Patent Grant
11946727
A vertical launching system (VLS) is a launching system where a projectile, such as a missile or a rocket (referred to herein collectively as “projectiles”), is stored in a cell (also referred to as a “canister”) and launched in an upward (substantially vertical) direction. Once in the air, the projectile trajectory is shaped to fly in a desired direction, e.g., in the direction of a designated target.
A vertical launching system has various advantages, one related to the ability to fire a projectile in any desired direction by shaping the projectile's trajectory after it is ejected from its cell. Another advantage is related to the fact that projectiles are stored in cells which can be placed underground (or below deck in a ship or vehicle), and thus accommodate less area above ground (or on deck), and are also more protected from being damaged.
The presently disclosed subject matter includes a launching system and method that enable deflection of a missile during launch in a desired deflection angle, and which do not suffer from various shortcomings of known systems.
The disclosed system and method are applicable for trajectory shaping (or bending), not only for VLS applications, but also for shaping of a projectile trajectory sideways, in the horizontal plane rather than the vertical plane. For example, such capability is beneficial for quick hitting of time critical targets (TCT) by Multiple Launch Rocket Systems (MLRS). Horizontal trajectory shaping can help to save critical time, which is otherwise needed for turning the launcher toward the target in MLRS.
The presently disclosed subject matter includes a system and a method for launching a projectile (e.g., a statically stable projectile) towards a target, wherein the system comprises a control circuitry, a booster engine, and one or more thrusters adapted to be connected to the projectile and capable of being spun during launch around a longitudinal axis of the projectile, the control circuitry being operatively connected to the one or more thrusters;
The disclosed subject matter further includes the following aspects:
According to one aspect of the presently disclosed subject matter there is provided a system for launching a projectile towards a target, the system comprising:
In addition to the above features, the system according to this aspect of the presently disclosed subject matter can optionally comprise one or more of features (i) to (xxv) below, in any desired combination or permutation:
According to another aspect of the presently disclosed subject matter there is provided a method of launching a projectile towards a target, the method comprising:
According to yet another aspect of the presently disclosed subject matter there is provided a projectile comprising a control circuitry, a booster engine, and one or more thrusters adapted to be connected to the projectile and capable of being spun during launch around a longitudinal axis of the projectile, the control circuitry being operatively connected to the one or more thrusters;
The method and projectile in accordance with the presently disclosed subject matter can optionally comprise one or more of features (i) to (xxv) listed above with respect to the system in any technically possible combination or permutation.
In order to understand the presently disclosed subject matter and to see how it may be carried out in practice, the subject matter will now be described, by way of non-limiting examples only, with reference to the accompanying drawings, in which:
Unless specifically stated otherwise, as apparent from the following discussions, it is appreciated that throughout the specification discussions utilizing terms such as “calculating”, “determining”, “activating”, or the like, include action and/or processes of a computer that manipulate and/or transform data into other data, said data represented as physical quantities, e.g., such as electronic quantities, and/or said data representing physical objects.
The terms “system”, “sub-system” or variations thereof should be expansively construed to include any kind of hardware electronic device with a processing circuitry, which includes (at least one) computer processing device configured and operable to execute computer instructions stored, for example, on a computer memory being operatively connected thereto. Examples of such a device include, but are not limited to: a digital signal processor (DSP), a microcontroller, a microprocessor, a field programmable gate array (FPGA), an application specific integrated circuit (ASIC), or any other electronic computing device, and/or any combination thereof.
As used herein, phrases such as “for example,” “such as”, “for instance” and variants thereof may be used to describe non-limiting embodiments of the presently disclosed subject matter. Reference in the specification to “one case”, “some cases”, “other cases”, or variants thereof, means that a particular feature, structure, or characteristic, described in connection with the embodiment(s), is included in at least one embodiment of the presently disclosed subject matter. Thus, the appearance of the phrase “one case”, “some cases”, “other cases”, or variants thereof, does not necessarily refer to the same embodiment(s).
It is appreciated that certain features of the presently disclosed subject matter, which are, for clarity, described in the context of separate embodiments, may also be provided in combination in a single embodiment. Conversely, various features of the presently disclosed subject matter, which are, for brevity, described in the context of a single embodiment, may also be provided separately or in any suitable sub-combination.
For the sake of clarity, the term “substantially” may be used herein to imply the possibility of variations in values with an acceptable range, as would be apparent to a person skilled in the art. According to one example, the term “substantially” should be interpreted to imply possible variation of up to 10% over or under any specified value. According to another example, the term “substantially” should be interpreted to imply possible variation of up to 5% over or under any specified value. According to yet another example, the term “substantially” should be interpreted to imply possible variation of up to 2.5% over or under any specified value. According to a further example, the term “substantially” should be interpreted to imply possible variation of up to 1% over or under any specified value. For example, substantially vertical, may imply the possibility of some deviation from an exact 900 angle.
In embodiments of the presently disclosed subject matter, fewer, more, and/or different stages than those shown in
Bearing the above in mind, attention is now drawn to
The presently disclosed subject matter further includes, according to some examples, a projectile launching sub-system 140 configured for launching a projectile from a launching cell (otherwise known as “canister”). The launching sub-system is configured to eject the projectile from its cell (e.g., in a substantially vertical direction in VLS applications) and, following ejection, to bend (or deflect or shape) its trajectory so that the projectile points in a desired direction. Once the projectile is pointing in the desired direction, the projectile accelerates and is guided towards its target.
According to examples of the presently disclosed subject matter, launching of the projectile is performed using a three-phase thrust (booster) engine, designed to burn in three consecutive burning phases. Following activation and engine burn-out, the three burning phase engine can in some cases be separated from the front section in a multiple stage projectile configuration, or continue to fly with the front section in unified projectile configuration. The three-phases engine is designed to burn propellant stowed in the combustion chamber in a sequence of three distinct burning phases. During a short time period of the first burning phase, high pressure (e.g., 80 to 120 bar) is generated in the combustion chamber which generates, in turn, high thrust that provides the projectile with high acceleration for achieving a sufficient velocity during ejection out of the cell. During a time period of the second burning phase, lower pressure (e.g., 20 to 30 bar) and accordingly lower thrust, is generated for sufficient time needed for deflecting of the projectile velocity vector in a desired direction. According to one example, the total thrust of the second burning phase is at least two times lower than the thrust of a first burning phase. According to one example, the total thrust of the first burning phase and the second burning phase causes the projectile to accelerate to a maximal velocity which does not exceed 0.4 Mach. During the third burning phase, after the velocity vector of the projectile has been turned and the projectile is pointing in a desired direction, the engine generates high pressure (e.g., 80 to 120 bar) and accordingly high thrust, suitable for propelling the projectile in the desired direction towards the target.
A three-phase burning profile as suggested above can be obtained in a number of ways. One way of achieving this is by designing the propellant's shape in a manner that the propellant burns differently at different time periods, thus obtaining different burning phases, each phase adapted to provide the desired thrust for a desired time period. According to some examples, the propellant designated for the first phase is designed to have a complex geometrical shape (e.g., some type of complex polyhedron) that provides a greater relative surface area to thereby increase the amount of propellant that is burnt, notwithstanding its smaller volume. The thrust and time period of the first phase is adapted for ejecting the projectile from its cell. A second part of the propellant is designed to have a smoother surface with a smaller surface area relative to the surface of area of the propellant of the first phase. Thus, following consumption of the first part of the propellant, the second part is ignited and burnt, and, due to its smoother geometry, the thrust generated during the second phase is reduced relative to the first phase. The second part of the propellant is designed to burn during a second time period and provide thrust that is suitable for allowing deflection the projectile in a desired direction. A third burning phase follows, where burning of the propellant advances towards the perimeter of the burning chamber, allowing greater amounts of propellant to burn and resulting in an increase in the generated thrust. The propellant is designed such that the engine generates acceleration, providing sufficient velocity for driving the projectile towards a target.
An alternative option for achieving a three-phase burning profile may be based on design of a propellant grain with a different chemical formulation for each phase (e.g., a slow burning rate chemical for the low level of thrust of the second phase). The different chemical can be arranged in the combustion chamber so a first type of propellant is burnt during the first phase, a second type of propellant is burnt during the second phase, and a third type of propellant is burnt during the third phase, each propellant providing the required thrust for the respective phase.
As known in the art, the burn-out velocity (and, as a result, a maximal flight distance) depends on various parameters, including the shape and weight of the projectile, the amount of propellant designated for the third burning phase, efficiency of the propellant (Isp), efficiency of the engine nozzle etc. Such parameters can be taken into consideration for the engine design as known in the art.
In general, activation of a thruster 105 creates thrust transversal to the projectile's longitudinal axis, thus loading a moment that causes the projectile to turn around its center of inertia. This moment acts for a relatively short period of time during which the moment generates angular acceleration of the projectile, and, following burn-out of the thruster 105, the projectile gains an initial angular velocity of projectile body (also referred to herein as body angle rate) resulting in a change in the projectile attitude. A thrust vector of the projectile engine follows the projectile attitude and accelerates the projectile in a direction different from the direction of ejection. During this dynamic process, a velocity vector of a projectile turns correspondingly. Notably, the angular rate of the velocity vector turns more slowly as compared to the projectile body, giving rise to an angle of attack (an angle between the projectile body and its velocity vector), and consequently this angle creates a moment of aerodynamic forces loaded on the projectile. In case of a statically stable projectile, this moment, generated by the aerodynamic forces, slows down the initial angular rate of the projectile that was created by activating of thruster 105.
As known in the art, the term “statically stable” refers to a body where center of gravity (Xcg) is maintained at a forward position relative to the center of pressure (Xcp). Generally, the location of Xcg moves forward, toward the head of the projectile, during the boost phase of the projectile, due to propellant burning and a location of center of pressure (Xcp), and depends on projectile velocity and angle of attack. The term statically stable is used herein to include a projectile that is designed to be stable for all spans of velocities and angles of attack occurring during the trajectory shaping. At later stages of the projectile flight, the aerodynamic moment increases along with the increasing velocity of the projectile, which leads to stabilization of the projectile, or in other words to alignment of the projectile body with its shaped velocity vector. As further explained below, by controllably activating at least one thruster fixed to the projectile's body, a desired trajectory can be achieved, directing the projectile to a designated target.
At block 301 launching is initiated and the projectile is ejected from its cell. According to some examples, launching control circuitry 210 is configured, responsive to launching command, to ignite the multi-phase engine 220 (e.g., by activating igniter 226) and initiate launch. Information indicative of the direction and range to a target, and/or information indicative of a desired azimuth and inclination angles, can be provided to a projectile, for example as part of the mission data in launching command.
In response to the ignition, a first burning phase of the engine 220 is initiated. As mentioned above, during this phase a part of the propellant is burnt in the combustion chamber that creates a high level of thrust suitable for ejecting the projectile out of its canister. A sufficiently high ejection velocity is required in order to enable ejection and to reduce sensitivity of the projectile to ambient conditions such as winds. In order to avoid deflections of the projectile trajectory by wind, the ejection velocity generally significantly exceeds current wind velocity. An example of a common ejecting velocity value is between 30-40 meters per second. The time period of the first burning phase (Ti) is selected to allow the projectile to develop sufficient velocity to enable safe exit from the canister. In some examples (e.g., for thrust profile shown in
As mentioned above in some examples, the projectile is ejected out of the cell in a substantially vertical position (pointing upwards). In other examples the projectile is ejected in an inclined position. This is the case for example in MLRS, where deflection as disclosed herein can be executed sideways, in a horizontal direction relative to a projectile's launch direction.
According to some examples of the presently disclosed subject matter, the projectile is ejected out of its cell in a manner that causes it to spin around its longitudinal axis, causing, in turn, one or more thrusters 105 to spin. In some examples, canister 50 induces a spin rate to the projectile. An example of a spinning mechanism that can be optionally used during ejection of the projectile out of its canister in order to create spinning momentum around its longitude axis is described with reference to
Similarly, a thrusters-belt 150, connected to the projectile (e.g., using bearings to enable its spinning separately from the projectile body) can be spun by a spinning mechanism as described above with reference to
At block 303 in
As further explained below, according to some examples, during the second burning phase, launching control circuitry 210 is configured to control the activation timing of one or more deflection thrusters 105 according to a desired deflection azimuth and deflection angle.
The term “body deflection angle” is used herein to refer to the angle in which the projectile body is turned. Notably, the body deflection angle can be in the pitch direction and/or in the yaw direction, or in some combination of pitch and yaw directions, which can be controlled according to the activation timing of the thruster.
The term “velocity deflection angle” is used herein to refer to the angle in which the velocity vector of the projectiles is turned. Notably, the velocity deflection angle can be in any direction relative to projectile's launching direction, e.g., in azimuth and in elevation.
The term “deflection azimuth” is used herein to refer to the desired azimuth of deflection of the projectile's velocity vector, directing the projectile towards a desired direction, e.g., of a designated target.
The term “thruster activation azimuth” is used herein to refer to the azimuth of a thruster at the time of activation.
The term “thrust azimuth” is used herein to refer to the azimuth of an averaged thrust vector generated by one or more deflection thrusters. In general, it is desired that the deflection azimuth and thrust azimuth coincide. The thruster produces the thrust during its burning duration, and due to the spin of the thruster its thrust azimuth changes continuously. As explained in more detail below, the thruster activation time (which defines the thruster activation azimuth) is selected, such that the thrust azimuth and the deflection azimuth coincide as much as possible.
The time period of the second burning phase (Tii) can be selected according to the time needed for deflection of the projectile's velocity vector in a desired deflection angle. According to some examples, the duration of a second burning phase may be between 5 to 6 times longer relative to the first burning phase (e.g., as shown in
Following deflection of the projectile velocity vector during the second burning phase and upon burn-out of thruster(s) 105, the engine continues to produce thrust aligned with the projectile body attitude, resulting in the bending of the projectile trajectory, followed by entry to a third burning phase (block 305). During this phase, the third part of the propellant is burnt, generating thrust that is sufficient for accelerating and propelling the projectile towards a designated target. The time period of the third burning phase (Tiii) can be selected according to the time needed for acceleration of the projectile to designated burn-out velocity. During this phase the projectile aligns its body deflection angles with the velocity deflection angles.
Proceeding to
An initial activation timing of a first deflection thruster 105 is determined and an activation profile is selected (blocks 401, 403). The activation can include a sequence of relative activation timings of thrusters, additional to the first thruster, if such are available.
In general, calculation of initial activation timing and selection of an activation profile can be done based on information including mission data (including direction and range to target), nominal booster engine thrust profile, nominal spin rate of thruster, etc.
As mentioned above, an activation timing that enables to generate a thrust azimuth of thruster(s) 105 that coincides with the deflection azimuth is desired. Two factors related to the initial activation timing include the desired deflection azimuth and the deflection rate of the projectile's velocity angle, where the former prescribes the activation azimuth, and the latter prescribes the activating spin-cycle.
Calculations of activation timing can be executed onboard the projectile (by onboard processor 222), or can be otherwise executed at some other location by an off-board processing circuitry external to the projectile (e.g., ground control circuitry) and provided to a projectile e.g., as part of a mission data and stored for example in data repository 224 prior to the launch.
The initial activation timing (time of the first activation of any thruster 105) can be calculated based on the nominal spinning rate of the thruster (e.g., or the projectile, in case the entire projectile is spinning) and the initial angular position (azimuth) of the thruster before launch (e.g., stored in a data repository 224). Alternatively, if the actual spinning rate of the thruster (e.g., projectile) is known (e.g., measured by navigation sub-system 110 or launching sub-system 140 in real-time) the accuracy of calculation can be improved by taking into account real-time measured angle of the thruster. Various methods can be applied for measurement of thruster angular position.
According to one example, launching sub-system 140 comprises or is otherwise operatively connected to a gyroscope (e.g., as part of navigation instrumentations 230, which, in some examples, can be operatively connected to navigation sub-system 110 where IMU is installed) that integrates spinning rate and provides the actual (real-time) azimuth of thruster 105. Based on this information, control circuitry 210 can calculate (e.g., using processor 222) a more precise activation timing of thruster 105 in order to deflect the projectile in the desired direction.
Other methods of calculating spinning rate do not rely on a gyroscope. One such method makes use of the spinning mechanism described above with reference to
v2=v2*tan d
The spinning rate ω of the projectile is expressed by equation 2:
ωr=v2
The spinning rate can thus be calculated by equation 3:
ω>=(v1*tan d)/r
Once the spinning rate is known, the azimuth of thruster 105 can be calculated based on its initial angular position, the spinning rate, and timing.
In case a thrusters-belt 150 is spun instead of the entire projectile, in addition to gyros, the angular position of a thruster(s) relative to a projectile can be measured using any one of encoders, Hall-effect sensors, or any other known instrumentation for angle/angle rate measurements (together with the attitude of the projectile determined for example by the navigation system).
As mentioned above, activation timing is determined such that the thrusters thrust azimuth coincides with the desired deflection azimuth.
As mentioned above, the activation timing is also dependent on the specific burning profile of the thruster.
Reverting to the selection of an activation profile in
According to some examples, launching sub-system 140 comprises, or is otherwise operatively connected, to thruster(s) activation profiles database. For example, an activation profile database can be stored in a computer data repository 224 that is accessible to control circuitry 210. To this end data repository 224 can include for example a NAND memory device comprised in, or operatively connected to, control circuitry 210. The activation database can be implemented for example as a lookup table of some sort (“deflection lookup table”).
In some examples, the activation profile database maps each of a plurality of activation profiles to respective velocity deflection angles and/or range to a target. Thus, given the range to the target, the desired azimuth and elevation and velocity deflection angles can be calculated (onboard the projectile, or otherwise received prior to launch as part of the mission data). Based on this data, a suitable thruster(s) activation profile for deflecting the velocity vector of the projectile at a suitable angle is retrieved from the database. For example, launching control circuitry 210 can be configured, responsive to a launching command, to retrieve from the command the range to the target and retrieve from the database data indicative of an appropriate activation profile for deflecting the projectile to reach the target. The activation database is adapted to each type of projectile (e.g., missile) as the activation profile of the thruster is dependent on the specifics of the projectile, including its mass and lever arm, as further discussed below. An activation profiles database (e.g., formatted as a lookup table) can be generated based on simulation of a projectile flight including its thruster(s) activation, as is well known in the art.
As explained above, in some examples the projectile is ejected out of its cell while spinning around its longitudinal axis, while in other examples, only the thrusters-belt 150 attached to the projectile is spun around the longitudinal axis, while the projectile itself remains unspun. During the second burning phase, in each cycle (referred to herein as “activation spin-cycle” or simply “spin-cycle”) the thrusters complete a full spin around the longitudinal axis of the projectile. During each cycle, a certain thruster is located at a certain moment at an activation azimuth that would generate thrust matching a certain deflection azimuth. Activation of a thruster at an earlier spin-cycle provides a longer period of time for deflecting the projectile's trajectory as compared to a later spin-cycle, and thus affects the resulting deflection angle. Activation of the thruster or combination of thrusters 105 at the same thruster activation azimuth, but at different spin-cycles, results in deflection of a projectile trajectory to the same azimuth, but at different trajectory deflection angles.
Assuming for example, a spin rate of 5 Hertz, where a full spin (cycle) occurs over a time period of 200 milliseconds. In case the second burning phase is 2 seconds long, this provides, for each thruster, about 10 possible spin-cycles suitable for thruster activation for generating thrust in the same thrust azimuth. Notably, the number of possible thruster activations in a desired azimuth is increased where more thrusters are installed in the thruster-belt 150. For example, in case a pair of thrusters are installed in the thrusters-belt 150, the number of possible thruster activations in the desired azimuth increases to 20 (each half period of the spin-cycle).
In some examples, each activation profile indicates the activation spin-cycle assigned to each thruster (possibly some thrusters may not be activated at all, e.g., would be assigned with a null spin-cycle). In case more than one thruster is available, the activation profile indicates, for a respective combination of thrusters, an activation sequence of the thrusters and the respective activation spin-cycle assigned to each thruster in the sequence.
Each activation profile specifies the activation timing for each thruster in a group containing one or more thrusters, where the activation timing is selected, as discussed above, according to a desired deflection azimuth and also according to the desired deflection rate of the velocity vector. An activation timing of one or more thrusters is synchronized to a specific spin-cycle in order to achieve a desired deflection rate for different periods of time.
Thus, in some examples, assuming only one thruster is available, a suitable activation profile is selected indicating a certain spin-cycle, according to a desired deflection angle of the velocity vector, and the activation timing of the thruster is calculated according to the desired deflection azimuth and thrust profile of the thruster 105. This is also true when a plurality of thrusters are activated together. In case more than one thruster is activated sequentially, the activation profile includes, in some examples, the activation timing of the thrusters other than the first (which is the product of the activation timing calculation as explained above) which can be defined relative to the timing of the first thruster activation (initial activation). For example, an activation profile can include the spin-cycle assigned for activating each of the thrusters following the first thruster.
In case where a plurality of thrusters are fixed to the projectile around its circumference (“thrusters-belt”), different combinations of thrusters from the plurality of thrusters can be activated together or sequentially. Each such combination provides different deflection rate values of the projectile body and its velocity vector, due to the combination of thrusting vectors of simultaneously activated thrusters. Thus, by selecting a specific combination of thrusters, it is possible to more accurately control the moments acting on the projectile body for creating the projectile body deflection rate, and, accordingly, more accurately controlling the deflecting angles of the projectile trajectory.
For example, where only one thruster is available, the projectile body deflection rate is dependent on the thrust generated by that thruster alone (along with the thruster level arm and the projectile moment of inertia). When two thrusters are fixed to the thruster-belt 150 as shown in item b in
Effective deflection of the projectile trajectory occurs primarily from the time of thruster activation until the end of the second burning phase and beginning of the third burning phase, when the projectile accelerates and significant dynamic pressure is generated, thereby creating significant lift that opposes the deflection and stabilizes the deflection angle of the projectile trajectory.
As mentioned above, activation of a thruster at an earlier spin-cycle provides a longer period of time for deflecting the projectile trajectory as compared to a later spin-cycle. This is further demonstrated in
The bottom line in the graph shows about 50° deflection of the projectile's trajectory, from 90° at the launching to 40°, resulting from activation of two thrusters at the first spin-cycle during the second burning phase. The middle line shows about 40° deflection of the projectile trajectory from 90° at the launching to about 50°, resulting from activation of two thrusters at the second spin-cycle during the second burning phase. The top line shows about 30° deflection of projectile trajectory from 90° at the launching to 40°, resulting from activation of two thrusters at the third spin-cycle during the second burning phase. Accordingly, as shown, the same thruster can be activated at different spin-cycles, each spin-cycle prescribing a different deflection time period, resulting in deflection of projectile trajectory to different respective inclination angles. Thus, the resolution of activation profiles (representing a deflection angles grid) depends on the available activation combinations and the number of spin-cycles during the second burning phase.
Once a suitable activation profile has been determined, and the activation time (of the first thruster) has been calculated, one or more thrusters are activated in one or more activation spin-cycles. In response to activation of the thruster(s), the projectile trajectory is deflected at a desired deflection angle. Once the second burning phase is complete, the projectile trajectory assumes the desired deflection angle, and the third burning phase commences, where burning of the third part of the propellant generates thrust, providing acceleration for propelling the projectile in the direction of the target.
The following is an example of a calculation of the deflection angle which is a product of a certain activation profile.
Calculation of the initial pitch rate of a projectile:
Equation (4) for calculating the initial pitch rate upon thruster activation (assuming aerodynamic forces can be ignored at the beginning of the missile flight due to relatively low velocity, and gyroscopic effect is negligible due to low spin rate of the projectile):
For example, for:
L0=2, Ft=1000N, Iyy=100 kg*m2, and t0=50 milliseconds, the calculated pitch rate a is 1 radians per second.
As explained above, during trajectory shaping, different forces are applied onto the projectile. The following is an example of projectile kinematics calculation that takes into account these forces.
The following are a set of simplified equations for projectile velocity calculation during trajectory shaping (assuming aerodynamic damping forces and jet damping forces can be ignored).
Vz=V0+∫t
Vx=∫t
A trajectory angle (γ) is defined by following equation (7):
The angular position of the projectile body is defined by following equation (8):
An angle of attack of the projectile defined by the following equation 9:
α=θ−γ
These equations take into consideration variations in parameters during projectile shaping, including changes in mass, moment of inertia, and lever arm of the projectile, resulting in changes in mass distribution due to burning of the propellant.
The calculations described above can be used for determining the trajectory angle (γ) deflections provided by different thrusters activation profiles, and for generating a deflection lookup table to be used during missile launch, as described above.
The operations described with reference to
As explained above with reference to blocks 403 and 405 in
However, in some cases, the actual result of activation of one or more deflection thrusters 105 is different from that which was intended, resulting in a deviation from the desired deflection azimuth and/or deflection angle rate. Factors that may influence the projectile deflection include:
Accordingly, in order to achieve a more accurate deflection of the projectile, control system 100 (e.g., by navigation subsystem 110) of a projectile should track the real attitude of a projectile, and activate additional thrusters (e.g., second, third, fourth, etc.) in an updated timing that takes into account also the actually achieved deflection rate and deflection azimuth. According to some examples, launching control circuitry 210 is configured, following initial activation of the first thruster, to determine the effect of one or more previous activations of thrusters, as well as ambient conditions, on the projectile orientation. To this end, control circuitry can use information including real-time measurements (obtained, for example, from an onboard IMU) relating to the projectile state, including projectile spin rate, achieved (current) deflection azimuth, and deflection angle rate, as well as information on remaining thrusters available for activation, and their angular position (azimuth). Based on this information, control circuitry 210 can determine whether adaption of the activation profile is needed in order to rectify any deviation in the real-time orientation from the desired orientation.
In case a difference between the measured real-time orientation and the desired orientation of the projectile is detected, the thrusters' activation parameters of one or more thrusters is adapted in real-time in order to rectify this deviation. A selected activation profile can be updated, e.g., by changing the number of thrusters which are activated (adding or removing thrusters) and/or the activation time of different thrusters (e.g., changing the respective spin cycle of activation). For example, an additional one or more thrusters, previously not intended to be activated, can be activated for the purpose of deflecting the projectile in a direction opposite to the direction in which it excessively turned. In another example, the activation timing of a thruster can be adapted such that the thrust vector of thruster 105 is changed so it rectifies the deviation in the deflection azimuth. In yet a further example, in case of a deflection angle rate that is greater than a desired value, an intended activation of an additional thruster can be cancelled or otherwise delayed to a later activation spin-cycle, in order to reduce further increase in the deflection angle rate.
Thus, according to some examples, during the second burning phase, after the initial activation of the first thruster (block 4051), data related to the projectile state is continuously measured in real-time (block 4053) and compared to the desired state of the projectile. Specifically, real-time deflection azimuth and/or deflection angle rate are compared to desired deflection azimuth and deflection angle rate, to determine whether there exists any discrepancy between the observed (measured) and expected values (block 4055). Real-time deflection azimuth and deflection angle rate can be determined based on the initial azimuth of one or more thrusters (at the beginning of the second burning phase) and the angular and linear location and velocity which can be determined by an onboard Inertial Measurement Unit (IMU) which comprises accelerometers, and therefore provides more accurate results.
If a difference is found, processing circuitry 210 calculates, based on the difference and the available thrusters, an adaptation of the thrusters' activation sequence (updates the activation profile) that would rectify the deviation and provide the desired deflection azimuth and/or deflection angle rate (block 4057). Then, one or more thrusters are activated according to the calculation, for the purpose of rectifying the detected deviation in deflection azimuth and deflection angle rate (block 4059). This process can be repeated during trajectory shaping in a closed feedback loop in order to obtain more accurate results adapted to real-time conditions.
It is also to be understood that the presently disclosed subject matter is not limited in its application to the details set forth in the description contained herein or illustrated in the drawings. The presently disclosed subject matter is capable of other embodiments and of being practiced and carried out in various ways. Hence, it is to be understood that the phraseology and terminology employed herein are for the purpose of description and should not be regarded as limiting. As such, those skilled in the art will appreciate that the conception upon which this disclosure is based may readily be utilized as a basis for designing other structures, methods, and systems for carrying out the several purposes of the present presently disclosed subject matter.
| Number | Date | Country | Kind |
|---|---|---|---|
| 269920 | Oct 2019 | IL | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/IL2020/051087 | 10/8/2020 | WO |
| Publishing Document | Publishing Date | Country | Kind |
|---|---|---|---|
| WO2021/070185 | 4/15/2021 | WO | A |
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|---|---|---|
| 4401315 | Aug 1995 | DE |
| 102015009980 | Feb 2017 | DE |
| 1366334 | Jun 2006 | EP |
| 1439566 | Jun 1976 | GB |
| 2316663 | Mar 1998 | GB |
| 2316663 | Mar 1998 | GB |
| Entry |
|---|
| Machine Translation of DE-102015009980-A1, Graeser S, Feb. 2017 (Year: 2017). |
| Number | Date | Country | |
|---|---|---|---|
| 20220325993 A1 | Oct 2022 | US |
