Unmanned system applications apply to air, ground, space, and maritime operational domains. In this post, the idea of combining systems from separate operational domains is discussed. We will focus on Yu Wu's research into the future of an unmanned aerial-aquatic vehicle (UAAV)-autonomous underwater vehicle (AUV) system coordination, working together on an underwater target strike mission.
UAAVs in Development
Before diving into Yu Wu's research, here is some background on UAAVs. This technology is incredibly new and, therefore, not yet able to tackle the air and sea, completely, just yet. The idea behind UAAVs is to expand on the capabilities of unmanned aerial systems (UASs).
A team at Johns Hopkins University created the Flying Fish in 2017. The Flying Fish operates in both aerial and underwater applications. Over the course of 30 months, using a single motor and propeller, Joe Moore, Eddie Tunstel, and Robert Osiander developed this vehicle to slow its propeller as it descends into the water, with prop speed increasing as it rises back to the air. In the long-run, these researchers aim for 30mph (48kmh) autonomous flight with the capability of collecting data from air and water before returning to base (Intelligent Systems Center, 2017).
Imperial College London created the Aquatic Micro Air Vehicle (AquaMAV) where plunge diving, folding wings, and water jet propulsion all allow the device to fly and swim (Aerial Robotics Lab, n.d.).
Oakland University produced Loon Copter - an amphibious multicopter drone which is capable of aerial flight, surface operations, and diving (Oakland University..., n.d.).
Outside of UAAVs, there are currently no articles describing the coordination of UAAVs and AUVs. As these UAAVs develop, is there a future where these systems can handle Wu's proposal all on their own, or has Yu Wu provided a stepping-stone for the meantime operations until these UAAV systems are capable of deeper applications?
For the nature of this blog post, Yu Wu's research will be incredibly simplified, though it is highly recommended you read his paper in its entirety - it is fascinating.
Wu suggests that the target strike mission be broken into two phases: the aerial operations of the UAAV and the underwater coordination between both systems. UAAV capabilities allow for a faster reconnaissance option with less obstacles. As the UAAV searches, the AUV remains motionless until it is given a command to follow closely behind by way of the particle swarm optimization (PSO) algorithm. Once recon data is collected, the UAAV then dives towards the AUV for close-distance data transfer in recognition of security risks associated with such distance and sensitive information. Having this new information, and translated into data privy to its underwater location, the AUV can then more quickly search for said target. Once the target is located, both the AUV and the UAAV can strike, simultaneously (Wu, 2019). This adds a third capability to this coordinated system: multi-directional strikes.
UAAVs are still in their infancy. If we compare the technology required for the operation of UASs and unmanned maritime vehicles (UMVs), current UAAVs have a long way to go before they can compare. However, Yu Wu presents a stepping-stone between this new technology and a likely future where one system can handle air and sea on its own.
Yu Wu's research is currently absolutely necessary, in my opinion, as it provides a way for these systems to search for underwater targets in a way that alleviates the AUV's work, which has the very real potential to shorten the lifespan of these missions. Time is money, time can cost lives and diminish resources. Therefore, though a future with UAAVs flying through the air and diving to the depths of the ocean floor is a very real possibility, this is a current opportunity to solve the underwater target search problem faster.
Using two systems does come with a cost, though. Depending on the location (ocean, lake, river), a surface vessel may be responsible for the storage and operation of both the UAAV and AUVs. This means more space taken on the vessel and more personnel needed to get the job done. However, with the potential to shorten the lifespan of the target strike mission, these resources won't be needed for the same time-span current missions require. Funding is also another issue in order to access and use two systems. This cost, though, will again be offset by missions taking less time.
To put it simply, a future where one system can accomplish aerial and underwater tasks is very likely coming. Currently, that is not possible, so the coordinated efforts of two systems from two operational domains (where one has the potential to overlap) can greatly reduce time spent on a single mission.
Aerial Robotics Lab (n.d.). The AquaMAV project. Retrieved from https://www.imperial.ac.uk/aerial-robotics/research/aquamav/
Intelligent Systems Center (2017). Flying Fish unmanned aerial-aquatic vehicle (UAAV) from APL. Retrieved from https://www.jhuapl.edu/ISC/Home/NewsItem/11
Oakland University Embedded Systems Research Laboratory (n.d.). Loon Copter. Retrieved from www.looncopter.com
Wu, Y. (2019). Coordinated path planning for an unmanned aerial-aquatic vehicle (UAAV) and an autonomous underwater vehicle (AUV) in an underwater target strike mission. Ocean Engineering, 182, 162 - 173. doi.org/10.1016/j.oceaneng.2019.04.062