Falling Into Place: Drop Assembly of Interlocking Puzzles

This paper explores a system for assembling structures by dropping block components into place. During and after assembly, the blocks are held together by geometric interlock, so that fasteners or mortar are only needed to bind the final block to one of its neighbors. Drop assembly is a promising strategy for assembly by swimming or flying robots, as it may allow structures to be built without requiring close contact with the existing structure. The current paper explores a mathematical model of interlock, and presents a particular block design that allows interlock to be achieved using only gravity. Proof-of-concept demonstrations of the system are presented using a low-cost and relatively low-precision robot arm. The paper finally analyzes some of the potential limitations of the approach, particularly including flexing of the structure due to manufacturing tolerance limitations.