EP2038602A2

EP2038602A2 - Two-axis trajectory control system

Info

Publication number: EP2038602A2
Application number: EP07873817A
Authority: EP
Inventors: Johnny E. Banks
Original assignee: Lockheed Corp; Lockheed Martin Corp
Current assignee: Lockheed Martin Corp
Priority date: 2006-07-07
Filing date: 2007-07-06
Publication date: 2009-03-25
Also published as: US20080006736A1; WO2008105899A2; WO2008105899A3

Abstract

A trajectory control system includes a first control mechanism having a pair of outputs operably associated with a first pair of control surfaces, the first control mechanism operable to articulate the first pair of control surfaces in unison and a second control mechanism having a pair of outputs operably associated with a second pair of control surfaces, the second control mechanism operable to articulate the second pair of control surfaces in unison. The second control mechanism is nested in the first control mechanism such that the pair of outputs of the first control mechanism is substantially coplanar with the pair of outputs of the second control mechanism.

Description

TWO-AXIS TRAJECTORY CONTROL SYSTEM

Technical Field

The present invention relates to systems for controlling the trajectory of airborne or waterborne vehicles.

Description of the Prior Art

Airborne or waterborne vehicles, such as missiles, rockets, torpedoes, and the like, are often used to deliver a payload to a target location or to carry a payload over a desired area. For example, vehicles may be used in combat situations to deliver a payload, such as an explosive warhead or a kinetic energy penetrator, to a target to disable or destroy the target. Surveillance vehicles may carry a payload designed to sense certain conditions surrounding the vehicle, such as objects on the ground or weather activity. Such a vehicle typically includes a trajectory control system having a plurality of control surfaces, such as fins, canards, flares, etc., that are articulated by a system to control the vehicle's direction and attitude.

Some vehicles are large in size and, thus, can accommodate large systems for articulating the vehicle's control surfaces. A large articulation system, however, may not be desirable, because less volume of the vehicle is available for propellant and payload. A smaller vehicle may simply not be viable for the purpose intended for the vehicle if the articulation system occupies a large percentage of the vehicle's volume. For example, a smaller vehicle may not be able to reach a desired target or may not be capable of carrying sufficient payload if the articulation system occupies a large volume percentage of the vehicle. Outer diameters of some projectile-type vehicles, such as rockets and missiles, are constrained in size by the type of equipment used to launch the vehicle. For example, "shoulder-launched" vehicles or vehicles launched from personnel carriers often are limited in outer diameter, as well as overall size. Larger, conventional articulation systems for control surfaces are not well suited for use in such vehicles. Other conventional trajectory control systems provide articulation systems that move each of the control surfaces independently to provide control over roll, pitch, and yaw. In some operational environments, vehicle roll is not a concern. In other words, it is not important that the roll orientation of the vehicle be maintained during operation of the vehicle. Using a trajectory control system that provides roll control when the vehicle roll is not important unduly adds to the cost, complexity, and weight of the vehicle.

Conventional two-axis trajectory control systems that control pitch and yaw of a vehicle are not sufficiently compact to lend their use in smaller vehicles. Moreover, such conventional two-axis trajectory control systems are not configured to withstand the extreme loads experienced during high velocity maneuvers, such as those employed by kinetic energy projectiles. Conventional two-axis trajectory control systems are typically complex, requiring many different components to be manufactured and assembled.

It is generally desirable, however, for such vehicles to be lighter in weight, rather than heavier, so that their ranges may be extended while using an equivalent amount of propellant. Further, it is generally desirable for the contents of the vehicle other than the payload, e.g., the motors, power transmission assemblies, and the like, to be more compact, so that larger payloads may be used within the body of the projectile. It is also often desirable to decrease the complexity of calculating the required orientation of the control surfaces to attain the desired vehicle orientation and commanding the actuation apparatuses to orient the control surfaces accordingly.

There are many designs of trajectory control systems well known in the art; however, considerable shortcomings remain.

Brief Description of the Drawings

The novel features believed characteristic of the invention are set forth in the appended claims. However, the invention itself, as well as a preferred mode of use, and further objectives and advantages thereof, will best be understood by reference to the following detailed description when read in conjunction with the accompanying drawings, in which the leftmost significant digit(s) in the reference numerals denote(s) the first figure in which the respective reference numerals appear, wherein:

Figure 1 is a partially exploded, perspective view of an illustrative embodiment of a two-axis control surface actuation system according to the present invention;

Figure 2 is a partially exploded, perspective view of the control surface actuation system of Figure 1 ;

Figure 3 is an exploded view of an illustrative embodiment of a control assembly of the control surface actuation system of Figure 1 ;

Figure 4 is a partially exploded, perspective view of an axle and related elements of the control surface actuation system of Figure 1 ;

Figure 5 is a partially exploded, perspective view of a vehicle incorporating the control surface actuation system of Figure 1 ;

Figure 6 is a cross-sectional view of a portion of the axle of Figure 4 take along line 6-6 of Figure 4;

Figure 7 is a perspective view of a control surface member according to the present invention;

Figure 8 is a partially exploded, perspective view of a portion of the vehicle of Figure 5; and

Figure 9 is a partially exploded, perspective view of the vehicle of Figure 5.

While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof have been shown by way of example in the drawings and - A -

are herein described in detail. It should be understood, however, that the description herein of specific embodiments is not intended to limit the invention to the particular forms disclosed, but on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the appended claims.

Description of the Preferred Embodiment

Illustrative embodiments of the invention are described below. In the interest of clarity, not all features of an actual implementation are described in this specification. It will of course be appreciated that in the development of any such actual embodiment, numerous implementation-specific decisions must be made to achieve the developer's specific goals, such as compliance with system-related and business-related constraints, which will vary from one implementation to another. Moreover, it will be appreciated that such a development effort might be complex and time-consuming but would nevertheless be a routine undertaking for those of ordinary skill in the art having the benefit of this disclosure.

In the specification, reference may be made to the spatial relationships between various components and to the spatial orientation of various aspects of components as the devices are depicted in the attached drawings. However, as will be recognized by those skilled in the art after a complete reading of the present application, the devices, members, apparatuses, etc. described herein may be positioned in any desired orientation. Thus, the use of terms such as "above," "below," "upper," "lower," or other like terms to describe a spatial relationship between various components or to describe the spatial orientation of aspects of such components should be understood to describe a relative relationship between the components or a spatial orientation of aspects of such components, respectively, as the device described herein may be oriented in any desired direction. The present invention represents a two-axis system for controlling the trajectory of an airborne or waterborne vehicle. In particular, the present system articulates a plurality of control surfaces, such as a plurality of fins, to adjust the pitch and/or yaw of the vehicle. As used in the present application, the term "control surface" means a structure, such as an airfoil, that is moveable to control or guide an airborne or waterborne vehicle. In a preferred embodiment, the present system includes a housing that encloses a first control mechanism, operably associated with a first pair of control surfaces, and a second control mechanism, operably associated with a second pair of control surfaces. The control mechanisms nest with respect to one another such that the output shafts of the control mechanisms are coplanar. Preferably, the control mechanisms are identical in configuration to reduce the cost and complexity of the system. The control mechanisms are disposed in different portions of a housing. Each of the control mechanisms and the housing portion corresponding to the control mechanism forms a control assembly. The control assemblies mate with one another to form a control surface actuation system.

Figures 1 and Figure 2 provide partially exploded, perspective views of an illustrative embodiment of a two-axis control surface actuation system 101 according to the present invention. Control surface actuation system 101 comprises a housing 103, a first control mechanism 105, a second control mechanism 107, and a plurality of locking rings 109. Housing 103 comprises a first portion 111 in which first control mechanism 105 is disposed and a second portion 113 in which second control mechanism 107 is disposed. First portion 111 and first control mechanism 105 make up a first control assembly 115. Second portion 113 and second control mechanism 107 make up a second control assembly 117. Control lines 119 extend between trajectory control mechanisms 105, 107 and, for example, a guidance computer for the vehicle.

Locking rings 109 engage first portion 11 1 of housing 103 and second portion 113 of housing 103 to retain first portion 111 to second portion 113. As control mechanisms 105, 107 are disposed in portions 111 , 113, respectively, locking rings 109 retain first control assembly 115 to second control assembly 117. By way of example and illustration, locking rings 109 are but one means for retaining first portion 111 of housing 103 to second portion 113 of housing 103. Moreover, locking rings 109 are but one means for retaining first control assembly 115 to second control assembly 117. Each of first control mechanism 105 and second control mechanism 107 are configured to mate with and articulate a pair of control surfaces (not shown in Figures 1 or 2), as will be discussed in greater detail below. Moreover, first control mechanism 105 and second control mechanism 107 are configured to mate with one another, as will also be described in greater detail below.

In the illustrated embodiment, first portion 111 of housing 103 and first control mechanism 105 are substantially equivalent in construction to second portion 113 of housing 103 and second control mechanism 107, respectively. In other words, first portion 11 1 of housing 103 is substantially equivalent in construction to second portion 113 of housing 103 and first control mechanism 105 is substantially equivalent in construction to second control mechanism 107. Accordingly, first control assembly 115 is, preferably, substantially equivalent in construction to second control assembly 117. It should be noted that the embodiment illustrated in Figures 1 and 2 is merely preferred. Other embodiments are contemplated by the present invention wherein first control assembly 115 is different in construction from second control assembly 117. For example, first portion 1 11 of housing 103 may differ in construction from second portion 113 of housing 103, so long as first portion 111 can be retained to second portion 113. In another example, first control mechanism 105 may differ in construction from second control mechanism 107, so long as first control mechanism 105 and second control mechanism 107 mate with one another or the outputs of first control mechanism 105 and second control mechanism 107 are coplanar. It should be noted that first portion 111 of housing 103 (and, thus, first control mechanism 105) is clocked at about 90 degrees with respect to second portion 113 of housing (and, thus second control mechanism 107), as illustrated in Figure 2. Figure 3 provides an exploded view of first portion 111 of housing 103 and first control mechanism 105. As the preferred embodiment of the present invention contemplates second control assembly 117 to be substantially equivalent in construction as first control assembly 115, the following description of first control assembly 115 applies equally to second control assembly 1 17. It should be noted that components of second control assembly 1 17, when referenced herein, are referred to by the corresponding element reference number of first control assembly 115, followed by the prime mark. For example, as will be discussed below, first control mechanism 105 comprises an end cover 301. In the preferred embodiment, second control mechanism 107 comprises an end cover 301 ' having a construction corresponding to end cover 301.

First control mechanism 105, in the illustrated embodiment, comprises end cover 301 , bearings 303a-303f, a rotor 305, a stator 307, a motor gear 309, a worm drive gear 311 , a worm shaft 313, a worm shaft end stop 315, an axle drive nut 317, and an axle 319. Rotor 305 and stator 307 make up a motor 321 that, when powered and activated, provides the motive force for actuating first control mechanism 105. Rotor 305 is rotatably supported by end cover 301 via bearing 303a. Rotor 305 is also rotatably supported by first portion 111 of housing 103 via bearing 303b. Rotor 305 comprises a rotor shaft 323 fixedly coupled with motor gear 309. Motor gear 309 is engaged with worm drive gear 311 , such that worm drive gear 311 rotates when motor 321 rotates. Worm drive gear 311 is fixedly coupled with worm shaft 313, such that worm shaft 313 rotates when worm drive gear 311 rotates. Worm shaft 313 is rotatably supported by first portion 111 of housing 103 via bearing 303c. Worm shaft end stop 315 is fixedly coupled with worm shaft 313.

Still referring to Figure 3, worm shaft end stop 315 is rotatably supported by second portion 113 (not shown in Figure 3 but shown in Figures 1 and 2) of housing 103 via a bearing 303d' (shown in Figure 2) of second control mechanism 107. A worm shaft end stop 315' (shown in Figure 2) of second control mechanism 107 is rotatably supported by first portion 111 of housing 103 via bearing 303d. The coupling of worm shaft end stop 315 to second portion 113 of housing 103 via bearing 303d' in combination with the coupling of worm shaft end stop 315' to first portion 11 1 of housing 103 via bearing 303d is but one means for mating first control assembly 115 to second control assembly 117. Moreover, the coupling of worm shaft end stop 315 to second portion 113 of housing 103 via bearing 303d' in combination with the coupling of worm shaft end stop 315' to first portion 111 of housing 103 via bearing 303d is but one means for mating first control mechanism 105 to second control mechanism 107.

Axle drive nut 317 is engaged with worm shaft 313, such that axle drive nut 317 traverses along worm shaft 313 when worm shaft 313 rotates. Axle drive nut 317 is coupled with a clevis 325 of axle 319, such that axle 319 rotates about a longitudinal axis 327 of axle as axle drive nut 317 traverses along worm shaft 313. It should be noted that axle drive nut 317 is coupled with clevis 325 of axle 319 so that axle drive nut 317 rotates about an axis 329 that is substantially parallel to axis 327. In the present embodiment, as best illustrated in Figure 4, axle drive nut 317 comprises an upwardly extending pin 401 a and a downwarly extending pin 401 b. Pins 401 a and 401 b each define a groove 403a and 403b, respectively, configured to receive one of spring clips 405a and 405b, respectively. Bushings 407a and 407b each define an opening 409a and 409b, respectively. Pin 401 a is disposed through opening 409a of bushing 407a and spring clip 405a is placed in groove 403a of pin 401 a to retain bushing 407a on axle drive nut 317. Pin 401 b is disposed through opening 409b of bushing 407b and spring clip 405b is placed in groove 403b of pin 401 b to retain bushing 407b on axle drive nut 317. Bushing 407a is disposed in a recess 411 a of an upper arm 413a of clevis 325. Bushing 407b is disposed in a recess 411 b of a lower arm 413b of clevis 325. Bushings 407a and 407b are retained in recesses 411 a and 41 1 b, respectively via the engagement of axle drive nut 317 and worm shaft 313 when first control assembly 1 15 is mated with second control assembly 117. Note also that axle 319 includes a bend, generally at 419, that is configured to receive axle 319' (shown in Figure 2). Preferably axle 319' has a configuration corresponding to axle 319, such that axles 319 and 319' nest with respect to one another generally at bend 419 of axle 319 and the corresponding bend of axle 319'. Such a configuration conserves the volume required for control surface actuation system 101. Accordingly, longitudinal axis 327 of axle 319 and longitudinal axis 327' (shown in Figure 2) of axle 319' (and, thus, the outputs of control mechanisms 105 and 107) are substantially coplanar.

Returning now to Figure 3, axle 319 is rotatably supported by first portion 111 of housing 103 and second portion 113 (shown in Figures 1 and 2) of housing 103 via bearings 303e and 303f when locking rings 109 are engaged with first portion 111 and second portion 113. Accordingly, when power is applied to motor 321 and motor 321 is activated via control lines 119, rotor shaft 323 rotates, which, in turn rotates motor gear

309. Motor gear 309 rotates worm drive gear 311 , which, in turn, rotates worm shaft 313. Worm shaft 313 advances axle drive nut 317 along worm shaft 313, which, in turn, rotates axle 319 about longitudinal axis 317.

Figure 5 depicts one particular embodiment of a trajectory control system 501 according to the present invention. In the illustrated embodiment, trajectory control system 501 comprises a plurality of control surface members 503a-503d operably associated with control surface actuation system 101. Control surface members 503a- 503d each comprises a corresponding shaft 505a-505d extending from a control surface 507a-507d. Shafts 505a and 505b are coupled with axle 319 of first control mechanism 105, while shafts 505c and 505d are coupled with axle 319' (shown in Figure 2) of second control mechanism 107. In the particular embodiment illustrated in Figure 5, control surfaces 507a-507d are fins. The scope of the present invention, however, is not so limited. Rather, control surfaces 507a-507d may exhibit other forms, such as flares, canards, or the like. First control mechanism 105 is actuated to articulate control surfaces 507a, 507b in unison, via shafts 505a, 505b, respectively, and change the yaw (indicated by an arrow 508a) of a vehicle 509 comprising trajectory control system 501. Second control mechanism 107 is actuated to articulate control surfaces 507c, 507d in unison, via shafts 505c, 505d, to change the pitch (indicated by an arrow 508b) of vehicle 509. It should be noted that, in a preferred embodiment, longitudinal axis 327 of axle 319 is substantially coplanar with a longitudinal axis 327' (shown in Figure 2) of axle 319'. Accordingly, outputs of axles 319 and 319' (and, thus, the outputs of control mechanisms 105 and 107) are coplanar in such a preferred embodiment.

Referring to Figures 3, 5, and 6, axle 319 of first control mechanism 105 comprises couplings 331 a and 331 b that are adapted to mate with control surface members 503a and 503b, respectively. Axle 319' (shown in Figure 2) of second control mechanism 107 comprises couplings 331 a' and 331 b' (also shown in Figure 2) that are adapted to mate with control surface members 503c and 503d, respectively. The following description pertains particularly to axle 319 and coupling 331 a thereof. It should be noted, however, that the construction of coupling 331 b corresponds to the construction of coupling 331 a in the preferred embodiment. Moreover, the construction of axle 319' corresponds to the construction of axle 319 in the preferred embodiment.

Reference is now made to axle 319 of Figure 4, the cross-sectional view of coupling 331 a of Figure 6, and control surface member 503a of Figure 7. Coupling 331 a defines a groove 601 (shown in Figure 6) configured to receive a retainer 701 (shown in Figure 7) attached to shaft 505a of control surface member 503a. Retainer 701 retains shaft 505a in coupling 331 a. Shaft 505a defines a groove 703 that, when aligned with a passageway 415a defined by coupling 331 a, receives a pin 417a. Coupling 331 b defines a corresponding passageway 415b. An interface between pin 417a, coupling 331a, and shaft 505a, provides a base orientation of control surface member 503a with respect to first control assembly 115. It should be noted that, in the preferred embodiment, control surface member 503b is retained in coupling 331 b and is provided with a base orientation with respect to first control assembly 115 in the same manner as discussed above in relation to control surface member 503a. Referring to Figure 3, in the preferred embodiment, control surface member 503c is retained in coupling 331 a' and control surface member 503d is retained in coupling 331 b' in the same way as described above in relation to control surface member 503a. Moreover, in the preferred embodiment, control surface members 503c and 503d are provided with base orientations with respect to second control assembly 117 in the same way as discussed above concerning control surface member 503a.

Referring again to Figure 3, first control mechanism 105 further comprises a position sensor 333 that senses the position of one or more other components of first control mechanism 105 to determine the orientation of control surface members 503a and 503b with respect to first control assembly 115. In various embodiments, position sensor 333 comprises a Hall-effect sensor, a photodiode-type sensor, or the like, that senses teeth of motor gear 309. In one embodiment, position sensor 333 outputs a signal, for each tooth of motor gear 309 sensed, to a controller, such as the guidance computer, so that the controller can determine the orientation of control surface members 503a and 503b with respect to first control assembly 115. Note that, in a preferred embodiment, second control mechanism 107 comprises a corresponding position sensor (not shown) that operates in the same way as position sensor 333. It should be noted, however, that such position sensors are merely examples of a means for sensing an orientation of a pair of control surfaces {e.g., control surfaces 507a, 507b or control surfaces 507c, 507d) or a pair of control surface members {e.g., control surface members 503a, 503b or control surface members 503c, 503d) according to the present invention. Other constructions of such a means are possible and encompassed within the scope of the present invention.

Referring again to the particular embodiment of Figure 5, control surface actuation system 101 is operably associated with a body 511 of vehicle 509 by sliding, as indicated by arrow 519, control surface actuation system 101 into a cavity 513 defined by body 511. With control surface actuation system 101 disposed in cavity 513, as shown in Figure 8, pins 801 are inserted through pin openings 515 defined by body 511 and into pin openings 121 defined by housing 103. By way of example and illustration, pins 801 are but one means for retaining control surface actuation system 101 in body 511 of vehicle 509. Moreover, mechanical loads experienced during operation of vehicle 509 are efficiently transmitted from control surface members 503a- 503d, through control surface actuation system 101 , to body 511. As illustrated in Figure 9, control surface members 503a-503d are then inserted into couplings 331 a- 331 d through openings 517 defined by body 511 , such that retainers 701 are received in grooves 403 defined by couplings 331 a-331d to retain control surface members 503a-503d in couplings 331 a-331 d and pins {e.g., pins 417a and 417b) are received in grooves 601 of shafts 505a-505d to provide base orientations for control surface members 503a-503d.

The present invention provides significant advantages, including: (1 ) providing a two-axis trajectory control system that occupies a smaller volume of a vehicle than conventional trajectory control systems; (2) providing a two-axis trajectory control system that is less complex in construction than conventional trajectory control systems; and (3) providing a two-axis trajectory control system that can withstand the loadings experienced during high velocity vehicle operation.

The particular embodiments disclosed above are illustrative only, as the invention may be modified and practiced in different but equivalent manners apparent to those skilled in the art having the benefit of the teachings herein. Furthermore, no limitations are intended to the details of construction or design herein shown, other than as described in the claims below. It is therefore evident that the particular embodiments disclosed above may be altered or modified and all such variations are considered within the scope and spirit of the invention. Accordingly, the protection sought herein is as set forth in the claims below. It is apparent that an invention with significant advantages has been described and illustrated. Although the present invention is shown in a limited number of forms, it is not limited to just these forms, but is amenable to various changes and modifications without departing from the spirit thereof.

Claims

1. A two-axis trajectory control system, comprising: a first control mechanism having a pair of outputs operably associated with a first pair of control surfaces, the first control mechanism operable to articulate the first pair of control surfaces in unison; and a second control mechanism having a pair of outputs operably associated with a second pair of control surfaces, the second control mechanism operable to articulate the second pair of control surfaces in unison; wherein the second control mechanism is nested in the first control mechanism such that the pair of outputs of the first control mechanism is substantially coplanar with the pair of outputs of the second control mechanism.

2. The two-axis trajectory control system, according to claim 1 , further comprising: a housing comprising a first portion in which the first control mechanism is disposed and a second portion, mated with the first portion, in which the second control mechanism is disposed; and means for retaining the first portion to the second portion; wherein the first control mechanism and the second control mechanism are each supported by the first portion of the housing and the second portion of the housing.

3. The two-axis trajectory control system, according to claim 1 , further comprising: a position sensor operably associated with one of the first control mechanism and the second control mechanism.

4. The two-axis trajectory control system, according to claim 1 , wherein the first control mechanism has a construction substantially equivalent to the second control mechanism.

5. The two-axis trajectory control system, according to claim 1 , operably associated with one of an airborne and a waterborne vehicle.

6. A two-axis trajectory control system, comprising: a first control mechanism having outputs coupled with a first pair of control surfaces, the first control mechanism operable to articulate the first pair of control surfaces in unison; and a second control mechanism having outputs coupled with a second pair of control surfaces, the second control mechanism operable to articulate the second pair of control surfaces in unison; wherein the first control mechanism comprises: a motor; an axle coupled with the first pair of control surfaces; and a worm shaft operably associated with the motor and the axle, such that the axle rotates when the motor is activated; and wherein the outputs of the first control mechanism are substantially coplanar with the outputs of the second control mechanism.

7. The two-axis trajectory control system, according to claim 6, wherein the first control mechanism further comprises: a motor gear fixedly attached to the motor; a worm drive gear fixedly attached to the worm shaft and engaged with the motor gear, such that the worm shaft rotates when the motor is actuated.

8. The two-axis trajectory control system, according to claim 6: wherein the axle includes a clevis; and wherein the first control mechanism further comprises: an axle drive nut engaged with the worm shaft and rotatably attached to the clevis of the axle.

9. The two-axis trajectory control system, according to claim 8, wherein the axle drive nut rotates with respect to the axle about a first axis and the axle rotates about a second axis, which is substantially parallel to the first axis, when the motor is actuated.

10. The two-axis trajectory control system, according to claim 6, further comprising: a housing having a first portion in which the first control mechanism is disposed and a second portion in which the second control mechanism is disposed; wherein the first control mechanism is disposed in the first portion of the housing and the worm shaft is supported by both the first portion and the second portion of the housing.

1 1. The two-axis trajectory control system, according to claim 10, wherein the second control mechanism is disposed in the second portion of the housing and is supported by both the first portion and the second portion of the housing.

12. The two-axis trajectory control system, according to claim 6, wherein the second control mechanism includes an axle and the axle of the first control mechanism includes a bend configured to receive the axle of the second control mechanism.

13. The two-axis trajectory control system, according to claim 12, wherein the axle of the second control mechanism includes a bend, such that the axle of the first control mechanism is nested with respect to the axle of the second control mechanism at the bends of the axles.

14. A two-axis trajectory control system, comprising: a first control assembly operably associated with a first pair of control surfaces for articulating the first pair of control surfaces in unison; and a second control assembly operably associated with a second pair of control surfaces for articulating the second pair of control surfaces in unison, the second control assembly comprising: a housing portion; an end cap attached to the housing portion; a motor rotatably supported by the housing portion and the end cap, the motor having an output shaft; a motor gear fixedly attached to the output shaft of the motor; a worm drive gear engaged with the motor gear; a worm shaft rotatably supported by the housing portion and engaged with the worm drive gear; a worm shaft end stop fixedly attached to the worm shaft and rotatably supported by the first control assembly; an axle drive nut engaged with the worm shaft; and an axle coupled with the axle drive nut and the second pair of control surfaces.

15. The two-axis trajectory control system, according to claim 14, wherein the first control assembly comprises: a housing portion, such that the worm shaft end stop is rotatably supported by the housing portion of the first control assembly.

16. The two-axis trajectory control system, according to claim 14, wherein the construction of the first control assembly corresponds to the construction of the second control assembly.

17. The two-axis trajectory control system, according to claim 16, wherein a worm shaft end stop of the first control assembly is rotatably supported by the second control assembly.

18. The two-axis trajectory control system, according to claim 14, wherein the first control assembly comprises: an axle operably associated with the first pair of control surfaces; wherein the axle of the second control assembly includes a bend for receiving the axle of the first control assembly.

19. The two-axis trajectory control system, according to claim 18, wherein the axle of the first control assembly includes a bend for receiving the axle of the second control assembly.

20. The two-axis trajectory control system, according to claim 14, wherein the axle drive nut rotates with respect to the axle about an axis that is substantially parallel with an axis of rotation of the axle when the motor is activated.

21. The two-axis trajectory control system, according to claim 14, further comprising means for retaining the first control assembly to the second control assembly.