Fast continuous regulation of nonholonomic mobile robots

Patent metadata

Field	Value
Publication number	US-12099371-B2
Application number	US-202117338874-A
Country	US
Kind code	B2
Filing date	Jun 4, 2021
Priority date	Jun 4, 2021
Publication date	Sep 24, 2024
Grant date	Sep 24, 2024

Abstract

Embodiments of the disclosure provide methods and systems for continuous regulation of a nonholonomic mobile robot. An exemplary method may include identifying a current pose of the nonholonomic mobile robot in a world frame, where the current pose is represented by a first set of values defining a first set of states of the nonholonomic mobile robot in the world frame; receiving a final goal pose of the nonholonomic mobile robot, where the final goal pose is represented by a second set of values defining a second set of states of nonholonomic mobile robot in the world frame; determining a moving path for moving the nonholonomic mobile robot from the current pose to the final goal pose; and controlling the nonholonomic mobile robot to move from the current pose to the final goal pose according to the moving path, where the nonholonomic mobile robot moves to the final goal pose by converging the nonholonomic mobile robot from the first set of states to the second set of states simultaneously.

First claim

What is claimed is:

1. A method for continuous regulation of a nonholonomic mobile robot, comprising:
identifying a current pose of the nonholonomic mobile robot in a world frame, wherein the current pose is represented by a first set of values defining a first set of states of the nonholonomic mobile robot in the world frame;
receiving a final goal pose of the nonholonomic mobile robot, wherein the final goal pose is represented by a second set of values defining a second set of states of nonholonomic mobile robot in the world frame;
determining a pair of arc-shaped sectors based on a predefined radius and angle in relation to the current pose of the nonholonomic mobile robot;
determining a moving path for moving the nonholonomic mobile robot from the current pose to the final goal pose based on a location of the final goal pose in one of the pair of arc-shaped sectors identified in relation to the current pose and based on a comparison of an orientation error associated with the current pose and the final goal pose with a predefined threshold; and
controlling the nonholonomic mobile robot to move from the current pose to the final goal pose according to the moving path, wherein the nonholonomic mobile robot moves to the final goal pose by converging the nonholonomic mobile robot from the first set of states to the second set of states simultaneously.

2. The method of claim 1 , wherein each of the first and second set of states in the world frame comprises translations on x- and y-axes and an orientation of the nonholonomic mobile robot.

3. The method of claim 1 , wherein determining the moving path for moving the nonholonomic mobile robot from the current pose to the final goal pose based on the location of the final goal pose in one of the pair of arc-shaped sectors identified in relation to the current pose and based on the comparison of the orientation error associated with the current pose and the final goal pose with the predefined threshold comprises:
determining whether a transition goal pose is needed for the nonholonomic mobile robot to move to the final goal pose based on the location of the final goal pose identified in relation to the current pose and the comparison of the orientation error associated with the current pose and the final goal pose with the predefined threshold.

4. The method of claim 3 , wherein determining whether a transition goal pose is needed for the nonholonomic mobile robot to move to the final goal pose based on the location of the final goal pose in one of the pair of arc-shaped sectors identified in relation to the current pose and based on the comparison of the orientation error associated with the current pose and the final goal pose with the predefined threshold comprises:
determining whether the orientation error associated with the current pose and the final pose is less than the predefined threshold;
determining whether the final goal pose is located in an arc-shaped sector on a lateral side of the nonholonomic mobile robot at the current pose, wherein the arc-shaped sector has a predefined angle and radius; and
if the orientation error is less than the predefined threshold and the final goal pose is located in the arc-shaped sector, determining that a transition goal pose is needed for the nonholonomic mobile robot to move to the final goal pose.

5. The method of claim 3 , further comprising:
in response to that the transition goal pose is needed, controlling the nonholonomic mobile robot to move from the current pose to the transition goal pose before moving to the final goal pose.

6. The method of claim 3 , further comprising:
in response to that the transition goal pose is not needed, controlling the nonholonomic mobile robot to move from the current pose directly to the final goal pose.

7. The method of claim 1 , wherein determining the moving path for moving the nonholonomic mobile robot from the current pose to the final goal pose further comprises:
determining whether the nonholonomic mobile robot needs to move backward to the final goal pose; and
if it is determined that the nonholonomic mobile robot needs to move backward to the final goal pose, controlling the nonholonomic mobile robot to move backward to the final goal pose.

8. The method of claim 7 , wherein:
the determining the pair of arc-shaped sectors comprises:
determining an arc-shaped backside sector located on a backside of the current pose; and
determining an arc-shaped front sector located on a front of the final goal pose, and

the determining whether the nonholonomic mobile robot needs to move backward to the final goal pose comprises:
if the nonholonomic mobile robot at the current pose is located in the arc-shaped front sector and the nonholonomic mobile robot at the final goal pose is located in the arc-shaped backside sector, determining that the nonholonomic mobile robot needs to move backward to the final goal pose.

9. The method of claim 1 , wherein controlling the nonholonomic mobile robot to move from the current pose to the final goal pose comprises:
controlling the nonholonomic mobile robot to move from the current pose to a pose within a predetermined proximity to the final goal pose with a predefined toleration on translations; and
controlling the nonholonomic mobile robot to rotate to reduce the orientation error to be smaller than the predefined threshold.

10. The method of claim 1 , wherein the current pose of the nonholonomic mobile robot in the world frame is determined by using a wheel odometry combined with a Light Detection and Ranging (LIDAR)-based Simultaneous Localization and Mapping (SLAM) process.

11. The method of claim 1 , wherein the nonholonomic mobile robot is underactuated with a number of inputs smaller than a degree of freedom.

12. A system for continuous regulation of a nonholonomic mobile robot, comprising:
at least a processor;
a memory coupled to the at least one processor, the memory storing programs that, when executed, cause the at least one processor to:
identify a current pose of the nonholonomic mobile robot in a world frame, wherein the current pose is represented by a first set of values defining a first set of states of the nonholonomic mobile robot in the world frame;
receive a final goal pose of the nonholonomic mobile robot, wherein the final goal pose is represented by a second set of values defining a second set of states of nonholonomic mobile robot in the world frame;
determine a pair of arc-shaped sectors based on a predefined radius and angle in relation to the current pose of the nonholonomic mobile robot;
determine a moving path for moving the nonholonomic mobile robot from the current pose to the final goal pose based on a location of the final goal pose in one of the pair of arc-shaped sectors identified in relation to the current pose and based on a comparison of an orientation error associated with the current pose and the final goal pose with a predefined threshold; and
control the nonholonomic mobile robot to move from the current pose to the final goal pose according to the moving path, wherein the nonholonomic mobile robot moves to the final goal pose by converging the nonholonomic mobile robot to the second set of states simultaneously.

13. The system of claim 12 , wherein each of the first and second set of states in the world frame comprises translations on x- and y-axes and an orientation of the nonholonomic mobile robot.

14. The system of claim 12 , wherein, to determine the moving path for moving the nonholonomic mobile robot from the current pose to the final goal pose based on the location of the final goal pose

Assignees

• Ubtech North America Res And Development Center Corp
• Ubtech Robotics Corp Ltd
• Ubkang Qingdao Tech Co Ltd

Inventors

• Guo Dejun
• Tan Huan

Classifications

• G05D1/43

  Control of position or course in two dimensions [2D] · CPC title

• G05D1/646

  Following a predefined trajectory, e.g. a line marked on the floor or a flight path · CPC title

• G05D1/49

  Control of attitude, i.e. control of roll, pitch or yaw · CPC title

• G05D1/227

  Handing over between remote control and on-board control; Handing over between remote control arrangements · CPC title

• G01S17/89

  for mapping or imaging · CPC title