The present disclosure relates to a device and a method for controlling vibrations. More specifically, a device and a method for controlling vibrations, wherein a circuit is fabricated such that an optimal response signal can be supplied through preceding vibration analysis of a vibrating body, and the response signal is supplied to an actuator when a signal is sensed by a sensor, thereby controlling vibration.
The most effective method for vibration control is to analyze (experiment and simulate) the characteristics of a structure in the design step such that resonance and the transmission of vibrations are suppressed.
Referring to
Dampers are the most widely used vibration reducing devices, and are classified into passive dampers and active dampers.
Referring to
On the other hand, an active damper is generally a device for transmitting a sensed vibration signal to an external control unit (including a frequency analyzer) to analyze the vibration signal, and to generate a response signal capable of suppressing the vibration signal through a signal generator, and to deliver the same to an actuator, thereby alleviating vibration. However, the method of analyzing the vibration signal inside the control unit by using the frequency analyzer has a problem in that an expensive frequency analyzer (which costs at least $10,000) is indispensable, various components (an antenna, a battery, and a cable) are necessary to receive/transmit signals between a bulky external controller, a sensor, and an actuator, and a signal generator needs to be added to supply an appropriate signal.
The frequency analyzer is an effective equipment capable of obtaining accurate values related to vibration, but is expensive, and requires a complicated calculation process. In other words, the signal analysis process alone requires 2-4 seconds (time necessary to convert a time-domain signal into a frequency-domain signal). As a result, a response output is possible after tens of cycles (20-40 cycles when the frequency is 10 Hz) have elapsed following occurrence of vibration. The resulting problem is that real-time vibration control is impossible, and the control efficiency is thus low.
In addition, active dampers may be classified into cases in which vibration analysis is conducted inside an active damping kit and cases in which no vibration analysis is conducted.
In a case according to the prior art in which vibration analysis is conducted inside an active damper, a vibration signal is analyzed through a control box including a frequency analyzer (vibration analysis equipment) inside an active damping kit or another type of measurement equipment, and a vibration wave having an inverse phase is transmitted to a signal generator. The mechanism of an active damping system including a vibration analysis process inside an active damping kit employed by the prior art described above can be summarized as follows: the frequency analyzer analyzes vibration measured by a sensor, thereby obtains a finite number of frequency components, and the signal generator supplies that many responsive signals, with same frequency and opposite phases, to the actuator. The measured vibration signals and the inverse signals generated by the actuator then meet and counterbalance each other, thereby alleviating vibration.
This type of operation mechanism can be summarized into the following four steps as illustrated in
However, if the frequency analysis is conducted inside the active damping kit as described above, a long time is required throughout the entire process of analyzing vibration such that multiple frequency components are accurately analyzed. The resulting problem is that real-time control is impossible, and the expensive frequency analyzer included in the active damping kit increases the price of the active damper.
In addition, when the sensor transmits a signal to the frequency analyzer, the frequency analyzer analyzes the frequency, the amplitude, and the cycle, and then supplies an inverse vibration wave to the signal generator. This process requires wired or wireless transmission/reception and, consequently, additional components such as a wire, an antenna, and a battery are necessary. The volume of the active damping kit is increased because the battery and the antenna are to be installed in the unit. And this makes it difficult to configure a compact and integral active damper.
In a case of the prior art in which no vibration analysis is conducted inside the active damper, the entire signal of a measured vibration signal is inverted so as to respond to the vibration signal. The mechanism of an active damping system including no frequency analysis process inside the active damping kit employed by the prior art, described above, is summarized as follows: a signal from the sensor (1) passes through phase inverters (31, 32) and then drives the actuator (2), thereby controlling vibration of the vibrating body (4).
However, this technology requires that the actuator must be attached to the vibrating body because the response signal needs to move opposite to the vibration so as to respond to the entire signal of the vibrating body.
When this scheme is employed, the frequency of the actuator operation has to be identical to the natural frequency of the vibrating body. Because the response signal is supposed to be the opposite signal of the vibration signal. Accordingly, resonance occurs between the frequencies of actuator and the vibrating body. In addition, there is a very high possibility that the responding signal has noise and errors in the process of generating a signal corresponding to the vibration of a complicated signal having an infinite number of frequency components. In general, the more complicated the signal is, the longer time is required to process the signal. As a result, when the vibration signal is complicated, the delay time increases, making accurate real-time control difficult.
The influence of the delay time, which occurs in the process of analyzing and processing (sensing, reversing, transmitting) a vibration signal and supplying an inverse signal to a vibrating body by an actuator of an active damper system, is described in
Meanwhile, another problem occurring when responding to the entire vibration signal will be described.
Referring to
If a low-pass filter (LPF) is used to reduce such noises, a phenomenon as illustrated in
Referring to
However, a magnified view of the signals shows that, although the noise component of the PCB signal is partially removed, delay time (about 50 ms, half cycle in the case of 10 Hz signal) will occur as a result of passing through the LPF. In addition, if a response signal is supplied later, it is possible that the same will be supplied in the same direction as the original vibration signal due to the delay time. As a result, vibration magnification may occur.
Accordingly, there is the need for a scheme for overcoming the problem of high price, the problem of difficult real-time control (delay time), the problem of the bulky size (because of an actuator integrally attached to the vibrating body), and the problem of having to respond to the entire vibration signal (error occurrence, resonance and delay time).
An aspect of the present disclosure is to provide a device and a method for controlling vibrations, wherein a circuit is fabricated such that an optimal response signal can be supplied through preceding vibration analysis of a vibrating body, and the response signal is supplied to an actuator when a signal is sensed by a sensor, thereby controlling vibrations.
A vibration control device according to the present disclosure preferably includes: a sensor configured to sense vibrations from a vibrating body and to transmit a signal; a control unit (PCB or FPCB) configured to deliver a response signal that counterbalances the vibration signal; and an actuator driven in response to the delivered signal, wherein the control unit is configured in advance so as to supply the response signal acquired through a preceding vibration analysis.
The control unit may include: an input unit configured to receive an transmitted vibration signal; a response signal activation unit configured to activate a counterbalance signal based upon preceding vibration analysis reacting to the vibration signal; and an output unit configured to deliver the response signal to the actuator. That is, the response methods to react to specific vibration with regard to each frequency component, to the magnitude of the response signal, to the cycle of the vibration signal, and thereby deciding the supply time of the response signal, the degree of amplitude attenuation. Also the information regarding whether or not filtering, is determined from the preceding vibration analysis.
The vibration control device may further include a electric current output adjusting device configured to adjust the amount of driving current of the actuator.
Meanwhile, the response signal may respond to the entire vibration signal. Preferably, the actuator is included in an integrated active damping kit, and a passive damper can be installed between a plate member included in the integrated active damping kit and the actuator.
The response signal activation unit preferably supplies the response signal only reacting to a configured number of frequency components among infinite number of frequency components. The configured number of frequency components may be configured in the range of 1 to N, wherein N is a natural number equal to or larger than 2.
The response signal activation unit may supply the response signal with regard to only a (+) direction signal or a (−) direction signal of the vibration signal to avoid attaching actuator unit to the vibrating body which may cause resonances.
In addition, the response signal activation unit may supply the response signal with regard to only a partial cycle of the vibration signal. The partial cycle is 1/N cycle, wherein N is a positive integer.
Multiple actuators may be installed to correspond to the number of vibration directions of the vibrating body. That is, in the case of a vibrating body rotating in multiple directions, such as a rotating shaft, multiple actuators may be used to control vibration. The actuator and the vibrating body are preferably installed separately. The actuator may be coupled to a fixing jig that is fixed somewhere other than the vibrating body.
Meanwhile, a vibration control method according to the present disclosure is characterized in that, while a response signal activation unit is preferably designed (programmed) in advance to supply a response signal acquired through a preceding vibration analysis, the response signal activation unit delivers the response signal to an actuator in response to an transmitted a vibration signal. The designed(programmed) element may include method of reacting to, selecting the number of response signals with regard to all frequency components, deciding the magnitude of the response signal, the cycle of the response signal, the supply time of the response signal, the degree of amplitude attenuation, and the conduction of filtering.
Meanwhile, the response signal may be responding to the entire vibration signal.
The response signal activation unit may supply the response signal only to a configured number of frequency component vibration signals in the order of the largest amplitude among an infinite number of frequency components vibration signals. The number of frequency components may be configured in the range of 1 to N, wherein N is a natural number equal to or larger than 2.
The response signal activation unit may supply the response signal with regard to only a (+) direction signal or a (−) direction signal of the vibration signal.
In addition, the response signal activation unit may supply the response signal with regard to only a partial cycle of the vibration signal. The partial cycle is 1/N cycle, wherein N is a positive integer.
The actuator preferably counterbalances vibration in multiple directions according to the vibration direction of the vibrating body.
As described above, according to the device and method for controlling vibration according to the present disclosure, there is no need to install a frequency analyzer (vibration analysis equipment) in the active damping kit since preceding vibration analysis is conducted. And it is possible to configure an active damping kit that is small sized and inexpensive. In addition, since no signal analysis is conducted inside the active damping kit, real-time response to vibration is possible.
Furthermore, since preceding vibration analysis is conducted, it is possible to configure the active damper's response signal, including the damper installation position, the response signal magnitude, the frequency, the supply time (½ or ¼ cycle), and the number of supplies, so as to conform to the vibrating body. Accordingly, can be optimized and applied to various environments.
In addition, preceding vibration analysis is conducted so as to respond only to a finite number of frequency components having the largest vibration magnitudes. Accordingly, the circuit/actuator configuration and operation can be simplified, the control accuracy and efficiency can be improved, and the error/delay time can be suppressed. That is, the signal process is simple, and the error/delay time is reduced during the processing process, thereby enabling an accurate response in real time.
Meanwhile, by separating the actuator from the vibrating body and designing such that vibration is isolated between the actuator driving unit and the active damping kit, the possibility of resonance can be prevented, thereby enabling effective vibration control.
Prior to designing a vibration control device (active damper), a preceding vibration analysis is conducted to analyze the vibration of a vibration control target (vibrating body) so as to identify the vibration characteristics (frequency, vibration magnitude, cycle, vibration dissipation tendency, and the like), and the control unit is designed(programmed) in advance such that a response signal optimized for the vibration control is supplied. There is no need to install an expensive frequency analyzer in the active damping kit, since preceding vibration analysis is conducted. And it is possible to configure an active damping kit that is small sized and inexpensive.
On the other hand, it is possible to employ, as a vibration suppressing method, a scheme of using a signal sensed by a sensor and directly transmitting the same, or a method of controlling vibration in response to only one direction ((+) direction or (−) direction) or to only ½ cycle or ¼ cycle of the signal, so as to conform to vibration characteristics of a structure. Both methods are preceded by vibration analysis, thereby no analyzing of vibration inside the kit, and naturally real time vibration control is thus possible.
An example of implementation of a device and a method for controlling vibration according to the present disclosure will now be described with reference to specific embodiments.
Referring to
The control unit 200 is designed (programmed) in advance so as to deliver an effective response signal acquired through preceding vibration analysis of the vibration, and the vibration magnitude acquired by the sensor.
Meanwhile, although the actuator 300 is illustrated as being coupled to the vibrating body in the present embodiment, the actuator 300 may be installed separately from the vibrating body.
Referring to
As a result, the control unit does not require the frequency analysis, and thus can be fabricated at a low cost. In addition, the control unit 200 can be simplified so as to respond only to a finite number (1-3) of frequency components such that not only can the circuit be fabricated easily, but a real-time response is also possible because of no vibration analysis inside unit. Furthermore, since the time necessary for the actuator 300 to respond can be designed and limited in advance, and since it is unnecessary to supply a signal responding to the entire signal, the possibility of resonance can be excluded. Moreover, since the control unit 200 conducts simple signal processing, noise occurrence, signal processing time, actuator response time, and the like can be minimized.
Referring to
The control unit 200 may further include a electric current output adjusting device 4 for adjusting the amount of actuator driving current.
The control unit 200 according to the present disclosure, configured as above, receives/delivers signals inside the vibration control device (active damper), and plays the role of an interface between the sensor 100 and the actuator 300. That is, if the sensor 100 senses a vibration signal, the response signal activation unit 2 generates a response signal and delivers the same to the actuator 300.
Meanwhile, the vibration occurring in the second step of
Referring to
Meanwhile, the types of vibrations can be generally classified into vibration resulting from impacts (inter-floor noise, snoring, vibration resulting from an instantaneous acceleration/deceleration), harmonic vibration (vibration resulting from centrifugal force from a rotating body such as a motor, shaft), and random vibration (earthquake). A method for suppressing vibrations in response to each mode of vibration will now be described.
Referring to
Meanwhile, there may be another vibration control method wherein a response is made only to signals in one direction ((+) direction signals or (−) direction signals).
The magnitude of vibration is sensed such that the actuator 300 operates only a predetermined number of times. This is because, in case of impulse vibration, vibration is transient after the initial vibration response, and thus there is no need to respond thereto.
In this case, the vibrating body and the actuator 300 are preferably spaced apart from each other so as to prevent any possibility of resonance that may occur in the vibration control method described above with reference to
There may be another vibration control method wherein a response is made only at a partial cycle of a vibration cycle.
Referring to
By responding only to ½ cycle or ¼ cycle, and supplying signals for a predetermined period of time (or number of times) only in this manner, vibration can be controlled with no possibility of resonance. All of the four methods described above are preceded by vibration analysis such that vibration can be controlled effectively by supplying an optimal response signal in real time. As a result of fabricating an active damping kit based on preceding vibration analysis. Although it is assumed in the description of the present embodiment that a response is made to ½ cycle or ¼ cycle only, it is also possible to respond to a cycle of 1/N (wherein N is a positive integer).
In
Meanwhile, a method for suppressing vibration in response to harmonic vibration (cyclic vibration, vibration of a rotating body, or vibration resulting from centrifugal force of a rotating body such as a motor, shaft), will be described.
Referring to
Harmonic vibration also has multiple frequency components and occurs repeatedly. In the present embodiment, four exemplary frequency components are illustrated in connection with harmonic vibration signal.
Meanwhile, in order to dissipate vibration, in the case of a rotating body such as a shaft, a response signal may be supplied at multiple locations (see
Finally, a method for suppressing vibration in response to random vibration will be described.
Referring to
Since random vibration is very complicated and irregular, it is not effective to employ the method used to respond to the impulse vibration and the harmonic vibration, which have predetermined patterns. Accordingly, in such a case, a response to vibration having (+) direction signal and (−) direction signal is made in such a manner that, by installing active dampers on both vibrating-direction sides of the vibrating body, response signals are supplied from both sides. In case of earthquakes affecting buildings, for example, most buildings have at least four walls (outer walls) such that at least 70% of building earthquake can be dissipated if respective actuators 300 respond on four walls only. It is unnecessary to install actuators 300 at many locations inside buildings because buildings in general vibrate in predetermined modes depending on the characteristics of the building themselves. Therefore, at least 80% of the entire vibration can be controlled by dissipating vibration having the largest amplitude on the basis of preceding vibration analysis.
As mentioned above, in the case of a damper (see
On the other hand, in the case of a conventional damper (see
Most transient responses of mechanical structures, such as pipes, robots, or inter-floor noise result from impulses.
Therefore, the active damper is preferably designed after identifying such a location at which large vibration occurs, the magnitude, and the mode shape through vibration analysis such that the vibration can be controlled effectively.
Referring to
The completed integrated active damping kit 10 may be installed to be coupled to the vibrating body or to be separated therefrom.
When the integrated active damping kit 10 is installed to be coupled to the vibrating body, a passive damper for vibration isolation may be installed between the damping unit (actuator 300) and the plate member isolation, thereby suppressing transfer of vibration from the actuator 300 to the vibrating body, and preventing resonance.
When the integrated active damping kit 10 is installed to be separated from the vibrating body, at least one integrated active damping kit 10 is installed so as to respond to the vibration direction with fixing jig 20. The fixing jig 20 is preferably fixed in an area other than the vibrating body.
According to the present disclosure, firstly, a damper is designed to respond only to a finite number of modes having the largest vibration magnitudes based on preceding the vibration analysis. By preceding the vibration analysis, it is possible not only to fabricate the damping kit without frequency analyzer (vibration analysis equipment). But to reduce delay time, noise, and errors occurring in the process of responding to complicated signals; secondly, there is no need to install actuators 300 at multiple locations in order to respond to complicated modes; and, thirdly, the possibility of resonance can be removed by designing such that the actuator 300 is separated from the vibrating body, and vibration is isolated between the actuator driving portion and the active damping kit.
Number | Date | Country | Kind |
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10-2017-0020848 | Feb 2017 | KR | national |
Filing Document | Filing Date | Country | Kind |
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PCT/KR2018/001912 | 2/14/2018 | WO | 00 |