A machine learning device for learning a motion of a robot engaged in a task performed by a human and a robot in cooperation with each other, including a state observation unit that observes a state variable indicating a state of the robot when the human and the robot cooperate with each other and perform a task; a reward calculation unit that calculates a reward based on control data and the state variable for controlling the robot and on an action of the human; and a value function update unit that updates an action value function for controlling a motion of the robot, based on the reward and the state variable.
Machine learning device, robot system, and machine learning method for learning motion of robot engaged in task performed by human and robot in cooperate with each other