Decentralized Collective Construction Techniques for Large
Scale Structures
in Unstructured Environments
Work in Progress
Large scale construction projects in extraterrestrial environments require a team of construction robots that can autonomously and cooperatively operate in unstructured terrains. In this work, we investigate techniques required to design a decentralized coordination algorithm for a multi-robot construction system that is tasked to build a large rectilinear structure many times the size of an individual robot.
Let's say, in an unstructured environment, we want to build a barrier target structure as shown
here. This structure can be decomposed into a robot deposition path where the center of this
path can then be represented as a simple 1D height map.
The intersection of markers on the path and the different levels of the target structure
represent the various goals a robot needs to reach by depositing material along its path thereby
constructing navigable substructures.
We can begin the construction process with 3 robots, each starting at a specific entry point to
the structure. The robots deposit material (shown in red) in order to reach their various
navigation goals and also keep track of the structure state.
Each robot performs this process independently and the reference map provides a compact way to
record and communicate their progress to other robots. Distribution of tasks takes place as a
result of local interactions and the system may be scaled at any time during the construction
process. Thus, the entire target structure may be constructed in a decentralized manner.
Motivation
Reliable and robust construction in unstructured environments
Structures that are many times the size of an individual agent
Inspiration from nature - construction usually guided by templates and stigmergy
Why Navigable Structures?
Exploration:
Move to locations that were previously inaccessible
Large-scale operations:
Build structures many times the size of an individual agent
Robot System
A newer, modular and self contained robot system that can temporarily store stones for future construction tasks. The picture depicts a robot design concept.
A compliant gripper allows the robot to pick up previously unknown, found stones from a pile.
The compliant gripper fingers taper towards their tips to provide enough pinching force to also pickup small regolith bags. Picking up individual bags from a pile is an involved task. However, multiple bags picked up from a pile may be separated using environmental features. The video demonstrates this idea.