Sensors used in UAVs

Sensors used in UAVs are mostly categorized into Navigation Sensors and Sensors used for missions. Most of the sensors used for navigations on UAVs comprise of sensors such as Global Navigation Satellite Systems (GNSS) which includes the Global Positioning Systems and the Inertial Navigation System. GPS and INS complement each to the point that they are the preferred sensors for the majority of autopilot systems (Mejias, Lai, & Bruggemann 2015)

Other sensors used for navigations or surveillance include the Electro-Optical (EO) Sensors and Radio- Wave Sensors

Electro Optical (EO) Sensors;

i.                    Visible Spectrum: These are either digital still cameras or machine vision webcams that are used to take pictures or provide a continuous stream of images respectively. This type of sensor cameras is mostly used in aerial photography.

ii.                  Infrared sensors:  Infrared cameras that are sensitive to light at a long wavelength and form images using infrared radiation in the spectrum at wavelengths of 14,000nm.

iii.                Hyperspectral Imaging:  these are sensors that acquire image data simultaneously in multiple adjacent spectral bands. This type of sensor is mostly used for identifying different compositions of materials

Radio- Wave Sensors

Airborne Radio Detection and Ranging (Radar) and Light Detection and Ranging (Lidar) systems are used to determine the range, altitude, direction and speed of objects by measuring signal return time of transmitted controlled radio pulses. Radar sensors such as the Ground Proximity Warning Systems (GPWS) have been widely used in the aviation world. Radars are also recently being used in the automotive industry for collision warning systems. ( Mejias, Lai, & Bruggemann 2015)

Exteroceptors (External) and Proprioceptors(Internal)

Exteroceptors are sensors that allow the robot of unmanned systems to perceive or interact with its environment whole Proprioceptors sensors measure the internal kinematic and dynamic parameters of the unmanned system. Such parameters include the amount of torque exerted by the actuator. Exteroceptors are grouped into contact and non-contact sensors. The contact sensors perceive their environment by touching the objects and shaped in its environment while non-contact sensors obtain information about its environments without physical contact. Such non-contact sensors include pneumatic sensors, ultrasonic sensors, and optical sensors (Gupta, Arora, & Wescott, 2016)

Sensor Review
 https://ieeexplore-ieee-org.ezproxy.libproxy.db.erau.edu/xpls/icp.jsp?arnumber=4772754

For the sensor review, I have selected the journal article that uses the Miniature Strapdown Inertial Navigation System (mini INS) with inertial microelectromechanical systems (MEMS) for control of different UAVs in the autopilot mode. Inertial Navigation System sensors as noted earlier are used for navigation. The Miniature Strapdown Inertial Navigation System (mini INS suit this mission as it is low cost with small overall dimensions and consumes very low power. The sensor can provide the required accuracy of determining the attitude, position, and velocity of the UAV. The use of the inertial system as the main component of the autopilot provides the required flying accuracy with the capability of UAV destination to the desired waypoint at a given time and tracking the predefined path. (Kortunov, Dybska, Proskura, & Kravchuk, 2009)

The disadvantage of using this system in an autonomous mode is hampered since the instability of MEMS sensor characteristics causes fast accumulation of errors in the determination of navigation data. The effective approach to solving this problem is the integration of mini INS with different external measuring devices like GPS navigation, which is considered as the most precise facilities of determination of moving object position, magnetic compass, and air data sensor (Kortunov, Dybska, Proskura, & Kravchuk, 2009)

References

Gupta, A. K., Arora, S. K., & Wescott, J. R. (2016). Industrial automation and robotics: An introduction., 390-401. Retrieved from https://ebookcentral-proquest-com.ezproxy.libproxy.db.erau.edu/lib/erau/reader.action?docID=4895078&query=industrial+automation+and+robotics%C2%A0(Links%20to%20an%20external%20site.)#

Kortunov, V. I., Dybska, I. Y., Proskura, G. A., & Kravchuk, A. S. (2009). Integrated mini INS based on MEMS sensors for UAV control. Retrieved from https://ieeexplore-ieee-org.ezproxy.libproxy.db.erau.edu/xpls/icp.jsp?arnumber=4772754

Mejias, L., Lai, J., & Bruggemann, T. (2015). Sensors for missions Springer, Dordrecht. Retrieved from https://search.credoreference.com/content/entry/sprunmanned/sensors_for_missions/0

Reusable Rocket Launchers

The U.S. military began experimenting with unmanned aircraft as early as World War I. By World War II, the unmanned craft could be controlled by radio signals, usually from another aircraft. Vehicles that could return from a mission and be recovered appeared in the late 1950s. Today, Unmanned Aerial Vehicles (UAVs) perform a wide range of missions and are used by all four branches of the military.  UAVs are used to satisfy requirements for military and commercial markets to include reconnaissance, surveying, wildlife management, Space missions, border control, commercial delivery, and many more missions.

Progress in recent technologies has enabled space drones to be considered as valuable platforms for planetary exploration. Thus, drones and especially Unmanned Aerial Vehicles (UAVs) have had extremely high progress to be applied for planetary science missions.  (Hassanalian, Rice, & Abdelkefi, 2018). There is also the chance of using UAVs and rockets for tourism to Mars. However, whether the mission is for tourism or research, space exploration is very expensive. One of the most expensive parts of launching a UAV into space is the launch vehicle. Most of the launch cost comes from building the rocket, which flies only once. Compare that to a commercial airliner – each new plane costs about the same as Falcon 9, but can fly multiple times per day, and conduct tens of thousands of flights over its lifetime. Following the commercial model, a rapidly reusable space launch vehicle could reduce the cost of traveling to space by a hundredfold. (Post, 2015).

SpaceX has the designed the Falcon 9 rocket and the reusable launcher called the Grasshopper, a 10-story Vertical Takeoff Vertical Landing (VTVL) booster/launcher. While most rockets are designed to burn up on reentry, SpaceX rockets are designed not only to withstand reentry but also to return to the launch pad for a vertical landing.   The Grasshopper VTVL vehicle represents a critical step towards this goal. To date, a fully reusable vehicle has not been successfully developed.  As such, the Grasshopper testing program is incredibly challenging.  Below are videos of our most recent test in which Grasshopper rose 24 stores--or over 260 feet--hovered for approximately 34 seconds and landed safely back on the centermost part of the pad.  Spacex ’s rapidly reusable space launch vehicle could reduce the cost of reaching Earth orbit by a hundredfold(Shanklin, 2013).


SpaceX demonstrated the effectiveness of the reusable launcher by successfully launching an Unmanned Falcon 9 rocket into space. the Falcon 9’s Crewed Dragon capsule separated from the first stage booster which came back to Earth, using its engines to slow for a touchdown on SpaceX’s drone ship in the Atlantic Ocean, ready for inspections and refurbishment before another mission This success has opened a new front in space exploration. The launch of the unmanned crewed rocket opens an opportunity for spaceX and Elon Musk to achieve the aim of sending humans to space on space tourism and setting up a space station on Mars. The US military is looking to incorporate this system of launch into its fleet of space UAVs after full testing.

References

Hassanalian, M., Rice, D., & Abdelkefi, A. (2018). Evolution of space drones for planetary exploration: A review. Progress in Aerospace Sciences, 97, 61-105. doi:10.1016/j.paerosci.2018.01.003

Post, H. (2015). Reusability: The key to making human life multi-planetary. Retrieved from https://www.spacex.com/news/2013/03/31/reusability-key-making-human-life-multi-planetary

Shanklin, E. (2013). Reusability. Retrieved from https://www.spacex.com/reusability-key-making-human-life-multi-planetary

UAS Security Challenges

As early as 2004, NASA’s “Civil UAV Capability Assessment” listed 30 categories of private-sector organizations with a potential interest in UAV use, including those in forestry management, crop dusting, and coastal search and rescue. (Pitchford, n.d.). The number of UAS has since increased to tens of thousands since then. With this expansion comes the security challenges. The FAA has had challenges in regulating UAS use and they continue to update regulations to enable safe and efficient use of UAS.

Notably, even if FAA standards are imposed, safety might still be at risk unless security standards are mandated. The 2011 crash of a CIA drone in Iran underlines that unless a system can withstand hacking, safety remains at risk. In that incident, local authorities claimed that they had diverted the vehicle by hacking its GPS. Their claim gained credence when Professor Todd Humphreys of the University of Texas and a group of U.S. researchers hacked a UAV in front of representatives of the U.S. Department of Homeland Security. The team spoofed an onboard GPS receiver by mimicking the actual signals sent to the global positioning device to trick the UAV into following different commands.

In more recent times, people have used UAS to cause disruptions to flights and passenger travels. Tens of thousands of passengers have been disrupted by drones flying over one of the UK's busiest airports. The number of aircraft incidents involving drones has grown dramatically in the past few years. In 2013 there were zero incidents, compared to almost 100 last year(BBC, 2018).

With these security threats and disruptions, it is very important to quickly obtain UAS information such as registration number during or after incidents. Previously, owners of small unmanned aircraft were permitted to enclose its FAA-issued registration number in a compartment inside of the device, as long as the compartment could be opened without a special tool. (Ashworth, 2019). However, members of the law enforcement and security communities subsequently expressed concerns that the current rule presents an imminent risk of harm to first responders. Law enforcement and security officials advised that requiring first responders to physically handle or disassemble a drone to obtain the registration number poses an unnecessary safety and security risk to those individuals, as well as to others in the area, because of the potential for the UAS to conceal an explosive device in an enclosed compartment. (Coburn, 2019).

To mitigate the imminent security concerns to law enforcement, the FAA issued new regulations requiring unmanned aircraft systems (UAS or drones) to display their registration number on the exterior of the aircraft, effective February 25, 2019. (Coburn, 2019).

This new rule reflects the challenges and complexity of the UAS industry. Comprehensive rules and standards will continue to change as UAS reaches a wider use and more challenges emerge.

References

Ashworth, S. (2019). Show me the sticker: FAA issues new rules on drone registration labels. Retrieved from https://www.radioworld.com/news-and-business/business-and-law/show-me-the-sticker-faa-issues-new-rules-on-drone-registration-labels

BBC. (2018, December 20,). Drones ground flights at Gatwick. Retrieved from https://www.bbc.com/news/uk-england-sussex-46623754

Coburn, T. (2019). FAA announces new drone rule requiring visible UAS registration number. Retrieved from https://www.jdsupra.com/legalnews/faa-announces-new-drone-rule-requiring-89675/

Pitchford, M.(n.d.) What's needed to ensure safety and security in UAV software. Retrieved from http://mil-embedded.com/articles/whats-needed-ensure-safety-security-uav-software/

Case Analysis Effectiveness

The case analysis tool for this course was a very effective learning tool for keeping communication with peers.  This method and format of research and analysis are very structured. The case analysis tool allows the student to research the subject matter and gather as much information as possible that pertains to the overall effectiveness of the topic.

          The case analysis tool helps the student focus on the main topic or points of the project while analyzing how it will impact a society or industry. The case analysis tool takes a student’s view and idea on a subject and further expands the scope across a wider view to further test the relevance or irrelevance of an idea on the problem.

The case analysis project can help students think critically about the role of UAS in the future of UAS civilization. It made me think about the issues that will limit the applications that the system would be used for. To utilize UAS to its full potential, all issues are needed to be addressed.

The case analysis tool can be used in many business settings which offer an employee the opportunity to present a case before a team and provide their point of view on various subject matter ranging from which investments to make, capital investments, program decisions, design choices, and engineering changes.

          Finally, the case analysis tool enables peer review work done, this is very helpful as it ensures that ideas are being exchanged between student peers and in a real project setting, communication about a project is in a good flow. The layout of the tool also aids the student by offering the possibility of expanding the development of their research design. The recommendations provided by both the tutor and peers helps the student gain a much deeper appreciation and understand of the research and analysis process, which is the main key or benefit from utilizing the case analysis tool in a student’s research project. The initial peer review of the abstract and then the second peer review of the rough draft are very helpful but a peer review of the final product would provide that last check that you are on track before submission.  I also think the course work should provide an example of what a good peer review looks like.  There were large variations in from student to student on the peer reviews.

Request For Proposal

The occurrence of a disaster threatens the lives of people and animals as well as causes the destruction of property. During the management and prevention of a disaster, it is important that the decision makers have access to extensive information regarding the situation so as to respond effectively (Apvrille, Roudier, & Tanzi, 2015). Information regarding the state of the disaster should be delivered as swiftly and as accurately as possible to ensure that a proper analysis of the situation is made. Constantly updated visual images are crucial during the planning of the response as it informs the search and rescue team on the progress of the disaster. For these requirements, unmanned aerial systems promise to deliver more effectively as compared to manned aircraft or other photogrammetric options such as satellites. The setbacks of these other options were experienced during the occurrence of Hurricane Katrina in 2005 whereby thousands of people lost their lives due to delays in the assessment of the situation as it unfolded (Francis, 2012). Application of unmanned aerial systems in the prevention and management of disaster could potentially lead to the saving of many lives in the future.

Baseline Requirements

Transportability

The entire system (all elements) shall be transportable (in a hardened case) and weight less than 50 lbs (one-person lift).

•    Transportation case shall provide a cutout for air vehicle element.

•    Transportation case shall provide cutout enabling ground control equipment.

•    Transportation case shall provide a cutout for power equipment.

•    Transportation case shall be able to withstand a drop from a height of five feet with minimal damage to the surface.

•    Transportation case shall have a weight that is less than 50 pounds when filled with UAS components.

Cost

The cost of equipment shall be less than $100,000 (equipment cost only)

Air vehicle element

•    Shall be capable of flying up to 500 feet altitude above the ground level (AGL)

•    Shall be capable of sustaining flight for more than one hour (at loiter speed)

•    Shall be capable of flying over an operational radius that is at least one mile

•    Shall be deployable and in position over the area of the mission in less than 15 minutes

•    Shall be capable of manual operation as well as autonomous operation

•    Shall be capable of capturing telemetry such as the altitude, magnetic heading, position of latitude and longitude, and the orientation

•    Shall provide power to the payload, telemetry sensors, and the data-link

•    Shall be capable of orbiting (i.e., fly in circular pattern around) or hover over an area or object of interest

Command & Control (C2)

•    Shall be capable of both manual and autonomous operation

•    Shall provide flight control that is redundant so as to prevent flyaway

•    Shall be capable of depicting the telemetry of air vehicle element

•    Shall visually depict the views of payload sensors

Payload

•    Shall be capable of recording color video during the day at the height of 500 feet AGL

•    Shall be capable of operating infrared (IR) video up to 500 feet AGL

•    Shall be interoperable with command and control as well as the data-link

•    Shall employ power made available by the air vehicle element

Data-link (communications)

•    Shall be capable of a communication range that exceeds a visual line of site of two miles

•    Shall provide a redundant communication capability as backup for the command and control

•    Shall employ power made available by the air vehicle element

Support equipment

The design shall identify any support equipment that is required to support and enhance operation

The Mission

A high altitude long endurance (HALE) UAV was chosen for the development of an unmanned aerial system that is cost and time efficient during search and rescue missions. This UAV was developed by using a selection of commercial off the shelf equipment. This UAV will be of great importance during disaster management and search and rescue missions by fire and police departments. Deploying a UAV to take detailed photographs and photogrammetric data obtained from various sensors and cameras can tremendously accelerate rescue efforts (Barnhart, 2012). It is also important that the UAV can be transported easily while also being capable of having a payload comprising a command and control system that is reliable. The development of the UAV will be done in 3 years.

Derived Requirements

Command and control station

•    Shall have waterproofing and dust proofing

•    Shall have redundant flight control during flight

•    Shall have encrypted hardware and firmware

•    Shall have a global positioning system (GPS) for location during manual or autonomous flights

•    Shall have a network system to distribute collected information to the web

•    Shall incorporate geo-correction and redistribution of information.

•    Shall have upload plans using multiple communication paths

Payload

•    Shall be capable of carrying a payload of 10 pounds

•    Shall have infrared and thermal cameras for capturing photographs and video

•    Shall have an audio transmission system

•    Shall have a payload capable of carrying the power source 

Air vehicle element

•    Shall be capable of flying up to 5000 feet from the ground level

•    Shall be capable of maintaining flight for more than two hours

•    Shall be capable of manual and autonomous operation

•    Shall have power capable of operating payload, sensors and communication systems

Development Process

The development process of choice will be the 10-phase waterfall method.

1.    Concept design                1 month

2.    Concept research              2 months

3.    Preliminary design           2 months

4.    Detail design                    6 months

5.    Specimen test                   3 months

6.    Prototype build and test   7 months

7.    Development                    5 months

8.    Certification                     1 month

9.    Production                       4 months

10.    Support                          5 months

Additional time will be spent on the detailed design phase to ensure that the command and control station is in proper working condition. The most crucial phase is the prototype and build test as all components of the UAV are effectively operational.

Conclusion

Due to the expected challenges during the management of a disaster, these requirements were chosen for the design of the UAV; command and control, payload and air vehicle element. The command and control station was considered due to its crucial role in providing an interface for interaction with the UAV as well as transmitting information. Waterproofing was necessary to ensure that components maintained operation even in extreme weather conditions (Li, Fabbri, & Zlatanova, 2007). The payload was also important as it needed to consider the sensors, cameras and communication systems that would be carried onboard. Designing the payload to accommodate more weight enhances the flexibility and capabilities of the UAV, hence enabling it to carry out different missions. Designing the vehicle element dictates factors such as the maximum altitude and the endurance of the UAV. An effective disaster management UAV should be capable of flying at high altitudes so as to capture sufficient photogrammetric data useful in the analysis of the disaster (Sarker, Hannan, Shahed, Rahman, & Sakib, 2016). The UAV should also be capable of flying for extended periods to enable it to gather as much information as possible during its flight. The use of UAVs in the management of disasters can significantly improve the success rate of rescue missions, thereby saving the lives of more people.

References

Apvrille, L., Roudier, Y., & Tanzi, T. (2015). Autonomous drones for disasters management: Safety and security verifications. Retrieved from  http://dx.doi.org/10.1109/ursi-at-rasc.2015.7303086

Barnhart, R. (2012). Introduction to unmanned aircraft systems. Boca Raton: CRC Press.

Francis, M. (2012). Unmanned Air Systems: Challenge and Opportunity. Retrieved from http://dx.doi.org/10.2514/1.c031425

Li, J., Fabbri, A., & Zlatanova, S. (2007). Geomatics solutions for disaster management (1st ed.). New York: Springer.

Sarker, T., Hannan, P., Shahed, S., Rahman, N., & Sakib, S. (2016). Conceptual design of a low cost flight data acquisition system for analyzing flight behavior of small unmanned aerial vehicles. Retrieved from http://dx.doi.org/10.1109/iccitechn.2016.7860261

UAS Mission

Unmanned Aerial Systems refer to aircraft that fly autonomously without the need of a human pilot operating it onboard. An operator situated on the ground controls an unmanned aircraft system. An unmanned aerial system employs the use of aerodynamic forces in the provision of vehicle lift (Fahlstrom & Gleason, 2013). The design of an unmanned aerial system mission is significantly different from that of a manned aircraft. During the design and implementation of an unmanned aerial system mission, it is vital that several factors are put into consideration. To attain success during the implementation of a mission, a tremendous amount of planning is necessary before the execution of the mission. Critical categories during the design and implementation of an unmanned aerial system mission include studying the maps of the area, the definition of the specifications of the products, planning of the aerial imagery, selection of the procedures and personnel, estimation of costs and development of a delivery schedule (Grace, 2013).

Unmanned aerial systems have undergone major developments over the years, thereby expanding their use to applications other than the military. For instance, unmanned aerial systems can be used in the prevention and management of disasters. UAS can be applied in the management of natural disasters such as forest fires, earthquakes, and floods (Austin, 2013). They are essential in observing and analyzing disasters, as well as conduction of search and rescue missions. An unmanned aircraft can be used in the searching for survivors of an earthquake. In addition to search and rescue missions, UAS can be used in the gathering of information during other types of disasters such as oil spills in the ocean. UAS platforms are based on four main characteristics which include the following; range, flight altitude, endurance and the maximum weight capable of the aircraft during take-off. A broad classification of unmanned aerial systems divides them into four categories; micro and mini unmanned aerial vehicles (MUAV), medium altitude long endurance UAVs (MALE), high altitude long endurance UAVs (HALE) and vertical take-off and landing UAVs (Grace, 2013).

During disaster prevention and management, micro and mini unmanned aerial vehicles can be used. In Britain, the fire service of West Midland has employed the use of an MUAV to make observations regarding the development of fires. The MUAV was used to provide vital information on the progress of fires through thermal imagery. High altitude long endurance UAVs are also used in disaster management. In January 2010, a HALE unmanned aerial vehicle was used during an earthquake in Haiti to capture high-resolution infrared photographs of the scale of the disaster (Grace, 2013). Medium altitude long endurance drones have been used in the management of disasters as well. In 2004, during the Tsunami a medium-altitude UAV was used to search for missing people (Austin, 2013). The prevention and management of disasters, the high endurance of the aircraft coupled with its ability to make observations over an expansive area, is important. This is especially important for rescue missions at sea. UAVs equipped with thermal cameras make it possible to locate victims buried in debris and avalanches.

Carrying out UAV missions during disaster prevention and management offers several advantages. The flexibility of UAVs makes them more effective than manned aircraft, especially during an earthquake whereby the downdraft from a manned helicopter may be strong enough to collapse an unstable building. The diminutive sizes of UAVs enable them to be flown in proximity to the zone of disaster without endangering the lives of rescuers or survivors (Fahlstrom & Gleason, 2013). A legal challenge during a UAS disaster management mission is with regards to restricted airspace. If the disaster occurs within restricted airspace, it poses a legal challenge to operate the drone in that area. An ethical challenge is that using a UAV in a search and rescue mission is that if a rescued victim requires immediate medical attention, he or she would have to wait for medical assistance to arrive, which may lead to more fatalities.  

References

Austin, R. (2013). Unmanned aircraft systems (1st ed.). Hoboken, N.J.: Wiley.

Fahlstrom, P. & Gleason, T. (2013). Introduction to uav systems (1st ed.). Hoboken, N.J.: Wiley.

Grace, R. (2013). The Design and Planning of Monitoring, Reporting, and Fact-Finding Missions. SSRN Electronic Journal. doi:10.2139/ssrn.2365435

4.4 - Research: UAS in the NAS

Monitoring and maintaining the unmanned aircraft in NAS (National Air Space)

 After its invention, the unmanned aircraft are still struggling to be accepted by the commercial aviation industry due to lack of security, monitoring and maintenance features.    One of the most discussed issues is the separation of the UAS (unmanned aircraft systems) in the national airspace for security reasons (Ramasamy, Sabatini & Gardi, 2014).   Till date, the use of the ADS-B (Automatic Dependent Surveillance-Broadcast) is considered as the most efficient way to monitor the movement of the UAS in certain airspace. This system is developed with the collaborative effort of the NASA and Modern Technology Solutions, Inc. Use of this ADS-B system will enable unmanned aircraft to collect information about the airspace.  The system will analyze the collected data to maintain a safe distance from the other manned or unmanned aircraft in the same airspace.

Considerations need to be made based on variation of sizes and airframes of UAS

 In the case of the smaller UAS group (1&2), this kind of aircraft are able to fly under the line of sight which helps it, operators, to manage its flight path while maintaining safe distance with the other manned or unmanned vehicle (Jeannin et al., 2015).  However, the capacity of these aircraft is less compared to other groups with respect to the integration of the sensory technology for separation.  Hence the ability to avoid the obstacles in the path without operator’s interference is very low.

On the contrary, the higher group (i.e. 3& 5) have better ability and capacity to integrate the sensory system that are important for the separation from the other manned and unmanned aircraft like the ADS-B or ACAS. The mentioned systems are also not error-free, this kind of sensory systems are affected by the latencies which happen due to the control data uplinks of the operator. Again, as the larger unmanned aircraft have increased the operational speed at the high altitudes, therefore this factor reduces their ability separate itself from the other manned or unmanned aircraft.

Different Technologies currently employed by manned aircraft

ACAS (Airborne Collision Avoidance Systems):  This technology is mainly designed to integrate to the manned aircraft for making necessary path adjustment of the flight (Jeannin et al., 2015).  This technology is now under research so that this can be integrated to the UAS that operates in the national airspace of the country.

ASAS (Airborne Separation Assistance Systems):   It is considered as an automatic broadcasting and surveillance system. It helps the unmanned aircraft in the airspace to have situational awareness so that the separation between the unmanned and manned aircraft can be easily done.

Cameras:  In most of the cases it is seen that cameras are integrated with the unmanned aircraft to view and avoid the obstacles, other aircraft by analyzing and processing the captured image by the wide-angle camera. 

TCAS II: One of the widely-used separation technology used for the manned aircraft. The traffic alert and collision avoidance system provides overall safety to the vehicles by providing alert to the pilot of the aircraft in order to avoid the collision with other aircraft in the same airs space (Ramasamy, Sabatini & Gardi, 2014).     

References

Jeannin, J. B., Ghorbal, K., Kouskoulas, Y., Gardner, R., Schmidt, A., Zawadzki, E., & Platzer, A. (2015, April). A formally verified hybrid system for the next-generation airborne collision avoidance system. In International Conference on Tools and Algorithms for the Construction and Analysis of Systems (pp. 21-36). Springer Berlin Heidelberg.

Sahawneh, L. R., Duffield, M. O., Beard, R. W., & McLain, T. W. (2015). Detect and Avoid for Small Unmanned Aircraft Systems Using ADS-B. Air Traffic Control Quarterly, 23(2-3), 203-240.

Ramasamy, S., Sabatini, R., & Gardi, A. (2014, May). Avionics sensor fusion for small size unmanned aircraft sense-and-avoid. In Metrology for Aerospace (MetroAeroSpace), 2014 IEEE (pp. 271-276). IEEE.

Zou, X., Alexander, R., & McDermid, J. (2016, June). On the Validation of a UAV Collision Avoidance System Developed by Model-Based Optimization: Challenges and a Tentative Partial Solution. In Dependable Systems and Networks Workshop, 2016 46th Annual IEEE/IFIP International Conference on (pp. 192-199). IEEE.