Unmanned aerial-underwater vehicles (UAUVs) provide the potential for working on missions in complex multidomain environments. To achieve amphibian mobility, current UAUV designs rely on additional mechanical components such as multiple layers of propeller blades, water ballast, buoys or wings. This paper presents a miniature UAUV which has a simple mechanical design that resembles a traditional quadcopter. The paper discusses the dynamic modelling, state estimation and control strategy for this UAUV, as well as a detailed characterization of the quadcopter blades operating in the air and water regimes. A strategy for the UAUV to breach calm water surface is then proposed and experimentally tested. The results demonstrate that the UAUV can successfully breach the still water surface, but also show tracking error and breaching delay that are not fully characterized by the model. This suggests the need to carry out further analysis on the dynamics of the UAUV both underwater and in the transition regime.

We present the tensegrity aerial vehicle, a design of collision-resilient rotor robots with icosahedron tensegrity structures. The tensegrity aerial vehicles can withstand highspeed impacts and resume operation after collisions. To guide the design process of these aerial vehicles, we propose a modelbased methodology that predicts the stresses in the structure with a dynamics simulation and selects components that can withstand the predicted stresses. Meanwhile, an autonomous re-orientation controller is created to help the tensegrity aerial vehicles resume flight after collisions. The re-orientation controller can rotate the vehicles from arbitrary orientations on the ground to ones easy for takeoff. With collision resilience and re-orientation ability, the tensegrity aerial vehicles can operate in cluttered environments without complex collision-avoidance strategies. Moreover, by adopting an inertial navigation strategy of replacing flight with short hops to mitigate the growth of state estimation error, the tensegrity aerial vehicles can conduct short-range operations without external sensors. These capabilities are validated by a test of an experimental tensegrity aerial vehicle operating with only onboard inertial sensors in a previously-unknown forest.

Aerial vehicles with collision resilience can operate with more confidence in environments with obstacles that are hard to detect and avoid. This paper presents the methodology used to design a collision resilient aerial vehicle with icosahedron tensegrity structure. A simplified stress analysis of the tensegrity frame under impact forces is performed to guide the selection of its components. In addition, an autonomous controller is presented to reorient the vehicle from an arbitrary orientation on the ground to help it take off. Experiments show that the vehicle can successfully reorient itself after landing upside-down and can survive collisions with speed up to 6.5m/s.