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Ing. Michal Frydrýn, Ph.D.

2025, PLoS ONE, 20, p. 1-28), ISSN 1932-6203

This study investigates the safety risks of Unmanned Aerial System (UAS) collisions with humans, focusing on impact dynamics through controlled crash testing. Utilizing a custom-designed drop mechanism, 49 impact tests were conducted on a Hybrid III anthropomorphic test device at various velocities and kinetic energies (7–24 m/s and 1–280 J). Tested UASs included a range of designs and weights (20 g to over 1 kg). Results demonstrated limitations in using kinetic energy models and peak head acceleration for injury prediction. The Head Injury Criterion showed greater consistency, reflecting the temporal profile of impacts. Findings revealed that UAS structural fragility reduces energy transfer at higher impacts through deformation and fracturing. This work underscores the need for improved testing protocols and nuanced safety standards.

2024, 2024 Smart City Symposium Prague - IEEE PROCEEDINGS, New York, IEEE Press), ISBN 979-8-3503-6096-7, ISSN 2831-5618

An integral part of modern cities within Smart City concepts is the development and related innovations in traffic control systems. New proposals need to be carried out in accordance with the applicable legislation and at the same time on a sufficient data base. This paper reflects the first conclusions of the research project SENDER, the aim of which is to develop, using deep learning methods, such a system that will warn drivers of impending danger in front of selected traffic intersections based on recognized data in the image from installed cameras. The paper mainly describes the process of selecting traffic situations in the area of intersections, which it is appropriate to warn the driver about. As part of the research, a state-of-the-art analysis was first carried out, which summarizes knowledge from current traffic control systems and the possibility of identifying collision situations, then the expert team defined collision situations that may occur in the node, including accompanying prioritization. On the basis of this identification, a specific intersection in the city of Brno was selected, which was fitted with cameras, and a test was conducted to determine whether the defined collision situations at the intersection actually occur. For the purposes of the developed system, this results in the specification of preferred collision situations, and these will then be simulated in variants with minor changes in the input parameters, in order to create a large enough database for learning the neural network.

2024, ISBN 978-80-214-6209-0

Odborná kniha se zabývá komplexním systémovým přístupem k analýze silničních nehod, obsahuje moderní metody dokumentace i analýzy silničních nehod vč. příkladů a zohledňuje změny v právním prostředí znalecké činnosti

2023, Aerospace Structural Impact Dynamics International Conference Proceedings 2023, Wichita, Kansas, Wichita State University, National Institute for Aviation Research)

This article summarizes a study that aimed to analyse and evaluate the ground-based risks associated with small Unmanned Aircraft Systems (sUAS) operations, particularly those that pose risks to the general public. Non-destructive tests were conducted to validate the currently used generalized kinetic energy (KE) relations based on objective data. The study found significant differences in observed speeds and KE between multi-rotor and fixed-wing aircraft, which were supplemented with other published data. While the currently used generalized relations between KE and mass of the sUAS are suitable for multi-rotor sUAS, fixed-wing aircraft may reach higher impact KE in case of failure. To assess repeatability and compatibility, a uniform crash test database was created from published crash tests performed with Anthropomorphic Test Devices (ATD), simplified ATD, and Post-Mortem Human Surrogates, supplemented with a series of dynamic crash tests with 18 multi-copter sUASs with mass ranging from 20g to 1.3 kg. Additionally, the study evaluated the effects of UAS design and frame material characteristics. Results show that UASs under the 250 g threshold do not pose a significant risk of injury in case of an impact, even in cases of high impact velocity (15 m/s). While inherent risks are related to increased impact kinetic energy, the design plays a factor in affecting the resulting injury severity. The study applied a new approach with rigid impactor tests to the database, which showed that the ATD was able to discern the severity of the impact and the increasing loads connected to the kinetic energy. For tests with a rigid object, a significant improvement in the correspondence between the KE Human vulnerability models and automotive prediction models was observed. The study also determined the relations between the biomechanical criteria (peak head acceleration, HIC15, Nij) and KE. As a result, the proposed approach can be used to estimate the maximum transmitted energy based on a comparison between UAS and rigid impactor tests.

2023, Proceedings of 31st Annual Congress of the European Association for Accident Research, Graz, European Association for Accident Research and Analysis), ISBN 978-80-7399-136-4

The modern era has brought a number of new options and sources for the analysis of traffic accidents. New devices for the processing of the EDR (Event Data Recorder) data, for example the Airbag Control Module (ACM) that stores certain vehicle parameter data at the time of a specific event (e.g. accident). This data is not stored elsewhere in the electronics and vehicle control systems. Although the vehicle’s main control unit stores FreezeFrame (recording of the vehicle’s status data in the event of a fault in some systems), the information about the vehicle’s status during the event is not so detailed. The article focuses on reading, interpretation and validation of EDR (Event Data Recorder) accident data using the CDR system. EDR or Event Data Recorder is a function of the airbag control unit, which records certain vehicle parameter data at the time of a specific event (e.g. accident). Four new crash tests provided by USI Zilina will be presented - Side impact during parallel driving of vehicles (Toyota Auris and Toyota Aygo), driving in an arc with braking and at the same time impact to the rear corner of the vehicle (Toyota Auris and Toyota Aygo), head-on collision with a stationary vehicle (Dodge Caliber and Toyota Aygo), Rear impact of the vehicle into a stationary vehicle (Volvo 60 and Toyota Auris). The purpose of the crash tests, whose results are the core of the paper, was to verify the reliability of the read data by comparing it with an independent measuring system. The tests were carried out as part of the research project VI20172020108 “Development of an Innovative Method for Identification of Road Traffic Offences Using Electronic Accident Data”. The project focuses on the development of an innovative method for identifying, proving and combating road traffic crime using modern technology and new knowledge in the field of measuring the dynamic characteristics. The tests, the obtained data and experience shows that the system based on retrieving post-crash data (specifically the CDR System) is a useful tool. The data from this system broadly corresponds to the data measured by an independent calibrated measurement system. The accident data storage function is based on the requirement of the National Highway Traffic Safety Administration (NHTSA). Federal Regulation (49CFR Part 563) subsequently standardised data stored by the EDR. In Europe, however, this system depends on the manufacturer’s decision ( to 2022) as to what format and what data the user will be able to retrieve. Similarly, it is up to the manufacturer what sensors (in terms of measured quantities and their measuring frequencies) will be installed in vehicles, which has a significant impact on the readings. New homologated cars from 2022 has to have EDR data base of EU rules.

2023, Young Transportation Engineers Conference 2022, Praha, České vysoké učení technické v Praze), p. 66-70), ISBN 978-80-01-07224-0, ISSN 2336-5382

The topic of the article are vehicle restraint systems. Specifically, the paper focuses on the safety analysis of the way of implementation of crash cushions. Within the safety analysis carried out on the territory of the Ústí Region of the Czech Republic, the most frequently occurring deficiencies in crash cushions and their possible impacts on road safety were identified. The output is the creation of catalogue sheets of crash cushions, which contain the most frequently installed crash cushions on the road network and a summary of methodological requirements for their adequate implementation. The work is intended to serve as an effective tool and a quality source of information for road managers and road safety auditors during their subsequent inspection.

2022, Heliyon, 8 (11), ISSN 2405-8440

The operational safety assessment of the unmanned vehicles is crucial for their subsequent practical use. The safety limit criteria used for the operation assessment, especially values closely related to the safety of persons and their vulnerability to collision with these vehicles, represent nowadays a significant limitation. This contribution presents the currently discussed and proposed human safety criteria for the UAS, evaluates the available data from the collision dynamic tests and computer modelling and provides the possibility to compare and evaluate these criteria on a validated set of data. A total of five small UAS, three multi-rotor quadcopters and two fixed-wing aircrafts were used to verify the current methods and serve as a basis for the assessment. The results of the measurements obtained through the crash tests demonstrate the excessive restrictiveness of the currently used kinetic energy threshold values and the limited value of some proposed criterions, e.g. the blunt criterion. On the contrary, they point to the appropriateness of the application of car vulnerability criterions. The UAS mass or kinetic energy tests represent an easily definable threshold value, however, the available data sets and the tests performed showed limitations of its applicability for the deformable and fragile UAS structures. The article aims to verify, based on its own impact tests, the adequacy of the evaluation of the safety criteria of the UAS operation in relation to the development of the current legislation that defines the conditions of use of these machines.

2022, Extraordinary Dynamic Experiments and Simulations, Les Ulis, EDP Sciences), p. 1-6), ISSN 2261-236X

This paper presents experimental testing of various types of concrete under impact loading by using a 2.8-second drop shaft. The drop shaft is located in the Josef Underground Laboratory and allows dropping a projectile from 40 meters that results in a maximal velocity of 100 km/h. Three basic types of concrete were used in the framework of this study. This was normal strength concrete, fibre-reinforced concrete, and high-performance fibre-reinforced concrete. The slabs were constructed 1700 mm × 500 mm × 70 mm in size and the clear span of the impacted slab was 1500 mm. Damage of the slab was recorded and the velocity of the projectile was measured with the high-speed camera before and after the impact. It was demonstrated that high-performance fibre-reinforced concrete has a higher ability to absorb and dissipate the kinetic energy of the impact that their lower strength counterparts.

2021, Soudní inženýrství, 32 (4), p. 36-45), ISSN 1211-443X

S novými metodami analýzy dopravních nehod a modernizací dokumentační techniky pro zajištění dostatečné a zároveň kvalitní formy podkladového materiálu přichází možnost užití elektronických nehodových dat (též data EDR). Nová legislativní úprava již dokonce vyžaduje od roku 2022 technologii záznamu nehodových dat jako povinnou výbavu u nových vozidel daných kategorií. U vozidel, která jsou již EDR vybavena, lze v současnosti vyčítat data, jež mohou výrazně usnadnit analýzu dané nehody. Tento článek předkládá ukázku dvou reálných dopravních nehod – v prvním případě se jedná o nehodu, při které by získaná data teoreticky mohla objasnit její průběh, a jednak nehody, při které byla data EDR k dispozici.

2021, Verkehrsunfall und Fahrzeugtechnik, 59, p. 144-155), ISSN 0724-2050

Ein weit verbreitetes Tool zum Auslesen der Unfalldaten ist das CDR-System von Bosch. Ziel der Crashtests, deren Ergebnisse den Kern dieses Aufsatzes bilden, war es, die Zuverlässigkeit der ausgelesenen Daten durch den Vergleich mit einem unabhängigen Messsystem zu verifizieren. Die Tests wurden im Rahmen des Forschungsprojekts VI20172020108 „Entwicklung einer innovativen Methode zur Identifikation von Verkehrsverstößen anhand elektronischer Unfalldaten“ durchgeführt.

2020, Thin-Walled Structures, 148, ISSN 0263-8231

Even though the number of deadly traffic incidents is decreasing, the proportion of motor vehicle crash deaths involving a collision with fixed objects is not. To address this issue, a novel load-bearing energy-absorbing system comprised of brittle blocks with thin-walled cellular structures is presented here, laying the foundation for the assessment of the system’s crashworthiness. Six brittle hexagonal cellular structures were subjected to quasistatic and impact tests. The crushing process, force-displacement curves, and a wide range of indicators of crashworthiness were examined. Samples with different levels of crashworthiness were identified and several observations that could guide future crashworthiness design are given. Our findings show that relatively small changes in the design can lead to production of blocks with distinguishable levels of crashworthiness.

2020, Materials Today: Proceedings, Amsterdam, Elsevier B.V.), p. 162-167), ISSN 2214-7853

Research presented in this paper is aimed to investigate the possibility of using a mobile concrete barrier based on a design of the Czech Hedgehog, which was a steel barrier developed before the Second World War to stop slow-moving armoured vehicles. The design is revisited using an ultra-high-performance fibre-reinforced concrete (UHPFRC) with additional steel reinforcement bars. Crash test experiments are conducted using an ordinary road vehicle moving at 48 km/h (30 mph). Final barrier design is capable of stopping the vehicle, although at least two rows of barriers were needed.

2020, ExFoS - Expert Forensic Science XXIX. mezinárodní vědecká konference soudního inženýrství, Brno, Vysoké učení technické v Brně - Ústav soudního inženýrství), p. 114-125), ISBN 978-80-214-5829-1

Příspěvek popisuje sérii crashtestů, při kterých bylo provedeno srovnání dat získaných ze systému EDR - Event Data Recorder a dat z nezávislého měřícího zařízení. Srovnání se zabývalo jak postřetovým zrychlením karoserie, tak i vyhodnocením předstřetového pohybu (např. zásah řidiče do řízení). Příspěvek prezentuje rozšířené možnosti analýzy nehod s pomocí získaných předstřetových dat o natočení volantu či rychlosti stáčení karoserie. Příspěvek dále popisuje aktuální novinky z pohledu legislativního zavedení systému EDR v Evropské unii.

2019, 2019 Konference - 25 let Fakulty dopravní, Praha, České vysoké učení technické v Praze), p. 122-126), ISBN 978-80-01-06545-7

Článek se zaměřuje na Ústavem soudního znalectví v dopravě řešený projekt VIMOT, jehož náplní je mj. návrh nové metody sloužící k odhalování, dokazování a potírání kriminality spojené s motorovými vozidly a její zavedení do praxe. V detailu je představena jedna ze stěžejních částí projektu, a sice nárazové testy orientované na ověřování funkčnosti a použitelnosti EDR (Event Data Recorder) dat a jejich čtení a interpretaci systémem CDR. CDR neboli Crash Data Retrieval je elektronický systém umožňující čtení dat zaznamenaných z různých senzorů a řídicích jednotek daného automobilu. Uživatelům tak může poskytnout přednehodové a ponehodové údaje, jejichž reálnost byla v rámci prezentovaných zkoušek ověřována porovnáním s referenčním systémem.

2019, 36th Danubia Adria Symposium on Advances in Experimental Mechanics, Pilsen, University of West Bohemia), p. 127-128), ISBN 978-80-261-0876-4

Mobile barriers can be used for more flexible protection against vehicle ramming attacks and can be easily removed when not needed. Since these barriers are usually not connected to the surface, their working principle usually uses just their mass and friction to stop the incoming vehicle. This means that they are very hard to set up, remove and transport. It is therefore desirable to have relatively light mobile barriers, that would interact with the impacting vehicle in such a way, that mass of the barrier is not the main stopping principle. One such barrier is the Czech Hedgehog developed in the 1930s for military defence. The barrier consisted of three steel beams of the same length connected in their centres. The intended stopping principle was that the Hedgehog would roll underneath a moving vehicle, lifting its tracks off the ground, therefore completely immobilising it.

2019, 28th Annual Congress of the European Association for Accident Research and Analysis (EVU), Graz, European Association for Accident Research and Analysis), p. 291-302), ISBN 978-80-554-1260-3

The article focuses on reading, interpretation and validation of EDR (Event Data Recorder) accident data using the CDR system. EDR or Event Data Recorder is a function of the airbag control unit, which records certain vehicle parameter data at the time of a specific event (e.g. accident). Various tools, such as the Bosch Crash Data Retrieval (CDR), can be used for subsequent data reading. The correctness and accuracy were assessed for obtained accidental data (pre- and post-crash). The presented results are one of the partial outputs of the VIMOT 4U project and were obtained as part of the crash tests carried out in autumn 2018.

2019, Pražská technika, 21 (6), p. 19-19), ISSN 1213-5348

Fakulta dopravní je od roku 2002 znaleckým ústavem pro znalecké obory Doprava a Spoje. Pro správu znalecké činnosti byl na fakultě založen specializovaný Ústav soudního znalectví v dopravě. Pracovníci tohoto ústavu se zabývají převážně analýzou silničních nehod a s tím spojenými znaleckými posudky, pomáhají ale také se zpracováním znaleckých posudků z dalších oblastí dopravy, na kterých primárně pracují další zaměstnanci fakulty z jiných ústavů/kateder.

2018, Verkehrsunfall und Fahrzeugtechnik, 56, p. 328-337), ISSN 0724-2050

Dieser Aufsatz befasst sich mit dem Lesen, Interpretieren und Validieren von EDRUnfalldaten (Event Data Recorder) mit dem CDR-System. Der Event Data Recorder ist eine Funktion des Airbag-Steuergeräts, der Fahrzeugparameter zum Zeitpunkt eines bestimmten Ereignisses (zum Beispiel Unfall) aufzeichnet. Für die anschließende Datenauslesung können verschiedene Werkzeuge, wie zum Beispiel das Bosch Crash Data Retrieval (CDRJ, eingesetzt werden. Die Genauigkeit wurde für die erhaltenen zufälligen Daten (Pre- und Post-Crash) bewertet. Die vorgestellten Ergebnisse sind Teilergebnisse des Projekts VIMOT 4U und wurden im Rahmen von Crashtests im Herbst 2017 ermittelt.

2018, EVU 2018 CONGRESS, Graz, European Association for Accident Research and Analysis), ISBN 978-80-554-1260-3

The article focuses on reading, interpretation and validation of EDR (Event Data Recorder) accident data using the CDR system. EDR or Event Data Recorder is a function of the airbag control unit, which records certain vehicle parameter data at the time of a specific event (e.g. accident). Various tools, such as the Bosch Crash Data Retrieval (CDR), can be used for subsequent data reading. The correctness and accuracy were assessed for obtained accidental data (pre- and post-crash). The presented results are one of the partial outputs of the VIMOT 4U project and were obtained as part of the crash tests carried out in autumn 2017.

2018, Thin-Walled Structures, 122, p. 597-605), ISSN 0263-8231

This paper lays the foundation for the development of a high-load bearing energy absorbing system with controlled deformation. Brittle ceramic blocks made of bricks with thin-walled cellular structures are presented and tested with impact loading. The authors demonstrate that such blocks are able to absorb impact energy because of the gradual brittle fracture process which occurs in the cellular structures. Full-scale specimens were subjected to laboratory impact tests: two non-deformable flat-nosed cart tests as well as two full-scale field crash tests involving passenger vehicles with crumple zones. The experiments were designed specifically to prove that block specimens are able to gradually absorb different levels of impact energy and to examine the applicability of using such blocks in the design of cross-drainage culverts. Based on a comparison of the two collisions with test culverts, the authors show that consequences of the collision can be significantly reduced by using brittle blocks with cellular structures in culverts. In fact, the crumple zone of the passenger vehicle which collided with a brittle block culvert was not crumpled; vehicle bounce off was eliminated and gradual deceleration of the vehicle was recorded.

2018, Soudní inženýrství, 29 (1), p. 35-42), ISSN 1211-443X

Článek představuje vybrané výsledky nárazových testů prováděných na podzim roku 2017 zaměřených na ověřování funkčnosti a použitelnosti systému CDR a jeho výstupů pro soudně-znaleckou praxi. CDR neboli Crash Data Retrieval je elektronický systém umožňující čtení dat zaznamenaných z různých senzorů a řídicích jednotek daného automobilu využitím systému EDR (Event Data Recorder). Uživatelům tak může poskytnout přednehodové a ponehodové údaje, jejichž reálnost byla v rámci prezentovaných zkoušek ověřována porovnáním s referenčním systémem. Součástí článku tak je porovnání výstupů CDR systému jako je zrychlení na karoserii s výsledky měření pomocí nezávislé měřicí soustavy.

2018, Sborník příspěvků konference Expert Forensic Science Brno 2018, Brno, Ústav soudního inženýrství), p. 169-179), ISBN 978-80-214-5600-6

Článek představuje vybrané výsledky nárazových testů prováděných na podzim roku 2017 zaměřených na ověřování funkčnosti a použitelnosti systému CDR a jeho výstupů pro soudně-znaleckou praxi. CDR neboli Crash Data Retrieval je elektronický systém umožňující čtení dat zaznamenaných z různých senzorů a řídicích jednotek daného automobilu využitím systému EDR (Event Data Recorder). Uživatelům tak může poskytnout přednehodové a ponehodové údaje, jejichž reálnost byla v rámci prezentovaných zkoušek ověřována porovnáním s referenčním systémem. Součástí článku tak je porovnání výstupů CDR systému jako je zrychlení na karoserii s výsledky měření pomocí nezávislé měřicí soustavy.

2017, Construction and Building Materials, 139, p. 64-80), ISSN 0950-0618

This paper is devoted to the experimental development of a high load bearing energy absorbing system (EAS) made of high performance concrete (HPC). The HPC investigated in this study was a selfconsolidating concrete with fast strength development which did not require heat curing or special mixing techniques. It was also an inherently very dense material which lead to the excellent environmental resistance and resulted in the long term durability. The proposed EAS was subjected to the thorough testing and its functionality was verified under impact and quasi-static loading. Numerical simulations were compared with the experimental data and good agreement was obtained. It was demonstrated that it is possible to develop an energy absorbing system made of high performance concrete with controlled impact force and deceleration. This demonstration together with load bearing capability and long term durability, predetermined the developed EAS for wide range of applications including those where currently manufactured energy absorbers cannot be applied.

2017, Soudní inženýrství, 28 (4), p. 188-194), ISSN 1211-443X

Poměr hodnot EES na vozidlech, jež se střetla, se obvykle dává do souvislosti s jejich hmotnostmi a vyjadřuje se vztahem pro přepočet hodnot EES mezi jednotlivými vozidly. Běžně používaný vztah ale neplatí obecně, je založen na předpokladech, které nebývají splněny při všech typech střetů – podmínky platnosti tohoto vztahu bývají splněny dokonce spíše výjimečně. Vědí to všichni znalci? Mnozí dosadí „své“ hodnoty do zmíněného vztahu, jako by byl exaktní obecně platný, a pokud poměr hodnot EES tomuto vztahu neodpovídá, považují to za hlavní kritérium pro výrok o tom, že se jedná o nehodu fingovanou – bohužel mnohdy mylně.