JPH0324340A - Control method for active type dynamic vibration absorber - Google Patents

Abstract

PURPOSE:To prevent an excessive force from being exerted on machineries, when the vibration in a main vibration system is fed back to the control device for an active system dynamic vibration reducer, by reducing the feedback gain in response to the increase in amplitude of an added mass. CONSTITUTION:After detected by an acceleration sensor 14, the vibration of a main vibration system 10 is fed back to a damping controller 18, and a control signal is output, via a multiplier 40 and a displacement controller 20, to a servo valve 22, a hydraulic cylinder 24, and an auxiliary vibration system (added mass) 12 constituting an active system dynamic vibration reducer, so as to damp the vibration. In this case, the amplitude of the added mass 12 is detected by a displacement sensor 26, and a given value C1 is subtracted from the absolute value of the amplitude calculated by a computing element 28, and further thereto a given value C2 is added via a limiter 32, and a smoothing circuit 34, and the feedback gain in the multiplier 40 is decreased by a reciprocal computing element 38 in response to the increase in amplitude of the added mass 12. Thus, an excessive force can be prevented from being exerted on machineries, and even if the vibration increases, operation can be continued.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a method of controlling an active type dynamic vibration absorber for reducing vibration in transportation such as ships, architectural structures such as buildings, mechanical devices, etc. This prevents the active type dynamic vibration absorber from overstroke when a large excitation force is applied to the main vibration system.

[Conventional technology]

Dynamic vibration absorbers have long been known as a method for reducing vibrations, but they are passive systems that operate by receiving vibrations from the object (main vibration system).

Recently, an active method has appeared in which the movement of the additional mass of a dynamic vibration absorber is driven by servo control, and it has been put into practical use, albeit in a small number of cases, from the experimental stage. In the active method, the additional mass is vibrated using some means, such as an electric motor or a hydraulic cylinder. Figure 2 is an example. The main vibration system 10 is vibrated from the floor. This vibration is detected by an acceleration sensor 14 and sent to a controller (vibration damping controller) 18 that controls the vibration. The vibration damping controller 18 sends a command according to the detected vibration to the displacement controller 20, and the displacement controller 20 responds to the servo valve 2.
2 to drive the pressure cylinder 24 through the additional mass 12.
move. When the additional mass 12 is moved with appropriate tings,
Since the reaction force at that time cancels the force applied from the floor to the main vibration system 10, the vibration of the main vibration system 10 can be reduced.

The movement of the additional mass 12 is caused by an additional quality f with respect to the main vibration system 10.
This is performed by a servo control system that controls the displacement of fil2. The displacement of the additional mass 12 is detected by the displacement sensor 26, compared with the command value from the vibration damping controller 18 by the displacement controller 20, and a signal corresponding to the deviation is sent to the servo valve 22 to control the flow of oil to the pressure cylinder 24. The flow is controlled to move the additional material jtl2.

Since the additional mass 12 needs to move in a substantially straight line, a floor, rail, etc. is usually required to support and guide the additional mass 12, and a pinion rack or a piston rod of the hydraulic cylinder 24 is required to transmit the driving force. I need. Since there is a limit to the length of both the rail and the cylinder, the stroke of the movement of the additional mass 12 is restricted.

Generally, an economically optimal stroke is determined according to the expected magnitude of vibration, and it is desirable to design an active type dynamic vibration reducer to satisfy this stroke. because,
In order to have a large stroke so that it can cope with vibrations of a magnitude that rarely occurs, it is necessary to increase the installation space of the dynamic vibration absorber, and increasing the stroke also means that the additional mass 12 is This means that it is driven with a large amount of vibration, and requires a large amount of power.

For the above reasons, it is uneconomical to determine the stroke by taking into account even the case where the object swings with an exceptionally large amplitude, and sometimes it is impossible due to limitations in installation space or driving force.

[Problem to be solved by the invention]

When an active type dynamic vibration absorber with limited stroke or driving force is installed, the following problems will occur if the object vibrates with an exceptionally large amplitude.

Since the active method is controlled by servo control, it attempts to drive the additional mass with a force proportional to the magnitude of the swing of the object. The size of the stroke is also proportional to the size of the runout.

However, if the vibration of the object exceeds the design limit of the dynamic vibration absorber, the electric motor may cause an excessive current to flow or move beyond the stroke limit in order to generate a driving force that exceeds the allowable value. , the additional mass collides with the stopper at the end of the toss stroke.

This will be explained using a simulation example.

Figure 3 shows the vibration of the object when the dynamic vibration absorber is not activated. In this example, since the excitation force is increased or decreased, the amplitude of the object increases accordingly.

FIG. 4 shows the case where the active type dynamic vibration reducer is activated, where (a) shows the movement of the object and (b) shows the movement of the additional mass. In this example, there is no restriction on the stroke of the movement of the additional mass, and it is assumed that it can move by a necessary amount, so the additional mass has an amplitude of 5 scales or more. Since the additional mass can move as much as necessary without being restricted by stroke, the vibration of the object is reduced at a constant rate regardless of the magnitude of the excitation force. On the other hand, in Fig. 5, the strokes that can be freely moved are restricted, and it is impossible to move more than 2.5 scales, so
This is an example in which the movement of the additional mass collides with the stroke end when the vibration of the object becomes thick.

In order for a dynamic vibration absorber to be effective, the motion of the main vibration system and the motion of the additional mass of the dynamic vibration absorber must have a constant phase relationship (move with a phase difference of approximately 90 degrees).

However, if the added mass stops at the end of the stroke and bounces back, the relationship between the main vibration system and the movement of the added mass will be disrupted.
It can no longer be controlled. In Fig. 5, it can be seen that not only is it not possible to prevent vibrations in the main vibration system, but also that severe vibrations are generated due to collisions.

A similar situation occurs when upper and lower limits are set for the output of the drive device. When a certain limit is reached, it suddenly becomes impossible to exert any more force, and the movement of the additional mass becomes disordered. When using a servo valve with hydraulic drive, the opening degree of the servo valve is 1
The same holds true even when the value has reached 00%.

The conventional countermeasure for such cases has been to stop the operation of the dynamic vibration reducer and give up on reducing vibration. Although it is impossible in principle to prevent vibrations that require a capacity that exceeds the stroke or driving force limitations of active type vibration absorbers, even when vibrations that exceed the constraints occur, it is within the range of the dynamic vibration absorber's capabilities. If the vibration of the main vibration system can be reduced even a little within the system and smooth operation can continue, the dynamic vibration absorber can be designed to the minimum size required to withstand the vibrations that are normally expected to occur. It is effective in preventing damage caused by rough operation, and at the same time, vibrations of a magnitude that rarely occur can be reduced within the range of the dynamic vibration absorber's capabilities.

This invention was made in response to these demands, and it prevents the dynamic vibration absorber from overstroke when a large excitation force is applied to the main vibration system, thereby preventing excessive force from being applied to the equipment. The purpose of this invention is to provide a control method for an active type dynamic vibration absorber that prevents this.

[Means to solve the problem]

In this invention, the feedback gain is decreased in accordance with an increase in the amplitude of the additional mass of the dynamic vibration reducer. Further, according to the present invention, the feedback gain is decreased in accordance with an increase in the amplitude of vibration of the main vibration system. Further, according to the present invention, the feedback gain is reduced in accordance with an increase in the power or force of the actuator that drives the additional mass.

[For production]

The movement of the additional mass becomes erratic because it suddenly stops at the end of the stroke or when the speed of the driving force reaches its upper and lower limits, the rate of change in force and speed suddenly drops from a certain value to zero. It is. However, without suddenly setting limits on stroke and driving force,
By gradually approaching the limit, the dynamic vibration reducer can continue to operate without disturbing the phase difference between the motions of the main vibration system and the additional mass, and the vibrations of the main vibration system can be reduced. By the way, in the active type dynamic vibration absorber, the movement of the additional mass is servo-controlled, so the effectiveness of the dynamic vibration absorber can be adjusted by the control gain. If the gain is made smaller, the amplitude of the additional mass becomes smaller, and the required driving force also becomes smaller in proportion. Therefore, if the amplitude of the movement of the dynamic vibration reducer, the amplitude of the main vibration system, or the required driving force increases, the amplitude of the additional mass will be proportional to the amplitude of the main vibration system by decreasing the control gain accordingly. Therefore, the dynamic vibration reducer can be prevented from operating beyond its design limit, and the vibration of the main vibration system can be reduced within the limits of its capacity.

〔Example〕

An embodiment of this invention is shown in FIG. The same reference numerals are used for parts common to the conventional device shown in FIG. 2. This embodiment is configured to reduce the control gain when the amplitude of the added mass exceeds a certain value.

The main vibration system 10 is vibrated from the floor. This vibration is detected by an acceleration sensor 14 and sent to a controller (vibration damping controller) 18 that controls the vibration.

1; I vibration controller 18 sends a command according to the detected vibration to displacement controller 20, and displacement controller 20 drives hydraulic cylinder 24 via servo valve 22 in response to the command to move additional mass 12.

The absolute value of the displacement of the additional mass 12 detected by the displacement sensor 26 is determined by an absolute value calculator 28, a constant value c1 is subtracted from the result by an adder/subtractor 3o, and a negative value is cut by a limiter 32. Values smaller than c1 are ignored.

The result is a full-wave rectified waveform with only the top portion of the wave remaining, as shown in FIG. 6 as the output of the limiter 32. The smoothing circuit 34 is a circuit for smoothing this, and the resultant signal passed through this circuit has a substantially constant magnitude that increases or decreases depending on the magnitude of the additional quality J112. Since 38 is a reciprocal calculation circuit, its output becomes smaller as the amplitude of the added mass becomes larger. The output of the smoothing circuit 34 is given a constant tm by an adder 36.
c2 is added to prevent the human power applied to the reciprocal calculation circuit 38 from falling below a certain value. This prevents the output of the reciprocal calculation circuit 34 from becoming excessive. 40 is a multiplier,
The signal from the vibration damping controller 18 is multiplied by the value from the reciprocal calculator 38. The output of the reciprocal calculator 38 is the additional mass 1
Conversely, when the amplitude of 2 becomes large, it becomes small, so the control gain becomes small.

An example of the operation of the apparatus shown in FIG. 1 is shown in FIG. (a) shows the movement of the main vibration system 10, and (b) shows the movement of the dynamic vibration absorber additional mass 12. . In this example, the control gain is not changed when the amplitude of the additional quality ffil2 is below a certain value, and when it exceeds the certain value, the gain is reduced accordingly.

As can be seen from a comparison with FIGS. 4 and 5, even if the amplitude of the main vibration system 1o becomes large, the amplitude of the additional mass 12 is smaller than in the case of FIG. 4. Moreover, even though the amplitude is made small, no disturbance of movement is observed because the stopper is not forced to stop it as in the case of Fig. 5.

In this way, it can be seen that if the gain reduction method is appropriately adjusted, the vibration of the additional quality ffil2 can be prevented from reaching the stroke limit.

[Example of change]

In the above embodiment, the control gain is increased or decreased in accordance with changes in the amplitude of the added mass with respect to the main vibration system, but changes in other variables, such as acceleration, velocity, or displacement of the main vibration system or the acceleration, speed, or The gain is adjusted according to variables that change in response to the magnitude of the vibration of the main vibration system or the magnitude of the movement of the dynamic vibration reducer, such as the amplitude of pressure fluctuations in the pressure cylinder or the amplitude of the current when using an electric motor. It is clear that similar effects can be obtained even if the values are changed. In either case, for example, use an appropriate variable as an absolute value calculator (see Figure 1).
This can be achieved by using human power.

Further, the embodiment described above shows an example of a means for changing the gain according to the amplitude, which may be implemented by, for example, a program in a control computer, etc., without using a dedicated electronic circuit.
It is clear that other means may be used.

〔Effect of the invention〕

As explained above, according to the present invention, it is possible to continue operation even when vibration becomes large without designing an excessive stroke, so equipment can be installed in a limited space, and equipment can be unnecessarily It is economical because there is no need to increase the scale of the system. Furthermore, it is possible to continue operation when large amplitude vibrations, which would normally require a dynamic vibration reducer, occur in the main vibration system.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing one embodiment of the present invention. FIG. 2 is a block diagram showing a conventional device. FIG. 3 is a diagram showing the vibration state of the object when no dynamic vibration absorber is used. FIG. 4 is a diagram showing the operating state of the conventional device shown in FIG. 2, in which (a) shows the operation of the main vibration system, and (b) shows the operation of the additional mass. FIG. 5 is a diagram showing the operating state of the main vibration system when the additional mass collides with the upper limit of the stroke in the conventional device shown in FIG. FIG. 6 is a waveform diagram of each part of the device of FIG. 1. FIG. 7 is a diagram showing the operating state of the device in FIG. 1, and (a)
(b) is a diagram showing the operation of the main vibration system, and (b) is a diagram showing the operation of the additional mass. 10... Main vibration system, 12... Additional mass, 4o...
Multiplier.

Claims (3)

[Claims] (1) An active type dynamic vibration absorber characterized in that when the vibration of the main vibration system is fed back to the control device of the active type dynamic vibration reducer, the feedback gain is reduced in accordance with the increase in the amplitude of the added mass of the dynamic vibration absorber. How to control a vibration absorber. (2) An active type dynamic vibration absorber characterized in that when the vibration of the main vibration system is fed back to the control device of the active type dynamic vibration absorber, the feedback gain is reduced in accordance with the increase in the amplitude of the vibration of the main vibration system. How to control the device. (3) An active device characterized in that when the vibration of the main vibration system is fed back to the control device of the active type dynamic vibration absorber, the feedback gain is reduced in accordance with an increase in the power or force of the actuator that drives the additional mass. Dynamic vibration absorber control method.