Get 20M+ Full-Text Papers For Less Than $1.50/day. Start a 14-Day Trial for You or Your Team.

Learn More →

Requirement Analysis for an Aerial Relay in Emergency Response Missions

Requirement Analysis for an Aerial Relay in Emergency Response Missions DE GRUYTER Current Directions in Biomedical Engineering 2020;6(3): 20203005 Jonas Gruner*, Albrecht Bloße, Max Rockstroh, Thomas Neumuth, and Philipp Rostalski Requirement Analysis for an Aerial Relay in Emergency Response Missions https://doi.org/10.1515/cdbme-2020-3005 Abstract: First aid of patients at the scene of an emergency requires an adequate flow of information. The publicly funded research project MOMENTUM aims at seamlessly connect- ing the point of care to the hospital. An unmanned aerial ve- hicle serving as a network relay may help in cases of limited or no mobile wireless connection, e.g. due to topographical circumstances. The aerial system may also provide situational awareness in cases of mass casualty incidents. For these two defined use-cases, safety and stability considerations are dis- cussed, and required flight times and payloads are defined. The relay can be connected to the ground via a cable or wireless Fig. 1: Concept of the MOMENTUM project. connection. It is concluded that the use-cases can be realized best when using a multicopter — either combined with a cable for independent flight times and reliable data communication pecially in medical haemorrhagic stroke cases. The required or a wireless solution to mitigate the risk from the increased wireless connection from the point of care to the hospital can payload while limiting flight time. For the first option, the pay- become unstable due to poor network coverage or blockage ef- load of the aircraft should be adjusted to ensure the power con- fects. An unmanned aerial vehicle (UAV) starting from the am- sumption in hover matches the power limitation of the cable. bulance may be used to relay the data stream by finding a suit- able place for improved signal reception to enable reliable data Keywords: Emergency Medicine, First Responder, Aerial transmission. The connectivity concept of the MOMENTUM Relay, Unmanned Aerial Vehicle (UAV), 5G, Drones project is summarized in Fig. 1. This paper discusses possi- ble use-cases and their consequent requirements for a UAV in 1 Introduction emergency rescue scenarios. The MOMENTUM project, funded by the German Fed- eral Ministry of Education and Research under grant 2 Use-Cases no. 16KIS1027, aims to connect emergency care from the place of an accident to the hospital without losing track of the 2.1 Connectivity patient’s situation and health data on the way to the medical trauma room and supporting telemedical assistance from the Signal improvements may help to implement telemedical as- experts in the hospitals. It is planned that the assistant will have sistance at the point of care as well as aid the transmission access to all crucial data from the ambulance, such as heart of high volume data such as ultrasound images and other rate, respiration, cognitive state and the ABCDE survey. The video streams. This, on the other hand, would make emergency gathered data may help to organize the right number of needed teams highly dependent on a reliable connection to a public surgeons for the medical trauma room and speed up the door cellular network. Special requirements, including low latency to CT/MRT time. Eventually, this could decrease mortality, es- and high data throughput, need to be achieved. The connec- tion can, however, be impaired by several means. First and *Corresponding author: Jonas Gruner, Universität zu Lübeck – foremost, an increased distance to the nearest cellular network Institute for Electrical Engineering in Medicine, Ratzeburger Alle tower also increases the path loss due to absorption effects [1]. 160, 23562 Lübeck, Germany, e-mail: j.gruner@uni-luebeck.de Furthermore, the signals are sensitive to strong absorption by Albrecht Bloße, Max Rockstroh, Thomas Neumuth, Universität solid structures such as buildings in urban environments or Leipzig - Innovation Center Computer Assisted Surgery, Leipzig, trees and hills in rural areas [2]. The blockage effect has al- Germany Philipp Rostalski, Universität zu Lübeck – Institute for Electrical ready been demonstrated in 2015 by Sundqvist [3]. Accord- Engineering in Medicine, Lübeck, Germany Open Access. © 2020 Jonas Gruner et al., published by De Gruyter. This work is licensed under the Creative Commons Attribution 4.0 License. 2 J. Gruner et al., Requirement Analysis for an Aerial Relay in Emergency Response Missions ing to the aerial measurements, there is an optimum height at be defined. As a possible UAV for both use-cases, fixed-wing which the signal strength becomes maximum. At this height, aircraft seem inappropriate. They require a runway which can- a direct line of sight to the transmitter cell was accomplished. not always be implemented in mobile use. Also, hovering at Therefore, this line of sight is beneficial for the stable data an optimal signal reception or filming position is ambiguous. connection required in rescue missions. A UAV can serve as The aircraft must move continuously to stay in the air. With a a mobile relay and establish a line of sight to the transmission balloon-based solution, both vertical take-off and hover flight tower. With appropriate sensor technology, one can determine are possible. In urban environments, however, the balloon lim- the optimal flight altitude and position of a relay unit. its the possibilities of movement. A so-called multicopter of- A UAV can also be useful as a flying base station [4]. As fers a compact, manoeuvrable solution to this problem. With such, it can be used to carry a so-called small-cell to support the appropriate programming, it can take off autonomously, the device-to-device connection of the medical equipment on- find an optimal position for the desired use-case and stay there scene with a dedicated secure cellular network. The position of in hover. The main limitation is the flight time, which is usu- the aerial cell can be optimized to ensure maximum coverage. ally less than half an hour for battery-powered systems. This [5, 6]. problem may be circumvented by a power supply via a cable, as described in section 3.2. Alternatively, hybrid solutions like the combination of an electric motor with a combustion engine 2.2 Situation Awareness or a combination of a fixed-wing aircraft with a multicopter are possible. For the further elaboration, multicopters are cho- The situation in cases of emergencies can be complicated sen as UAV platform due to their versatile scalability and the and overstraining. At the optimized aerial relay position, the resulting flexibility in choosing an air-to-ground-connection. UAV may be used to generate an overview of incidents from above. Inspired by the rescue copter system developed with the Deutsche Flugsicherung [7], the UAV is scanning the sur- 3.2 Air-to-Ground Connection rounding area. The camera operator can give feedback about the number and position of possible patients. The perspective The air-to-ground-connection (AGC) between the UAV and from above results in an advanced viewing angle, avoiding vi- the base station is an integral part for both the connectivity and sion blocking by cars, trees, and rocks. Consequently, it helps the situation awareness. The AGC needs to transmit the video to find patients in a shorter time and to figure out who is in data of a camera to the ground while connecting the on-board need [8]. The UAV can also be equipped with with a ther- relay to the ambulance. It can be accomplished via a wireless mal infrared camera, searching for patients even in night cases. connection or a cable solution. The advantage of a wireless Thermal cameras use a wavelength from 0.8 µm to 15 µm and connection is the omission of additional payload and the flex- can so see through smoke, rain, dust, fog and snow to get a ibility in positioning the UAV. On the other hand, a cable may clear image. Even under bright sunlight, the perception of pa- support a secure and uninterrupted data transfer connection, tients can follow the procedure of detecting a warm spot, mea- while wireless AGC is subject to signal interference. A ca- suring size, solidity and eccentricity. Moreover, confirmation ble can also supply the UAV with power. For this purpose, it is gathered through a coloured image [9–11]. must allow a high power throughput at minimum cable weight. The length of the cable should enable the aircraft to fly above the average building height, or in the forest above the aver- age tree height. The city of Berlin, for instance, reaches an 3 Requirements average building height of 13.4 m [12]. Trees in Central Eu- rope, however, grow to an average height of 30 m [13]. Since The described use-cases pose design challenges as well as the aircraft does not necessarily fly vertically upwards and the technical requirements to a UAV. Additional to the require- cable should not be on tension, a generously rounded length ments of the UAV, the ground station on the ambulance re- requirement of 80 m is assumed. quires a facility for take-off and landing and possibly a power The company Elistair (Champagne-Au-Mont-D’or, FR) connection for charging. offers a potential commercial solution for a cable system that meets the requirements in terms of weight and data transmis- sion [14]. The weight of the cable with about 2.5 kg at a length 3.1 UAV Design of 80 m includes an air module as a replacement for half of To discuss the necessary hardware for the use-cases in sec- the initial batteries. The system is limited by the maximum tion 2, the general aircraft architecture for the UAV needs to J. Gruner et al., Requirement Analysis for an Aerial Relay in Emergency Response Missions 3 allowed continuous power. This may hinder the use of more ings. For the elaboration of possible concepts, a hover time of powerful motors that allow an increased payload. more than 17 minutes is chosen as a minimum requirement. In case of a battery-powered UAV, the flight time is depen- dent on the available battery capacity and the current required 3.3 Technical Requirements of the UAV for the motors and the onboard components [15]. The motors’ current differs depending on their load. Thus, it is also varying In addition to safety and stability considerations, the require- in different heights and weather conditions. ments for the UAV are divided into two main parts, the neces- sary flight time and the payload. In the case of a multicopter, these parameters can be influenced by, among other things, 3.3.3 Payload the choice of the battery, the motors, and the propellers. In the following paragraphs, the considerations made for the param- The payload is the additional weight the aircraft can carry eters are based on the propulsion model for multicopters by while having sufficient thrust to hover. The weight of the air- Quan [15]. craft components, including the battery, are not considered as payload. The maximum theoretical payload depends on the to- tal thrust of the rotors and the weight of the frame and the 3.3.1 Safety & Stability propulsion system. The required payload highly depends on the use-case. The The main priority at the point of care is the safety of patients aerial relay for the aforementioned connectivity can, for in- and first responders. An aircraft on-scene must not on any stance, be implemented by two connected modems. One mo- account be a threat. The aircraft’s weight should, therefore, dem connects to the public cellular network, and another is be kept at its necessary minimum, to mitigate the associated part of a local network. An exemplary modem is the IoT Bit risk. Furthermore, the UAV must land safely, even if one of 4G by Altitude Tech (Bristol, GB), which is connected to a the engines is malfunctioning. In the case of a multicopter, Raspberry Pi. The weights are 95.3 g and 45 g, respectively this implies the use of at least six motors (hexacopter). An [18, 19]. The total payload of two modems can hence be es- equal redundancy needs to be planned for the mission-critical timated at 250 g. A possible small-cell on the aircraft would telemetry sensors. In addition to redundancies, failsafe actions constitute about 2 kg of additional payload. This weight is es- should be implemented. These may include a so-called return- timated based on a SCE4255 Small Cell by Sercomm (Shen- to-home functionality on radio-link or other sensor failures, zhen, CN) [20]. Furthermore, the camera and gimbal for sit- making the UVA land at its take-off location autonomously. uational awareness can be chosen to weigh below 600 g, us- A parachute may ensure a safe landing after mission-critical ing, for example, a Zenmuse XT2 assembly by DJI (Shen- incidents [16]. zhen, CN) [21]. A cable-based AGC, as discussed in sec- Another important safety aspect is flight stability. Espe- tion 3.2, is considered with 2.5 kg of additional payload. To- cially in urban areas, sudden wind gusts can occur. For a swift gether the mentioned components total to a required payload and wind stable flight, the aircraft should, therefore, not be op- of at least 5.35 kg when implementing the proposed use-cases. erated at its propulsion limit. For this reason, less than 80 % The weight of the frame and the propulsion system add another of the possible thrust created by the aircraft’s rotors should 2 kg to the required thrust of the motors. be required for maintaining hovering flight [15]. This leaves a margin for possible gusts or changes in air density. The thrust created by the rotors is dependent on the rotational speed of 4 Conclusion & Summary the motors, the propellers elevation angle, and the air density. The previous chapters have shown that a UAV can be bene- ficial in emergency missions by providing situational aware- 3.3.2 Flight Time ness and improved connectivity between the point of care and the clinic. The development of such a UAV shifts between the The UAV should be able to fly throughout the time the ambu- necessary requirements of safety and clear improvements at lance team is at the emergency scene, the so-called on-scene the point of care opposed to the additional effort using an air- time. In a large-scale study in Japan, 11585 cases were found craft. A UAV that suffices the requirements to implement all to have an interquartile interval of 13 to 23 minutes of on-scene the described use-cases is hard to implement since some re- time, with a median of 17 minutes [17]. Significant outliers quirements object with each other. The weight of an aircraft were also observed. Various other studies confirm these find- 4 J. Gruner et al., Requirement Analysis for an Aerial Relay in Emergency Response Missions that carries all payloads described in section 3.3.3 creates an lar networks. 2016 IEEE International Conference on Com- munications (ICC). IEEE; 2016:1–5. increased risk within an emergency mission. The high pay- [6] Kalantari E, Yanikomeroglu H, Yongacoglu A. On the Num- load would require large rotors and therefore corresponding ber and 3D Placement of Drone Base Stations in Wireless powerful motors. These motors, however, demand increased Cellular Networks. 2016 IEEE 84th Vehicular Technology power consumption, supplied by lager batteries or through the Conference (VTC-Fall). IEEE; 2016:1–6. cable. Larger batteries constitute another increase in the pay- [7] Virtual Disaster: Tilmans J, 2019. (Accessed: March 19, 2020, at https://www.fsd.rwth-aachen.de/go/id/donwu/lidx/1) load while a cable is limited by its maximum allowed power [8] Sibley AK, Jain T, Nicholson B, et al. MP01: Use of an un- throughput. manned aerial vehicle to provide situational awareness in a From the findings two possible implementations are con- simulated mass casualty incident. CJEM 2018;20(S1):S40. cluded to be feasible in the MOMENTUM project: One would [9] 10 Thermal Vision Cameras For Drones And How Thermal include a UAV optimized for connectivity enhancements by Imaging Works. Corrigan F, 2019. (Accessed: March 19, including a small-cell as well as modems for a relay on board. 2020, at https://www.dronezon.com/learn-about-drones- quadcopters/9-heat-vision-cameras-for-drones-and-how- A cable AGC enables nonstop flight during prolonged emer- thermal-imaging-works/) gency missions, while, however, limiting the positioning flex- [10] Drury JL, Riek L, Rackliffe N. A decomposition of UAV- ibility. Furthermore, the aggravated risk due to the increased related situation awareness. Proceedings of the 2006 ACM payload needs to be discussed further. Another option would Conference on Human-Robot Interaction;2006(May):88–94. be a relay UAV without small-cell and cable to mitigate the [11] Zaheer Aziz M, Mertsching B. Survivor search with au- tonomous UGVs using multimodal overt attention. 8th IEEE associated risk. In this case AGC is achieved by a point-to- International Workshop on Safety Security and Rescue point connection with a small-cell on the ground. This will, on Robotics. IEEE, 2010:1-6 the other hand, limit the flight time, but allows further position [12] Tröger E, Eberle D. Dichte Atmosphäre. Basel / Berlin / optimization, for situational awareness and enhanced connec- Boston: Birkhäuser; 2015. tivity. [13] Bäume. Tübingen-Bebenhausen: Forst Baden-Württenberg. As a future perspective, an integration of this relay func- (Accessed: March 19, 2020, at https://www.forstbw.de/wald- im-land/lebensraum/pflanzen/baeume) tionality into an existing hardware solution, for example, the [14] SAFE-T Product Presentation. Champagne-Au-Mont-D’or: Fotokite Sigma by Perspective Robotics (Zurich, CH) [22], Elistair; 2016. may also be possible. [15] Quan Q. Modeling and Evaluation of Propulsion System. In: Introduction to multicopter design and control. Singapore: Springer Singapore; 2017:78–95. [16] Al-Madani, B, Svirskis, M, Narvydas, G, Maskeliunas ¯ , R, Author Statement Damaševicius ˇ , R. Design of Fully Automatic Drone Parachute Research funding: The work was funded by the German System with Temperature Compensation Mechanism for Federal Ministry of Education and Research under grant Civilian and Military Applications. Journal of Advanced Trans- no. 16KIS1027. Conflict of interest: Authors state no conflict portation 2018:2964583. of interest. [17] Nagata I, Abe T, Nakata Y, Tamiya N. Factors related to prolonged on-scene time during ambulance trans- portation for critical emergency patients in a big city in Japan: a population-based observational study. BMJ Open References 2016;6(1):e009599. [18] IoTBit 4G Datasheet v1.6. Bristol: Altitude Tech; 2019. [19] Raspberry Pi FAQ. Raspberry Pi Founda- [1] Zhang L, Zhao H, Hou S, Zhao Z, Xu H, Wu X, et al. tion. 2016, (Accessed April 01, 2020, at A Survey on 5G Millimeter Wave Communications https://www.raspberrypi.org/documentation/faqs/) for UAV-Assisted Wireless Networks. IEEE Access [20] Sercomm SCE4255 - LTE Indoor Base Station Datasheet. 2019;7:117460–504. Shenzhen: Sercomm; 2016. [2] Al-Falahy N, Alani OY. Technologies for 5G Networks: Chal- [21] Zenmuse XT2 Quick Start Guide 1.2. Shenzhen: DJI; 2018. lenges and Opportunities. IT Professional 2017;19(1):12–20. [22] Aerial Situational Awareness for Every Firefighter. Zurich: [3] Sundqvist L. Cellular controlled drone experiment: Evaluation PERSPECTIVE ROBOTICS AG, 2019, (Accessed April 02, of network requirements. 2015. 2020, at https://cordis.europa.eu/project/id/856120) [4] Mozaffari M, Saad W, Bennis M, Debbah M. Drone Small Cells in the Clouds: Design, Deployment and Performance Analysis. 2015 IEEE Global Communications Conference (GLOBECOM). IEEE; 2014:1–6. [5] Bor-Yaliniz RI, El-Keyi A, Yanikomeroglu H. Efficient 3-D placement of an aerial base station in next generation cellu- http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Current Directions in Biomedical Engineering de Gruyter

Requirement Analysis for an Aerial Relay in Emergency Response Missions

Download PDF
4 pages

Loading next page...
 
/lp/de-gruyter/requirement-analysis-for-an-aerial-relay-in-emergency-response-FQxLaso2NY
Publisher
de Gruyter
Copyright
© 2020 by Walter de Gruyter Berlin/Boston
eISSN
2364-5504
DOI
10.1515/cdbme-2020-3005
Publisher site
See Article on Publisher Site

Abstract

DE GRUYTER Current Directions in Biomedical Engineering 2020;6(3): 20203005 Jonas Gruner*, Albrecht Bloße, Max Rockstroh, Thomas Neumuth, and Philipp Rostalski Requirement Analysis for an Aerial Relay in Emergency Response Missions https://doi.org/10.1515/cdbme-2020-3005 Abstract: First aid of patients at the scene of an emergency requires an adequate flow of information. The publicly funded research project MOMENTUM aims at seamlessly connect- ing the point of care to the hospital. An unmanned aerial ve- hicle serving as a network relay may help in cases of limited or no mobile wireless connection, e.g. due to topographical circumstances. The aerial system may also provide situational awareness in cases of mass casualty incidents. For these two defined use-cases, safety and stability considerations are dis- cussed, and required flight times and payloads are defined. The relay can be connected to the ground via a cable or wireless Fig. 1: Concept of the MOMENTUM project. connection. It is concluded that the use-cases can be realized best when using a multicopter — either combined with a cable for independent flight times and reliable data communication pecially in medical haemorrhagic stroke cases. The required or a wireless solution to mitigate the risk from the increased wireless connection from the point of care to the hospital can payload while limiting flight time. For the first option, the pay- become unstable due to poor network coverage or blockage ef- load of the aircraft should be adjusted to ensure the power con- fects. An unmanned aerial vehicle (UAV) starting from the am- sumption in hover matches the power limitation of the cable. bulance may be used to relay the data stream by finding a suit- able place for improved signal reception to enable reliable data Keywords: Emergency Medicine, First Responder, Aerial transmission. The connectivity concept of the MOMENTUM Relay, Unmanned Aerial Vehicle (UAV), 5G, Drones project is summarized in Fig. 1. This paper discusses possi- ble use-cases and their consequent requirements for a UAV in 1 Introduction emergency rescue scenarios. The MOMENTUM project, funded by the German Fed- eral Ministry of Education and Research under grant 2 Use-Cases no. 16KIS1027, aims to connect emergency care from the place of an accident to the hospital without losing track of the 2.1 Connectivity patient’s situation and health data on the way to the medical trauma room and supporting telemedical assistance from the Signal improvements may help to implement telemedical as- experts in the hospitals. It is planned that the assistant will have sistance at the point of care as well as aid the transmission access to all crucial data from the ambulance, such as heart of high volume data such as ultrasound images and other rate, respiration, cognitive state and the ABCDE survey. The video streams. This, on the other hand, would make emergency gathered data may help to organize the right number of needed teams highly dependent on a reliable connection to a public surgeons for the medical trauma room and speed up the door cellular network. Special requirements, including low latency to CT/MRT time. Eventually, this could decrease mortality, es- and high data throughput, need to be achieved. The connec- tion can, however, be impaired by several means. First and *Corresponding author: Jonas Gruner, Universität zu Lübeck – foremost, an increased distance to the nearest cellular network Institute for Electrical Engineering in Medicine, Ratzeburger Alle tower also increases the path loss due to absorption effects [1]. 160, 23562 Lübeck, Germany, e-mail: j.gruner@uni-luebeck.de Furthermore, the signals are sensitive to strong absorption by Albrecht Bloße, Max Rockstroh, Thomas Neumuth, Universität solid structures such as buildings in urban environments or Leipzig - Innovation Center Computer Assisted Surgery, Leipzig, trees and hills in rural areas [2]. The blockage effect has al- Germany Philipp Rostalski, Universität zu Lübeck – Institute for Electrical ready been demonstrated in 2015 by Sundqvist [3]. Accord- Engineering in Medicine, Lübeck, Germany Open Access. © 2020 Jonas Gruner et al., published by De Gruyter. This work is licensed under the Creative Commons Attribution 4.0 License. 2 J. Gruner et al., Requirement Analysis for an Aerial Relay in Emergency Response Missions ing to the aerial measurements, there is an optimum height at be defined. As a possible UAV for both use-cases, fixed-wing which the signal strength becomes maximum. At this height, aircraft seem inappropriate. They require a runway which can- a direct line of sight to the transmitter cell was accomplished. not always be implemented in mobile use. Also, hovering at Therefore, this line of sight is beneficial for the stable data an optimal signal reception or filming position is ambiguous. connection required in rescue missions. A UAV can serve as The aircraft must move continuously to stay in the air. With a a mobile relay and establish a line of sight to the transmission balloon-based solution, both vertical take-off and hover flight tower. With appropriate sensor technology, one can determine are possible. In urban environments, however, the balloon lim- the optimal flight altitude and position of a relay unit. its the possibilities of movement. A so-called multicopter of- A UAV can also be useful as a flying base station [4]. As fers a compact, manoeuvrable solution to this problem. With such, it can be used to carry a so-called small-cell to support the appropriate programming, it can take off autonomously, the device-to-device connection of the medical equipment on- find an optimal position for the desired use-case and stay there scene with a dedicated secure cellular network. The position of in hover. The main limitation is the flight time, which is usu- the aerial cell can be optimized to ensure maximum coverage. ally less than half an hour for battery-powered systems. This [5, 6]. problem may be circumvented by a power supply via a cable, as described in section 3.2. Alternatively, hybrid solutions like the combination of an electric motor with a combustion engine 2.2 Situation Awareness or a combination of a fixed-wing aircraft with a multicopter are possible. For the further elaboration, multicopters are cho- The situation in cases of emergencies can be complicated sen as UAV platform due to their versatile scalability and the and overstraining. At the optimized aerial relay position, the resulting flexibility in choosing an air-to-ground-connection. UAV may be used to generate an overview of incidents from above. Inspired by the rescue copter system developed with the Deutsche Flugsicherung [7], the UAV is scanning the sur- 3.2 Air-to-Ground Connection rounding area. The camera operator can give feedback about the number and position of possible patients. The perspective The air-to-ground-connection (AGC) between the UAV and from above results in an advanced viewing angle, avoiding vi- the base station is an integral part for both the connectivity and sion blocking by cars, trees, and rocks. Consequently, it helps the situation awareness. The AGC needs to transmit the video to find patients in a shorter time and to figure out who is in data of a camera to the ground while connecting the on-board need [8]. The UAV can also be equipped with with a ther- relay to the ambulance. It can be accomplished via a wireless mal infrared camera, searching for patients even in night cases. connection or a cable solution. The advantage of a wireless Thermal cameras use a wavelength from 0.8 µm to 15 µm and connection is the omission of additional payload and the flex- can so see through smoke, rain, dust, fog and snow to get a ibility in positioning the UAV. On the other hand, a cable may clear image. Even under bright sunlight, the perception of pa- support a secure and uninterrupted data transfer connection, tients can follow the procedure of detecting a warm spot, mea- while wireless AGC is subject to signal interference. A ca- suring size, solidity and eccentricity. Moreover, confirmation ble can also supply the UAV with power. For this purpose, it is gathered through a coloured image [9–11]. must allow a high power throughput at minimum cable weight. The length of the cable should enable the aircraft to fly above the average building height, or in the forest above the aver- age tree height. The city of Berlin, for instance, reaches an 3 Requirements average building height of 13.4 m [12]. Trees in Central Eu- rope, however, grow to an average height of 30 m [13]. Since The described use-cases pose design challenges as well as the aircraft does not necessarily fly vertically upwards and the technical requirements to a UAV. Additional to the require- cable should not be on tension, a generously rounded length ments of the UAV, the ground station on the ambulance re- requirement of 80 m is assumed. quires a facility for take-off and landing and possibly a power The company Elistair (Champagne-Au-Mont-D’or, FR) connection for charging. offers a potential commercial solution for a cable system that meets the requirements in terms of weight and data transmis- sion [14]. The weight of the cable with about 2.5 kg at a length 3.1 UAV Design of 80 m includes an air module as a replacement for half of To discuss the necessary hardware for the use-cases in sec- the initial batteries. The system is limited by the maximum tion 2, the general aircraft architecture for the UAV needs to J. Gruner et al., Requirement Analysis for an Aerial Relay in Emergency Response Missions 3 allowed continuous power. This may hinder the use of more ings. For the elaboration of possible concepts, a hover time of powerful motors that allow an increased payload. more than 17 minutes is chosen as a minimum requirement. In case of a battery-powered UAV, the flight time is depen- dent on the available battery capacity and the current required 3.3 Technical Requirements of the UAV for the motors and the onboard components [15]. The motors’ current differs depending on their load. Thus, it is also varying In addition to safety and stability considerations, the require- in different heights and weather conditions. ments for the UAV are divided into two main parts, the neces- sary flight time and the payload. In the case of a multicopter, these parameters can be influenced by, among other things, 3.3.3 Payload the choice of the battery, the motors, and the propellers. In the following paragraphs, the considerations made for the param- The payload is the additional weight the aircraft can carry eters are based on the propulsion model for multicopters by while having sufficient thrust to hover. The weight of the air- Quan [15]. craft components, including the battery, are not considered as payload. The maximum theoretical payload depends on the to- tal thrust of the rotors and the weight of the frame and the 3.3.1 Safety & Stability propulsion system. The required payload highly depends on the use-case. The The main priority at the point of care is the safety of patients aerial relay for the aforementioned connectivity can, for in- and first responders. An aircraft on-scene must not on any stance, be implemented by two connected modems. One mo- account be a threat. The aircraft’s weight should, therefore, dem connects to the public cellular network, and another is be kept at its necessary minimum, to mitigate the associated part of a local network. An exemplary modem is the IoT Bit risk. Furthermore, the UAV must land safely, even if one of 4G by Altitude Tech (Bristol, GB), which is connected to a the engines is malfunctioning. In the case of a multicopter, Raspberry Pi. The weights are 95.3 g and 45 g, respectively this implies the use of at least six motors (hexacopter). An [18, 19]. The total payload of two modems can hence be es- equal redundancy needs to be planned for the mission-critical timated at 250 g. A possible small-cell on the aircraft would telemetry sensors. In addition to redundancies, failsafe actions constitute about 2 kg of additional payload. This weight is es- should be implemented. These may include a so-called return- timated based on a SCE4255 Small Cell by Sercomm (Shen- to-home functionality on radio-link or other sensor failures, zhen, CN) [20]. Furthermore, the camera and gimbal for sit- making the UVA land at its take-off location autonomously. uational awareness can be chosen to weigh below 600 g, us- A parachute may ensure a safe landing after mission-critical ing, for example, a Zenmuse XT2 assembly by DJI (Shen- incidents [16]. zhen, CN) [21]. A cable-based AGC, as discussed in sec- Another important safety aspect is flight stability. Espe- tion 3.2, is considered with 2.5 kg of additional payload. To- cially in urban areas, sudden wind gusts can occur. For a swift gether the mentioned components total to a required payload and wind stable flight, the aircraft should, therefore, not be op- of at least 5.35 kg when implementing the proposed use-cases. erated at its propulsion limit. For this reason, less than 80 % The weight of the frame and the propulsion system add another of the possible thrust created by the aircraft’s rotors should 2 kg to the required thrust of the motors. be required for maintaining hovering flight [15]. This leaves a margin for possible gusts or changes in air density. The thrust created by the rotors is dependent on the rotational speed of 4 Conclusion & Summary the motors, the propellers elevation angle, and the air density. The previous chapters have shown that a UAV can be bene- ficial in emergency missions by providing situational aware- 3.3.2 Flight Time ness and improved connectivity between the point of care and the clinic. The development of such a UAV shifts between the The UAV should be able to fly throughout the time the ambu- necessary requirements of safety and clear improvements at lance team is at the emergency scene, the so-called on-scene the point of care opposed to the additional effort using an air- time. In a large-scale study in Japan, 11585 cases were found craft. A UAV that suffices the requirements to implement all to have an interquartile interval of 13 to 23 minutes of on-scene the described use-cases is hard to implement since some re- time, with a median of 17 minutes [17]. Significant outliers quirements object with each other. The weight of an aircraft were also observed. Various other studies confirm these find- 4 J. Gruner et al., Requirement Analysis for an Aerial Relay in Emergency Response Missions that carries all payloads described in section 3.3.3 creates an lar networks. 2016 IEEE International Conference on Com- munications (ICC). IEEE; 2016:1–5. increased risk within an emergency mission. The high pay- [6] Kalantari E, Yanikomeroglu H, Yongacoglu A. On the Num- load would require large rotors and therefore corresponding ber and 3D Placement of Drone Base Stations in Wireless powerful motors. These motors, however, demand increased Cellular Networks. 2016 IEEE 84th Vehicular Technology power consumption, supplied by lager batteries or through the Conference (VTC-Fall). IEEE; 2016:1–6. cable. Larger batteries constitute another increase in the pay- [7] Virtual Disaster: Tilmans J, 2019. (Accessed: March 19, 2020, at https://www.fsd.rwth-aachen.de/go/id/donwu/lidx/1) load while a cable is limited by its maximum allowed power [8] Sibley AK, Jain T, Nicholson B, et al. MP01: Use of an un- throughput. manned aerial vehicle to provide situational awareness in a From the findings two possible implementations are con- simulated mass casualty incident. CJEM 2018;20(S1):S40. cluded to be feasible in the MOMENTUM project: One would [9] 10 Thermal Vision Cameras For Drones And How Thermal include a UAV optimized for connectivity enhancements by Imaging Works. Corrigan F, 2019. (Accessed: March 19, including a small-cell as well as modems for a relay on board. 2020, at https://www.dronezon.com/learn-about-drones- quadcopters/9-heat-vision-cameras-for-drones-and-how- A cable AGC enables nonstop flight during prolonged emer- thermal-imaging-works/) gency missions, while, however, limiting the positioning flex- [10] Drury JL, Riek L, Rackliffe N. A decomposition of UAV- ibility. Furthermore, the aggravated risk due to the increased related situation awareness. Proceedings of the 2006 ACM payload needs to be discussed further. Another option would Conference on Human-Robot Interaction;2006(May):88–94. be a relay UAV without small-cell and cable to mitigate the [11] Zaheer Aziz M, Mertsching B. Survivor search with au- tonomous UGVs using multimodal overt attention. 8th IEEE associated risk. In this case AGC is achieved by a point-to- International Workshop on Safety Security and Rescue point connection with a small-cell on the ground. This will, on Robotics. IEEE, 2010:1-6 the other hand, limit the flight time, but allows further position [12] Tröger E, Eberle D. Dichte Atmosphäre. Basel / Berlin / optimization, for situational awareness and enhanced connec- Boston: Birkhäuser; 2015. tivity. [13] Bäume. Tübingen-Bebenhausen: Forst Baden-Württenberg. As a future perspective, an integration of this relay func- (Accessed: March 19, 2020, at https://www.forstbw.de/wald- im-land/lebensraum/pflanzen/baeume) tionality into an existing hardware solution, for example, the [14] SAFE-T Product Presentation. Champagne-Au-Mont-D’or: Fotokite Sigma by Perspective Robotics (Zurich, CH) [22], Elistair; 2016. may also be possible. [15] Quan Q. Modeling and Evaluation of Propulsion System. In: Introduction to multicopter design and control. Singapore: Springer Singapore; 2017:78–95. [16] Al-Madani, B, Svirskis, M, Narvydas, G, Maskeliunas ¯ , R, Author Statement Damaševicius ˇ , R. Design of Fully Automatic Drone Parachute Research funding: The work was funded by the German System with Temperature Compensation Mechanism for Federal Ministry of Education and Research under grant Civilian and Military Applications. Journal of Advanced Trans- no. 16KIS1027. Conflict of interest: Authors state no conflict portation 2018:2964583. of interest. [17] Nagata I, Abe T, Nakata Y, Tamiya N. Factors related to prolonged on-scene time during ambulance trans- portation for critical emergency patients in a big city in Japan: a population-based observational study. BMJ Open References 2016;6(1):e009599. [18] IoTBit 4G Datasheet v1.6. Bristol: Altitude Tech; 2019. [19] Raspberry Pi FAQ. Raspberry Pi Founda- [1] Zhang L, Zhao H, Hou S, Zhao Z, Xu H, Wu X, et al. tion. 2016, (Accessed April 01, 2020, at A Survey on 5G Millimeter Wave Communications https://www.raspberrypi.org/documentation/faqs/) for UAV-Assisted Wireless Networks. IEEE Access [20] Sercomm SCE4255 - LTE Indoor Base Station Datasheet. 2019;7:117460–504. Shenzhen: Sercomm; 2016. [2] Al-Falahy N, Alani OY. Technologies for 5G Networks: Chal- [21] Zenmuse XT2 Quick Start Guide 1.2. Shenzhen: DJI; 2018. lenges and Opportunities. IT Professional 2017;19(1):12–20. [22] Aerial Situational Awareness for Every Firefighter. Zurich: [3] Sundqvist L. Cellular controlled drone experiment: Evaluation PERSPECTIVE ROBOTICS AG, 2019, (Accessed April 02, of network requirements. 2015. 2020, at https://cordis.europa.eu/project/id/856120) [4] Mozaffari M, Saad W, Bennis M, Debbah M. Drone Small Cells in the Clouds: Design, Deployment and Performance Analysis. 2015 IEEE Global Communications Conference (GLOBECOM). IEEE; 2014:1–6. [5] Bor-Yaliniz RI, El-Keyi A, Yanikomeroglu H. Efficient 3-D placement of an aerial base station in next generation cellu-

Journal

Current Directions in Biomedical Engineering – de Gruyter

Published: Sep 1, 2020

Keywords: Emergency Medicine; First Responder; Aerial Relay; Unmanned Aerial Vehicle (UAV); 5G; Drones

There are no references for this article.