Research On Active Absorption Technology Of Wave Maker For Narrowband Spectra

In model experiments in marine engineering and other fields,wave makers are used as important instruments for generating waves,aiming to simulate accurate simulation of waves,and it has a great significance for human beings to study wave generators and to study wave theory.However,comparing with the real marine environment,the laboratory simulates the waves in a closed environment such as a sink or a pool.This has the problem of secondary reflection.That is,the wave plate launches an incident wave,and the incident wave encounters the sink wall or structure.The object reflects,and the reflected wave generates a secondary reflection wave after encountering the wave plate.After multiple reflections,the wave environment has been destroyed.There are not only the target wave but also the interference of multiple reflection waves.The experimental data must be inaccurate.Therefore,it is very important to eliminate the secondary reflection wave.In order to eliminate the influence of the secondary reflection wave between the wave maker and the structure,the wave making machine can generate the compensation wave while generating the target wave to eliminate the secondary reflection wave.This method is called the active absorption technology of the wave machine.This paper first introduces the theory of wave making,active absorption theory,and the historical development of wave machine.It introduces the active absorption control equation of push plate wave machine and pushes it to a single frequency regular wave.The active absorption control equations;due to the multi-frequency nature of irregular waves,the irregular wave absorption control equations cannot be solved in the time domain,so they are selected to analyze them in the frequency domain,and the control equations in the time domain are transformed to control in the frequency domain.The equation corresponds to the frequency-domain transfer function of the wave plate stroke and the wave height in front of the plate in the frequency domain.However,since the analytical solution of the frequency domain transfer function cannot be found,only the numerical solution cannot be used for active absorption control.The traditional method is to use the entire frequency domain optimization calculation method,and the wave frequency is mainly distributed in [0,2] Hz,and in the single spectrum case,according to its main frequency distribution,the spectrum coverage frequency range is smaller,and it basically belongs to the narrow-band spectral range.Full frequency domain optimization calculations are not only complicated but also cumbersome,involving correction of all transfer functions in the frequency domain.And when the water depth changes,you still need to do the same work.Therefore,the filter is used to fit the frequency.The domain under the control equation,instead of implementing active absorption control in the time domain.In this paper,the least mean square adaptive(LMS)algorithm is used to calculate the control parameters,and the LMS algorithm calculates the transfer function's fitting value and the theoretical value.After the error analysis,we get the tap weight with the smallest error,and then import the FIR filter.Device.The effect of the control parameters obtained by this method on the active absorption of two-dimensional water tanks was verified by Simulink model simulation.The results of irregular wave simulation experiments show that this method can absorb secondary reflection waves obviously.This paper aims at active absorption simulation experiment and sets up an experimental platform for active absorption wave maker based on the control of Baumueller.The upper computer is an industrial control computer.The upper computer control software is based on MFC.The lower computer is composed of a Daimler PLC02,and a servo motor.The lower computer control software is developed based on ProprogIII.The project is set up in ProMaster.The communication between the host and the slave is based on EtherCAT communication.For the accuracy of the experiment,it is necessary to debug the built experimental platform.The experimental platform can accurately create the target wave before the absorption experiment can be performed.In addition,in order to improve the efficiency of absorption,the control system is also compensated for delay compensation,smooth filtering,and correction of hydrodynamic transfer functions.Finally,the effectiveness of the algorithm is verified by the experimental platform based on the active absorption algorithm theory of LMS.Experiments show that the active absorption control system based on LMS algorithm has good absorption effect in the narrow spectrum range.