Salvatore Barba Sandro Parrinello Marco Limongiel lo Anna Dell ’Amico

editors

D-SITE Drones - Systems of Information on culTural hEr i tage.

For a spat ia l and social invest igat ion

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EditorsSalvatore Barba, Sandro Parrinello, Marco Limongiello, Anna Dell’Amico

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ISBN 978-88-6952-120-1 ISBN 978-88-6952-129-4 OA

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The present publication is part of the series “Prospettive multiple: studi di ingegneria, architettura e arte”, which has an international referee panel. “D-SITE, Drones - Systems of Information on culTural hEritage. For a spatial and social investigation” is a scientific text evaluated and approved by the Editorial Scientific Committee of Edizioni Pavia University Press of University of Pavia.

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D-SITE, Drones - Systems of Information on culTural hEritage. For a spatial and social investigation / Salvatore Barba, Sandro Parrinello, Marco Limongiello, Anna Dell’Amico (edited by) - Pavia: Pavia University Press, 2020. - 392 p.: ill.; 21 cm.

(Prospettive multiple: studi di ingegneria, architettura e arte)

ISBN 978-88-6952-120-1 ISBN 978-88-6952-129-4 OA

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MiChela Cigola1, daniele CaFolla2, arTuro gallozzi1, luCa J. SenaTore3, rodolFo Maria STrollo4

1 University of Cassino and Southern Lazio, Cassino, Italycigola@unicas.it, gallozzi@unicas.it

2 IRCCS NeuroMed, Isernia, Italycontact@danielecafolla.eu

3 Sapienza University of Rome, Rome, Italyluca.senatore@uniroma1.it

4 “Tor Vergata” University of Rome, Rome, Italystrollo@ing.uniroma2.it

aBSTraCTThe contribution briefly illustrates the HeritageBot project, currently in the prototype phase, which concerns the construction of a drone structure with robotic legs. The system is equipped with high dexterity locomotion mobility and the possibility of small flights. Its platform, structured in modular mode, allows to host various sensors, both commercial and specially developed, in order to intervene in the processes of knowledge and detection of Cultural Heritage, in critical situations and conditions and particularly difficult accessibility.

Keywords: HeritageBot, Cultural Heritage, survey, robotic arm, robotic tripod legs.

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1. InTroDUCTIon“Knowledge” is the key element for the protection and enhancement of Cultural Heritage. The objective of documenting, analysing, interpreting and contextualizing Cultural Heritage is the basis of this work. The intrinsic nature of monumental emergencies cannot be fully understood without integrating different disciplinary competences. These competences require the possibility to explore the object of investigation with multiple instruments. Any activities with the objective of studying archaeological, architectural elements, on an urban scale or in dangerous situations are based on the construction of an articulated system of knowledge. The latter, if properly structured, concerns several elements: historical, cultural, quantitative, qualitative, etc. While the qualitative elements are based on a rigorous scientific approach, the others are related to the sensitivity and interpretative capacity of the researcher/operator which often allow him to reach levels of knowledge that go well beyond the codified instrumental measurement operations. In the study of Cultural Heritage this process proves to be particularly evident as it is necessary to understand, structure and integrate information from various scientific fields. Increasingly often, we are called to operate in emergency and dangerous situations, for a first phase of knowledge of the damage, aimed at making the Good safe. It is therefore fundamental, in any case, that the database structure always responds to criteria of a scientific approach, commonly accepted by the community of scholars.

hybrID knoWlEDgE DEVICES for bUIlT CUlTUral hErITagE

The information for the knowledge of the Good must be well defined and correctly set up. In this context, the methodology and procedures for the survey constitute a guiding tool for a profound analysis of the artefacts, in accordance with the various specificities of the reality under investigation. Both in relation to the methodologies for data acquisition and the procedures for the selection, elaboration and restitution of the acquired information. This approach has fully characterized the phases of the survey, an activity in which there is a real duality between the phase of data acquisition and the modalities with which the study of the analysed object is carried out. In the usual survey processes, direct or instrumental, the acquisition phase is always subject to a careful preliminary study phase. This phase allows to guide and optimize the field operations, initially choosing the most significant aspects and discontinuities that will then be the object of measurement. Often, however, in sites of large dimensions or characterized by complex geometries or situations, traditional procedures have sometimes encountered difficulties in adequately completing the integral mapping of the asset under examination. On the other hand, recent technologies, such as 3D scanning or SFM (Structure for Motion)1, make it possible to acquire millions of points, necessary for a better description of the surfaces, without having to establish beforehand which ones to measure2. Within this framework, the use of mobile instrumentation guided at a distance is a considerable advantage, about some peculiar monumental emergencies and for all those situations in

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which accessibility to places is limited, dangerous and/or precluded. The possibility to operate remotely allows to work in safety and investigate spaces otherwise not visible. However, precisely because of the different characteristics of each architectural, archaeological or crisis context, it is not possible to identify an absolute rule to follow in order to carry out measurement operations. Therefore, so that the survey process - which is mainly instrumental and semi-automatic - can return the metric characters and the information necessary for the knowledge of the Good, it is necessary to operate according to a careful operative methodology, the only one that can guarantee the quality of the data to be used for the realization of reliable and scientifically valid elaborations. It is precisely in relation to this particular context that the idea of designing a hybrid drone was born, designed not only for data acquisition aimed at surveying, but also as an integrated tool - with specific mobile devices - for particular operations and movements, managed remotely.

2. roboT, DronE, hErITagEboTThe examples of robotic structures and drones that can be used until now in the field of Cultural Heritage knowledge, although tending towards miniaturization, are still characterized by considerable dimensions, or by movement structures based on tracks or wheels of various sizes and weights. Each system can operate at a distance within inaccessible areas, however, not all of them are able to meet some specific requirements in particularly complex investigation environments.Within this framework, this paper proposes a solution called HeritageBot, consisting of components that can be integrated and scalable according to the demands and needs of the survey context. The system, equipped with propeller module, mechanical legs and control unit for the management of communication and sensors, can operate a short flight and locomotion on legs. The set is specifically designed to meet certain demands for mobility and accessibility, paying attention to integrated handling.

The latter guarantees the use of the system both in dangerous conditions and in areas to which access is restricted for logistical reasons (Figure 1).The project currently in the prototype phase called HeritageBot is part of a FILAS Regione Lazio research project carried out by the Department of Economics of the University of Cassino and southern Lazio and involving researchers from the DART, LARM, IMPRENDILAB and FINLAB laboratories. The project also includes the participation of the Faculty of Architecture of Roma Sapienza and the Faculty of Engineering of the University of Rome Tor Vergata. In short, the current project involves the interaction of three cultural souls. In addition to the economic one, for the verification of the productive feasibility of the system, the mechatronic partners - for the structural apparatus from the platform - coordinated with the scholars of the archaeological and architectural survey are substantial and fundamental partners of the company. In particular, the latter have transferred their know-how to the project and highlighted the possible

Figure 1. The design of the HeritageBot Platform, Scheme for the conceptual design.

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The modules are designed as independent but integrated structures to easily adapt the platform to a wide range of applications. In particular, the equipment can be provided for different functions, using commercial solutions or specially developed. The demonstration prototype includes a sensor system for monitoring using LIDAR cameras and sensors. The HeritageBot platform is also designed to have a high autonomy in mobility and duration of operation (Figure 3).

4. ThE lEgSThe choice to create a locomotion module with legs to match to the propeller module is the great advantage of the platform. In fact the movement through robotic arts, allows to overcome a great limit still not solvable through the use of only propellers, that is to supply the possibility of a movement at low speed but able to be compatible with the problems of vision by the operator as well as for overcoming micro-obstacles difficult to solve by using the most invasive tracks or wheels. The movement on the legs allows to keep the structure under control and in balance thanks to the supports, guaranteeing a very low energy consumption

Figure 2. Experimentation field for the mobile platform handling tests.

peculiar problems that can be encountered in the operations of knowledge of the Cultural Heritage. This collaboration has also allowed a progressive evolution in the design of the platform, precisely in function of the first experiments carried out with the prototypes made, simulating - in the laboratory - critical situations of operation of the system (Figure 2).

3. ThE plaTforMThe project therefore foresees the development of a suitably sensed robotic platform, with mobility in locomotion and small flight with wireless management for monitoring and intervention operations on BBCC. The system has the purpose of data acquisition also with on-board storage capacity. The structure of the platform is modular both for mobility with innovative modules for high dexterity leg locomotion and to make a short flight with drone system, and for the instrumentation provided, aimed at monitoring and intervention in Cultural Heritage environments and products.

Figure 3. Left: render of the full conceptual design; right: wireframe of the prototyp’s shell, Patent Application no. 402017000025062-2017.03.07 (in Italy).

MICHELA CIGOLA, DANIELE CAFOLLA, ARTURO GALLOZZI, LUCA J. SENATORE, RODOLFO MARIA STROLLOHybrid knowledge devices for Built Cultural Heritage

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guarantee the necessary support to the leg module for the efficiency of the system also allowing, if necessary, a transport of a higher payload or a lower impact on the ground using the propellers to lighten the weight of the structure giving it a “floating” characteristic. In fact, the propeller module can be used not only for displacement but also to lighten the weight of the prototype to the supports operating at low speed, as well, can be used to straighten the prototype in case of accidental fall, or as a simple tool for overcoming all those obstacles otherwise impossible to overcome (Figure 5).

6. ThE roboTIC arMGiven its nature as a tool for knowledge, the prototype presents a further innovation, namely the presence of a robotic arm embedded in the body. The anthropomorphic arm can be guided remotely, constituting an additional aid instrument aimed at solving various problems related to the knowledge with different uses ranging from taking samples, to transporting and positioning sensors of different nature, to the physical movement of possible obstacles. The anthropomorphic arm a 4 Degrees of freedom structure with a two-finger gripper at the end. This mechanical structure has been chosen since it is very simple to reproduce and to control remotely by an operator but at the same time is very reliable (Figure 4b).

7. SEnSorSThe system allows multiple sensors to be used if necessary. Video and telemetry can be collected from the environment through onboard sensors, allowing bi-dimensional 360° and immersive photo-video mapping while additional sensors can be installed if required. The prototype is equipped with a main controller that is interfaced with all the other controllers of each sensor module and the transmitter for manual operation. It receives feedback from each module together with the

Figure 4. a: Tripod leg; b: embedded anthropomorphic arm.

which contributes to the possibility of the prototype remaining inside the building for several hours without the need to recharge or replace the batteries. All these features come from the mechanical structure of the Leg that is composed by three linear actuators converging in one point thanks to the mechanism described in the patent IT201600093695 (A1), this structure creates a tripod leg described in the patent IT201600097258 (A1). This tripod configuration has several advantages starting that can be added to the already mentioned ones. The step length is greater than the 100% the height of the leg improving the walking feature of the robotic platform. Another feature is the high payload capability with a small size. These two characteristics merged together gives another important one that is the small impact to the ground that is very important to avoid damaging a potentially important floor (Figure 4a).

5. ThE propEllEr MoDUlEThe propeller module is the element able to guarantee fast movements within the environment through the possibility to operate a short flight. The propellers, sized to guarantee the necessary payload for the installation of the sensors, allow a better accessibility to all the structures at height but at the same time

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Figure 5. A computational fluid dynamic analysis for the operation of the drone module in the designed platform.

input from the manual control by the user and manage the joint operations to achieve the desired task. In terms of hardware, to help the balancing HBIII an IMU sensor including a three-axis accelerometer, gyroscope and magnetometer has been used. In addition, the used IMU device has an embedded barometer. As the name implies, the accelerometer measures linear acceleration in up to three axes X, Y and Z. A very important parameter that allows a multicopter to stay stable is the detection of gravity done by the three-axis accelerometer. The 2D mapping is done using RPLIDAR 360, the mapping 3D is guaranteed by a Velodyne Portable Laser Scanner and the Video streaming is performed by a GoPro camera.

8. TEST CarrIED oUT for SUpporT DEVICE DESIgn on bUIlT CUlTUral hErITagETests were carried out in an archaeological environment that is difficult to access to support the design fases of our device. The tests analysed the ability of a Parrot mini-drone on wheels to move and be controlled remotely in various experiments. These tests were conducted in the Roman Theatre of Ancient city of Cassino, inside the Archaeological Area (Figure 6). The tests highlighted the difficulties in controlling the movement of the platform on wheels in a real environment: the presence of obstacles, even small

MICHELA CIGOLA, DANIELE CAFOLLA, ARTURO GALLOZZI, LUCA J. SENATORE, RODOLFO MARIA STROLLOHybrid knowledge devices for Built Cultural Heritage

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ones, and its poor ability to perceive their presence are important limits for all vehicles without leg-type structures. The second series of tests conducted for design definition of our prototype focused on the evaluation of the sensors. This was carried out in controlled environments aimed of defining the level of uncertainty and the ability to return data with a good degree of approximation. In order to evaluate the possibility of using a camera as a means of data acquisition for structure from motion procedures, operational tests were conducted to verify the significant frame survey processes and the operational difficulty of collecting data in inaccessible environments. This was carried out with the help of the Parrot mini-drone through the application of a commercial action camera. These tests supported the design of the remote-controlled robotic platform. It was possible to explain the different issues related to movement with legs and the choice of specific sensors for data acquisition for Built Cultural Heritage under specific operating conditions.

9. ConClUSIonSAll the part of the assembly is designed to be 3D Printed to achieve a low-cost and easy to reproduce structure. The experimentation carried out so far by the working group, has given satisfactory results and of sure interest for the research. The HeritageBot prototype, even though its nature is still being defined, has made clear how the development of a mobile medium, able to explore environments that are difficult to access in order to investigate the intrinsic nature of the artefact, is an important goal that, by exploiting innovative technologies, is able to increase the level of knowledge of what has been examined. In addition, the HeritageBot project foresees the definition of a methodological path specifically articulated in the procedures and methods of analysis and knowledge of Cultural Heritage. In second order it will be possible to obtain as a further objective the training of an intermediate professional class between detectors and robotics. This figure of operator, close to the skills related to the analysis and restoration of Cultural Heritage

Figure 6. Tests for support device design.

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will also have skills on the design and operation of integrated robotic systems. The value and the need for a connection between the various cultural souls are witnessed by the programs presented by the work team which, particularly with the HeritageBot project, has made it possible to fund various scholarships for young researchers with different cultural backgrounds. These young people, working together for the common goal of designing an integrated system for Cultural Heritage, have acquired multidisciplinary experiences, with a flexible professional training ready to the different demands of the working world. In this way, skills are formed between the worlds of restoration and robotics, able to contribute to the development and advancement in the analysis, conservation and restoration of Cultural Heritage, in line with the progress of technology.

noTE1 Photomodelling (Structure from Motion) develops from the theoretical assumptions of photogrammetry and allows the restitution of three-dimensional graphic models through the integration of the phases of survey, modeling and representation, extracting from the RGB coordinates, chromatic data, distances, vertices and profiles.

2 This statement is not intended to identify the methods for the massive acquisition of points as totally automatic processes, carried out without being filtered by the operator’s choices. In fact, laser scanning, in addition to the appropriate positioning of the instrument, presupposes a priori the choice of the scale of return of the processes, because this objective is linked to the specific definition of values linked to certain parameters (sample spacing and probe). In photomodelling, on the other hand, the number of shots, the quality and homogeneity of the photographic sockets in relation to accessibility and lighting conditions, the typology of the photographic socket scheme based on the morphology and geometry of the object under study, the level of detail of the model to be built are to be considered. See: De Luca L. 2011. La fotomodellazione architettonica. Rome: Dario Flaccovio Editore; Gaiani M. (ed.) 2015, I portici di Bologna. Architettura, modelli 3D e ricerche tecnologiche, Bologna: Bononia University Press.

bIblIographyBianchini C. (2014). Survey, modeling, interpretation as multidisciplinary components of a Knowledge System. SCIRES-IT, SCIentific RESearch and Information Technology, 4(1), 2014, pp. 15-24. doi: 10.2423/i22394303v4n1p15.

Cafolla D., Ceccarelli M., Wang M.F., Carbone G., (2016). 3D printing for feasibility check of mechanism design. International Journal of Mechanics and Control, 17(1), 2016, pp. 3-12.

Ceccarelli M., Cafolla D., Carbone G., Russo M., Cigola M., Senatore L.J., Gallozzi A., Maccio R.D., Ferrante F., Bolici F., Supino S., Colella N., Bianchi M., Intrisano C., Recinto G., Micheli A., Vistocco D., Nuccio M.R., Porcelli M. (2017). HeritageBot service robot assisting in cultural heritage. Proceedings - 2017 1st IEEE International Conference on Robotic Computing, IRC 2017, art. no. 7926580, 2017, pp. 440-445.

Ceccarelli M., Cafolla D., Russo M., Carbone G. (2018). HeritageBot platform for service in Cultural Heritage frames. International Journal of Advanced Robotic Systems, 15 (4), 2018. doi: 10.1177/1729881418790692.

Cerquetti M.G., Clini P., Bertuccioli L., Invernizzi L., Gasparini M. (2016). Integrated methodologies for the study, enhancement and sharing of archaeological heritage: the ArcheoFano project. SCIRES-IT, SCIentific RESearch and Information Technology, 6(2), 2016, pp. 81-92. doi: 10.2423/i22394303v6n2p81.

Cigola M., Gallozzi A., Senatore L.J., Di Maccio R. (2017). The Use of Remote Monitored Mobile Tools for the Survey of Architectural and Archaeological Heritage. Putting Tradition into Practice. Heritage, Place, Design. Cham, Switzerland: Springer International Publishing, 2017, pp. 756-765. doi: 10.1007/978-3-319-57937-5_78.

Federman A., Shrestha S., Quintero M.S., Mezzino D., Gregg J., Kretz S., Ouimet C. (2018). Unmanned Aerial Vehicles (UAV) Photogrammetry in the Conservation of Historic Places: Carleton Immersive Media Studio Case Studies. Drones, 2, 18.

Themistocleous K. (2018). Digitization issues in documenting cultural heritage with drones: case study of Foinikas, Cyprus. Earth Resources and Environmental Remote Sensing/GIS Applications IX. doi: 10.1117/12.2325459.

MICHELA CIGOLA, DANIELE CAFOLLA, ARTURO GALLOZZI, LUCA J. SENATORE, RODOLFO MARIA STROLLOHybrid knowledge devices for Built Cultural Heritage

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