Robot and control system

A robot system, comprising a robot and a low-frequency external module disposed outside the robot,

• the robot comprising:
• a body;
• a plurality of legs extended from the body the robot configured to move by the operation of the plurality of legs;
• and a control module configured to control an actuator being a power source for driving the robot and a high-frequency internal module mounted in the robot,
• wherein
• the external module is configured to search at least one external action candidate, as an external action plan, from a plurality of external action candidates in a second search range on the basis of measured state values of the robot, each of the external action candidates is a combination of unit action behaviors of the robot, each of the unit action behaviors is denoted by one or a plurality of continuous state variable values and one or a plurality of discrete state variable values, the at least one external action candidate has a goodness of fit appropriate for a specified action objective of the external action candidates, the goodness of fit is a fitness for the specified action objective and is defined on the basis of a predicted state of the robot denoted by the continuous state variable values;
• the internal module is configured to search at least one internal action candidate, as an internal action plan, from a plurality of internal action candidates in a first search range on the basis of measured state values of the robot, the first search range is defined smaller than the second search range, each of the internal action candidates is a combination of the unit action behaviors of the robot, the at least one internal action candidate has a goodness of fit appropriate for a specified action objective of the internal action candidates, the goodness of fit is a fitness for the specified action objective and is defined on the basis of the predicted state of the robot denoted by the continuous state variable values;
• the control module is configured to control the actuator according to the internal action plan determined by the internal module;
• and
• each of the internal module and the external module are configured to search a gait of the robot over a specified number of footsteps constituted by a specified combination of various types of the unit action behaviors as the internal action candidate and the external action candidate.