Load Identification Of Roadheader Cutting Mechanism Based On Inverse Pseudo Excitation Method

The roadheader works under high-speed and heavy-duty conditions,and its good performance is the guarantee of coal mine safety production,and its safety and reliability often depends on the operation of the core components of the equipment.Through the analysis and research on the load test of the roadheader,the dynamic load distribution of the core parts of the roadheader can be accurately and accurately identified,which can provide technical support for its fault prediction and evolution,life expectancy prediction and maintenance strategy.However,the load of the roadheader often can not be directly measured with the measuring equipment,so it is necessary to obtain the load information indirectly through the indirect method.The load identification technology is a very effective means.This paper studies the load identification technology which includes frequency domain method,time domain method and artificial intelligence method.The cutting mechanism of the roadheader is subjected to the random load,but random load identification usually adopts frequency domain method of which the calculation of the inverse virtual excitation method is simple and has the higher precision,so the load of roadheader cutting mechanism is identified by the inverse virtual excitation method in this paper.The inverse virtual excitation method needs to know the inverse matrix of frequency response function of the system.In view of existing ill posed problems of frequency response function inversion,this paper introduces the improved Tikhonov regularization method to improve the recognition effect,solves the regularization parameter by GCV criterion,and uses this method to do the MATLAB simulation by the cantilever beam.It has drawn that the load recognition error can be reduced by 2.3d B.Compared to the previous method,it has an ideal effect in improvement of the accuracy.The feasibility of the method is verified by experiments.Because the response test environment in the mine is complicated,it is difficult to work smoothly and efficiently to test the vibration signal.Therefore,this paper constructs the load test platform of the ground false rock wall,and tests the false rock wall on the well.In order to measure the vibration response of the roadheader cutting mechanism,the sensor layout must be optimized.Based on the modal assurance criterion,this paper builds the fitness function of the sensor,and uses particle swarm optimization algorithm to evaluate the fitness as the criterion for evaluating the combination of sensors,which find out the optimal layout of the sensor,and then the vibration response of the cutting mechanism is measured.In addition,it is necessary to obtain the frequency response function of the roadheader cutting mechanism.In this paper,the frequency response function is obtained by transient analysis in ANSYS.In the finite element model of roadheader cutting mechanism,incentive points are chose to apply load according to the principle of measuring point layout.According to the transient dynamics analysis,the displacement signal of the test point is obtained.Written load and the measuring point displacement in MATLAB,Fourier transform of them respectively,on these grounds the frequency response function of the system is calculated.After obtaining the frequency response function,the generalized inverse matrix is solved by the improved regularization method.Then,using the inverse virtual excitation method,the response power spectrum matrix is established by the measured vibration signal,the virtual response vector is constructed,the virtual excitation vector is calculated and load power spectrum is synthesized.By comparing the load spectrum of the cutting mechanism obtained by the actual measured strain,it is concluded that the proposed method can reduce the load recognition error by 2.23 dB and 1.44 dB in the non-natural frequency band and the natural frequency band,respectively.Therefore,this method can improve the accuracy of load identification and provide a basis for the further research on the mechanical characteristics and the optimization designs of the roadheader.