CN117985236B - Flight control method, device and control equipment based on fluid thrust vector - Google Patents
Flight control method, device and control equipment based on fluid thrust vector Download PDFInfo
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Abstract
The invention provides a flight control method, a device and control equipment based on a fluid thrust vector, and relates to the technical field of aircrafts, wherein the method comprises the following steps: acquiring current flight data of an aircraft and a current expected vector deflection angle of a fluid thrust vector; determining a current valve opening instruction based on current flight data, a current expected vector deflection angle and a preset feedforward controller based on vector deflection inverse model compensation; the vector deflection inverse model is established and updated based on historical flight data of the aircraft; and performing flight control of the fluid thrust vector on the aircraft based on the current valve opening instruction. Therefore, on one hand, hysteresis nonlinear inhibition of fluid thrust vector control is realized through feedforward control, and on the other hand, a vector deflection inverse model is established and continuously and iteratively updated through historical flight data, so that the control precision of the fluid thrust vector is improved, and the problem of stability reduction of a control system caused by insufficient model precision and hysteresis nonlinearity is solved.
Description
Technical Field
The invention relates to the technical field of aircrafts, in particular to a flight control method, a device and control equipment based on a fluid thrust vector.
Background
In general, control of the aircraft about pitch, roll and yaw axes is achieved by elevators, ailerons and rudders, respectively, and deflection of these control surfaces changes the geometric boundary conditions of the aircraft, causing substantial changes in the flow around the aircraft, thereby producing aerodynamic and aerodynamic moments required for flight control. With the development of technology, the requirements of low detectability, short-distance take-off and landing performance, maneuverability and agility are improved, and a brand new flight control concept, i.e. a flight control technology without a control surface, is proposed by researchers. The control method can adopt a fluid type flight control technology to realize the flight control without a control surface, and the technology can thoroughly cancel the flap, aileron, elevator and rudder on an aircraft, even the whole horizontal tail and vertical tail, and can release to the greatest extent so as to completely avoid various defects caused by the current movable control surface.
At present, the mode of realizing the control plane-free flight control by adopting the fluid type flight control technology comprises the following steps: the vector execution mechanism changes the static pressure of the nozzle wall through blowing by utilizing a fluid thrust vector technology, thereby changing the direction angle of tail jet flow (namely changing the jet flow direction of a tail nozzle of an engine), realizing thrust vectorization and realizing pitching control of the aircraft by utilizing the fluid thrust vector.
The mechanism of the vector actuator is relatively complex, the establishment of a model depends on a ground test, the relation between the valve opening and the vector deflection angle is measured under the condition of stable airflow, and certain difference exists between the valve opening and the vector deflection angle and actual flight, so that the accuracy of the model of the vector actuator is lower; wherein the valve opening is used to vary the static pressure of the nozzle wall and thus the vector angle. If the inaccurate model is directly applied to the control system of the aircraft without processing, the attitude stability of the aircraft in actual flight cannot be ensured. Meanwhile, hysteresis characteristics existing in the deflection process of the passive fluid thrust vector jet flow can reduce stability of a control system, oscillation and phase lag are generated, rapidity of the control system is affected, positioning accuracy of a vector execution mechanism is reduced, and control accuracy of the attitude of an aircraft is further affected.
Disclosure of Invention
The invention aims to provide a flight control method, a device and control equipment based on a fluid thrust vector, so as to solve the problem of stability reduction of a control system caused by insufficient model precision and hysteresis nonlinearity.
In a first aspect, an embodiment of the present invention provides a flight control method based on a fluid thrust vector, including:
Acquiring current flight data of an aircraft and a current expected vector deflection angle of a fluid thrust vector; the current flight data comprise current engine thrust, a last actual vector deflection angle at the last moment and a last actual valve opening;
Determining a current valve opening instruction based on the current flight data, the current expected vector deflection angle and a preset feedforward controller based on vector deflection inverse model compensation; wherein the vector deflection inverse model is built and updated based on historical flight data of the aircraft;
And performing flight control of a fluid thrust vector on the aircraft based on the current valve opening instruction.
Further, the determining the current valve opening instruction based on the current flight data, the current expected vector deflection angle and a preset feedforward controller based on vector deflection inverse model compensation includes:
Generating a feedforward control instruction by the feedforward controller based on the current flight data and the current desired vector bias angle;
generating a feedback control instruction through a preset error feedback controller based on the last actual vector deflection angle and the current expected vector deflection angle;
and determining a current valve opening instruction based on the feedforward control instruction and the feedback control instruction.
Further, the vector deflection inverse model is established by adopting a polynomial fitting method; the generating, by the feedforward controller, a feedforward control instruction based on the current flight data and the current desired vector bias angle, including:
judging whether the current expected vector deflection angle is equal to the last actual vector deflection angle;
If the feedforward control instruction is equal to the last actual vector deflection angle, determining that the feedforward control instruction is the last actual valve opening;
If the current engine thrust and the current expected vector deflection angle are not equal to the last actual vector deflection angle, inputting the current engine thrust and the current expected vector deflection angle into the vector deflection inverse model to obtain at least one candidate solution, and determining a target solution meeting a preset condition in the at least one candidate solution as the feedforward control instruction; the preset condition includes that the absolute value of the real number is within a preset numerical range, and the difference between the absolute value and the last actual valve opening is the smallest.
Further, the method further comprises:
Acquiring a plurality of groups of initial flight data obtained by the aircraft through a ground test;
And establishing the vector deflection inverse model based on the plurality of groups of initial flight data by adopting a polynomial fitting method.
Further, after the polynomial fitting method is adopted to build the vector deflection inverse model based on the multiple sets of initial flight data, the method further comprises:
acquiring a plurality of groups of actual flight data of the aircraft in a historical flight process;
Establishing a candidate inverse model based on the plurality of groups of actual flight data by adopting a polynomial fitting method;
And updating the current vector deflection inverse model according to the candidate inverse model to obtain an updated vector deflection inverse model.
Further, the updating the current vector deflection inverse model according to the candidate inverse model to obtain an updated vector deflection inverse model comprises:
calculating to obtain an evaluation index value of the candidate inverse model based on a preset evaluation index function;
Judging whether the evaluation index value is smaller than a preset index threshold value or not;
And if the vector deflection inverse model is smaller than the preset index threshold, carrying out weighted fusion on the candidate inverse model and the current vector deflection inverse model to obtain an updated vector deflection inverse model.
Further, the method further comprises:
if the acquired actual flight data are larger than or equal to the preset index threshold value, re-executing the step of acquiring a plurality of groups of actual flight data of the aircraft in the historical flight process; and the preset index threshold value is in negative correlation with the data quantity of the plurality of groups of actual flight data and the accuracy of the vector deflection inverse model.
In a second aspect, an embodiment of the present invention further provides a flight control device based on a fluid thrust vector, including:
The acquisition module is used for acquiring current flight data of the aircraft and a current expected vector deflection angle of the fluid thrust vector; the current flight data comprise current engine thrust, a last actual vector deflection angle at the last moment and a last actual valve opening;
The determining module is used for determining a current valve opening instruction based on the current flight data, the current expected vector deflection angle and a preset feedforward controller based on vector deflection inverse model compensation; wherein the vector deflection inverse model is built and updated based on historical flight data of the aircraft;
And the control module is used for controlling the flight of the fluid thrust vector on the basis of the current valve opening instruction.
In a third aspect, an embodiment of the present invention further provides a control device, including a memory, and a processor, where the memory stores a computer program that can be run on the processor, and the processor implements the flight control method based on the fluid thrust vector according to the first aspect when executing the computer program.
In a fourth aspect, embodiments of the present invention further provide a computer readable storage medium having a computer program stored thereon, the computer program when executed by a processor performing the fluid thrust vector-based flight control method of the first aspect.
The flight control method, the device and the control equipment based on the fluid thrust vector can acquire the current flight data of the aircraft and the current expected vector deflection angle of the fluid thrust vector; the current flight data comprise the current engine thrust, the last actual vector deflection angle at the last moment and the last actual valve opening; determining a current valve opening instruction based on current flight data, a current expected vector deflection angle and a preset feedforward controller based on vector deflection inverse model compensation; the vector deflection inverse model is established and updated based on historical flight data of the aircraft; and performing flight control of the fluid thrust vector on the aircraft based on the current valve opening instruction. The vector deflection inverse model is built and updated based on historical flight data of the aircraft, the vector deflection inverse model is used as a basis of feedforward control, and then a current valve opening instruction required by the flight control is obtained, on one hand, hysteresis nonlinear inhibition of fluid thrust vector control is realized through feedforward control, and on the other hand, the vector deflection inverse model is built and continuously and iteratively updated through the historical flight data, so that the control precision of the fluid thrust vector is improved, and the problem of stability reduction of a control system caused by insufficient model precision and hysteresis nonlinearity is solved.
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In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings that are needed in the description of the embodiments or the prior art will be briefly described, and it is obvious that the drawings in the description below are some embodiments of the present invention, and other drawings can be obtained according to the drawings without inventive effort for a person skilled in the art.
FIG. 1 is a schematic diagram of a fluid thrust vector hysteresis model according to an embodiment of the present invention;
FIG. 2 is a schematic flow chart of a flight control method based on a fluid thrust vector according to an embodiment of the present invention;
FIG. 3 is a schematic technical block diagram of a flight control method based on a fluid thrust vector according to an embodiment of the present invention;
FIG. 4 is a schematic flow chart of determining a feedforward control command in a flight control method based on a fluid thrust vector according to an embodiment of the present invention;
FIG. 5 is a schematic structural diagram of a flight control device based on a fluid thrust vector according to an embodiment of the present invention;
Fig. 6 is a schematic structural diagram of a control device according to an embodiment of the present invention.
Detailed Description
The technical solutions of the present invention will be clearly and completely described in connection with the embodiments, and it is apparent that the described embodiments are some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
FIG. 1 is a schematic diagram of a fluid thrust vector hysteresis model according to an embodiment of the present invention, wherein an abscissa δ represents a valve opening, an ordinate ε represents an actual vector deflection angle, a coanda process is a process in which the valve opening varies from 0 to 1 or 0 to-1, and a coanda process is a process in which the valve opening varies from 1 to 0 or-1 to 0; it should be noted that, the actual curve of the fluid thrust vector hysteresis model is not an arc, and fig. 1 is only schematic. At present, no technology for carrying out compound control on the hysteresis nonlinearity of a fluid thrust vector exists, but a control scheme for designing some common hysteresis models (such as Duhem models or Bouc-wen models) exists, however, the inverse model of the hysteresis model in the control scheme is completely dependent on an established hysteresis model, and has no model adaptability, and when the actual situation is greatly different from the established hysteresis model, the control precision is greatly reduced, and even the control instability risks exist.
For schemes for improving the accuracy of the inverse model, two types are currently included: 1) For the parametric model (i.e. the inverse model belongs to the parametric model), the influencing factors are coupled into the parametric model as variables, however, the scheme increases the number of parameters, has low precision, and cannot explore how the influence of a single factor on the damping characteristics changes with the changes of other factors. 2) Model parameters are learned online and updated in real time, for example, a new inversion model of the magnetorheological damper based on network inversion is adopted, but the model is not updated by the scheme, only input variables in the inversion process are updated, and the model accuracy is still not high; for another example, the model can be adjusted to describe the dynamic characteristic of the magnetorheological damper along with the change of external excitation, but the inverse model is obtained by directly inverting the model based on the hyperbolic tangent function, errors exist, global updating is performed, and the calculation cost is high. In general, both types of schemes only study the problem of updating the inverse model, can approach the real model to a great extent, but still have errors.
Overall, the objective drawbacks of the prior art are summarized as follows:
1. There is currently no control method for suppressing the nonlinearity of the fluid thrust vector. Moreover, the fluid thrust vector has insufficient model accuracy and hysteresis nonlinearities, which can lead to reduced stability of the control system.
2. The common hysteresis suppression scheme is basically based on a known hysteresis model, and the inverse model is not updated. Once the actual situation has a large difference from the established model, there is a risk that the control accuracy is greatly reduced or even the control is unstable.
3. In the inverse model updating scheme, the accuracy of part of the research scheme is low, the parameter number is increased, and the calculation cost is increased. In addition, the research scheme only updates the input parameters of the inverse model, and does not update the model itself. In the research scheme for directly updating the model, the inverse model is obtained by directly inverting the model based on the hyperbolic tangent function, errors exist, global calculation is performed, and the calculation cost is greatly increased in the updating process.
Based on the above, the embodiment of the invention provides a flight control method, a device and control equipment based on a fluid thrust vector, which provides a fluid thrust vector compound control technology, and can be used for solving the problem of stability reduction of a control system caused by insufficient model precision and hysteresis nonlinearity.
For the convenience of understanding the present embodiment, a detailed description will be given of a flight control method based on a fluid thrust vector according to an embodiment of the present invention.
Embodiments of the present invention provide a method of flight control based on fluid thrust vectors, which may be performed by a control device in an aircraft. Referring to fig. 2, a flow chart of a flight control method based on a fluid thrust vector is shown, and the method mainly includes the following steps S210 to S230:
Step S210, acquiring current flight data of an aircraft and a current expected vector deflection angle of a fluid thrust vector; the current flight data comprise the current engine thrust, the last actual vector deflection angle at the last moment and the last actual valve opening.
The vector angle of the fluid thrust vector, the adjustable valve opening, the engine thrust and the like can be measured and calculated to obtain the current engine thrust, the last actual vector deflection angle at the last moment and the last actual valve opening at the last moment. The current expected vector deflection angle is calculated by relevant flight demand data, and the embodiment of the invention does not limit the source of the current expected vector deflection angle.
Step S220, determining a current valve opening instruction based on current flight data, a current expected vector deflection angle and a preset feedforward controller based on vector deflection inverse model compensation; wherein the vector yaw inverse model is built and updated based on historical flight data of the aircraft.
In order to improve the control accuracy, the current valve opening instruction can be determined by combining model feedforward and error feedback. Based on this, step S220 may be implemented as follows: generating a feedforward control instruction by a feedforward controller based on the current flight data and the current expected vector bias angle; generating a feedback control instruction through a preset error feedback controller based on the last actual vector deflection angle and the current expected vector deflection angle; and determining a current valve opening instruction based on the feedforward control instruction and the feedback control instruction.
Alternatively, the vector deflection inverse model may be established by using a polynomial fitting method, and considering that the polynomial fitting may have a multi-solution problem in the inverse solution process, based on this, the feedforward control instruction may be obtained by: judging whether the current expected vector deflection angle is equal to the last actual vector deflection angle; if the feedforward control instruction is equal to the last actual vector deflection angle, determining the feedforward control instruction as the last actual valve opening; if the current engine thrust and the current expected vector deflection angle are not equal to the last actual vector deflection angle, inputting the current engine thrust and the current expected vector deflection angle into a vector deflection inverse model to obtain at least one candidate solution, and determining a target solution meeting a preset condition in the at least one candidate solution as a feedforward control instruction; the preset condition includes that the absolute value is within a preset numerical range and the difference between the absolute value and the last actual valve opening is the smallest.
The preset numerical range may be set according to actual requirements, for example, the preset numerical range is [0,1], and if the absolute value of a candidate solution is less than or equal to 1, the absolute value of the candidate solution is within the preset numerical range.
The current valve opening instruction is fused with the feedforward control instruction and the feedback control instruction, so that the control precision can be improved. It should be noted that, the specific determination mode of the current valve opening instruction is not limited in the embodiment of the present invention, for example, the current valve opening instruction may be obtained by weighting and summing the feedforward control instruction and the feedback control instruction.
Step S230, performing flight control of the fluid thrust vector on the aircraft based on the current valve opening command.
The current valve opening instruction can be output to the motor model, so that the valve opening of the aircraft can be controlled, the static pressure of the nozzle wall can be changed by changing the valve opening, the vector angle is changed, and the flight control of the fluid thrust vector of the aircraft is realized.
The flight control method based on the fluid thrust vector provided by the embodiment of the invention can acquire the current flight data of an aircraft and the current expected vector deflection angle of the fluid thrust vector; the current flight data comprise the current engine thrust, the last actual vector deflection angle at the last moment and the last actual valve opening; determining a current valve opening instruction based on current flight data, a current expected vector deflection angle and a preset feedforward controller based on vector deflection inverse model compensation; the vector deflection inverse model is established and updated based on historical flight data of the aircraft; and performing flight control of the fluid thrust vector on the aircraft based on the current valve opening instruction. The vector deflection inverse model is built and updated based on historical flight data of the aircraft, the vector deflection inverse model is used as a basis of feedforward control, and then a current valve opening instruction required by the flight control is obtained, on one hand, hysteresis nonlinear inhibition of fluid thrust vector control is realized through feedforward control, and on the other hand, the vector deflection inverse model is built and continuously and iteratively updated through the historical flight data, so that the control precision of the fluid thrust vector is improved, and the problem of stability reduction of a control system caused by insufficient model precision and hysteresis nonlinearity is solved.
The embodiment of the invention also provides a method for establishing the vector deflection inverse model, which comprises the following steps: acquiring a plurality of groups of initial flight data obtained by an aircraft through a ground test; and establishing a vector deflection inverse model based on a plurality of groups of initial flight data by adopting a polynomial fitting method. Each set of initial flight data comprises an actual vector deflection angle, an actual valve opening and an engine thrust at the same time.
The embodiment of the invention also provides an updating mode of the vector deflection inverse model, which comprises the following steps: acquiring a plurality of groups of actual flight data of the aircraft in a historical flight process; a polynomial fitting method is adopted, and a candidate inverse model is established based on a plurality of groups of actual flight data; and updating the current vector deflection inverse model according to the candidate inverse model to obtain an updated vector deflection inverse model.
In consideration of selecting different polynomial orders, the obtained candidate inverse models are different, in order to obtain a unique candidate inverse model, an evaluation index function is predefined in this embodiment, and screening of the candidate inverse model is performed based on the evaluation index value of the candidate inverse model, so as to ensure the accuracy of the updated vector deflection inverse model. Based on this, the updated vector deflection inverse model can be obtained by the following procedure: calculating to obtain an evaluation index value of the candidate inverse model based on a preset evaluation index function; judging whether the evaluation index value is smaller than a preset index threshold value or not; if the vector deflection inverse model is smaller than the preset index threshold value, carrying out weighted fusion on the candidate inverse model and the current vector deflection inverse model to obtain an updated vector deflection inverse model; and if the acquired actual flight data are greater than or equal to the preset index threshold value, re-executing the step of acquiring a plurality of groups of actual flight data of the aircraft in the historical flight process so as to establish a new candidate inverse model.
The preset index threshold is in negative correlation with the data volume of the plurality of groups of actual flight data and the accuracy of the vector deflection inverse model, namely, the larger the data volume of the plurality of groups of actual flight data is, the higher the accuracy of the vector deflection inverse model is, and the smaller the preset index threshold is. When the candidate inverse model and the current vector deflection inverse model are subjected to weighted fusion, the weight of the candidate inverse model can be a preset confidence level, and the confidence level of the candidate inverse model is expressed; the sum of the weights of the current vector deflection inverse model and the weights of the candidate inverse model may be equal to 1. It should be noted that, the weight of the candidate inverse model and the weight of the current vector deflection inverse model may be set according to actual requirements, and are not limited herein, for example, the weight of the candidate inverse model is 0.96, and the weight of the current vector deflection inverse model is 0.04.
For ease of understanding, one possible implementation of the above-described fluid thrust vector-based flight control method is described in detail below.
The embodiment of the invention mainly aims to provide a fluid thrust vector compound control technology so as to solve the problem of system stability reduction caused by insufficient model precision and hysteresis nonlinearity.
The embodiment of the invention provides an iterative inverse model compound control scheme based on hysteresis nonlinear fluid thrust vectors, which is shown in fig. 3 and comprises the following steps: a measuring part for measuring and calculating vector angles of fluid thrust vectors, adjustable valve opening, engine thrust and the like to obtain an engine thrust P k at the time of k, an actual vector deflection angle epsilon k-1 at the time of k-1 and an actual valve opening delta k-1, wherein a motor model can control the magnitude of the valve opening based on a current valve opening instruction delta cmd, and further can measure and obtain the actual valve opening delta k at the time of k, the fluid thrust vector model may output the actual vector offset angle epsilon k at time k based on the inputs P k and delta k; the control part is divided into a model feedforward part (i.e. a vector deflection inverse model) and an error feedback part, the model feedforward part (i.e. a feedback controller) generates a feedforward control command delta q according to a reference input epsilon cmd (i.e. a current expected vector deflection angle) and a thrust magnitude P k, the error feedback part (i.e. a feedback controller) generates a feedback control command delta f according to an error e of epsilon cmd and epsilon k-1, and finally delta q and delta f are added to obtain a total control command delta cmd (i.e. a current valve opening command), thereby accurately controlling the vector angle in real time; an inverse model updating section for selecting the record data of the measuring section for a period of time, such as i sets of data from the time of k-i to the time of k-1 (wherein,Considered as a group of data), the optimized parameters are obtained through an inverse model updating algorithm, and the vector deflection inverse model is locally updated by utilizing the optimized parameters, so that the control accuracy of the vector angle is further ensured.
The control objective of this embodiment is a rationally designed valve opening command δ cmd such that the actual vector offset angle ε k of the fluid thrust vector tracks the desired vector offset angle ε cmd. The valve opening command consists of two parts, wherein one part generates a feedforward control command delta q through a vector deflection mathematical model by the current thrust P k, the expected vector deflection angle epsilon cmd and the information of the previous control period (k-1 moment) (namely epsilon k-1 and delta k-1). The other part generates a feedback control command delta f by an error feedback controller. The feedforward control is used for inhibiting hysteresis nonlinearity of the fluid thrust vector, and the feedback control is used for improving control accuracy of the control system. When the control system receives a valve opening instruction, the motor model drives the valve to start working, and due to the existence of motor characteristics, the actual valve opening delta k has certain hysteresis. Finally, the vector deflection inverse model (hereinafter referred to as the inverse model for short) is iteratively updated by utilizing the past flight data, so that the inverse model further approximates to the actual model, and the control precision is further improved.
The algorithm of the three parts is described in detail below.
1. Feedforward controller design based on inverse model compensation
The actual fluid thrust vector model is assumed to be:
（1）
embodiments of the present invention obtain multiple sets of initial flight data based on initial ground tests (where, Considered as a set of data), an inverse model of the fluid thrust vector is established using a polynomial fitting method, expressed as follows:
（2）
Since the polynomial fitting may have a multi-solution problem in the inverse solution process, in order to obtain a unique solution, the solution needs to be screened, and as shown in fig. 4, the feedforward control command δ q is determined by the following procedure:
Inputs are P k、εcmd、δk-1 and epsilon k-1, and whether epsilon cmd is equal to epsilon k-1 is judged; if yes (namely epsilon cmd=εk-1）,δq=δk-1; if no (namely epsilon cmd≠εk-1), delta q (namely delta q=gj（Pk、εcmd) is calculated according to P k、εcmd and formula (2), then whether delta q belongs to a real number R is judged, and if not (namely delta q ∉ R), the complex solution is removed; if yes (i.e., δ q ε R), judging whether |δ q | is less than or equal to 1, if not (i.e., |δ q | > 1), removing out-of-range solutions; if yes (|delta q |is less than or equal to 1), judging whether delta q has multiple solutions, and if not (namely delta q does not have multiple solutions), outputting the unique solution; if yes (i.e. delta q has multiple solutions), searching the solution nearest to the last moment according to the state of the executing mechanism (belonging to the wall attaching process or the wall separating process), and outputting the solution. This results in a unique feedforward control command δ q.
2. Introduction to model update algorithm
Regarding as a set of data, the data amount (i.e. the value of i) required by the model updating algorithm is selected according to the compromise between the calculation time and the required precision, i.e. continuous i sets of data are required for performing one model updating iteration. Processing the i sets of data, ordered according to delta k size, then there is/>. The inverse model from the i sets of data fitted according to the polynomial is assumed to be:
（3）
because different polynomial orders are selected, the h j obtained is different, and in order to obtain a unique solution, an evaluation index function is defined as follows:
（4）
Where k 1（k1 < 0.9) represents the weight, the larger i is, the smaller k 1 is, and the subscript h represents the corresponding model (that is, the data selected may be approximated as the data corresponding to the real model, i.e., the data selected corresponds to the subscript f, although the real model is not known). And the smaller the evaluation index function, the more accurate the model h is in the selected data set.
The iterated model is:
（5）
Wherein, Confidence is expressed to represent confidence in the generated model (because there is an error in the measured data), typically chosen to be greater than 0.95.
Until the model is updated repeatedly, the method is continuously circulated until the evaluation index value is smaller than m, wherein m is related to the data quantity i and the accuracy.
3. Error feedback controller design
The main advantage of the proposed method is that the feedforward part of the control algorithm can make the system approach the required vector deflection angle, but for further improving the control accuracy, an adaptive controller is designed as follows:
（6）
Wherein, Represents motor frequency, t represents time,/>An inverse model representing the actual model, and. Since it is not possible to obtain/>, during the actual flightThus with constantly updated iterations/>To approximately replace it. The adaptive controller design may be rewritten as:
（7）
Since the purpose of the feedback control is to further reduce the error between the desired vector offset and the actual vector offset and the vector offset is more sensitive to the variation of the valve opening, there is a need to set the upper limit v of the feedback control command
（8）
Wherein v <0.01.
It should be noted that, in the embodiment of the present invention, the design of the feedback controller is not limited, and in other embodiments, the feedback controller may be designed as a simple PID controller or other controllers.
The technical key points of the embodiment of the invention include:
1. The model precision is ensured by adopting a local inverse model updating iteration mode, and the control precision of the fluid thrust vector is further improved.
2. The model feedforward control scheme is adopted to inhibit hysteresis nonlinearity of the fluid thrust vector.
3. And the control precision is improved by adopting a feedback technology.
In summary, the main purposes of the embodiments of the present invention are two, one is to realize the hysteresis nonlinear suppression of the fluid thrust vector control, and the other is to improve the vector angle control precision of the fluid thrust vector control, thereby ensuring the accurate control of the model. According to the embodiment of the invention, firstly, an inverse model with lower precision is constructed through data measured on the ground, then the inverse model is used as a basis of feedforward control, and a feedforward control instruction is automatically generated, so that a vector angle is close to a reference instruction within a certain precision range. Meanwhile, in order to improve the precision, a feedback controller is introduced, and generates a feedback control instruction according to the error, so that the opening of the valve is further adjusted, and the control error is reduced. Finally, in order to enable the feedforward instruction to be more approximate to the actual model, the inverse model is iteratively updated by utilizing data acquired in the actual flight process, and the control accuracy of the fluid thrust vector is further ensured. Thus, the problem of hysteresis nonlinearity is solved, and the problem of vector angle control precision is also solved.
Corresponding to the above-mentioned flight control method based on the fluid thrust vector, the embodiment of the present invention further provides a flight control device based on the fluid thrust vector, referring to a schematic structural diagram of the flight control device based on the fluid thrust vector shown in fig. 5, the device includes:
An acquisition module 501 for acquiring current flight data of the aircraft and a current desired vector offset of the fluid thrust vector; the current flight data comprise current engine thrust, a last actual vector deflection angle at the last moment and a last actual valve opening;
a determining module 502, configured to determine a current valve opening instruction based on the current flight data, the current expected vector deviation angle, and a preset feedforward controller based on vector deflection inverse model compensation; wherein the vector deflection inverse model is built and updated based on historical flight data of the aircraft;
and the control module 503 is used for performing flight control of the fluid thrust vector on the aircraft based on the current valve opening instruction.
The flight control device based on the fluid thrust vector provided by the embodiment of the invention can acquire the current flight data of an aircraft and the current expected vector deflection angle of the fluid thrust vector; the current flight data comprise the current engine thrust, the last actual vector deflection angle at the last moment and the last actual valve opening; determining a current valve opening instruction based on current flight data, a current expected vector deflection angle and a preset feedforward controller based on vector deflection inverse model compensation; the vector deflection inverse model is established and updated based on historical flight data of the aircraft; and performing flight control of the fluid thrust vector on the aircraft based on the current valve opening instruction. The vector deflection inverse model is built and updated based on historical flight data of the aircraft, the vector deflection inverse model is used as a basis of feedforward control, and then a current valve opening instruction required by the flight control is obtained, on one hand, hysteresis nonlinear inhibition of fluid thrust vector control is realized through feedforward control, and on the other hand, the vector deflection inverse model is built and continuously and iteratively updated through the historical flight data, so that the control precision of the fluid thrust vector is improved, and the problem of stability reduction of a control system caused by insufficient model precision and hysteresis nonlinearity is solved.
Further, the determining module 502 is specifically configured to: generating a feedforward control instruction by the feedforward controller based on the current flight data and the current desired vector bias angle; generating a feedback control instruction through a preset error feedback controller based on the last actual vector deflection angle and the current expected vector deflection angle; and determining a current valve opening instruction based on the feedforward control instruction and the feedback control instruction.
Further, the vector deflection inverse model is established by adopting a polynomial fitting method; the determining module 502 is further configured to: judging whether the current expected vector deflection angle is equal to the last actual vector deflection angle; if the feedforward control instruction is equal to the last actual vector deflection angle, determining that the feedforward control instruction is the last actual valve opening; if the current engine thrust and the current expected vector deflection angle are not equal to the last actual vector deflection angle, inputting the current engine thrust and the current expected vector deflection angle into the vector deflection inverse model to obtain at least one candidate solution, and determining a target solution meeting a preset condition in the at least one candidate solution as the feedforward control instruction; the preset condition includes that the absolute value of the real number is within a preset numerical range, and the difference between the absolute value and the last actual valve opening is the smallest.
Further, the device further comprises a building module for: acquiring a plurality of groups of initial flight data obtained by the aircraft through a ground test; and establishing the vector deflection inverse model based on the plurality of groups of initial flight data by adopting a polynomial fitting method.
Further, the device further comprises an updating module for: acquiring a plurality of groups of actual flight data of the aircraft in a historical flight process; establishing a candidate inverse model based on the plurality of groups of actual flight data by adopting a polynomial fitting method; and updating the current vector deflection inverse model according to the candidate inverse model to obtain an updated vector deflection inverse model.
Further, the update module is specifically configured to: calculating to obtain an evaluation index value of the candidate inverse model based on a preset evaluation index function; judging whether the evaluation index value is smaller than a preset index threshold value or not; and if the vector deflection inverse model is smaller than the preset index threshold, carrying out weighted fusion on the candidate inverse model and the current vector deflection inverse model to obtain an updated vector deflection inverse model.
Further, the update module is further configured to: if the acquired actual flight data are larger than or equal to the preset index threshold value, re-executing the step of acquiring a plurality of groups of actual flight data of the aircraft in the historical flight process; and the preset index threshold value is in negative correlation with the data quantity of the plurality of groups of actual flight data and the accuracy of the vector deflection inverse model.
The flight control device based on the fluid thrust vector according to the present embodiment has the same implementation principle and technical effects as those of the foregoing flight control method embodiment based on the fluid thrust vector, and for a brief description, reference may be made to corresponding matters in the foregoing flight control method embodiment based on the fluid thrust vector where the portion of the embodiment of the flight control device based on the fluid thrust vector is not mentioned.
As shown in fig. 6, a control device 600 provided in an embodiment of the present invention includes: the flight control device comprises a processor 601, a memory 602 and a bus, wherein the memory 602 stores a computer program capable of running on the processor 601, and when the control device 600 runs, the processor 601 and the memory 602 communicate through the bus, and the processor 601 executes the computer program to realize the flight control method based on the fluid thrust vector.
Specifically, the memory 602 and the processor 601 can be general-purpose memories and processors, which are not particularly limited herein.
Embodiments of the present invention also provide a computer readable storage medium having stored thereon a computer program which, when executed by a processor, performs the fluid thrust vector based flight control method described in the previous method embodiments. The computer-readable storage medium includes: a U-disk, a removable hard disk, a Read-Only Memory (ROM), a RAM, a magnetic disk, or an optical disk, etc., which can store program codes.
Any particular values in all examples shown and described herein are to be construed as merely illustrative and not a limitation, and thus other examples of exemplary embodiments may have different values.
The flowcharts and block diagrams in the figures illustrate the architecture, functionality, and operation of possible implementations of apparatus, methods and computer program products according to various embodiments of the present invention. In this regard, each block in the flowchart or block diagrams may represent a module, segment, or portion of code, which comprises one or more executable instructions for implementing the specified logical function(s). It should also be noted that, in some alternative implementations, the functions noted in the block may occur out of the order noted in the figures. For example, two blocks shown in succession may, in fact, be executed substantially concurrently, or the blocks may sometimes be executed in the reverse order, depending upon the functionality involved. It will also be noted that each block of the block diagrams and/or flowchart illustration, and combinations of blocks in the block diagrams and/or flowchart illustration, can be implemented by special purpose hardware-based systems which perform the specified functions or acts, or combinations of special purpose hardware and computer instructions.
In the several embodiments provided by the present application, it should be understood that the disclosed apparatus and method may be implemented in other manners. The above-described apparatus embodiments are merely illustrative, for example, the division of the units is merely a logical function division, and there may be other manners of division in actual implementation, and for example, multiple units or components may be combined or integrated into another system, or some features may be omitted, or not performed. Alternatively, the coupling or direct coupling or communication connection shown or discussed with each other may be through some communication interface, device or unit indirect coupling or communication connection, which may be in electrical, mechanical or other form.
The units described as separate units may or may not be physically separate, and units shown as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.
In addition, each functional unit in the embodiments of the present invention may be integrated in one processing unit, or each unit may exist alone physically, or two or more units may be integrated in one unit.
Finally, it should be noted that: the above embodiments are only for illustrating the technical solution of the present invention, and not for limiting the same; although the invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some or all of the technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit of the invention.
Claims (8)
1. A fluid thrust vector-based flight control method, comprising:
Acquiring current flight data of an aircraft and a current expected vector deflection angle of a fluid thrust vector; the current flight data comprise current engine thrust, a last actual vector deflection angle at the last moment and a last actual valve opening;
Determining a current valve opening instruction based on the current flight data, the current expected vector deflection angle and a preset feedforward controller based on vector deflection inverse model compensation; wherein the vector deflection inverse model is built and updated based on historical flight data of the aircraft;
Performing flight control of a fluid thrust vector on the aircraft based on the current valve opening instruction;
The determining a current valve opening instruction based on the current flight data, the current expected vector deflection angle and a preset feedforward controller based on vector deflection inverse model compensation comprises the following steps:
Generating a feedforward control instruction by the feedforward controller based on the current flight data and the current desired vector bias angle;
generating a feedback control instruction through a preset error feedback controller based on the last actual vector deflection angle and the current expected vector deflection angle;
determining a current valve opening instruction based on the feedforward control instruction and the feedback control instruction;
The vector deflection inverse model is established by adopting a polynomial fitting method; the generating, by the feedforward controller, a feedforward control instruction based on the current flight data and the current desired vector bias angle, including:
judging whether the current expected vector deflection angle is equal to the last actual vector deflection angle;
If the feedforward control instruction is equal to the last actual vector deflection angle, determining that the feedforward control instruction is the last actual valve opening;
If the current engine thrust and the current expected vector deflection angle are not equal to the last actual vector deflection angle, inputting the current engine thrust and the current expected vector deflection angle into the vector deflection inverse model to obtain at least one candidate solution, and determining a target solution meeting a preset condition in the at least one candidate solution as the feedforward control instruction; the preset condition includes that the absolute value of the real number is within a preset numerical range, and the difference between the absolute value and the last actual valve opening is the smallest.
2. The method according to claim 1, wherein the method further comprises:
Acquiring a plurality of groups of initial flight data obtained by the aircraft through a ground test;
And establishing the vector deflection inverse model based on the plurality of groups of initial flight data by adopting a polynomial fitting method.
3. The method of claim 2, wherein said employing a polynomial fitting method, after said establishing said vector deflection inverse model based on said plurality of sets of initial flight data, further comprises:
acquiring a plurality of groups of actual flight data of the aircraft in a historical flight process;
Establishing a candidate inverse model based on the plurality of groups of actual flight data by adopting a polynomial fitting method;
And updating the current vector deflection inverse model according to the candidate inverse model to obtain an updated vector deflection inverse model.
4. A method according to claim 3, wherein updating the current vector deflection inverse model according to the candidate inverse model results in an updated vector deflection inverse model, comprising:
calculating to obtain an evaluation index value of the candidate inverse model based on a preset evaluation index function;
Judging whether the evaluation index value is smaller than a preset index threshold value or not;
And if the vector deflection inverse model is smaller than the preset index threshold, carrying out weighted fusion on the candidate inverse model and the current vector deflection inverse model to obtain an updated vector deflection inverse model.
5. The method according to claim 4, wherein the method further comprises:
if the acquired actual flight data are larger than or equal to the preset index threshold value, re-executing the step of acquiring a plurality of groups of actual flight data of the aircraft in the historical flight process; and the preset index threshold value is in negative correlation with the data quantity of the plurality of groups of actual flight data and the accuracy of the vector deflection inverse model.
6. A fluid thrust vector-based flight control device, comprising:
The acquisition module is used for acquiring current flight data of the aircraft and a current expected vector deflection angle of the fluid thrust vector; the current flight data comprise current engine thrust, a last actual vector deflection angle at the last moment and a last actual valve opening;
The determining module is used for determining a current valve opening instruction based on the current flight data, the current expected vector deflection angle and a preset feedforward controller based on vector deflection inverse model compensation; wherein the vector deflection inverse model is built and updated based on historical flight data of the aircraft;
The control module is used for performing flight control of a fluid thrust vector on the aircraft based on the current valve opening instruction;
The determining module is further configured to: generating a feedforward control instruction by the feedforward controller based on the current flight data and the current desired vector bias angle; generating a feedback control instruction through a preset error feedback controller based on the last actual vector deflection angle and the current expected vector deflection angle; determining a current valve opening instruction based on the feedforward control instruction and the feedback control instruction;
The vector deflection inverse model is established by adopting a polynomial fitting method; the determining module is further configured to: judging whether the current expected vector deflection angle is equal to the last actual vector deflection angle; if the feedforward control instruction is equal to the last actual vector deflection angle, determining that the feedforward control instruction is the last actual valve opening; if the current engine thrust and the current expected vector deflection angle are not equal to the last actual vector deflection angle, inputting the current engine thrust and the current expected vector deflection angle into the vector deflection inverse model to obtain at least one candidate solution, and determining a target solution meeting a preset condition in the at least one candidate solution as the feedforward control instruction; the preset condition includes that the absolute value of the real number is within a preset numerical range, and the difference between the absolute value and the last actual valve opening is the smallest.
7. A control device comprising a memory, a processor, the memory having stored therein a computer program executable on the processor, wherein the processor, when executing the computer program, implements the fluid thrust vector based flight control method of any one of claims 1-5.
8. A computer readable storage medium having stored thereon a computer program, characterized in that the computer program when executed by a processor performs the fluid thrust vector based flight control method of any one of claims 1-5.
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