# Evaluation of the Acceleration Vibration Signal for Aggregates of the Horizontal Drilling Stand
## 5 Discussion and Future Work  
Laboratory experimental measurements of the vibration signal of acceleration were carried out at two basic states of the device, namely during the operation of the device at no load and during the operation of the device when drilling andesite rock. Nine operating modes were measured within the adjustable states of the horizontal device. Figure 15: Spectrograms of vibration signals of acceleration ((a)) three aggregates without drill bit—2D view, (**b**) three aggregates without drill bit—2D view, (**c**) three aggregates with drill bit—2D view, (**d**) three aggregates with drill bit—2D view, (**e**) andesite rock disintegration—2D view, (**f**) andesite rock disintegration—3D view). The sources of vibrations in the rotary drilling environment are all aggregates and vibrations arising at the rock-drill bit interface. The very interaction of the drill bit as a tool with the rock is the largest source of vibration. It has negative effects on parts of the machinery. Therefore, identifying sources of vibration is important in minimizing side effects. The process of rock disintegration and vibration generation is also affected by the properties of the drill bit, geomechanical properties of the rock being disintegrated (i.e., abrasiveness, grain size, hardness, strength, detachability), input values of pressure force F (N) and revolutions (rpm). Higher hardness, strength, grain, and other geomechanical properties cause stronger vibrations. It can be stated that the vibrations generated by the device have the following components:  
* vibrations of power units (i.e., motor, water pump, and hydro-generator);
* vibrations caused by contact between the drill bit and the rock;
* vibrations from the set values of pressure force F (N) and revolutions (rpm);
* vibrations due to the abrasiveness of the drilling tool during drilling;
* vibrations from the rinsing water inlet and outlet. The results of the proposed signal processing methods can serve as inputs for recognition, vector quantization, and machine learning methods. In addition, the vibration signal processing in the time domain makes it possible to reliably determine specific characteristics and classify the signal according to the displayed waveform. According to the time changes of the statistical characteristics, the vibrations have the character of a non-harmonic, periodic, quasi-periodic, and random signal. With periodic vibrations, the time waveform of the vibro-diagnostic acceleration variable is repeated. The generated vibrations are given by the superposition of compound and random vibrations. When processing vibration signals, the random component often overlaps a composite signal containing essential diagnostic information, a significant problem in industrial practice. Time analysis is appropriate when there is a dominant vibration source; otherwise, diagnostic information is lost. Such a dominant vibration source is the motor unit on the drilling stand. However, the strong stochastic component of the signal caused by the transmission of vibrations from different areas of the machine complex can prevent the exact localization of the cause of the machine vibrations. The total vibration of the machine is a measure of the energy associated with all the vibrations of the stand. The advantage of diagnosing the machine based on total vibrations is the speed and efficiency of the evaluation. The disadvantages of measuring total vibrations are the possibility of information loss in the noise. Frequency analysis eliminates the disadvantages of analysis in the time domain locates the emerging failures of individual parts of the object. The amplitude spectrum and the power spectrum give the complete frequency analysis. Dominant frequencies can be recognized from spectra and spectrograms. It can be stated that the individual operating modes have common frequencies of 52.73, 149.4, and 439.5 Hz in the lower frequency bands and differently in the middle band 1000-3000 Hz.