In view of the low accuracy of single signal monitoring for the wear state of vibration drilling bit, a multisignal acquisition system for the wear state of ultrasonic axial vibration drilling bit is built to collect the drilling force, vibration, and acoustic emission signals under three different wear states. The drilling force, vibration and acoustic emission signals of the bit in the drilling process are processed by using wavelet decomposition technology, and the signals are extracted from the wear state of the bit, The wavelet energy coefficient with high state correlation is used as the feature parameter to identify the bit wear state. The feature parameter is trained by the combination of noise assisted LMD method and BP neural network. The experiment of single signal and multisignal fusion monitoring bit wear state is carried out, and the neural network structure is optimized according to the error. The results show that the accuracy of monitoring bit wear with a single signal of drilling force is 83.3%, the accuracy of monitoring bit wear with a single signal of vibration is 91.6%, the accuracy of monitoring bit wear with a single signal of acoustic emission is 91.6%, and the accuracy of monitoring bit wear with multisignal fusion is 95.8%; when the number of network layer is 4, the vibration is monitored with the fusion of force signal, acoustic emission signal, and vibration signal The accuracy of the state of drilling tool is up to 100%. The structure model of neural network is optimized reasonably to improve the recognition rate of bit wear in vibration drilling.
Abstract. The vibration of belt in the process of automobile synchronous belt transmission directly influence transmission smoothness, and produce noise and affect the service life of the belt. In this paper, through the establishment of mathematical model of belt transverse vibration in the process of synchronous belt transmission, solving impact of tension on transverse vibration natural frequency; As the same time, designing a synchronous belt transverse vibration natural frequency measuring device in order to measure the transverse vibration natural frequency when the tension is from 300N to 1000N, so as to verify the mathematical model about impact of tension on transverse vibration natural frequency, provide the foundation for choice of tension in the process of automotive multi-pulley synchronous belt design, and have a certain significance on reducing the noise in the transmission process and prolonging the service life of belt .
Aiming at the problem of standing rehabilitation of lower limb motor dysfunction patient. Firstly, the standing movement process of human body is analyzed. Secondly, the exercise trajectory test and pressure distribution measurement test of healthy human body are studied. Thirdly, the
structure of the lower limb standing rehabilitation training device is designed according to the collected joint trajectory. Finally, the movement control trajectory simulation of the lower limb standing rehabilitation training device is carried out according to the collected regional pressure.
The simulation results of virtual prototype coincide with the test trajectory, which shows that the structure of the designed lower limb standing rehabilitation training device is reasonable, and the hybrid control method of force and position can realize the standing rehabilitation training
for lower limb motor dysfunction patient in the light of the set exercise trajectory.
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