M3RS: Multi-agent, Multi-objective, and Multi-mode Routing and Scheduling

Abstract:

In this work, we present a novel problem and its solution coined multi-agent, multi-objective, multi-mode routing and scheduling (M3RS). The formulation for M3RS is introduced for time-bound multi-agent, 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. M3RS assigns an optimal sequence of tasks and the execution modes to each agent. The routes and associated modes are dependent on user preferences for different objective criteria. The need for M3RS comes from multi-robot applications in which a trade-off between multiple criteria arises from different task execution modes. We use M3RS 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 M3RS. 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 M3RS 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.


Simulated and Hardware Demonstrations:

In this video, you see five robots working on a disinfection mission. Each target surface must be disinfected in a specified time-window. The M3RS formulation is used to assign disinfection tasks and associated modes to different robots while adhering to user preference and mission constraints of time and capacity. The user preference for this disinfection mission prioritises quantity over quality of disinfection. over quantity. The schedules generated by M3RS choose lower disinfection quality modes in order to maximize the time available to complete as many jobs as possible. This simulation is conducted in Robot Operating System. (Note: no audio, Speed: 5X)

In this video, a mission of disinfection of 6 tables by two robots is demonstrated. The user preference in this case priorities quantity over quality. Hence, the robots disinfect all table although some of the tables  are disinfected at lower quality modes. (Note: no audio, Speed: 5X)


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