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1
Content available The MEMS-based barometric altimeter inaccuracy and drift phenomenon
Matyja Tomasz, Kubik Andrzej, Stanik Zbigniew
Zeszyty Naukowe. Transport / Politechnika Śląska
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2022
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z. 116
141--162
EN
MEMS technology has made sensors for measuring barometric pressure and altitude above sea level very cheap and widely used in many consumer electronic devices. This paper presents a theoretical analysis of the sources and types of errors in the barometric altimeter using the standard atmosphere model (ISA). Methods for correcting principal errors caused by non-standard sea level conditions are described and compared. A method of correcting errors in the case of altimeter horizontal movement to the air column and total pressure measurement was proposed. It was compared with another method known from the literature. In the numerical experiment, data recorded by a bicycle computer equipped with a MEMS-based barometric altimeter was analyzed. As the GPS data of the route covered was also known, it was possible to compare the recorded altimeter data with the heights determined from the digital terrain model (DTM), which in this case were considered accurate. The error of the measured altitude calculated in this way was tried to be divided into the principal error, the external error caused by the sensor movement, and the barometer drift. Hence, a numerical experiment was carried out in which, based on the recorded data, an attempt was made to reconstruct non-standard sea level conditions and the impact of speed on the sensor measurements. Furthermore, a method of solving such a reverse problem was proposed. The results of the presented studies can be used in the design of systems correcting the indications of barometric altimeters. The accuracy of the altitude measurement is especially important for small controlled flying objects (UAH) and when recording the route of vehicles moving on the ground.
2
Content available Simulation tests of fleet vehicles periodic inspections timeliness: a case study
Matyja Tomasz, Stanik Zbigniew
Zeszyty Naukowe. Transport / Politechnika Śląska
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2022
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z. 115
75--91
EN
This study analyzed the case of a medium-sized workshop and the income from servicing individual customers. The management of the company observed some unused potential in the garage and plans to sign contracts with fleet customers for comprehensive maintenance of their vehicles. The key question was how many fleet vehicles could be additionally serviced without losing individual customers? In this work, a simulation model of a workshop was developed, treated as a system for queuing orders and vehicles. The model includes a subsystem of random generation of fleet vehicle mileage during the simulation. The idea of event-driven simulation and the Matlab/Simulink SimEvent environment library was used.
3
Content available Impact of the Static Pressure Measurement Accuracy on Barometric Altimeter Errors
Stanik Zbigniew, Matyja Tomasz, Kubik Andrzej
Safety & Defense
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2022
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2
62--71
EN
The horizontal movement of the pressure sensor in relation to air masses may cause erroneous indications of the altimeter due to the possible measurement of the total pressure, which is the sum of the static and dynamic pressure. This problem mainly concerns devices of small dimensions equipped with barometric altimeters made in MEMS technology, performing complex movements. Small dimensions make it difficult to arrange the pressure intake slots in a way that ensures the measurement of static pressure. Examples include drones (UAH) or bike computers. The aim of the research was to develop an altitude correction formula depending on the speed of the pressure sensor relative to air, which, contrary to those found in the literature, would take into account changes in air density with altitude. The theoretical analysis of the influence of the speed of movement on the indications of the barometric altimeter was evaluated in this paper based on the standard atmosphere model. Methods of correcting errors caused by the measurement of total pressure were proposed. The effectiveness of the proposed methods was verified with simulations (Matlab). Experimental studies were also carried out, which confirmed the theoretical considerations. The experiments performed showed that the problem of correcting errors caused by incorrect measurement of static pressure is very complex. The inertia of the barometer indications plays an important role. The direction of airflow and pressure distribution on the flowing object are also important. The results presented in this paper can be used in the design of systems that improve the quality of barometric altimeter readings. This is particularly important when designing low-budget drone navigation systems and it will improve flight safety.
4
Content available Safety of transport operations performed using pallet load units
Matyja Tomasz
Zeszyty Naukowe. Transport / Politechnika Śląska
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2021
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z. 112
145--156
EN
During transport operations, even under normal operating conditions, the loading unit is subject to inertial forces, which may cause deformation of the unit, and in extreme cases, its disintegration. Stretch film wrapping is the most commonly used method of securing a load unit. This paper presents a new simplified simulation model of a class A load unit, with a layered structure, secured with stretch film. Between the layers of packaging, stick-slip friction was applied. A method of estimating the containment force was also proposed. This model can be used to pre-determine the number of film layers necessary to ensure load stability. Simulations can reduce the amount of film used and the number of stability tests performed experimentally.
5
Content available Tilt test of a pallet load unit – simulation studies
Matyja Tomasz
Zeszyty Naukowe. Transport / Politechnika Śląska
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2020
|
z. 107
107--117
EN
This paper presents a dynamic model of a palletised load unit during a static tilt test. The stability (also called rigidity) of a load unit was evaluated. The palletised load unit was built of packages forming layers and protected against disintegration by stretch film. The aim of this study was to compare the results of a static tilt test with a commonly used and recommended dynamic acceleration test.
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