US-12625504-B2 - Autonomous mobile device and control method thereof

US12625504B2US 12625504 B2US12625504 B2US 12625504B2US-12625504-B2

Abstract

The present disclosure provides a control method for an autonomous mobile device. The control method includes obtaining a pose of a target point; determining motion control parameters based on the pose of the target point; and controlling, according to the motion control parameters, the autonomous mobile device to move along a motion trajectory. A path curvature of the motion trajectory includes an inverse proportional function of a distance from the autonomous mobile device to the target point. A coefficient of the inverse proportional function includes a term that is functionally related to a lateral offset between the autonomous mobile device and the target point, where the lateral offset is associated with an orientation of the target point.

Inventors

Sheng-Kai Pan
YI-CHENG JIANG
Yu-Jun HUANG

Assignees

FAROBOT INC.

Dates

Publication Date: 20260512
Application Date: 20240213
Priority Date: 20231228

Claims (16)

1 . A control method for an autonomous mobile device, the method comprising: obtaining a pose of a target point comprising: obtaining a plurality of target poses of the target point at a plurality of time points through a sensor system, the plurality of target poses at the plurality of time points comprising a first target pose at a first time point, and the first target pose being detected and obtained by an optical radar on the autonomous mobile device; and calculating a weighted average of the plurality of target poses to obtain a current target pose, a weight corresponding to the first target pose being negatively correlated with a distance between the target point and the autonomous mobile device; determining one or more motion control parameters based on the pose of the target point; and controlling the autonomous mobile device to move along a motion trajectory based on the one or more motion control parameters, wherein a path curvature of the motion trajectory comprises an inverse proportional function of a distance between the autonomous mobile device and the target point, a coefficient of the inverse proportional function comprises a term functionally related to a lateral offset between the autonomous mobile device and the target point, and the lateral offset is associated with an orientation of the target point.
2 . The method of claim 1 , wherein the lateral offset is further associated with a position of the autonomous mobile device.
3 . The method of claim 1 , wherein obtaining of the plurality of target poses of the target point at the plurality of time points through the sensor system comprises: detecting the target point through the sensor system to obtain a sensing result; and transforming the sensing result into an odometry coordinate system to obtain one of the plurality of target poses.
4 . The method of claim 3 , further comprising: detecting a motion of the autonomous mobile device through the sensor system; calculating a current device pose of the autonomous mobile device in the odometry coordinate system based on the motion; and calculating a current relative pose between the target point and the autonomous mobile device based on the current target pose and the current device pose.
5 . The method of claim 1 , wherein the plurality of target poses at the plurality of time points comprises a second target pose at a second time point, the second target pose is detected and obtained by a camera on the autonomous mobile device, and a weight corresponding to the second target pose is negatively correlated with a velocity of the autonomous mobile device at the second time point.
6 . The method of claim 1 , further comprising: determining a pose difference between the autonomous mobile device and the target point; deciding whether to stop the autonomous mobile device based on the pose difference; after stopping the autonomous mobile device, re-obtaining the pose of the target point through the sensor system; and correcting a pose error of the autonomous mobile device based on the re-obtained pose of the target point, wherein the pose error comprises at least one of a lateral error, a longitudinal error, and an angle error.
7 . The method of claim 1 , wherein the one or more motion control parameters comprise a linear velocity and an angular velocity, and determining the one or more motion control parameters based on the pose of the target point comprises: determining the linear velocity; calculating a current curvature based on a current distance between the autonomous mobile device and the target point, a current orientation of the autonomous mobile device, and a current orientation of the target point; and calculating the angular velocity based on the linear velocity and the current curvature.
8 . The method of claim 1 , wherein the autonomous mobile device comprises a Non-Omnidirectional Drive system.
9 . An autonomous mobile device, comprising: a sensor system; a drive system; and a controller coupled to the sensor system and the drive system, and configured to: obtain a pose of the target point comprising: obtaining a plurality of target poses of the target point at a plurality of time points through the sensor system, the plurality of target poses at the plurality of time points comprising a first target pose at a first time point, and the first target pose being detected and obtained by an optical radar on the autonomous mobile device; and calculating a weighted average of the plurality of target poses to obtain a current target pose, a weight corresponding to the first target pose being negatively correlated with a distance between the target point and the autonomous mobile device; determine one or more motion control parameters based on the pose of the target point; and control the autonomous mobile device to move along a motion trajectory based on the one or more motion control parameters, wherein a path curvature of the motion trajectory comprises an inverse proportional function of a distance between the autonomous mobile device and the target point, a coefficient of the inverse proportional function comprises a term functionally related to a lateral offset between the autonomous mobile device and the target point, and the lateral offset is associated with an orientation of the target point.
10 . The autonomous mobile device of claim 9 , wherein the lateral offset is further associated with a position of the autonomous mobile device.
11 . The autonomous mobile device of claim 9 , wherein obtaining of the plurality of target poses of the target point at the plurality of time points through the sensor system comprises: detecting the target point through the sensor system to obtain a sensing result; and transforming the sensing result into an odometry coordinate system to obtain one of the plurality of target poses.
12 . The autonomous mobile device of claim 11 , wherein the controller is further configured to: detect a motion of the autonomous mobile device through the sensor system; calculate a current device pose of the autonomous mobile device in the odometry coordinate system based on the motion; and calculate a current relative pose between the target point and the autonomous mobile device based on the current target pose and the current device pose.
13 . The autonomous mobile device of claim 9 , wherein the plurality of target poses at the plurality of time points comprises a second target pose at a second time point, the second target pose is detected and obtained by a camera on the autonomous mobile device, and a weight corresponding to the second target pose is negatively correlated with a velocity of the autonomous mobile device at the second time point.
14 . The autonomous mobile device of claim 9 , wherein the controller is further configured to: determine a pose difference between the autonomous mobile device and the target point; decide whether to stop the autonomous mobile device based on the pose difference; after stopping the autonomous mobile device, re-obtain the pose of the target point through the sensor system; and correct a pose error of the autonomous mobile device based on the re-obtained pose of the target point, wherein the pose error comprises at least one of a lateral error, a longitudinal error, and an angle error.
15 . The autonomous mobile device of claim 9 , wherein the one or more motion control parameters comprise a linear velocity and an angular velocity, and determining the one or more motion control parameters based on the pose of the target point comprises: determining the linear velocity; calculating a current curvature based on a current distance between the autonomous mobile device and the target point, a current orientation of the autonomous mobile device, and a current orientation of the target point; and calculating the angular velocity based on the linear velocity and the current curvature.
16 . The autonomous mobile device of claim 9 , wherein the drive system comprises a Non-Omnidirectional Drive system.

Description

CROSS-REFERENCE TO RELATED APPLICATION The present application claims the benefit of and priority to China Patent Application No. 202311842073.0, filed on Dec. 28, 2023, the contents of which are hereby fully incorporated herein by reference for all purposes. FIELD The present disclosure generally relates to automatic control technology and, more particularly, to an autonomous mobile device and its control method during docking stages. BACKGROUND Autonomous mobile units play a crucial role in various fields, such as automated manufacturing, robot navigation, precision medical devices, and unmanned transportation systems. However, current autonomous mobile units face numerous unresolved problems in alignment control (e.g., docking control). One of the problems arises from the algorithms. Specifically, the motion control systems of general autonomous mobile units often use more basic path planning algorithms that may not fully consider the environmental and operational requirements during the docking stage. Therefore, when these path planning algorithms are applied to the docking stage, unnecessary adjustments and corrections may be required, thus affecting the smoothness and efficiency of the docking process. Another problem arises from the stability of the sensors. The stability of the sensors is particularly crucial when making subtle adjustments and achieving precise alignment. If the sensor data exhibits significant fluctuations or drift, not only will the drift/fluctuation affects the smoothness and accuracy of the alignment but may also impact the overall reliability and safety of the system. Therefore, there is room for improvement, which includes a method for controlling autonomous mobile units to enable smoother and more precise alignment operations such as docking. SUMMARY In view of the above, the present disclosure provides a control method for an autonomous mobile device that can quickly correct the lateral offset between itself and the target point, thus enhancing the smoothness and efficiency of alignment between the autonomous mobile device and the target point. A first aspect of the present disclosure provides a control method for an autonomous mobile device. The method includes: obtaining a pose of a target point; determining a motion control parameter based on the pose of the target point; and controlling the autonomous mobile device to move along a motion trajectory according to multiple motion control parameters including the motion control parameter. A path curvature of the motion trajectory includes an inverse proportional function of a distance between the autonomous mobile device and the target point. A coefficient of the inverse proportional function includes a term which is functionally related to a lateral offset between the autonomous mobile device and the target point, and the lateral offset is associated with an orientation of the target point. In some implementations of the first aspect, the lateral offset is further associated with a position of the autonomous mobile device. In some implementations of the first aspect, the obtaining of the pose of the target point includes: obtaining multiple target poses of the target point at multiple time points through a sensor system; calculating a weighted average of the multiple target poses to obtain a current target pose; and calculating a current relative pose between the target point and the autonomous mobile device based on the current target pose. In some implementations of the first aspect, the obtaining of the multiple target poses of the target point at multiple time points through a sensor system includes: detecting the target point through the sensor system to obtain a sensing result; and transforming the sensing result into an odometry coordinate system to obtain one of the target poses. In some implementations of the first aspect, the method further includes: detecting a motion of the autonomous mobile device through the sensor system; calculating a current device pose of the autonomous mobile device in the odometry coordinate system based on the motion; and calculating a current relative pose between the target point and the autonomous mobile device based on the current target pose and the current device pose. In some implementations of the first aspect, the multiple target poses at multiple time points include a first target pose at a first time point, the first target pose is detected and obtained by a camera on the autonomous mobile device, and a weight corresponding to the first target pose is negatively correlated with a velocity of the autonomous mobile device at the first time point. In some implementations of the first aspect, the multiple target poses at multiple time points include a first target pose at a first time point, the first target pose is detected and obtained by an optical radar on the autonomous mobile device, and a weight corresponding to the first target pose is negatively correlated with a distanc