Apparatuses and methods for applying forces to a structure utilizing oscillatory wing motions in a fluid

Methods and apparatuses are disclosed that rotate a first member about a first point relative to a chassis, wherein the first member is rotatably coupled to a second member at a second point. A second member is counter-rotated at a ratio of the rotational speed of the first member wherein the second member is rotatably coupled to the third member at a third point. The third point is translated in response to the counter-rotating second member in oscillatory motion along a path. The third member is pivoted at a third point and fluid is moved in response to the motion of the third member. A force is applied to the chassis due to the interaction of the third member and the fluid.

BACKGROUND OF THE INVENTION

1. Field of Invention

Embodiments of the invention relate generally to methods and apparatuses that develop forces on a wing and, more specifically, to methods and apparatuses for generating lift utilizing oscillatory wing motions.

2. Art Background

Both fixed wing and rotary wing aircraft, such as airplanes and helicopters, employ fluid flow over a foil such as a wing or rotor, thereby producing the lift necessary to enable flight. Such flow occurs over a cambered surface at a relatively low angle of attack.

Fixed wing aircraft are able to fly at high speeds but require a runway in order to attain sufficient speed to create enough lift to become airborne. This can be a problem when it is desirable to operate such an aircraft on a runway of limited length. Also, it is difficult to build a fixed wing aircraft that can hover. One example is a Harrier Jet. Such a vertical takeoff jet requires a large amount of fuel to hover. The hover time is limited and a large amount of water is required to keep the jet engine cool during that time. Additionally, the surface of the ground beneath the jet during takeoff must be able to withstand the heat of the jet exhaust when the aircraft is executing a vertical takeoff. All of these aspects either singly or in combination may present a problem.

Rotary wing aircraft, on the other hand, are able to become airborne without a runway, yet these aircraft are unable to attain the high speeds of fixed wing aircraft. This may present a problem.

Rotary wing aircraft utilize a foil at a relatively low angle of attack to the flow and as the name “rotary” implies, constrain the foil to rotate about a fixed axis. Additionally, a rotary wing aircraft employs a tail rotor to prevent counter rotation of the vehicle. Such constraints of angle of attack, rotation of the foil about a fixed axis, tail rotor, etc. place design constraints on resulting vehicle designs that use a rotary foil. This may present a problem.

DETAILED DESCRIPTION

In the following detailed description of embodiments, reference is made to the accompanying drawings in which is shown by way of illustration, specific embodiments in which the invention may be practiced. These embodiments are described in sufficient detail to enable those of skill in the art to practice the invention. In other instances, well-known structures and techniques have not been shown in detail in order not to obscure the understanding of this description. The following detailed description is, therefore, not to be taken in a limiting sense, and the scope of the invention is defined only by the appended claims.

In various embodiments, apparatuses and methods are disclosed to create forces between a fluid and a structure, such as a member, by utilizing motions that rotate and translate the member simultaneously during oscillatory motion. In various embodiments, oscillatory translational wing motions incorporate variable pitch angles of large amplitude and/or variable stroke plane angles.

FIG. 1Aillustrates one embodiment of a wing drive unit generally at100. With reference toFIG. 1A, a first member102is rotated about a first point104. For clarity of illustration, the first member102is rotatably coupled to a chassis (not shown) at the first point104. A second member106is rotatably coupled with the first member102at a second point108. A third member110is rotatably coupled to the second member106at a third point112. The third member110is pivotally supported by the chassis (not shown) at a fourth point116.

The first member102can be rotated either clockwise or counter-clockwise about the first point104. In one embodiment, the first member is rotated clockwise about the first point104as indicated by an arrow (about the first point104) at an arbitrary rate of n revolutions per unit time. The second member106is configured for rotation in a direction counter to the direction of rotation of the first member102. A rate of rotation of the second member106is related to a rate of rotation of the first member102. In one embodiment, the second member rotates in the counter-clockwise direction at a rate of 2n revolutions per unit time, as indicated by an arrow about the second point108.

The third point112travels in oscillatory motion along a trajectory indicated by a path114. The path114can be a linear path (as indicated inFIG. 1A) if a distance between the first point104and the second point108is equal to a distance between the second point108and the third point112. If these distances are not equal, then the path will follow a curve, which will have an amplitude above the path114during one-half cycle of the oscillatory motion and an amplitude below the path114during the other half cycle of the oscillatory motion, with end points of the curve falling on the path114.

The third member110is driven in oscillatory motion at the third point112. While in oscillatory motion, the third member110is configured to rotate about its longitudinal axis, thereby changing an angle of attack of a foil portion118relative to a fluid that the foil portion118moves through. The resulting motion of the foil in the immersed fluid creates a lift force that is imparted to the chassis. In the context of this description of embodiments, the foil portion118can also be referred to as a “wing portion.” The term “fluid,” is used generically to refer to a fluid such as water (fresh water or saltwater), oil, etc. or a gas such as air. For the remainder of this description, “pitch angle” will be used rather than “angle of attack” to describe the orientation of the wing. Pitch angle refers to the angle of the wing, as referenced from the chassis, and will be described further below. It will be noted that changing a pitch angle of the wing changes an angle of attack of the wing to the fluid.

FIG. 1Billustrates a process for flight, according to one embodiment, generally at150. In conjunction with the description provided above in relation toFIG. 1Aand with reference toFIG. 1B, rotary motion is converted into linear motion that is used to “drive” or “move” a foil or wing through a fluid. In block152a first member is rotated about a first point. In block154a second member is counter-rotated about a second point at twice the rotational speed of the first member which results in translating a third point in oscillatory motion at block156. A foil or wing member can be pivoted about a fourth point at block158to move the third member through a fluid at block160; thereby creating forces, such as lift forces, that are transferred to a chassis. The motion of the chassis through the fluid can be controlled by large amplitude motions of the foil or wing member relative to the chassis as well as large variations of pitch angle during the motion of the wing through its stroke plane.

FIG. 2illustrates one embodiment of a stroke plane generally at200. With reference toFIG. 2, a stroke plane is indicated at202. The stroke plane202defines a plane through which a wing member, such as the wing member118, oscillates within. A boundary206represents a first extreme position of the corresponding wing member at one end of a range of oscillatory motion while a boundary208represents a second extreme position of the corresponding wing member at a second end of the range of oscillatory motion. The boundary210represents a path taken by the wing tip during the oscillatory motion.

An orientation of the stroke plane202can be referred to by two angles: a stroke path angle and a wing dihedral angle. The stroke path angle is defined by a path that one end of the wing is driven within, such as the path114(FIG. 1A), relative to a chassis that the wing is attached to.

A wing dihedral angle is measured between the average orientation of a wing and a horizontal plane of the chassis. Referring back toFIG. 1A, movement of the point116along the Z axis changes a wing dihedral angle of the wing118relative to the chassis (not shown). For the purpose of referencing the wing dihedral angle in this example, the plane of the chassis can be considered to be parallel to the XY plane.

FIG. 3Aillustrates one embodiment of a wing drive unit in perspective view generally at300A.FIG. 3Billustrates a top down, partial cross-sectional view of the wing drive unit fromFIG. 3A, generally at300B.FIG. 3Cillustrates a cross-sectional view of the wing drive unit shown inFIG. 3B, generally at300C.FIG. 3Dshows a front view of a portion of the wing drive unit shown inFIG. 3A.

Referring toFIG. 3C, in one embodiment a first axle303is releasably coupled to a chassis at360. The first axle303is rotatably mounted in a first tube with bearings304. The first tube302is releasably coupled to the chassis at350. A first member300is rotatably coupled to the first tube302and the first axle303with bearings305. A gear301is attached to the first member300. In one embodiment, the gear301is a spur gear. In one embodiment, the gear301is used to rotate the first member300about an axis308of the first axle303and the first tube302.

Coupled to the first tube302is a gear306. In one embodiment, the gear306is a 30 degree bevel gear. The gear306meshes with a gear314. In one embodiment, the gear314is a 60 degree bevel gear. The gear314is attached to a tube311. The tube311is rotatably mounted within the first member300with bearings310and is configured to rotate about an axis309.

A gear324is attached to a second axle320. In one embodiment, the gear324is a spur gear. The second axle320is rotatably mounted in a second tube319with bearings321. The second axle320is rotatably mounted to rotate about an axis327and the second axle is coupled to a gear323. In one embodiment, the gear323is a 45 (forty-five) degree miter gear.

In one embodiment, the second tube is rotatably mounted in the first member300with a first bearing318and the second axle is rotatably mounted in the first member300with a second bearing318. The second tube319is coupled to a gear322and the second tube319is coupled to a second member325. In one embodiment, the gear322is a 45 (forty-five) degree miter gear.

It is understood, that the first member300, can be rotated in either a clockwise or counter-clockwise direction around the axis308. A rotational speed of the second member325is related to a rotational speed of the first member300. The description that follows is directed to counter-clockwise rotation of the first member300about the axis308.

The second member325is configured to rotate in a direction counter to the rotation of the first member300. In one embodiment, rotation of the first member300about the axis308in a counter-clockwise direction at a speed of n revolutions per unit time, as indicated by an arrow around the axis308, results in rotation of the tube311, in a clockwise direction, at a speed of 2n when the axis309is observed from an end that a gear315is attached. In one embodiment, the gear315is a 45 (forty-five) degree miter gear. The second axle counter-rotates (relative to the rotation of the first member300) in a clockwise direction about the axis327.

Referring back to the first axle303, a gear307is coupled thereto. In one embodiment, the gear307is a 45 (forty-five) degree miter gear. A third axle312is rotatably mounted within the tube311with bearings313. The third axle312is coupled to gears316and317. In one embodiment, the gears316and317are 45 (forty-five) degree miter gears. The gear307meshes with the gear316and the gear317meshes with the gear323.

Rotation of the first member300in the counter-clockwise direction causes the second axle320to counter-rotate in the clockwise direction as indicated by an arrow around the second axle320. Counter-rotation of the second axle320causes the gear324to maintain its rotational orientation relative to the chassis, since the gear324counter-rotates around the axis327at a rate of n revolutions per unit time. It will be noted that while the gear324rotates around the axis308at a rate of n, the counter-rotation of the gear324around the axis327at the same rate n (however different in direction) cancels out any effective change in angular orientation of the gear324relative to the chassis.

With reference toFIG. 3B, a gear334is rotatably mounted via a shaft332to the second member325and the gear334is configured to rotate around an axis340. In one embodiment, the gear334is circular. A gear335is coupled to the gear334. In various embodiments, the gear335is circular or non-circular (such as elliptical) and the gear335does not have to be mounted on its center. A gear330is selected to match the shape of the gear335. The gear330is rotatably coupled to the second member325to rotate around an axis333. In one or more embodiments, the gears335and330are unilobe elliptical gears that are mounted off axis with the same angular orientation (FIG. 3D). Such a configuration provides for a pitch angle that varies during the oscillatory motion of a third member337(FIG. 3AandFIG. 3B).

Referring now toFIG. 3A, the third member337is rotatably coupled via a universal joint336to the second member325at a third point that is coincident with the axis333of an axle329. The axle329is rotatably mounted in the second member325with a bearing331(FIG. 3D). The third point (coincident with the axis333) moves in oscillatory motion, following a path, as described above in conjunction withFIG. 1A. The path is linear when a distance between the axis308and the axis327is equal to a distance between the axis327and the axis333. If the distances are not equivalent, then the path will be curved as described above in conjunction withFIG. 1A.

In one embodiment, the third member337is pivotally supported by a pivot point338/339. In one embodiment,338is a bearing. In one embodiment, the bearing338is a linear-rotary bearing. In one embodiment,339is a coupling. In one embodiment, the coupling339is a universal lateral coupling. The third member337has a wing portion341. The orientation of the path, described immediately above, and a position of the pivot point338/339, relative to a chassis, define a stroke plane for the wing portion341. Referring back toFIG. 3C, an angle between the stroke plane and the chassis can be changed by rotating the first tube302relative to the chassis at350. Such a relative rotation between the first tube302and350(at a fixed angle between the first member300and the chassis) causes an angle formed between the first member300and the second member325to change, thereby changing the angle between the stroke plane and the chassis.

Adjustment of the median pitch angle or instantaneous pitch angle is accomplished by rotating the first axle303relative to the chassis at360. Rotation of the first axle303causes a corresponding rotation of the third member337(FIG. 3AandFIG. 3B), thereby the pitch angle of the third member337and wing portion341can be adjusted. It will be noted that in some embodiments a pitch angle of a third member and wing portion oscillate about a mean position utilizing gears that have been mounted off center and/or are non-circular, such as elliptical in shape.

With reference toFIG. 3D, it will be noted that the gear324and the gear330do not gain a net rotation with respect to the chassis. However, the rate of rotation of the gear330is not constant when the gear330is rotatably mounted on an axis that is not coincident with its geometrical center. In such a case, it will be noted that the gear335is likewise configured (mounted on an axis that is not coincident with its geometrical center). The gear330will rotate at a speed that slows down and speeds up in an oscillating fashion. When a distance between the axis333(FIG. 3B) of the gear330and the adjacent gear335is at a minimum, the rotation speed of the gear330is at a maximum. Conversely, when the distance between the axis333(FIG. 3B) of the gear330and the adjacent gear335is at a maximum, the rotation speed of the gear330is at a minimum. The resulting oscillation of the gear330produces an oscillating pitch angle of the wing portion341(FIG. 3A). Such an oscillation can be tailored by adjusting a distance that the gears330and335are mounted off of their geometrical centers.

In one embodiment, an example of a variable wing pitch angle is illustrated below inFIG. 11, where the wing pitch angle varies by approximately ±60 degrees. Embodiments of the present invention are not limited to the variation in wing pitch angle presented in this description. An unlimited number of different wing pitch angles can be achieved by application of the teaching presented herein. All such resulting wing pitch angles are within the scope of embodiments presented within this description of embodiments.

Referring back toFIG. 3AandFIG. 3D, in various embodiments, the first and second members can be supported by utilizing an inner circular member326and an outer circular member328. The inner circular member326is coupled to the second member325, such that the geometrical center of the inner circular member326is coincident with the axis327. The inner circular member326has a radius equal to a distance between the axis333and the axis327.

The outer circular member328has a geometrical center that is positioned to be coincident with the axis308. The outer circular member328is attached to the chassis and the inner and outer circular members are configured for aligned rolling contact. In one embodiment, the inner circular member326rolls inside of the outer circular member328being supported thereby.

FIG. 3Eillustrates one embodiment for connecting the wing drive unit ofFIG. 3Ato a chassis, generally at300E. With reference toFIG. 3E, a rotating element343delivers power to the wing drive unit by means of rotation. In one embodiment, the rotating element343is a drive shaft. In another embodiment, the rotating element343is a flexible shaft configured in a housing. A bearing346provides for rotatable support of the rotating element343through a chassis344. The rotating element343is coupled with a drive gear342. In one embodiment, the drive gear342is a spur gear. The drive gear342meshes with and rotates the gear301which in turn causes the first member300(FIG. 3BandFIG. 3C) to rotate around the first axle303and the first tube302. The first axle303is supported by a bearing345and the chassis344. As previously described in conjunction withFIG. 3A,FIG. 3B,FIG. 3C, andFIG. 3D, the universal joint336, which is coincident with the axis333, travels in an oscillating path due to the application of power by means of rotating element343. Thereby, the wing portion341is made to move through large amplitude motions, both along the stroke plane and rotation due to a variable pitch angle while in motion along the stroke plane.

FIG. 4shows, in cross section, one embodiment of circular members, generally at400. With reference toFIG. 4, an inner circular member426is configured for rolling contact with an outer circular member428. It will be noted that many configurations of such circular member cross-sectional shapes are possible and the illustration ofFIG. 4is but one example. Accordingly, all such other examples are within the scope of embodiments contemplated by this description.

FIG. 5illustrates one embodiment of a pivot point, generally at500. With reference toFIG. 5, a member537is pivotally supported by a linear-rotary bearing538and a universal lateral coupling539. Such a configuration permits rotation of the member537as well as repositioning of the member537, for example, during oscillatory motion along a path as previously described above in conjunction with the preceding figures. Embodiments of the present invention are not limited by the way in which a member is pivotally supported. The example ofFIG. 5is but one example and other mechanisms can be used for pivotal support. For example, in another embodiment a pivotal support can include a gimbals and the member537can be telescopic.

FIG. 6illustrates one embodiment of a chassis, generally at600A. With reference toFIG. 6, a chassis344is configured with four wing drive units. A source of power602is centrally located on the chassis344and provides power to each wing drive unit through separate rotating elements, such as the rotating element343providing power to the drive gear342.

In other embodiments, individual wing drive units can be powered from independent sources of power. In yet other embodiments, a group of wing drive units can be powered from an individual source of power. In yet other embodiments, multiple sources of power can be configured to power one or more wing drive units, thereby providing power redundancy.

FIG. 7illustrates one embodiment of incorporating circular members into a chassis generally at600B. With reference toFIG. 7, a source of power is centrally located at602. The source of power602provides power to the four wing drive units, as shown inFIG. 6. Circular members provide support for the wing drive units and are configured into the chassis as shown in one embodiment. Alternatively, in other embodiments, individual sources of power can be supplied to the wing drive units or to a group of wing drive units.

FIG. 8Aillustrates a position of wing shaft pivot points configured for hovering, according to one embodiment generally at800A. With reference toFIG. 8A, four pivot points,804a,804b,804c, and804dare configured into a substantially uniform circumferential distribution about a chassis802. A member806apivots about the pivot point804a, the pivot point804ais in a first location. A member806bpivots about the pivot point804b, the pivot point804bis in a first location. A member806cpivots about the pivot point804c, the pivot point804cis in a first location. A member806dpivots about the pivot point804d, the pivot point804dis in a first location.

FIG. 8Billustrates a position of wing shaft pivot points configured for translational motion, according to one embodiment, generally at800B. With reference toFIG. 8B, the pivot point804ahas moved to a second location as indicated by an arrow810. The pivot point804bhas moved to a second location as indicated by an arrow812. Members806aand806bform a wing pair on a first side of the chassis802.

The pivot point804chas moved to a second location as indicated by an arrow814. The pivot point804dhas moved to a second location as indicated by an arrow816. Members806cand806dform a wing pair on a second side of the chassis802.

In various embodiments, translational motion along a direction indicated by an arrow820occurs with the pivot points804a,804b,804c, and804dconfigured as shown. It will be noted that other locations of the pivot points are possible for translational motion. No limitation is implied by the location of the pivot points804a,804b,804c, and804das illustrated inFIG. 8Baccording to one example.

FIG. 9Adepicts adjustable pivot points, according to one embodiment, generally at900. With reference toFIG. 9A, four wing members,908a,908b,908c, and908dare shown connected to a chassis910. The wing members are configured to be driven in oscillatory motion, as described above in conjunction with the preceding figures. An adjustable pivot point904ais configured to permit a member906ato be repositioned relative to a second pivot point904band its corresponding member906b. Such repositioning of the pivot points904aand/or904bcan be accomplished in a variety of ways, as is known to those of skill in the art, such as, but not limited to, by utilizing a movable track, a movable panel with a slot, etc.

In various embodiments, movement of a pivot point in two dimensions is also readily accomplished. In one embodiment, such movement is accomplished by combining multiple movable layers, such as two movable panels922and932as illustrated inFIG. 9B. With reference toFIG. 9B, in an exploded view920, a first panel922has a slot924and a second panel932is configured with a slot934oriented at an angle, such as 90 (ninety) degrees relative to the first slot924. The panels are arrayed in a layered fashion, one in front of the other, and a member960protrudes through each slot approximately in perpendicular orientation to the two parallel panels as shown in a view940. A point962at which the member960protrudes through the panels922and932represents the movable pivot point.

Motion in a first dimension, indicated by an arrow926, occurs when the first panel922is moved relative to the second panel932, which causes the member960to be moved through the slot934in the second panel932in the first dimension (or direction)926. Motion in a second dimension, indicated by an arrow936, occurs when the second panel932is moved relative to the first panel922, which causes the member960to be moved through the slot924in the first panel922in the second dimension (or direction)936. The arrangement of slots shown permits the point962to be moved anywhere with the area of a circle indicated by950. Variations are readily implemented that allow motion within a plane or surface by simultaneous movement of both panels.

Moving a pivot point as described above can be used to adjust a dihedral angle of a wing. Accordingly, a dihedral angle of a wing member can be adjusted independently of the dihedral angles of the other wing members or the dihedral angles of the wing members can be adjusted in unison.

FIG. 10illustrates an array of wing members, according to one embodiment, generally at1000. With reference toFIG. 10, a chassis1002has a plurality of wing drive units attached thereto. The plurality of wing drive units1004,1006,1008, and1010is a group of four in the example shown inFIG. 10. However, any number of wing drive units can be combined in horizontal rows or vertical stacks. Wing drive units can be grouped into pairs, as described above in conjunction withFIG. 8B. Any combination of wing drive units is possible within the teaching of embodiments presented herein and no limitation is implied by the examples given. The arrangements shown in the figures are only examples of the many different configurations that are possible and those of skill in the art will recognize that many other configurations (not shown) are possible.

FIG. 11illustrates a functional relationship between pitch angle of a wing member and rotation of a second member with reference to the chassis, according to one embodiment generally at1100. With reference toFIG. 11, in various embodiments, a vertical axis1102displays a pitch angle of a member or a wing portion, such as but not limited to118(FIG. 1A),341(FIG. 3A), etc. A horizontal axis1104displays rotation of a second member about a second point, such as, but not limited to,106(FIG. 1A),325(FIG. 3B), etc. A variation of pitch angle with rotation of a second member (a functional relationship) is displayed at1106.

The functional relationship1106is one of the many functional relationships that can be created by varying the shape and offset of rotation axes of the gears335and330(FIG. 3D). Referring back toFIG. 3D, for example, if the gears335and330are circular and are mounted for rotation on their geometrical centers, then the functional relationship1106(FIG. 11) would be a flat line. As an offset between the axis of rotation and the geometrical centers of the gears335and330increases, the amplitude of the oscillation in1106increases. It will be noted that gears335and330can be circular in shape mounted off of their geometrical centers as well as non-circular in shape. One type of non-circularly shaped gear is elliptical. In various embodiments, non-circular gears can be used for the gears335and330, consistent with a condition of contact between the gears during rotation about the axes that they are mounted on. It will be noted that the gears335and330are mounted with their respective principal axis in a parallel configuration as shown inFIG. 3D. While the pitch angle is shown to fluctuate approximately within the range of ±60 degrees in the functional relationship1106, embodiments of the present invention are not so limited. For example, a pitch angle can fluctuate within many other ranges depending on the parameters of a particular design, such as but not limited to, ±30 degrees or less, ±45 degrees, ±70 degrees, etc.

In some embodiments, it may be convenient to use an actuator to provide rotation of a wing member in order to change pitch angle. In various embodiments, an actuator can be built into or outside of an envelope of a member such as the third member110(FIG. 1A) or the third member337(FIG. 3A). The actuator can provide for rotation relative to a second member, such as106(FIG. 1A) or the second member325(FIG. 3A).

FIG. 12illustrates a variable pitch angle of a wing member, according to another embodiment. With reference toFIG. 12, a variation of pitch angle of a wing member1204is shown for nine positions (1200A,1200B,1200C,1200D,1200E,1200F,1200G,1200H, and1200I) of the wing member1204during one cycle of oscillatory motion. In one embodiment, the variation of pitch angle shown in theFIG. 12can be used for stationary flight, such as hovering.

In the nine positions shown inFIG. 12, a path1208of an end1202of a member (not shown) indicates an orientation of a stroke plane of the wing member1204. A reference line1210is arbitrarily shown in perpendicular orientation to the stroke plane1208and in arbitrary orientation to the wing member1204in all of the positions1200A,1200B,1200C,1200D,1200E,1200F,1200G,1200H, and1200I; however,1210and1208are only labeled in position1200A for clarity of illustration. It will be noted that a wing member need not rotate about an end point, but may be configured for rotation about a point along the length of the profile of the wing member. InFIG. 12,1204represents a profile of a wing member; however1204is referred to as “a wing member” to simplify the discussion of the figure. The reference line1210has been arbitrarily placed relative to the wing member1204and should not be used to limit interpretation of the figures.

In position1200A, the wing member1204is substantially at a first extreme position of its stroke (furthest right). The wing member1204makes an angle1206awith the reference1210. As the wing member1204moves to the left, as shown in position1200B, the wing member1204rotates counter-clockwise to a position as indicated by an angle1206b. In position1200C, the wing member1204continues moving to the left, at an angle indicated at1206c. In position1200D, the wing member1204continues moving to the left, at an angle indicated at1206d.

In position1200E the wing member1204is at a second extreme position of its stroke (furthest left). The wing member1204makes an angle1206ewith the reference1210in position1200E and the wing member1204rotates quickly in a clockwise direction as the wing member begins the second half of its oscillatory cycle. In position1200F, the wing member1204is traveling to the right and the wing member1204makes an angle as indicated at1206fwith the reference. In position1200G the wing member1204continues traveling to the right and the wing member1204makes an angle as indicated at1206gwith the reference. In position1200H the wing member1204continues traveling to the right and the wing member1204makes an angle as indicated at1206hwith the reference. Position1200I is substantially the same position as position1200A, which places the wing member1204back to the first extreme position of its stroke and the oscillatory motion begins a second cycle.

During the oscillatory motion as described above in conjunction withFIG. 12, the wing member1204moves in oscillatory motion at large pitch angles (approximately ±50 (fifty) degrees). Variation of the pitch angle during the oscillatory motion permits the wing member1204to maintain a positive angle of attack with respect to the flow in both halves of the oscillatory motion cycle. The fluid flow relative to the trajectory of the wing member1204departs from the classical steady state aerodynamic case. The trajectory of the wing member1204interacts with the fluid to form circulation due to rotation of the wing member about its axis during the variation of pitch angle. Additionally, as the wing member1204translates from right to left or from left to right, vortices shed from the edges of the wing member1204. A first vortex sheds from a first edge (top edge) rotating in a first direction and a second vortex sheds from a second edge (bottom edge) counter-rotating in a second direction. The pair of counter-rotating vortices produces a flow of fluid in the direction of the moving wing member1204. For example, the flow of fluid will be to the left in position1200D/1200E. As the wing member1204reverses direction and travels to the right in positions1200F/1200G, the wing member1204interacts with the flow of fluid produced by the pair of counter-rotating vortices; thereby, the wing member experiences enhanced lift acting on the wing member and the chassis, with which the wing member is connected. A similar interaction occurs when the wing member is traveling in the opposite direction during the other half cycle of its oscillatory motion.

FIG. 13Aillustrates wing tip trajectories during hovering, according to one embodiment, generally at1300. With reference toFIG. 13A, the previously described motions of the wing member1204(FIG. 12) are applicable to the four wing configuration illustrated inFIG. 13A. A first wing member1302is configured to oscillate in a stroke plane that has an outer boundary indicated by a wing tip path1304. A second wing member1306oscillates in a stroke plane that has an outer boundary indicated by a wing tip path1308. A third wing member1310oscillates in a stroke plane that has an outer boundary indicated by a wing tip path1312. A fourth wing member1314oscillates in a stroke plane that has an outer boundary indicated by a wing tip path1316. The motion and pitch angle of adjacent wing members is substantially 180 (one hundred eighty) degrees out of phase. In various embodiments, the wing members1302,1306,1310, and1314can be powered from one power source or the wing members can be individually powered or a group of wing members can be powered from a common power source.

FIG. 13Billustrates hovering, according to one embodiment, generally at1350. A chassis1370has four wing members:1352,1354,1356, and1358attached thereto and configured for oscillatory motion where a pitch angle and motion of adjacent wing members are substantially one hundred and eighty degrees out of phase. It will be noted by those of skill in the art that variations in pitch angle and/or stroke plane angle can be necessary to maintain a stable hovering relationship between the chassis1370and a ground reference plane1360. In one or more embodiments, variations in pitch angle of any one or more of wing members1352,1354,1356, or1358can be accomplished by instantaneous adjustment of the first axle303(FIG. 3C) relative to the chassis360(FIG. 3C). In one or more embodiments, variations in a stroke plane of any one or more of wing members1352,1354,1356, or1358can be accomplished by instantaneous adjustment of the first tube302(FIG. 3C) relative to the chassis350(FIG. 3C).

FIG. 13Cillustrates a process for flight according to another embodiment. With reference toFIG. 13C, at block1382a plurality of wing members is provided on a chassis. In various embodiments, the wing members can be arranged in wing pairs (or groups) or simply distributed on the chassis. At block1384each wing member is moved in oscillatory motion within a stroke plane. At block1386a pitch angle of a wing member is varied. At block1388fluid is moved relative to the chassis by the wing members. At block1390the pitch angle of adjacent wing members is substantially 180 (one hundred eighty) degrees out of phase.

It will be noted that there can be any number of wing members attached to a chassis. The pitch angles and/or stoke planes of each wing member can be varied to provide for the desired flight characteristic of the chassis. For example, currents in the fluid that the chassis/wing members are immersed in may require instantaneous variation of one or more wing member parameters (pitch angle, stroke plane) to compensate for drift relative to a ground reference plane, such as the ground reference plane1360(FIG. 13B).

FIG. 14illustrates a variable pitch angle of a wing member with an inclined stroke plane, according to another embodiment. With reference toFIG. 14, a variation of pitch angle of a wing member1404is shown for nine positions (1400A,1400B,1400C,1400D,1400E,1400F,1400G,1400H, and1400I) of the wing member1404during one cycle of oscillatory motion. In one embodiment, the variation of pitch angle shown in theFIG. 14can be used for translational motion of a chassis and associated wing members.

In the nine positions shown inFIG. 14, a path1408of an end1402of a member (not shown) indicates an orientation of a stroke plane of the wing member1404. A reference line1410is arbitrarily shown in perpendicular orientation to the stroke plane1408and in arbitrary orientation to the wing member1404in all of the positions1400A,1400B,1400C,1400D,1400E,1400F,1400G,1400H, and1400I; however,1410and1408are only labeled in position1400A for clarity of illustration. It will be noted that a wing member need not rotate about an end point, but may be configured for rotation about a point along the length of the profile of the wing member (1404represents a profile of a wing member; however1404is referred to as “a wing member” to simplify the discussion of the figure). The reference line1410has been arbitrarily placed relative to the wing member1404and should not be used to limit interpretation of the figures.

In position1400A, the wing member1404has passed through a first extreme position of its stroke (furthest right) and is moving in an upper left direction. The wing member1404makes an angle1406awith the reference1410in position1400A. In position1400B, the wing member1404continues moving to the left, at an angle indicated at1406b. As the wing member1404moves to the left, as shown in position1400C, the wing member1404rotates clockwise to a position as indicated by an angle1406c. In position1400D, the wing member1404is substantially at an extreme position of its stroke (farthest left position), at an angle indicated at1406d.

In position1400E, the wing member1404moves to the right, at an angle indicated at1406e. The wing member1404makes an angle1406ewith the reference in position1400E and the wing member1404rotates quickly in a clockwise direction as the wing member begins the second half of its oscillatory cycle. In position1400F, the wing member1404is traveling to the right and the wing member1404makes an angle as indicated at1406fwith the reference. In position1400G the wing member1404continues traveling to the right and the wing member1404makes an angle as indicated at1406gwith the reference. In position1400H the wing member1404is at a second extreme position of its stroke (furthest right position). Position1400I is substantially the same position as position1400A which starts the wing member1404traveling back in the left direction and the oscillatory motion begins a second cycle.

During the oscillatory motion as described above in conjunction withFIG. 14, the wing member1404moves in oscillatory motion at large pitch angles (approximately 60 degrees). Variation of the pitch angle during the oscillatory motion permits the wing member1404to maintain a positive angle of attack with respect to the flow in both cycles of the oscillatory motion.

FIG. 15Adepicts wing tip trajectories during forward flight, according to one embodiment, generally at1500A. With reference toFIG. 15A, the previously described motions of the wing member1404(FIG. 14) are applicable to the four wing configuration illustrated inFIG. 15A. A first wing member1502is configured to oscillate in a stroke plane that has an outer boundary indicated by a wing tip path1504. A second wing member1506oscillates in a stroke plane that has an outer boundary indicated by a wing tip path1508. A third wing member1510oscillates in a stroke plane that has an outer boundary indicated by a wing tip path1512. A fourth wing member1514oscillates in a stroke plane that has an outer boundary indicated by a wing tip path1516.

The wing member1502and the wing member1506form a first wing pair or group and the wing member1510and the wing member1514form a second wing pair or group. Motion between the wing member1502and the wing member1506is out of phase. In one embodiment, the motion of the wing member1506leads the motion of the wing member1502by a phase angle. In various flight configurations, the phase angle ranges up to 180 (one hundred eighty) degrees. Similarly, motion between the wing member1510and the wing member1514is out of phase. In one embodiment, the motion of the wing member1510leads the motion of the wing member1514by a phase angle. In various flight configurations, the phase angle ranges up to 180 (one hundred eighty) degrees.

For flight in a substantially straight line as indicated by an arrow1520, the motion of the wing pairs should be substantially mirrored. For example, the motion of wing member1506and1510is substantially in phase and the motion of wing member1502and the wing member1514is substantially in phase.

It will be understood by those of skill in the art, that as used in this description of embodiments, terms such as, “mirrored,” “substantially in phase,” “in phase,” “out of phase,” etc. are used to describe relative differences between a motion of a wing member in a first wing group (synonymous with wing pair) and a motion of a wing member in a second wing group (where the first wing group and the second wing group point in substantially opposite directions relative to a chassis on which they are attached). In the example ofFIG. 15A, the motion of a chassis1530is represented by the arrow1520. The arrow1520is parallel to an axis1542(X axis) of a local coordinate system centered on the chassis1530. The local coordinate system includes the X axis at1542, a Y axis at1544, and a Z axis at1546. When the motion of two opposing wing members, such as the wing member1506and the wing member1510is viewed, as in the example ofFIG. 15A, in the YZ plane of the local coordinate system, their motion is mirrored about the Z axis1546. When the motion of two opposing wing members, such as the wing member1506and the wing member1510is viewed, as in the example ofFIG. 15A, in the XZ plane of the local coordinate system, the motion is said to be “substantially in phase,” or “in phase.” Thus, the motion of wing members1506and1510can be equivalently described as mirrored (with reference to the YZ plane of the local coordinate system) or with reference to the XZ plane of the local coordinate system, “substantially in phase,” “in phase,” etc.

In the case of wing members within a wing group, located on a particular side of a chassis, such as in the example ofFIG. 15A, either a first wing group, which includes wing members1502and1506or a second wing group, which includes wing members1514and1510, terms using the word “phase” such as, “substantially in phase, “in phase,” “out of phase,” etc. are used at times to describe the motion between wing members within the wing group. As described above, during the forward flight in the example ofFIG. 15A, the motion of wing member1510is out of phase with motion of wing member1514and the motion of wing member1506is out of phase with the motion of wing member1502.

Therefore, those of skill in the art will understand that terms such as “mirrored,” “substantially in phase,” “in phase,” “out of phase,” etc. can be used to describe motions of different wing members or wing groups as referred to an appropriate reference plane of a local coordinate system associated with a vehicle during various forms of flight. In the example ofFIG. 15Athe vehicle is represented by the chassis1530and the wing members1502,1506,1510, and1514. In the figures that follow, such descriptive terms, “mirrored,” substantially in phase,” “in phase,” “out of phase,” etc. describe motions of different wing members, wing groups, etc. without explicitly illustrating a local coordinate system associated with a vehicle. It will be understood, however, that an appropriate local coordinate system is implied by the use of such terms as described above.

A wing pair or “group” can include more than two wing members; for example, a wing group can include a plurality of wing members. In such a configuration, the wing members within a wing group will have a phase angle between adjacent members. In an example with three wing members per group, a constant phase angle of α “alpha” degrees can exist between adjacent wing members within a wing group. In one example, α “alpha” equals 45 (forty-five) degrees. A 45 (forty-five) degree phase angle between wing members will place the motion of the second wing member 45 (forty-five) degrees behind the motion of the forward or first wing member. The motion of the third or last wing member will lag the motion of the first wing member by 90 (ninety) degrees and the third or last wing member will lag the motion of the second wing member by 45 (forty-five) degrees.

In other examples, a non-constant phase angle offset exists between the motion of wing members. In the case of three wing members per wing group, the second wing member's motion can lag the first wing member's motion by an angle of ψ “psi” degrees and the third wing member's motion can lag the second wing member's motion by an angle of θ “theta” degrees, where ψ “psi” does not equal θ “theta.”

FIG. 15Billustrates forward flight according to another embodiment, generally at1500B. A chassis1570has four wing members:1552,1556,1558, and1560attached thereto and configured for oscillatory motion in two wing groups as described above in is conjunction withFIG. 15A, wherein the wing member1552and the wing member1556form a first wing group and the wing member1558and the wing member1560form a second wing group with a phase angle existing between the motion of the wing members within a wing group. The motion of the wing groups is substantially mirrored.

FIG. 15Cillustrates translation in the positive Y direction, according to one embodiment, generally at1500C. With reference toFIG. 15C, the positions indicated by the wing members1552,1556,1558, and1560illustrate another snapshot of the continuous motion exhibited by the wing members as the chassis1570translates along the positive Y direction at1566.

FIG. 15Dillustrates translation in the negative X direction, according to one embodiment, generally at1500D. With reference toFIG. 15D, the positions indicated by the wing members1552,1556,1558, and1560illustrate another snapshot of the continuous motion exhibited by the wing members as the chassis1570translates along the negative X direction at1568.

In one embodiment, the views provided atFIG. 15B,FIG. 15C, andFIG. 15Dcan represent a one hundred and eighty degree turn that the chassis1570executes from translation in the positive X direction at1564(FIG. 15B) to translation in the negative X directionFIG. 15Dat1568. Such a turn (clockwise around the Z axis) can be accomplished by increasing the forward force imparted to the chassis by the wing members1552and1556relative to the forward force imparted to the chassis by the wing members1560and1558in a variety of ways. A first way increases the flap rate of the wing members1552and1556relative to the wing members1558and1560. A second way increases the relative pitch angle of the wing members1552and1556relative to the wing members1558and1560. A third way alters the wing members1558and1560to move in more of a hover motion relative to the motion of the wing members1552and1556.

It will be noted by those of skill in the art that variations in pitch angle and/or stroke plane angle might be necessary to maintain a stable flight path between the chassis1570and a ground reference plane1562. In one or more embodiments, variations in pitch angle of any one or more of wing members1552,1556,1558, or1560can be accomplished by instantaneous adjustment of the first axle303(FIG. 3C) relative to the chassis360(FIG. 3C). In one or more embodiments, variations in a stroke plane of any one or more of wing members1552,1556,1558, or1560can be accomplished by instantaneous adjustment of the first tube302(FIG. 3C) relative to the chassis350(FIG. 3C).

In one embodiment, the wing members,1552,1556,1558, and1560oscillate in stroke planes that are configured at one angle relative to a horizontal plane of the chassis1570. In some embodiments the angel is positive and in other embodiments the angel is negative.

FIG. 15Eillustrates a process for flight according to yet another embodiment. With reference toFIG. 15E, at block1582a plurality of wing members is provided on a chassis. In various embodiments, the wing members can be arranged in wing pairs or groups or simply distributed on the chassis. At block1584, each wing member is moved in oscillatory motion within a stroke plane. At block1586, a pitch angle of a wing member is varied. At block1588fluid is moved relative to the chassis by the wing members. At block1590the motion of a wing member on a first side of a chassis is substantially in phase with the motion of a corresponding wing member on a second side of a chassis.

In various embodiments, the process ofFIG. 15Eproduces translational flight with the stroke planes of wing members configured at an angle relative to a horizontal plane of a chassis. In some embodiments, the angle is positive and in some embodiments the angle is negative.

It will be noted that there can be any number of wing members attached to a chassis. The pitch angles and/or stoke planes of each wing member can be varied to provide the desired flight characteristics of the chassis. For example, currents in the fluid that the chassis/wing members are immersed in may require instantaneous variation of one or more wing member parameters (pitch angle, stroke plane) to compensate for drift relative to a ground reference plane, such as the ground reference plane1562(FIG. 15B-D).

FIG. 16shows rotation about the Z axis, according to one embodiment, generally at1600. With reference toFIG. 16, a chassis1670has four wing members attached thereto: a wing member1602, a wing member1604, a wing member1606, and a wing member1608. In one embodiment, the wing member1602and the wing member1604form a first wing group. The motion of the wing members1602and1604is substantially in phase. The wing member1606and the wing member1608form a second wing group. The motion of the wing members1606and1608is substantially in phase. The stroke planes of all the wing members,1602,1604,1606, and1608can be parallel to the Z axis. The motion between the two wing groups is substantially out of phase by one-half cycle; thereby equal and opposite forces are applied to the chassis1670resulting in a rotation1612about the Z axis.

FIG. 17Ashows rotation about the Z axis, according to one embodiment. With reference toFIG. 17A, a chassis1770has four wing members attached thereto: a wing member1702, a wing member1704, a wing member1706, and a wing member1708. In one embodiment, the wing member1702and the wing member1704form a first wing group. The motion of the wing members1702and1704is out of phase by a first phase angle. The wing member1706and the wing member1708form a second wing group. The motion of the wing members1706and1708is out of phase by the first phase angle. The stroke planes of the wing members1702and1704are at a first stroke plane angle and the stroke planes of wing members1706and1708are at the negative first stroke plane angle. The motion between the two wing groups is substantially out of phase by one-quarter cycle; thereby, equal and opposite forces are applied to the chassis1770resulting in a rotation1712about the Z axis.

FIG. 17Billustrates a process for flight according to yet another embodiment. With reference toFIG. 17B, at block1752a plurality of wing members is provided on a chassis. In various embodiments, the wing members can be arranged in wing pairs or groups or simply distributed on the chassis. At block1754, each wing member is moved in oscillatory motion within a stroke plane. At block1756, a pitch angle of a wing member is varied. At block1758, fluid is moved relative to the chassis by the wing members. At block1760, the motion of a wing member on a first side of a chassis is substantially out of phase by 180 (one hundred eighty) degrees with the motion of a corresponding wing member on a second side of a chassis. In various embodiments, the process ofFIG. 17Bis used for turning while in flight.

It will be noted that there can be any number of wing members attached to a chassis. The pitch angles and/or stoke planes of each wing member can be varied to provide for the desired flight characteristic of the chassis. For example, currents in the fluid that the chassis/wing members are immersed in may require instantaneous variation of one or more wing member parameters (pitch angle, stroke plane) to compensate for drift relative to a ground reference plane, such as the ground reference plane1610(FIG. 16) or1710(FIG. 17).

FIG. 18Aillustrates forward flight according to another embodiment, generally at1800A. A chassis1870has four wing members:1802,1804,1806, and1808attached thereto and configured for oscillatory motion in two wing groups. The wing member1802and the wing member1804form a first wing group and the wing member1806and the wing member1808form a second wing group. The motion of the wing members within a wing group is substantially in phase and the motion of the wing groups is substantially mirrored about the Z axis when viewed in the YZ plane. The wing members1802,1804,1806, and1808oscillate in stroke planes that are configured at an angle between 0 (zero) and 90 (ninety) degrees relative to a horizontal plane of the chassis1870. In one embodiment, the stroke planes are configured at a 45 (forty-five) degree angle relative to a horizontal plane of the chassis1870.

FIG. 18Billustrates translation in the positive Y direction, according to another embodiment, generally at1800B. With reference toFIG. 18B, the positions indicated by the wing members1802,1804,1806, and1808illustrate another snapshot of the continuous motion exhibited by the wing members as the chassis1870translates along the positive Y direction at1814.

FIG. 18Cillustrates translation in the negative X direction, according to another embodiment, generally at1800C. With reference toFIG. 18C, the positions indicated by the wing members1802,1804,1806, and1808illustrate another snapshot of the continuous motion exhibited by the wing members as the chassis1870translates along the negative X direction at1816.

In one embodiment, the views provided atFIG. 18A,FIG. 18B, andFIG. 18Ccan represent a single turn or a series of turns resulting in a 180 (one hundred and eighty) degree change in direction of the chassis1870without rotating the chassis1870about the Z axis1818. Such a turn can be accomplished by changing the stroke plane angles and pitch angles of the wing members1802,1804,1806, and1808while in flight. In one embodiment, the chassis transitions from translational motion to a hover. In one embodiment, such a transition can be accomplished by adjusting the pivot positions of the wing members, as described above in conjunction with the previous figures, wherein the wing groups are ungrouped to form uniformly spaced wing members during a hover and then the wing members are “regrouped” to provide translation of the chassis1870in the positive Y direction1814without rotation, as seen by comparing the wing member grouping inFIG. 18Aas compared with the wing member grouping inFIG. 18B. A similar regrouping of the wing members is observed by comparing the wing member grouping inFIG. 18Bas compared with the wing member grouping inFIG. 18C.

InFIG. 18Awing members1802and1804form one group and wing members1806and1808form another group. Wing members are regrouped inFIG. 18Bwhen wing members1806and1802form one wing group and wing members1808and1804form another wing group. As described above, the regrouping of wing members enables the chassis to change a direction of translation from the positive X direction1812to the positive Y direction1814without rotation about the Z axis1818.

It will be noted that another regrouping of wing members occurs betweenFIG. 18BandFIG. 18C, which enables the chassis to change a direction of translation from the positive Y direction1814to the negative X direction1816without rotation about the Z axis1818.

In yet another embodiment, a flight maneuver changes a direction from translation in a first direction (FIG. 18A) to a second direction (FIG. 18C) by changing the stroke plane angles of the wing members1802,1804,1806, and1808with or without an accompanying change in pitch angles of the wing members1802,1804,1806, and1808.

It will be noted by those of skill in the art that variations in pitch angle and/or stroke plane angle might be necessary to maintain a stable flight path between the chassis1870and a ground reference plane1810. In one or more embodiments, variations in pitch angle of any one or more of wing members1802,1804,1806or1808can be accomplished by instantaneous adjustment of the first axle303(FIG. 3C) relative to the chassis360(FIG. 3C). In one or more embodiments, variations in a stroke plane of any one or more of wing members1802,1804,1806or1808can be accomplished by instantaneous adjustment of the first tube302(FIG. 3C) relative to the chassis350(FIG. 3C).

It will be noted that there can be any number of wing members attached to a chassis. The pitch angles and/or stoke planes of each wing member can be varied to provide the desired flight characteristics of the chassis. For example, currents in the fluid that the chassis/wing members are immersed in may require instantaneous variation of one or more wing member parameters (pitch angle, stroke plane) to compensate for drift relative to a ground reference plane, such as the ground reference plane1810(FIG. 18A-C).

Various other maneuvers can be accomplished by adjusting wing member parameters such as the stroke plane angle or the pitch angle of the wing members. For example, pitching a front portion of a chassis in a climbing direction away from a ground reference plane can be accomplished in a variety of ways. In a first way, the oscillation speed of the wing members in the “front” is increased relative to the oscillation speed of the wing members in the “back.” As used in herein, “front” denotes the wing members that are forward of the center of gravity of the chassis, wherein forward is used to denote a direction of travel. As used herein, “back” denotes the wing members that are rearward of the center of gravity of the chassis. In a second way, a pitch angle of the “front” wing members is increased relative to a pitch angle of the “rear” wing members. In a third way, the motion of the “front” wing members is altered to move in more of a hover than the motion of the “rear” wing members.

In another example, pitching the front portion of a chassis down in a descending direction toward a ground reference plane can be accomplished in a variety of ways. In a first way, the oscillation speed of the wing members in the “front” is decreased relative to the oscillation speed of the wing members in the “back.” In a second way, a pitch angle of the “front” wing members is decreased relative to the pitch angle of the “rear” wing members. In a third way, the motion of the “rear” wing members is altered to be more of a hover than the motion of the “front” wing members.

A number of maneuvers through a fluid has been described with the use of the preceding figures. Those of skill in the art will recognize that additional maneuvers are possible within the description of embodiments presented herein. Accordingly, all such maneuvers through a fluid are considered to be within the scope of this description of embodiments.

The apparatuses and methods described herein are readily adapted to a variety of fluids such as air, water, etc. As such, wing areas and oscillation speeds of the wing members will be adjusted to produce a required amount of lift and propulsive force necessary to move a particular chassis in or through a particular fluid. Those of skill in the art will appreciate that, in general, less dense fluids such as air will require more wing area, more wing members, higher oscillation speeds, etc. than more dense fluids such as water.

For purposes of discussing and understanding this description, it is to be understood that various terms are used by those knowledgeable in the art to describe techniques and approaches. Furthermore, in this description for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding. It will be evident, however, to one of ordinary skill in the art, that embodiments of the invention may be practiced without these specific details. In some instances, well-known structures and devices are shown in simplified form, rather than in detail, in order to avoid obscuring embodiments of the invention. These embodiments are described in sufficient detail to enable those of ordinary skill in the art to practice the invention, and it is to be understood that other embodiments may be utilized and that logical, mechanical, electrical, and other changes may be made without departing from the scope of the invention.

As used in this description, “one embodiment” or “an embodiment” or similar phrases means that the feature(s) being described is included in at least one embodiment of the invention. References to “one embodiment” in this description do not necessarily refer to the same embodiment; however, neither are such embodiments mutually exclusive. Nor does “one embodiment” imply that there is but a single embodiment of the invention. For example, a feature, structure, act, etc. described in “one embodiment” may also be included in other embodiments. Thus, the invention may include a variety of combinations and/or integrations of the embodiments described herein.

While the invention has been described in terms of several embodiments, those of skill in the art will recognize that the invention is not limited to the embodiments described, but can be practiced with modification and alteration within the spirit and scope of the appended claims. Thus, the description is to be regarded as illustrative instead of limiting and the scope of the invention is defined only by the appended claims.