  Exploiting contacts with environment structures provides extra force support
to a UAV, often reducing the power consumption and hence extending the mission
time. This paper investigates one such way to exploit flat surfaces in the
environment by a novel aerial-ground hybrid locomotion. Our design is a single
passive wheel integrated at the UAV bottom, serving a minimal design to date.
We present the principle and implementation of such a simple design as well as
its control. Flight experiments are conducted to verify the feasibility and the
power saving caused by the ground locomotion. Results show that our minimal
design allows successful aerial-ground hybrid locomotion even with a
less-controllable bi-copter UAV. The ground locomotion saves up to 77% battery
without much tuning effort.
