RU2434785C1 - Aircraft pitch angle bank angular speed limiting automatic control system - Google Patents

Abstract

FIELD: transport. ^ SUBSTANCE: invention relates to ACS for control over aircraft pitch angle. Pitch angle and angle of attach limitation ACS comprises setter of pitch angle and computer of pitch angle autopilot, servo drive its output signal defining the angle of aircraft elevator deflection, aircraft pitch transducer, setter of maximum angle of attack, computer of angle of attack limitation and algebraic selector of maximum signal, and transducer of aircraft angular speed. Aircraft pitch angle transducer output is connected to second input of pitch angle autopilot computer. Maximum signal selector output is connected to servo drive input. Aircraft bank angle transducer output is connected to third input of bank angle autopilot computer. Bank angle autopilot computer output is connected with second input of algebraic selector of maximum signal. ^ EFFECT: accurate limitation of angle of attack and smooth transition processes in ACS. ^ 2 dwg

Description

The invention relates to the field of automatic control systems (ACS) of the pitch angle of an aircraft (LA).

Known self-propelled guns that ensure the development of a given pitch angle of the aircraft with the help of an autopilot acting on the angle of deviation of the elevator of the aircraft [1. Bodner V.A. Control systems for aircraft. - M.: Mechanical Engineering, 1973. - 506 p. Page 101, Fig. 3.9; 2. Krasovsky A.A. Automatic flight control systems and their analytical design. - M .: Nauka, 1973. - 560 p. Page 179, Fig. 5.2; 3. Mikhalev I.A., Okoyemov B.N., Chikulaev M.S. Automatic aircraft control systems. - M.: Mechanical Engineering, 1987. - p. 240. P.192, fig.14.2, p.194, fig.14.4, p.198, fig.14.7, p.201, fig.14.9].

Closest to the technical result achieved, selected as a prototype, the self-propelled gun is adopted by the pitch angle of the aircraft, which implements an astatic control law with high-speed feedback, comprising a pitch angle adjuster and a pitch angle autopilot calculator, a servo drive whose output signal determines the angle of deviation of the elevator apparatus, the pitch angle sensor of the aircraft, having an output connected to the second input of the pitch angle autopilot calculator [V. Bodner Control systems for aircraft. - M. Mechanical Engineering, 1973. - 506 p. Page 101, Fig. 3.9].

This self-propelled guns provides good static and dynamic characteristics of the aircraft pitch angle control channel, but does not allow limiting the value of the angle of attack, which can lead to unacceptable aerodynamic characteristics of the aircraft and violate flight safety when maneuvering at large angles of attack.

As you know, one of the most important restrictions when flying an aircraft is to limit the angle of attack. The range of operational angles of attack is between the maximum permissible angles of attack (α _add.min and α _add.max [Mikhalev I.A., Okoyemov B.N., Chikulaev M.S. Systems for automatic control of an aircraft. - M.: Mechanical Engineering, 1987 . - p. 240. P. 42, Fig. 4.1].

The task to be solved by the claimed invention is aimed at providing the necessary accuracy of limiting the angle of attack by including in the ACS the pitch angle of the aircraft with an automatic limiter using an algebraic selector of the maximum signal.

The task is achieved by the fact that in the automatic control system of the pitch angle and limitation of the angle of attack of the aircraft, comprising a pitch angle adjuster and a pitch angle autopilot calculator, a servo drive, the output signal of which determines the steering angle of the aircraft, pitch angle sensor of the aircraft, having an output connected to the second input of the pitch angle autopilot calculator, in contrast to the prototype, additionally connected in series f the maximum angle of attack adjuster, the calculator of the automatic machine for limiting the angle of attack and the minimum signal selector, the output of which is connected to the input of the servo drive, the angular velocity sensor of the roll of the aircraft having an output connected to the second input of the computer of the automatic machine for limiting the angle of attack, the output of the automatic pitch calculator is connected to the second input of the minimum signal selector.

The invention is illustrated by drawings.

Figure 1 presents the structural diagram of the inventive system of automatic control of the pitch angle and the limitation of the angle of attack of the aircraft.

Figure 2 presents the results of the simulation of transients: 2a - graphs of transients in self-propelled guns with pitch angle ϑ without automatic machine to limit the angle of attack α, 2b - graphs of transients in self-propelled guns with pitch angle ϑ with automatic machine for limiting angle of attack α.

A system for automatically controlling the pitch angle and limiting the angle of attack of the aircraft, comprising a pitch angle adjuster 1 and a pitch angle autopilot calculator 2, a servo drive 3, the output signal of which determines the elevator angle deviation of the aircraft 4, pitch angle sensor 5 of the aircraft 4, having the output connected to the second input of the calculator of the autopilot pitch angle 2, according to the invention contains serially connected setter maximum angle of attack 6, the calculator an automatic machine for limiting the angle of attack 7 and an algebraic selector for the maximum signal 8, the output of which is connected to the input of the servo 3, an angular velocity sensor 9 of the aircraft 4, having an output connected to the second input of the automatic machine for limiting the angle of attack 7, the output of the automatic pitch calculator 2 is connected to the second input of the algebraic selector of the maximum signal 8.

Limiting the angle of attack in the reduced system is achieved by introducing into its structure an automaton of limiting the angle of attack and the algebraic selector of the maximum signal.

The automatic pitch angle control system with a calculator of the machine for limiting the angle of attack works as follows.

The signal of the given pitch angle ϑ _rear from the output of the pitch angle adjuster 1 is fed to the first input of the pitch angle calculator 2, the second input of which receives the signal of the current pitch angle ϑ from the output of pitch angle sensor 5. A signal is generated at the output of the pitch angle calculator 2

arriving at one of the inputs of the algebraic selector of the maximum signal 8.

The signal of the specified maximum angle of attack α _ogre from the output of the master unit of maximum angle of attack 6 is fed to the first input of the calculator of the machine for limiting the angle of attack 7, the second input of which receives the signal of the current value of the angle of attack α from the output of the sensor for the angle of attack 9. At the output of the computer 7 signal is generated

,

,

coming to the other of the two inputs of the algebraic selector of the maximum signal 8.

To build self-propelled guns with limited parameters of aircraft, you can use logical devices that implement algorithms for algebraic channel selection. Typically, the principle of selection is applied, according to which the parameter of the multidimensional control object is adjusted, which is closest to the value determined by the control program [Integrated systems for automatic control of aircraft power plants. / Ed. A.A.Shevyakova. - M.: Mechanical Engineering, 1983. - 283 p. Pages 110-111]. Such selection is implemented using algebraic selectors.

In order for the adjustable parameters not to exceed the maximum allowable values (upper limit), the selector must skip the control signal corresponding to the minimum value of the control signal. Such selection is called minimum selection, and the selector is called the minimum control signal selector.

If the minimum parameter values are limited (lower limit), preference is given to the parameter regulator, which requires the highest control signal to be maintained, i.e. selection is carried out to the maximum. In this case, the maximum control signal selector is used.

Such a classification of algebraic selectors is valid if the transmission coefficient of the control object is greater than zero. If the transmission coefficient of the control object is less than zero, the logic of the algebraic selector must be the opposite. As you know, the equation and the transfer functions of the aircraft in terms of pitch and angle of attack includes a minus sign when changing the angle of deviation of the elevator δ _in [1. Bodner V.A. Control systems for aircraft. - M. Mechanical Engineering, 1973. - 506 p. Pg. 28; 2. Krasovsky A.A. Automatic flight control systems and their analytical design. - M .: Nauka, 1973 - 560 p. Page 37]. Therefore, the algebraic selector of the maximum signal 9 should be used in the system under consideration.

Regarding the difference of the input signals ε = U ₁ -U _{2, the} expression describing the operation of the algebraic selector of two quantities is converted using the module selection operation as follows:

where µ = 1 for the selector of the maximum signal; µ = -1 for the minimum signal selector.

Selectors are introduced into the ACS for smooth switching of control channels and provide in all operating conditions the control action of only one of several control channels that are included in the work depending on the operating mode of the control object. Moreover, each of the control channels operates autonomously and its parameters are usually selected without regard to interaction with other channels. This allows you to maintain the static accuracy and stability margins inherent in individual control channels.

Consequently, the algebraic selector ensures smooth switching from one channel to another, for example, from autopilot to automatic control and back to autopilot.

The output signal U of the algebraic selector of the maximum signal 8 is fed to the input of the astatic servo 3 with the transfer function

,

,

changing the angle of deviation of the elevator δ _{in the} aircraft 4:

.

.

Here is the synthesis of a system for automatically controlling the pitch angle and limiting the angle of attack of the aircraft.

Analytical synthesis of the gear ratios of the autopilot and automatic control based on the specified quality of self-propelled guns is conveniently carried out using the standard transient response method [V. Petunin Synthesis of autopilot pitch control channel laws. // Bulletin of USATU, series "Management, computer engineering and informatics". 2007. Volume 9, No 2 (20). S.25-31]. In this case, the equality of the transfer functions of the original Φ (p) and the desired systems Φ * (p) should be satisfied:

.

.

The transfer function of the aircraft in pitch angle ϑ when controlling the elevator δ _in [V. Bodner Control systems for aircraft. - M.: Mechanical Engineering, 1973. - 506 p. Page 28]:

.

.

The law of control of astatic autopilot pitch angle with high-speed feedback:

,

,

- передаточные числа автопилота.where k _ϑ ,

,

,

- gear ratios of autopilot.

The synthesis of an astatic pitch angle autopilot with high-speed feedback is considered in detail in [Petunin V.I. Synthesis of autopilot pitch control channel laws. // Bulletin of USATU, series "Management, computer engineering and informatics". 2007. Volume 9, No 2 (20). S.25-31].

The transfer function of the aircraft according to the angle of attack α when controlling the elevator δ _in [V. Bodner Control systems for aircraft. - M.: Mechanical Engineering, 1973. - 506 p. Page 28]:

.

.

The control law of the automatic machine for limiting the angle of attack:

,

,

; k

- передаточные числа автомата ограничения.where k _α ; k

; k

- gear ratios of the automatic restriction.

Transfer function of a closed system by angle of attack:

Desired transfer function of a closed system by angle of attack:

.

.

Then the gear ratios of the automatic restriction:

.

.

The synthesis results are confirmed by the results of simulations of transients in the inventive system of automatic control of the pitch angle and limitation of the angle of attack of the aircraft, presented in figure 2, where the defining effects of the channels: ϑ _ass = 1; α _ogre = 0.2. The transients 2a obtained in the self-propelled guns with a roll angle without an automatic machine for limiting the angular pitch speed are not satisfactory, since they have a throw in the angle of attack. The transients 2b obtained in the self-propelled guns with a pitch angle with an automatic machine for limiting the angle of attack are satisfactory, since they show the necessary accuracy of the limitation α≤α _ogre = 0.2 and good quality control in the channel switching modes of the system.

So, the claimed invention allows, due to the introduction of the angle of attack of an automatic machine with the angle of attack of the angle of attack using the algebraic selector of the maximum signal into the structure of the ACS, to provide the necessary accuracy of limiting the angle of attack and smooth transients when switching channels.

Claims (1)

A system for automatically controlling the pitch angle and limiting the angle of attack of the aircraft, comprising a pitch angle adjuster and a pitch angle autopilot calculator, a servo drive whose output signal determines the angle of elevation of the aircraft, a pitch angle sensor of the aircraft having an output connected to the second input pitch angle autopilot calculator, characterized in that it further comprises a serially connected maximum angle of attack adjuster, the extender of the automatic machine for limiting the angle of attack and the algebraic selector of the maximum signal, the output of which is connected to the input of the servo drive, the sensor of angular velocity of the roll of the aircraft, having an output connected to the second input of the calculator for the machine for limiting the angle of attack, the output of the calculator for autopilot of the pitch angle is connected to the second input of the algebraic selector of the maximum signal.

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