3-D relative positioning sensor for indoor flying robots

Abstract

Swarms of indoor flying robots are promising for many applications, including searching tasks in collapsing buildings, or mobile surveillance and monitoring tasks in complex man-made structures. For tasks that employ several flying robots, spatial-coordination between robots is essential for achieving collective operation. However, there is a lack of on-board sensors capable of sensing the highlydynamic 3-D trajectories required for spatial-coordination of small indoor flying robots. Existing sensing methods typically utilise complex SLAM based approaches, or absolute positioning obtained from off-board tracking sensors, which is not practical for real-world operation. This paper presents an adaptable, embedded infrared based 3-D relative positioning sensor that also operates as a proximity sensor, which is designed to enable inter-robot spatial-coordination and goal-directed flight. This practical approach is robust to varying indoor environmental illumination conditions and is computationally simple.Keywords Relative positioning sensing · Indoor flying robots · Collective operation · 3D sensor · Spatial-coordination · Proximity sensing J.F.R. developed the concept of relative positioning sensing for enabling goal-directed flight on indoor collective flying robots, wrote the manuscript, developed the sensor hardware/firmware, developed the calibration tools and characterised the sensor. T.S. extensively contributed to the sensor firmware and characterisation. J.-C.Z. and D.F. conceived and directed the project sponsoring the work described in the article. They also provided continue support and feedback towards reaching the attained results.

Science, technology and the future of small autonomous drones

“…However, perceiving the position of other flying drones is still very challenging. Infrared-based bidirectional communication has been used for detecting the range and bearing of neighbouring drones in indoor environments 78 , but the relatively short range of a few metres prevents its use in outdoor environments. Consequently, recent demonstrations of outdoor flocking of ten fixed-wing drones 79 and ten hovering drones 80 relied on radio communication of GPS coordinates between neighbouring drones.…”

Indoor navigation with a swarm of flying robots

“…This also demonstrates the 3-D capabilities, allowing operation in environments where approaches that assume 2-D flight might fail [11]. Although the relative positioning sensor is robust to varied illumination (up to 10, 000 lux, [25]), the sensor is affected by reflections that can lead to interference when close to reflective surfaces, which is exploited for the proximity sensing. It may be possible to mitigate the interference by analysing the sensor's self-reflection.…”

“…To achieve autonomous flight a novel methodology is proposed using a new 3-D relative positioning sensor [25]. The beacons act as static references allowing flying explorers to estimate their egomotion.…”

“…However, the utilised relative positioning sensor suffers from unreliable measurements when one robot is directly below another [25]. Therefore, explorers select the closest beacon in the opposite direction of the flight.…”

“…Alternative methods using dry-adhesives or mechanical gripping are viable [28], or the robots could land on the ground. This work uses a 3-D relative positioning sensor specially designed for flying robots [25], [29]. The proximity sensing of the relative positioning system was used to sense the local environment.…”