  This paper proposes a robot assembly planning method by automatically reading
the graphical instruction manuals design for humans. Essentially, the method
generates an Assembly Task Sequence Graph (ATSG) by recognizing a graphical
instruction manual. An ATSG is a graph describing the assembly task procedure
by detecting types of parts included in the instruction images, completing the
missing information automatically, and correcting the detection errors
automatically. To build an ATSG, the proposed method first extracts the
information of the parts contained in each image of the graphical instruction
manual. Then, by using the extracted part information, it estimates the proper
work motions and tools for the assembly task. After that, the method builds an
ATSG by considering the relationship between the previous and following images,
which makes it possible to estimate the undetected parts caused by occlusion
using the information of the entire image series. Finally, by collating the
total number of each part with the generated ATSG, the excess or deficiency of
parts are investigated, and task procedures are removed or added according to
those parts. In the experiment section, we build an ATSG using the proposed
method to a graphical instruction manual for a chair and demonstrate the action
sequences found in the ATSG can be performed by a dual-arm robot execution. The
results show the proposed method is effective and simplifies robot teaching in
automatic assembly.
