The Search for a Marine Search and Rescue UAS

Introduction

Executives of a small start-up Embry-Eagle Rescue (EER) are seeking information on the best unmanned aerial system (UAS) for use in marine search and rescue missions.  The following paper is an evaluation and recommendation of the best possible UAS for such search and rescue missions.  This paper will examine one particular type of vehicle that is recommended to the firm for further consideration. 

This paper will be divided into six sections.  The current section is the introduction and sets out the main goals for the paper.  Section two will provide a brief background on the uses of UAV to further flesh out the uses for such devices.  Section three will evaluate available types of UAV based on a review of the relevant literature. Section four will discuss the best possible UAV from among the options discovered in the research. The fifth section is the summary and conclusion. 

Background

UAVs are being increasingly used to perform tasks, for both civilian and military purposes, where it is particularly dangerous to send manned vehicles.  Among civilian-specific search and rescue uses are: Searching for individuals lost in wilderness areas and guiding them to a safe location; Searching at sea assistance in which the UAVs may also drop supplies to stranded parties; and assistance in disaster emergencies such as earthquakes, flooding and forest fires (Doherty, Kvarnstrom, Heintz, Landen, & Olsson 2010).  UAVs equipped with cameras can provide aerial coverage of specific or targeted areas with real time images sent back to a base station for further review.  The US military uses such vehicles for stealth reconnaissance missions on both land and sea (Austin, 2010).  

The technology that is used to operate UAVs can allow for both a form of autonomous intelligence or for manual joystick remote control at a base station.  The more sophisticated software involves a number of component algorithms which are integrated to give the vehicles the capacity for autonomous operation (Doherty et al., 2010; Xu, Viriyasuthee, & Rekleitis, 2011).  UAV operation usually involves two functions: a pilot who controls the UAV by remote and a sensor operator.  The sensor operator will analyze sensor inputs (Lin, Roscheck, Goodrich, & Morse 2010).

UAVs, in search and rescue operations, are deployed using multiple vehicles in which coordination with the base station is crucial.  Multiple vehicles allow a large coverage area to be searched simultaneously.  But multiple vehicles may also be required where low fuel capacity or limited communication ranges are a problem.  To mitigate this, multiple vehicles are used either as a back-up option or deployed as part of relay systems to bridge communications with the base (Doherty et al., 2010).  

Task Description

The product specifications for the mission include the ability of the UAV to function under surface winds of up to 75 mph.  The device must also have a tolerance for temperatures between -10 and 40 degrees Celsius.  Particular emphasis is placed on the military drones' ability to detects boats in water of minimum of 22' in length.  Ideally it should also be able to function at seas of 30'.  Thus the ideal UAS is one that will be effective for the particular demands of marine rescue in the Pacific Ocean. The specific coverage area will be between 100 and 1500 miles from Honolulu, HI. 

Evaluating Types of UAV Options

The review of the literature found that the bulk of the models appeared to be primed for two different sets of operations.  The first is a military function that involved stealth and non-stealth reconnaissance missions (Austin, 2010).  The second is a civilian function aimed at land-based or wilderness search and rescue tasks (WiSR) (Lin et al., 2010).  Neither of these functions are thought to be appropriate to the specific task at hand which involved UAV platforms specific to marine search and rescue milieus.  It is possible to adapt one of these military or civilian vehicles to the particular task under consideration. However, it is likely that the outcomes may not be satisfactory.  

The literature does report a wide array of vehicles or devices that are used in WiSR.  Yet owing to the differences in terrain, flight altitude and atmospheric conditions, these types of vehicles were not considered suitable options.  Such vehicles types include: the Draganfly V Ti Pro R/C helicopters tested on MIT's RAVEN platform (Bethke, Valenti, & How 2010), The UASTech LinkQuad Quadrotor Helicopter, The UASTech RMAX, LinkMAV, and the PingWing all of which were tested in another study (Doherty et al., 2010).  Each of these vehicles is focused primarily on ground terrain and forested areas.  Thus neither of these were thought to have the design features suitable to a marine environment. The next section discusses what is likely the closest available such vehicle at the present time. 

UAV Recommendation

Unfortunately, a vehicle that best fits the parameters of the task proved to be difficult the find.  The closest possible match is a vehicle prototype under development three years ago by the EUREKA E! 3931 ASARP project ("Shape-shifting" 2010; Coxworth 2010).  It should be noted that ASARP is an acronym for Airborne Search and Rescue Platform.  EUREKA is a European intergovernmental network that supports and funds research and development with a market oriented focus ("Shape-shifting" 2010; Coxworth 2010).  

Eureka's prototype, which is pictured in figures 1 (front view) and 2 (rear view) below, was designed specifically for stormy sea rescues.  These kinds of rescues are particularly hazardous, for both the crew and the aircraft, to conduct using manned helicopters or fixed wing aircraft (Coxworth 2010).  The relevant characteristics of the seaplane are its ability to change shape.  This ability makes it adaptable to rough atmospheric conditions, such as high velocity winds. The prototype is able to launch and land from either ground or water ("Shape-shifting" 2010; Coxworth 2010).  It also has the capacity to maintain flight for up to 4.5 hours.  This could be a great plus for vehicles that are needed to survey a large coverage area such as the 1500 mile radius around Honolulu.  Multiple vehicles could be deployed to survey both northern and southern sections of the aforementioned coverage area simultaneously.  The vehicle has cameras which can transmit a live feed back to the base station where a human commander "pilots" the vehicle.  The prototype can't execute rescues, per se, but it can provide precise locations of stranded parties.  It's 88 lbs. payload means it can also ferry and drop supplies as needed ("Shape-shifting" 2010; Coxworth 2010). 

The E!3931's resistance to high velocity winds is a particularly relevant feature.  This resistance is developed from three aeroservoelastic trim tabs ("Shape-shifting" 2010; Coxworth 2010).  These tabs are located on the trailing edges of the wings and tail.  Thus when the seaplane experiences high velocity winds, the tabs will adapt by performing high frequency shape changes ("Shape-shifting" 2010; Coxworth 2010).  These changes enable the craft to counteract the resistance provided by strong gusts.  The technology used in the aeroservoelastic trim tabs is similar to that used to protect giant wind turbines from powerful wind gusts. The craft also has a special aerofoil profile which optimizes it for high lift at low speeds (Coxworth 2010). 

Unfortunately, there is not a lot of information available about this prototype currently.  According to the literature the vehicle was in the final stages of testing on Cyprus (Coxworth 2010).  However, recent searches have not turned a lot of new information such as where or when the seaplane was being deployed.  The project was being coordinated by GGD Engineering of Scotland. If EER management is interested in proceeding GGD could be queried for further information.  

Conclusion

In sum, the vehicle shows promise although how well it matches specific product specifications is not precisely known. That is, specific wind speeds and surveillance ranges are not yet known as of this writing.  Still the vehicle is designed for the specific atmospheric conditions requested, can be used specifically for marine search and rescue, and has a high fuel capacity and payload that it should be of great assistance to any search and recovery missions.

(Figure 1 & 2 omitted for preview. Available via download)

References

Austin, R. (2010). Unmanned Aircraft Systems: UAVs Design, Development And Deployment.  West Sussex, UK: John Wiley & Sons. Retrieved from http://rahauav.com/Library/Unmanned%20Vehicles/Unmanned-Air-Systems%28www.RahaUAV.com%29.pdf.  Sept. 2013. 

Doherty, P., J. Kvarnstrom, F. Heintz, D. Landen, & P-M. Olsson. (2010). Research with collaborative unmanned aircraft systems. Ida.liu.se. Retrieved from http://www.ida.liu.se/divisions/aiics/publications/DAGSTUHL-2010-Research-Collaborative-Unmanned.pdf.  Sept. 2013. 

Bethke, B., Mario V., & How, J. P. (2010, Mar.). Experimental demonstration of UAV task assignment with integrated health monitoring.  IEEE Robotics Automation Magazine.  Retrieved from http://vertol.mit.edu/papers/ram-hm-07.pdf.  Sept. 2013. 

Coxworth, B. (2010, Aug. 27). Shape-shifting UAV designed for stormy sea rescues. Gizmag.com. Retrieved from http://www.gizmag.com/shape-shifting-marine-rescue-uav/16161/picture/119722.  Sept. 2013.

Lin, L., Roscheck, M., Goodrich, M. A., & Morse, B. S. (2010). Supporting wilderness search and rescue with integrated intelligence: Autonomy and information at the right time and the right place. Aaai.org. 

Shape-shifting robot plane offers safer alternative for maritime rescue. (2010, Sept. 16). Sciencedaily.com.  Retrieved from http://www.sciencedaily.com/releases/2010/08/100826103835.htm.  Sept. 2013. 

Xu, A., Viriyasuthee, C., & Rekleitis, I. (2011, May). Optimal complete terrain coverage using an unmanned aerial vehicle. In Robotics and Automation (ICRA), 2011 IEEE International Conference, 2513-2519. Retrieved from http://www.cim.mcgill.ca/~mrl/pubs/anqixu/icra2011_optcov.pdf.  Sept. 2013.