To date,many studies related to robots have been performed around the world.Many of these studies have assumed operation at locations where entry is difficult,such as disaster sites,and have focused on various terrestrial robots,such as snake-like,humanoid,spider-type,and wheeled units.Another area of active research in recent years has been aerial robots with small helicopters for operation indoors and outdoors.However,less research has been performed on robots that operate both on the ground and in the air.Accordingly,in this paper,we propose a hybrid aerial/terrestrial robot system.The proposed robot system was developed by equipping a quadcopter with a mechanism for ground movement.It does not use power dedicated to ground movement,and instead uses the flight mechanism of the quadcopter to achieve ground movement as well.Furthermore,we addressed the issue of obstacle avoidance as part of studies on autonomous control.Thus,we found that autonomous control of ground movement and flight was possible for the hybrid aerial/terrestrial robot system,as was autonomous obstacle avoidance by flight when an obstacle appeared duringground movement.