RU2321073C1 - Dynamic multi-level stand - Google Patents

Abstract

FIELD: engineering of training machines, possible use in a complex for semi-natural modeling of flight conditions during training and for training crews of airplanes and helicopters.

SUBSTANCE: the device contains a platform with useful load, hydraulic power supply and hydraulic motors, which change position of the platform in space, each motor having electric control input and consisting of following parts, connected serially: hydraulic cylinder rod position sensor, adder, power amplifier, hydraulic amplifier and power hydraulic cylinder. The rods of hydraulic cylinders in pairs by means of upper joints are connected to the platform, bodies of hydraulic cylinders through lower joints are connected to the foundation. Electric control input is connected to second input of the adder, output of hydraulic power supply is connected to second input of the hydraulic amplifier, and input of hydraulic cylinder rod position sensor is connected to the rod of hydraulic cylinder. Additionally, the device contains following parts, connected serially: block of constants, computing device, frequency characteristics block, and in each hydraulic motor between the adder and power amplifier an adjustable correction unit is installed, first input of which is connected to adder output, second input is connected to the output of constants block which corresponds to current hydraulic motor, the third input is connected to corresponding output of frequency characteristics block, and the output of adjustable correction unit is connected to the input of power amplifier. Additional inputs of computing device are connected to output of rod position sensor of hydraulic cylinder of corresponding hydraulic motor.

EFFECT: increased precision and increased quality of reproduction of control influences by dynamic stand due to increased quality of management of each tracking hydraulic motor during any movements of the platform.

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Description

The invention relates to the field of automatic regulation, and specifically to a control system for multi-stage dynamic stands, comprising several tracking systems, each of which controls one actuator, for example, executive power cylinders that control the single load of a dynamic stand - a vehicle simulator operating in combination semi-natural modeling of flight conditions during trainings and training of vehicle crews, in particular aircraft comrade and helicopters.

Known dynamic stands intended for use in simulators, for example, a dynamic stand KTS TU-204 [1], designed to reproduce acceleration information and containing a platform with a payload (simulator cabin of a simulated vehicle) and controlled by six power hydraulic cylinders, whose rods are paired with the upper hinges are connected to the platform, and the housing using the lower hinges to the foundation.

Each power hydraulic cylinder has a device for measuring the length of its extension and, together with it, a hydraulic booster and an electric control circuit, forms a tracking system controlled by an external reference signal coming from the simulator control system and providing the decomposition of control signals in coordinates corresponding to each power hydraulic cylinder.

, изменяющуюся в зависимости от текущего положения его в пространстве и параметров движения его штока.The qualitative parameters of each hydraulic actuator are determined [2, p. 214], [3] as a function of its constituent components: hydraulic cylinder, hydraulic booster, elements of an electrical control circuit, etc. All of these links have a constant transfer function during operation, and only the hydraulic cylinder has a transfer function

, varying depending on its current position in space and the parameters of its stock movement.

- коэффициент усиления гидроцилиндра,Where

- the gain of the hydraulic cylinder,

p is the Laplace operator,

T _g - hydraulic time constant,

T _m - mechanical time constant.

Therefore, one of the main conditions for the high-quality operation of the complex of tracking hydraulic drives of a dynamic bench is the high quality of regulation, the accuracy and synchronism of their work, which is ensured by the equality of the frequency characteristics of the hydraulic drives and their reactions to control and disturbing influences. This requires not only the equality of transients of hydraulic drives, but also the aperiodic nature of their course with high quality control to exclude the possibility of transients with overshoots and self-oscillations, as well as their excessive duration during jumps of the control action up and down for each hydraulic drive.

The fulfillment of these conditions is complicated by the fact that each hydraulic drive of the dynamic stand is under the influence of significant imbalance due to the weight of the platform and the payload attributable to each power hydraulic cylinder. When simulating the movements of a real object, the imbalance acting on each power hydraulic cylinder constantly changes depending on the angular positions of the platform of the dynamic stand and its linear movements in the horizontal plane.

A significant improvement in the frequency characteristics of servo drives and the alignment of transient parameters during the movement of power hydraulic cylinder rods can be obtained by using corrections for the speed signal, acceleration or error differential in the structure of each hydraulic drive [4]. The greater the transmission coefficients of the feedback loops for speed and acceleration, the smaller the difference in transients. Technical solutions that partially ensure the fulfillment of these conditions are used in the dynamic stand of KTS TU-204 [1]. However, the low quality of regulation and the restrictions imposed by the stability conditions of the drive circuits do not allow providing transmission coefficients of the servo system circuits that would completely equalize the transient processes and give them an aperiodic flow pattern when the power cylinder rods move up and down.

Known dynamic multi-stage stand [5], containing a platform that carries a payload - a rigidly mounted simulator vehicle simulator vehicle, a power source and hydraulic drives that change the position of the platform in space. Each hydraulic actuator has an electric control input and consists of a series-connected sensing element (position sensor of the power hydraulic cylinder rod), an adder, a compensation device for the imbalance acting on the cylinder, a power amplifier, a hydraulic booster and a power hydraulic cylinder. The electrical control input is connected to the second input of the adder, the output of the power source is connected to the second input of the hydraulic booster, and the input of the sensor is connected to the platform. The compensation device for the imbalance acting on the hydraulic cylinder, which is present in the structure of each hydraulic drive and is designed to ensure equality of transients during the movement of the power hydraulic cylinder rod of each hydraulic drive up and down, is made in the form of a computing device and two parallel-connected circuits consisting of a series-connected detector and a controlled amplifier - limiter connected between the adder and the power amplifier, and the control inputs of the controlled amplifiers-ogre ichiteley connected to the output of the calculation unit, whose inputs are connected to outputs of the sensitive elements of servo drives.

With static and small dynamic changes in the moments of load imbalance, the introduction of a compensation device in the structure of each hydraulic actuator provides more substantial compensation than the effect of the imbalance acting on the rod of each power cylinder due to the weight of the platform and the payload, which noticeably evens out the transient processes of the hydraulic actuators.

However, with significant dynamic changes in the moments of load imbalance that occur when simulating the maneuvering movements of real objects, for example, an airplane performing complex maneuvering or aerobatics, it is not possible to ensure an acceptable equality of transient hydraulic drives and the aperiodic nature of their course. This is due to the fact that in the dynamic stand [5] when aligning transients of servo hydraulic drives during their movement in and out of imbalance, only the current positions of the hydraulic cylinder rods are taken into account, without taking into account the magnitude and direction of their velocity and acceleration vectors, and the necessary control quality is not provided.

As a result of this, even with the relative equality of transient processes of servo drives, it is possible to overshoot with self-oscillations, and unreasonably long duration of transient processes. Such movement of the power hydraulic cylinder rods leads either to parasitic “swinging” of the platform, or to large delays in the development of control signals, as a result of the training crew having inadequate sensations that impede the instilling of the correct piloting skills.

The aim of the invention is to increase the accuracy and quality of reproduction by a dynamic stand of control actions by improving the quality of regulation of each servo hydraulic drive, the accuracy and synchronism of their work, i.e. achieving equality of the transfer functions of hydraulic drives, their frequency characteristics and transients with an aperiodic nature of the course with any static and dynamic changes in the unbalanced load on each hydraulic drive for any platform movements.

The essence of the invention lies in the fact that the composition of the dynamic stand, containing the platform with a payload, a power source and hydraulic drives that change the position of the platform in space, each of which has an electrical control input and consists of a series-connected sensor for the position of the rod of the hydraulic cylinder, adder, amplifier power, hydraulic booster and power hydraulic cylinder, moreover, the hydraulic cylinder rods are connected in pairs with the upper hinges to the platform, the hydraulic cylinder bodies are cut the lower hinges are connected to the foundation, the electrical control input is connected to the second input of the adder, the output of the power source is connected to the second input of the hydraulic booster, and the input of the hydraulic cylinder rod position sensor is connected to the hydraulic cylinder rod, an additional block of constants, a computing device, and a block of frequency characteristics are introduced and in each hydraulic drive between the adder and the power amplifier an adjustable correction unit is installed, the first input of which is connected to the output of the adder And the output - to the input of the power amplifier. In each hydraulic drive, the second input of the adjustable correction unit is connected to the output of the block of constants corresponding to the given hydraulic drive, and the third input is connected to the corresponding output of the block of frequency characteristics. Additional inputs of the computing device are connected to the output of the rod position sensor of the hydraulic cylinder of the corresponding hydraulic actuator.

A computing device, as well as a block of constants and a block of frequency characteristics, connected with the possibility of interacting with an adjustable correction unit included in the structure of each hydraulic drive, at each moment of time provide high quality control, damping the "unloaded" hydraulic drive and increasing the quality factor of the "overloaded" hydraulic drive, thereby ensuring the most desired identity of the transfer functions of hydraulic drives, the equality and aperiodic nature of transients, taking into account the effect of acting on each power hydraulic cylinder of imbalance, which varies depending on the current position of the hydraulic cylinder in space, speeds, accelerations of its rod, determined by the combination of changes in the displacements, speeds and accelerations of the rods of all power hydraulic cylinders, taking into account the direction of their movement.

Technical solutions that take into account the change in the load vector for each power cylinder of a dynamic bench, depending on their current relative position, magnitude and direction of the acceleration vectors of each hydraulic cylinder, i.e. no dynamic load on each hydraulic drive and providing high quality of regulation, equality of transfer functions of hydraulic drives, their frequency characteristics and transient processes with aperiodic flow in the patent and scientific literature is not found, which ensures the proposed solution meets the criterion of "inventive step".

The figure 1 shows the structural diagram of a multi-stage dynamic stand;

figure 2 is a kinematic diagram of a multi-stage dynamic stand;

figure 3 - frequency characteristics of an adjustable correction unit for "unloaded" and "overloaded" servo hydraulic drives;

figure 4 - frequency characteristics and the transition process of the adjusted servo hydraulic drives.

The proposed multi-stage (six-stage - figure 1) dynamic stand consists of a platform 1, a hydropower supply 2 and several identical servo hydraulic drives according to the number of power hydraulic cylinders 3, the rods of which are connected in pairs with the upper hinges 4 to the platform 1, and the hydraulic cylinder bodies 3 through lower hinges 5 are attached to the foundation. Each of the following hydraulic actuators consists of a series-connected sensor for the position of the rod of the hydraulic cylinder 6, the adder 7, the power amplifier 8, the hydraulic booster 9 and the power hydraulic cylinder 3.

The dynamic stand includes series-connected block of constants 10, computing device 11 and frequency response block 12. An adjustable correction unit 13 is introduced into the structure of each hydraulic drive between the adder 7 and the power amplifier 8, the first input of which is connected to the output of the adder 7, and the output is connected to the input of the power amplifier 8. The second input of the adjustable correction unit 13 is connected to the output of the block of constants 10 corresponding to the given hydraulic actuator, the third input is connected to the corresponding output of the block of frequency characteristics stick 12. Additional inputs of the computing device 11, by the number of hydraulic cylinders 3, are connected to the corresponding outputs of the position sensors of the rods of the hydraulic cylinders 6.

The dynamic stand works as follows:

When moving the movable platform 1, depending on the current positions in the space of the hydraulic cylinders, the unbalanced load acting on them and the motion parameters of their rods, the transfer function of each hydraulic actuator changes. Moreover, the transfer functions of the adder 7, the power amplifier 8, the hydraulic booster 9, the rod position sensor of the hydraulic cylinder 6, which are part of each hydraulic actuator, do not change when the platform of the dynamic stand is moved in space, only the transfer function of the hydraulic cylinder changes [2, p. 214], [3 ]

or

where k _Hz is the gain of the hydraulic cylinder,

- обобщенная постоянная времени,

- generalized time constant,

- коэффициент затухания,

- attenuation coefficient,

p is the Laplace operator,

T _g - hydraulic time constant,

T _m - mechanical time constant.

T _g = const, because depends on unchanged values - volumetric modulus of elasticity of the working fluid and its volume, etc. [2, p. 200].

where J = ΔmR ² = var is the moment of inertia of the drive link [6];

r = const is the reduced value of the leakage of the working fluid,

k _m = var is the moment coefficient;

Δm = var is the current value of the mass reduced to the rod of the i-th hydraulic cylinder, defined as a function of the reaction of the support R _i ;

R = var is the radius of rotation of the center of mass reduced to the rod of the i-th hydraulic cylinder, defined as a function of the length of the hydraulic cylinder;

When the movable platform 1 is moving, at each moment of time, from the outputs of the constant block 10, the coordinates of the lower hinges 5 and the distances between the upper hinges 4 are received at the corresponding inputs of the computing device 11, and the remaining inputs receive the current values of the signals from the sensors 6 of the position of the hydraulic cylinder rods 3. The computing device 11 calculates the actual position of the hydraulic cylinders 3 (the values of the extension of their rods and the angles of inclination to the horizontal plane) and the position of the movable platform relative to the initial system of ordinates, as well as linear and angular accelerations of the upper hinges 4 and the magnitudes of the reactions of the lower hinges 5. The calculated parameters from the outputs of the computing device 11 go to the inputs of the frequency response block 12, which simulates the available amplitude and phase frequency characteristics of each hydraulic actuator in real time, which the outputs go to the third input of the adjustable correction unit 13 of the corresponding hydraulic actuator, and to the second input of the adjustable correction unit 13 - from the outputs of the block of constants 10 are desired e amplitude-phase frequency characteristics. In the adjustable correction unit 13 of each hydraulic actuator, the parameters of the available and desired amplitude-phase frequency characteristics of the corresponding hydraulic actuator are compared and the parameters (individual for each hydraulic actuator) of the frequency characteristics of the adjustable correction unit 13 are modeled. With increasing load on the rod of the hydraulic cylinder 3, the existing mechanical time constant of the hydraulic cylinder T _mi increases and the forcing effect of the adjustable correction unit 13 begins to prevail to increase the quality factor of the hydraulic actuator; when the load on the rod of the hydraulic cylinder 3 decreases, the value of T _mi decreases and, accordingly, the damping effect begins to prevail; at the optimum value of the load on the rod of the hydraulic cylinder 3, the value of the available mechanical time constant T _mi becomes equal to the value of the desired mechanical time constant T _mj and the adjustable correction unit 13 works as an amplifier with a transmission coefficient equal to 1; in all cases, the quality of the follow-up hydraulic drive remains optimal.

, приложенного к центру масс ЦМ (фиг.2) и представляющего собой геометрическую сумму [7. стр.20]:Thus, in order to compensate for the nonsynchronities, the actual values of the reactions R _i , lower hinges 5, which depend on the magnitude and direction of the total force, are determined in real time

applied to the center of mass of the CM (figure 2) and representing a geometric sum [7. p.20]:

- инерциальная сила,Where

- inertial force

- ускорение, действующее в ЦМ,

- acceleration acting in the CM,

- гравитационная сила тяжести,

- gravitational gravity,

=9,82 м/с² - ускорение свободного падения,

= 9.82 m / s ² - acceleration of gravity,

those,

плоскости GHK коллинеарен вектору

:Because the payload is rigidly fixed on the platform, then their total mass m is located in the center of mass of the CM (figure 2) at a distance r from the geometric center O 'of the platform plane. The origin is located in a plane passing through the centers of the lower hinges 5, the longitudinal OX and transverse OZ axes lie in the same plane, the vertical axis OY in the initial (initial) position of the platform 1 passes through the center of mass of the CM and point O '. So the normal vector

GHK planes are collinear to the vector

:

The kinematic diagram (figure 2) is a spatial system of four connected planes:

- unchanged form of GHK,

- variable shape (due to the change in the length of hydraulic cylinders 3): AGB, CHD, FKE,

where the points G, H, and K denote the centers of the upper hinges 4 with variable coordinates in the OXYZ system, respectively (x _G , y _G , z _G ), (x _H , y _H , z _H ) and (x _K , y _K , z _K ), and the centers of the lower hinges are 5 points A, B, C, D, E, F with constant coordinates, respectively (a _A , b _A , c _A ) ... (a _F , b _F , c _F ).

The current values of the length of the i-th (i = 1 ... 6) hydraulic cylinder 3, i.e. signals from sensors 6 of the position of their rods and constant values of the distances between the centers of the upper hinges 4 L _m uniquely connect the calculated current values of the coordinates of the upper hinges 4:

The numerical solution of equations (6) is performed in a computing device 11, the inputs of which from the corresponding outputs of the constant block 10 receive the coordinates (a _i , b _i , c _i ) of the lower hinges 5 and the distances L _m between the upper hinges 4, and their additional inputs (from the outputs of the respective sensors of the position of the rods of the hydraulic cylinders 6) values s _i .

Further, in the computing device 11, according to the current values of the coordinates of the centers of the upper hinges 4, the equation of the GHK plane is determined in the form of a matrix [8, p. 160]:

and after mathematical transformations of which the plane equation is obtained [8, p. 167]:

xcosα + ycosβ + zcosγ-N = 0

where N is a normal vector - perpendicular to the plane GHK from the origin O '(figure 2),

α, β, and γ are respectively the angles between the normal vector N and the positive directions of the axes OX, OY, and OZ.

и

коллинеарны, следовательно, углы между вектором усилия r и осями OX, OY и OZ также соответственно равны α, β, и γ, исходя из чего, в вычислительном устройстве 11 определяются составляющие нагрузки F_x, F_y, F_z вдоль и моментов М_х, M_y, М_z вокруг ортогональных осей OXYZ, воздействующие на гидроцилиндр 3.In accordance with (5), the vectors

and

collinear, therefore, the angles between the force vector r and the axes OX, OY and OZ are also respectively equal to α, β, and γ, on the basis of which, in the computing device 11, the load components F _x , F _y , F _z along and the moments M _{x are} determined , M _y , M _z around the OXYZ orthogonal axes acting on the hydraulic cylinder 3.

(4) определяется в вычислительном устройстве 11 по соответствующим изменениям положений координат верхних шарниров 4 (х_n, y_n, Z_n) путем вычисления в вычислительном устройстве 11 их вторых производных.Current acceleration value

(4) is determined in the computing device 11 by the corresponding changes in the coordinates of the upper hinges 4 (x _n , y _n , Z _n ) by calculating their second derivatives in the computing device 11.

уравновешивается реакциями R_i нижних шарниров 5 [8], которые направлены вдоль осей гидроцилиндров 3 (фиг.2).An effort

balanced by the reactions R _{i of the} lower hinges 5 [8], which are directed along the axes of the hydraulic cylinders 3 (figure 2).

Six reactions (R _A ... R _F ) of the lower hinges 5, calculated by numerically solving a statically defined problem [7, p. 191]:

the outputs of the computing device 11 are fed to the inputs of the frequency response block 12, where, in accordance with equation (1), the current value of the available mechanical time constant T _mi is determined and the value of the available transfer function W (p) _{u is} modeled.

To bring the resulting transfer functions of each servo hydraulic drive to the desired uniformity, the correction unit 13 is made adjustable and is a link with the transfer function W (p) _to , forming the desired transfer function W (p) _w , the value of which from the output of the block of 10 constants goes to the second the input of the adjustable node 13 correction.

From equation (1) it is seen that, depending on the parameters of the movement of the hydraulic cylinder rod and its position in space, only the existing component changes

,

,

which is corrected to the desired form W (p) _w by sequentially including the corrective link W (p) _k , [9] ie

W (p) _x = W (p) _u W (p) _k ,

hence:

where x (p) is the acting quantity ,

y (p) is the output quantity,

Figure 3 shows, as an example, the experimental frequency characteristics of the correction units implemented in the adjustable nodes 13 for correcting links for the cases of "unloaded" drive (R _i > R _nom ) and "overloaded" drive (R _i <R _nom ), which shows that " the unloaded "drive is somewhat damped, and for the" overloaded "drive its quality factor increases, as a result of which the resulting frequency characteristics in both cases acquire the stable form shown in Fig. 4, and the transition process graph has an aperiodic character ter, identical for all drives, which increases the accuracy of testing the set motion parameters of the movable platform 1, eliminates background (spurious) movements, as a result of which the accuracy and quality of reproduction by the dynamic stand of control actions increases and, accordingly, the training capabilities of the simulator as a whole increase.

Information sources

1. KTS TU-204, Technical Description, PKBM, Penza.

2. Gamynin N.S., Fundamentals of servo hydraulic drive, M., Oborongiz, 1962, pp. 200, 214.

3. Bezbogov A.A., Dubovy L.M., Zobkov P.P., Klyuev B.V., Modern aviation simulators, Part 3., Modeling of the acceleration situation, Edition RVVAIU im. J. Alksnis, Riga, 1988, p. 45.

4. Chuprakov Yu.I., Hydraulic actuator and hydraulic means, M., Engineering, 1979, p. 140.

5. Zhukov A.A., Smirnov B.A., Timakov V.M., Fedorov B.C., patent for invention RU No. 2129305, C1, dated December 27, 1996, IPC G09B / 08, publ. 04/20/1999 g. (Prototype).

6. Kuhling X., Handbook of Physics, Translation from German edited by EM Leikin, ed. 2nd., M., Mir, 1985, p. 96.

7. Dobronravov VV, Nikitin NN, Dvornikov AL, Course in Theoretical Mechanics, ed. 2nd, M., High School, 1968, p. 20, 91.

8. Vygodsky M.Ya., Handbook of Higher Mathematics, M., Science, 1976, pp. 160, 167.

9. Ivashchenko NN, Automatic regulation, M., Engineering, 1978, p. 273.

Claims (1)

A dynamic multi-stage stand containing a platform carrying a payload, a hydropower source and hydraulic actuators, each of which has an electrical control input and consists of series-connected position sensors for the hydraulic cylinder rod, adder, power amplifier, hydraulic booster and power hydraulic cylinder, the hydraulic cylinder rods in pairs using the upper hinges are connected to the platform, hydraulic cylinder bodies are connected to the foundation using lower hinges, the electrical control input is connected to to the input of the totalizer, the output of the hydraulic power source is connected to the second input of the hydraulic booster, and the input of the hydraulic cylinder rod position sensor is connected to the hydraulic cylinder rod, characterized in that a series of constants, a computing device, a block of frequency characteristics are introduced into the dynamic stand, and in each hydraulic drive between an adjustable correction unit is installed in the adder and power amplifier, the first input of which is connected to the output of the adder, the second input is connected to the corresponding hyd drive output constant unit, the third input - with corresponding output of the frequency characteristics of the block, and an output coupled to the input of the power amplifier, wherein the additional inputs of the computing device connected to a respective output shaft position sensor corresponding hydraulic drive cylinder.

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