## 2 Theoretical Background and Calculation  
A simple scheme of the dynamic indentor-rock system, which is affected by two crucial measurable input variables-pressure force F (N) and revolutions n (rpm), is shown in Figure 2[33; 34; 35; 36; 37]. The measurable output of the system is a vibration signal of the acceleration of the drilling rig. All the mentioned variables were recorded as time series characterizing the process of rotary rock drilling [38; 39; 40]. The system also includes \"faults\" that are controllable (e.g., indenter, rock type) or uncontrollable inputs (e.g., geomechanical properties of rocks, flushing water). At present, the drilling rig allows working in the range of the following parameters:  
* pressure force, F (0-15 690) N,
* revolutions, n (0-2400) rpm,
* torque, \(M_{k}\) (0-196) Nm,
* drilled length, \(l\) (0-0.3) m,
* volume flow of water flush, \(Q\) (0-1) \(\times\) 10\({}^{-3}\) m\({}^{3}\)s\({}^{-1}\),
* speed (velocity) of drilling, \(v\) (0-16.8)\(\times\) 10\({}^{-3}\) ms\({}^{-1}\). Figure 2: Scheme of the tool-rock system. A diamond drilling tool's number of revolutions is a basic parameter that increases the drilling speed by good regulation. For small-diameter drilling, the speed reaches a maximum of 2400 (rpm). In surface drilling, it is significantly lower, and they move up to a maximum level of 800 (rpm). Due to the vibrations that occur at higher revolutions with increasing drilling diameter, the speed of revolutions must be reduced from the point of view of the drilling rig's balance work. Therefore, drilling with diamond drilling tools is optimal at higher speeds of revolutions and lower pressure force. The optimal setting of the pressure force is strongly correlated with the revolutions' speed. Obviously, the vibration response of the drilling rig is a random process. Thus, it is necessary to base the analysis and rely on control charts (CC) [41; 42; 43; 44; 45]. The horizontal drilling device consists of a support stand (**12**), on which a headstock (**1**) with a drilling spindle (**2**) is mounted. A drill bit (**4**) of standard size is screwed into the drilling spindle with the core barrel (**3**). The drilling spindle is driven by a DC motor (12.5 kW, 220 V) with external excitation (180 V) via V-belts (**7**). The source of direct current for driving the electric motor is a thyristor rectifier. The flushing fluid is fed from the pump via a rubber pressure hose to the drilling spindle. The rock sample (**5**) is clamped in a mechanical jig (**6**), which is mechanically connected to a strain gauge head of axial pressure force and torque. Parts of the device from the headstock (**1**) through the core barrel (**3**) to the clamping device (**6**) are located in a protective sheet metal housing (**13**). The strain gauge head (ten-so-metric head) is articulated to the piston rods (**8**) of the hydraulic cylinders (**9**). The handle of the sliding ram (**10**) is firmly attached to stand (**12**). The flushing water is drained through a high-pressure hose (**12**) (see Figure 3). The following figures (see Figures 4 and 5) describe and present essential parts of the drilling rig in more detail. Figure 3: Important parts of the drilling rig: **1—**headstock, **2—**spindle drill, **3—**core barrel, **4—**drilling bit, **5—**rock specimen, **6—**clamping mechanism, **7—**belting, **8—**piston of the hydraulic cylinder, **9—**double-acting hydraulic cylinder, **10—**slide, **11—**hose for supply drilling fluid, **12—**stand, **13—**sheet covering. In addition to the measured process variables (revolutions, pressure force) and the vibration signal, the drilled rocks' drilling cores are a practical result of drilling (see Figure 5). Rotary disintegration is carried out on rocks andesite, granite, limestone. The operating modes for the revolutions parameter can be set to \(n=800\) (rpm), \(n=1000\) (rpm), \(n=1200\) (rpm), \(n=1400\) (rpm), and for the pressure force F = 5000 (N), F = 8000 (N), F = 10,000 (N), and F = 12,000 (N).