Robotic additive construction of bar structures: Unified sequence and motion planning

TL;DR

This paper introduces a unified automated planning method for sequencing and motion planning in robotic additive construction of bar structures, enhancing efficiency, safety, and design flexibility.

Contribution

It presents a generalized approach that simultaneously plans construction sequences and robot motions, applicable to various additive manufacturing processes like extrusion and bar assembly.

Findings

Successfully applied to simulated and real-world tasks

Enabled planning for complex double tangent bar system

Demonstrated effectiveness on a human-scale prototype

Abstract

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.