CN103823374B - Aircraft multiloop model bunch compound root locus compensating controller method for designing - Google Patents

Abstract

The invention provides a kind of aircraft multiloop model bunch compound root locus compensating controller method for designing, the method directly determines to obtain by frequency sweep flight test the model cluster that amplitude-frequency in whole envelope and phase-frequency characteristic form under given differing heights, Mach number condition; According to the amplitude-frequency nargin in flight envelope and the mark requirement of phase margin army, give corresponding root locus and describe lower Distribution of Closed Loop Poles restriction index, by add plural serial stage delayed-lead compensation controller Distribution of Closed Loop Poles in aircraft whole envelope limit identification Method determination plural serial stage in index and System Discrimination delayed-lead compensation controller sum of series parameter value; The concept that Distribution of Closed Loop Poles under root locus describes limits designs little, the stable low-latitude flying controller of the overshoot meeting full flight envelope.

Description

Design method of aircraft multi-loop model cluster composite root trajectory compensation controller

Technical Field

The invention relates to a design method of an aircraft controller, in particular to a design method of a composite root trajectory compensation controller of an aircraft multi-loop model cluster, and belongs to the fields of measurement and control technology, flight mechanics and the like.

Background

The control of the take-off and landing process of the aircraft plays an important role in flight safety; because the flying speed of the aircraft is greatly changed in the taking-off and landing processes, the aircraft can also face a strong nonlinear problem even according to a longitudinal model; on the other hand, the control rudder of the aircraft has the phenomena of saturation, dead zone and the like; from the consideration of flight safety, when the system flies at ultra-low altitude (such as take-off/landing of an airplane), the controller must ensure that the system has certain stability margin, no overshoot and stability, so that the design of the ultra-low altitude flight controller is very complex, and the design of controlling the airplane cannot be directly applied by the existing control theory.

In the design of modern practical flight controllers, a small part of the design is designed by adopting a state space method, and most of the design is still designed by adopting a modern frequency method represented by a classical frequency domain method represented by PID and an inverse Nyquist array method. The modern control theory is characterized by a state space method, takes analytic calculation as a main means, and takes performance index realization as an optimal modern control theory, and then develops a series of controller design methods such as an optimal control method, a model reference control method, an adaptive control method, a dynamic inverse control method, a feedback linearization method, a direct nonlinear optimization control method, a variable gain control method, a neural network control method, a fuzzy control method, a robust control method, and a multi-method combination control, and the published academic papers are in ten thousands, for example, 2011 GhasemiA designs a reentry aircraft controlled by an adaptive fuzzy sliding mode (GhasemiA, MoradiM, menhajmb.adaptivefuzzylindlecontrolconsignformindelformadelforlow-softvehicle, slip-form engineering, 25(2): 210), and int3 year baotidebeauie designs a nonlinear phase aircraft for a non-linear fuzzy driving system (journal aircraft), fuzzy autonomous vehicle model engineering, model system, fuzzy control system, and intelligent vehicle model simulation system for unmanned aerial vehicle control system, 2013,24(3):499- & 509), many studies only stay in the idealized simulation study stage; the design has three problems that (1) because the ultra-low altitude operation stability test of the aircraft can not be carried out, an accurate mathematical model of a controlled object is difficult to obtain; (2) for evaluating important performance indexes of a flight control system such as stability margin specified by military standards, a state space method can not be expressed in an obvious form like a classical frequency method; (3) the controller structure is too complex, no constraints of actual controllers and flight states are considered, and the designed controller is not physically realizable.

The university scholark systematically and creatively researches how to popularize the frequency domain method into the design of a multivariable system, utilizes the concept of the advantage of the diagonal matrix to convert the multivariable problem into the design problem of a univariate system of a classical method which is well known by people, and then sequentially presents the methods of a Mayne sequence regression method, a MacFarlane characteristic trajectory method, an Owens parallel vector expansion method and the like. Especially when the computer aided design program with graphic display terminal is used, the experience and intelligence of the designer can be fully exerted to design the controller which not only meets the quality requirement, but also is physically realizable and has simple structure; the multivariate frequency method is improved and researched at home and abroad (a multivariate frequency domain design method of a high and high altitude, Rocheng, Shenhui, Huidewen and flexible satellite attitude decoupling controller, aerospace science news, 2007, Vol.28(2), pp 442-447; Lithocarpus, Charpy, Tiaoling cloud, Tilt turning hypersonic cruise aircraft multivariate frequency domain method decoupling design, rocket and guidance science news, 2011, Vol.31(3) and pp 25-28), however, the conservatism of the design method is too large when the uncertain problem of the system is considered, and a reasonable design result cannot be obtained under the condition that the aircraft is restricted by a control rudder.

In summary, the existing control method cannot design a stable low-altitude flight controller with small overshoot according to the stability margin index in the full-flight envelope when the aircraft model changes.

Disclosure of Invention

In order to overcome the technical defects that the existing method can not design a low overshoot and stable low altitude flight controller which accords with the stability margin index in the full flight envelope under the condition that the model change of the aircraft in the full flight envelope is large, the invention provides a design method of a multi-loop model cluster composite root track compensation controller of an aircraft, which directly determines and obtains a model cluster formed by the amplitude-frequency and phase-frequency characteristics in the full envelope through a sweep frequency flight test under the conditions of different given heights and Mach numbers; according to the military standard requirements of amplitude-frequency margin and phase margin in a flight envelope, a closed-loop pole distribution limiting index under the description of a corresponding root track is given, and the series and parameter values of a multi-stage series lag-lead compensation controller are determined by adding the multi-stage series lag-lead compensation controller, the closed-loop pole distribution limiting index in the aircraft envelope and a model identification method in system identification; a low-altitude flight controller which is consistent with the full-flight envelope and is small in overshoot and stable is designed based on the concept of closed-loop pole distribution limitation under root track description.

The technical scheme adopted by the invention for solving the technical problems is as follows: a design method of a composite root trajectory compensation controller of an aircraft multi-loop model cluster is characterized by comprising the following steps:

step 1, directly forming a model cluster of an operation control surface and a flight altitude in a full envelope of an aircraft by amplitude-frequency and phase-frequency characteristics in the full envelope of the aircraft allowed to fly through a sweep frequency flight test under the conditions of different given altitudes and Mach numbers, and obtaining the flutter frequency of the aircraft by crossing the flight envelope to obtain an open-loop transfer function model cluster matrix between the corresponding operation control surface and the flight altitude of the aircraft, wherein the open-loop transfer function model cluster matrix is as follows:

wherein,is composed ofThe method comprises the following steps of (1) square matrix,is a positive integer and is a non-zero integer,is an independent variable of the laplacian transform,is the flying height of the aircraft,is a Mach number of the component (A),is composed ofA single-mode square matrix is adopted,is composed ofA polynomial diagonal matrix of the form,is composed ofA single-mode square matrix is adopted,in order to be a polynomial expression,is a positive integer;

selecting

The conditions are satisfied:

and

wherein,is composed ofThe method comprises the following steps of (1) square matrix,is composed ofA single-mode square matrix is adopted,is composed ofA polynomial diagonal matrix of the form,is composed ofTo (1) aLine and firstThe elements of the column are, in turn,is composed ofTo (1) aLine and firstThe elements of the column are, in turn,,is composed ofA single-mode square matrix is adopted,in order to be a polynomial expression,is a phase angle mathematical sign;

the controller of the aircraft multi-circuit system is set as follows:

wherein,is composed ofThe method comprises the following steps of (1) square matrix,is composed ofA diagonal matrix;is composed ofTo (1) aLine and firstThe elements of the column are, in turn,；

step 2, the controller，The design process of (2) is as follows:

(1) order toThe specific expression form is as follows:

wherein

、

Is a polynomial, s is a variable after a Laplace change commonly used in transfer functions,respectively the altitude and the mach number,is the delay time of the pitch loop,to followThe gain of the variation is varied in such a way that,is a polynomialMiddle followThe cluster of coefficients that are varied is,is a polynomialMiddle followA cluster of coefficients that vary;

(2) the transfer function of the candidate multistage series lag-lead compensation link is as follows:

in the formula,is a constant gain to be determined, N is an integer representing the number of stages of the lag-lead compensation element to be determined,、、、for the time constant to be determined,is a parameter to be determined;

after adding a multi-stage series lag-lead compensation link, the open-loop transfer function of the whole system is as follows:

the corresponding root trajectory equation is:

；

(3) is provided withWherein:is the real part of s,for the imaginary part of s, the imaginary part,is the imaginary symbol; the stability margin index of the system is set as:，whereinis a non-zero real number and is,is a given number;

thus, the stability margin indicator for the system can be converted into: according to

Or

The resulting root trajectory must satisfy，Determining the number of stages N and constant gain of the lag-lead compensation link according to the maximum likelihood method in the system model structure identification under the common constraint of the index and the maximum likelihood criterionTime constant of、、、Parameter to be determined。

The invention has the beneficial effects that: starting from the concept of closed-loop pole distribution limitation under the description of a root track, parameters of a multi-stage series lag-lead compensation controller are determined in a full flight envelope according to requirements meeting the given closed-loop pole distribution limitation and a model identification method by adding the multi-stage series lag-lead compensation controller, and a stable low-altitude flight controller which meets the full flight envelope and has small overshoot is designed.

The present invention will be described in detail with reference to examples.

Detailed Description

Step 1, linear sweep frequency signals are used under the conditions of different given altitudes and Mach numbers（In order to be the starting frequency,in order to cut-off the frequency of the frequency,，as sweep time) or log swept signals（In order to be the starting frequency,in order to cut-off the frequency of the frequency,and T is sweep frequency time), the amplitude-frequency and phase-frequency characteristics in a full envelope of the aircraft allowed to fly can be directly obtained, the flutter frequency of the aircraft can be obtained by crossing the flight envelope, and an open-loop transfer function model cluster matrix between the corresponding aircraft control surface and the flight altitude is obtained as follows:

wherein,is composed ofThe method comprises the following steps of (1) square matrix,is a positive integer and is a non-zero integer,is an independent variable of the laplacian transform,is the flying height of the aircraft,is a Mach number of the component (A),is composed ofA single-mode square matrix is adopted,is composed ofA polynomial diagonal matrix of the form,is composed ofA single-mode square matrix is adopted,in order to be a polynomial expression,is a positive integer;

selecting

The conditions are satisfied:

and

wherein,is composed ofThe method comprises the following steps of (1) square matrix,is composed ofA single-mode square matrix is adopted,is composed ofA polynomial diagonal matrix of the form,is composed ofTo (1) aLine and firstThe elements of the column are, in turn,is composed ofTo (1) aLine and firstThe elements of the column are, in turn,,is composed ofA single-mode square matrix is adopted,in order to be a polynomial expression,is a phase angle mathematical sign;

the controller of the aircraft multi-circuit system is set as follows:

wherein,is composed ofThe method comprises the following steps of (1) square matrix,is composed ofA diagonal matrix;is composed ofTo (1) aLine and firstThe elements of the column are, in turn,；

step 2, the controller，The design process of (2) is as follows:

(1) order toThe specific expression form is as follows:

wherein

、

Is a polynomial, s is a variable after a Laplace change commonly used in transfer functions,respectively the altitude and the mach number,is the delay time of the pitch loop,to followThe gain of the variation is varied in such a way that,is a polynomialMiddle followThe cluster of coefficients that are varied is,is a polynomialMiddle followA cluster of coefficients that vary;

(2) the transfer function of the candidate multistage series lag-lead compensation link is as follows:

in the formula,is a constant gain to be determined, N is an integer representing the number of stages of the lag-lead compensation element to be determined,、、、for the time constant to be determined,is a parameter to be determined;

after adding a multi-stage series lag-lead compensation link, the open-loop transfer function of the whole system is as follows:

the corresponding root trajectory equation is:

；

(3) is provided withWherein:is the real part of s,for the imaginary part of s, the imaginary part,is the imaginary symbol; the stability margin index of the system is set as:，whereinis a non-zero real number and is,is a given number;

thus, the stability margin indicator for the system can be converted into: according to

Or

The resulting root trajectory must satisfy，Under the common constraint of the index and the maximum likelihood criterion, the maximum in the structure identification of the system model is identifiedLikelihood method for determining series N and constant gain of lag-lead compensation linkTime constant of、、、Parameter to be determined。

Claims (1)

1. A design method of a composite root trajectory compensation controller of an aircraft multi-loop model cluster is characterized by comprising the following steps:

step 1, directly forming a model cluster of an operation control surface and a flight altitude in a full envelope of an aircraft by amplitude-frequency and phase-frequency characteristics in the full envelope of the aircraft allowed to fly through a sweep frequency flight test under the conditions of different given altitudes and Mach numbers, and obtaining the flutter frequency of the aircraft by crossing the flight envelope to obtain an open-loop transfer function model cluster matrix between the corresponding operation control surface and the flight altitude of the aircraft, wherein the open-loop transfer function model cluster matrix is as follows:

wherein,is composed ofThe method comprises the following steps of (1) square matrix,is a positive integer and is a non-zero integer,is an independent variable of the laplacian transform,is the flying height of the aircraft,is a Mach number of the component (A),is composed ofA single-mode square matrix is adopted,is composed ofA polynomial diagonal matrix of the form,is composed ofA single-mode square matrix is adopted,in order to be a polynomial expression,is a positive integer;

selecting

The conditions are satisfied:

and

wherein,is composed ofThe method comprises the following steps of (1) square matrix,is composed ofA single-mode square matrix is adopted,is composed ofA polynomial diagonal matrix of the form,is composed ofTo (1) aLine and firstThe elements of the column are, in turn,is composed ofTo (1) aLine and firstThe elements of the column are, in turn,,is composed ofA single-mode square matrix is adopted,in order to be a polynomial expression,is a phase angle mathematical sign;

the controller of the aircraft multi-circuit system is set as follows:

wherein,is composed ofThe method comprises the following steps of (1) square matrix,is composed ofA diagonal matrix;is composed ofTo (1) aLine and firstThe elements of the column are, in turn,；

step 2, the controller，The design process of (2) is as follows:

(1) order toThe specific expression form is as follows:

wherein

、

Is a polynomial, s is a variable after a Laplace change commonly used in transfer functions,respectively the altitude and the mach number,is the delay time of the pitch loop,to followThe gain of the variation is varied in such a way that,is a polynomialMiddle followThe cluster of coefficients that are varied is,is a polynomialMiddle followA cluster of coefficients that vary;

(2) the transfer function of the candidate multistage series lag-lead compensation link is as follows:

in the formula,is a constant gain to be determined, N is an integer representing the number of stages of the lag-lead compensation element to be determined,、、、for the time constant to be determined,is a parameter to be determined;

after adding a multi-stage series lag-lead compensation link, the open-loop transfer function of the whole system is as follows:

the corresponding root trajectory equation is:

；

(3) is provided withWherein:is the real part of s,for the imaginary part of s, the imaginary part,is the imaginary symbol; the stability margin index of the system is set as:，whereinis a non-zero real number and is,is a given number;

thus, the stability margin indicator for the system can be converted into: according to

Or

The resulting root trajectory must satisfy，Determining the number of stages N and constant gain of the lag-lead compensation link according to the maximum likelihood method in the system model structure identification under the common constraint of the index and the maximum likelihood criterionTime constant of、、、Parameter to be determined。