A robot dialogue system includes a robot with a processor and memory that communicates with a user and a dialogue server with a processor and memory that controls the robot. From a user inquiry the robot calculates speech content and a confidence factor and transmits the speech content and the confidence factor to the dialogue server, which stores an action and a confidence factor corresponding to the speech content in state information. The dialogue server selects a new action having the highest confidence factor in the state information, calculates a cost incurred when the new action is implemented from the robot's present state, selects a combination of candidates excluding the highest confidence factor action as a new candidate of action, calculates a cost incurred when the new candidate of action is implemented, and selects an action or a candidate of action with the lowest cost as a new action.
ROBOT DIALOGUE SYSTEM AND CONTROL METHOD OF ROBOT DIALOGUE SYSTEM