POSITIONING SYSTEM AND METHOD FOR POSITIONING AN ARTICLE

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.

Exemplary embodiments of the present invention are concerned with a positioning system and with a method for positioning an object.

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.

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° to 0.135° 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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

FIG. 1shows an exemplary embodiment of the present invention wherein a solar panel2, 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.

The solar panel2is mounted on a frame4which is rotatably supported, using an axis of rotation8extending in the horizontal direction6, with respect to a mast14; the mast14is stationary and extending in a vertical direction10to a base12.

Furthermore a weight18is attached to a boom16extending away from the axis of rotation8, which weight18is movable from the initial position shown inFIG. 1of the weight18to a final position wherein the weight18is located in the lowermost possible position determined by the geometry. Due to the weight, a force serving for positioning of the solar panel2, i.e. acting in the direction of the movement path of the solar panel2, is permanently exerted on the solar panel2or the frame4between these two positions. In the exemplary embodiment shown inFIG. 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 angle20between the surface normal of the solar panel2and of the horizontal direction6that the solar panel2experiences with a complete tilting about the axis8. 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.

Even at the start of the movement, i.e. in the initial position shown inFIG. 1of the solar panel2, the weight force of the weight18acts in the direction of the movement path so that without a brake apparatus the solar panel2would perform an unstopped movement from the initial position into the final position. In order to prevent this, the exemplary embodiment inFIG. 1includes a brake apparatus22in the form of a brake, which makes it possible to prevent the rotation of the panel2or of the frame4with respect to the axis8, which can thus fix the position of the frame4or of the panel2with respect to the horizontal axis of rotation8.

As retracting apparatus24the exemplary embodiment ofFIG. 1includes an electric motor26which can exert a retracting force, on an end of the boom facing away from the weight18via 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 weight18on the boom16, back into the initial position shown inFIG. 1.

Although in the exemplary embodiment shown inFIG. 1an additional weight18serving 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 panel2, can also be implemented in any other manner. For example, this can be formed by the geometry of the frame4or of the solar panel or the attaching of the solar panel2to the axis8itself. If the geometry is designed, for example, such that the center of gravity of the panel falls outside the axis8, 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 axis8or using weights formed in a different manner, for example by a fluid-filled reservoir or the like.

Due to the brake apparatus22on the axis8it 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 panel2or the frame4itself is part of the positioning system. In other words in the exemplary embodiment shown inFIG. 1the solar panel or the solar mirror is equipped with a weight18. Before the sun rises the weight18is lifted by the electric motor26into the initial position shown inFIG. 1. The system is thus “relaxed” overnight. The axis adjusting the elevation20is thereby preloaded, i.e. due to the weight18a force permanently acts thereon in the direction of the movement path of the solar panel. In the course of the day the weight18is continuously tilted downward in a manner controlled by the brake apparatus22whereby the elevation angle20of the solar panel20changes 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.

In the evening the weight18has arrived in its final position at the lower end of the mast14. If in the daytime storms or other weather conditions affecting the device occur, the solar panel2can 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 inFIG. 1, for which purpose the retracting apparatus24is 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 apparatus22, 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.

FIG. 2shows a further exemplary embodiment of the invention, based onFIG. 1, wherein an adjusting of the solar panel2(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 angle28.

In order to make this possible, in the exemplary embodiment shown inFIG. 2the mast14is rotatably supported with respect to the base12, wherein the preload apparatus additionally includes a first arm30which is rigidly connected to the mast14and thus also to the frame4or the panel2with respect to the azimuthal direction. The positioning system further includes a second arm32which is rigidly connected in a stationary manner, i.e., for example, to the base12. Using a bending spring34a permanently acting force is generated in the azimuthal direction28between the first arm30and the second arm32, 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 ofFIG. 2furthermore includes a further brake apparatus, which acts between the mast14and the base12, 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 inFIG. 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 mast14and the base12.

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.

Although in the previous two exemplary embodiments the inventive concept for has mainly been illustrated using a tracking system for a solar panel2, 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

8Axis of rotation