  Additive robotic construction of building-scale discrete bar structures, such
as trusses and space frames, is increasingly attractive due to the potential
improvements in efficiency, safety, and design possibilities. However,
programming complex robots, such as manipulators with seven degrees of freedom,
to successfully complete construction tasks can be tedious, challenging, or
impossible for a human to do manually. Namely, the structure must be
constructed in a sequence that preserves structural properties, such as
stiffness, at each step. At the same time, this sequence must allow for the
robot to precisely manipulate elements within the in-progress structure while
respecting geometric constraints that, for example, ensure the robot does not
collide with what it has built. In this work, we present an automated and newly
generalized planning approach for jointly finding a construction sequence and
robot motion plan for additive construction that satisfies these requirements.
Our approach can be applied in a variety of additive construction processes,
and we demonstrate it specifically on spatial extrusion and discrete bar
assembly in this paper. We demonstrate the effectiveness of our approach on
several simulated and real-world extrusion and assembly tasks, including a
human-scale physical prototype, for which our algorithm is deployed for the
first time to plan the assembly of a complicated double tangent bar system
design.
