  In this paper, we present a novel problem coined multi-robot,
multi-objective, and multi-mode routing and scheduling (M^3RS). The formulation
for M^3RS is introduced for time-bound multi-robot, multi-objective routing and
scheduling missions where each task has multiple execution modes. Different
execution modes have distinct resource consumption, associated execution time,
and quality. M^3RS assigns the optimal sequence of tasks and the execution
modes to each agent. The routes and associated modes depend on user preferences
for different objective criteria. The need for M^3RS comes from multi-robot
applications in which a trade-off between multiple criteria arises from
different task execution modes. We use M^3RS for the application of multi-robot
disinfection in public locations. The objectives considered for disinfection
application are disinfection quality and number of tasks completed. A
mixed-integer linear programming model is proposed for M^3RS. Then, a
time-efficient column generation scheme is presented to tackle the issue of
computation times for larger problem instances. The advantage of using multiple
modes over fixed execution mode is demonstrated using experiments on synthetic
data. The results suggest that M^3RS provides flexibility to the user in terms
of available solutions and performs well in joint performance metrics. The
application of the proposed problem is shown for a team of disinfection
robots.} The videos for the experiments are available on the project website:
https://sites.google.com/view/g-robot/m3rs/ .
