  We present a modular framework for solving a motion planning problem among a
group of robots. The proposed framework utilizes a finite set of low level
motion primitives to generate motions in a gridded workspace. The constraints
on allowable sequences of motion primitives are formalized through a maneuver
automaton. At the high level, a control policy determines which motion
primitive is executed in each box of the gridded workspace. We state general
conditions on motion primitives to obtain provably correct behavior so that a
library of safe-by-design motion primitives can be designed. The overall
framework yields a highly robust design by utilizing feedback strategies at
both the low and high levels. We provide specific designs for motion primitives
and control policies suitable for multi-robot motion planning; the modularity
of our approach enables one to independently customize the designs of each of
these components. Our approach is experimentally validated on a group of
quadrocopters.
