# Dimensional Control of Aircraft Transmission Bodies Using CNC Machines and Neuro-Fuzzy Systems
## 3 Research Methodology
### Experimental Studies  
For the construction of neuro-fuzzy models, it is necessary to obtain data from the actual process of manufacturing transmissions. To carry out the experiments and obtain measurement data, a part of the ADT body shown in Figures 5 and 6 was selected. It is the cover subjected to a mechanical machining operation. Figure 4: Accessory drive train (ADT) cover mounted in the machining device. Figure 5: Tested workpiece after the machining operation—top view (machined surfaces visible as lighter). The features of the selected workpiece are as follows:  
* Semi-finished product--sand and mold casting;
* Residual casting stress in the semi-product;
* Technological allowance removed in the operation is up to 3 mm;
* Minimum thickness after processing is 5 mm;
* Deformations of the reference surface after machining operations amount to 0.6 mm. Before the workpiece was machined, the accuracy of the CNC machine was verified using the standard ballbar test according to ISO 230-4 [16]. All geometrical errors were within the manufacturer's tolerances accepted for a new machine. The Renishaw RMP600 (Renishaw plc., New Mills, UK) strain gauge in the machine's equipment was used to measure the workpiece on the machine tool. Before machining, the probe was calibrated using the setting ring and the Renishaw calibration procedure. A test verifying the correctness of the measurement with the datum sphere was carried out for the probe calibrated in this way. This consisted of the following operations: taking the probe from the tool, measuring the height in the Z axis of the machine tool, measuring the sphere diameter with the approach in the X, Y and Z axes, returning the probe to the magazine. The test was repeated 10 times. The maximum measurement error from 10 measurements was 0.3 micrometers. Next, 25 units of covers were machined along with the measurement of selected dimensional characteristics. The process was carried out on an Okuma MU6300V five-axis machining center (OKUMA Corporation, Oguchi-cho, Japan) in an automatic cycle without interfering with the cutting parameters, machine configuration, mounting method or measurement method. The aim of the measurements was to obtain experimental data necessary to build learning and testing sets for the neuro-fuzzy system. After the operation, the accuracy of the machine was verified again. There was no significant change in the value of geometrical errors of the machine tool. All of the values were again within the manufacturer's tolerances accepted for a new machine. The measuring base for cover was determined based on the position of two holes made during the machining operation (hole diameter 6.5 mm, made with a tolerance of +0.015 mm) (Figure 6). In the center of base hole 1, the origin of the coordinate system (point O) was placed, while the center of base hole 2 was used to determine the orientation of the coordinate system. The drawing shows the X and Y axes. The third axis is perpendicular to them and selected in such a way that the XYZ system is clockwise. The measurement program implemented on a CNC machine only applies to the position of the bearing seat under investigation but uses the same measurement methodology as the corresponding fragment of the entire measurement program on CMM. This applies to both the adopted measurement base, the number of measurement points, their distribution and the order of measurements. The reference measurement of the covers was then carried out in the factory CML in accordance with the standard measurement procedure approved in production technology. These dimensional and shape characteristics are a reference point for the new measurement procedure developed. A Mitutoyo CMM with a Revo2 revolution head and Modus 1.7 measuring software was used for the measurement. Figure 6: Base face of the cover (on the circumference) constituting the measuring reference surface—bottom view. In order to clearly interpret the research results, a number of assumptions were made, the most important of which are:  
1.