Flying a swarm of micro drones in a forest without crashing can be quite a challenge. Xin Zhou and his colleges at Zhejiang University in China have come with miniature fully autonomous drones with a trajectory planner that can navigate in a forest with limited information from their onboard sensors.
These drones weigh 300 grams and are made with off-the-shelf computer components. They are equipped with RGB cameras. The planner addresses “flight efficiency, obstacle avoidance, and inter-robot collision avoidance, dynamical feasibility, and swarm coordination”. More information is available here.