  This paper improves safe motion primitives-based teleoperation of a
multirotor by developing a hierarchical collision avoidance method that
modulates maximum speed based on environment complexity and perceptual
constraints. Safe speed modulation is challenging in environments that exhibit
varying clutter. Existing methods fix maximum speed and map resolution, which
prevents vehicles from accessing tight spaces and places the cognitive load for
changing speed on the operator. We address these gaps by proposing a high-rate
(10 Hz) teleoperation approach that modulates the maximum vehicle speed through
hierarchical collision checking. The hierarchical collision checker
simultaneously adapts the local map's voxel size and maximum vehicle speed to
ensure motion planning safety. The proposed methodology is evaluated in
simulation and real-world experiments and compared to a non-adaptive motion
primitives-based teleoperation approach. The results demonstrate the advantages
of the proposed teleoperation approach both in time taken and the ability to
complete the task without requiring the user to specify a maximum vehicle
speed.
