Picking system including server for assigning task and robot for performing delivery according to assigned task

A task performance method of a system configured to perform a task on a delivery object using a plurality of robots assisting a worker, the task including information on a location where one or more delivery objects are stored, the system including a server and the plurality of robots, the task performance method comprising:

• assigning, by the server, at least one task of a plurality of tasks stored in advance to a first robot among the plurality of robots;
• determining, by the server, a path for arranging the first robot to a first location in which at least one delivery object related to the task assigned to the first robot is stored;
• guiding, by the server, the first robot to the first location according to a determined path;
• guiding, by the server, the first robot arranged in a first position to a second position;
• moving the first robot to a second location when weight of a delivery object loaded on the first robot exceeds a reference weight or a load equal to or larger than a reference value is applied to a predetermined area by the delivery object loaded on the first robot;
• and
• if a loading operation at the first location where at least one shipment related to a first task assigned to the first robot is stored is not completed and the second location is selected based on a user input entered through the first robot, assigning, by the server, the first task that was interrupted at the first location to a second robot corresponding to at least one of a robot closest to the first location, a robot that can first move to the first location after completing an ongoing task, and a robot that most recently performed shipment unloading at a station where shipments are unloaded.