Post on 30-May-2018
8/14/2019 Lecture 9 Navigation Part 2
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Heterogeneous Teams of Modular Robots for Mapping and
Exploration (Grabowski et al.)
A team of Millibots (centimeter-scale robots) collaborate to map and explore
unknown environments
To provide two-way communications within the group, each Millibot is equipped
with a radio frequency transmitter and receiver. These units can exchange data at4800 bps at a distance of up to 100 meters (size and power consideration).
Three sensor modules: short-range sonars (0-0.5m), long-range sonars (0.15-1.8m),
and infrared proximity (0-0.25m).
8/14/2019 Lecture 9 Navigation Part 2
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Heterogeneous Teams of Modular Robots for Mapping and
Exploration (Grabowski et al.)
Collaboration
To overcome their individual limitations and accomplish important tasks
ranging from localization to surveillance, mapping, and exploration Self-localization is critical for the success of collaboration
o dead-reckoning, vision-based localization, GPS, landmarks, or map-based
positioning?
o Millibot localization is based on the trilateration: determine the position based ondistance measurements to
known landmarks or beacons
Collaborative localization
o Localization module
Use ultrasound and radio pulses
to measure the distance between
itself and other robot
8/14/2019 Lecture 9 Navigation Part 2
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Heterogeneous Teams of Modular Robots for Mapping and
Exploration (Grabowski et al.)
Mapping and exploration
A group of Millibots can be equipped with similar sensors to cover more
area in less time than a single robotDuring operation, each robot collects information locally about is
surroundings
This data is transmitted to the team leader where it is used to build a
local map centric to that robot
The team leader (or human operator) can utilize the robots lcoal map
information to direct the Millibot around obstacles, investigate
anomalies or generate new pathsIn an unknown environment, robots move to collect new information
about the environment and build composite maps. In turn, the maps
provide clues about the most viable areas of exploration that will furtherincrease the knowledge about the environment
8/14/2019 Lecture 9 Navigation Part 2
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Heterogeneous Teams of Modular Robots for Mapping and
Exploration (Grabowski et al.)
Mapping and exploration
Keep line-of-sight to maintain positions
The team leader can merge the informationfrom several local maps into a single global
map using an occupancy grid with a
Bayesian update rule
This method allows the combination ofsensor readings from different robots and
different time instances.
Zero corresponds to a free cell and one isoccupied. Initially, all cells are 0.5.