  Bilateral teleoperation provides humanoid robots with human planning
intelligence while enabling the human to feel what the robot feels. It has the
potential to transform physically capable humanoid robots into dynamically
intelligent ones. However, dynamic bilateral locomotion teleoperation remains
as a challenge due to the complex dynamics it involves. This work presents our
initial step to tackle this challenge via the concept of wheeled humanoid robot
locomotion teleoperation by body tilt. Specifically, we developed a
force-feedback-capable whole-body human-machine interface (HMI), and designed a
force feedback mapping and two teleoperation mappings that map the human's body
tilt to the robot's velocity or acceleration. We compared the two mappings and
studied the force feedback's effect via an experiment, where seven human
subjects teleoperated a simulated robot with the HMI to perform dynamic target
tracking tasks. The experimental results suggest that all subjects accomplished
the tasks with both mappings after practice, and the force feedback improved
their performances. However, the subjects exhibited two distinct teleoperation
styles, which benefited from the force feedback differently. Moreover, the
force feedback affected the subjects' preferences on the teleoperation
mappings, though most subjects performed better with the velocity mapping.
