U.S. patent application number 14/424775 was filed with the patent office on 2015-08-20 for positioning system and method for positioning an article.
The applicant listed for this patent is AKTIEBOLAGET SKF. Invention is credited to Markus Behn.
Application Number | 20150233607 14/424775 |
Document ID | / |
Family ID | 49080900 |
Filed Date | 2015-08-20 |
United States Patent
Application |
20150233607 |
Kind Code |
A1 |
Behn; Markus |
August 20, 2015 |
POSITIONING SYSTEM AND METHOD FOR POSITIONING AN ARTICLE
Abstract
A positioning system for an object, such as a solar panel, to be
moved in a controlled manner from an initial position in a
direction of movement along a movement path including an azimuthal
component into a final position includes a preloading device
connected to the object and configured to exert a permanently
acting force on the object in the direction of movement, the force
having a component acting in an azimuthal direction, and a brake
apparatus configured to fix the object in a predetermined position
along the movement path.
Inventors: |
Behn; Markus; (Diekholzen,
DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
AKTIEBOLAGET SKF |
Goteborg |
|
SE |
|
|
Family ID: |
49080900 |
Appl. No.: |
14/424775 |
Filed: |
August 30, 2013 |
PCT Filed: |
August 30, 2013 |
PCT NO: |
PCT/EP2013/067973 |
371 Date: |
February 27, 2015 |
Current U.S.
Class: |
126/714 ;
126/600 |
Current CPC
Class: |
F24S 30/425 20180501;
Y02E 10/47 20130101; F24S 2030/19 20180501; F24S 30/40 20180501;
F24S 50/20 20180501; F24S 2030/18 20180501 |
International
Class: |
F24J 2/54 20060101
F24J002/54; F24J 2/38 20060101 F24J002/38 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 30, 2012 |
DE |
10 2012 215 358.6 |
Claims
1. A positioning system for an object to be moved in a controlled
manner from an initial position in a direction of movement along a
movement path including an azimuthal component into a final
position, comprising: a preloading device connected to the object
and configured to exert a permanently acting force on the object in
the direction of movement, wherein the force has a component acting
in an azimuthal direction; and a brake apparatus configured to fix
the object in a predetermined position along the movement path.
2. The positioning system according to claim 1, wherein the
preloading device comprises an element that can store potential
energy such that the force is generated by the stored potential
energy.
3. The positioning system according to claim 2, wherein the
preloading device comprises a spring tensionable against the
movement path and/or a weight, movable against the force of
gravity, the weight being coupled to the object such that a weight
force acting on the weight causes the force acting in the direction
of the movement path.
4. The positioning system according to claim 1, further comprising
a retracting apparatus, which is configured to move the object
against the permanently acting force from the final position into
the initial position.
5. The positioning system according to claim 1, wherein the object
is a solar panel that is rotatably supported about a horizontal
axis of rotation.
6. The positioning system according to claim 5, further comprising
a frame mounted to the solar panel such that the center of gravity
of a unit comprising the frame and the solar panel falls outside
the axis of rotation.
7. The positioning system according to claim 6, wherein the frame
includes a boom extending perpendicular to the axis of rotation and
including a weight attached to the boom at a predetermined distance
from the axis of rotation.
8. The positioning system according to claim 6, wherein the brake
apparatus is configured to fix the position of the frame or of the
solar panel with respect to the axis of rotation.
9. The positioning system according to claim 6, wherein the frame
is furthermore rotatably supported with respect to a vertical axis
of rotation perpendicular to the horizontal direction, wherein the
preloading device includes a first fixed arm extending
perpendicular from the vertical axis and rotationally fixed with
respect to the frame and a second stationary arm, wherein the first
and the second arm are connected to each other via a spring.
10. The positioning system according to claim 9, wherein the brake
apparatus is further configured to fix the position of the frame or
the position of the solar panel with respect to the vertical axis
of rotation.
11. A method for controlled movement of an object from an initial
position to a final position via a plurality of intermediate
positions disposed along a movement path, the movement path
including an azimuthal component, the method comprising: exerting a
permanently acting force on the object in the direction of the
movement path, wherein the force includes a component acting in an
azimuthal direction; and fixing the object at an intermediate
position along the movement path using a brake apparatus.
12. The positioning system according to claim 1, wherein the object
includes a solar panel mounted on a frame for rotation about a
horizontal axis of rotation and the preloading device comprises a
boom extending from the frame and supporting a weight such that a
center of gravity of the system comprising the solar panel, the
frame, the weight and the boom does not lie on the axis of
rotation, a position of the weight on the boom being adjustable,
and the system further including at least one motor for shifting
the solar panel from the final position to the initial position
against the permanently acting force.
13. The positioning system according to claim 12, wherein the frame
is mounted for rotation about a vertical axis of rotation, and
wherein the preloading device further comprises a spring
rotationally biasing the frame in a first rotational direction, and
wherein the at least one motor is configured to rotate the frame in
a second rotational direction opposite the first rotational
direction.
14. The positioning system according to claim 1, wherein the object
includes a solar panel mounted on a frame for rotation about a
horizontal axis of rotation, wherein the frame is mounted for
rotation about a vertical axis of rotation, wherein the preloading
device comprises a spring rotationally biasing the frame in the
direction of movement, and the system further includes a motor for
shifting the solar panel from the final position to the initial
position against the permanently acting force.
15. The positioning system according to claim 14, wherein the
preloading device includes a first arm extending perpendicular from
a vertical portion of the frame and configured to rotate with the
vertical portion of the frame and a second arm rotationally fixed
relative to the vertical portion of the frame and a spring
connecting the first arm to the second arm.
16. A positioning system for moving, in a controlled manner, a
solar panel mounted on a frame from a beginning of a movement path
to an end of the movement path, the movement path having an
azimuthal component, the positioning system including: a spring
configured to rotate a vertical portion of the frame in a first
rotational direction; and a brake configured to selectively block
the rotation of the frame in the first rotational direction.
17. The positioning system according to claim 16, including a first
arm extending from a vertical portion of the frame and configured
to rotate with the vertical portion of the frame and a second arm
rotationally fixed relative to the vertical portion of the frame,
the spring connecting the first arm to the second arm.
18. The positioning system according to claim 16, further including
at least one motor for rotating the vertical portion of the frame
in a second direction opposite the first direction.
19. The positioning system according to claim 16, wherein the frame
is mounted for ration about a horizontal axis of rotation and
further comprising a boom extending from the frame and supporting a
weight such that a center of gravity of a system comprising the
solar panel, the frame, the weight and the boom does not lie on the
horizontal axis of rotation, a position of the weight on the boom
being adjustable, and the system further including at least one
motor for shifting the solar panel from the end of the movement
path to the beginning of the movement path and for rotating the
vertical portion of the frame in a second direction opposite the
first direction.
Description
[0001] Exemplary embodiments of the present invention are concerned
with a positioning system and with a method for positioning an
object.
[0002] Positioning systems, using which an object can be guided
from an initial position into a final position in a controlled
manner, are known in a variety of embodiments. For example, in a
variety of solar applications, panels including photovoltaic cells
or including mirrors/lenses for concentration of light at a common
focal point (such as, for example, with CPV, heliostat, Stirling
dish, solar trough, or linear Fresnel systems), which are all
summarized in the following under the term "solar panels," must be
oriented in a defined manner with respect to the sun, wherein
high-precision systems are required in order to be able to follow
the daily course of the sun. In particular in systems wherein the
incident light energy is to be concentrated at a point or a
designated surface, the positioning, i.e. the orientation of these
objects positioned using the positioning system must occur with the
highest possible precision. Therefore a play in the mechanics of
the system (backlash) is necessarily to be avoided.
[0003] Conventional positioning systems, which use linear actuators
or worm drives, have such a play as caused by the system. For
example, in some systems worm drives operate on gears in order to
effect a rotation of the panels. A play results, for example, since
during the driving the gears or worm gears are in contact with one
another via a flank, while after the driving or after the
switching-off of the propulsion a change of abutment of the flanks
can occur, for example due to a dynamic load acting on the panel.
Here in the case of solar applications, for example, even an
imprecision from 0.105.degree. to 0.135.degree. can lead to a
significant drop in efficiency and to an inefficiency of the entire
system. Furthermore, in such conventional systems the energy
required for operation of the positioning system is relatively high
since the drive motors must be energized during the positioning,
i.e. in the case of solar systems during the entire time of the
insolation, which leads to significant power losses.
[0004] Although in the just-now mentioned tracking systems or
positioning systems predominantly an orientation of the objects
moved using the positioning system is changed, equivalent
considerations also apply for positioning systems wherein the
object changes its position while it we transferred in a controlled
manner along a movement path from an initial position into a final
position. In these systems the object thus changes its position,
which is controlled by the positioning system, along a
3-dimensional locus in space. Here the same problems result
independent of whether the positioning system has one or more
degrees of freedom, i.e. whether the system can control one, two,
or three axes or one, two, or three spatial coordinates.
[0005] In view of the prior art known up to now, the need exists to
provide positioning systems which can be driven more
energy-efficiently and more flexibly than up to now.
[0006] According to some exemplary embodiments of the present
invention this is achieved by a positioning system for an object
including a preload apparatus connected to the object, which
preload apparatus exerts a force permanently acting on the object
in the direction of the movement path, which force has a component
acting in the azimuthal direction; the object is to be transferred
from an initial position into a final position in a controlled
manner along a movement path comprising an azimuthal rotation. In
order to be able to fix the object at a predetermined position or
in a predetermined orientation along the movement path, the
positioning system additionally has a brake apparatus which is
configured to fix the object at the predetermined position, i.e.
therefore to act against the permanently acting force such that the
object is fixed in the predetermined position at which the brake
apparatus is activated.
[0007] That is, the object is not actively accelerated or moved
along the movement path using a motor, but rather impinged on with
a force acting permanently in the direction of the movement path,
wherein the force at that position or orientation at which the
object is to be carried or in which the object is to be fixed is
compensated by the brake apparatus which fixes the object in its
current orientation or position. Compared to conventional systems
this leads to a significant energy savings in the positioning,
since electric motors possibly used in the system need not
permanently be subjected to voltage in order to suitably position
the object.
[0008] Moreover, the fixing of the position of the object along the
movement path increases the achievable positioning precision, since
an inherent intrinsic motor-driving play cannot affect the
positioning precision.
[0009] According to some exemplary embodiments the force acting in
the direction of the movement path is effected by a spring that can
be preloaded against the movement path so that the restoring force
of the elastic spring can be used to exert the permanently acting
force on the object. Here the spring force can be used, of course,
for a movement in one, two, or three axes or spatial coordinates.
This can be determined by appropriate selection of the geometric
boundary conditions. Generally speaking, in some exemplary
embodiments of the invention the force is effected by an element
that can store potential or mechanical energy, which can thus
change its state such that in an initial state the element has a
greater potential energy than in a final state.
[0010] According to some other exemplary embodiments the
permanently acting force is generated by a weight that is carried
against the force of gravity into a starting position before the
start of the positioning or of the moving of the object along the
movement path. The weight is coupled or connected to the object
such that the weight force acting on the weight causes the force in
the direction of the movement path. This approach can lead to a
significant energy savings since the mechanical device which causes
the force permanently acting on the object need only be preloaded
into the initial position at the start of a moving or of a
departing of a movement path. That is, an internal-combustion- or
electric-motor that is used to carry the preload apparatus into the
initial position need only be supplied or driven by electricity for
a short time.
[0011] Such a retracting apparatus, which transfers the object
against the permanently acting force from the final position into
the initial position and simultaneously carries the preload
apparatus into the initial position, can be, for example, an
electric motor, an internal combustion motor, a mechanism or motor
driven by alternative energies such as water power, solar power,
wind power, or the like.
[0012] According to some exemplary embodiments a positioning system
having one or two axes is used to adjust a solar panel to the daily
course of the position of the sun. This can significantly improve
the overall energy balance or the overall efficiency level of the
system due to the energy savings achievable with the
positioning.
[0013] According to some exemplary embodiments the positioning
system of the solar panel is uniaxial. That is, a solar panel
rotatably supported about an axis of rotation extending in the
horizontal direction is adjusted to the position of the sun using
the positioning system. Here according to one embodiment a frame
for the solar panel to be mounted on the frame is designed such
that its center of gravity, in particular if the solar panel has
already been installed on the frame, falls outside the axis of
rotation of the solar panel so that the permanent weight force
acting in the direction of the movement path is generated by the
geometry of the solar panel itself. The functionality of a preload
apparatus can thus be provided by the geometry of the frame or of
the solar panel itself.
[0014] In some exemplary embodiments the size of the force can be
varied such that the solar panel or its frame additionally includes
a boom extending perpendicular to the axis, on which a weight is
attached at a predetermined distance to the axis of rotation,
whereby the level of the permanently acting force can be adapted to
the conditions. In some exemplary embodiments the size of the force
can also be adapted to the size of the panel used by varying the
position of the additional weight on the boom, in particular the
distance to the axis of rotation.
[0015] In some exemplary embodiments the position of the solar
panel is adjusted not only in one axis, i.e., for example, the
elevation (height over the horizon), but also in a second axis, for
example the azimuth. In these exemplary embodiments the force
permanently acting in the movement direction thus also has a
component acting in the azimuthal direction. This component or the
force can be generated by a spring, for example, which is located
between two arms that are disposed on the one hand on a base and on
the other hand on a movable part of the positioning system. In
alternative exemplary embodiments a torsion spring can also be used
between the two components rotating relative to each other.
[0016] In both uni- and bi-axial positioning systems for solar
panels or for other objects whose orientation is to be changed in
two axes, the brake apparatus is configured to fix the position of
the object with respect to each of the axes of rotation, i.e. with
respect to the axial or the horizontal axis of rotation. That is,
the rotating of the object to be positioned is prevented with
respect to one or both axes and the object is thus fixed with
respect to these axes. Because of the separation of the drive and
the fixing of the object to be positioned, the mechanical play
inherent to the drive can be avoided due to the fixing relative to
the axes using the additional brake apparatus.
[0017] Some preferred exemplary embodiments of the present
invention are explained in more detail in the following with
reference to the accompanying Figures:
[0018] FIG. 1 shows a positioning system for a solar panel having a
movable axis; and
[0019] FIG. 2 shows a positioning system for a solar panel having a
second movable axis.
[0020] FIG. 1 shows an exemplary embodiment of the present
invention wherein a solar panel 2, for example, a photovoltaic
module or even a minor, can be oriented using a positioning system
such that this follows the changing position of the sun in the
course of the day.
[0021] The solar panel 2 is mounted on a frame 4 which is rotatably
supported, using an axis of rotation 8 extending in the horizontal
direction 6, with respect to a mast 14; the mast 14 is stationary
and extending in a vertical direction 10 to a base 12.
[0022] Furthermore a weight 18 is attached to a boom 16 extending
away from the axis of rotation 8, which weight 18 is movable from
the initial position shown in FIG. 1 of the weight 18 to a final
position wherein the weight 18 is located in the lowermost possible
position determined by the geometry. Due to the weight, a force
serving for positioning of the solar panel 2, i.e. acting in the
direction of the movement path of the solar panel 2, is permanently
exerted on the solar panel 2 or the frame 4 between these two
positions. In the exemplary embodiment shown in FIG. 1, the
"movement path" in the sense to be understood herein is thus
understood to be that change of the orientation or of the elevation
angle 20 between the surface normal of the solar panel 2 and of the
horizontal direction 6 that the solar panel 2 experiences with a
complete tilting about the axis 8. Generally speaking, the
"movement path" should be understood to be any change of a quantity
that describes an orientation or a location of an object and that
varies or is to be varied from the same with an adjusting or
controlled moving of an object.
[0023] Even at the start of the movement, i.e. in the initial
position shown in FIG. 1 of the solar panel 2, the weight force of
the weight 18 acts in the direction of the movement path so that
without a brake apparatus the solar panel 2 would perform an
unstopped movement from the initial position into the final
position. In order to prevent this, the exemplary embodiment in
FIG. 1 includes a brake apparatus 22 in the form of a brake, which
makes it possible to prevent the rotation of the panel 2 or of the
frame 4 with respect to the axis 8, which can thus fix the position
of the frame 4 or of the panel 2 with respect to the horizontal
axis of rotation 8.
[0024] As retracting apparatus 24 the exemplary embodiment of FIG.
1 includes an electric motor 26 which can exert a retracting force,
on an end of the boom facing away from the weight 18 via a diverted
cable pull, against the permanently acting force in order to be
able to carry the preload apparatus, which in this case is
comprised of the weight 18 on the boom 16, back into the initial
position shown in FIG. 1.
[0025] Although in the exemplary embodiment shown in FIG. 1 an
additional weight 18 serving for the generation of the permanently
acting force is provided, it is self-evident that in other
embodiments the preload apparatus, which exerts the permanently
acting force in the direction of the movement path on the solar
panel 2, can also be implemented in any other manner. For example,
this can be formed by the geometry of the frame 4 or of the solar
panel or the attaching of the solar panel 2 to the axis 8 itself.
If the geometry is designed, for example, such that the center of
gravity of the panel falls outside the axis 8, the required force
permanently acting in the direction of the movement path is already
exerted solely due to the geometric arrangement. Of course the
permanently acting force can also be exerted or effected in any
manner, for example using one or more springs, for example torsion
springs on the axis 8 or using weights formed in a different
manner, for example by a fluid-filled reservoir or the like.
[0026] Due to the brake apparatus 22 on the axis 8 it is ensured
that the positioning precision is very high since the drive and the
brake are embodied separate from each other and thus plays embodied
in the drive do not negatively influence the positioning precision.
In other words the solar panel 2 or the frame 4 itself is part of
the positioning system. In other words in the exemplary embodiment
shown in FIG. 1 the solar panel or the solar mirror is equipped
with a weight 18. Before the sun rises the weight 18 is lifted by
the electric motor 26 into the initial position shown in FIG. 1.
The system is thus "relaxed" overnight. The axis adjusting the
elevation 20 is thereby preloaded, i.e. due to the weight 18 a
force permanently acts thereon in the direction of the movement
path of the solar panel. In the course of the day the weight 18 is
continuously tilted downward in a manner controlled by the brake
apparatus 22 whereby the elevation angle 20 of the solar panel 20
changes so that this always has an optimal orientation with respect
to the current position of the sun. This can be determined, for
example, using the spatial coordinates of the positioning system,
which in turn can be determined via a GPS system, astronomical
calendars, Hall sensors which indicate the current position of the
axis, and a built-in reference point, so that the adjustment can
optimally succeed at any point in time. Using modern energy storage
and intelligent software control it is ensured that at any time the
emergency positioning (panel horizontal) can be moved to. The
controlling recognizes whether the weight must be lifted up or
merely lowered.
[0027] In the evening the weight 18 has arrived in its final
position at the lower end of the mast 14. If in the daytime storms
or other weather conditions affecting the device occur, the solar
panel 2 can of course be artificially moved, even before the end of
the day, into an emergency position wherein the panel is situated
horizontally. Before sunrise the weight is pulled back into the
initial position shown in FIG. 1, for which purpose the retracting
apparatus 24 is used. According to some exemplary embodiments the
current generated by the solar panel itself, for example, can be
used for this purpose without impairing the efficiency of the solar
panel during the day such that current must be applied permanently
to the positioning motors. For this reason in some exemplary
embodiments a self-locking brake is also used as brake apparatus
22, i.e. a brake wherein a control current is only need for
releasing the brake, so that most of the time no power loss occurs
in the assembly. In other words, some exemplary embodiments are
based on the fact that the center of gravity of the frame or the
common center of gravity of the solar panel and of the frame
deliberately lies outside the axis so that the moment thereby
effected can be used for driving.
[0028] FIG. 2 shows a further exemplary embodiment of the
invention, based on FIG. 1, wherein an adjusting of the solar panel
2 (tracking) also occurs in an azimuthal direction, i.e. the
movement path also has a component that corresponds to an azimuthal
rotation, i.e. a change of an azimuthal angle 28.
[0029] In order to make this possible, in the exemplary embodiment
shown in FIG. 2 the mast 14 is rotatably supported with respect to
the base 12, wherein the preload apparatus additionally includes a
first arm 30 which is rigidly connected to the mast 14 and thus
also to the frame 4 or the panel 2 with respect to the azimuthal
direction. The positioning system further includes a second arm 32
which is rigidly connected in a stationary manner, i.e., for
example, to the base 12. Using a bending spring 34 a permanently
acting force is generated in the azimuthal direction 28 between the
first arm 30 and the second arm 32, i.e. a force that permanently
acts along the azimuthal components of the movement path of the
solar panel. In order to make possible the controlled movement, the
assembly of FIG. 2 furthermore includes a further brake apparatus,
which acts between the mast 14 and the base 12, so that using the
further brake apparatus the position of the frame can be fixed with
respect to the vertical axis of rotation. It is self-evident that
any other device can also be used for second, and controllably
movable, axis shown in FIG. 2, in order to achieve the continuously
acting force in the direction of the movement path. This can be,
for example, any other form of spring, for example a torsion
spring, between the mast 14 and the base 12.
[0030] Although in the previous exemplary embodiment for a uniaxial
adjusting only the adjusting of the elevation has been shown,
according to further uniaxial exemplary embodiments only the
azimuth can be adjusted using a preload apparatus.
[0031] Although in the previous two exemplary embodiments the
inventive concept for has mainly been illustrated using a tracking
system for a solar panel 2, it is self-evident that in further
exemplary embodiments other positioning systems can also make use
of the inventive teachings. Among these of course also those
wherein not only the orientation of an object is changed, but also
its geometric location, wherein, i.e., it moves in a controlled
manner along a predetermined trajectory in space using the
positioning system for a moving object.
REFERENCE NUMBER LIST
[0032] 2 Solar panel
[0033] 4 Frame
[0034] 6 Horizontal direction
[0035] 8 Axis of rotation
[0036] 10 Vertical direction
[0037] 12 Base
[0038] 14 Mast
[0039] 16 Boom
[0040] 18 Weight
[0041] 20 Elevation angle
[0042] 22 Brake apparatus
[0043] 24 Retracting apparatus
[0044] 26 Electric motor
[0045] 28 Azimuth angle
[0046] 30 First arm
[0047] 32 Second arm
[0048] 34 Bending spring
* * * * *