# Conveyor Belt Damage Detection with the Use of a Two-Layer Neural Network
## 1 Introduction  
The life of the conveyor belt depends on many factors collected in the literature [1]--among other things, it depends on the type of material transported, the specificity of the transport point as well as the length and age of the conveyor belt. Figure 1 shows the appearance of a conveyor belt used in mining. This device works continuously, transporting the material from the tail pulley to the head pulley. During the operation of the belt conveyor, the belt is passed through both pulleys, changing the running direction on them. Between the pulleys, along its entire length, the belt is supported by sets of idlers. Above the conveyor belt, there is a feet chute, the arrangement and shape of which guarantees the correct arrangement of the discharged material on the conveyor belt and prevents it from spilling out of the belt area. The material is moved along the belt to the head pulley, where the belt direction changes, and the load is thrown outside the area of the belt conveyor [2].  
The most important and most frequently damaged part of the conveyor is the conveyor belt. It is estimated that its cost is about 60% of the cost of the entire conveyor [3, 4]. Demands for conveyor belts require that the belt be a high-quality product, which in turn translates into its cost. The more important is its diagnosis and quick detection of potential damage when it is possible to remove them because the potential failure of the belt conveyor generates a cost associated not only with its repair, but also associated with  
Figure 1: Diagram of the conveyor.  
forced downtime in transport [3]. Figure 2 shows a diagram of a cross section through a conveyor belt.  
The specificity of NDT (non-destructive testing) assumes that, during the inspection of the tested object (here the conveyor belt), it is not subject to degradation or its structure or properties are not changed. Many researchers around the world have developed many systems for the diagnosis of the core of the conveyor belts [3]. Some of the available methods are designed to diagnose the condition of covers, others can detect damage to the steel core embedded in the rubber[5; 6]. In the era of better possibilities of Industry 4.0 data, it is necessary to install the sensor on the tested object and then collect data and process it.  
One of the methods for non-invasive belt diagnostics is the application of a device which uses the changes in the magnetic field as the belt passes under a measurement bar (installed across the entire width of the belt). Such a device is researched at the Belt Conveying Laboratory, Wroclaw University of Science and Technology (Figure 3) [7; 8].  
The operation of magnetic methods in identifying damage is based on the change in the magnetic field generated by the previously magnetized cords that make up the steel core of the tape. Changes in the magnetic field may be caused by joining successive sections of the tape or by damage to the lines (cut, corrosion, missing lines). As part of this method, a magnetic field with a sufficiently large induction flux is induced in the tested object and magnetic scattering fields are searched for [9].  
Based on the data obtained from the Diagbelt system, analyses were carried out [10; 11; 12] to aid the detection of defects or to select the best set of parameters (belt speed, distance from the head, sensitivity) that should be set before the system starts measurements.  
The data obtained from the Diagbelt can be visualized in a two-dimensional drawing. An example of such a plot is shown in Figure 4.  
Figure 3: The device for non-invasive magnetic diagnostic of the belt.  
Figure 2: Diagram of the cross section through the conveyor belt.