State estimation for legged robot

A state estimation apparatus for controlling a motor of a legged robot, the state estimation apparatus comprising:

• processing circuitry configured to:
• receive first sensor information from a first sensor of the legged robot at a first observation frequency and second sensor information from a second sensor of the legged robot at a second observation frequency;
• determine, via a first Kalman filter, first state information of the legged robot for a period of time based on the first sensor information and the second sensor information, the first state information indicating first position information of a body of the legged robot, first velocity information of the body of the legged robot, and leg position information of legs of the legged robot in a world coordinate system;
• receive third sensor information from a third sensor of the legged robot at a third observation frequency that is less than the first observation frequency and the second observation frequency, the third sensor information indicating second position information of the body of the legged robot and second velocity information of the body of the legged robot in the world coordinate system;
• determine, via a second Kalman filter, second state information of the legged robot based on the third sensor information and the first state information for the period of time;
• and
• determine a position of the legged robot and a velocity of the legged robot at a current time through an update of a subset of the update-first state information of the legged robot corresponding to the current time based on the second state information of the legged robot,
• wherein the motor of the legged robot is controlled based on the position of the legged robot and the velocity of the legged robot at the current time.

A non-transitory computer-readable storage medium storing instructions which, when executed by a processor, cause the processor to perform a state estimation method for controlling a motor of a legged robot, the method comprising:

• receiving first sensor information from a first sensor of the legged robot at a first observation frequency and second sensor information from a second sensor of the legged robot at a second observation frequency;
• determining, via a first Kalman filter, first state information of the legged robot for a period of time based on the first sensor information and the second sensor information, the first state information indicating first position information of a body of the legged robot, first velocity information of the body of the legged robot, and leg position information of legs of the legged robot in a world coordinate system;
• receiving third sensor information from a third sensor of the legged robot at a third observation frequency that is less than the first observation frequency and the second observation frequency, the third sensor information indicating second position information of the body of the legged robot and second velocity information of the body of the legged robot in the world coordinate system;
• determining, via a second Kalman filter, second state information of the legged robot based on the third sensor information and the first state information for the period of time;
• and
• determining a position of the legged robot and a velocity of the legged robot at a current time through updating a subset of the first state information of the legged robot corresponding to the current time based on the second state information of the legged robot,
• wherein the motor of the legged robot is controlled based on the position of the legged robot and the velocity of the legged robot at the current time.