Aerial-aquatic robots: non-adaptive designs - 7 Flashcards
What are unmanned aerial-aquatic vehicles (UAAVs)?
A multi-modal robot that can operate in two modes: air and water.
Give an example of an application for a UAAV.
Oil spill monitoring, water health, coral reef monitoring, marine investigation, splash zone diagnostics, industrial maintenance, arctic sea sampling, flooding response, disaster relief or underwater inspection.
What challenges are involved in designing and operating UAAVs?
Conflicting requirements for aerial and underwater operation, water state is chaotic and unpredictable, so robust transition and control are required, dependence on wind and weather, underwater communication limitations.
Name two different design approaches that are used to develop UAAVs.
Adapt existing configurations (multirotor, fixed-wing), unconventional designs (flapping-wing) or adaptive / morphing designs.
What are the benefits and limitations of adapting, respectively, (i) multirotors and (ii) fixed-wing MAVs for aquatic operations?
(i) Are simple, robust, and highly maneuverable, but endurance and waterproofing as well as communication, are hard
(ii) Easier to ensure stability for both modes with better performance and endurance but less maneuverable and need for robust control to maintain stability in the transition
Explain the two main transition approaches used for aerial-aquatic multirotors. What are their respective
challenges and benefits?
Static: using a ballast system to adjust the buoyance and dynamic: use propellers to force vehicle underwater and pull it out again.
Dynamic: good control of the transition phase but consumes significant power to maintain underwater stability and change depth.
Static: depth control is easy due to the ballast system and has great underwater stability. More mass needed for the system which reduces air time flight capabilities
Why are multirotors typically re-oriented when operating underwater?
Multirotors are typically re-oriented when operating underwater to reduce power requirements and improve stability. The tilt ensures that the rotors are horizontal, reducing the power needed for underwater operation.
Explain the two main transition approaches used for fixed-wing UAAVs. What are their respective
challenges and benefits?
For fixed-wing UAAVs, the two main transition approaches are impulsive and gradual. The impulsive approach involves rapidly releasing much energy for a quick transition robust to waves with minimal control but requires significant power and its less reliable. The gradual approach, such as thrust vectoring, allows for repeated transitions but requires robust control to maintain stability as well as more dependent on sea state.
Explain the concept of water-jetting for UAAV water exit.
The concept of water-jetting for UAAV water exit involves the rapid release of a large amount of energy, typically through the expulsion of a high-pressure water jet. This provides a large amount of thrust that propels the UAAV out of the water. Very high acceleration in a very short time with large forces.
How do waves influence UAAV take-off? What types of waves are typically the most dangerous?
They affect orientation and stability. Robots can deal with small or slow waves, but robot cannot deal with large or rapid waves, making them the most dangerous.
