Text written in Basque and translated automatically by Elia without any subsequent editing. SEE ORIGINAL

ORONA-Mondragon University, in elevator research

They have already become indispensable in the buildings. And although it is scary, most of us like to take the elevator in front of the long stairs. These devices have been significantly modified and modernized, but there is still room for improvement. This work is being carried out by the Mondragon Goi Eskola Politeknikoa and the Orona company so that we can walk in the elevators as comfortably as possible.

This mannequin will probably not notice the degree of comfort of the most recent elevators, but it is an indispensable tool to measure it. With microphones placed on both sides of the head, the task of the doll is to collect as faithfully as possible what a person who walks up and down the elevator hears. This is one of the tools used by the researcher Unai Galfarsoro to study the sound quality of elevators. In the past, an empty microphone was used, and decibels were the only parameters used to perform the measurement.

Unai Galfarsoro; Mondragon Unibertsitatea: As mentioned, decibel is traditionally used, but it happens that two sounds can give the same number of decibels but for a person these two sounds can be completely different: one can be more noisy or cause more discomfort, because one has high frequencies or the other low, or one is persistent and the other variable, and in decibels this is not reflected.

Everything is designed so that the resulting sound is as equal as possible to what a traveler would hear: its reflection in the sound in the body is also taken into account. They place an accelerometer on the ground to measure vibrations on the one hand and to identify the phase of travel to which the sound belongs: acceleration, constant speed or deceleration.
Once the sound is recorded, the decibel measurement is analyzed using a metric that goes beyond simple: whether it is low or high, persistent or variable. And then, these data are all interpreted from the perspective of the human factor. The only measure to decide whether a sound is annoying or pleasant is the opinion of people. To do this, they form a jury to measure the recorded sound according to the subjective parameter. The jurors must choose in this case whether they have a favorite sound or another. Finally, subjective judgments and objective metrics are compared to identify the real factors behind people’s perception.

Unai Galfarsoro; Mondragon Unibertsitatea: The conclusion we have drawn after applying the sound quality process in elevators is that this custom model is much more reliable and better correlated with people’s sensation. For example, the correlation provided by the decibel is 66% and the correlation provided by the custom model is about 99%, so they better reflect the effect of noise on people.

That is, if the model predicts that a sound will be annoying to the human ear, it will almost always guess: the subjective factors and the numbers match. Knowing this, the next step is to identify where it comes from and put solutions in place. Engine vibration is one of the most common sources of noise. In this department, they design new machines or electric motors.

The University of Mondragon: The objectives are twofold: to make machines with energy efficiency, high efficiency and good performance, and, on the other hand, from the point of view of vibration and noise, as a source of noise, to make little noise and not introduce much vibration into the mechanical system.

The University of Mondragon: Here we see the structure of a permanent magnet motor, the magnets are what we see in green, around the rotor, and here is the relationship that is fulfilled: the higher the power of the magnets, the smaller and more efficient the motor. What do we understand when we say the power of magnets? Well, the power of the magnet to store energy.

That is why, in this laboratory, they study the properties of the magnets and also the ferromagnetic materials that make up the motor, in search of the most suitable or effective ones. The challenge of size was overcome a long time ago. The machine rooms of the elevators were hidden; the motor and the pulley have been in the same hole for a long time. Now the challenge is different: quieter engines, more compact, with low energy consumption. The key to moving forward on this path is in the materials.

The University of Mondragon: Once the design is done, we build the prototype. This is a prototype of a synchronous machine; see how small it is. What we do here is, on the one hand, measure the efficiency using this high-precision equipment and, on the other hand, we see what vibration the motor generates on the shaft.

The line of research observed and others takes the form of elevators here in Hernani, the research center of Orona.

Alberto Maritxalar; Orona EIC, Head of Research: When we see an elevator from the outside, it seems very simple, but to be really competitive, efficient, ecological, it needs a great technological development and we are always looking to the future to improve these products.

For this purpose, work is carried out in various fields. This is, for example, a safety brake. Here they are measuring how many times the doors close and open without deteriorating. And here, the resistance of the cable is being tested. Cables are a basic element in the improvement of elevators, not only because it hangs from the box itself. Engine vibrations and external noise enter the cabin through the cables. In addition, this excitation is amplified, even increased if the mechanical vibration frequency and the intrinsic frequency of the cable coincide. This phenomenon is called resonance, and this is what is being measured here.

Xabier Arrasate; Mondragon Unibertsitatea: From the point of view of comfort, we can easily see the role of cables with this toy. Let's just imagine that this is a cable, there's a traction sheave up here that pulls, and down there would be the cabin with all the passengers. Then, the element, parameter, characteristic inherent in a cable is its natural frequency; that is, if it vibrates freely, it does not vibrate in any way; it vibrates, so juxtaposed, making such a period every second. What's going on? Some excitation frequencies are generated by the machine Ba. Then, when these excitation frequencies coincide with the intrinsic frequency of the cable, the amplification is very high.

To avoid this annoying conclusion, we first work on the design, and in this mathematical model, with this software, we make a diagnosis of the resonances that could be generated. Once the prototype is built, practical tests are carried out in Orona’s laboratory.

Xabier Arrasate; Mondragon Unibertsitatea: The acceleration is measured, and the force is measured, and then we see in a range of frequencies at which it vibrates in particular. In the end, we identify what these resonant frequencies are, and what we do from a design point of view is, on the one hand, to excite them, and, on the other hand, if it is not possible to attenuate them a little, to attenuate them.