14,009 research outputs found
Pressure dependent friction on granular slopes close to avalanche
We investigate the sliding of objects on an inclined granular surface close
to the avalanche threshold. Our experiments show that the stability is driven
by the surface deformations. Heavy objects generate footprint-like deformations
which stabilize the objects on the slopes. Light objects do not disturb the
sandy surfaces and are also stable. For intermediate weights, the deformations
of the surface destabilize the objects and generate sliding. A characteristic
pressure for which the solid friction is minimal is evidenced. Applications to
the locomotion of devices and animals on sandy slopes as a function of their
mass are proposed
Search-based 3D Planning and Trajectory Optimization for Safe Micro Aerial Vehicle Flight Under Sensor Visibility Constraints
Safe navigation of Micro Aerial Vehicles (MAVs) requires not only
obstacle-free flight paths according to a static environment map, but also the
perception of and reaction to previously unknown and dynamic objects. This
implies that the onboard sensors cover the current flight direction. Due to the
limited payload of MAVs, full sensor coverage of the environment has to be
traded off with flight time. Thus, often only a part of the environment is
covered.
We present a combined allocentric complete planning and trajectory
optimization approach taking these sensor visibility constraints into account.
The optimized trajectories yield flight paths within the apex angle of a
Velodyne Puck Lite 3D laser scanner enabling low-level collision avoidance to
perceive obstacles in the flight direction. Furthermore, the optimized
trajectories take the flight dynamics into account and contain the velocities
and accelerations along the path.
We evaluate our approach with a DJI Matrice 600 MAV and in simulation
employing hardware-in-the-loop.Comment: In Proceedings of IEEE International Conference on Robotics and
Automation (ICRA), Montreal, Canada, May 201
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