SUMMERY OF THE UTILITY MODEL
In order to overcome the amplitude of the output of the hydraulic vibration table under the control of the conventional PID controller under the high frequencyThe value decay can not satisfy this problem of test requirement to the big quality test piece, the utility model provides a variable resonant frequency hydraulic pressure vibration control system based on DSP. The system is based on the system resonance theory, and utilizes the energy exchange relationship between the electromagnetic valve and the hydraulic cylinder to make the vibration table generate larger vibration action in the system resonance mode, i.e. the hydraulic cylinder can generate larger displacement output by giving a signal with small input, and the output can still track the input under the condition that the frequency of the input signal is continuously changed, and the resonance peak value M is given r This multiple increases the peak value of the input signal to meet the test requirements of the hydraulic vibration table for large-mass objects.
In order to achieve the above purpose, the present invention adopts the following technical solution. This system mainly includes hydraulic vibration system 8, wherein, in hydraulic vibration system 8, simulation PID3 and servo valve 4 series connection, constitute the closed circuit of inner ring with displacement sensor 6 again, and digital controller 2 is in proper order again with this inner ring closed circuit, pneumatic cylinder 5 series connection, then constitutes the closed circuit on the outer loop with another displacement sensor 6 again, its characterized in that: the hydraulic vibration control system is characterized by further comprising a DSP control system which is designed based on a resonance theory and used for achieving the function of a resonance controller, the DSP control system inputs a control signal to the input end of the digital controller 2 in the hydraulic vibration system 8, a frequency signal at the output end of the hydraulic vibration system 8 is fed back to the DSP control system through a displacement sensor, an input signal 1 is input to the DSP system through A/D conversion, and an inner ring which is composed of an analog PID3, a servo valve 4 and a displacement sensor 6 is equivalent to an inner ring with the proportion of 1.
The DSP control system realizes the function of a resonance controller based on a resonance theory, and the resonance controller is designed by an automatic control principle:
1) Assuming that Mr is the resonance peak required by the system output, according to resonance theory,
the value of the damping ratio ζ can be obtained, again based on
Can obtain
Wherein, ω is
r Is the frequency of the input signal of the system, and is the transfer function of the whole closed loop system consisting of a DSP control system, a hydraulic vibration system and a displacement sensor
Will be provided with
Substituting transfer function G yields:
namely, the transfer function G and the resonance peak value M are obtained
r And input signal frequency omega
r The relational expression (c) of (c).
2) Because the DSP control system, the hydraulic vibration system 8 and the displacement sensor form a closed loop system, the transfer function of the closed loop system is as follows:
where Gc is the transfer function of the resonant controller, G
0 Is the transfer function of a known hydraulic vibration system;
3) Is composed of
To obtain
Due to G and G
0 It is known to derive the transfer function of the resonant controller from this equation. The variable resonant frequency hydraulic vibration control method based on the DSP is realized according to the following steps:
1) DSP control system transfers the transfer function of the resonance controller
Discretizing into a form of yout1= a 1+ yout _1-a 2+ yout _2+ b1 + u + b2 + u \u1 + b3 + u \u2.
2) The DSP control system compares the frequency of the output signal of the hydraulic cylinder 5 fed back by the displacement sensor with the frequency omega of the system input 1 r The difference e between the two, when e =0, indicates the system outputThe frequency tracking input frequency effect is good, and no processing is performed; when e is not equal to 0, the output of the DSP control system is adjusted to U = U _1+ e, so that a new control signal U is obtained, and the new control signal U is converted into a voltage signal through D/A to control the action of the servo valve 4 in the hydraulic vibration system 8, so as to adjust the displacement output of the hydraulic cylinder 5. This output is then compared with the input signal 1 in the DSP system, as shown in fig. 3, if there is still an error value, the loop calculation is continued to obtain the control signal of the hydraulic vibration system, so as to further control the action of the servo valve 4 and the displacement output of the hydraulic cylinder 5, and the loop is repeated in this way, so as to achieve the real-time tracking effect of the output.
The system is formed by reforming the original hydraulic vibration system 8. Adding a resonance control algorithm G into the outer ring control of the hydraulic vibration system 8 c The output signal of the whole closed-loop control system of the hydraulic vibration table can meet the condition that the peak value of the output signal is M larger than the peak value of the input signal r Performance index of the double. Resonance controller G c About the frequency omega of the input signal r And a damping ratio ζ, which is determined by the amplitude Mr of the desired output of the system, such that, when the system output amplitude Mr is given, the resonant controller Gc is related to the input signal frequency ω r Is composed ofBy counting, i.e. by varying the frequency of the input signal (parameter ω in the algorithm) r The value of (c) so that the output frequency changes to follow changes in the input frequency, i.e., resonant frequency tracking of the system is achieved.
When the system is in operation, the frequency omega of the input signal 1 can be adjusted r And the peak value Mr required to be output by the vibration table is input into the DSP control system, the DSP control system detects the error value between the frequency of the input signal 1 and the frequency of the output signal of the hydraulic cylinder 5, the DSP is used as a main control unit for processing to obtain a new control signal U, and then the control action is exerted on the hydraulic vibration system 8 through a D/A channel. At the moment, whether the waveform output by the hydraulic cylinder 5 meets the requirements of the vibration frequency and the amplitude required by the test piece to be tested or not can be observed by using an oscilloscope, if the amplitude does not meet the amplitude required by the test piece, the resonance controller needs to be resetResonance peak value M r To further increase the output amplitude to achieve the conditions required for the test. The frequency of the input signal is then changed (i.e. the parameter omega in the resonant controller) r ) At the moment, only the discrete control signal corresponding to the resonance controller needs to be changed in the DSP program, and whether the output signal can still be in the resonance peak value M or not within the frequency change range or the maximum frequency position is observed from the oscilloscope r This multiple tracks the input signal. If the test condition is not met, the resonance peak value M needs to be continuously adjusted r And input signal frequency omega r Until the output signal meets the test requirements.
A closed-loop hydraulic vibration control system is formed by using a DSP (digital signal processor) as a controller, a proportional link is adjusted by a servo valve 4 by adopting an inner-loop PID (proportion integration differentiation) control technology, and a control algorithm realized by the DSP is designed to be used as the controller on the basis of a resonance theory, so that a generalized open-loop object formed by the DSP controller and a hydraulic cylinder 5 can be used as a controller at a given frequency of omega r Produces a closed loop resonant peak M of desired amplitude at the frequency of r Realizing the vibration motion of the hydraulic vibration table in a resonance mode and modifying the parameter M in the DSP control algorithm r And ω r The resonance frequency can be varied within the system bandwidth.
Because the traditional PID controlled hydraulic vibration system only can output a tracking input signal of 1. At this time, if the conventional control method is adopted, the displacement output by the hydraulic cylinder 5 cannot meet the test requirement of a large-quality test piece. The utility model adopts the DSP control system to realize the function of the resonance controller,and by using the conversion of the internal energy of the system, the output can still track the frequency of the input signal under the condition of higher frequency, and the amplitude of the output signal can be increased to M of the amplitude of the input signal r Multiple (as can be seen from the results shown in the oscillograph of FIG. 5)) To meet the test requirements of the large-mass test piece; the resonance controller can fully utilize the maximum effective characteristics of elements in the hydraulic vibration system, and meet the frequency and amplitude characteristics of signals required by exciting a large-mass object, so that the vibration action of the vibration table is obtained, and in the algorithm of realizing the resonance controller by using the DSP, the parameter modification is convenient, and the system debugging is easy to realize.
Drawings
The present invention will be further described with reference to the accompanying drawings and examples.
Fig. 1 is a block diagram of a control structure of a hydraulic vibration system.
Fig. 2 is a block diagram of a hydraulic vibration system based on real-time monitoring of a DSP.
Fig. 3 is a flow chart of the hydraulic vibration system under DSP control.
Fig. 4 is an electrical simulation experiment diagram of the hydraulic vibration system.
FIG. 5 is ω r An input/output waveform diagram when = 12.
FIG. 6 is ω r An input/output waveform diagram of = 15.
FIG. 7 is ω r An input/output waveform diagram when = 25.
In the figure: 1. input, 2, a digital controller, 3, an analog PID controller, 4, a servo valve, 5, a hydraulic cylinder, 6, a displacement sensor, 7, output, 8 and a hydraulic vibration system.
Detailed Description
The following describes the embodiments of the present invention in detail with reference to fig. 1 to 4.
The embodiment mainly comprises a hydraulic vibration system 8, wherein the hydraulic vibration system 8 comprises an inner-ring closed loop consisting of an analog PID3, a servo valve 4 and a displacement sensor 6, and the inner-ring closed loop, a digital controller 2, a hydraulic cylinder 5 and another displacement sensor 6 form an outer-ring closed loop. The system is characterized by further comprising a DSP control system which is designed based on a resonance theory and used for realizing the function of a resonance controller, the DSP control system inputs a control signal to the input end of the digital controller 2 in the hydraulic vibration system 8, a frequency signal at the output end of the hydraulic vibration system 8 is fed back to the DSP control system through the displacement sensor and the A/D conversion in sequence, an input signal 1 is input to the DSP system through the A/D conversion, and an inner ring which is composed of the analog PID3, the servo valve 4 and the displacement sensor 6 is equivalent to an inner ring with the proportion of 1.
As shown in fig. 2, the DSP control system of TMSC320C31 is used to implement the calculation of the complex control algorithm of the resonance controller, and the transfer function of the resonance controller is:
wherein G is a transfer function of the whole closed loop system consisting of a DSP control system, a hydraulic vibration system and a displacement sensor
0 Is the transfer function of the hydraulic vibration system of the controlled object. A closed loop formed by an analog PID3 and a
servo valve 4 is equivalent to an inner loop with the proportion of 1 by using a PID algorithm, the frequency of an
input signal 1 of the outer loop is compared with the frequency of a system output displacement signal fed back by a displacement sensor 6, and an error signal e of the two is processed. When e =0, it indicates that the system output frequency has good effect of tracking the input frequency, and does not perform any processing; and when e is not equal to 0, adjusting the output of the DSP control system to U = U _1+ e, namely obtaining a new control signal U, converting the new control signal U into a voltage signal through D/A to control the action of a servo valve in the hydraulic vibration system again, and further adjusting the displacement output of the hydraulic vibration system.
In the embodiment, an analog circuit is built for the hydraulic vibration system 8, and as shown in fig. 4, the electrical simulation system can well simulate the characteristics of the hydraulic vibration system 8 in the system frequency bandwidth range. The hydraulic vibration system represented by a second-order low-pass filter is contained in the electric network model. In the practical application of the hydraulic vibration system, the input signal 1 is generally a sine signal, the working frequency is generally between 0hz and 100hz, and the input signal 1 is transmitted by an A/D converter on the DSPTo the DSP control system 9, the resonance controller will be at a predetermined resonance peak value M r Based on the control algorithm, the parameter omega in the control algorithm is controlled r Dependent on the input signal frequency omega r The change of the control signal is changed, the obtained new control signal is output to a hydraulic cylinder from an analog output port on the DSP (because an inner ring in the hydraulic vibration system is equivalent to a link with the proportion of 1, the whole hydraulic vibration system only plays a role in the link of the hydraulic cylinder), a displacement signal output by the hydraulic cylinder is fed back to the DSP through an analog input port, thereby completing the closed-loop control of the system, and realizing that the output signal is a resonance peak value M of the input signal at a specific frequency point r And (4) doubling.
In fig. 5, 6, and 7, the resonance peak M is set r And =3, in the case of changing the input signal frequency, observing whether the output frequency can change following the change of the input frequency, observing whether the output signal peak value is 3 times of the input signal peak value, realizing resonance control, and meeting the requirement of testing a large-mass object.
In FIG. 5, when ω is r =12 cycle frequency f =12rad/sec =36Hz, and the control function after discretization is as followsThe waveform diagram of the input and output signals of formula (I).
In FIG. 6, when ω is r =15, the resonance frequency f =15rad/sec =45Hz, and the control function after the dispersion is an input/output signal waveform diagram of the following equation.
In FIG. 7, when ω is r =25, resonance frequency f =25rad/sec =75Hz, and the control function after the dispersion is an input/output signal waveform diagram of the following equation. :
when ω is r Beyond 25, i.e. after an input frequency of over 75Hz, the resonance peak will not reach 3, but around 1.5, when ω is r Beyond 50, i.e. beyond 150, the resonance peak will not occur, even if the peak-to-peak value is smaller than the input signal r Upper limit in resonance frequency tracking control of = 3.