RU2249243C2 - Variable rigidity resilient member oscillation damper - Google Patents

Abstract

FIELD: damping of oscillations of resilient members.

SUBSTANCE: damper has resilient member deviation detector, differentiating unit, frequency estimating unit, time parameters calculation unit, control unit, resilient member rigidity regulator and clock pulse oscillator. Current value of speed of change in common coordinate of deviation of resilient member is sent from output of differentiating unit to input of frequency estimation unit. In frequency evaluation unit the evaluations of minimal and maximal frequencies of linearly-damped resilient system are formed at any step of clock pulse oscillator. Those estimations are applied to inputs of time characteristics calculation unit. Values of durations of traffic modes having minimal and maximal rigidity of resilient member are sent from unit for calculating time parameters to inputs of control unit. Info on speed of resilient member is not required.

EFFECT: simplified design.

3 cl, 6 dwg

Description

The invention relates to the field of damping vibrations of elastic structural elements of objects and can be mainly used in the design and creation of promising systems for controlling objects of non-rigid construction.

A device [1] (analog) is known for damping vibrations of an elastic element when passive damping in a system can be neglected. This device implements the law of control of the stiffness of the elastic element in the coordinate-time form:

where q is the phase coordinate of the elastic element; ω _max , ω _min - the maximum and minimum vibration frequencies of the elastic element from the range of possible changes; t is the current time; t ₀ - the most recent point in time at which the deviation of the elastic element vanishes;

- the duration of the driving mode with maximum rigidity during a characteristic half-cycle of oscillations T ₀ = T ₂ + T ₃ ;

- accordingly, the duration of the mode of movement with minimal rigidity during a characteristic half-cycle of oscillations; φ is a constant parameter (angle of logic) with a fixed value of the parameter

Functional diagram of the device [1] is presented in figure 1. The device comprises a control object 1 (elastic element), a sensor 2 for deflecting the elastic element, a control unit 3, and a stiffness controller 4. The control unit 3 contains a zero indicator 5, a key 6, a trigger 7, the first and second delay elements 8 and 9.

The effect of the operation of the device [1] (speed) varies through the values of the parameters T ₂ and T ₃ , which depend on ω _max , x and φ (see (2) and (3)). Given that the last of these parameters, in turn, depends on x, we can conclude that the effect of the use of the device [1] is determined by the frequency characteristics ω _min and ω _{max of the} controlled elastic element.

Using the device [1] involves accurate knowledge of the frequencies ω _min and ω _max through which x, φ (x), as well as T ₃ and T ₂ are calculated. The values of the last two parameters allow you to reasonably choose the characteristics of the delay elements 8 and 9, respectively.

However, it is often impossible (accurately) to accurately determine the parameters ω _min and ω _max for a particular elastic element. The error in the determination of these frequencies can in some cases reach 100% or more. This problem is especially relevant for elastic systems, the design parameters and characteristics of which are capable of changing during the cycle of their application.

In such conditions, it is advisable to use the device [2] (prototype), in which, in the process of oscillations of a real elastic element, based on information about its movement, the frequency parameters are adjusted on each control interval. This device provides the implementation of the optimal control law in the form of feedback [3, 4]:

- фазовая скорость упругого элемента, φ=φ(x) - известная функция.Where

is the phase velocity of the elastic element, φ = φ (x) is a known function.

Functional diagram of the device [2] is presented in figure 2. The device contains a control object 1 (elastic element), a deviation sensor 2 of the elastic element, a differentiating unit 3, an inverter 4, two dividers 5 and 6, an adder 7, two relay elements 8 and 9, an element 10, an element OR NOT 11, an element OR 12, a stiffness regulator 13, a frequency estimation unit 14, a clock pulse generator 15, two quadrants 16 and 18, two division blocks 17 and 22, a functional converter 19 of the dependence of the optimal angle on frequency, a sine 20 and a cosine 21 functional converters. The frequency estimation block 14 comprises an estimation generation block 23 and an averaging block 24.

As shown in [1, 4, 5], laws (1) and (5) as applied to freely oscillating elastic systems are formally equivalent. In this regard, it seems appropriate, using the advantages of the device [2], to implement on its basis control in the coordinate-time form (1), which, in contrast to (5), does not require information about the speed of the elastic element. This simplifies the device [2].

Figure 3 presents the functional diagram of the proposed device, figure 4 is a structural diagram of a unit for calculating time parameters, figure 5 is the same for the control unit, figure 6 is the same for the frequency estimation unit.

A device for soothing the vibrations of an elastic element of variable stiffness (Fig. 3) contains a control object 1 (elastic element), an elastic element deviation sensor 2, a differentiating unit 3, a frequency estimation unit 4, a time parameter calculation unit 5, a control unit 6, a stiffness regulator 7 , 8 clock pulse generator.

Block 5 calculation of time parameters (figure 4) contains the first, second, third, fourth and fifth dividers 9-13, the first and second adders 14 and 15, a quadrator 16, a nonlinear element 17, a constant voltage source 18, a square root calculator 19, tangent computer 20, arc tangent computer 21.

The control unit 6 (Fig. 5) contains a zero indicator 22, a key 23, a trigger 24, the first and second controlled delay lines 25 and 26.

The frequency estimation unit 4 (FIG. 6) comprises an evaluation forming unit 27 and an averaging unit 28.

The evaluation generating unit 27 contains five keys 29-33, four storage elements 34-37, four quadrants 38-41, two adders 42 and 43, a divider 44, a module driver 45, a nonlinear element 46, a two-bit shift register 47.

Block 28 averaging contains six keys 48-53, four adders 54-57, four storage elements 58-61, two dividers 62 and 63, delay element 64, inverter 65, trigger 66, two counters 67 and 68, element And 69.

The proposed device operates as follows.

After the action of an external disturbing moment, the elastic element begins to oscillate with a maximum frequency ω _max , since at rest the rigidity of the elastic element is maximum (from the condition of reducing the amplitude of the vibrations arising from the action of the external disturbing pulse).

The deviation sensor 2 starts to give the current value of the generalized coordinate of the deviation of the elastic element, which is fed to the input of the differentiating unit 3, the first input of the frequency estimation unit 4 and the first input of the control unit 6. In this case, at the output of the control unit 6, a signal is generated and = 0, which is fed to the input of the stiffness regulator 7, providing maximum stiffness of the elastic element, as well as to the sixth input of the frequency estimation unit 4. The current value of the velocity of the generalized coordinate of the deviation of the elastic element is issued from the output of the differentiating block 3 to the second input of the frequency estimation block 4.

и минимальной

частот системы, которые поступают соответственно на второй и первый входы блока 5 расчета временных параметров (см. фиг.4). На первом такте генератора 8 тактовых импульсов в качестве оценок частоты выступают значения

и

. Сигналы

и

образуют входы первого делителя 9, выходной сигнал с которого, пройдя через квадратор 16, представляет собой оценку параметра х_i по формуле (4). Также сигнал

поступает на вторые входы четвертого и пятого делителей 12 и 13 соответственно. Сигнал х_i с выхода квадратора 16 нелинейным элементом 17 преобразуется в значение оптимального угла логики φ=φ(х_i) (аналогично функциональному преобразователю 19 в устройстве-прототипе [2]). Одновременно сигнал х_i преобразуется вычислителем квадратного корня 19 и поступает на первый вход второго делителя 10 и второй вход третьего делителя 11. Значение угла логики φ с выхода нелинейного элемента 17 преобразуется вычислителем тангенса 20 и образует второй вход второго делителя 10. На выходе второго делителя 10 формируется сигнал

который проходит через вычислитель арктангенса 21 и поступает на первый вход второго сумматора 15, на втором входе которого - сигнал π/2, вырабатываемый источником постоянного напряжения 18. На выходе второго сумматора 15 формируется сигнал

и поступает на первый вход третьего делителя 11. С выхода третьего делителя 11 сигнал

поступает на первый вход пятого делителя 13. Выход пятого делителя 13 образует второй выход блока 5 расчета временных параметров, на котором сформирован сигнал T₂ согласно формуле (3). Формируемый источником постоянного напряжения 18 сигнал π/2 поступает также на второй вход первого сумматора 14, на первый вход которого приходит сигнал φ с выхода нелинейного элемента 17. На выходе первого сумматора 14 формируется сигнал π/2-φ, который четвертым делителем 12 преобразуется в сигнал T₃ согласно формуле (2). Выход четвертого делителя 12 образует первый выход блока 5 расчета временных параметров.According to this information, in block 4, the frequency estimates for each clock cycle of the generator 8 clock pulses, starting from the second, the maximum

and minimal

frequencies of the system, which respectively arrive at the second and first inputs of the block 5 for calculating the time parameters (see figure 4). At the first clock cycle of the 8 clock pulse generator, the values

and

. Signals

and

form the inputs of the first divider 9, the output signal from which, passing through the quadrator 16, is an estimate of the parameter x _i according to the formula (4). Also a signal

arrives at the second inputs of the fourth and fifth dividers 12 and 13, respectively. The signal x _i from the output of the quadrator 16 by a nonlinear element 17 is converted to the value of the optimal angle of the logic φ = φ (x _i ) (similar to the functional converter 19 in the prototype device [2]). At the same time, the signal x _{i is} converted by the square root calculator 19 and fed to the first input of the second divider 10 and the second input of the third divider 11. The value of the angle of the logic φ from the output of the nonlinear element 17 is converted by the tangent calculator 20 and forms the second input of the second divider 10. At the output of the second divider 10 signal is generated

which passes through the arctangent computer 21 and enters the first input of the second adder 15, at the second input of which there is a signal π / 2 produced by a constant voltage source 18. A signal is generated at the output of the second adder 15

and goes to the first input of the third divider 11. From the output of the third divider 11, the signal

arrives at the first input of the fifth divider 13. The output of the fifth divider 13 forms the second output of the time parameter calculation unit 5, on which the signal T _{2 is} generated according to formula (3). The signal π / 2 generated by the constant voltage source 18 also arrives at the second input of the first adder 14, the first signal of which receives the signal φ from the output of the nonlinear element 17. The π / 2-φ signal is generated at the output of the first adder 14, which is converted by the fourth divider 12 into signal T ₃ according to formula (2). The output of the fourth divider 12 forms the first output of the block 5 for calculating the time parameters.

The generated signals T ₂ and T ₃ , discretely counted with the pulse repetition rate from the 8 clock pulses generator, respectively, from the second and first outputs of the time parameter calculation unit 5 are supplied to the third and second inputs of the control unit 6 and then to the control inputs of the delay lines 26 and 25 accordingly, to configure their parameters (see figure 5). When the stiffness of the elastic element is set to maximum, the signal u = 0 is generated at the output of the control unit 6 (respectively, at the output of the trigger 24), which opens the key 23 through the inverse control input. At the first change in the sign of the deviation of the elastic element at the first input of the control unit 6, the zero indicator 22 gives a pulse, which through the public key 23 enters the input of the first delay line 25, in which the signal is delayed for a period T ₃ (see (2)). During a time interval of duration T _{3, the} signal u = 0 is guaranteed at the output of trigger 24, which corresponds to the establishment of the maximum stiffness of the elastic element in accordance with the control law (1).

Due to the fact that during the regime of movement of the elastic element with maximum stiffness, multiple retuning of the delay lines 25 and 26 to the current frequency characteristics of the elastic element is carried out, the adaptability of the stiffness control algorithm (1) to change the frequencies of the elastic element is ensured. As soon as the current estimate of the parameter T ₃ is less than the delay already implemented by the delay line 25, the pulse from the output of the first delay line 25 switches the trigger 24 to a single state, due to which the minimum system stiffness is established. In this case, the key 23 is closed and blocks the input information channel. The same impulse, passing through the second delay line 26, after the time interval T ₂ (see (3)) expires, the trigger 24 to the zero state, so that the maximum hardness is set in the system, and the key 23 is opened. The system is again ready to respond to a change in the sign of the deviation of the elastic element as described above. It is significant that in the mode of motion with minimal rigidity, similarly to the regime of motion with maximum rigidity, the adaptability of algorithm (1) to change the frequencies of the elastic element is also provided.

It should be noted, however, that to increase the stability and regularity of switching to maximum stiffness, it is advisable to provide a signal delay in the second delay line 26 slightly less than T ₂ , so that the pulse from the zero indicator 22 has time to pass through the key 23, which opens again trigger signal 24.

и

настройка второй линии задержки 26 в блоке 6 управления запаздывает по отношению к настройке первой линии задержки 25 на некоторое время τ₀. Фактически это означает, что адаптивные свойства предлагаемого устройства реализуются в худшем случае с запаздыванием по времени τ₀. Однако, поскольку характерный полупериод колебаний упругого элемента переменной жесткости T₂+Т₃>>τ₀, влияние запаздывания не сказывается существенно на качестве управления.At the same time, due to the different rates of formation of the signals T ₂ and T ₃ in block 5, the calculation of time parameters with changes in the estimates of the system frequencies

and

the setting of the second delay line 26 in the control unit 6 is delayed with respect to the setting of the first delay line 25 for some time τ ₀ . In fact, this means that the adaptive properties of the proposed device are realized in the worst case with a time delay of τ ₀ . However, since the characteristic half-period of oscillations of an elastic element of variable stiffness is T ₂ + T ₃ >> τ ₀ , the influence of delay does not significantly affect the quality of control.

Sources of information

1. Patent 2192036 of the Russian Federation, G 05 D 19/02, F 16 F 15/00, 2002 (claim 1, analogue).

2. A.S. 1500990 USSR, G 05 B 11 / 01.1987 (prototype).

3. Shalymov S.V., Manuylov Yu.S. Optimal increase in dissipation in an elastic system by controlling its stiffness properties // Methods and algorithms for the study of automatic control systems. Vol. 6. - L .: Ministry of Defense of the USSR, 1988. - P.26-31.

4. Shalymov S.V. Optimal damping of vibrations of simple elastic systems with controlled stiffness. - Ministry of Defense of the Russian Federation, 2001 .-- 101 p.

5. Shalymov S.V. Coordinate-time control of damping oscillations of an elastic system of variable stiffness // Izv. universities. Instrument making. T.46, No. 12, 2003, S.54-59.

Claims (3)

1. A device for calming the vibrations of an elastic element of variable stiffness, comprising an elastic element deviation sensor connected to the output of the elastic element and an elastic element stiffness regulator connected to the input, the output of the elastic element deviation sensor connected to the input of the differentiating unit and the first input of the frequency estimation unit, the output of the differentiating block is connected to the second input of the frequency estimation block, the third, fourth and fifth inputs of the frequency estimation block are connected respectively to the first and second sources of constant voltage and a clock pulse generator, characterized in that it is additionally equipped with a control unit and a time parameter calculation unit, the first and second inputs of which are connected respectively to the first and second outputs of the frequency estimation unit, the first input of the control unit is connected to the output of the deviation sensor of the elastic element, the second and the third inputs of the control unit are connected respectively to the first and second outputs of the time parameter calculation unit, the output of the control unit is connected to the sixth input of the frequency estimation unit and the input of the stiffness controller of the elastic element. 2. The device according to claim 1, characterized in that the block for calculating the time parameters contains five dividers, the first and second adders, a quadrator, a nonlinear element, a constant voltage source, a square root calculator, a tangent calculator, an arctangent calculator, and the first input of the temporary calculation block parameters through series-connected first divider, quadrator, nonlinear element, first adder and fourth divider connected to the first output of the block for calculating time parameters, the output of the quadrator through the serial newly connected square root calculator, second divider, arctangent calculator, second adder, third divider and fifth divider are connected to the second output of the time parameter calculation unit, the second input of which is connected to the second inputs of the first, fourth and fifth dividers, the output of the nonlinear element through the tangent calculator with the second input of the second divider, the output of the square root calculator is connected to the second input of the third divider, a constant voltage source is connected to the second inputs of the first and watts of adders. 3. The device according to claim 1, characterized in that the control unit comprises a zero indicator, a key, a first and second controlled delay line and a trigger, the first input of the control unit through series-connected zero indicator, a key and a first delay line connected to the first input of the trigger whose output is connected to the control input of the key and to the output of the control unit, the output of the first delay line through the second delay line is connected to the second input of the trigger, the second and third inputs of the control unit are connected to the control inputs of the first and second delay lines respectively.

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