Method of determining orientation of a telescope

An automatic telescope (10) capable of determining an orientation without requiring input from a user or any external source. The telescope (10) preferably includes a database (22) to store astronomical information, a processor (24) to control a drive mechanism (18), a vision device (30) to sense bright stars, and a motion sensor (32) to generate a motion signal. When the vision device (30) is slewed from alignment with a first bright star to a second bright star, the motion signal is preferably representative of a measured angle between the first and second bright stars. This process is preferably repeated for several bright stars to generate several measured angles. The processor (24) can then use the measured angles to identify the bright stars and determine the orientation of the telescope (10).

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to telescopes. More particularly, the present invention relates to an automatic telescope that can align itself in order to view a specified star.

2. Description of Prior Art

Many telescopes are capable of finding and tracking stars and other celestial bodies. However, these telescopes must be initially oriented and re-oriented each time they are moved. Therefore, users are typically required to provide such telescopes with orientation information, such as an altitude angle and an azimuth angle. Unfortunately, many users are not familiar with or do not want to be bothered with providing such information.

Additionally, such telescopes typically only have small hard-to-use interfaces, such as handheld remote controls. While these remote controls are adequate for some purposes, they can be difficult to use, further increasing the inconvenience of providing orientation information.

Accordingly, there is a need for an improved automatic telescope that overcomes the limitations of the prior art.

SUMMARY OF THE INVENTION

The present invention overcomes the above-identified problems and provides a distinct advance in the art of telescopes. More particularly, the present invention provides an automatic telescope capable of determining an orientation without requiring input from a user or an external source. Additionally, the telescope may automatically align itself with virtually any star, planet, or other celestial object specified by the user. The telescope broadly comprises an optical telescopic tube for magnifying distant objects, a base for supporting the tube, a cradle for securing the tube to the base, a drive mechanism for moving the tube with respect to the base, and a control unit to control the drive mechanism.

The control unit preferably includes a database to store astronomical information and a processor to align the tube with the specified star using the drive mechanism. The database preferably includes information about stars, planets, and other celestial objects, such as nebulae. The information preferably includes location information and details relating to each celestial object, such as position, size, magnitude, type of object, and identification information.

The control unit also preferably includes a vision device to electronically sense bright stars and a motion sensor to sense motion of the tube of the telescope. The vision device is preferably securely aligned with the tube and may be secured to the tube or the cradle. The vision device preferably generates a vision signal representative of an image in the vision device's field of view. Therefore, when the tube and the vision device are pointed at a first bright star, the vision signal is representative of the first bright star.

Similarly, the motion sensor is preferably securely aligned with the tube and may be secured to the tube or the cradle. The motion sensor preferably generates a motion signal representative of changes in altitude and azimuth angles of the tube. Therefore, as the tube is slewed from alignment with the first bright star to a second bright star, the motion signal is preferably representative of that motion comprising the changes in the altitude and azimuth angles between the first bright star and the second bright star. The changes in the altitude and azimuth angles constitute a measured angle between the first bright star and the second bright star.

In use, a user initializes the telescope by turning on the telescope, pressing one of a plurality of buttons of the control unit, or simply supplying power. Upon initialization, the processor directs the drive mechanism to scan the sky until the vision device senses the first bright star. The first bright star is then substantially centered within the vision device's field of view and the motion signal is initialized.

It is important to note that, as used here, the first bright star does not relate to any specific star. The first bright star only implies that the first bright star is actually sensed first, upon initialization. As such, the first bright star may actually be a different star each time the telescope is initialized. Furthermore, the first bright star may actually be a planet or another celestial object that is brighter than surrounding space. The same principal applies to the second bright star and any other bright stars sensed by the telescope.

After initializing the motion signal, the processor directs the drive mechanism to scan the sky in search of the second bright star. Once the vision device has sensed the second bright star, the processor fine tunes the drive mechanism to substantially center the second bright star in the vision device's field of view. The processor then copies the measured angle from the motion signal. This process is preferably repeated until several measured angles provide a unique solution, from which the orientation of the telescope may be determined.

For example, the processor compares the measured angles with a matrix stored in the database to determine the orientation of the telescope. Specifically, when the processor matches the measured angles with a portion of the matrix, the bright stars associated with the measured angles have been identified. Once the bright stars are identified, the processor can use the location information of the bright stars to determine the orientation of the telescope. It is important to note that the user has not been required to provide any information to the telescope, such as location, orientation, or date.

Once the orientation is known, the processor may then find virtually any star or other celestial object specified by a user. For example, the user preferably identifies a specified star using buttons of the control unit. The processor searches the database to find location information for the specified star. The processor then instructs the drive mechanism to align the tube with the specified star. The processor may use the vision signal to fine tune the drive mechanism in order to substantially center the specified star within the tube's field of view.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT

Referring toFIG. 1, the preferred automatic telescope10constructed in accordance with a first embodiment of the present invention is illustrated as a stand-alone system capable of determining an orientation of the telescope10without requiring input from a user. Additionally, the telescope10may automatically align itself with virtually any star or other celestial object specified by the user. As such, the telescope10of the present invention preferably incorporates capabilities shown in “AUTO-ALIGNMENT TRACKING TELESCOPE MOUNT”, U.S. Pat. No. 6,369,942, hereby incorporated into the present application by reference. The telescope10broadly comprises an optical telescopic tube12for magnifying distant objects, a base14for supporting the tube12, a cradle16for securing the tube12to the base14, a drive mechanism18for moving the tube12with respect to the base14, and a control unit20to control the drive mechanism18.

The tube12is preferably conventional with manual focus and zoom functions. Alternatively, the tube12may incorporate automatic focus and/or automatic zoom functions controlled by the control unit20. Furthermore, the tube12may incorporate other electrical components, such as those discussed below and associated with the control unit20.

The base14is preferably a conventional tri-pod, but may be a base-plate designed to be mounted to a support surface. The cradle16may comprise a conventional yoke mounting assembly or another support assembly that allows the tube12to move with respect to the base14. The drive mechanism18preferably comprises a plurality of stepper motors to govern an altitude angle and an azimuth angle of the tube12with respect to the base14.

Referring toFIG. 2, the control unit20preferably includes a database22to store astronomical information and a processor24to align the tube12with a specified star using the drive mechanism18. The database22preferably includes information about stars and other celestial objects, such as nebulae. The information preferably comprises relational location information, such that each celestial object's location is described in relation to other celestial bodies. Alternatively, the location information may include an orbital path for each celestial object with respect to some reference point, such as the earth, the moon, or the sun. The information preferably also includes details relating to each celestial object, such as position, size, magnitude, type of object, and identification information for each object.

The control unit20also preferably includes a vision device30to electronically sense bright stars and a motion sensor32to sense motion of the tube12of the telescope10. The vision device30is preferably securely aligned with the tube12and may be secured to the tube12or the cradle16. In fact, the vision device30and the tube12preferably share substantially identical fields of view. However, while the vision device30must move with the tube12, the vision device30may be oriented at an angle to the tube12. For example, the vision device30may be oriented at up to ninety degrees with respect to the tube12. Such a modification may provide the vision sensor30with a less obstructed field of view.

In either case, the vision device30preferably comprises a charge-coupled device (CCD) camera, but may comprise some other optical sensor. The vision device26preferably generates a vision signal representative of an image in the vision device's field of view. Thus, when the tube12and the vision device30are aligned and pointed at a first bright star the vision signal is representative of the first bright star.

Similarly, the motion sensor32is preferably securely aligned with the tube12and may be secured to the tube12or the cradle16. The motion sensor32preferably comprises two motion encoders, one encoder to sense changes in an altitude angle and one encoder to sense changes in an azimuth angle of the tube12. The motion sensor32preferably generates a motion signal representative of changes in the altitude and azimuth angles. Therefore, when the tube12is slewed from alignment with the first bright star to a second bright star, the motion signal is preferably representative of a measured angle between the first and second bright stars comprising the altitude and azimuth angles between the first and second bright stars.

It is important to note that, as used here, the first bright star does not relate to any specific unique star. The first bright star only implies that the first bright star is actually sensed first, upon initialization. As such, the first bright star may actually be a different star each time the telescope10is initialized. In addition, the first bright star may actually be a planet or another object that is brighter than surrounding space. The same principal applies to other bright stars sensed by the telescope10.

The processor24uses measured angles, such as that described above, to calculate the orientation of the telescope10. To this end, referring toFIG. 3, the database22preferably contains a matrix of central angles between all known stars. For example, a first known star has a first central angle with respect to a second known star, a second central angle with respect to a third known star, and a third central angle with respect to a fourth known star. In addition, the second known star also has a fifth central angle with respect to the third known star, a sixth central angle with respect to the fourth known star, and so on. Specifically, for n bright stars, there are preferably (n2−n)/2 central angles stored in the matrix. Alternatively, the matrix may store vertex angles between the known stars. For efficiency, the angles stored in the matrix are preferably limited to those having a magnitude greater than two degrees.

It should be obvious that, since the goal of the present invention is to determine the orientation of the telescope10, the processor24is expected to determine which known star corresponds to the first bright star. Additionally, if the measured angle between the first and second bright stars exactly and uniquely matches one of the central angles in the database22, the processor24still must determine which bright star corresponds to which known star.

In order to accomplish this, the processor24preferably compares several measured angles with the central angles stored in the matrix of the database22. When the processor24finds sufficient matches between the measured angles and the central angles, with sufficient certainty as will be discussed in greater detail below, then the processor24has effectively identified the bright stars using the bright stars' relationship to one another. Once the bright stars are identified, the processor24can use the location information of the bright stars to determine the orientation of the telescope10.

For example, a set measured angles between several bright stars is compared to the central angles in the matrix. Any measured angles that nearly match the central angels result in a non-zero objective function score, which will be discussed in greater detail below, and are used to determine the orientation of the telescope10.

For amateur astronomy purposes, we can assume that the stars are fixed, with respect to each other and the earth. This assumption greatly simplifies the matrix, allowing the matrix to store fixed values for the central angles, as shown inFIG. 3. However, for more advanced purposes, the matrix may be date dependant. For example, the matrix may comprise relational functions using the date as a variable, thereby compensating for relative movement between the stars, the planets, and the earth. The telescope10may, include a real time clock, receive the date from the user, or determine the date from positions of the bright stars or planets.

The processor24automatically compensates for relative movement of objects used as bright stars, even if the matrix does not account for relative movement. For example, it can be assumed that there will be some degree of error between the measured angles and the central angles stored in the database22. Thus, as the processor24attempts to match the measured angles to the central angles, the processor24assigns an objective function score to each potential match. As discussed above, any measured angles that nearly match the central angles result in the non-zero objective function score. For instance, if the measured angle exactly matches one of the central angles, then the objective function score for that match is one. Alternatively, if the measured angle varies from a closest central angle by one or more degrees, then the objective function score for that match is zero and that match is effectively ignored. For matches with errors between zero and one degrees, the objective function score for those matches varies linearly between one and zero. In this manner, each central angle in the matrix is preferably compared with the each measured angle to determine the objective function score for each measured angle. Then, the objective function score may be determined for the set of measured angles. Accuracy may be further refined by multiplying the objective function score for each measured angle by the objective function score for the set of measured angles. Such refinement emphasizes close matches, while highlighting questionable matches.

Planets are often very bright, and therefore may be sensed as the bright stars. However, the planets typically have much more relative movement, with respect to the earth, than do most stars. Thus, when planets are used as bright stars, the matrix preferably compensates for this relative movement and is date dependent. Alternatively, the planets may simply be ignored when determining the location and orientation. For example, measured angles involving planets are not likely to sufficiently match any of the central angles in the matrix, if the matrix is not date dependent. Thus, measured angles involving planets are likely to vary by more than one degree from the central angles, resulting in the objective function score for any potential match being zero and those matches being ignored by the processor24. This is especially apparent when one realizes that the processor24is comparing the measured angles between several bright stars.

The control unit20also preferably includes a handheld remote control34that includes a display and a plurality of buttons allowing the user to interact with the telescope10. The remote control34preferably communicates with the control unit20over a wired connection, but may communicate over a wireless connection.

In use, the user initializes the telescope10by turning on the telescope10, pressing one of the buttons on the remote control34, or simply supplying power. Upon initialization, the processor24directs the drive mechanism18to scan they sky until the vision device30senses the first bright star.

The processor24preferably senses the first bright star by analyzing the vision signal. For example, the processor24analyzes the vision signal to find spots in the sky that are significantly brighter than other light emitting or reflecting bodies. These bright spots are assumed to be and used as bright stars. For example, the vision device30may provide a wide-angle view of the sky, from which the processor24may sense several bright stars. In this case, the processor selects one of the bright stars as the first bright star.

Alternatively, the drive mechanism18may scan the sky by varying the altitude angle, the azimuth angle, or both. For example, the drive mechanism18may use one of a plurality of predefined search methods, or a random search method, to sense the bright stars. One predefined search method comprises pivoting the tube12through 360 degrees of azimuth angle, incrementing the altitude angle slightly, and then repeating this process. The random search method preferably comprises changing the altitude azimuth angles substantially randomly until the first bright star is sensed.

In either case, once the vision device30has sensed the first bright star, the processor24fine tunes the drive mechanism18to substantially center the first bright star within the vision device's30field of view. Once the processor24centers the first bright star within the vision device's30field of view, the processor24initializes the motion signal. Then, the processor24directs the drive mechanism18to once again scan the sky in search of the second bright star. Once the vision device30has found the second bright star, the processor24fine tunes the drive mechanism18to substantially center the second bright star in the vision device's30field of view and temporarily stores the measured angle copied from the motion signal. This process is preferably repeated for several bright stars until the measured angles between the bright stars provide a unique solution, from which the orientation may be determined. While it may be possible to determine the unique solution with as few as two bright stars, it is anticipated that more bright stars and several measured angles will typically be required. In fact, the telescope preferably senses four bright stars and uses six measured angles between the four bright stars to determine the orientation of the telescope10.

Once the orientation of the telescope10is known, the processor24may then find virtually any star or other celestial object specified by the user. For example, the user preferably identifies the specified star using the remote control34, by selecting the specified star from a list or entering the specified star's name. The processor24searches the database22to find location information for the specified star. The processor24then instructs the drive mechanism18to align the tube12with the specified star. The processor24may use the vision signal to fine tune the drive mechanism18in order to substantially center the specified star within the tube's12field of view.

The flow charts ofFIGS. 4-5show the functionality and operation of a preferred implementation of the present invention in more detail. In this regard, some of the blocks of the flow charts may represent a module segment or portion of code of a program of the present invention which comprises one or more executable instructions for implementing the specified logical function or functions. In some alternative implementations, the functions noted in the various blocks may occur out of the order depicted. For example, two blocks shown in succession may in fact be executed substantially concurrently, or the blocks may sometimes be executed in the reverse order depending upon the functionality involved.

Referring toFIG. 4, the user initializes the telescope10, as depicted in step4a. The telescope10senses the first bright star and initializes the motion signal, as depicted in step4b. Then, the telescope10senses the second bright star and copies the measured angle from the motion signal, as depicted in step4c. Then, the telescope10senses another bright star and copies another measured angle from the motion signal, as depicted in step4d. When the processor24has at least two measured angles, the processor24compares the measured angles with the central angles in the matrix of the database22using the objective function score, as depicted in step4e. If the processor24does not find the unique solution, the telescope10repeats steps4d-e. If the processor24finds the unique solution, then the processor24has identified the bright stars and may determine the orientation of the telescope10using the information stored in the database22, as depicted in step4f.

Referring toFIG. 5, once the orientation of the telescope10is known, the user may enter the specified star using the remote control34, as depicted in step5a. The processor24retrieves location information for the specified star from the database22, as depicted in step5b. Then, the processor24instructs the drive mechanism18to align the tube12with the specified star, as depicted in step5c. The processor24may fine tune the drive mechanism18to substantially center the specified star within the tube's12field of view using the vision device30, as depicted in step5d. At this point, the user may view the specified star through the tube12.

In a second embodiment of the present invention, the telescope10is adapted to allow the user to manually align the tube12with bright stars or other celestial objects in addition to automatically scanning the sky for celestial objects. In the second embodiment, for example, the telescope10may include a switch that is part of the control unit20and is operable to selectively allow the telescope10to be slewed manually or via the drive mechanism18. This embodiment has the advantage of presenting a faster method of orienting the telescope, as the user will be able to quickly identify the locations of several celestial objects and successively align the tube12with each celestial object.

According to the second embodiment, the telescope10determines its orientation in a manner substantially similar to that of the first embodiment described above, except that the motion sensor32senses motion of the tube12caused by a user manually (i.e., by hand) rotating the tube12. A user may select a plurality of celestial objects, for example, and rotate the tube12to align with a first celestial object, then a second celestial object, then a third celestial object, etc. As the user rotates the telescope tube12, the motion sensor32generates a motion signal representative of a measured angle between each of the celestial objects.

While various embodiments of the present invention have been described above, it is understood that substitutions can be made. For example, depending on the quality of the vision device30, the tube12may not be required. In this case, the user may view the display or another screen which displays the image from the vision device30. The telescope10may not even require the tube12or the vision device30to actually move, in order to determine the orientation of the telescope10. For example, the vision device30may simply take a wide-angle snap-shot of the sky and sense several bright stars from the snap-shot. In this case, the measured angles may be inferred by spacing of bright stars in the snap-shot. Additionally, the drive mechanism18may use other types of motors and may include gears and other components commonly found in typical drive mechanisms. Furthermore, the database22may only include information about selected celestial bodies, such as constellations. These and other minor modifications are within the scope of the present invention.