Ústav automatizace a měřicí techniky

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Comparing the Measurement Methods for Testing the Piezoelectric Ring Element in a Knock Sensor
(IIAV CZECH s.r.o., 2023-07-09) Klusáček, Stanislav; Fialka, Jiří; Havránek, Zdeněk; Skalský, Michal; Beneš, Petr
The paper presents experimental research of the ring PZT ceramics that are used as the active element in knock sensors. The aim is to compare selected methods for determining the material coefficients, the pie-zoelectric charge coefficient d33 of an active toroidal PZT element in particular. In the research, we measured the material coefficients of an active ring PZT element to test some of the property detection approaches. Before being employed, each such ring element has to be checked in terms of its overall quality and functionality. The relevant procedure comprises several predefined stages, in-cluding verification of the geometry and material properties. In this context, the resonant frequency is measured to enable calculation of the effective electromechanical coefficient; the concrete values of the frequency and the coefficient enable us to partially assess the actual quality of the sample. This tech-nique, referred to as the frequency method, nevertheless cannot be used to determine the piezoelectric charge coefficient (d33) in the rings; for such a purpose, one of the direct charge determination techniques is regularly utilized. Advantageously, integrating both approaches generally allows us to characterize the applied piezoelement in a comprehensive manner, i.e., from the perspective of the resonant frequency stability in a ring and in terms of verifying the piezomaterial’s pa-rameters and polarization. The experiment relied on a set of Sonox P502-based rings by CeramTec. In these samples, we tested the resonant frequency stability via an Agilent 4294a impedance analyzer. Subsequently, we measured the rings with a d33 meter to determine the value of the charge on the electrodes that corre-sponds to the force applied to the sample. The entire experiment yields a comprehensive description of the involved methods for evaluating and verifying the quality and applicability of piezoelectric rings be-fore their use in knock sensors.
Utilizability of Navigation2/ROS2 in Highly Automated and Distributed Multi-Robotic Systems for Industrial Facilities
(ELSEVIER, 2022-07-20) Horeličan, Tomáš
The field of mobile robotics is a rapidly evolving space with a constant stream of new advancements. As the available technology matures and new features get accessible for lower prices, the scope of applicability for autonomous mobile robots naturally expands. Apart from simple home appliances, a particular area that currently attracts a surge of transformative research is that of industrial facilities and intelligent factories. A higher emphasis is gradually being placed on autonomous operations, where mobile robots start being suitable complements to human workers. Such an application, however, requires complex mechanisms to be able to handle even simple tasks, such as transferring cargo from one place to another while navigating a changing environment and avoiding dynamic obstacles. Robust localization and navigation solutions utilizing the most effective algorithms are necessary for such long and continuous operations that require a high degree of reliability and low error rates. Robot Operating System (ROS) is a highly flexible open-source framework enjoying wide adoption over the years. Its next-generation implementation (ROS2), together with the Navigation2 project (created as a successor to the original ROS Navigation Stack), provide substantial conceptual enhancements with a strong focus on reliability, security, and performance, promising better compatibility with numerous sensor types, higher modularity, and a more controllable deterministic behavior. This paper will guide the reader through necessary steps to deploy the Navigation2 stack onto an existing custom-built ROS2-operating robotic test-bed platform, serving as a concept for future research.
Robust perception systems for automated, connected, and electrified vehicles: advances from EU project ArchitectECA2030
(Elsevier, 2023-12-13) Recekenzaun, Jakob; Solmaz, Selim; Goelles, Thomas; Hilbert, Marc; Weimer, Daniel; Mayer, Peter; Chromý, Adam; Hentschel, Uwe; Modler, Niels; Toth, Mate; Hennecke, Marcus
The perception supply chain (SC1) of the ArchitectECA2030 project investigates failure modes, fault detection, and residual risk in perception systems of electrified, connected, and automated (ECA) vehicles. This accounts for the needs of a reliable understanding of the surrounding environment. The three demonstrators of SC1, described in this paper, address steps of a typical ECA usage cycle: charge - drive - restart charging. The foreign object detection (FOD) demonstrator improves safety within a wireless charging system. The robust physical sensors demonstrator creates a more robust perception by detecting failures within fused and single sensor data. The position enhancement demonstrator improves vehicle localization in areas with reduced GNSS signal coverage. All demonstrators are linked to the challenges that occur during the ECA vehicle usage cycle
Recursive Variational Inference for Total Least-Squares
(IEEE, 2023-06-26) Friml, Dominik; Václavek, Pavel
This letter analyzes methods for deriving credible intervals to facilitate errors-in-variables identification by expanding on Bayesian total least squares. The credible intervals are approximated employing Laplace and variational approximations of the intractable posterior density function. Three recursive identification algorithms providing an approximation of the credible intervals for inference with the Bingham and the Gaussian priors are proposed. The introduced algorithms are evaluated on numerical experiments, and a practical example of application on battery cell total capacity estimation compared to the state-of-the-art algorithms is presented.
Measurement of thermal depolarization effects in piezoelectric coefficients of soft PZT ceramics via the frequency and direct methods
(Elsevier Ltd., 2016-09-01) Fialka, Jiří; Beneš, Petr; Michlovská, Lenka; Klusáček, Stanislav; Pikula, Stanislav; Dohnal, Přemysl; Havránek, Zdeněk
Depolarization at high temperatures around the Curie point constitutes an important yet difficultly measurable material property of piezoelectric (PZT) ceramics. The common vibrometric technique (d33 meters) is not suitable for the measurement of temperature dependences, and therefore we used the frequency method to perform the desired procedures. The indicator selected to show the depolarization state in the piezoelectric ceramics consisted in the piezoelectric charge coefficient, whose value can be effectively measured via the above-mentioned frequency technique. The accuracy of the method was verified via comparing a d33 meter constructed by the authors (as described in this paper) and also by means of differently sized cylinders of ceramics NCE51, which are designed for longitudinal length modes. Based on the obtained results, we established a measurement methodology to exactly determine the value of the Curie point that corresponded to the phase transition to a cubic crystallographic structure. The experiment also confirmed the applicability of progressively controlled depolarization of PZT ceramics by high temperature in the range of between 350 and 370 °C, and it defined the temperature limits at which there occur irreversible changes of the piezoelectric properties of PZT ceramics. In the measured NCE51 material, the limit for irreversible changes was equal to 95% of the Curie temperature (368 °C).

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