EP0714013A1 - Guidance loop for missile - Google Patents

Abstract

The steering loop uses a target tracking head with a limited field of view,k the sight line of the target tracking head defined by respective angles relative to the missile pitch and yaw axes. The signals from the target tracking head are fed to a signal processor, providing signals for the movement of the missile, fed to the steering controls for guiding the missile onto the target. The signal processor includes a circuit (32) which corrects the signals provided for steering the missile, to ensure that the line of sight remains with in the target tracking head field of view.

Description

The invention relates to a steering loop for missiles which are guided to a target by a seeker head, the seeker head having a limited field of vision, comprising a seeker head which determines the line of sight to a target by means of squint angles with respect to missile-fixed pitch and yaw axes and provides seeker head signals Signal processing means which are acted upon by the seeker head signals for generating signals determining the movement of the missile, and guidance means which are acted upon by these signals for guiding the missile to the target.

The seeker head usually contains an imaging optical system and a sensor. The imaging optical system has an optical axis. A control loop containing the sensor aligns the optical axis of the optical system with a target detected by the sensor. This optical axis then defines a "line of sight" to the target. The position of the line of sight relative to the missile can be defined by two "squint angles" around a yaw axis or a pitch axis. The optical system with the sensor forms a "viewfinder".

The search head provides search head signals. According to a steering law, steering signals are generated through which the missile is guided to the detected target. In the steering law of "proportional navigation", the steering signals are, for example, proportional to the rotational speed of the Line of sight in inertial space. The steering signals control the movement of control surfaces. In the case of proportional navigation, the steering tries to keep the position of the line of sight in the room constant. The control loop with the viewfinder as a measuring element and the control surfaces (or the like) as an actuator through which the missile is guided to the target is referred to as a "steering loop".

A transverse acceleration of the missile is to be achieved by the movement of the control surfaces. For this purpose, the missile changes its angle of attack, i.e. the angle between the airspeed vector and the longitudinal axis of the missile. This change in the angle of attack in turn changes the squint angle of the seeker head. The missile changes its position in space relative to the essentially fixed line of sight.

The optical beam path of the viewfinder runs through a window in the area of the tip of the missile. This window defines a field of view of the viewfinder. For aerodynamic and optical reasons, this window is often provided on the side of the tip of the missile. This limits the size of the permissible squint angle. If the line of sight to the target leaves the field of vision of the missile, the seeker loses the target.

Examples of missiles in which the windows are provided on the side at the tip of the missile are shown in US Pat. No. 4,717,822 and EP-OS 0 482 352.

The invention has for its object to design a steering loop for missiles of the type mentioned so that a loss of target is avoided by limiting the field of view of the viewfinder.

According to the invention, this object is achieved in that the signal processing means contain means for influencing the signals determining the movement of the missile, which ensure such movement of the missile that the line of sight is always kept in the area of the face of the seeker head.

According to the invention, the signals determining the movement of the missile, e.g. the steering signals, not only determined by the steering law in the sense of optimal guidance of the missile to the target but also influenced in that the line of sight remains safe in the field of view of the seeker head. So it may be an optimal steering signal in the sense of target tracking is limited and made less optimal if the line of sight corresponding to the optimal steering signal would move the line of sight out of the field of vision and a loss of target would occur. Optimal target tracking is of no use if the target is eventually lost and the missile becomes disoriented. The task of keeping the line of sight in the field of view of the seeker head can make a roll movement of the missile not required by the steering law necessary even when the window is asymmetrical.

Embodiments of the invention are the subject of the dependent claims.

Fig.1

ist eine schematisch-perspektivische Darstellung eines zielverfolgenden Flugkörpers mit einem Suchkopf dessen Strahlengang durch ein Fenster hindurchtritt, das seitlich im Bereich der Spitze des Flugkörpers angeordnet ist.

Fig.2

veranschaulicht das Gesichtsfeld des Suchers Suchkopfes von Fig.1 in bezug auf die Richtung der Längsachse des Flugkörpers.

Fig.3

ist ein Blockdiagramm und zeigt die Lenkschleife des Flugkörpers von Fig.1.

Fig.4

ist ein Blockdiagramm und zeigt die Mittel zur Beeinflssung der die Bewegung des Flugkörpers bestimmenden Signale, durch welche die Sichtlinie zum Ziel stets innerhalb des Gesichtsfeldes des Suchkopfes gehalten wird.

Fig.5

zeigt ein "Kommandofenster", welches die Regeln symbolisiert, nach denen in Abhängigkeit von den Schielwinkeln eine Rollbewegung des Flugkörpers eingeleitet wird.

Fig.6 und 7

veranschaulichen die Wirkung einer 180°-Rollbewegung des Flugkörpers auf die relative Lage von Sichtlinie und Gesichtsfeld.

Fig.8

veranschaulicht die Drehbewegung des Flugkörpers in dem Fall, daß die Sichlinie sich dem seitlichen Rand des Gesichtsfeldes nähert.

Fig.9

veranschaulicht die Drehbewegung des Flugkörpers für einen weiteren Typ der relativen Lage von prädizierter Sichtlinie und Längsachse des Flugkörpers.

An embodiment of the invention is explained below with reference to the accompanying drawings.

Fig. 1

is a schematic-perspective representation of a target-tracking missile with a seeker whose beam path through a window passes, which is arranged laterally in the area of the tip of the missile.

Fig. 2

Figure 1 illustrates the field of view of the seeker seeker head of Figure 1 with respect to the direction of the missile's longitudinal axis.

Fig. 3

Figure 3 is a block diagram showing the missile guidance loop of Figure 1.

Fig. 4

is a block diagram and shows the means for influencing the signals determining the movement of the missile, by means of which the line of sight to the target is always kept within the field of view of the seeker head.

Fig. 5

shows a "command window", which symbolizes the rules according to which a rolling movement of the missile is initiated depending on the squint angle.

Fig. 6 and 7

illustrate the effect of a 180 ° roll movement of the missile on the relative position of the line of sight and field of view.

Fig. 8

illustrates the rotational movement of the missile in the event that the line of sight approaches the lateral edge of the field of view.

Fig. 9

illustrates the rotational movement of the missile for another type of the relative position of the predicted line of sight and the longitudinal axis of the missile.

1 is a schematic perspective illustration of a missile 10 with engines 12 and 14, a seeker head 16 at the tip and control surfaces 18. The seeker head 16 has a window 20 with three facets. The (not visible) viewfinder "sees" through this window 20 with a line of sight 22. The direction of the longitudinal axis of the missile 10 is designated by x _b . The position of the line of sight 22 relative to the missile 10 is defined by two angles λ _yp and λ _zp around the missile-fixed pitch or yaw axis y _b or z _b .

2 shows the position of the field of view 24 of the seeker head 16 in relation to the direction of the longitudinal axis x _b . The field of view is limited around the pitch axis y _b by the maximum pitch squint angles ε _yo and -ε _yu . The field of view around the yaw axis z _b is limited by the maximum yaw squint angle -ε _z and + ε _z . The field of view 24 is highly asymmetrical about the pitch axis. The field of view 24 is symmetrically but naturally limited around the yaw axis.

Figure 3 illustrates the steering loop or steering control loop. A target is designated by 26. The seeker 28 detects the target 26. The viewfinder 28 adjusts itself to the target with its line of sight. The position of the line of sight 22 with the pitch and yaw squint angles can be tapped from the viewfinder 28, for example in the form of gimbal angles. The squint angles λ _ym and λ _zm measured in this way are, as indicated by a loop 30, applied to a circuit 32 which counteracts a loss of target.

In addition, steering is carried out by a steering computer 34 according to a steering law depending on the line of sight or its rotational speed. The steering computer 34 commands steering law lateral accelerations a _yco and a _zco , through which the missile 10 should track the target 26 according to the applied steering law. However, these steering law transverse accelerations a _yco and a _zco are still applied to the circuit 32 and, if necessary, modified so that a loss of target is counteracted or a rolling movement of the missile 10 is initiated. The circuit 32 also receives the measured lateral accelerations a _ym and a _{zm of} the missile 10. This is represented by the loop 36. The circuit 32 supplies commanded lateral accelerations a _yc and a _zc in the direction of the pitch or yaw axis. The circuit also provides commands ΔΦ _c , which initiate a rolling movement of the missile. The movement of the missile again affects the viewfinder 28. This is represented by the loop 38 and a summing point 40.

The circuit 32 is shown in detail in FIG.

At an input 42, the steering law lateral acceleration a _yco supplied by the steering computer 34 is _applied in the direction of the pitch axis. The steering law lateral acceleration a _zco supplied by the steering computer 34 is present at an input 44 in the direction of the yaw axis. The measured lateral acceleration a _{ym of} the missile 10 is present at an input 46 in the direction of the pitch axis. The measured lateral acceleration a _{zm of} the missile 10 is present at an input 48 in the direction of the yaw axis. The differences between the steering law transverse accelerations and the measured lateral accelerations are formed in summation points 50 and 52: $$\begin{array}{c}\begin{array}{c}{\text{Δa}}_{\text{y}}{\text{= a}}_{\text{yco}}{\text{- a}}_{\text{ym}}\\ {\text{Δa}}_{\text{e.g.}}{\text{= a}}_{\text{zco}}{\text{- a}}_{\text{zm}}\text{.}\end{array}\end{array}$$

These are the changes in the lateral accelerations that would result if the steering law lateral accelerations calculated by the steering computer 34 were generated. These changes would lead to changes in the angle of attack. Such changes in the angle of attack lead to opposite changes in the squint angle. The missile 10 is pivoted about the pitch and yaw axis relative to the substantially fixed line of sight. If, for example, the pitch angle of the missile 10 is changed clockwise relative to the inertial space and the line of sight 22 fixed therein in order to achieve a transverse acceleration acting in the direction of the yaw axis, then the squint angle changes, namely the angle at which the target is seen from the missile 10 , counterclockwise. A commanded change in the lateral acceleration corresponds to a change in the angle of attack resulting from the aerodynamics of the missile 10. This in turn causes a change in the squint angle in question. A change in the squint angle can therefore be predicted from a commanded change in the lateral acceleration. 4 it is assumed that the relationship between the commanded change in the lateral acceleration and the change in the associated squint angle predicted from this is the proportionality: $$\begin{array}{c}\begin{array}{c}{\text{Δλ}}_{\text{e.g.}}{\text{= -K}}_{\text{a}}{\text{Δa}}_{\text{y}}\\ {\text{Δλ}}_{\text{y}}{\text{= K}}_{\text{a}}{\text{Δa}}_{\text{e.g.}}\text{.}\end{array}\end{array}$$

The multiplication by the coefficients -K _a and K _a is shown in FIG. 4 by blocks 54 and 56, respectively. Instead of the linear relationship, there may also be more complex and non-linear relationships between the changes in the squint angle and the commanded changes in the lateral accelerations.

Predicted squint angles can now be formed from these changes in the squint angle as the sum of the current measured squint angle and the changes in the squint angle. The measured squint angles λ _ym and λ _zm are tapped at the viewfinder 28 (FIG. 3) and applied to the circuit 32 via loop 30. These measured squint angles λ _ym and λ _zm are applied to inputs 58 and 60 of circuit 32 (FIG. 4). The measured squint angles λ _ym and λ _zm are overlaid with the calculated changes in squint angles at summing points 62 and 64, respectively. This results in the predicted squint angles λ _yp and λ _zp .

The predicted squint angles λ _yp and λ _zp thus obtained are applied to limiters 66 and 68, respectively. The limiters limit the squint angle values to predetermined limit values ν _yo and -ν _yu or ν _z and -ν _z . The values of ν _yo and -ν _yu or ν _z and -ν _z are somewhat smaller than the values ε _yo and ε _yu or -ε _z and + ε _z mentioned above in connection with FIG. For safety reasons, the area defined by the delimiters 66 and 68 is somewhat reduced compared to the real field of view determined by the window 20.

The limiters 66 and 68 accordingly supply limited values of the predicted squint angles λ _yp and λ _zp if the predicted squint angles fall outside the field of view defined by the limiters 66 and 68. The measured squint angles are then subtracted from these limited squint angles in summing points 70 and 72, respectively. This is represented by the loops 74 and 76, respectively. This results in limited changes in the squint angle Δλ _yp Δλ _zp . These limited changes in squint angles now become one Operation that is inverse to the operation represented by blocks 56 and 54, respectively. In the present case, these inverse operations are multiplications by 1 / K _a or -1 / K _a . These inverse operations are represented in FIG. 4 by blocks 78 and 80, respectively. The inverse operation according to block 80 provides a modified change Δa _{yp in} the lateral acceleration in the direction of the pitch axis. The inverse operation according to block 78 provides a modified change Δa _{zp in} the lateral acceleration in the direction of the yaw axis. The corresponding measured transverse accelerations a _ym and a _{zm are} superimposed on these modified changes in summing points 82 and 84, respectively. This is shown in Figure 4 by loops 86 and 88, respectively.

As a result, first commanded accelerations a _yc1 and a _zc1 are obtained. These first commanded accelerations a _yc1 and a _zc1 are connected to further limiter means 90. There, if necessary, they experience a further limitation if the angle of attack commanded by a lateral acceleration becomes too large for aerodynamic reasons. Commanded accelerations a _yc and a _zc then appear at outputs 92 and 94. These control the control surfaces of the missile, as can be seen from FIG. 3.

In addition, the missile 10 can be given a rolling movement, by means of which the missile 10 is moved into a roll position in which the window 20 (FIG. 1) is favorable to the line of sight 22. The yaw squint angle λ _z should be small and the pitch squint angle λ _y should fall in the less restricted negative range (below in Fig. 2). For this purpose, the predicted squint angles λ _yp and λ _{zp are switched} to inputs 96 and 98 of a roll control 100.

The roll control 100 delivers a roll command ΔΦ _c at an output 102.

• (a) Wenn der prädizierte Gier-Schielwinkel λ_zp und der Nick-Schielwinkel λ_yp die Bedingung erfüllen: $${\text{- δ ≦ λ}}_{\text{zp}}\text{≦ δ}$$
  
  und $${\text{λ}}_{\text{yp}}{\text{≦ ν}}_{\text{yo}}\text{,}$$
  
  wobei δ und ν_yo die Begrenzungen eines .Fensters'' für die Sichtlinie in dem Gesichtsfeld 24 des Suchkopfes 16 ist, wird die Rollage des Flugkörpers 10 beibehalten.
• (b) Wenn die präzedierten Schielwinkel in einem Bereich $${\text{- δ ≦ λ}}_{\text{zp}}\text{≦ δ}$$
  
  und $${\text{λ}}_{\text{yp}}{\text{≧ ν}}_{\text{yo}}\text{,}$$
  
  liegen, wird dem Flugkörper 10 eine 180° Rolldrehung kommandiert.
• (c) Wenn die prädizierten Schielwinkel λ_zp und λ_yp in den Bereich $${\text{λ}}_{\text{zp}}{\text{≦ -δ; λ}}_{\text{yp}}{\text{≦ -ν}}_{\text{yo}}{\text{oder λ}}_{\text{zp}}{\text{≧ δ; λyp ≦ -ν}}_{\text{yo}}$$
  
  liegen, wird dem Flugkörper 10 eine Rollbewegung um den Winkel $${\text{ΔΦ}}_{\text{c}}{\text{= arctan (λ}}_{\text{zp}}{\text{/λ}}_{\text{yp}}\text{)}$$
  
  kommandiert.
• (d) Wenn die prädizierten Schielwinkel λ_zp und λ_yp in den Bereich $${\text{λ}}_{\text{zp}}{\text{≦ -δ; -ν}}_{\text{yo}}{\text{≧ λ}}_{\text{yp}}{\text{≦ ν}}_{\text{yo}}{\text{oder λ}}_{\text{zp}}{\text{≧ δ; -ν}}_{\text{yo}}{\text{≦ λ}}_{\text{yp}}{\text{≦ ν}}_{\text{yo}}$$
  
  liegen, wird dem Flugkörper im Fall eines positiv prädizierten Gier-Schielwinkels λ_zp eine Rolldrehung um den Winkel -90° und im Fall eines negativ prädizierten Gier-Schielwinkels λ_zp eine Rolldrehung um den Winkel + 90° kommandiert.

The roll command ΔΦ _c results from the predicted squint angles λ _yp and λ _zp according to predefined rules:

• (a) If the predicted yaw squint angle λ _zp and the pitch squint angle λ _{yp meet} the condition: $${\text{- δ ≦ λ}}_{\text{zp}}\text{≦ δ}$$
  
  and $${\text{λ}}_{\text{yp}}{\text{≦ ν}}_{\text{yo}}\text{,}$$
  
  where δ and ν _{yo are} the boundaries of a "window" for the line of sight in the field of view 24 of the seeker head 16, the rolling position of the missile 10 is maintained.
• (b) If the specified squint angle is in a range $${\text{- δ ≦ λ}}_{\text{zp}}\text{≦ δ}$$
  
  and $${\text{λ}}_{\text{yp}}{\text{≧ ν}}_{\text{yo}}\text{,}$$
  
  lie, the missile 10 is commanded a 180 ° roll rotation.
• (c) If the predicted squint angles λ _zp and λ _yp in the range $${\text{λ}}_{\text{zp}}{\text{≦ -δ; λ}}_{\text{yp}}{\text{≦ -ν}}_{\text{yo}}{\text{or λ}}_{\text{zp}}{\text{≧ δ; λyp ≦ -ν}}_{\text{yo}}$$
  
  lie, the missile 10 will roll around the angle $${\text{ΔΦ}}_{\text{c}}{\text{= arctan (λ}}_{\text{zp}}{\text{/ λ}}_{\text{yp}}\text{)}$$
  
  commanded.
• (d) If the predicted squint angles λ _zp and λ _yp in the range $${\text{λ}}_{\text{zp}}{\text{≦ -δ; -ν}}_{\text{yo}}{\text{≧ λ}}_{\text{yp}}{\text{≦ ν}}_{\text{yo}}{\text{or λ}}_{\text{zp}}{\text{≧ δ; -ν}}_{\text{yo}}{\text{≦ λ}}_{\text{yp}}{\text{≦ ν}}_{\text{yo}}$$
  
  lie, the missile is _commanded a roll rotation by the angle -90 ° in the case of a positive predicted yaw squint angle λ _{zp and} a roll rotation by the angle + 90 ° in the case of a negatively predicted yaw squint angle λ _zp .

This is shown in Fig. 5 in the form of a "command window". Predicted (predicted) yaw squint angles λ _{zp are} plotted in the horizontal direction in FIG. Predicted pitch squint angles λ _{yp are} plotted in the vertical direction in FIG. Each point in the area of Fig. 5 therefore corresponds to a line of sight defined by two squint angles.

5 shows the real visual field 24 defined by the window 20. Furthermore, the restricted visual field 104 arranged within the real visual field 24 is shown, which is characterized by the Limiter values ν _yo and -ν _yu or ν _z and -ν _{z of} the limiters 66 and 68 is fixed.

. Das ist die oben angegebene Regel "(a)".In a region 106 which extends in the "vertical" direction from ν _yo to the edge of the visual field and in the "horizontal" direction from -δ to + δ, there is no change in the roll position. The line of sight 22 is essentially optimal to the window 20. ${\text{ΔΦ}}_{\text{c}}\text{= 0}$

. This is the rule "(a)" given above.

A 180 ° roll movement of the missile 10 is commanded in an area 108 which also extends in the horizontal direction from −δ to + δ and in the vertical direction from ν _yo to the “upper” edge of the field of view. The effect of such a 180 ° roll movement on the relative position of the line of sight and field of view can be understood from the schematic representation of FIGS. 6 and 7. In Figure 6 it is assumed that the window 20 is facing downwards. The roll axis x _{b of} the missile 10 is horizontal. The line of sight 22 is inclined in a vertical plane with respect to the roll axis x _b and lies in the region 108 near the edge of the field of view 24. If the missile 10 with the window 20 is then rotated through 180 ° about the roll axis x _b , then the result is 7: The position of the line of sight 22 and the position of the roll axis x _b remain unchanged. The edges ε _yo and -ε _{yu of} the field of view 24 are mirrored on the roll axis x _b . In Fig. 5 this would correspond to a rotation of 180 ° around the intersection of the λ _yp and λ _{zp axes} . The line of sight is then in the geometrically more favorable angular range of the field of view 22. This corresponds to the rule “(b)” given above.

If the line of sight 22 of the seeker head 16 lies in one of the areas 110 or 112, that is to say laterally offset from the longitudinal center plane of the field of view by more than the angle δ, the missile 10 rotates about the roll axis x _b and thus rotates the Field of view by an angle ΔΦ that the predicted line of sight 22 comes to rest on this longitudinal median plane. 8 shows the relationship for the roll angle ΔΦ _c to be commanded for this purpose $${\text{ΔΦ}}_{\text{c}}{\text{= tan λ}}_{\text{zp}}{\text{/ λ}}_{\text{yp}}\text{.}$$

This is the rule "(c)" given above.

des gedrehten Gesichtsfeldes.If the predicted line of sight of the seeker head lies in one of the fields 114 or 116 of FIG. 5, which extend along the “λ _zp axis”, then the missile 10 _rotates by 90 ° about the roll axis x _b . Fields 114 and 116 determine sets of possible lines of sight that are not affected by the rotation of missile 10. By a rotation of 90 ° this "amounts of sight" no longer lie on either side of λ _zp axis but on both sides of 90 ° -to gedrehten- λ _yp axis and centrally in the field of view. In the case of the field 114 (λ _zp <0), the missile and thus the field of view 24 must _rotate clockwise, in the case of the field 116 (λ _zp > 0) counterclockwise. Then the predicted line of sight is in the area ${\text{0> λ}}_{\text{yp}}{\text{> -ε}}_{\text{yu}}$

of the rotated field of view.

ergibt. Durch eine solche Drehung des Flugkörpers 10 und damit des Gesichtsfeldes 24 kommt der eine Sichtlinie repräsentierende Punkt aus dem Feld 118 oder 120 auf die λ_yp-Achse zu liegen, allerdings in dem ungünstigen positiven Bereich (oben in Fig.5). Deshalb erfolgt zusätzlich eine weitere Drehung um 180°.If the predicted line of sight lies in one of the areas 118 or 120, then, as shown in FIG. 9, there is first a rotation by a roll angle ΔΦ _c , which results from the relationship ${\text{ΔΦ}}_{\text{c}}{\text{= arctan (λ}}_{\text{zp}}{\text{/ λ}}_{\text{yp}}\text{)}$

results. Such a rotation of the missile 10 and thus of the field of view 24 causes the point representing a line of sight from the field 118 or 120 to lie on the λ _yp axis, but in the unfavorable positive range (top in FIG. 5). Therefore, there is an additional 180 ° rotation.

In each of the roller positions commanded in this way, the limiters 66 and 68 ensure that the line of sight 22 is within the restricted field of view 104. The commanded rolling movements ensure that the limitation by the limiters 66 and 68 need not be too strong. The interaction of the rolling movements commanded by the roll control 100 and the limitation by the limiters 66 and 68 ensure that, on the one hand, no loss of target can occur, but on the other hand, the control takes place in the best possible way according to the steering law used.

However, each of the two measures could also be applied independently of the other.

Claims (9)

Guiding loop for missiles (10) which are guided to a target by a seeker head (16), the seeker head (16) having a limited field of view (24) (a) a seeker head (16), which determines the line of sight (22) to a target (26) by squint angle (λ _y , λ _z ) with respect to missile-fixed pitch and yaw axes (y _b , z _b ) and delivers seeker head signals, (b) signal processing means which are acted upon by the seeker head signals for generating signals (ΔΦ _c , a _yc , a _zc ) and which determine the movement of the missile (10) (c) guidance means which are acted upon by these signals for guiding the missile to the target, characterized in that (d) the signal processing means contain means (32) for influencing the signals (ΔΦ _c , a _yc , a _zc ) determining the movement of the missile (10), which ensure such movement of the missile (10) that the line of sight (22) is always held in the area of the face field (24) of the seeker head (16). Steering loop according to claim 1, characterized in that the signal processing means (a) have means (34) for generating signals (a _yco , a _zco ), which lateral steering accelerations of the missile (10) generate from the seeker head signals according to a steering law, (b) means (52,56,62; 50,54,64) for calculating predicted squint angles (λ _yp , λ _zp ) resulting from the steering law lateral accelerations, (c) means (66, 68) for limiting the predicted squint angles (λ _yp , λ _zp ) thus obtained to an area (104) within the field of view (24) of the seeker head (16), (d) Means (70,78,84; 72,80,82) for forming steering signals commanding lateral accelerations (a _yc1 , a _zc1 ) in accordance with the squint angles thus limited. Steering loop according to claim 2, characterized in that
contains the means for calculating predicted squint angles resulting from the steering law lateral accelerations: (a) means (62, 64) for forming the difference between the respective steering law lateral acceleration and a measured lateral acceleration, (b) means (56, 54) for predicting a squint angle change (Δλ _y , Δλ _z ) from this difference according to a predetermined, a model of the relationship between the function representing the transverse acceleration difference and the squint angle change, (c) means (62, 64) for forming the sum of the predicted squint angle change (Δλ _y , Δλ _z ) and the current squint angle (λ _ym , λ _zm ) as the predicted squint angle. Steering loop according to claim 3, characterized in that
the means for the formation of lateral accelerations commanding steering signals according to the limited squint angle include: (a) means ( ₇₀ , ₇₂ ) for forming the difference (Δλ _yp , Δλ _zp ) of the limited, predicted squint angle and the current squint angle, (b) means ( ₇₈ , 80) for forming a signal representing a change in acceleration (Δa _yp , Δa _zp ) as an inverse function of the function representing a model of the relationship between the transverse acceleration difference and the squint angle change, (c) means (84, 82) for superimposing this signal representing an acceleration change and the measured acceleration signal (a _ym , a _zm ) to form a steering signal. Steering loop according to claim 4, characterized in that the steering signals obtained are subjected to an additional limitation in accordance with an angle of attack of the missile. Steering loop according to one of claims 1 to 5, characterized in that the two predicted squint angles (λ _yp , λ _zp ) are applied to a roll control (100) by means of which a roll position of the missile (10) can be specified in which the line of sight ( 22) is favorable to the field of view (24) of the seeker head (16). Steering loop according to claim 6, characterized in that the roll control (100) can specify roll positions (ΔΦ _c ) of the missile (10) according to predetermined rules, depending on the value ranges in which the predicted squint angles (λ _yp , λ _zp ) lie. Steering loop according to claim 7, characterized in that the roll position of the missile (10) is determined by the roll control (100) according to the following rules: (a) If the predicted yaw squint angle λ _zp and the pitch squint angle λ _{yp meet} the condition: $${\text{- δ ≦ λ}}_{\text{zp}}\text{≦ δ}$$

and $${\text{λ}}_{\text{yp}}{\text{≦ ν}}_{\text{yo}}\text{,}$$

where δ and ν _{yo are} the boundaries of a "window" (106) for the line of sight (22) in the field of view (24) of the seeker head (16), the rolling position of the missile (10) is maintained. (b) If the specified squint angles (λ _yp , λ _zp ) are in a range $${\text{- δ ≦ λ}}_{\text{zp}}\text{≦ δ}$$

and $${\text{λ}}_{\text{yp}}{\text{≧ ν}}_{\text{yo}}\text{,}$$

lie, the missile (10) is commanded a 180 ° roll rotation. (c) If the predicted squint angles λ _zp and λ _yp in the range $${\text{λ}}_{\text{zp}}{\text{≦ -δ; λyp ≦ -ν}}_{\text{yo}}{\text{or λ}}_{\text{zp}}{\text{≧ δ; λyp ≦ -ν}}_{\text{yo}}$$

lie, the missile (10) will roll around the angle $${\text{ΔΦ}}_{\text{c}}{\text{= arctan (λ}}_{\text{zp}}{\text{/ λ}}_{\text{yp}}\text{)}$$

commanded. (d) If the predicted squint angles λ _zp and λ _yp in the range $${\text{λ}}_{\text{zp}}{\text{≦ -δ; -ν}}_{\text{yo}}{\text{≧ λ}}_{\text{yp}}{\text{≦ ν}}_{\text{yo}}{\text{or λ}}_{\text{zp}}{\text{≧ δ; -ν}}_{\text{yo}}{\text{≦ λ}}_{\text{yp}}{\text{≦ ν}}_{\text{yo}}$$

lie, the missile (10) in the case of a positive predicted yaw squint angle λ _zp a roll rotation by the angle -90 ° and in the case of a a predicted yaw squint angle λ _{zp commands} a roll rotation through the angle + 90 °. Steering loop according to claim 8, characterized in that the roll position of the missile (10) can also be determined by the roll control (100) according to the following rule:
If the predicted squint angle (λ _yp , λ _zp ) in one of the ranges $${\text{λ}}_{\text{yp}}{\text{> ν}}_{\text{yo}}{\text{and either λ}}_{\text{zp}}{\text{≦ -δ or λ}}_{\text{zp}}\text{≧ + δ,}$$

lie, then first a rotation by a roll angle ΔΦ, which results from the relationship ${\text{ΔΦ = arctan (λ}}_{\text{zp}}{\text{/ λ}}_{\text{yp}}\text{)}$

results and commands a further rotation of 180 °.

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