  This paper presents an Expert-guided Mixed-Initiative Control Switcher
(EMICS) for remotely operated mobile robots. The EMICS enables switching
between different levels of autonomy during task execution initiated by either
the human operator and/or the EMICS. The EMICS is evaluated in two disaster
response inspired experiments, one with a simulated robot and test arena, and
one with a real robot in a realistic environment.
  Analyses from the two experiments provide evidence that: a) Human-Initiative
(HI) systems outperform systems with single modes of operation, such as pure
teleoperation, in navigation tasks; b) in the context of the simulated robot
experiment, Mixed-Initiative (MI) systems provide improved performance in
navigation tasks, improved operator performance in cognitive demanding
secondary tasks, and improved operator workload compared to HI. Results also
reinforce previous human-robot interaction evidence regarding the importance of
the operator's personality traits and their trust in the autonomous system.
Lastly, our experiment on a physical robot provides empirical evidence that
identify two major challenges for MI control: a) the design of context-aware MI
control systems; and b) the conflict for control between the robot's MI control
system and the operator. Insights regarding these challenges are discussed and
ways to tackle them are proposed.
