High angle-of-attack missile control system for aerodynamically controlled missiles

Claim 2

A missile control system, which is stable at low and high angles-of-attack, having means for controlling roll tail deflection and means for controlling steering tail deflection and having roll sensors for providing roll signals and steering sensors for providing steering signals, respectively, the improvement comprising: feedback means for intentionally cross-coupling the roll signals into the steering tail deflection control means which compensate for steering changes due to induced roll at high angles of attack and for intentionally cross-coupling the steering signals into the roll tail deflection control means which compensate for roll changes due to induced steering at high angles of attack.

Claim 3

A missile control system, as in claim 1, wherein the feedback means comprises: a first gain element interposed between the roll sensor means and the steering tail deflection control means for providing gain to the roll signal which is cross-coupled into the steering tail deflection control means, and a second gain element interposed between the steering sensor means and the roll tail deflection control means for providing gain to the steering signal which is cross-coupled into the roll tail deflection control means.

Claim 4

A missile control system, as in claim 1, further comprising: means for switching the feedback means into the system at high angles-of-attack and out of the system at low angles-of-attack.

Claim 5

A missile control system, as in claim 3, wherein the steering signals provided by the steering sensors comprise: a yaw normal acceleration signal, a yaw angular acceleration signal, and a yaw angular rate signal, each steering signal having, in the first gain element, its own data-variable gain by which the corresponding steering signal is multiplied, and wherein the roll signals provided by the roll sensors comprise: a roll angular acceleration signal, a roll angular rate signal, and a roll angle signal, each roll signal having in the second gain element, its own data-variable gain by which the corresponding roll signal is multiplied.

Claim 6

A missile control system, as in claim 4, having steering control means for processing the steering signals to produce missile stabilizing steering tail deflection at low angles-of-attack and roll control means for processing the roll signals to produce missile stabilizing roll tail deflection at low angles-of-attack, the improvement further comprising: first summer means for receiving as inputs and combining the gained roll signals emanating from the first gain element, second summer means for combining the output of the first summer means with the processed steering signals from the steering control means, the output from the second summer means comprising the steering tail deflection rate signal, third summer means for receiving as inputs and combining the gained steering signals emanating from the second gain element, and fourth summer means for combining the output of the third summer means with the processed roll signals from the roll control means, the output from the fourth summer means comprising the roll tail deflection rate signal.

Claim 7

A missile control system, as in claim 4, having a guidance computer for generating data sets where each data set corresponds to a computed angle-of-attack together with a computed roll angle, the improvement comprising: a memory with locations which store gain values that are associated with the angle-of-attack and roll angle data sets, means for addressing a select plurality of locations for each data set, and means for outputting the contents of the locations, such that a plurality of respective gain values for a given data set, are read from the memory.

Claim 8

A missile control system as in claim 6, wherein the data sets generated by the guidance computer include dynamic pressure data together with angle-of-attack data and roll angle data.

Claim 9

A missile control system, as in claim 6, wherein each address comprises: a part which increments cyclically, and a part which corresponds to the data set; which remains unchanged while the other part increments; and which changes only in response to a change in the guidance computer data set.

Claim 10

A missile control system, as in claim 8, further comprising: a plurality of gated latch elements, each latch element being connected to the contents outputting means, to receive one of the gain value outputs and to hold the received gain value output, wherein the plurality of gain value outputs are outputted from the corresponding latch elements after the incrementing part of the address completes a cycle.

Claim 11

A missile control system, as in claim 9, further comprises: means for multiplying each steering signal by a corresponding gain value output and for multiplying each roll signal by a corresponding gain value output, such that the steering signals and the roll signals are appropriately gained in accordance with the given data set.

Claim 12

A missile control system, as in claim 10, wherein the steering signals and the roll signals are analog and the gain value outputs are digital, and the multiplying means comprises a multiplying digital-to-analog converter.

Claim 13

A missile control system, as in claim 9, further comprising: means for sequentially gating the latch elements in coordination with the incrementing of the address, such that each latch element is gated to hold the value of one distinct gain variable, wherein the corresponding gain value for each distinct gain variable is outputted by the memory at a particular time during the address incrementation cycle and entered into the corresponding latch element.

Claim 14

A missile control system as in claim 6 wherein the gain values for a given data set are determined by: defining a control input vector in terms of yaw tail deflection rate and roll tail deflection rate; defining a performance index, in accordance with a Model-in-the-Performance Index technique, as a function of the control input vector; and minimizing the performance index, determining altitude and Mach number of the missile, selecting a first set of flight equations which describe the motion of the missile as a result of body-originated aerodynamic effects in terms of altitude and Mach number and as a function of angle-of-attack, where the first set of flight equations comprises a plant matrix, selecting a second set of flight equations which describe the flight of the missile as a result of control surface effects wherein the second set of flight equations comprises a control matrix, defining a state vector and calculating a gain matrix such that the control input vector is the product of the gain matrix and the state vector, and extracting the variable gain values from the gain matrix corresponding to the given data set, such that the number of variables in the control input vector is not greater than the number of equations, in the gain matrix, which contain critical cross-coupling terms.

Claim 15

Apparatus for controlling the flight of an aerodynamically controlled missile, having inputs corresponding to sensed yaw angular rate, yaw normal acceleration, and roll angular rate said sensed inputs being processed through a plurality of signal shaping networks and low angle-of-attack gain constant elements and having a computed yaw input from a guidance computer corresponding to the desired yaw normal acceleration and a roll angle error input said computed yaw and roll angle error inputs being processed by low angle-of-attack gain constant elements, wherein the processed sensed yaw input is compared with the processed computed yaw input, providing a differential signal which is further processed and channelled as one input to a combiner element the output from which effects changes in tail surface deflection, and wherein the processed sensed roll angular rate input is added to the processed roll angle error input to produce a roll rate correction output, the improvement comprising: a summation element into which the roll rate correction output enters, a first gain changer, connected to receive as input the unprocessed sensed roll angular rate input, and switching means connecting the first gain changer as an input, corresponding to roll tail deflection rate, to the summation element when angle-of-attack and roll angle characteristics indicate that stability limits of the low angle-of-attack gain constant elements are exceeded, and, a second gain changer, connected to receive as input the further processed differential signal, and switching means connecting the second gain changer as an input to the summation element whenever the first gain changer is connected to the summation element, wherein the output of the summation element enters the combiner element, together with the further processed and channelled differential signal, to effect a proper tail surface deflection output.

Claim 16

Apparatus for controlling the flight of an aerodynamically controlled missile, having inputs corresponding to sensed yaw angular rate, yaw normal acceleration, and roll angular rate said sensed inputs being processed through a plurality of signal shaping networks and low angle-of-attack gain constant elements and having a computed yaw input from a guidance computer corresponding to the desired yaw normal acceleration and a roll angle error input said computed yaw and roll angle error inputs being processed by low angle-of-attack gain constant elements, wherein the processed sensed yaw input is compared with the processed computed yaw input, providing a differential signal which is further processed and channelled as one input to a combiner element the output from which effects changes in tail surface deflection, and wherein the processed sensed roll angular rate input is added to the processed roll angle error input to produce a roll rate correction output, the improvement comprising: a summation element into which the roll rate correction output enters, a first gain changer, connected to receive as input the unprocessed sensed roll angular rate input, and switching means connecting the first gain changer as an input, corresponding to roll tail deflection rate, to the summation element when angle-of-attack and roll angle characteristics indicate that stability limits of the low angle-of-attack gain constant elements are exceeded, and, a second gain changer, connected to receive as input the further processed differential signal, and switching means connecting the second gain changer as an input to the summation element whenever the first gain changer is connected to the summation element, wherein the output of the summation element enters the combiner element, together with the further processed and channelled differential signal, to effect a proper tail surface deflection output.

Claim 17

Apparatus, as in claim 14, wherein each sensed and computed yaw input has a complementary, orthogonal input associated therewith which undergoes processing identical to the respective sensed and computed yaw input processing, the improvement further comprising: a third gain changer, connected to receive the further processed differential signal resulting from the complementary, orthogonal inputs, and an intermediate combiner, interposed between the second gain changer and its respective switch means, which combines the outputs from the second changer and the third gain changer, the output from the intermediate combiner corresponding to the yaw tail deflection rate when stability limits of the low angle-of-attack gain constant elements are exceeded.

Claim 18

Apparatus, as in claim 14, wherein the first, second, and third gain changes comprise: means for multiplying the input to each gain changer by a corresponding gain, the value of which depends on the desired angle-of-attack and roll angle of the missile.

Claim 19

Apparatus, as in claim 16, further comprising: permanent read-only memory means in which the gain values of each gain changer are stored and from which specific gain values are read, wherein the input to the permanent read-only memory comprises angle-of-attack and roll angle values.

Claim 20

Apparatus, as in claim 17, wherein the input to the permanent read-only memory further comprises the value of dynamic pressure.