Prof. Dr. Patrick Baudisch

FoolProofJoint: Reducing Assembly Errors of Laser Cut 3D Models by Means of Custom Joint Patterns

We present FoolProofJoint, a software tool that simplifies the assembly of laser-cut 3D models and reduces the risk of erroneous assembly. FoolProofJoint achieves this by modifying finger joint patterns. Wherever possible, FoolProofJoint makes similar looking pieces fully interchangeable, thereby speeding up the user’s visual search for a matching piece. When that is not possible, FoolProofJoint gives finger joints a unique pattern of individual finger placements so as to fit only with the correct piece, thereby preventing erroneous assembly. In our benchmark set of 217 laser-cut 3D models downloaded from kyub.com, FoolProofJoint made groups of similar looking pieces fully interchangeable for 65% of all groups of similar pieces; FoolProofJoint fully prevented assembly mistakes for 97% of all models.

In order to eliminate assembly errors, FoolProofJoint optimizes finger joint patterns, so as to (a) make pieces interchangeable by giving them the same joint patterns where pieces have an identical shape, (b) prevent symmetric pieces from being mounted in the wrong orientation, and (c) prevent incorrect pieces from being assembled.

In the first step of the algorithm, FoolProofJoint creates joints in a way that maximizes interchangeability and symmetricity in the model. The key to maximizing these objectives lies in how the material in the corners of the model is assigned to different plates. The corner assignment itself consists of two steps. First, FoolProofJoint assigns priorities for the pieces intersecting at each corner. Second, it decides whether pieces should or should not fill corners to achieve interchangeability and symmetricity.

In the second step of the algorithm, FoolProofJoint prevents assembly errors by making joint patterns distinct when necessary. FoolProofJoint differentiates joint patterns by shifting fingers. After changing a joint pattern, FoolProofJoint also updates identical and corresponding joint patterns to maintain interchangeability and symmetricity.