  In this research, we investigated the innovative use of a manipulator as a
tail in quadruped robots to augment their physical capabilities. Previous
studies have primarily focused on enhancing various abilities by attaching
robotic tails that function solely as tails on quadruped robots. While these
tails improve the performance of the robots, they come with several
disadvantages, such as increased overall weight and higher costs. To mitigate
these limitations, we propose the use of a 6-DoF manipulator as a tail,
allowing it to serve both as a tail and as a manipulator. To control this
highly complex robot, we developed a controller based on reinforcement learning
for the robot equipped with the manipulator. Our experimental results
demonstrate that robots equipped with a manipulator outperform those without a
manipulator in tasks such as rapid turning, aerial reorientation, and
balancing. These results indicate that the manipulator can improve the agility
and stability of quadruped robots, similar to a tail, in addition to its
manipulation capabilities.
