Mothership drone uses sensors to launch and catch child UAV safely
Multimodal Sensor-Gated Mid-Air Launch and Vision-Based Recovery of a Child UAV on a Hovering Mothership Drone
Robotics
Summary
Launching a small drone (child UAV) from a hovering bigger drone (mothership) and catching it in mid-air is tricky. The authors show how combining different sensors like LiDAR, GPS positioning, and the carrier’s motor thrust helps confirm that the child drone is safely docked before the mothership moves. Vision cameras guide the approach, but close to landing, non-visual sensors make sure the child drone is securely sitting. Tests in outdoor flights and simulations showed this method works well to coordinate launch and recovery.
What this means in practice
- •For drone system engineers: Enable reliable mid-air UAV launch and recovery using combined nonvisual sensing and vision-based guidance.
- •For autonomous vehicle developers: Improve autonomous multi-vehicle coordination by integrating range and motor feedback for close-proximity docking operations.
Authors
Aashish Sahu, R. Prasanth Kumar
Abstract
Launching a micro unmanned aerial vehicle (UAV) from a hovering carrier and recovering it in flight requires reliable confirmation that the child is securely seated before the carrier is allowed to descend. This is challenging because vision provides relative guidance but does not directly indicate load transfer, and a downward-facing camera can lose its fiducial near touchdown. This letter presents a mothership-child quadrotor system in which mission transitions are gated by complementary nonvisual sensing. An upward-facing single-beam LiDAR on the recovery deck provides a binary occupancy state using hysteresis and a debounce interval derived from the child's occluding footprint and crossing speed; real-time kinematic (RTK) positioning conditions the carrier hover; and carrier thrust provides a proprioceptive indication of load transfer. In ten outdoor missions using an F450-class mothership and a Q250-class child with camera-guided recovery, nine completed successfully while RTK-fixed positioning was maintained through release and capture. A complementary MuJoCo study of fully autonomous fiducial-based recovery achieved touchdown 0.077 m from the deck center, while marker detection was lost within the final approximately 0.2 m above the docked configuration. In simulation, carrier thrust changed by -17.0 N at release and +17.3 N at capture, agreeing within 6% with the child's 18.0 N hover thrust. The results support a sensing architecture in which vision guides the approach, while range and proprioceptive information corroborate the final docking decision.