JPH0157206B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a vibration control device for controlling low frequency vibrations of elevated roads and the like.

Generally, an elevated road has a structure in which piers are fixed to foundations buried deep underground, and a bridge is mounted on top of the piers. In an elevated road having such a structure, when a car or the like runs on the bridge, vibrations occur due to resonance in the bridge and the piers. This vibration has become a major social problem as so-called low-frequency vibration pollution that vibrates surrounding buildings via the ground.

[Prior art]

As a countermeasure to this problem, various methods have been used to reduce the vibration of elevated roads, which are sources of vibration, especially bridge piers connected to the ground.

FIG. 1 shows a conventional example of a vibration control device installed on a bridge pier of an elevated road. This figure shows a cross section of an elevated road pier. In the figure, 1 is the support of the pier, 2 is the main beam of the pier, 3 is the bridge, 4 is the foundation of the pier, 5 is the building, 6 is an accelerometer that detects the vibration of the pier support 1, and 7 is the acceleration of the accelerometer 6. An integrator that converts a signal into a speed signal, 8 a power amplifier, 9 an actuator such as a motor, 10 a connecting rod that transmits the force of the actuator 9 toward the pier brace, 11 connects the connecting rod 10 to the pier brace. This is a gusset that connects to the In the vibration control device with the above configuration, when a running load such as a car is applied to the pier as an external force, vibrations as shown by the dotted line occur on the pier, and the vibration acceleration of the pillar 1 is detected by the accelerometer 6 attached to the pillar 1. be done.

This acceleration signal is converted into a velocity by an integrator 7 and then sent to an actuator 9 via a power amplifier 8.

This actuator 9 suppresses the vibration of the pier support 1 by applying a control force proportional to the vibration speed to the connecting rod 10 and acting in the direction of the pier brace in a direction that cancels out the external force. The dotted line in the figure shows an example of a typical vibration mode of a bridge pier; an actual bridge pier has a plurality of vibration modes at close vibration frequencies due to its complex structure.

Generally, a vibration system with multiple vibration modes is
It can be thought of as a superposition of each vibration mode.
Now, when considering the order of the vibration mode of the pier up to the nth order, the equation of motion of the vibration control system is as follows.

q ₁ +2δ ₁ ω ₁ q′ ₁ +ω ² ₁ q ₁ = ( ₁ / m ₁ )・F− (△φ ₁
/m ₁ ) U 〓 q _i +2δ _i ω _i q _i +ω ² _i q _i = ( _i /m _i )・F−(△φ _i /m
_i ) U 〓 q _o +2δ _o ω _o q′ _o +ω ² _o q _o = ( _o /m _o )・F−(△φ _o
/m _o ) U...(1) Here, q _i ; Vibration displacement of the first mode expressed in generalized coordinates q _i ; First time differential value of q _i q _i ; Second time differential value of q _i δ _i ; Damping ratio of the i-th mode ω _i ; Natural frequency m _i of the i-th mode; Mode mass _i of the i-th mode; Size of the eigenmode of the i-th mode at the point of external force application △φ _i ; Control force application point Difference in the magnitude of the eigenmode of the _i -th mode of The detected acceleration x ₁ of 6 is given by the following equation.

x¨ ₁ = _o 〓 ⁱ⁼¹ ( _i・q¨ _i ) …(2) Also, the control force acting on the pier is as follows.

U=C _M・x〓 ₁ …(3) where, C _M : gain constant, x〓 ₁ : speed When considering the control system of the vibration control device, the vibration acceleration detection point of the pier is determined from the control force U of the actuator 9. Frequency characteristics and vibration acceleration up to acceleration x _¨1
The frequency characteristics from x¨1 to control force _U are important factors for control stability and vibration control effectiveness. Here, the frequency characteristics of _the vibration acceleration x¨1 from the control force U are:
It shows the characteristics of _the pier, and the frequency characteristics of the vibration acceleration x¨1 to the control force U show the characteristics of the vibration control device.

From equations (1) and (2), the transfer function Z _s (S) from the control force U to the vibration acceleration x ₁ is given by the following equation.

Z _s (S)=x¨ ₁ (S)/U(S)= _o 〓 〓 ⁱ⁼¹ (△ _i /m _i )・_i・S ² /(S ² +2δ _i ω _i S+ω ₂ / _i
) ...(4) Here, S: Laplace operator U (S): Function obtained by Laplace transform of control force U x ₁ (S); Function obtained by Laplace transform of vibration acceleration x ₁ Also, from vibration acceleration x ₁ Transfer function to control force U
Z _c (S) is expressed as Z _c (S)=U(S)/X ₁ (S)=C _M /S (5) from equation (3).

FIG. 2 shows a control block diagram of the vibration control device. From Fig. 2, the control loop open-loop transfer function Z ₀
(S) is given by the following equation.

Z ₀ (S)=Z _S (S)・Z _C (S)={ _o 〓 〓 ⁱ⁼¹ (△ _i /m _i )・φ _i・S ² / (S ² +2δ _i ω _i S+ω ² / _i
)}・C _M /S…(6) In equation (6), if the polarity of the constant △φ _i・_i is the same for all vibration modes, the phase of Z ₀ (S) changes from +90° to − Because it changes between up to 90°,
It is well known from automatic control theory that even if the gain constant C _M is increased, the control system remains stable and vibration can be controlled effectively.

However, in structures such as bridge piers that have complex vibration modes, the polarity of the constant Δφ _i · _i may not be the same for all vibration modes. This causes a mixture of vibration modes in which vibrations are reduced and vibration modes in which vibrations are excited, which deteriorates the vibration control effect and makes the control system unstable.

FIG. 3 shows an example of measuring the frequency characteristics of equation (6) in the conventional example shown in FIG. FIG. 3 shows the phase characteristics, and in the frequency region higher than frequency _f1 , the phase lags behind −90°. For this reason, f ₁
In a vibration mode in a lower frequency range, vibration is reduced, and in a frequency range higher than f ₁ , on the contrary, vibration increases, resulting in a significant decrease in control performance.

[Summary of the invention]

This invention improves the above-mentioned conventional drawbacks by adding or subtracting the vibration acceleration of the vibration acceleration detection point to be controlled by the vibration acceleration of other detection points, thereby eliminating the unstable phase. An object of the present invention is to provide a vibration control device that is improved and has a wider controllable vibration frequency range.

[Embodiments of the invention]

An embodiment of the vibration control device of the present invention will be described in detail below with reference to the drawings. FIG. 4 shows a vibration control device of the present invention, in which 1 to 11 are the same as the conventional example. 6a is an accelerometer installed at a location where vibration is to be controlled, and 6b is an accelerometer installed at another location. 12 is an adder that adds or subtracts the signals of the accelerometers 6a and 6b.

This invention having the above configuration has an accelerometer 6b
_The measured value of the open-loop transfer function at
Since the phase is within the range of +90° to -90°, when this acceleration signal is added to the acceleration signal of the accelerometer 6a by the adder 12, the phase of the synthesized transfer function is as shown in Fig. 6. Become. In other words, the phase of the signal at the point to be controlled is the frequency f ₁
Although the phase was delayed by more than -90° in the higher frequency range, it is now within -90° even at f ₀ in the vibration control frequency range due to synthesis, and the overall phase is flattened to around 0°, so it is stable. control is possible.

Note that in the above example, the acceleration signal of one other location is added to the acceleration signal of the location to be controlled, but the same effect can be obtained even if multiple signals are added or other signals are subtracted. Needless to say, you can obtain

〔Effect of the invention〕

As explained above, the present invention can flatten the phase over a wide vibration control frequency range by adding or subtracting the acceleration signal of another location to the acceleration signal of the location to be controlled.
A stable vibration control effect can be obtained.

[Brief explanation of drawings]

Fig. 1 is a diagram showing a conventional embodiment, Fig. 2 is a block diagram of a conventional control system, Fig. 3 is a diagram showing an example of phase characteristics of a conventional control system, and Fig. 4 is a diagram showing an example of a conventional control system. FIG. 5 is a diagram showing an example of the phase characteristic at another acceleration detection point of the present invention. FIG. 6 is a diagram showing an example of the phase characteristic of the added signal. , 2 is the main beam of the pier, 3 is the bridge, 6
a, 6b are accelerometers, 7 is an integrator, 8 is a power amplifier, 9 is an actuator, 10 is a connecting rod, 1
1 is a gusset, and 12 is an adder. In addition, in the figures, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims] 1. A means for detecting vibrations at multiple locations of a vibrating body that vibrates under external force from an elevated road, etc., an adder for adding or subtracting detection signals from the multiple locations, and an integrator for integrating the added or subtracted signals. A vibration control device comprising: a power amplifier that flows a current proportional to an integrated signal; and an actuator that receives this current and applies a control force to the vibrating body.