US20220120544A1 - Low inertia rolling control actuation system - Google Patents
Low inertia rolling control actuation system Download PDFInfo
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- US20220120544A1 US20220120544A1 US17/269,157 US201917269157A US2022120544A1 US 20220120544 A1 US20220120544 A1 US 20220120544A1 US 201917269157 A US201917269157 A US 201917269157A US 2022120544 A1 US2022120544 A1 US 2022120544A1
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- 241000272517 Anseriformes Species 0.000 claims abstract description 55
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Classifications
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F42—AMMUNITION; BLASTING
- F42B—EXPLOSIVE CHARGES, e.g. FOR BLASTING, FIREWORKS, AMMUNITION
- F42B10/00—Means for influencing, e.g. improving, the aerodynamic properties of projectiles or missiles; Arrangements on projectiles or missiles for stabilising, steering, range-reducing, range-increasing or fall-retarding
- F42B10/60—Steering arrangements
- F42B10/62—Steering by movement of flight surfaces
- F42B10/64—Steering by movement of flight surfaces of fins
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F42—AMMUNITION; BLASTING
- F42B—EXPLOSIVE CHARGES, e.g. FOR BLASTING, FIREWORKS, AMMUNITION
- F42B15/00—Self-propelled projectiles or missiles, e.g. rockets; Guided missiles
- F42B15/01—Arrangements thereon for guidance or control
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F41—WEAPONS
- F41G—WEAPON SIGHTS; AIMING
- F41G7/00—Direction control systems for self-propelled missiles
- F41G7/20—Direction control systems for self-propelled missiles based on continuous observation of target position
- F41G7/22—Homing guidance systems
- F41G7/2246—Active homing systems, i.e. comprising both a transmitter and a receiver
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F41—WEAPONS
- F41G—WEAPON SIGHTS; AIMING
- F41G7/00—Direction control systems for self-propelled missiles
- F41G7/20—Direction control systems for self-propelled missiles based on continuous observation of target position
- F41G7/22—Homing guidance systems
- F41G7/2253—Passive homing systems, i.e. comprising a receiver and do not requiring an active illumination of the target
Definitions
- Conventional missiles, or projectiles typically contain four canards configured as two canard sets, namely a horizontal pair of fins and a vertical pair of fins. Generally, these canard sets are located on the rear of a projectile.
- the four control fin-like surfaces act as part of the projectile's control actuation system (CAS) and aid in the stabilization of and the guidance for the projectile while in flight.
- CAS control actuation system
- canards may be controlled by either two or four motors thereby driving the cost of the CAS up due to the number of components required to outfit the CAS.
- the number of components also decreases the reliability of the subsystems and requires more dimensional volume when the CAS is in the stowed position, e.g., while in the launch tube. All of these factors, in part, play into reducing the system performance and increasing the system costs.
- One aspect of the present disclosure is a low inertia, rolling control actuation system, comprising: a projectile having a front portion and a rear portion; a control actuation system located between the front portion and the rear portion of the projectile, the control actuation system having only two canards; at least one bearing set being located between the control actuation system and the front portion, the rear portion, or both to decouple the control actuation system from the inertia of the front portion, the rear portion, or both the front portion and the rear portion of the projectile; and at least one canard control motor.
- the low inertia, rolling control actuation system further comprises a non-transitory computer-readable storage medium with a set of instructions encoded thereon to aid in guidance and navigation of the system.
- the low inertia, rolling control actuation system further comprises at least one brake.
- the low inertia, rolling control actuation system further comprises an angle measuring device.
- the low inertia, rolling control actuation system further comprises an inertial measuring unit.
- the low inertia, rolling control actuation system is wherein the at least one bearing set is two bearing sets, a first being located between the front portion and the control actuation system and the second being located between the rear portion and the control actuation system.
- the front portion comprises a warhead.
- the low inertia, rolling control actuation system further comprises a sensor suite in the front portion.
- the sensor suite comprises one or more of the following: a LWIR imager, a SWIR imager, a Visible imager, a GPS, an RF antenna, and a SAR antenna.
- the rear portion comprises a booster.
- Another aspect of the present disclosure is a method of guiding a projectile with a low inertia, rolling control actuation system, comprising: providing a projectile comprising: a front portion and a rear portion; a control actuation system located between the front portion and the rear portion of the projectile, the control actuation system having only two canards and at least one canard motor; and at least one bearing set being located between the control actuation system and the front portion, the rear portion, or both the front and the rear portion; decoupling the control actuation system from the inertia of the front portion, the rear portion, or both the front and rear portion of the projectile via the at least one bearing set; detecting one or more angle differentials between the control actuation system and the front portion, the rear portion, or both the front and rear portion of the projectile via an angle measuring device; moving the control actuation system into a radial direction using the control actuation system in a roll maneuver to set up for a course correction for the projectile by counter
- One embodiment of the method of guiding a projectile with a low inertia, rolling control actuation system is wherein the at least one bearing set is two bearing sets, a first being located between the front portion and the control actuation system and the second being located between the rear portion and the control actuation system.
- the front portion comprises a warhead and a sensor suite.
- the sensor suite comprises one or more of the following a LWIR imager, a SWIR imager, a Visible imager, a GPS, an RF antenna, and a SAR antenna.
- Yet another embodiment of the method of guiding a projectile with a low inertia, rolling control actuation system further comprises an inertial measuring unit for maintaining attitude of the one or more sensors during flight.
- FIG. 1 is a diagrammatic view of one embodiment of a low inertia, rolling mid body control actuation system for a projectile according to the principles of the present disclosure.
- FIG. 2 is a diagrammatic view of one embodiment of a low inertia, rolling front body control actuation system for a projectile according to the principles of the present disclosure.
- FIG. 3 is a cross-sectional view of one embodiment of a control actuation system for a projectile according to the principles of the present disclosure.
- FIG. 4 is a diagrammatic view of one embodiment of a low inertia, rolling control actuation system with two bearing sets for a projectile according to the principles of the present disclosure.
- FIG. 5 shows a flowchart of one embodiment of a method according to the principles of the present disclosure.
- One aspect of the present disclosure is a system comprising only two canards/control surfaces controlled by a single motor in the body of the weapon.
- the single motor and pair of canards are decoupled from the rear or the front of the projectile through a single bearing.
- the CAS/front section of the projectile is then moved into the proper roll position via an internal motor unit to apply the appropriate lift to maintain the projectile course.
- Another aspect of the present disclosure is a system comprising only two canards/control surfaces controlled by a single motor in the body of the weapon.
- the single motor and pair of canards are decoupled from the rear of the projectile and/or the front of the projectile through a pair of bearings.
- the CAS/front section is then moved into the proper roll position to apply the appropriate lift to maintain course utilizing a roll, then lift CAS guidance and control (GNC) system.
- GNC lift CAS guidance and control
- Yet another aspect of the present disclosure is a system comprising only two canards/control surfaces controlled by a single motor in the body of the weapon.
- the single motor and pair of canards are decoupled from the rear section of the projectile and/or the front section of the projectile through a pair of bearings.
- the CAS/front section is then moved into the proper roll position using an internal motor to change the roll position between the rear section and the front section.
- the system applies the appropriate lift to maintain course utilizing a roll, then lift CAS guidance and control (GNC) system.
- the front and the rear sections can structurally couple or decouple in the roll depending on the needs of the system. This flexibility allows true vertical stabilization between the airframe for navigation and for target imagers by providing for the ability to roll the CAS as an independent structure between the front and the rear sections.
- control actuation system (CAS) subsystem of a projectile is located at the mid body and is configured to roll independently from the warhead (e.g., the front of the projectile in the direction of flight) and the rocket motor (e.g., the rear of the projectile in the direction of flight).
- the two canards can quickly alter the roll orientation of the CAS relative to the remainder of the weapon and provide the proper course adjustments.
- the single canard pair is located at the front of the weapon.
- the reduction in parts reduces the cost of each projectile by approximately 40%, while providing a faster roll response since the CAS is completely decoupled to the weapon's inertia.
- reducing the CAS inertia by a factor between about 50 to about 100. This provides a faster response time due, in part, to the lower inertia and/or lower power consumption due to the smaller motors possible due to the lower load.
- Decoupling from the projectile's inertia is extremely important since a two canard system needs to roll prior to adding lift.
- the decoupling is used to insure that the lift is in the proper radial direction in order to null the radial error.
- the moment of inertia can be calculated using the following equation:
- I is in moment of inertia in lb.ft. 2
- W is weight in lbs
- K is the radius of gyration in ft.
- the inertia of the heavy subsystems reduce the response of the CAS to induce a roll and change its orientation.
- the mass of the system is lowered, in turn lowering the acceleration required. This is shown though the equation;
- a brake element is added between the front sensor suite and the booster/warhead (for a mid-body warhead).
- the CAS can be used to keep the sensor suite vertical by intermittent braking coupled with CAS roll corrections in a secondary control loop. This functionality provides the ability to keep imagers facing down for flight navigation. By maintain the face down flight navigation, the imagers can be used for guidance and navigation to the target.
- the sensor suite can include one or more sensors, including but not limited to a LWIR imager, a SWIR imager, a visible imager, a GPS, an RF antenna, a SAR antenna, or any suitable alternative.
- sensors including but not limited to a LWIR imager, a SWIR imager, a visible imager, a GPS, an RF antenna, a SAR antenna, or any suitable alternative.
- FIG. 1 depicts one embodiment of a low inertia, rolling mid-body control actuation system for a projectile 100 according to the principles of the present disclosure. More specifically, in this embodiment, the CAS 106 is sandwiched between the front section of the projectile 102 , and the rear section of the projectile 104 , via two bearing sets 110 , 112 .
- the low inertia design of this assembly allows responsive changes in roll position and eliminates the third and fourth canards of conventional CAS systems. In the present embodiment, there are only two canards 108 .
- the pair of canards 108 is located such that each canard is on an opposite side of the projectile body 100 such that they are axially aligned, and each canard is normal to the surface of the projectile body.
- the pair of canards 108 utilize only one canard control motor.
- each canard has a separate canard control motor to provide for differential rotation and to provide roll control.
- the separate motor per canard arrangement provides for coupled motion in the same direction to provide positive or negative lift of the projectile.
- the CAS canards move in opposite directions.
- lift the CAS canards move together in the same direction so both canards must be able to couple together depending on the amount of roll and lift that is needed at that moment.
- the GNC/CAS provides each canard, via its respective motor, a mixture of both roll and lift along the flight path depending on the particular need at that time in flight.
- the front of the projectile 102 in the direction of flight can include a warhead, a seeker and/or other sensors including a sensor suite.
- the rear of the projectile in the direction of flight 104 is the location of a rocket motor, or a booster.
- a single bearing 110 , or 112 is used to simplify the build.
- the roll control includes the inertia of the front of the projectile 102 or the rear of the projectile 104 .
- the front section typically contains the fuze and warhead.
- one or more sensors are employed either about the front portion or the mid-section of the projectile. When the target is quasi stationary (moving at about less than 5 to 10 MPH), this approach is the lowest cost solution.
- the CAS 106 in one embodiment is part of a precision guided kit that includes the GNC, sensors and associated hardware and software as a mid-section unit that is configured to be inserted into an unguided rocket thereby transforming the unguided rocket into a precision guided munition.
- FIG. 2 shows one embodiment of a low inertia, rolling front-body control actuation system for a projectile 200 according to the principles of the present disclosure.
- the control actuation system (CAS) subsystem of a projectile 208 is located proximate the front-body 204 and is configured to roll independently from the warhead 202 and independently from the rear of the projectile 206 (e.g. the rocket motor).
- the two canards 210 a and 210 b can quickly alter the roll orientation of the CAS relative to the remainder of the weapon and provide the proper course adjustments.
- a pair of bearings 212 , 214 is used to provide the independent rotatability of the CAS section.
- a single bearing 212 is used to simplify the build and the front portion is rotatable independent from the rear 206 .
- the cost of the projectile is increased, but the inertia of the CAS is further reduced by the inertia of the warhead, a seeker and possibly a front mounted sensor suite.
- the inertia reduction provides improved roll response time when the CAS rotates into the proper radial position to apply lift. This approach also allows engagement of UAVs and terrain vehicles (at about 30 to 50 MPH) that would not typically be considered possible using a standard roll/lift mid-body CAS.
- FIG. 3 depicts an axial cross-sectional view of one embodiment of a control actuation system for a projectile according to the principles of the present disclosure. More specifically, a single pair of canards is shown 300 a , 300 b .
- a simple brake is used to retain roll position about the projectile body 308 .
- the simple brake using a higher order control loop, would couple motion between the CAS and the front section containing a seeker.
- the brake is engaged to lock the CAS and the front section with the seeker, thereby using the CAS to orient the seeker's roll attitude.
- the brake would provide for intermittent coupling of the front section providing roll control when needed or decoupling it to perform a lift command in a different direction, thereby not affecting the attitude of the seeker. If the roll attitude of the seeker is not needed, the brake could eliminate the attitude and let the front section drift into a roll.
- the application of force 302 on the canard 300 a , 300 b can create positive lift 304 or negative lift 306 .
- the canard pair 300 a , 300 b rolls the CAS into the direction of travel and then applies either positive lift or negative lift. Since neither the front of projectile's inertia nor the rear of the projectile's inertia are coupled to the CAS, a higher level of response is feasible as it is rotates independently.
- the CAS in this example is separated from one or more sections of the projectile by the one or more bearing sets and provides an additional degree of freedom not found in standard CAS systems, which are generally tied directly to the front of the projectile.
- the second bearing set in a mid-body CAS provides the agility of a four canard system by incorporating elements of the standard approach.
- the two bearing sets, a mechanical brake between the front of the projectile and the CAS, and a rotational measurement method between the CAS and the front of the projectile is used.
- an inertial measurement unit IMU is installed to maintain attitude of the front of the projectile for target aim point.
- the CAS in some cases needs roll attitude relative to a vertical reference in order to execute the proper directional lift command that is maintained by the IMU.
- the angle measurement between the CAS and the seeker on the front of the projectile provides that roll attitude transfer.
- the angle can be measured with an angle measurement unit, for example but not limited to a magnetometer, an accelerometer, or a gyroscope.
- the mechanical brake provides the ability to couple both the CAS and the front of the projectile together to perform a roll correction during the flight to maintain a vertical attitude.
- the ability to point the antenna skyward offers better performance of the GPS subsystem.
- front of the projectile can be moved back and forth and function as a poor man's scanner to increase the field of regard (FOR) by two to ten times.
- Oscillator motion can be generated by the coupling and decoupling of the CAS from the front of the projectile.
- FIG. 4 depicts a diagrammatic view of one embodiment of a low inertia, rolling control actuation system with two bearing sets for a projectile according to the principles of the present disclosure. More specifically, a CAS 400 having only two canards 300 a , 300 b is shown. In this embodiment, a two bearing system is shown where a first bearing 402 decouples the CAS 400 from the front of the projectile 404 in the direction of flight. In one embodiment, the front of the projectile 404 comprises a warhead, fuze and/or a seeker. A second bearing set 406 decouples the CAS 400 from the rear of the projectile 408 in the direction of flight. In one embodiment, the rear of the projectile 408 comprises a rocket booster.
- an onboard processor receives location information and/or fire control information and utilizes that to drive the CAS to maintain a proper trajectory to successfully arrive at the target.
- the positional data received for the weapons, asset, and/or the target's position can be processed to generate the navigation and auto pilot commands needed to execute the mission.
- FIG. 5 depicts a flowchart 500 of one embodiment of a method or process according to the principles of the present disclosure. More specifically, a projectile with a low inertia, rolling control actuation system is provided 502 .
- the projectile has a front portion, a rear portion and has a control actuation system, which is located between the front portion and the rear portion of the projectile.
- the control actuation system has only two canards, and there is at least one bearing set being located between the control actuation system and the front portion, the rear portion, or both to decouple the control actuation system from the inertia of the front portion, the rear portion, or both the front portion and the rear portion of the projectile.
- there is only one motor in the CAS and in another, there is at least one motor per canard.
- the method 500 further includes decupling the control actuation system from the inertia of the front portion, the rear portion, or both the front and rear portion of the projectile via the at least one bearing set 504 .
- One or more angle differentials are detected between the control actuation system and the front portion, the rear portion, or both the front and rear portion of the projectile via an angle-measuring device 506 .
- the control actuation system moves in a radial direction using the control actuation system in a roll maneuver to set up for a course correction for the projectile by counter rotating the two canards of the control actuation system relative to the front, the rear, or both the front and the rear portion via the at least one bearing set and/or the motor and/or the brake 508 .
- Positive lift or negative lift is then applied to the control actuation system via the motor and/or the brake to complete a course correction of the projectile 510 .
- the computer readable medium as described herein can be a data storage device, or unit such as a magnetic disk, magneto-optical disk, an optical disk, or a flash drive.
- a data storage device or unit such as a magnetic disk, magneto-optical disk, an optical disk, or a flash drive.
- the term “memory” herein is intended to include various types of suitable data storage media, whether permanent or temporary, such as transitory electronic memories, non-transitory computer-readable medium and/or computer-writable medium.
- the invention may be implemented as computer software, which may be supplied on a storage medium or via a transmission medium such as a local-area network or a wide-area network, such as the Internet. It is to be further understood that, because some of the constituent system components and method steps depicted in the accompanying figures can be implemented in software, the actual connections between the systems components (or the process steps) may differ depending upon the manner in which the present invention is programmed Given the teachings of the present invention provided herein, one of ordinary skill in the related art will be able to contemplate these and similar implementations or configurations of the present invention.
- the present invention can be implemented in various forms of hardware, software, firmware, special purpose processes, or a combination thereof.
- the present invention can be implemented in software as an application program tangible embodied on a computer readable program storage device.
- the application program can be uploaded to, and executed by, a machine comprising any suitable architecture.
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Abstract
Description
- This application claims the benefit of U.S. Provisional Patent Application No. 62/741,024, filed Oct. 4, 2018, the content of which is incorporated by reference herein its entirety.
- Conventional missiles, or projectiles, typically contain four canards configured as two canard sets, namely a horizontal pair of fins and a vertical pair of fins. Generally, these canard sets are located on the rear of a projectile. The four control fin-like surfaces act as part of the projectile's control actuation system (CAS) and aid in the stabilization of and the guidance for the projectile while in flight.
- Conventional four control surfaces, canards, may be controlled by either two or four motors thereby driving the cost of the CAS up due to the number of components required to outfit the CAS. The number of components also decreases the reliability of the subsystems and requires more dimensional volume when the CAS is in the stowed position, e.g., while in the launch tube. All of these factors, in part, play into reducing the system performance and increasing the system costs.
- Wherefore it is an object of the present disclosure to overcome the above-mentioned shortcomings and drawbacks associated with conventional control actuation systems (CAS) for projectiles.
- One aspect of the present disclosure is a low inertia, rolling control actuation system, comprising: a projectile having a front portion and a rear portion; a control actuation system located between the front portion and the rear portion of the projectile, the control actuation system having only two canards; at least one bearing set being located between the control actuation system and the front portion, the rear portion, or both to decouple the control actuation system from the inertia of the front portion, the rear portion, or both the front portion and the rear portion of the projectile; and at least one canard control motor.
- In some embodiments the low inertia, rolling control actuation system further comprises a non-transitory computer-readable storage medium with a set of instructions encoded thereon to aid in guidance and navigation of the system.
- One embodiment of the low inertia, rolling control actuation system further comprises at least one brake. In one embodiment, the low inertia, rolling control actuation system further comprises an angle measuring device. In some cases, the low inertia, rolling control actuation system further comprises an inertial measuring unit.
- Another embodiment of the low inertia, rolling control actuation system is wherein the at least one bearing set is two bearing sets, a first being located between the front portion and the control actuation system and the second being located between the rear portion and the control actuation system. In some cases, the front portion comprises a warhead. In certain embodiments, the low inertia, rolling control actuation system further comprises a sensor suite in the front portion.
- In yet another embodiment of the low inertia, rolling control actuation system, the sensor suite comprises one or more of the following: a LWIR imager, a SWIR imager, a Visible imager, a GPS, an RF antenna, and a SAR antenna. In some cases, the rear portion comprises a booster.
- Another aspect of the present disclosure is a method of guiding a projectile with a low inertia, rolling control actuation system, comprising: providing a projectile comprising: a front portion and a rear portion; a control actuation system located between the front portion and the rear portion of the projectile, the control actuation system having only two canards and at least one canard motor; and at least one bearing set being located between the control actuation system and the front portion, the rear portion, or both the front and the rear portion; decoupling the control actuation system from the inertia of the front portion, the rear portion, or both the front and rear portion of the projectile via the at least one bearing set; detecting one or more angle differentials between the control actuation system and the front portion, the rear portion, or both the front and rear portion of the projectile via an angle measuring device; moving the control actuation system into a radial direction using the control actuation system in a roll maneuver to set up for a course correction for the projectile by counter rotating the two canards of the control actuation system relative to the front, the rear, or both the front and the rear portion via the at least one bearing set and/or the motor and/or the brake; and applying positive lift or negative lift to the control actuation system via the motor and/or the brake to complete a course correction of the projectile.
- One embodiment of the method of guiding a projectile with a low inertia, rolling control actuation system is wherein the at least one bearing set is two bearing sets, a first being located between the front portion and the control actuation system and the second being located between the rear portion and the control actuation system.
- Another embodiment of the method of guiding a projectile with a low inertia, rolling control actuation system is wherein the front portion comprises a warhead and a sensor suite. In some cases, the sensor suite comprises one or more of the following a LWIR imager, a SWIR imager, a Visible imager, a GPS, an RF antenna, and a SAR antenna.
- Yet another embodiment of the method of guiding a projectile with a low inertia, rolling control actuation system further comprises an inertial measuring unit for maintaining attitude of the one or more sensors during flight.
- These aspects of the disclosure are not meant to be exclusive and other features, aspects, and advantages of the present disclosure will be readily apparent to those of ordinary skill in the art when read in conjunction with the following description, appended claims, and accompanying drawings.
- The foregoing and other objects, features, and advantages of the disclosure will be apparent from the following description of particular embodiments of the disclosure, as illustrated in the accompanying drawings in which like reference characters refer to the same parts throughout the different views. The drawings are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the disclosure.
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FIG. 1 is a diagrammatic view of one embodiment of a low inertia, rolling mid body control actuation system for a projectile according to the principles of the present disclosure. -
FIG. 2 is a diagrammatic view of one embodiment of a low inertia, rolling front body control actuation system for a projectile according to the principles of the present disclosure. -
FIG. 3 is a cross-sectional view of one embodiment of a control actuation system for a projectile according to the principles of the present disclosure. -
FIG. 4 is a diagrammatic view of one embodiment of a low inertia, rolling control actuation system with two bearing sets for a projectile according to the principles of the present disclosure. -
FIG. 5 shows a flowchart of one embodiment of a method according to the principles of the present disclosure. - One aspect of the present disclosure is a system comprising only two canards/control surfaces controlled by a single motor in the body of the weapon. In some cases, the single motor and pair of canards are decoupled from the rear or the front of the projectile through a single bearing. In this embodiment, the CAS/front section of the projectile is then moved into the proper roll position via an internal motor unit to apply the appropriate lift to maintain the projectile course.
- Another aspect of the present disclosure is a system comprising only two canards/control surfaces controlled by a single motor in the body of the weapon. In some cases, the single motor and pair of canards are decoupled from the rear of the projectile and/or the front of the projectile through a pair of bearings. The CAS/front section is then moved into the proper roll position to apply the appropriate lift to maintain course utilizing a roll, then lift CAS guidance and control (GNC) system.
- Yet another aspect of the present disclosure is a system comprising only two canards/control surfaces controlled by a single motor in the body of the weapon. In some cases, the single motor and pair of canards are decoupled from the rear section of the projectile and/or the front section of the projectile through a pair of bearings. The CAS/front section is then moved into the proper roll position using an internal motor to change the roll position between the rear section and the front section. In one embodiment, the system applies the appropriate lift to maintain course utilizing a roll, then lift CAS guidance and control (GNC) system. The front and the rear sections can structurally couple or decouple in the roll depending on the needs of the system. This flexibility allows true vertical stabilization between the airframe for navigation and for target imagers by providing for the ability to roll the CAS as an independent structure between the front and the rear sections.
- In one embodiment of the present disclosure, the control actuation system (CAS) subsystem of a projectile is located at the mid body and is configured to roll independently from the warhead (e.g., the front of the projectile in the direction of flight) and the rocket motor (e.g., the rear of the projectile in the direction of flight). In one example, the two canards can quickly alter the roll orientation of the CAS relative to the remainder of the weapon and provide the proper course adjustments. In certain embodiments of the present disclosure, the single canard pair is located at the front of the weapon. Regardless of the placement of the pair of canards (front or mid-body), the reduction in parts reduces the cost of each projectile by approximately 40%, while providing a faster roll response since the CAS is completely decoupled to the weapon's inertia. Thus reducing the CAS inertia by a factor between about 50 to about 100. This provides a faster response time due, in part, to the lower inertia and/or lower power consumption due to the smaller motors possible due to the lower load.
- Decoupling from the projectile's inertia is extremely important since a two canard system needs to roll prior to adding lift. The decoupling is used to insure that the lift is in the proper radial direction in order to null the radial error. The moment of inertia can be calculated using the following equation:
-
I=WK 2 - where I is in moment of inertia in lb.ft.2, W is weight in lbs, and K is the radius of gyration in ft. The moment of inertia can then be used to calculate torque using the following equation:
-
τ=Iα - where τ is torque in ft.lb., and a is the angular acceleration in rotations per minute per minute. Combining the equations yields:
-
τ=WK 2α - When time is known the equation in this example becomes
-
τ=WK 2(Final RPM−Initial RPM)=307.6×acceleration time(seconds) - If the CAS is coupled to the front of the projectile, the back of the projectile, or both, for the same canard deflection generating a unit force to roll, the inertia of the heavy subsystems reduce the response of the CAS to induce a roll and change its orientation. By adding the bearing to decouple the CAS from the rest of the projectile the mass of the system is lowered, in turn lowering the acceleration required. This is shown though the equation;
-
F=m 1 a 1 ;F=100m 1 a 2 - Setting the forces equal and solving for a1 shows:
-
a 1=100a 2 - In other words, a
mass 100 times larger will yield 100 times less acceleration when acted upon by the same force. Thus, the added bearings to decouple the CAS from the rest of the projectile allows the CAS roll acceleration to increase by the ratio of mass or inertia. - From the equation above, if the booster, rear of the projectile, weighs 60 lbs., and the warhead, front of the projectile, weighs 30 lbs., while the CAS only weighs <2.0 lbs, the reduction on the CAS load to induce a roll before a lift command is reduced by (60+30)/2 or 45×. This is a considerable reduction. The freedom of moving the CAS while decoupling the booster and the warhead provides the agility needed to engage a mobile target that is typically reserved only for a four canard CAS.
- In one embodiment of the system of the present disclosure, a brake element is added between the front sensor suite and the booster/warhead (for a mid-body warhead). In this embodiment, the CAS can be used to keep the sensor suite vertical by intermittent braking coupled with CAS roll corrections in a secondary control loop. This functionality provides the ability to keep imagers facing down for flight navigation. By maintain the face down flight navigation, the imagers can be used for guidance and navigation to the target.
- The sensor suite can include one or more sensors, including but not limited to a LWIR imager, a SWIR imager, a visible imager, a GPS, an RF antenna, a SAR antenna, or any suitable alternative.
-
FIG. 1 depicts one embodiment of a low inertia, rolling mid-body control actuation system for a projectile 100 according to the principles of the present disclosure. More specifically, in this embodiment, theCAS 106 is sandwiched between the front section of the projectile 102, and the rear section of the projectile 104, via two bearing sets 110, 112. The low inertia design of this assembly allows responsive changes in roll position and eliminates the third and fourth canards of conventional CAS systems. In the present embodiment, there are only twocanards 108. The pair ofcanards 108 is located such that each canard is on an opposite side of theprojectile body 100 such that they are axially aligned, and each canard is normal to the surface of the projectile body. In one embodiment, the pair ofcanards 108 utilize only one canard control motor. - In one embodiment, each canard has a separate canard control motor to provide for differential rotation and to provide roll control. In some cases, the separate motor per canard arrangement provides for coupled motion in the same direction to provide positive or negative lift of the projectile. In a roll, the CAS canards move in opposite directions. In lift, the CAS canards move together in the same direction so both canards must be able to couple together depending on the amount of roll and lift that is needed at that moment. The GNC/CAS provides each canard, via its respective motor, a mixture of both roll and lift along the flight path depending on the particular need at that time in flight.
- Still referring to
FIG. 1 , in some embodiments the front of the projectile 102 in the direction of flight can include a warhead, a seeker and/or other sensors including a sensor suite. In other embodiments, the rear of the projectile in the direction offlight 104 is the location of a rocket motor, or a booster. In some embodiments, asingle bearing - The
CAS 106 in one embodiment is part of a precision guided kit that includes the GNC, sensors and associated hardware and software as a mid-section unit that is configured to be inserted into an unguided rocket thereby transforming the unguided rocket into a precision guided munition. -
FIG. 2 shows one embodiment of a low inertia, rolling front-body control actuation system for a projectile 200 according to the principles of the present disclosure. More specifically, the control actuation system (CAS) subsystem of a projectile 208 is located proximate the front-body 204 and is configured to roll independently from thewarhead 202 and independently from the rear of the projectile 206 (e.g. the rocket motor). In one example, the twocanards bearings single bearing 212 is used to simplify the build and the front portion is rotatable independent from the rear 206. In the embodiment with two bearingsets -
FIG. 3 depicts an axial cross-sectional view of one embodiment of a control actuation system for a projectile according to the principles of the present disclosure. More specifically, a single pair of canards is shown 300 a, 300 b. In one example, a simple brake is used to retain roll position about theprojectile body 308. In certain embodiments, the simple brake, using a higher order control loop, would couple motion between the CAS and the front section containing a seeker. In one embodiment, the brake is engaged to lock the CAS and the front section with the seeker, thereby using the CAS to orient the seeker's roll attitude. In on embodiment, the brake would provide for intermittent coupling of the front section providing roll control when needed or decoupling it to perform a lift command in a different direction, thereby not affecting the attitude of the seeker. If the roll attitude of the seeker is not needed, the brake could eliminate the attitude and let the front section drift into a roll. - Still referring to
FIG. 3 , the application offorce 302 on thecanard positive lift 304 ornegative lift 306. In one embodiment of the system of the present disclosure, thecanard pair - The CAS in this example is separated from one or more sections of the projectile by the one or more bearing sets and provides an additional degree of freedom not found in standard CAS systems, which are generally tied directly to the front of the projectile. In one embodiment, the second bearing set, in a mid-body CAS provides the agility of a four canard system by incorporating elements of the standard approach. In one embodiment, the two bearing sets, a mechanical brake between the front of the projectile and the CAS, and a rotational measurement method between the CAS and the front of the projectile is used. In some cases, an inertial measurement unit (IMU) is installed to maintain attitude of the front of the projectile for target aim point. The CAS in some cases needs roll attitude relative to a vertical reference in order to execute the proper directional lift command that is maintained by the IMU. In some cases, the angle measurement between the CAS and the seeker on the front of the projectile provides that roll attitude transfer. The angle can be measured with an angle measurement unit, for example but not limited to a magnetometer, an accelerometer, or a gyroscope. The mechanical brake provides the ability to couple both the CAS and the front of the projectile together to perform a roll correction during the flight to maintain a vertical attitude.
- In certain embodiments, when utilizing a GPS guidance, the ability to point the antenna skyward offers better performance of the GPS subsystem. In addition, if the seeker is limited in its frame of view, front of the projectile can be moved back and forth and function as a poor man's scanner to increase the field of regard (FOR) by two to ten times. Oscillator motion can be generated by the coupling and decoupling of the CAS from the front of the projectile.
-
FIG. 4 depicts a diagrammatic view of one embodiment of a low inertia, rolling control actuation system with two bearing sets for a projectile according to the principles of the present disclosure. More specifically, aCAS 400 having only twocanards first bearing 402 decouples theCAS 400 from the front of the projectile 404 in the direction of flight. In one embodiment, the front of the projectile 404 comprises a warhead, fuze and/or a seeker. A second bearing set 406 decouples theCAS 400 from the rear of the projectile 408 in the direction of flight. In one embodiment, the rear of the projectile 408 comprises a rocket booster. - In certain embodiments, an onboard processor receives location information and/or fire control information and utilizes that to drive the CAS to maintain a proper trajectory to successfully arrive at the target. The positional data received for the weapons, asset, and/or the target's position can be processed to generate the navigation and auto pilot commands needed to execute the mission.
-
FIG. 5 depicts aflowchart 500 of one embodiment of a method or process according to the principles of the present disclosure. More specifically, a projectile with a low inertia, rolling control actuation system is provided 502. In one embodiment, the projectile has a front portion, a rear portion and has a control actuation system, which is located between the front portion and the rear portion of the projectile. In one embodiment the control actuation system has only two canards, and there is at least one bearing set being located between the control actuation system and the front portion, the rear portion, or both to decouple the control actuation system from the inertia of the front portion, the rear portion, or both the front portion and the rear portion of the projectile. In one embodiment, there is only one motor in the CAS, and in another, there is at least one motor per canard. - The
method 500 further includes decupling the control actuation system from the inertia of the front portion, the rear portion, or both the front and rear portion of the projectile via the at least one bearing set 504. One or more angle differentials are detected between the control actuation system and the front portion, the rear portion, or both the front and rear portion of the projectile via an angle-measuringdevice 506. The control actuation system moves in a radial direction using the control actuation system in a roll maneuver to set up for a course correction for the projectile by counter rotating the two canards of the control actuation system relative to the front, the rear, or both the front and the rear portion via the at least one bearing set and/or the motor and/or thebrake 508. Positive lift or negative lift is then applied to the control actuation system via the motor and/or the brake to complete a course correction of the projectile 510. - The computer readable medium as described herein can be a data storage device, or unit such as a magnetic disk, magneto-optical disk, an optical disk, or a flash drive. Further, it will be appreciated that the term “memory” herein is intended to include various types of suitable data storage media, whether permanent or temporary, such as transitory electronic memories, non-transitory computer-readable medium and/or computer-writable medium.
- It will be appreciated from the above that the invention may be implemented as computer software, which may be supplied on a storage medium or via a transmission medium such as a local-area network or a wide-area network, such as the Internet. It is to be further understood that, because some of the constituent system components and method steps depicted in the accompanying figures can be implemented in software, the actual connections between the systems components (or the process steps) may differ depending upon the manner in which the present invention is programmed Given the teachings of the present invention provided herein, one of ordinary skill in the related art will be able to contemplate these and similar implementations or configurations of the present invention.
- It is to be understood that the present invention can be implemented in various forms of hardware, software, firmware, special purpose processes, or a combination thereof. In one embodiment, the present invention can be implemented in software as an application program tangible embodied on a computer readable program storage device. The application program can be uploaded to, and executed by, a machine comprising any suitable architecture.
- While various embodiments of the present invention have been described in detail, it is apparent that various modifications and alterations of those embodiments will occur to and be readily apparent to those skilled in the art. However, it is to be expressly understood that such modifications and alterations are within the scope and spirit of the present invention, as set forth in the appended claims. Further, the invention(s) described herein is capable of other embodiments and of being practiced or of being carried out in various other related ways. In addition, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of “including,” “comprising,” or “having,” and variations thereof herein, is meant to encompass the items listed thereafter and equivalents thereof as well as additional items while only the terms “consisting of” and “consisting only of” are to be construed in a limitative sense.
- The foregoing description of the embodiments of the present disclosure has been presented for the purposes of illustration and description. It is not intended to be exhaustive or to limit the present disclosure to the precise form disclosed. Many modifications and variations are possible in light of this disclosure. It is intended that the scope of the present disclosure be limited not by this detailed description, but rather by the claims appended hereto.
- A number of implementations have been described. Nevertheless, it will be understood that various modifications may be made without departing from the scope of the disclosure. Although operations are depicted in the drawings in a particular order, this should not be understood as requiring that such operations be performed in the particular order shown or in sequential order, or that all illustrated operations be performed, to achieve desirable results.
- While the principles of the disclosure have been described herein, it is to be understood by those skilled in the art that this description is made only by way of example and not as a limitation as to the scope of the disclosure. Other embodiments are contemplated within the scope of the present disclosure in addition to the exemplary embodiments shown and described herein. Modifications and substitutions by one of ordinary skill in the art are considered to be within the scope of the present disclosure.
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US17/269,157 US20220120544A1 (en) | 2018-10-04 | 2019-10-03 | Low inertia rolling control actuation system |
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