RU2180131C1 - Method of single-channel control in longitudinal motion of light ground effect craft - Google Patents

Abstract

FIELD: automatic control over flight of aircraft. SUBSTANCE: technical result of proposal lies in reduction of deviation from reference flight altitude and balanced value of pitch angle under effect of disturbance and in decrease of time of return of ground effect craft to reference flight altitude and to balanced value of pitch angle on completion of effect of disturbance. Method consists in measurement of pitch angle, angular velocity, in formation of control signals proportional to pitch angle and angular acceleration and in formation of non- linear control signal in which value of damping factor depends on sign and value of pitch angle, on sign and value of angular velocity. Control signals are summed up and fed to control unit directly acting on elevator. EFFECT: reduced deviation from reference flight altitude. 5 dwg

Description

 The invention relates to automatic flight control systems and can be used to reduce the deviation of the ekranoplan flight altitude from the balancing value, as well as to reduce the time of transient ekranoplan operations by pitch angle and height.

 There is a method of two-channel control of the longitudinal movement of ekranoplanes (Diomidov B. B. Automatic control of the movement of ekranoplanes. - SPb. SSC RF-CRI Elektropribor, 1996) - [1, p. 86]. It includes measuring the current pitch angle, angular velocity, flight altitude, vertical speed and the formation of control signals proportional to these values, which are fed to the actuators - elevator and flap drives.

Also known is a device for two-channel control of the longitudinal movement of an ekranoplan using the elevator channel and the flaps channel [1, p. 174]. It contains an angle sensor for obtaining a pitch angle value, an angular velocity sensor for determining the angular velocity ω _Z , a radio altimeter for receiving a signal H proportional to the flight altitude above the underlying surface, amplifiers for generating control signals and steering units acting on the elevator and flaps respectively.

 The known method of controlling the longitudinal movement of an ekranoplane and a device for its implementation are mainly applicable to ekranoplans of large sizes, the flight of which is carried out at sufficiently high altitudes. Due to the fact that the error in measuring the current flight altitude by radio altimeters designed for ekranoplanes is about 0.1 m in the altitude range 0-15 m (A. Nebylov, Measurement of flight parameters near the sea surface, SPbGAAP. SPb., 1994) - [2 , p. 79], then such a measurement error is unacceptable for light ekranoplanes flying at altitudes of 0.3-1 m above the surface. A two-channel control scheme is not always acceptable, since light winged wagons may not have flaps designed to directly control the flight altitude (having the ability to deviate in opposite directions from the neutral). The introduction of a two-channel control scheme is also limited by the requirements of weight and size indicators for lightweight ekranoplanes.

 For comparative analysis with the claimed invention, a method for autonomously controlling the angular movement of an aircraft was adopted, which includes measuring the pitch angle, angular velocity and angular acceleration relative to the OZ axis and generating control signals proportional to the measured values supplied to the elevator drive (On-board flight control systems / under Edited by Yu. V. Bayborodin - M .: Transport, 1975) - [3, p. 254].

 There is also known a device for single-channel pitch angle control (used in the AP-15T autopilot), comprising a pitch angle sensor, the output of which is connected to the first input of the adder, an angular velocity sensor connected to the second input of the adder, an angular acceleration sensor connected to the third input of the adder, serially connected amplifier, the input of which is connected to the output of the adder, and the steering unit [3, p. 254].

будет достаточно мала. Но при наличии большого демпфирования относительно поперечной оси экраноплан будет медленнее возвращаться к балансировочному значению угла тангажа. Следовательно, более длительное время будет существовать вертикальная скорость центра масс экраноплана

что вызовет большее отклонение экраноплана по высоте после окончания действия возмущения. Для уменьшения отклонения экраноплана по высоте после прекращения действия возмущения на этапе возвращения экраноплана к балансировочному значению угла тангажа желательно иметь меньшее значение коэффициента демпфирования.The aforementioned method and device for single-channel longitudinal motion control can be directly applied to a light winged craft. At the same time, due to the ekranoplan’s own property, the stabilization of the reference altitude, the value of which is uniquely determined by the flight speed and the balancing deviation of the elevator, will be indirectly carried out to return to the reference altitude. But with this method and control device, there will be sufficiently large deviations of the winged wing from the reference flight altitude and the balancing value of the pitch angle under the action of perturbations. To reduce the deviations of the ekranoplan from the balancing (reference) flight altitude and the balancing value of the pitch angle under the action of disturbances, it is possible, without changing the structure of the autopilot, by increasing the damping coefficient of the ekranoplan relative to the transverse axis. In this case, the perturbations acting relative to the transverse axis (wave impact) will not cause a large deviation of the pitch angle relative to the balancing position, and therefore the winged wing will deviate little from the reference flight altitude, since the vertical speed due to the relation

will be small enough. But in the presence of large damping relative to the transverse axis, the ekranoplan will slowly return to the balancing value of the pitch angle. Therefore, for a longer time there will be a vertical velocity of the center of mass of the winged craft

which will cause a greater deviation of the ekranoplan in height after the end of the disturbance. To reduce the deviation of the ekranoplan in height after the cessation of the disturbance at the stage of the return of the ekranoplan to the balancing value of the pitch angle, it is desirable to have a lower value of the damping coefficient.

 The task is to reduce the deviation from the reference flight altitude and the balancing value of the pitch angle under the action of a disturbance and to reduce the time of the return of the winged wing to the reference altitude and to the balancing value of the pitch angle at the end of the perturbation by generating a non-linear control signal.

где М - некоторый постоянный коэффициент; ϑ- текущее значение угла тангажа.The problem is achieved in that by the method by which the pitch angle, angular velocity and angular acceleration are measured relative to the OZ axis, the formation of control signals proportional to the pitch, the angular velocity relative to the OZ axis and angular acceleration, the summation of the control signals with the subsequent conversion of the received signal into angular displacement of the elevator, additionally form a non-linear control signal. The value of the damping coefficient in a non-linear control signal depends on the sign and value of the pitch angle, sign and value of the angular velocity. Thus, the damping coefficient is variable and its change is carried out according to the law
i $\genfrac{}{}{0ex}{}{\text{*}}{\text{ω}}$ = i _ω (lk) ω _z ,
where i _ω is the calculated value of the damping coefficient in a linear system, ω _z is the angular velocity;

where M is a constant coefficient; ϑ - current pitch angle value.

 The damping coefficient takes its maximum value with increasing pitch angle (pitch angle and angular velocity relative to the transverse axis have the same sign). With the beginning of the return of the pitch angle to the balancing value, the damping coefficient changes stepwise and decreases in proportion to the deviation of the pitch angle from the balancing value. This allows you to prevent large deviations of the flight altitude of the ekranoplan from the reference altitude and pitch angle values from the balancing value, as well as reduce the time of the transition process in height and pitch angle.

 The control device for the longitudinal movement of the winged wing contains a pitch angle sensor, the output of which is connected to the first input of the first adder, an angular velocity sensor, an angular acceleration sensor connected to the third input of the first adder, a steering unit, the input of which is connected to the output of the first adder. In addition, a nonlinear control signal generating unit has been introduced, the first input of which is connected to the output of the pitch angle sensor, the second input is connected to the output of the angular velocity sensor and the output of which is connected to the second input of the first adder, containing the module calculation unit, the amplification unit, and the second multiplication unit with a relay unit, a first multiplication unit, an inverter whose input is connected to the output of the first multiplication unit, the first and second input of which are connected respectively to the outputs of the amplifier unit switch and relay block, the first input of the third multiplication unit is connected to the inverter output, the output of the third multiplication unit is connected to the first input of the second adder, the second input of which is connected to the second input of the third multiplication unit and the second input of the second multiplication unit, which are the second input of the nonlinear control unit signal, the first input of the non-linear control signal generation unit is the input of the module calculation unit, connected to the first input of the second multiplication unit, and the output of the formation unit Non-linear control signal is the output of the second adder.

 The invention is illustrated in figures 1 and 2. Figure 1 presents a block diagram of a device for controlling the longitudinal movement of the winged craft; figure 2 is a block diagram of an implementation of the block forming a nonlinear control signal.

The device contains:
1 - pitch angle sensor;
2 - angular velocity sensor;
3 - angular acceleration sensor;
4 - block forming a nonlinear control signal;
5 - the first adder;
6 - steering unit.

The following notation is accepted:
k _ν ν is the signal taken from the pitch angle sensor 1;
i _ω ω _Z is the signal taken from the angular velocity sensor 2;
k _a a _z - signal taken from the angular acceleration sensor 3;
φ _B is the angle of rotation of the elevator.

 The output of the pitch angle sensor 1 and the output of the angle acceleration sensor 3 are respectively connected to the first and third inputs of the first adder 5. The first and second input of the non-linear control signal generating unit 4 are connected to the outputs of the pitch angle sensor 1 and the angular velocity sensor 2, respectively. The output of the non-linear control signal generating unit 4 is connected to the second input of the first adder 5. The output of the first adder 5 is connected to the input of the steering unit 6.

Block forming a nonlinear control signal (figure 2) contains:
7 - module calculation unit;
8 - gain block;
9 - the first block of multiplication;
10 - the second block of multiplication;
11 - relay block;
12 - the third block of multiplication;
13 - inverter;
14 - second adder.

 The non-linear control signal generating unit comprises a series-connected calculation unit of module 7, a gain unit 8 and a second multiplication unit 10 with a relay unit 11, a first multiplication unit 9, an inverter 13, the input of which is connected to the output of the first multiplication unit 9, the first and second input of which are connected respectively, with the outputs of the amplification unit 8 and the relay unit 11, the first input of the third multiplication unit 12 is connected to the output of the inverter 13, the output of the third multiplication 12 is connected to the first input of the second adder 14, the second input of which is inen with the second input of the third multiplication block 12 and the second input of the second multiplication block 10, which are the second input of the non-linear control signal generating unit 4, the first input of the non-linear control signal generating unit 4 is the input of the computing unit of module 7 connected to the first input of the second multiplying unit 10, and the output of the non-linear control signal generating unit 4 is the output of the second adder 14.

где М - некоторый постоянный коэффициент; ϑ- текущее значение угла тангажа.The operation of the device is as follows. When a perturbation appears, acting on the WZ axis OZ, the angular velocity ω _Z appears. The signal proportional to the angular velocity ω _Z is taken from the output of the sensor 2 and fed to the second input of the non-linear control signal generating unit 4. The disturbance action will also cause the pitch angle to deviate from the balancing value. The signal from the output of the sensor 1, proportional to the deviation of the pitch angle from the balancing value, is fed to the first input of the first adder 5 and to the first input of the non-linear control signal generating unit 4. In the presence of angular acceleration, the sensor 3 generates a signal arriving at the third input of the first adder 5. Block forming a nonlinear control signal 4 generates a signal of the form
i $\genfrac{}{}{0ex}{}{\text{*}}{\text{ω}}$ = i _ω (lk) w _Z ,
i _ω is the calculated value of the damping coefficient in a linear system, ω _Z is the angular velocity

where M is a constant coefficient; ϑ - current pitch angle value.

 The formation of a nonlinear control signal occurs as follows. A signal proportional to the current value of the angular velocity from the second input of the non-linear control signal generating unit 4 is fed to the second input of the second multiplication unit 10, the second input of the third multiplication unit 12 and to the second input of the second adder 14. The signal proportional to the pitch angle is fed to the input of the unit the calculation of module 7 and the first input of the second block of multiplication 10. The calculated module of the current value of the pitch angle from the output of block 7 enters through the amplification block 8 to the first input of the first block of multiplication 9. From the output of the second block As a multiplication of 10, the product of the signals proportional to the current values of the pitch angle and angular velocity is fed to the input of the relay unit 11. The relay unit 11 generates a signal equal to either zero or unit value, depending on the signs of the current values of the pitch angle and angular velocity. From the output of the relay unit 11, the signal is supplied to the second input of the first multiplication unit 9. Depending on the value of the signal at the output of the relay unit 11, the coefficient K at the output of the first multiplication unit 9 takes either a zero value or a value proportional to the current value of the pitch angle. From the output of the first block of multiplication 9 through the inverter 13, the signal is supplied to the first input of the third block of multiplication 12. From the output of the third block of multiplication 12, the signal goes to the first input of the second adder 14. From the output of the second adder 14, the generated control signal is supplied to the second input of the first adder 5.

 At the first adder 5, the control signals coming in with their gains are added. From the output of the first adder, the received signal is fed to the input of the steering unit 6. The steering unit directly acts on the elevator and rejects it in the direction of counteracting external disturbance.

 Thus, the method of controlling the longitudinal movement of the ekranoplane and the device for its implementation reduce the deviation of the ekranoplane from the reference altitude caused by the action of perturbation and reduce the time of return to the reference altitude due to the introduction of nonlinear control of the damping coefficient. This statement is supported by the transient graphs shown in FIG. 3, 5. These graphs were obtained as a result of mathematical modeling of the Ekranoplan - Control System system using a computer. The wave shock and vertical wind are accepted as typical disturbing influences. Figure 3 presents the change in the pitch angle when exposed to a vertical speed of 5 m / s. The number 1 indicates the transient process when using the non-linear control signal generation unit, and the number 2 indicates the transient process with the linear control method. The decrease in the deviation of the pitch angle value from the balancing value is clearly seen in the case of using the non-linear control signal generating unit. When using the non-linear control signal generating unit, the pitch angle deviation from the balancing value is more than halved. With a perturbation in the form of a vertical gust of wind at a speed of 5 m / s, the transient process with respect to the relative flight height when using the non-linear control signal generating unit does not differ significantly from the transient process when using the linear control system. Figure 4 shows the pitch transients under the influence of a disturbance in the form of an angular velocity of 5 deg / s. Angular velocity characterizes the impact of an ekranoplan against a water surface. The number 1 indicates the transient process when using the non-linear control signal generation unit, and the number 2 indicates the transient process with the linear control method. Noticeable is the decrease in the deviation due to the disturbance, as well as the reduction in the return time to angles close to the balancing value when using the non-linear control signal generating unit. Figure 5 shows the transients in relative flight altitude under the influence of a disturbance in the form of an angular velocity of 5 deg / s. The number 1 indicates the transient process when using the non-linear control signal generation unit, and the number 2 indicates the transient process with the linear control method. When using the non-linear control signal generating unit, both the deviation due to the disturbance and the reduction of the return time to the reference flight altitude are reduced.

 The device includes easy-to-implement circuits, consisting of publicly available elements, and is characterized by small overall dimensions and low power consumption.

 This method can be used not only on light winged planes, but also on aircraft when controlling angular movement and flight altitude, where it will also be effective to introduce a block for generating a nonlinear control signal.

Claims (1)

A method of controlling the longitudinal movement of an ekranoplan based on the formation of signals proportional to the pitch angle, angular velocity and angular acceleration, the formation of control signals proportional to the current values of the pitch angle and angular acceleration with their transmission coefficients, the summation of the control signals with the subsequent conversion of the received signal to the steering angle heights, characterized in that a non-linear control signal is formed, depending on the values and signs of the current values of the angle drywall and the angular velocity of the form
i $\genfrac{}{}{0ex}{}{\text{*}}{\text{ω}}$ = i _ω (1-k) ω _z ,
where i _ω is the calculated value of the damping coefficient in a linear system;
ω _z is the angular velocity;

where M is a constant coefficient; ϑ - the current value of the pitch angle.

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