The application of robotics to the assembly of flexible parts by sewing.

This thesis concerns the development of a robotic cell to
perform assembly and handling operations on cloth.- A
flexible automation approach was adopted, in which the
robot was required to control the cloth panel during both
handling and sewing operations, without the aid of hard
automation attachments which might limit the flexibility of
the system. The cell consisted of an adaptively controlled
robot, a hierarchy of controllers, a conventional sewing
machine, a two-fingered fabric steering end-effector, and
several sensor systems.
A technique was developed for producing a seam parallel to
an edge of arbitrary contour, in which two cameras, a
cloth tension sensor and the sewing machine's shaft encoder
provided the sensory input. Two sensory servo control
systems were required, one control system generated the
robot's trajectory to maintain a small constant cloth
tension, and the other directed the robot to manipulate the
cloth panel to maintain a constant seam width.
The design of the cloth tension control was based on the
measured frequency response of the open loop system. The
seam width control was designed using simulation studies,
which accounted for the control transfer function, and nonlinearities
such as camera pixel resolution, time delays
and robot motion limitations.
Several robotic handling techniques were developed, so that
a cloth panel placed arbitrarily on the sewing table could
be set up for an edge seaming operation, and the cloth
could be rotated about the needle. The system's flexibility
was demonstrated in the assembly of an irregularly shaped
cloth panel, in which three adjacent sides were sewn up.