toward a Y-axis, wherein the Z-axis
is an axis along which gravity acts on the vehicle, wherein the
X-axis and the Y-axis included in an XY plane are respectively
related to a first direction and a second direction, the XY plane
containing current coordinates of a predetermined reference point
of the vehicle, and wherein the Zt-axis corresponds to a vertical
axis of the anemometer, and (ii) acquiring a Wmt which is
information on a measured wind measured by the anemometer at the
current time t, wherein the Wmt includes measured values of the
Zt-axis, an Xt-axis and a Yt-axis, wherein the Xt-axis in a third
direction and the Yt-axis in a fourth direction forms an XtYt
plane, and wherein the XtYt plane is perpendicular to the Zt-axis
and includes the current coordinates of the vehicle; and (II) a
process of acquiring a Wmt', which is information on a measured
corrected wind in a space formed by the X-axis, the Y-axis, and the
Z-axis after a first error correction on the Wmt by referring to
the Gt, to thereby calculate a first true wind direction and a
first true wind speed.
8. The device of claim 7, wherein, the true wind direction and true
wind speed calculating device includes a vehicle location module
capable of acquiring information on the current coordinates of the
vehicle, and based thereon, acquiring information on a speed of the
vehicle, an acceleration of the vehicle, and a direction of the
vehicle, wherein, after the process of (II), the processor further
performs (III) a process of determining whether the vehicle is
moving by referring to at least one of the electronic compass
module and the vehicle location module, wherein the electronic
compass module contains an accelerometer capable of measuring a
change in the acceleration of the vehicle; and (IV) (1) in response
to a determination that the vehicle is moving, a process of (i)
(i-1) acquiring a piece of first vehicle information including
(i-1-a) information on the speed of the vehicle, the acceleration
of the vehicle and a true north of the vehicle, from the vehicle
location module, and (i-1-b) information on a heading of the
vehicle, from the electronic compass module, and (i-2) acquiring a
Wct, which is information on a relative wind caused by the vehicle
moving, based on the first vehicle information, (ii) calculating a
Wct', which is information on a corrected relative wind in the
space formed by the X-axis, the Y-axis, and the Z-axis after a
second error correction on the Wct by referring to the Gt, and
(iii) acquiring a first Wot, which is information on an original
wind in the space formed by the X-axis, the Y-axis, and the Z-axis
by referring to the first vehicle information, the Wmt', and the
Wct', to thereby calculate a (2-1)-st true wind direction and a
(2-1)-st true wind speed, (2) in response to a determination that
the vehicle is not moving, a process of (i) acquiring a piece of
second vehicle information, including information on the true north
of the vehicle and the heading of the vehicle, from the electronic
compass module, and (ii) acquiring a second Wot, which is
information on an original wind in the space formed by the X-axis,
the Y-axis, and the Z-axis by referring to the second vehicle
information and the Wmt', to thereby calculate a (2-2)-nd true wind
direction and a (2-2)-nd true wind speed, and (3) a process of
acquiring the true wind direction and the true wind speed on which
a determination as to whether the vehicle is moving is additionally
reflected by referring to the (2-1)-st true wind direction and the
(2-1)-st true wind speed and the (2-2)-nd true wind direction and
the (2-2)-nd true wind speed.
9. The device of claim 8, wherein, the processor performs a process
of calculating the (2-1)-st true wind direction and the (2-1)-st
true wind speed or the (2-2)-nd true wind direction and the
(2-2)-nd true wind speed, and applying an integrated operation to
the (2-1)-st true wind direction and the (2-1)-st true wind speed
or the (2-2)-nd true wind direction and the (2-2)-nd true wind
speed, to thereby acquire a final true wind direction and a final
true wind speed as corresponding to an accumulated measurement
time.
10. The device of claim 9, wherein at the process of (IV), in
response to the determination that the vehicle is moving, the
processor performs: (IV-1) a process of acquiring information on
each change in the degree of slant for each of the X-axis, the
Y-axis, and the Z-axis from the electronic compass module for a
time period from a past time t_k to the current time t which
corresponds to the accumulated measurement time, and (IV-2) in
response to a detection on (i) a specific change in the degree of
slant that is equal to or larger than a first threshold at a past
time t_m, which is a time after the past time t_k, and then (ii)
the specific change in the degree of slant is restored at a past
time t_n, a process of classifying the first Wot, which are Wot_m
to a Wot_n measured during the past time t_m to the past time t_n
at said every predetermined measurement interval as erroneous
values, to thereby acquire the final true wind direction and the
final true wind speed after eliminating the erroneous values or
after replacing the erroneous values with normal measured values
measured right before or after thereof.
11. The device of claim 9, wherein at the process of (IV), in
response to the determination that the vehicle is moving, the
processor performs: (IV-1) a process of acquiring information on
each change in the degree of slant for each of the X-axis, the
Y-axis, and the Z-axis from the electronic compass module for a
time period from a past time t_k to the current time t which
corresponds to the accumulated measurement time, and (IV-2) in
response to a detection on (i) a specific change in the degree of
slant that is equal to or larger than a first threshold at the past
time t_k, and then (ii) the specific change in the degree of slant
is preserved until the current time t, a process of classifying a
Wot_(k-p), . . . , a Wot (k-1), Wot_k, a Wot_(k+), . . . , a
Wot(k+q) measured during an offsetting range from a past time
t_(k-p) to a past time t_(k+q) as erroneous values, to thereby
acquire the final true wind direction and the final true wind speed
after eliminating the erroneous values or replacing the erroneous
values with a normal measured values measured right before or after
thereof.
12. The device of claim 9, wherein, in response to a detection on a
cardinal number of specific erroneous values whose corresponding
changes in the degree of slant being equal to or larger than a
second threshold to be more than a predetermined percentage of a
cardinal number of specific measured values measured at said every
predetermined measurement interval during a specific accumulated
measurement time, further performs a process of classifying the
specific measured values as the erroneous values, to thereby
acquire the final true wind direction and the final true wind speed
after eliminating the erroneous values or replacing the erroneous
values with a normal measured values measured right before or after
thereof.
Description
CROSS REFERENCE TO RELATING APPLICATIONS
[0001] This application claims the benefit of Korean Patent
Application No. 10-2020-0098233, filed Aug. 5, 2020, which is
incorporated herein by reference in its entirety.
FIELD OF THE DISCLOSURE
[0002] The present disclosure relates to a method for calculating a
true wind direction and a true wind speed by adjusting measured
values of an anemometer mounted on a moving body, i.e., a vehicle,
based on observation errors caused by a degree of slant of the
vehicle
BACKGROUND OF THE DISCLOSURE
[0003] Recently, along with the continuous developments of
industrial technologies, functions and performances of
meteorological instruments have also been improved, and
accordingly, more accurate meteorological data can be obtained and
a vast amount of meteorological data can be stored and analyzed.
Nevertheless, since there is a physical limitation as to a range of
measurement the meteorological instruments can measure, a void of
data due to the physical limitation is inevitable, and it is
unrealistic to install the meteorological instruments on every
sites where there are voids of data.
[0004] Therefore, a method for installing the meteorological
instruments on a vehicle was introduced. For example, the
meteorological instruments mounted on the vehicle can measure
meteorological data at a measuring site and then measure another
meteorological data at a next measuring site.
[0005] A mobile meteorological vehicle on which various
meteorological instruments such as an anemometer, etc. are
installed is known in the art. (See, e.g., "A Mobile Meteorological
Observation Vehicle?", Skylove of Korea Meteorological
Administration (February 2017)). However, an error correcting
method is necessary because meteorological instruments in a mobile
state have more errors in their collected data than other
meteorological instruments in a static state. See id.
[0006] Therefore, there is a need to propose a method for improving
an accuracy of measured values of the anemometer mounted on the
vehicle while being operated.
SUMMARY OF THE DISCLOSURE
[0007] It is an object of the present disclosure to solve all of
the aforementioned problems.
[0008] It is another object of the present disclosure to provide a
method for correcting observation errors due to a degree of slant
of a vehicle by adjusting reference axes to thereby adjust measured
values measured by a true wind direction and true wind speed
calculating device.
[0009] It is still another object of the present disclosure to
determine the degree of slant of the vehicle and accordingly
perform additional error adjusting processes.
[0010] It is still yet another object of the present disclosure to
measure a change in the degree of slant for each of the reference
axes, to thereby eliminate or replace measured values whose changes
are equal to or larger than a specific threshold.
[0011] In order to achieve the above objects and achieve the
desired results that will be introduced hereinafter, the
configuration of the present disclosure is as follows:
[0012] In accordance to one aspect of the present disclosure, there
is provided a method for calculating a true wind direction and a
true wind speed by adjusting measured values of an anemometer
mounted on a vehicle based on observation errors caused by a degree
of slant of the vehicle, including steps of: (a) a true wind
direction and true wind speed calculating device on which an
electronic compass module is mounted, wherein the electronic
compass module is dependent on a degree of horizontality of the
anemometer, and wherein the degree of horizontality is changed
according to the degree of slant of the vehicle, performing a
process of (I) acquiring a Gt, which is information on the degree
of slant corresponding to a current time t, from the electronic
compass module, wherein the Gt includes: (i) information on an
angle .theta.Xt which is an angle of a Zt-axis being rotated from a
Z-axis toward an X-axis and (ii) information on an angle .theta.Yt
which is an angle of the Zt-axis being rotated from the Z-axis
toward a Y-axis, wherein the Z-axis is an axis along which gravity
acts on the vehicle, wherein the X-axis and the Y-axis included in
an XY plane are respectively related to a first direction and a
second direction, the XY plane containing current coordinates of a
predetermined reference point of the vehicle, and wherein the
Zt-axis corresponds to a vertical axis of the anemometer, and (II)
acquiring a Wmt which is information on a measured wind measured by
the anemometer at the current time t, wherein the Wmt includes
measured values of the Zt-axis, an Xt-axis and a Yt-axis, wherein
the Xt-axis in a third direction and the Yt-axis in a fourth
direction forms an XtYt plane, and wherein the XtYt plane is
perpendicular to the Zt-axis and includes the current coordinates
of the vehicle; and (b) the true wind direction and true wind speed
calculating device performing a process of acquiring a Wmt', which
is information on a measured corrected wind in a space formed by
the X-axis, the Y-axis, and the Z-axis after a first error
correction on the Wmt by referring to the Gt, to thereby calculate
a first true wind direction and a first true wind speed.
[0013] As one example, the true wind direction and true wind speed
calculating device includes a vehicle location module capable of
acquiring information on the current coordinates of the vehicle,
and based thereon, acquiring information on a speed of the vehicle,
an acceleration of the vehicle, and a direction of the vehicle, and
wherein, after the step of (b), the method further comprises steps
of: (c) the true wind direction and true wind speed calculating
device performing a process of determining whether the vehicle is
moving by referring to at least one of the electronic compass
module and the vehicle location module, wherein the electronic
compass module contains an accelerometer capable of measuring a
change in the acceleration of the vehicle; and (d) (1) in response
to a determination that the vehicle is moving, the true wind
direction and true wind speed calculating device performing a
process of (i) (i-1) acquiring a piece of first vehicle information
including (i-1-a) information on the speed of the vehicle, the
acceleration of the vehicle and a true north of the vehicle, from
the vehicle location module, and (i-1-b) information on a heading
of the vehicle, from the electronic compass module, and (i-2)
acquiring a Wct, which is information on a relative wind caused by
the vehicle moving, based on the first vehicle information, (ii)
calculating a Wct', which is information on a corrected relative
wind in the space formed by the X-axis, the Y-axis, and the Z-axis
after a second error correction on the Wct by referring to the Gt,
and (iii) acquiring a first Wot, which is information on an
original wind in the space formed by the X-axis, the Y-axis, and
the Z-axis by referring to the first vehicle information, the Wmt',
and the Wct', to thereby calculate a (2-1)-st true wind direction
and a (2-1)-st true wind speed, (2) in response to a determination
that the vehicle is not moving, the true wind direction and true
wind speed calculating device performing a process of (i) acquiring
a piece of second vehicle information, including information on the
true north of the vehicle and the heading of the vehicle, from the
electronic compass module, and (ii) acquiring a second Wot, which
is information on an original wind in the space formed by the
X-axis, the Y-axis, and the Z-axis by referring to the second
vehicle information and the Wmt', to thereby calculate a (2-2)-nd
true wind direction and a (2-2)-nd true wind speed, and (3)
acquiring the true wind direction and the true wind speed on which
a determination as to whether the vehicle is moving is additionally
reflected by referring to the (2-1)-st true wind direction and the
(2-1)-st true wind speed and the (2-2)-nd true wind direction and
the (2-2)-nd true wind speed.
[0014] As one example, the true wind direction and true wind speed
calculating device calculates the (2-1)-st true wind direction and
the (2-1)-st true wind speed or the (2-2)-nd true wind direction
and the (2-2)-nd true wind speed at every predetermined measurement
interval, and performing an integrated operation on the (2-1)-st
true wind direction and the (2-1)-st true wind speed or the
(2-2)-nd true wind direction and the (2-2)-nd true wind speed, to
thereby acquire a final true wind direction and a final true wind
speed as corresponding to an accumulated measurement time.
[0015] As one example, at the step of (d), in response to the
determination that the vehicle is moving, (d1) the true wind
direction and true wind speed calculating device performs a process
of acquiring information on each change in the degree of slant for
each of the X-axis, the Y-axis, and the Z-axis from the electronic
compass module for a time period from a past time t_k to the
current time t which corresponds to the accumulated measurement
time, and (d2) in response to a detection on (i) a specific change
in the degree of slant that is equal to or larger than a first
threshold at a past time t_m, which is a time after the past time
t_k, and then (ii) the specific change in the degree of slant is
restored at a past time t_n, the true wind direction and true wind
speed calculating device performs a process of classifying the
first Wot, which are a Wot_m to a Wot_n measured during the past
time t_m to the past time t_n at said every predetermined
measurement interval as erroneous values, to thereby acquire the
final true wind direction and the final true wind speed after
eliminating the erroneous values or after replacing the erroneous
values with normal measured values measured right before or after
thereof.
[0016] As one example, at the step of (d), in response to the
determination that the vehicle is moving, (d1) the true wind
direction and true wind speed calculating device performs a process
of acquiring information on each change in the degree of slant for
each of the X-axis, the Y-axis, and the Z-axis from the electronic
compass module for a time period from a past time t_k to the
current time t which corresponds to the accumulated measurement
time, and (d2) in response to a detection on (i) a specific change
in the degree of slant that is equal to or larger than a first
threshold at the past time t_k, and then (ii) the specific change
in the degree of slant is preserved until the current time t, the
true wind direction and true wind speed calculating device performs
a process of classifying a Wot (k-p), . . . , a Wot(k-1), Wot_k, a
Wot_(k+1), . . . , a Wot(k+q) measured during an offsetting range
from a past time t_(k-p) to a past time t_(k+q) as erroneous
values, to thereby acquire the final true wind direction and the
final true wind speed after eliminating the erroneous values or
replacing the erroneous values with normal measured values measured
right before or after thereof.
[0017] As one example, in response to a detection on a cardinal
number of specific erroneous values whose corresponding changes in
the degree of slant being equal to or larger than a second
threshold to be more than a predetermined percentage of a cardinal
number of specific measured values measured at said every
predetermined measurement interval during a specific accumulated
measurement time, the true wind direction and true wind speed
calculating device performs a process of classifying the specific
measured values as the erroneous values, to thereby acquire the
final true wind direction and the final true wind speed after
eliminating the erroneous values or replacing the erroneous values
with normal measured values measured right before or after
thereof.
[0018] In accordance with another aspect of the present disclosure,
there is provided a true wind direction and true wind speed
calculating device for calculating a true wind direction and a true
wind speed by adjusting measured values of an anemometer mounted on
a vehicle based on observation errors caused by a degree of slant
of the vehicle, wherein the true wind direction and true wind speed
calculating device includes an electronic compass module mounted
thereon, wherein the electronic compass module is dependent on a
degree of horizontality of the anemometer, and wherein the degree
of horizontality is changed according to the degree of slant of the
vehicle, including: at least one memory that stores instructions;
and at least one processor configured to execute the instructions
to perform: (I) a process of (i) acquiring a Gt, which is
information on the degree of slant corresponding to a current time
t, from the electronic compass module, wherein the Gt includes:
(i-1) information on an angle .theta.Xt which is an angle of a
Zt-axis being rotated from a Z-axis toward an X-axis and (i-2)
information on an angle .theta.Yt which is an angle of the Zt-axis
being rotated from the Z-axis toward a Y-axis, wherein the Z-axis
is an axis along which gravity acts on the vehicle, wherein the
X-axis and the Y-axis included in an XY plane are respectively
related to a first direction and a second direction, the XY plane
containing current coordinates of a predetermined reference point
of the vehicle, and wherein the Zt-axis corresponds to a vertical
axis of the anemometer, and (ii) acquiring a Wmt which is
information on a measured wind measured by the anemometer at the
current time t, wherein the Wmt includes measured values of the
Zt-axis, an Xt-axis and a Yt-axis, wherein the Xt-axis in a third
direction and the Yt-axis in a fourth direction forms an XtYt
plane, and wherein the XtYt plane is perpendicular to the Zt-axis
and includes the current coordinates of the vehicle; and (II) a
process of acquiring a Wmt', which is information on a measured
corrected wind in a space formed by the X-axis, the Y-axis, and the
Z-axis after a first error correction on the Wmt by referring to
the Gt, to thereby calculate a first true wind direction and a
first true wind speed.
[0019] As one example, the true wind direction and true wind speed
calculating device includes a vehicle location module capable of
acquiring information on the current coordinates of the vehicle,
and based thereon, acquiring information on a speed of the vehicle,
an acceleration of the vehicle, and a direction of the vehicle,
wherein, after the process of (II), the processor further performs:
(III) a process of determining whether the vehicle is moving by
referring to at least one of the electronic compass module and the
vehicle location module, wherein the electronic compass module
contains an accelerometer capable of measuring a change in the
acceleration of the vehicle; and (IV) (1) in response to a
determination that the vehicle is moving, a process of (i) (i-1)
acquiring a piece of first vehicle information including (i-1-a)
information on the speed of the vehicle, the acceleration of the
vehicle and a true north of the vehicle, from the vehicle location
module, and (i-1-b) information on a heading of the vehicle, from
the electronic compass module, and (i-2) acquiring a Wct, which is
information on a relative wind caused by the vehicle moving, based
on the first vehicle information, (ii) calculating a Wct', which is
information on a corrected relative wind in the space formed by the
X-axis, the Y-axis, and the Z-axis after a second error correction
on the Wct by referring to the Gt, and (iii) acquiring a first Wot,
which is information on an original wind in the space formed by the
X-axis, the Y-axis, and the Z-axis by referring to the first
vehicle information, the Wmt', and the Wct', to thereby calculate a
(2-1)-st true wind direction and a (2-1)-st true wind speed, (2) in
response to a determination that the vehicle is not moving, a
process of (i) acquiring a piece of second vehicle information,
including information on the true north of the vehicle and the
heading of the vehicle, from the electronic compass module, and
(ii) acquiring a second Wot, which is information on an original
wind in the space formed by the X-axis, the Y-axis, and the Z-axis
by referring to the second vehicle information and the Wmt', to
thereby calculate a (2-2)-nd true wind direction and a (2-2)-nd
true wind speed, and (3) a process of acquiring the true wind
direction and the true wind speed on which a determination as to
whether the vehicle is moving is additionally reflected by
referring to the (2-1)-st true wind direction and the (2-1)-st true
wind speed and the (2-2)-nd true wind direction and the (2-2)-nd
true wind speed.
[0020] As one example, the processor performs a process of
calculating the (2-1)-st true wind direction and the (2-1)-st true
wind speed or the (2-2)-nd true wind direction and the (2-2)-nd
true wind speed, and applying an integrated operation to the
(2-1)-st true wind direction and the (2-1)-st true wind speed or
the (2-2)-nd true wind direction and the (2-2)-nd true wind speed,
to thereby acquire a final true wind direction and a final true
wind speed as corresponding to an accumulated measurement time.
[0021] As one example, at the process of (IV), in response to the
determination that the vehicle is moving, the processor performs:
(IV-1) a process of acquiring information on each change in the
degree of slant for each of the X-axis, the Y-axis, and the Z-axis
from the electronic compass module for a time period from a past
time t_k to the current time t which corresponds to the accumulated
measurement time, and (IV-2) in response to a detection on (i) a
specific change in the degree of slant that is equal to or larger
than a first threshold at a past time t_m, which is a time after
the past time t_k, and then (ii) the specific change in the degree
of slant is restored at a past time t_n, a process of classifying
the first Wot, which are Wot_m to a Wot_n measured during the past
time t_m to the past time t_n at said every predetermined
measurement interval as erroneous values, to thereby acquire the
final true wind direction and the final true wind speed after
eliminating the erroneous values or after replacing the erroneous
values with normal measured values measured right before or after
thereof.
[0022] As one example, wherein at the process of (IV), in response
to the determination that the vehicle is moving, the processor
performs: (IV-1) a process of acquiring information on each change
in the degree of slant for each of the X-axis, the Y-axis, and the
Z-axis from the electronic compass module for a time period from a
past time t_k to the current time t which corresponds to the
accumulated measurement time, and (IV-2) in response to a detection
on (i) a specific change in the degree of slant that is equal to or
larger than a first threshold at the past time t_k, and then (ii)
the specific change in the degree of slant is preserved until the
current time t, a process of classifying a Wot_(k-p), . . . , a
Wot(k-1), Wot_k, a Wot_(k+1), . . . , a Wot(k+q) measured during an
offsetting range from a past time t_(k-p) to a past time t_(k+q) as
erroneous values, to thereby acquire the final true wind direction
and the final true wind speed after eliminating the erroneous
values or replacing the erroneous values with a normal measured
values measured right before or after thereof.
[0023] As one example, in response to a detection on a cardinal
number of specific erroneous values whose corresponding changes in
the degree of slant being equal to or larger than a second
threshold to be more than a predetermined percentage of a cardinal
number of specific measured values measured at said every
predetermined measurement interval during a specific accumulated
measurement time, further performs a process of classifying the
specific measured values as the erroneous values, to thereby
acquire the final true wind direction and the final true wind speed
after eliminating the erroneous values or replacing the erroneous
values with a normal measured values measured right before or after
thereof.
BRIEF DESCRIPTION OF THE DRAWINGS
[0024] The above and other objects and features of the present
disclosure will become apparent from the following description of
preferred embodiments given in conjunction with the accompanying
drawings. The accompanying drawings used to explain example
embodiments of the present disclosure are only part of example
embodiments of the present disclosure and other drawings can be
obtained based on the drawings by those skilled in the art of the
present disclosure without inventive work.
[0025] FIG. 1 is a drawing schematically illustrating a true wind
direction and true wind speed calculating device for calculating a
true wind direction and a true wind speed by adjusting observation
errors due to a degree of slant of a vehicle in accordance with one
example embodiment of the present disclosure.
[0026] FIG. 2 is a drawing schematically illustrating a concept of
a space for correcting reference axes according to the degree of
slant of the vehicle in accordance with one example embodiment of
the present disclosure.
[0027] FIG. 3 is a drawing schematically illustrating a change in
measured values depending on a slope of a ground level where the
vehicle is located in accordance with one example embodiment of the
present disclosure.
[0028] FIG. 4 is a drawing illustrating changes in the reference
axes due to a change in the slope of the ground level, and changes
in the space due thereto in accordance with one example embodiment
of the present disclosure.
[0029] FIG. 5 is a drawing illustrating a deviation of the measured
values from a true wind direction and a true wind speed due to a
relative wind caused by the vehicle in accordance with one example
embodiment of the present disclosure.
[0030] FIG. 6A is a drawing illustrating a change in the degree of
slant of the vehicle due to a sharp decrease in speed of the
vehicle (a sudden stop) in accordance with one example embodiment
of the present disclosure.
[0031] FIG. 6B is a drawing illustrating a change in the degree of
slant of the vehicle due to a sudden change in a path of the
vehicle in accordance with one example embodiment of the present
disclosure.
[0032] FIG. 7A is a graph illustrating, for at least one of the
reference axes, a section of a change and a restoration in the
degree of slant, to be used for determining the measured values in
the section as erroneous values in accordance with one example
embodiment of the present disclosure.
[0033] FIG. 7B is a graph illustrating, for at least one of the
reference axes, a section where the change in the degree of slant
happens and then the changed state is preserved, to be used for
determining measured values in another section as erroneous values
in accordance with one example embodiment of the present
disclosure.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0034] In the following detailed description, reference is made to
the accompanying drawings that show, by way of illustration,
specific embodiments in which the invention may be practiced. These
embodiments are described in sufficient detail to enable those
skilled in the art to practice the invention. It is to be
understood that the various embodiments of the present invention,
although different, are not necessarily mutually exclusive. For
example, a particular feature, structure, or characteristic
described herein in connection with one embodiment may be
implemented within other embodiments without departing from the
spirit and scope of the present invention. In addition, it is to be
understood that the position or arrangement of individual elements
within each disclosed embodiment may be modified without departing
from the spirit and scope of the present invention. The following
detailed description is, therefore, not to be taken in a limiting
sense, and the scope of the present invention is defined only by
the appended claims, appropriately interpreted, along with the full
range of equivalents to which the claims are entitled. In the
drawings, like numerals refer to the same or similar functionality
throughout the several views.
[0035] To allow those skilled in the art to carry out the present
invention easily, the example embodiments of the present invention
by referring to attached diagrams will be explained in detail as
shown below.
[0036] FIG. 1 is a drawing schematically illustrating a true wind
direction and true wind speed calculating device for calculating a
true wind direction and a true wind speed by adjusting observation
errors due to a degree of slant of a vehicle in accordance with one
example embodiment of the present disclosure.
[0037] For reference, the term "slant" as used herein not only
represents angles formed by the vehicle from reference axes but
also changes in a posture of the vehicle, i.e., changes in a pitch,
a roll and a yaw, according to the movement of the vehicle.
[0038] Referring to FIG. 1, the true wind direction and true wind
speed calculating device 100 for calculating the true wind
direction and the true wind speed by adjusting the observations
errors due to the degree of slant of the vehicle may include a
memory 110 and a processor 120. Herein, the memory 110 may store
instructions of the processor 120, wherein the instructions are
specifically codes generated for the purpose of allowing the true
wind direction and true wind speed calculating device to function
in a specific manner, and can be implemented in a form of
executable program command through a variety of computer means
recordable to computer readable media. The instructions may execute
processes for performing functions described herein.
[0039] Additionally, the processor 120 of the true wind direction
and true wind speed calculating device 100 may include hardware
configurations such as an MPU (Micro Processing Unit) or a CPU
(Central Processing Unit), cache memory, and data bus, etc. It may
further include an operating system, and software that perform
specific functions.
[0040] The present disclosure does not exclude a configuration of
an integrated processor, which is a structure in which both the
processor 120 and the memory 110 are integrated together as a
medium for operation.
[0041] First, the true wind direction and true wind speed
calculating device 100 may include an anemometer 11 mounted thereon
and capable of measuring a wind to acquire a wind direction and a
wind speed. Herein, the anemometer 11 may conduct measurements in
varying environments depending on a three-dimensional movement of
the vehicle, therefore, an ultrasonic anemometer capable of
measuring the three-dimensional movement may be used in lieu of a
conventional propeller-vane anemometer that is only capable of
measuring a two-dimensional movement.
[0042] Also, the true wind direction and true wind speed
calculating device 100 may include an electronic compass module 200
for acquiring information on the degree of slant of the vehicle.
Herein, the degree of slant may change depending on a slope of a
ground level the vehicle is located or depending on a change in a
posture of the vehicle. Therefore, a degree of horizontality on the
electronic compass module 200 may be changed accordingly. Herein
the degree of horizontality is changed according to the degree of
slant of the vehicle. Additionally, the electronic compass module
200 may include a geomagnetic sensor, an accelerometer, and a gyro
sensor in order to acquire information on a change in the degree of
slant of the vehicle, and information on a direction such as a true
north, and information on a heading of the vehicle.
[0043] Also, the true wind direction and true wind speed
calculating device 100 may be interworked with a vehicle location
module 300 capable of acquiring a current coordinates of the
vehicle 10, and based thereon, acquiring information on a speed of
the vehicle, an acceleration of the vehicle, the direction of the
vehicle, and the true north of the vehicle in order to eliminate
errors in the measured values of the electronic compass module 200
that may occur when the vehicle is moving. Herein, the vehicle
location module 300 can be a GPS module or type of GNSS module that
can perform similar required functions.
[0044] Since the true wind direction and true wind speed
calculating device 100 as described above, mounted on the vehicle
10, is specialized for conducting measurements in the varying
environments instead of conducting measurements in constant
environments, a process of correcting erroneous values acquired due
to the varying environments should be performed by reflecting a
difference between the measured values from the varying
environments and those from the constant environments, which will
be explained below.
[0045] FIG. 2 is a drawing schematically illustrating a concept of
a space for correcting the reference axes according to the degree
of slant of the vehicle in accordance with one example embodiment
of the present disclosure.
[0046] Referring to FIG. 2, the true wind direction and wind speed
calculating device 100 may correct the reference axes in order to
adjust the observation errors due to the degree of slant of the
vehicle.
[0047] Specifically, the true wind direction and true wind speed
calculating device 100 can perform a process of acquiring a Gt,
which is information on the degree of slant corresponding to a
current time t. Herein, the Gt includes (i) information on an angle
.theta.Xt 501 which is an angle of a Zt-axis 530 being rotated from
a Z-axis 430 toward an X-axis 410 and (ii) information on an angle
.theta.Yt 502 which is an angle of the Zt-axis 530 being rotated
from the Z-axis 430 toward a Y-axis 420. Herein, the Z-axis 430 is
an axis along which gravity acts on the vehicle, the X-axis 410 and
the Y-axis 420 included in an XY plane are respectively related to
a first direction and a second direction, the XY plane containing
current coordinates of a predetermined reference point of the
vehicle, and the Zt-axis corresponds to a vertical axis of the
anemometer 11. That is, the angle .theta.Xt 501 is an angle formed
when the vehicle rotates with the Y-axis 420 serving as a rotation
axis, and the angle .theta.Yt 502 is an angle formed when the
vehicle rotates with the X-axis 410 serving as the rotation axis,
and based thereon, an angle from the Zt-axis 530 and the Z-axis 430
can also be calculated. However, the angle from the Zt-axis 530 and
the Z-axis 430 is different from an angle .theta.Zt (not
illustrated), which is an angle formed when the vehicle rotates
with the Z-axis serving the rotation axis, therefore, it is not
illustrated. (.theta.Zt corresponds to a yaw of the vehicle
10).
[0048] Subsequently, the true wind direction and true wind speed
calculating device 100 may perform a process of acquiring a Wmt
which is information on a measured wind measured by the anemometer
11 at the current time t. Herein, the Wmt may include measured
values corresponding to Zt-axis 530, an Xt-axis (not shown) and a
Yt-axis (not shown). Herein, the Xt-axis in a third direction and
the Yt-axis in a fourth direction form an XtYt plane which includes
current coordinates of the vehicle and is perpendicular to the
Zt-axis 530.
[0049] For reference, the Xt-axis, the Yt-axis and the XtYt plane
is perpendicular to the Zt-axis 530, and for clarity, FIG. 2
illustrates the Zt-axis 530 only.
[0050] Also, if the first direction of the X-axis 410 and the
second direction of the Y-axis 420 are different from the third
direction of the Xt-axis and the fourth direction of the Y-axis
respectively but correspond to the third direction of the Xt-axis
and the fourth direction of the Y-axis respectively, there should
be additional computations to reflect differences therebetween on a
calculation of a first error correction that will be mentioned
hereinafter, however, if the first direction and the third
direction are set to be equal and the second direction and the
fourth direction are set to be equal, the additional computations
may be omitted. That is, whether the additional computations are
required depends on the operating conditions of the present
disclosure.
[0051] Subsequently, the true wind direction and true wind speed
calculating device 100 refers to the Gt to perform the first error
correction on the Wmt, to thereby acquire a Wmt' which is
information on the corrected measured wind in a space formed by the
X-axis 410, the Y-axis 420, and the Z-axis 430, and based thereon
calculates a first true wind direction and a first true wind speed
on which the degree of slant of the vehicle 10 is reflected.
[0052] That is, the true wind direction and true wind speed
calculating device may correct the measured values from the
anemometer 11 mounted on the vehicle 10 with the degree of slant
along the Zt-axis by referring to the angle .theta.Xt 501
corresponding to a rotational angle of Y-axis 420 and the angle
.theta.Yt 502 corresponding to the rotational angle of X-axis 410,
to thereby perform the first error correction and thus acquire
corrected measured values serving as values measured in the space
based on the Z-axis which is the axis along which gravity acts on
the vehicle.
[0053] FIG. 3 is a drawing schematically illustrating a change in
the measured values depending on the slope of the ground level
where the vehicle is located in accordance with one example
embodiment of the present disclosure.
[0054] Referring to FIG. 3, the first error correction as described
above can be performed as follows.
[0055] FIG. 3 illustrates the vehicle 10 with the degree of slant,
e.g., 10 degrees 550 from a horizontal plane, in a space formed by
the Xt-axis 510 which points outward from a front of the vehicle
10, the Yt-axis 520 which points outward from a left of the vehicle
10, and the Zt-axis 530, which is perpendicular to the Xt-axis 510
and the Yt-axis 520. Herein, in case the wind 600 is blowing from
the left of the vehicle 10 parallel to the horizontal plane, an
angle of the wind is 0 degree if based on the Z-axis which is
perpendicular to the horizontal plane, however, an axis of
reference should be based on the Zt-axis, which is the vertical
axis of the anemometer 11 mounted on the vehicle 10, thus, the
angle of the wind is -10 degrees. Therefore, by performing the
process of the first error correction capable of correcting the
Zt-axis 530 by the angle .theta.Yt (10 degrees), i.e., adding 10
degrees to the angle of the wind, i.e., -10 degrees, a correct
angel of 0 degree of the true wind direction based on the Z-axis
(vertical axis) can be acquired.
[0056] Further, as another example embodiment of the present
disclosure, the anemometer 11 can determine whether the vehicle 10
is moving, to thereby acquire the true wind direction and the true
wind speed.
[0057] The true wind direction and true wind speed calculating
device 100 includes a vehicle location module 300 capable of
acquiring information on the current coordinates of the vehicle,
and based thereon, acquiring information on a speed of the vehicle,
an acceleration of the vehicle, and a direction of the vehicle, and
can determine whether the vehicle 10 is moving by referring to at
least one of the electronic compass module 200 or the vehicle
location module 300. For example, the true wind direction and true
wind speed calculating device 100 can determine whether the vehicle
10 is moving by referring to changes in accelerations from the
accelerometer included in the electronic compass module 200, or
referring to the changes in locations from the vehicle location
module 300.
[0058] Afterwards, (1) in response to a determination that the
vehicle 10 is moving, the true wind direction and true wind speed
calculating device performs a process of (i) (i-1) acquiring first
vehicle information, including information on the speed of the
vehicle, the acceleration of the vehicle and a true north of the
vehicle, from the vehicle location module, and (i-2) acquiring a
Wct, which is information on a relative wind caused by the movement
of the vehicle, based on the first vehicle information, (ii)
calculating a Wct', which is information on a corrected relative
wind in the space formed by the X-axis 410, the Y-axis 420, and the
Z-axis 430 after a second error correction on the Wct by referring
to the Gt, and (iii) acquiring a first Wot, which is information on
an original wind in the space formed by the X-axis 410, the Y-axis
420, and the Z-axis 430 by referring to the first vehicle
information, the Wmt', and the Wct', to thereby calculate a
(2-1)-st true wind direction and a (2-1)-st true wind speed.
[0059] FIG. 4 is a drawing illustrating changes in the reference
axes of the vehicle due to a change in the slope of the ground
level, and changes in the space due thereto in accordance with one
example embodiment of the present disclosure.
[0060] Referring to FIG. 4, the anemometer 11 mounted on the
vehicle 10 moving in a horizontal state, as depicted on the left
side of the FIG. 4, may measure the wind direction and the wind
speed in a space defined by the Z-axis 430 and the XY plane
including a reference point of the vehicle 10. However, even when
the anemometer 11 is measuring a same wind, if the anemometer 11
mounted on the vehicle 10 is moving down a slope as depicted on the
right side of the FIG. 4, the vertical axis of the anemometer 11,
which is the Zt-axis 530, becomes out of line from the axis along
which gravity is acting on the vehicle 10, therefore differences
may occur to the measured values of the anemometer 11 under the
space defined by the Zt-axis 530 and the XtYt plane 500 and the
measured values of the anemometer 11 under the space defined by the
Z-axis 430 and the XY plane 400. Therefore, to correct such
differences, the first error correction may be performed as
mentioned hereinbefore, however, if the vehicle 10 is moving, the
anemometer 11 should take a relative wind into account.
[0061] FIG. 5 is a drawing illustrating a deviation of the measured
values from the true wind direction and the true wind speed due to
the relative wind caused by the vehicle in accordance with one
example embodiment of the present disclosure.
[0062] Referring to FIG. 5, the true wind direction and true wind
speed calculating device 100 acquires (i) first vehicle
information, including information on the speed of the vehicle, the
acceleration of the vehicle and a true north of the vehicle, from
the vehicle location module 300, and acquires a Wct, which is
information on a relative wind caused by the movement of the
vehicle, based on the first vehicle information, (ii) calculates a
Wct', which is information on a corrected relative wind in the
space formed by the X-axis 410, the Y-axis 420, and the Z-axis 430
after a second error correction on the Wct by referring to the Gt,
and (iii) acquires a first Wot 630, which is information on an
original wind in the space formed by the X-axis 410, the Y-axis
420, and the Z-axis 430 by referring to the first vehicle
information, the Wmt' 610, and the Wct' 620, to thereby calculate a
(2-1)-st true wind direction and a (2-1)-st true wind speed.
[0063] Herein, each wind information can be expressed by the
following equations.
{right arrow over (Wmt')}={right arrow over (Wot)}+{right arrow
over (Wct')} Equation 1
[0064] Additionally, in accordance with another example embodiment
of the present disclosure, if P is the measured values measured by
the anemometer 11 corresponding to {right arrow over (Wnt')}, C is
a speed of the vehicle 10 corresponding to -{right arrow over
(Wct')}, T is the original wind corresponding to {right arrow over
(Wot)}, and A is an apparent wind felt from the vehicle 10, with
small case dir standing for direction, and small case spd standing
for speed, the true wind direction T.sub.dir and the true wind
speed T.sub.spd corresponding to the {right arrow over (Wot)} can
be expressed as following equations.
A.sub.dir=P.sub.dir+C.sub.dir+180.degree. Equation 2
T.sub.u=P.sub.spd+cos(A.sub.dir)+C.sub.spd.times.cos(C.sub.dir)
T.sub.v=P.sub.spd+sin(A.sub.dir)+C.sub.spd.times.sin(C.sub.dir)
Equations 3
T.sub.spd=(T.sub.u.sup.2+T.sub.v.sup.2).sup.1/2
T.sub.dir=(arctan(T.sub.v/T.sub.u))+180.degree. Equations 4
[0065] Besides, (2) in response to a determination that the vehicle
is not moving, the true wind direction and true wind speed
calculating device 100 performs a process of (i) acquiring second
vehicle information, including information on the true north of the
vehicle and the heading of the vehicle, from the electronic compass
module 200, and (ii) acquiring a second Wot, which is information
on an original wind in the space formed by the X-axis 410, the
Y-axis 420, and the Z-axis 430 by referring to the second vehicle
information and the Wmt', to thereby calculate a (2-2)-nd true wind
direction and a (2-2)-nd true wind speed.
[0066] For example, by referring back to FIG. 3, if the vehicle 10
is stopped as depicted in FIG. 3 with the degree of slant as 10
degrees, with the heading of the vehicle 10 defined as pointing
outward from the front of the vehicle 10, and the true north
defined as pointing outward from the left of the vehicle 10 (same
as the direction of the wind 600), a direction of initial
measurement values of anemometer 11 with reference to XtYt plane
and Zt-axis is -90 degrees (west wind), and -10 degrees
respectively. Based thereon, the true wind direction and true wind
speed calculating device 100 performs the first error correction
which reflects the angle .theta.Yt which is 10 degrees, to thereby
calculate the true direction of 0 degree with reference to the
Z-axis 430.
[0067] Further, the true wind direction and true wind speed
calculating device 100 reflects the heading of the vehicle 10 which
is oriented 90 degrees eastward from the true north of the XY
plane, and as a result of performing the second error correction,
the true wind direction has a direction of 90+(-90)=0 degree in the
XY plane.
[0068] Next, in accordance with another example embodiment of the
present disclosure, the true wind direction and true wind speed
calculating device 100 calculates the (2-1)-st true wind direction
and the (2-1)-st true wind speed or the (2-2)-nd true wind
direction and the (2-2)-nd true wind speed at every predetermined
measurement interval (e.g. 1 second) and performs an integrated
operation on the (2-1)-st true wind direction and the (2-1)-st true
wind speed or the (2-2)-nd true wind direction and the (2-2)-nd
true wind speed, to thereby acquire a final true wind direction and
a final true wind speed as corresponding to an accumulated
measurement time of (e.g. 10 minutes).
[0069] Herein, the integrated operation is an operation that
calculates one single value by integrating 600 pieces of measured
wind information measured at said every one-second interval, which
is a measurement interval unit, during the accumulated measurement
time of 10 minutes, and it can simply be an operation to calculate
an average, however, depending on an implementation of the present
invention, the integrated operation may be applied differently,
such as assigning weights by referring to a variance of the
measured values.
[0070] Furthermore, as another example, if a change in the degree
of slant occurs with respect to at least one of the X-axis 410, the
Y-axis 420, and the Z-axis 430 on the premise that the integrated
operation described above is performed, there may be additional
processes such as classifying at least a portion of the measured
values as the erroneous values or replacing thereof after analyzing
the measured values.
[0071] In general, since road surfaces on which the vehicle 10
travels on have gradual changes, the possibility of a sudden change
in the slope is low. However, because the vehicle 10 is designed
for moving, there may be changes in the posture thereof, e.g., at
least the roll, the pitch and the yaw. Accordingly, additional
errors occur due to noises generated in the measured values.
[0072] FIG. 6A is a drawing illustrating a change in the degree of
slant (a change 710 in the pitch) of the vehicle due to a sharp
decrease in speed of the vehicle (a sudden stop) in accordance with
one example embodiment of the present disclosure.
[0073] FIG. 6B is a drawing illustrating a change in the degree of
slant (a change 720 in the roll) of the vehicle due to a sudden
change in a path of the vehicle in accordance with one example
embodiment of the present disclosure.
[0074] Further, though not illustrated, if the vehicle 10 is making
a left/right turn or a U-turn, the change in the yaw of the vehicle
10 may cause a change in the pitch and/or the roll together.
[0075] As described above, the change in the degree of slant due to
the posture thereof, albeit temporary and fleeting, can affect the
anemometer 11 negatively.
[0076] FIG. 7A is a graph illustrating, for at least one of the
reference axes, a section of a change and a restoration in the
degree of slant for a duration shorter than an accumulated
measurement time, to be used for determining the measured values in
the section as the erroneous values in accordance with one example
embodiment of the present disclosure.
[0077] Referring to FIG. 7A, the degree of slant of the vehicle 10
can be observed with reference to the X-axis 430, the change in the
degree of slant happened at a past time t_m before the current time
t and continued for a certain period of time 810 until a past time
t_n where the degree of slant was restored. Herein, if the
accumulated measurement time is assumed to be a duration 800 (e.g.
10 minutes) from a past time t_k to the current time t, since the
certain period of time 810 when the change in the degree of slant
happened was less than the accumulated measurement time, it may be
determined that the change in the degree of slant was due to the
movement of the vehicle 10 itself. Thus, the measured values of the
original wind of a Wot_m to a Wot_n during the past time t_m to the
past time t_n are classified as the erroneous values to be
eliminated or replaced with normal measured values (for example,
replaced with the Wot_k which is the normal measured values of the
original wind measured at the past time t_k which is before the
past time t_m) and then the integrated operation is performed.
[0078] However, unlike FIG. 7A, FIG. 7B illustrates the change in
the degree of slant being preserved for the accumulated measurement
time after a change in the degree of slant that is equal to or
larger than a first threshold happens.
[0079] FIG. 7B is a graph illustrating, for at least one of the
reference axes, a section where the change in the degree of slant
happens and then the changed state is preserved, to be used for
determining measured values in another section as erroneous values
in accordance with one example embodiment of the present
disclosure.
[0080] Referring to FIG. 7B, the degree of slant of the vehicle 10
can be observed with reference to the X-axis 430 similarly to the
FIG. 7A, and shows the change in the degree of slant occurred at
the past time t_k, which is a time before the current time t, and
preserved until the current time t. Herein, if a period of time 800
(e.g. 10 minutes) from the past time t_k to the current time t is
assumed to be the accumulated measurement time, since the change in
the degree of slant happens throughout the accumulated measurement
time, it can be determined that the change in the degree of slant
is caused by the slope of the road surface the vehicle 10 in
travelling on and not because of the movement of the vehicle 10
(such that a sudden change in the degree of slant due to the slope
of the road surface occurs at the past time t_k). Considering that
the sudden change in the degree of slant that is equal to or larger
than the first threshold may have a negative effect on a result of
the integrated operation, an offsetting range may be set and its
corresponding measured values may be classified as the erroneous
values. That is, a Wot_(k-p), . . . , a Wot(k-1), Wot_k, a
Wot_(k+1), . . . , a Wot(k+q) measured during the offsetting range
820, from a past time t_(k-p) to a past time t_(k+q) are classified
as erroneous values, to eliminate the erroneous values or replace
the erroneous values with normal measured values measured right
before or after thereof, (for example, the Wot_(k-p) of the past
time t_(k-p) is replaced with normal measured values measured
before the past time t_k to perform the integrated operation and
improve an accuracy of the result).
[0081] Afterwards, in accordance with another example embodiment of
the present disclosure, if a cardinal number of specific erroneous
values whose corresponding changes in the degree of slant being
equal to or larger than a second threshold is more than a
predetermined percentage of a cardinal number of specific measured
values measured at said every predetermined measurement interval
during a specific accumulated measurement time, the true wind
direction and true wind speed calculating device 100 performs a
process of classifying the specific measured values as the
erroneous values, and eliminate the erroneous values or replace the
erroneous values with normal measured values measured right before
or after thereof.
[0082] For example, if a change in the original wind measured for
said every predetermined measurement interval for the accumulated
measurement time of 10 minutes continues to occur with a large
discrepancy (exceeding the second threshold), and if such a large
discrepancy exceeds the predetermined percentage of the 600
measurements (e.g. 480, which is 80%), since the measured values in
the corresponding accumulated measurement time may have a negative
effect on an overall measurement result, all the measured values in
the corresponding accumulated measurement time are classified as
the erroneous values, to thereby acquire the final true wind
direction and the final true wind speed after eliminating the
erroneous values or replacing the erroneous values with normal
measured values measured right before or after thereof.
[0083] The present disclosure has an effect of providing a method
for correcting the observation errors due to the degree of slant of
the vehicle by adjusting the reference axes to thereby adjust the
measured values measured by the true wind direction and true wind
speed calculating device 100.
[0084] The present disclosure has another effect of determining
whether the vehicle is moving and accordingly performing additional
error adjusting processes.
[0085] The present disclosure has still another effect of measuring
the change in the degree of slant for each of the references axes,
to thereby eliminate or replace measured values whose changes are
equal to or larger than a specific threshold.
[0086] Besides, the embodiments of the present disclosure as
explained above can be implemented in a form of executable program
command through a variety of computer means recordable to computer
readable media. The computer readable media may store solely or in
combination, program commands, data files, and data structures. The
program commands recorded in the media may be components specially
designed for the present disclosure or may be usable for a skilled
human in a field of computer software. The computer readable media
include, but are not limited to, magnetic media such as hard
drives, floppy diskettes, magnetic tapes, memory cards, solid-state
drives, USB flash drives, optical media such as CD-ROM and DVD,
magneto-optical media such as floptical diskettes and hardware
devices such as a read-only memory (ROM), a random access memory
(RAM), and a flash memory specially designed to store and carry out
program commands. Program commands may include not only a machine
language code made by a compiler but also a high level code that
can be used by an interpreter etc., which is executed by a
computer. The aforementioned hardware device may work as more than
a software module to perform the action of the present disclosure
and they may do the same in the opposite case. The hardware device
may include a processor such as a CPU or a GPU, combined with a
memory device such as ROM or RAM to store the program commands,
configured to execute the commands stored in the memory, and a
communication part which can exchange signals with external
devices. In addition, the hardware device may include a keyboard, a
mouse, and any other external input device to receive commands
prepared by developers.
[0087] As seen above, the present disclosure has been explained by
specific matters such as detailed components, limited embodiments,
and drawings. While the invention has been shown and described with
respect to the preferred embodiments, it, however, will be
understood by those skilled in the art that various changes and
modification may be made without departing from the spirit and
scope of the invention as defined in the following claims.
[0088] Accordingly, the thought of the present disclosure must not
be confined to the explained embodiments, and the following patent
claims as well as everything including variations equal or
equivalent to the patent claims pertain to the category of the
thought of the present disclosure.
* * * * *