  Mobile manipulators can be used for machine tending and material handling
tasks in small volume manufacturing applications. These applications usually
have semi-structured work environment. The use of a fully autonomous mobile
manipulator for such applications can be risky, as an inaccurate model of the
workspace may result in damage to expensive equipment. On the other hand, the
use of a fully teleoperated mobile manipulator may require a significant amount
of operator time. In this paper, a semi-autonomous mobile manipulator is
developed for safely and efficiently carrying out machine tending tasks under
human supervision. The robot is capable of generating motion plans from the
high-level task description and presenting simulation results to the human for
approval. The human operator can authorize the robot to execute the
automatically generated plan or provide additional input to the planner to
refine the plan. If the level of uncertainty in some parts of the workspace
model is high, then the human can decide to perform teleoperation to safely
execute the task. Our preliminary user trials show that non-expert operators
can quickly learn to use the system and perform machine tending tasks.
