Fire rescue operations can be very demanding and dangerous to the people and equipment involved. Through the use of an unmanned aerial vehicles fire rescue personnel have the potential to utilize a valuable tool that allows them a birds eye view of the rescue scene. Thermal imaging allows for identification of hot spots within structure and locating people within burning buildings and homes. Such a technology becomes more critical when responding at night in the dark where visibility is limited.
The UAS must withstand various weather conditions, high temperatures, and supporting a variety of sensor payloads. Below are sample base requirements for the system and their respective derived requirements.
Air Vehicle system development design considerations cover such areas as maximum altitude, cruise speed, loiter speed, climb rate, radius of action, and hover capability. One of the key requirements needed by fire rescue personnel is the ability to circle or lock onto an object or structure and either orbit or hover to provide real time visual feedback.
1. Air Vehicle Element
1.1. Shall provide capability to orbit (i.e., fly in circular pattern around) or hover over an object of interest.
1.1.1. [Derived] Air Vehicle shall avoid obstacles when circling around object of interest
1.1.2. [Derived] Air Vehicle orbit radius shall be modifiable based on location.
1.1.3. [Derived] Air Vehicle hover altitude shall be modifiable based on location.
1.1.4. [Derived] Air Vehicle orbit shall automatically compensate for high temperatures above maximum threshold.
1.1.5. [Derived] Air Vehicle hover shall automatically compensate for high temperatures above maximum threshold.
1.1.6. [Derived] Air Vehicle orbit shall hold hover accuracy within twelve inches when winds reach up to 25 mph.
1.1.7. [Derived] Air Vehicle orbit shall hold hover accuracy within twelve inches when winds reach up to 25 mph.
Command and control is a critical interface needed for the receipt, processing, and transmission of information. Visual feedback requirements are critical to help with rescue decisions based on endangered life found within burning structure as well as hot spots that can’t be identified other than thermal imaging.
2. Command and Control (C2)
2.1. Shall visually depict payload sensor views
2.1.1. [Derived] C2 shall display high definition (720P) color live video feed when mode is selected.
2.1.2. [Derived] C2 shall display thermal imaging to identify hot spots versus life when mode is selected.
2.1.3. [Derived] C2 shall display sensor views on rugged Toughbook laptop.
2.1.4. [Derived] C2 Human machine interface for payload sensor views shall be designed per current human factors standards
The payload determines the capability of the vehicle and mission type. Modularity of payloads is a major advantage allowing for greater versatility and environments. Size, weight, power consumption, and cost are key payload characteristics that need to be taken into consideration during system development.
3. Payload
3.1. Shall use power provided by air vehicle element
3.1.1. [Derived] Payload shall be provided power by the air vehicle for up to 2 hours.
3.1.2. [Derived] Payload shall notify/communicate to operator when power requirements are at a minimum due to system issue.
3.1.3. [Derived] Payload air vehicle power should have a back up redundant system so landing is not required for troubleshooting.
Data link communications involves range, missions, deployment area, availability of frequencies, and operational cost. The radius of action of the air vehicle is an import factor contributing to the usefulness of the system being developed. Determining whether the system will be flown within line of sight or beyond line of sight must be known early on in the system development.
4. Data-Link
4.1. Shall be capable of communication range exceeding two miles visual line of site (VLOS).
4.1.1. [Derived] Data-Link shall be impermeable to radio signal interference when beyond line of sight.
4.1.2. [Derived] Data-Link uplink/downlink signal shall not degrade when at a distance of two miles.
4.1.3. [Derived] Data-Link shall operator on a standard frequency that is secure.
Testing requirements are required to verify the derived requirements are met or exceeded.
5. Testing Requirements
5.1. Air Vehicle
5.1.1. Performance Accuracy
5.1.1.1. Verify hover capability minimum position requirement is met
5.1.1.2. Verify orbit capability minimum position requirement is met
5.1.1.3. Verify when position modification is made during orbit vehicle adjusts accordingly
5.1.1.4. Verify vehicle adjusts orbit when maximum temperature is reached
5.1.1.5. Verify vehicle adjusts hover when maximum temperature is reached
5.2. Command and Control
5.2.1. Reliability
5.2.1.1. Verify high definition video feed functions during flight without signal loss
5.2.1.2. Verify thermal imaging video mode functions properly during flight.
5.2.1.3. Verify C2 communication and interface between Toughbook and air vehicle
5.2.1.4. Verify HMI is user friendly and intuitive for operator.
5.3. Payload
5.3.1. Functionality
5.3.1.1. Verify maximum power requirements of air vehicle during flight
5.3.1.2. Verify minimum power requirements of air vehicle during flight.
5.3.1.3. Verify redundant back up system functions when air vehicle power can not supply payload power
5.3.1.4. Verify user message/alarm when power reduction/failure occurs.
5.4. Data Link
5.4.1. Reliability
5.4.1.1. Test air vehicle communication using standard forms of radio interference to verify system is not compromised
5.4.1.2. Test flight of air vehicle at pre-determined distance intervals to meet communication requirements when beyond line of sight.
The system development sample requirements outlined above would require the 10-phase waterfall method, which would start with the concept design and research leading to design, test, development, certification, production, and support. The purpose of using this method is due to tight control of requirements, documentation, and formal gate reviews. The system development methodology also allows for tight control of schedule and cost. The fire rescue drone would use common off the shelf components allowing for the budget to be met within the nine month scheduled project. Ground testing would also involve component and subsystem testing due to the harsh environments the vehicle would encounter. Temperature, wear, functionality, strength, fatigue, and acceleration are all key characteristic that would require baseline data. Subsystem testing would require verification of the flight control system, power plant, and payloads under simulated flight conditions at a minimum.
References:
Austin, R. (2010). Unmanned aircraft systems: UAVS design, development, and deployment. Chichester, West Sussex, U.K: Wiley.
AndyGurd. (2013, January 28). Managing your requirements 101 –A refresher. Part 4: What is traceability? [Web log post]. Retrieved from https://www.ibm.com/developerworks/community/blogs/requirementsmanagement/entry/managing_your_requirements_101_a_refresher_part_4_what_is_traceability7?lang=en
Saturday, February 27, 2016
Sunday, February 21, 2016
UAS Missions
Unmanned aerial vehicle mission types are now capable of civil and military uses not previously possible due to platform technology advancements. The design and implementation processes is based on mission and environment while remaining requirements driven. As applications for UAS missions increase the design and implementation challenges grow exponentially.
A potential UAS civil mission type that would provide a distinct advantage over current methods would be infrastructure inspection such as bridges and power lines. Currently such inspections are carried out using humans as the inspector either by climbing the structure to be inspected or using a helicopter to drop the person off on the infrastructure requiring inspection. Both methods are extre3mly costly and dangerous. The use of an unmanned aerial system would eliminate the unsafe human factor allowing a more detailed inspection as well as photos and videos that could be analyzed at a later time determining if actual repair work is required.
The mission type would require a platform with hover capability in order to inspect structure at various heights and environments. Platforms that would allow the hover capability would be a quadcotper/multi rotor, co-axial rotor, and a ducted fan which would allow for more leniency when bumping into objects or structure (CALTRANS, 2008). The most effective design would be the quad copter or co-axial rotor due to simplicity and size of the design as well as the potential for using lightweight electric motors for propulsion which helps reduce cost (Unmanned Aerial, 2015). The electric motors would have an electronic speed controller allowing for precise algorithms to be used in flight maneuverability, stability, and control. Wind and weather would be a concern as well due to flying near water over bridges and higher altitudes necessary to inspect high power transmission lines without making contact or colliding. Lightweight design coupled with a precise autopilot controller would be necessary as well as weather proofing the entire vehicle.
The UAS would require various sensors for precise collision avoidance as to not collide with structure being inspected. This could be accomplished with ultrasonic sensors or lasers. The main payload sensor would be the camera equipment for inspection which would also send a live video feed back to the operator/pilot. All data would be recorded for later analysis. The system would also require the ability to hold position via GPS but also an inertial navigational system utilizing an IMU if signal is lost when structure obstructs or reduces signal strength. Another option for more difficult inspection mission types would be to have two UAV’s. One for the actual inspection and one that flies at a specified distance away but trails behind to allow for the signal strength to remain strong regardless of location or position. Basically a flying antennae. The two UAV design and implementation option would be more costly but utilized in more specialized inspection mission types where signal relay is critical.
Line of sight requirements would be a challenge due to needing to inspect beneath structure that could be over water. Also the times at which this inspection would take place would be a challenge if inclement weather were to persist or if high winds are common in an area requiring inspection. Also making sure not to distract passersby’s or bridge traffic during inspection.
As mission types grow utilizing UAS’s obstacles will need to be overcome. However there are many applications for UAV’s currently that either reduce or eliminate the human factor risk making UAS mission types more valuable than ever.
References
Unmanned Aerial, 2015. State DOT: How Can UAV’s Aid in Bridge Inspections. Retrieved from http://unmanned-aerial.com/state-dot-how-can-uavs-aid-in-bridge-inspections/
Mennesota DOT, 2015. Unmanned Aerial Vehicle Bridge Inspection Demonstration Project. Retrieved from http://www.dot.state.mn.us/research/TS/2015/201540.pdf
CALTRANS, 2008. Bridge Inspection Aerial Robot Final Report. Retrieved from http://www.dot.ca.gov/newtech/researchreports/reports/2008/08-0182.pdf
A potential UAS civil mission type that would provide a distinct advantage over current methods would be infrastructure inspection such as bridges and power lines. Currently such inspections are carried out using humans as the inspector either by climbing the structure to be inspected or using a helicopter to drop the person off on the infrastructure requiring inspection. Both methods are extre3mly costly and dangerous. The use of an unmanned aerial system would eliminate the unsafe human factor allowing a more detailed inspection as well as photos and videos that could be analyzed at a later time determining if actual repair work is required.
The mission type would require a platform with hover capability in order to inspect structure at various heights and environments. Platforms that would allow the hover capability would be a quadcotper/multi rotor, co-axial rotor, and a ducted fan which would allow for more leniency when bumping into objects or structure (CALTRANS, 2008). The most effective design would be the quad copter or co-axial rotor due to simplicity and size of the design as well as the potential for using lightweight electric motors for propulsion which helps reduce cost (Unmanned Aerial, 2015). The electric motors would have an electronic speed controller allowing for precise algorithms to be used in flight maneuverability, stability, and control. Wind and weather would be a concern as well due to flying near water over bridges and higher altitudes necessary to inspect high power transmission lines without making contact or colliding. Lightweight design coupled with a precise autopilot controller would be necessary as well as weather proofing the entire vehicle.
The UAS would require various sensors for precise collision avoidance as to not collide with structure being inspected. This could be accomplished with ultrasonic sensors or lasers. The main payload sensor would be the camera equipment for inspection which would also send a live video feed back to the operator/pilot. All data would be recorded for later analysis. The system would also require the ability to hold position via GPS but also an inertial navigational system utilizing an IMU if signal is lost when structure obstructs or reduces signal strength. Another option for more difficult inspection mission types would be to have two UAV’s. One for the actual inspection and one that flies at a specified distance away but trails behind to allow for the signal strength to remain strong regardless of location or position. Basically a flying antennae. The two UAV design and implementation option would be more costly but utilized in more specialized inspection mission types where signal relay is critical.
Line of sight requirements would be a challenge due to needing to inspect beneath structure that could be over water. Also the times at which this inspection would take place would be a challenge if inclement weather were to persist or if high winds are common in an area requiring inspection. Also making sure not to distract passersby’s or bridge traffic during inspection.
As mission types grow utilizing UAS’s obstacles will need to be overcome. However there are many applications for UAV’s currently that either reduce or eliminate the human factor risk making UAS mission types more valuable than ever.
References
Unmanned Aerial, 2015. State DOT: How Can UAV’s Aid in Bridge Inspections. Retrieved from http://unmanned-aerial.com/state-dot-how-can-uavs-aid-in-bridge-inspections/
Mennesota DOT, 2015. Unmanned Aerial Vehicle Bridge Inspection Demonstration Project. Retrieved from http://www.dot.state.mn.us/research/TS/2015/201540.pdf
CALTRANS, 2008. Bridge Inspection Aerial Robot Final Report. Retrieved from http://www.dot.ca.gov/newtech/researchreports/reports/2008/08-0182.pdf
Saturday, February 6, 2016
UAS in the NAS
Separation of unmanned aerial vehicles in the national airspace continues to be an area not fully addressed causing delays in regards to the integration of UAS in NAS by the FAA. Mid air collisions still occasionally occur with manned aircraft more specifically in general aviation as seen most recently over the harbor in Los Angeles (Serna, J. 2016). Making the transition and having confidence in technology for sense and avoidance and separation once the pilot is removed from the cockpit is a huge leap that has been undertaken for some time now but without complete success, yet. Sense and avoid technologies currently are listed by the FAA as one of the top reasons for not meeting the deadline for UAS integration in the NAS in addition to data link and control station reliability, lack of air traffic control procedures, minimum air vehicle performance requirements, and inadequate framework for sharing and analyzing safety data (Hampton, M. 2014).
There are various sensor and sensing options currently available such as ADS-B which will be required on all transport aircraft by 2020 per the ongoing NextGen efforts that uses GPS to broadcast aircraft position and velocity in an accurate manner. ATC transponders which most aircraft carry is another method for tracking an aircrafts location based on interrogation of ground based radar which is a much older technology that’s been in use for years but has many shortcomings. Transponders and ADS-B only work if an air vehicle is equipped with them otherwise non-cooperative traffic would not be detectable. Other sensing technologies outside of the two most common are infrared cameras, primary radar, laser range finding, and acoustic processing (Angelov, P. P. 2012). Another issue arises based on group number. Smaller UAV’s found in group 1 and 2 may not be capable of being outfitted with a multitude of sensors due to weight and power restrictions. Regardless of group in order for SAA systems to be certifiable and successful in the NAS five key sensor parameters must be accounted for based on UAV type and environment. Filed of view, range, update rate, accuracy, and integrity are the critical components in a UAV sensing system that are currently being tested by various research groups such as the DoD, DARPA, and NASA (Angelov, P. P. 2012). The second element is the avoid aspect which involves threat identification and resolution. Collision avoidance involves the use of algorithms to determine the distance and space to maneuver to avoid a potential threat. Based upon airframe configuration the time in which an air vehicle must avoid a threat will be different. An electric multi rotor copter versus a fixed wing twin turbo fan would approach each other at very different speeds making threat identification and resolution decisions occur at different rates. Even with ongoing testing, we are still not at the point of seamless integration and the FAA still needs to set clear and concise standards.
Current technologies coupled with more advanced techniques could provide a solution for UAS integration but I believe using a technology like TCAS or ADS-B alone on a UAV would be oversimplifying the issue. More test data is required for confidently certifying a sense and avoid system or self-separation standard. Although the military has many UAV flight hours of experience the majority of time is spent flying in remote or desolate locations, not in our busy national airspace where traffic density continues to increase.
References
Angelov, P. P., & Books24x7, I. (2012). Sense and avoid in UAS: Research and
applications (2nd;1; ed.). Hoboken: John Wiley & Sons.
Austin, R. (2010). Unmanned aircraft systems: UAVS design, development,and deployment. Chichester, U.K: John Wiley & Sons Ltd.
Hampton, M. (2014). FAA’s Progress and Challenges in Integration of Unamanned Aircraft
Retrieved from
http://transportation.house.gov/uploadedfiles/2014-12-10-hampton.pdf
Serna, J. (2016). Mid Air Collsion off Coast Near LA Harbor. Retrieved from,
http://www.latimes.com/local/lanow/la-me-ln-la-harbor-plane-crash-20160205-story.htmlthe NAS.
There are various sensor and sensing options currently available such as ADS-B which will be required on all transport aircraft by 2020 per the ongoing NextGen efforts that uses GPS to broadcast aircraft position and velocity in an accurate manner. ATC transponders which most aircraft carry is another method for tracking an aircrafts location based on interrogation of ground based radar which is a much older technology that’s been in use for years but has many shortcomings. Transponders and ADS-B only work if an air vehicle is equipped with them otherwise non-cooperative traffic would not be detectable. Other sensing technologies outside of the two most common are infrared cameras, primary radar, laser range finding, and acoustic processing (Angelov, P. P. 2012). Another issue arises based on group number. Smaller UAV’s found in group 1 and 2 may not be capable of being outfitted with a multitude of sensors due to weight and power restrictions. Regardless of group in order for SAA systems to be certifiable and successful in the NAS five key sensor parameters must be accounted for based on UAV type and environment. Filed of view, range, update rate, accuracy, and integrity are the critical components in a UAV sensing system that are currently being tested by various research groups such as the DoD, DARPA, and NASA (Angelov, P. P. 2012). The second element is the avoid aspect which involves threat identification and resolution. Collision avoidance involves the use of algorithms to determine the distance and space to maneuver to avoid a potential threat. Based upon airframe configuration the time in which an air vehicle must avoid a threat will be different. An electric multi rotor copter versus a fixed wing twin turbo fan would approach each other at very different speeds making threat identification and resolution decisions occur at different rates. Even with ongoing testing, we are still not at the point of seamless integration and the FAA still needs to set clear and concise standards.
Current technologies coupled with more advanced techniques could provide a solution for UAS integration but I believe using a technology like TCAS or ADS-B alone on a UAV would be oversimplifying the issue. More test data is required for confidently certifying a sense and avoid system or self-separation standard. Although the military has many UAV flight hours of experience the majority of time is spent flying in remote or desolate locations, not in our busy national airspace where traffic density continues to increase.
References
Angelov, P. P., & Books24x7, I. (2012). Sense and avoid in UAS: Research and
applications (2nd;1; ed.). Hoboken: John Wiley & Sons.
Austin, R. (2010). Unmanned aircraft systems: UAVS design, development,and deployment. Chichester, U.K: John Wiley & Sons Ltd.
Hampton, M. (2014). FAA’s Progress and Challenges in Integration of Unamanned Aircraft
Retrieved from
http://transportation.house.gov/uploadedfiles/2014-12-10-hampton.pdf
Serna, J. (2016). Mid Air Collsion off Coast Near LA Harbor. Retrieved from,
http://www.latimes.com/local/lanow/la-me-ln-la-harbor-plane-crash-20160205-story.htmlthe NAS.
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