US20100192942A1

US20100192942A1 - Solar tracking system

Info

Publication number: US20100192942A1
Application number: US12/678,523
Authority: US
Inventors: Colin Jones
Original assignee: Global Product Design Pty Ltd
Current assignee: Global Product Design Pty Ltd
Priority date: 2007-09-24
Filing date: 2008-05-30
Publication date: 2010-08-05
Also published as: WO2009039556A1; AU2008303046A1

Abstract

A solar tracking system enables an array of solar panels to track a path of the sun. The system includes a main support arm (205) having a hub end and a distal end. A rotatable main hub (220) is attached to the hub end of the main support arm (205). A support frame (215) is rotatably attached to the distal end of the main support arm (205). A tie-rod (210, 610) includes a swivel end and a frame end, and the swivel end is rotatably positioned adjacent to the main hub (220). The frame end of the tie-rod (210, 610) is connected to the support frame (215) above the distal end of the main support arm (205), such that rotation of the main hub (220) causes a vertical orientation of the support frame (215) to change.

Description

FIELD OF THE INVENTION

The present invention relates to mechanisms for tracking movement of the sun. In particular, although not exclusively, the invention relates to a system for maintaining one or more solar panels facing the sun during the day to improve solar energy collection efficiency.

BACKGROUND TO THE INVENTION

Global warming and the increase in greenhouse gas emissions have resulted in an increased public awareness of solar energy use. Further, advanced technology has enabled the use of solar energy in residential and small scale commercial buildings to become more economically feasible. In particular, the costs of photovoltaic panels have decreased while operating efficiencies of such panels have significantly increased.
Other technologies associated with solar panels have also advanced. For example, various companies have attempted to improve mounting and tracking capabilities of solar panels. It is well known that when a solar panel is enabled to track the movement of the sun from east to west—so that a normal vector extending from a plane of the solar panel always remains pointed at the sun—the amount of energy collected by the solar panel can be greatly improved. Energy collection efficiency associated with a tracking solar panel can be almost 60% higher than an efficiency of a similar panel that is simply mounted in a static position. A solar panel that tracks the sun generally must be pivoted about at least two axes: a first axis that pivots horizontally from east to west; and a second axis that pivots vertically upward from the horizon during the morning and downward toward the horizon during the afternoon.
The prior art therefore includes numerous devices and systems designed to enable a solar panel to track the movement of the sun. For example, such prior art includes the following:
U.S. Pat. No. 4,295,621 to Siryj, B, filed Mar. 18, 1980, titled “Solar Tracking Apparatus”, discloses a solar array support member pivotally secured to the upper end of a support post for rotation about a horizontal axis. The support post is driven about a vertical axis. A motor and pulley system drive a rotating disc secured to the post to set the elevation position of the support member. A second motor and pulley system drive the post about its vertical axis with respect to a base.
U.S. Pat. No. 4,368,962 to Hultberg, D, filed Jan. 30, 1981, titled “Solar Tracking Apparatus and System”, discloses an apparatus comprising a pair of concentric shafts oriented parallel to the earth's rotational axis with one shaft being rotated by a motor at one revolution per day, so that a yoke rigidly attached to the shaft will follow the diurnal motion of the sun. A second concentric shaft is rotated at a rate relative to the first shaft and, by means of a spherical four-bar linkage, automatically produces a rotational oscillation of a support or gimbal mounted on the yoke equal to the yearly declination of the sun.
International application PCT/DE94/00612 to Berger, A., filed Jun. 1, 1994, titled “Sun-Following Device”, discloses the use of an energy-storing counterweight in a base of a first solar panel that is hydraulically linked to an energy-storing counterweight in a base of a second solar panel. The counterweights are attached to linkage associated with their respective solar panels to enable movement of the solar panels.
U.S. Pat. No. 6,848,442 to Haber, M. filed Jan. 29, 2001, titled “Solar Panel Tilt Mechanism”, discloses a tilt mechanism associated with an array of solar panels whereby effort required to tilt the solar panels is reduced by appropriate placement of first and second tilt axes with respect to the centre of mass and/or centre of pressure of the panels due to wind.
U.S. Pat. No. 6,443,145 to Buron, V. et al., filed Aug. 24, 2001, titled “Solar Seeker”, discloses a solar panel carriage assembly, a mounting assembly, and a travel assembly to enable a solar panel to automatically track the sun.
However, the prior art devices and systems described above generally require either complex components such as multiple motors or hydraulic systems, non-durable components such as numerous small gearing mechanisms, or single-panel specific components that cannot be easily linked to move multiple panels in a solar panel array. Further, motion of some prior art sun tracking systems is restricted so that only a partial path of the sun when above the horizon can be tracked. There is therefore a need for an improved solar tracking system that overcomes one or more of these disadvantages.

OBJECTS OF THE INVENTION

Therefore, an object of some embodiments of the present invention is to overcome or alleviate one or more limitations of the prior art, including providing an improved solar tracking system.
Another object of some embodiments of the present invention is to provide an improved solar tracking system that includes durable and robust components that enables a long, low-maintenance service life.
Another object of some embodiments of the present invention is to provide an improved solar tracking system that can move multiple solar panels arranged in an array.
Another object of some embodiments of the present invention is to provide an improved solar tracking system that can move multiple solar panels through multiple degrees of freedom using only a single drive mechanism.
A further object of some embodiments of the present invention is to provide an improved solar tracking system that enables attached solar panels to deflect in high winds, thereby reducing wind-induced forces on associated mounting hardware.
Still another object of some embodiments of the present invention is to provide an improved solar tracking system that enables a solar panel to be positioned fully vertically to point directly at the horizon, thus enabling increased energy collection efficiency during the early morning and late afternoon. Still further objects will be evident from the following detailed description.

SUMMARY OF THE INVENTION

According to one aspect, the present invention is a solar tracking system, comprising:
a main support arm having a hub end and a distal end;
a rotatable main hub attached to the hub end of the main support arm;
a support frame rotatably attached to the distal end of the main support arm; and
a tie-rod having a swivel end and a frame end, the swivel end rotatably positioned adjacent to the main hub and the frame end connected to the support frame above the distal end of the main support arm, whereby rotation of the main hub causes a vertical orientation of the support frame to change.
Optionally, the tie-rod comprises a spring mechanism.
Optionally, the swivel end of the tie-rod is connected to a tie-rod bracket extending from a centre post of the main hub, wherein the main hub is rotatable relative to the centre post.
Optionally, the support frame comprises a solar panel support frame.
Optionally, the main hub comprises a pulley or sprocket for causing rotation of the main hub.
Optionally, the solar tracking system further comprises an array including a plurality of main hubs supporting a plurality of support frames, wherein each main hub in the plurality of main hubs is attached to a central support rail.
Optionally, the swivel end of the tie-rod is connected to a rear pillar mount.
Optionally, the solar tracking system further comprises a clamping sleeve for attaching the rear pillar mount to a support rail, and another clamping sleeve for attaching the main hub to the support rail.
Optionally, a distance between the main hub and the rear pillar mount is adjustable.
Optionally, the solar tracking system further comprises a ball joint at the swivel end of the tie-rod and a ball joint at the frame end of the tie-rod.
Optionally, a length of the tie-rod is adjustable.
Optionally, a distance between the main hub and the rear pillar mount is adjustable.
Optionally, the solar tracking system further comprises an electric motor to power a drive cable or sprocket engaging the main hub.
Optionally, the electric motor is controlled by a timer or a position sensor.
Optionally, the main support arm, the rotatable main hub, the support frame, and the tie-rod define a pivotable base mechanism.

BRIEF DESCRIPTION OF THE DRAWINGS

To assist in understanding the invention and to enable a person skilled in the art to put the invention into practical effect, preferred embodiments of the invention are described below by way of example only with reference to the accompanying drawings, in which:

FIG. 1 is a diagram illustrating a top perspective view of a solar panel array, including a plurality of pivotable base mechanisms, mounted on a roof of a building such as a house in the southern hemisphere, according to some embodiments of the present invention.

FIG. 2 is a diagram illustrating a close-up, top view of a pivotable base mechanism of FIG. 1.

FIG. 3 is a diagram illustrating a close-up, side view of a pivotable base mechanism of FIG. 1.

FIG. 4 is a diagram illustrating a close-up, top view of a pivotable base mechanism aligned in the same orientation shown in FIG. 3.

FIG. 5 is a diagram illustrating a close-up, rear view of a pivotable base mechanism of FIG. 1.

FIG. 6 is a diagram illustrating a close-up, side view of a pivotable base mechanism, according to some alternative embodiments of the present invention.

FIG. 7 is a diagram illustrating a close-up, partial cut-away view of a linear spring gas strut tie-rod, according to some embodiments of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Embodiments of the present invention comprise a solar tracking system. Elements of the invention are illustrated in concise outline form in the drawings, showing only those specific details that are necessary to understanding the embodiments of the present invention, but so as not to clutter the disclosure with excessive detail that will be obvious to those of ordinary skill in the art in light of the present description.
In this patent specification, adjectives such as first and second, up and down, above and below, top and bottom, etc., are used solely to define one element or method step from another element or method step without necessarily requiring a specific relative position or sequence that is described by the adjectives. Words such as “comprises” or “includes” are not used to define an exclusive set of elements or method steps. Rather, such words merely define a minimum set of elements or method steps included in a particular embodiment of the present invention.
Referring to FIG. 1, a diagram illustrates a top perspective view of a solar panel array 100 mounted on a roof 105 of a building such as a house in the southern hemisphere, according to some embodiments of the present invention. The solar panel array 100 includes five solar panels 110-n (i.e., 110-1 through 110-5) that are shown pivoted to a near-vertical position facing to the East. As shown, the solar panels 110-n are ready to receive sunlight from the north-eastern horizon during the early morning. Each solar panel 110-n is attached to a pivotable base mechanism 115-n that enables the solar panels 110-n to pivot simultaneously about both a horizontal and a vertical axis to track the position of the sun from when, for example, it rises in the Northeast to when it sets in the Northwest during winter in the southern hemisphere.
A drive cable 120 is shown engaging each of the pivotable base mechanisms 115-n. A cable actuator 125 is also connected to the drive cable 120 and powers movement of the drive cable 120. The cable actuator 125 includes an electric motor 130 and a controller and can be mounted, for example, on the roof 105 or on one of a plurality of support brackets 145.
A central support rail in the form of a central support pipe 140, such as a standard steel plumbing pipe, is mounted to the roof 105 using the support brackets 145, and extends beneath each pivotable base mechanism 115-n. Each pivotable base mechanism 115-n is then clamped to the central support pipe 140. A light sensing electronic eye 150, which are well known by those having ordinary skill in the art, can be mounted on one of the solar panels 110-n, such as on the solar panel 110-1, to enable automatic determination of a present position of the sun. Also, a timer can be mounted on one of the solar panels 110-n to time movement of the pivotable base mechanisms 115-n. The electronic eye 150 and the timer can be operatively connected to the controller 135 using wired or wireless connection means.
Referring to FIG. 2, a diagram illustrates a close-up, top view of one of the pivotable base mechanisms 115-n, according to some embodiments of the present invention. The pivotable base mechanisms 115-n each include a main support arm 205, a tie-rod 210, and a solar panel support frame 215. For clarity, in FIG. 2 and all subsequent figures the solar panel 110-n is removed from the solar panel support frame 215 and is not shown. The main support arm 205 is attached at a hub end to a main hub 220, which is bolted to the central support pipe 140. A distal end of the main support arm 205 is attached to the solar panel support frame 215. The main support arm 205 thus, in use, supports the weight of the solar panel support frame 215 and an attached solar panel 110-n, and can rotate relative to the central support pipe 140. The drive cable 120 is wrapped around and engages a pulley 225 attached to the main hub 220, and thus linear movement of the drive cable 120 causes rotational movements of the main hub 220 and the main support arm 205. Further, bearings 230 at the distal end of the main support arm 205 enable pivoting of the solar panel support frame 215 between vertical and horizontal orientations.
A first ball joint 235 at a swivel end of the tie-rod 210 is connected to a distal end of a tie-rod bracket 239 that is fixed relative to the central support pipe 140. A second ball joint 240 at a frame end of the tie-rod 210 is bolted to the solar panel support frame 215 above the bearings 230. Frame flanges 245 are used to bolt a solar panel 110-n to the solar panel support frame 215.
As described in more detail below, the tie-rod 210 may comprise a linear spring to enable the solar panels 110-n to lean over under high winds, and thus reduce high wind forces on the solar panel array 100, which forces otherwise could potentially damage the solar panels 110-n, the pivotable base mechanisms 115-n, or roofing structures to which the support brackets 145 are attached.
Referring to FIG. 3, a diagram illustrates a close-up, side view of one of the pivotable base mechanisms 115-n, according to some embodiments of the present invention. The pivotable base mechanism 115-n is shown rotated relative to the central support pipe 140 so that the main support arm 205 and the tie-rod 210 are both parallel to each other and parallel to the central support pipe 140 in a vertical plane. Such rotation away from the position shown in FIG. 2 causes a distance between the first ball joint 235 and the bearings 230 at the distal end of the main support arm 205 to increase. That in turn causes the second ball joint 240 to pull on a bracket 300 of the solar panel support frame 215 and pivot the solar panel support frame 215 backward about the bearings 230 and to a position, as shown, about 45 degrees between the vertical and horizontal.
Shown in a partial cut-away view of the main hub 220, a main hub bolt 305 secures the tie-rod bracket 239 above the main hub 220, which enables the tie-rod 210 to swing over the main hub 220. The main hub bolt 305 bolts directly to a hub post 325. A clamping sleeve 320 welded to the hub post 325 is used to clamp the hub post 325 to the central support pipe 140 using bolts 330. Bearings 335 inside the main hub 220 enable the main support arm 205 to rotate relative to the hub post 325; whereas the tie-rod bracket 239 is rigidly connected to a clamping collet 336 that fits over the hub post 325. The tie-rod bracket 239 thus remains generally parallel to the central support pipe 140 in a vertical plane.
A distance between the main hub 220 and the swivel end of the tie-rod 210 thus remains substantially constant when the main hub 220 rotates relative to the central support pipe 140.
The clamping collet 336 also secures the bearings 335 to the hub post 325. The clamping collet 336 is driven between a bearing radius corner 338 and the hub post 325 and prevents the tie-rod bracket 239 from rotating relative to the central support pipe 140. Releasing the main hub bolt 305 enables the tie-rod bracket 239 to be rotated around the hub post 325 to locate, for example, a North position in Southern hemisphere locations.
The orientation of the pivotable base mechanism 115-n shown in FIG. 3 is thus used, for example, around noon when the sun is highest in the sky and is shining from the North (in the Southern hemisphere). Depending on the season and the latitudinal position of the pivotable base mechanism 115-n, increasing an effective length of the bracket 300 (e.g., by loosening a bolt through the second ball joint 240 and sliding the bolt in a slot 337 in the bracket 300 toward a distal end of the bracket 300) will cause the solar panel support frame 215 to assume a more vertical orientation. For example, at equatorial latitudes where the sun is nearly directly over-head at noon, the second ball joint 240 should be positioned in the slot 337 so that the solar panel support frame 215 approaches horizontal when the tie-rod 210 is parallel to the main support arm 205; whereas in high latitude regions where the sun remains at a low azimuth at noon, the second ball joint 240 should be positioned in the slot 337 to provide a greater effective length of the bracket 300, which causes the solar panel support frame 215 to assume a more vertical orientation that is normal to the sun.
Further, finer seasonal adjustments of the horizontal orientation of the solar panel support frame 215 can be made by rotating a nut 350 on the tie-rod 210, which extends or reduces an effective length of the tie rod 210.
Referring to FIG. 4, a diagram illustrates a close-up, top view of one of the pivotable base mechanisms 115-n aligned in the same orientation shown in FIG. 3, according to some embodiments of the present invention. This illustrates the substantially horizontal orientation of the solar panel support frame 215 compared to the substantially vertical orientation of the solar panel support frame 215 shown in FIG. 2.
Referring to FIG. 5, a diagram illustrates a close-up, rear view of one of the pivotable base mechanisms 115-n, according to some embodiments of the present invention. The solar panel support frame 215 is illustrated in a substantially vertical orientation facing to the East (similar to the orientation shown in FIGS. 1 and 2). An outline image 500 using broken lines then illustrates a comparable substantially vertical orientation of the solar panel support frame 215 facing to the West.
The solar panel array 100 is therefore enabled to cause each solar panel 110-n and an associated solar panel support frame 215 to obtain a substantially vertical orientation in the morning facing the sun on the horizon in the East. Then, powered by a linear motion of the drive cable 120 using the cable actuator 125, each solar panel support frame 215 rotates slowly to the North as the main hub 220 rotates, following the arc of the sun during the morning. Simultaneously, each solar panel support frame 215 pivots back slowly away from the vertical as the sun rises higher above the horizon. Thus normal vectors extending away from each solar panel 110-n remain pointing directly at the sun. Around noon, each solar panel support frame 215 is positioned in its most horizontal orientation (as shown in FIGS. 3 and 4), as the sun is then highest in the sky. During the afternoon, the main hub 220 continues to rotate and each solar panel support frame 215 again rises toward a vertical orientation, now facing the West as the sun sets. As will be understood by those having ordinary skill in the art, the controller 135 can be programmed to move the cable actuator 125 according to a simple timer or according to a position sensor such as the electronic eye 150.
A length of the tie-bar 210 and/or an effective length of the bracket 300, as discussed above, can be periodically and incrementally adjusted to account for seasonal changes in the path of the sun. For example, at the beginning of a season a configuration of a pivotable base mechanism 115-n can be set based on a known arc of the sun during the middle of that season. Alternatively, a pivotable base mechanism 115-n can be fixed at a single configuration based on an average annual arc of the sun.
Referring to FIG. 6, a diagram illustrates a close-up, side view of a pivotable base mechanism 615-n, according to some alternative embodiments of the present invention. Similar to the pivotable base mechanisms 115-n, the pivotable base mechanism 615-n is shown rotated relative to the central support pipe 140 so that the main support arm 205 and a tie-rod 610 are both parallel to each other and parallel to the central support pipe 140 in a vertical plane. A rear pillar mount 605 supports a first ball joint 607 above a main hub 620, which enables the tie-rod 610 to swing over the main hub 620. A second clamping sleeve 612 at a base of the rear pillar mount 605 is used to clamp the rear pillar mount 605 to the central support pipe 140 using bolts 617. Similarly, a clamping sleeve 320 at a base of a hub post 625 of the main hub 620 is used to clamp the hub post 625 to the central support pipe 140 using bolts 330. Thus, according to this alternative embodiment, the tie-rod 610 is connected to the central support pipe 140 independently of the main hub 620. The embodiment shown in FIG. 6 thus can be distinguished from the embodiment shown in FIG. 3, where the tie-rod 210 is shown connected through the main hub 220 to the single clamping sleeve 320.
Shown in a partial cut-away view of the main hub 620, bearings 635 inside the main hub 620 enable a main support arm 205 to rotate relative to a hub post 625. Neglecting any minor springing or bending motion of the rear pillar mount 605, a distance between the main hub 620 and the swivel end of the tie-rod 610 remains substantially constant when the main hub 620 rotates relative to the central support pipe 140.
The orientation of the pivotable base mechanism 615-n shown in FIG. 6 is used, for example, around noon when the sun is highest in the sky and is shining from the North (when the pivotable base mechanism 615-n is employed in the southern hemisphere). Depending on the season and the latitudinal position of the pivotable base mechanism 615-n, increasing the distance between the rear pillar mount 605 and the main hub 620 (e.g., by sliding the second clamping sleeve 612 along the central support pipe 140 away from the clamping sleeve 320) will cause the solar panel support frame 215 to assume a more horizontal orientation. For example, at equatorial latitudes where the sun is nearly directly over-head at noon, the rear pillar mount 605 should be positioned so that the solar panel support frame 215 is nearly horizontal when the tie-rod 610 is parallel to the main support arm 205.
Referring to FIG. 7, a diagram illustrates a close-up, partial cut-away view of the tie- rod 210 or 610, according to some embodiments of the present invention. As described above, the tie- rod 210 or 610 can comprise a linear spring to enable a length of the tie- rod 210 or 610 to increase or decrease when a high wind force is applied to a solar panel 110-n. Such changes in the length of the tie- rod 210 or 610 thus enable a solar panel 110-n to lean over in high wind and significantly reduce potentially damaging wind forces applied to the solar panel 110-n.
As shown, the tie- rod 210 or 610 comprises a damped, two-way, linear spring gas strut 705 bolted into a mounting pipe 710. The mounting pipe 710 is then bolted to the tie-rod bracket 239 or to the rear pillar mount 605 through the first ball joint 235 or 607, respectively, depending on various embodiments of the present invention. The gas strut 705 includes a first compression chamber 715 in which a gas is compressed when a tensile force is applied to the strut 705, and a second compression chamber 720 in which a gas is compressed when a compressive force is applied to the strut 705. A wear ring 725 slides against the strut 705 when the strut 705 moves in and out of the mounting pipe 710.
Those skilled in the art will appreciate that various embodiments of the present invention can include other types of tie-rods, such as simple rigid tie-rods and tie-rods incorporating various types of spring mechanisms such as damped mechanical coil springs and undamped springs.
Various other embodiments and modifications of the present invention are also enabled by the present disclosure. For example, those skilled in the art will readily appreciate that various reconfigurations of the embodiments shown in FIGS. 1 through 7 are possible, while still accomplishing the features and functions of the solar tracking system of the present invention. For example, various relative dimensions of the components of the solar panel array 100 can be changed, and various alternative types of components can be substituted. For example, various different fastener and connection mechanisms, including welding and unitary construction of components, can be employed to achieve the functionality enabled by the teachings of the present invention.
As will be understood by those having ordinary skill in the art, the solar panel array 100 also can be mounted in various locations besides rooftops. For example, the array 100 can be mounted directly on the ground, on various stationary structures, or on vehicles, and can be scaled up or down to support different size solar panels.
Further, the embodiments illustrated in the drawings comprise an array of multiple solar panels 110-n. However, those having ordinary skill in the art will readily appreciate that the teachings of the present invention also enable construction and use of a single pivotable base mechanism 115-n to track the path of the sun. In such an embodiment, the pulley 225 can be replaced by a direct-drive mechanism such as a motorized sprocket.
The above description of various embodiments of the present invention is provided for purposes of description to one of ordinary skill in the related art. It is not intended to be exhaustive or to limit the invention to a single disclosed embodiment. As mentioned above, numerous alternatives and variations to the present invention will be apparent to those skilled in the art of the above teaching. Accordingly, while some alternative embodiments have been discussed specifically, other embodiments will be apparent or relatively easily developed by those of ordinary skill in the art. This patent specification is intended to embrace all alternatives, modifications and variations of the present invention that have been discussed herein, and other embodiments that fall within the spirit and scope of the above described invention.

Claims

1. A solar tracking system, comprising:

a main support arm having a hub end and a distal end;

a rotatable main hub attached to the hub end of the main support arm;

a support frame rotatably attached to the distal end of the main support arm; and

a tie-rod having a swivel end and a frame end, the swivel end rotatably positioned adjacent to the main hub and the frame end connected to the support frame above the distal end of the main support arm, whereby rotation of the main hub causes a vertical orientation of the support frame to change.

2. The solar tracking system according to claim 1, wherein the tie-rod comprises a spring mechanism.

3. The solar tracking system according to claim 1, wherein the swivel end of the tie-rod is connected to tie-rod bracket extending from a centre post of the main hub, wherein the main hub is rotatable relative to the centre post.

4. The solar tracking system according to claim 1, wherein the support frame comprises a solar panel support frame.

5. The solar tracking system according to claim 1, wherein the main hub comprises a pulley or sprocket for causing rotation of the main hub.

6. The solar tracking system according to claim 1, wherein the solar tracking system further comprises an array including a plurality of main hubs supporting a plurality of support frames, wherein each main hub in the plurality of main hubs is attached to a central support rail.

7. The solar tracking system according to claim 1, wherein the swivel end of the tie-rod is connected to a rear pillar mount.

8. The solar tracking system according to claim 7, wherein the solar tracking system further comprises a clamping sleeve for attaching the rear pillar mount to a support rail, and another clamping sleeve for attaching the main hub to the support rail.

9. The solar tracking system according to claim 7, wherein a distance between the main hub and the rear pillar mount is adjustable.

10. The solar tracking system according to claim 1, wherein the solar tracking system further comprises a ball joint at the swivel end of the tie-rod and a ball joint at the frame end of the tie-rod.

11. The solar tracking system according to claim 1, wherein a length of the tie-rod is adjustable.

12. The solar tracking system according to claim 1, wherein the solar tracking system further comprises an electric motor to power a drive cable or sprocket engaging the main hub.

13. The solar tracking system according to claim 1, wherein the electric motor is controlled by a timer or a position sensor.

14. The solar tracking system according to claim 1, wherein the main support arm, the rotatable main hub, the support frame, and the tie-rod define a pivotable base mechanism.