## 2 Data Collection and Preprocessing  
### Data Collection  
In properly designed equipment, failures should be incidental events. For this reason, collecting a sufficiently comprehensive database of elevator cabin door faults can be a long-term process. In addition, most faults depend on the machine's depletion rate and intensity of use. This means that the implementation of the measurement system should first be carried out on older equipment, thus interfering with the already existing system, which is a significant complication. On the other hand, deliberately triggering elevator failures to record their symptoms can lead to accelerated aging of the device's components, as well as cause downtime in normal operation. Therefore, it was decided to build a test stand with the prototype cabin door drive system shown in Figure 2.  
Figure 1: Chronological diagram of the proposed method. At this stage, the question of distinguishing between two types of doors found in elevators needs clarification. The first is the shaft door, which is installed on each floor and is an external element visible to the user. Their main function is to prevent unwanted access to the shaft, mainly in situations when the cabin is in motion or on another floor. Shaft doors do not have their own propulsion system, but only a mechanism that allows them to produce a closing moment when the cabin is outside the landing. This system takes the form of a spring or weight attached in such a way as to cause the door to close automatically. It is worth mentioning that the mechanism also places an additional load on the cabin door drive system (stretching the spring or lifting the weight). Reflecting this system on the test stand is the element marked with the number 6. Access to the inside of the elevator cabin is provided by the cabin door, the only pair which moves along with the elevator cabin and has its own drive using an electric motor. The mechanical coupling between the two types of doors is carried out by a special mechanism 2. This system has guides that move away from each other when the doors are fully closed and locked. When the elevator reaches the corresponding floor, a roller, which is part of the shaft door, enters between the guides. Then, when the door opens, the guides close, tightening the roller and coupling the two mechanisms together. This allows for coordinated movement of the doors and also prevents them from opening at the wrong moment. As already mentioned, simply closing the doors is not sufficient enough to ensure the safety of passengers in a moving cabin. An additional form of protection is provided by locking the door to prevent it from opening. The locking system 3 is also coupled with the guide mechanism of the shaft door connection. The main drive of the cabin door consists of a permanent magnet synchronous motor 5 equipped with an absolute encoder and a controller 8 that simultaneously performs other functions related to the operation of the drive system, such as communication with the main lift module. A toothed pulley has been placed on the shaft of the motor. On the other side of the door mechanism, there is a second pulley on a bearing-supported axle, which during the tests was replaced by a PMSM motor 1 from PERFOPOL, Starachowice, Poland used to simulate bearing failure by introducing an additional load torque depending on the angle of rotation and controlled by controller 10. The actuator that enables the door to move is a toothed drive belt 4. The test bench is also equipped with a measurement system, which consists of temperature sensors LM35 from Texas Instruments, Dallas, TX, USA placed inside the drive motor and under the mount of its controller, a triaxial accelerometer 7 ADXL345 from Analog Devices, Cambridge, MA, USA that allows measurement of vibrations on the door beam, and a microcontroller STM32F302 from ST Microelectronics, Geneva, Switzerland, equipped with 12-bit analog-to-digital converters, for acquisition of measurement data.