Wheeled robot and control method thereof

Patent metadata

Field	Value
Publication number	US-12422855-B2
Application number	US-202318320966-A
Country	US
Kind code	B2
Filing date	May 20, 2023
Priority date	Oct 17, 2022
Publication date	Sep 23, 2025
Grant date	Sep 23, 2025

Abstract

A robot includes a body, a pair of wheels rotatably provided at a lower part of the body, a cargo box provided at an upper part of the body, an inertial measurement sensor configured to measure a tilt angle of the body, a pair of wheel encoders configured to measure a rotational angle of each of the pair of wheels, a cargo box encoder configured to measure a tilt angle of the cargo box, a pair of wheel motors configured to transmit a torque to each of the pair of wheels, a cargo box motor configured to transmit a torque to the cargo box, and a controller. The controller is configured to control the pair of wheel motors and the 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.

First claim

What is claimed is:

1. A robot, comprising:
a body;
a pair of wheels rotatably provided at a lower part of the body;
a cargo box provided at an upper part of the body;
an inertial measurement sensor configured to measure a tilt angle of the body;
a pair of wheel encoders configured to measure a rotational angle of each of the pair of wheels;
a cargo box encoder configured to measure a tilt angle of the cargo box;
a pair of wheel motors configured to transmit a torque to each of the pair of wheels;
a cargo box motor configured to transmit a torque to the cargo box; and
a controller configured to:
control the pair of wheel motors and the 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 the inertial measurement sensor, the pair of wheel encoders, and the cargo box encoder,
determine, based on the robot being balanced by the double axis inverted pendulum motion, a slope of a current position of the robot 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
determine 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.

2. The robot of claim 1 , wherein the controller is configured to estimate the slope using (i) the output of each from the inertial measurement sensor, the pair of wheel encoders, and the cargo box encoder, as state variables and (ii) the torque applied to the cargo box and the torque applied to the pair of wheels, as control input.

3. The robot of claim 2 , wherein the controller is configured to estimate the slope based on (i) a correlation among the state variables and the control input, (ii) a mass and a dimension of each of the body, the pair of wheels, and the cargo box, and (iii) a gravitational acceleration.

4. The robot of claim 2 , wherein the controller is configured to determine a target tilt angle of the body and a target tilt angle of the cargo box to move the robot while maintaining balance in the slope, based on the ratio between the tilt angle of the body and the tilt angle of the cargo box.

5. The robot of claim 4 , wherein the controller is configured to determine the ratio between the tilt angle of the body and the tilt angle of the cargo box in the slope based on the tilt angle of the body, the tilt angle of the cargo box, and an angular speed of the pair of wheels being constant.

6. The robot of claim 5 , wherein the controller is configured to determine the ratio between the tilt angle of the body and the tilt angle of the cargo box based on a slope determined in real time while the robot is moving, to thereby adaptively change the target tilt angle of the cargo box.

7. The robot of claim 5 , wherein the controller is configured to:
determine the target tilt angle of the cargo box to ensure the cargo box is parallel to a ground, and
determine the target tilt angle of the body based on a ratio among the determined target tilt angle of the cargo box, the tilt angle of the body, and the tilt angle of the cargo box.

8. The robot of claim 4 , wherein the controller is configured to perform feedback-control on the pair of wheel motors and the cargo box motor, based on an angular speed of the pair of wheels, the target tilt angle of the body, and the target tilt angle of the cargo box according to a movement command.

9. The robot of claim 1 , wherein the controller is configured to determine a slope in each of the pair of wheels, and determine an average of the slope in each of the pair of wheels as the slope of the current position.

10. The robot of claim 9 , wherein the controller is configured to adjust an output of each of the pair of wheel motors based on the slope in each of the pair of wheels.

11. 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.

12. The method of claim 11 , wherein determining the slope comprises estimating the slope using (i) the output from each of the inertial measurement sensor, the pair of wheel encoders, and the cargo box encoder, as state variables and (ii) using the torque applied to the cargo box and the torque applied to the pair of wheels, as control input.

13. The method of claim 12 , wherein determining the slope comprises estimating the slope based on (i) a correlation among the state variables and the control input, (ii) a mass and a dimension of each of the body, the pair of wheels and the cargo box, and (iii) a gravitational acceleration.

14. The method of claim 12 , further comprising:
determining a target tilt angle of the body and a target tilt angle of the cargo box to move the robot while maintaining balance in the slope, based on the ratio between the tilt angle of the body and the tilt angle of the cargo box.

15. The method of claim 14 , wherein determining the ratio between the tilt angle of the body and the tilt angle of the cargo box to determine the ratio between the tilt angle of the body and the tilt angle of the cargo box in the slope based on the tilt angle of the body, the tilt angle of the cargo box, and an angular speed of the pair of wheels being constant.

16. The method of claim 15 , wherein determining the ratio between the tilt angle of the body and the tilt angle of the cargo box comprises determining the ratio between the tilt angle of the body and the tilt angle of the cargo box based on a slope determined in real time while the robot is moving, to thereby adaptively change the target tilt angle of the cargo box.

17. The method of claim 15 , wherein determining the ratio between the tilt angle of the body and the tilt angle of the cargo box comprises:
determining the target tilt angle of the cargo box to ensure the cargo box is parallel to a ground, and
determining the target tilt angle of the body based on a ratio among the determined target tilt angle of the cargo box, the tilt angle of the body, and the tilt angle of the cargo box.

18. The method of claim 14 , further comprising:
performing feedback-control on the pair of wheel motors and the cargo box motor, based on an angular speed of the pair of wheels, the target tilt angle of the body, and the target tilt angle of the cargo box according to a movement command

Assignees

• Hyundai Motor Co Ltd
• Kia Corp
• Mobinn Inc
• Hyundai Motor Company And
• Kia Corp And

Inventors

• Chung Hoon
• Choi Jin
• Jo Sun Myoung

Classifications

• B62D57/028

  having wheels and mechanical legs (B62D57/024 takes precedence; ground-engaging vehicle fittings for supporting, lifting or manoeuvring the vehicle, wholly or in part B60S9/00) · CPC title

• B62D57/024 Primary

  specially adapted for moving on inclined or vertical surfaces (endless-track vehicles for ascending or descending stairs B62D55/075; hand-carts with provision for travelling up or down stairs B62B5/02) · CPC title

• B60Y2200/48

  Stair-climbing vehicles · CPC title

• B60K7/0007

  the motor being electric · CPC title

• B25J19/02

  Sensing devices · CPC title