# Artificial Neural Network Framework for Hybrid Control and Monitoring in Turning Operations
## 2 Materials and Methods
### Experimental Setup  
A typical complete lathe working process includes machine start-up, standby, spindle start-up, no-load operation, cutting material, no-load operation, spindle stop, standby, and machine shut down [14]. The most predominant part is taken by no-load operation and cutting material times (Figure 2). Therefore, in our dataset we will consider and train our models with values from these 2 cases: no-load operation with different spindle speeds with force F = 0 and cutting material with specific load force F corresponding to a specific spindle speed n.  
To validate the proposed artificial neural network framework for hybrid control and monitoring in turning operations, an experimental dataset was acquired under controlled conditions. Instead of cutting a specific material, a custom braking device was employed to apply variable force loads to the spindle while operating at different spindle speeds. This setup effectively simulated cutting force variations, allowing for a systematic analysis of energy consumption patterns under different machining conditions. For each experimental run, a predefined force, as a result of a radial force R [daN], was applied to the spindle at a specified speed n [rpm] and was measured with non-contact Digital Tachometer code 9221-999A. Corresponding electrical parameters, including power consumption P [kW] and current I [A], were recorded. This approach ensured that the dataset captured a diverse range of force-load interactions, making it representative of real-world cutting conditions while maintaining a controlled and repeatable testing environment. The experimental tests were conducted in the laboratories of the National University of Science and Technology Politehnica Bucharest. The tests were carried out with a universal lathe. The SNA 500 \(\times\) 1500 normal lathe is a medium-sized machine tool manufactured by Uzina de Strunguri Arad with a maximum machining diameter over guides of 500 mm, and the power for driving the main movement is 10 kW. Other characteristics that can be mentioned are the number of main spindle speed steps: 24; the speed range: 16-1600 rpm; the voltage: 380 V; the control voltage: 110 V; and the main fuse: 35 A. The loading of the main shaft of the machine tool was carried out with the help of a custom braking device [15] which behaves as a dynamometric device that allows the application of a radial force R [daN] that causes the appearance of a tangential force F [daN] in the contact area between the loading element and a test specimen on the main shaft of the machine tool. The research was carried out under the following conditions: the outer diameter of the test piece (233 mm) was clamped in the main shaft of the machine tool and external stress with three-way radial force was applied simultaneously using a worm gear. During the experiments, no liquid was used to reduce the temperature. Through symmetrical distribution, the load on the main shaft of the machine tool was uniform, thus avoiding the occurrence of vibrations, according to Figure 3.  
The measurement was based mainly on three sensors, each being in contact with the test piece fixed in the lathe device. Each sensor consists of body 2, attached through plate 1. The application of force, on the test piece, is carried out through body 5, fixed in the channel of disc 4. The deformations of the elastic element in the radial (loading) and tangential (braking) directions are determined, respectively, and attached to the body through the supports 7 and 9. To reduce the vibrations, each sensor is provided with a damping element, fixed between sleeve 3 and an elastic element. The total radial and tangential force are equal to the sum of the corresponding component forces \(\overline{R}=\overline{R_{1}}+\overline{R_{2}}+\overline{R_{3}}\) and \(\overline{F}=\overline{F_{1}}+\overline{F_{2}}+\overline{F_{3}}\), respectively. Figure 2: A complete CNC lathe working process. The loading device (Figure 4) is mounted on the guides of the machine tool.