Wheeled robot and control method thereof

A method for controlling a robot comprising a body, a pair of wheels rotatably provided at a lower part of the body, and a cargo box provided at an upper part of the body, the method comprising:

• controlling a pair of wheel motors and a cargo box motor to allow the robot to make a double axis inverted pendulum motion on an axis of each of the pair of wheels and the cargo box, based on an output from each of an inertial measurement sensor, a pair of wheel encoders and a cargo box encoder, the pair of wheel motors configured to transmit a torque to each of the pair of wheels, the cargo box motor configured to transmit a torque to the cargo box, the inertial measurement sensor configured to measure a tilt angle of the body, the pair of wheel encoders configured to measure a rotational angle of each of the pair of wheels, and the cargo box encoder configured to measure a tilt angle of the cargo box;
• determining, based on the robot being balanced by the double axis inverted pendulum motion, a slope of a current position based on the torque applied to the cargo box, the torque applied to the pair of wheels, and the tilt angle of the body;
• and
• determining a ratio between the tilt angle of the body and the tilt angle of the cargo box based on the slope to thereby move the robot while maintaining balance.