#### On Throughput Maximization in Constant Travel-Time
Robotic Cells

**Abstract: **We
consider the problem of scheduling operations in bufferless robotic cells that
produce identical parts. The objective is to find a cyclic sequence of
robot moves that minimizes the long-run average time to produce a part, or
equivalently, maximizes the throughput rate. The robot can be moved in
simple cycles that produce one unit or, in more complicated cycles, that produce
multiple units. Because one-unit cycles are the easiest to understand, implement
and control, they are widely used in industry. We analyze one-unit cycles
for a class of robotic cells called *constant travel-time robotic cells.*
We complete a structural analysis
of the class of one-unit cycles and obtain a polynomial time algorithm for
finding an optimal one-unit cycle.

Constant travel-time robotic cells are used in real manufacturing
operations that the authors have encountered during their interactions with
companies. The results and the analysis in this paper offer practitioners
(i) a tool to experiment with and study the design of a proposed robotic cell
during a prototyping exercise, (ii) a lower bound on the throughput of a
robotic cell to help them make an informed assessment of the ultimate
productivity level and (iii) a benchmark throughput level (for comparison
purposes) for robotic cells whose operations differ slightly from those
discussed in this paper.