MOVING OBJECT DETECTING DEVICE AND MOBILE ROBOT

• US 20090052740A1
• Filed: 08/22/2008
• Published: 02/26/2009
• Est. Priority Date: 08/24/2007
• Status: Active Grant

• Current Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Original Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Inventors: Sonoura, Takafumi
• Granted Patent: US 8,218,816 B2
• Time in Patent Office: Days
• US Class Current: 382/103
• CPC Class Codes: G06V 10/24 Aligning, centring, orientation detection or correction of the image

Abstract

A moving object detecting device measures a congestion degree of a space and utilizes the congestion degree for tracking. In performing the tracking, a direction measured by a laser range sensor is heavily weighted when the congestion degree is low. When the congestion degree is high, a sensor fusion is performed by heavily weighting a direction measured by a image processing on a captured image to obtain a moving object estimating direction, and obtains a distance by the laser range sensor in the moving object estimating direction.

Claims

1. A moving object detecting device comprising:

an image capturing unit that captures an image of a circumference of the device;

a range sensor that scans the circumference of the device and measures a distance from the device to an object;

an image processing unit that performs an image processing on the image captured by the image capturing unit to extract a tracking target, which is a moving object to be tracked, from the image and to estimate a distance and a direction from the device to the tracking target based on the image;

a congestion degree measuring unit that sets a congestion degree measuring region around a moving object estimated point where a moving object is previously detected and measures a congestion degree represented by a ratio C of the number of detection points detected by the range sensor of the number of detection points detected by the range sensor in the congestion degree measuring region to a total number of scanning lines of the range sensor passing through within the congestion degree measuring region; and

a calculation unit that obtains a fusion estimation result by performing a calculation using (a) a first moving object tracking result obtained by an output from the range sensor, (b) a second moving object tracking result obtained by the image processing by the image processing unit, and (c) a fusion ratio W₁ that is represented by the following expression (1) where α

, β

, and n are arbitrary constant.

W₁=α

Cⁿ+β

 

 

(1)

2. The device according to claim 1, wherein the calculation unit obtains a fusion estimating direction by performing a calculation using (a) a first tracking target estimating direction obtained by a first moving object tracking algorithm on an output from the range sensor, (b) a second tracking target estimating direction obtained by a second moving object tracking algorithm in the image processing by the image processing unit, and (c) the fusion ratio W₁, and

wherein the calculation unit obtains a distance measured by the range sensor in the fusion estimating direction as a fusion estimating distance.

3. The device according to claim 1, wherein the first tracking algorithm includes:

setting a moving object detection region around the moving object estimated point obtained in a previous detection step; and

setting detection points obtained by the range sensor to be within the moving object detection region as estimating position candidate points representing a position of the moving object in a current detection step.

4. The device according to claim 3, wherein the first tracking algorithm includes:

setting a region obtained by expanding the moving object detection region by a given distance L outward in a normal direction as the congestion degree measuring region; and

measuring the congestion degree utilizing remaining scanning lines other than scanning lines that are detecting any of the estimating position candidate points having a presence probability exceeding a given threshold value δ

, which satisfies 0≦

δ

≦

1, the threshold value δ

being determined in accordance with the position, from among the estimating position candidate points that are within the congestion degree measuring region.

5. The device according to claim 3, wherein, for a case where no estimating position candidate points are detected within the moving object detection region, the first tracking algorithm includes:

setting a prediction position where the moving object is predicted from the previous moving object estimated point as a provisional current estimation position of the tracking target;

adding a lost counter for recording non-detection of the estimating position candidate points; and

continuously performing the tracking of the target object.

6. The device according to claim 5, wherein the first tracking algorithm includes stopping a follow-up operation and transitioning to other operation mode when determined that the tracking target is lost in a case where no estimating position candidate points are detected within the moving object detection region.

7. A mobile robot comprising:

the moving object detecting device according to claim 1;

a drive unit that drives the robot to move on a floor; and

a controller that controls the drive unit to move the robot to follow the tracking target by referring to a tracking target estimating position that is obtained as the fusion estimation result by the calculation unit of the moving object detecting device,

wherein the calculation unit dynamically changes a follow-up gain G for tracking the tracking target to satisfy the following equation (2), where R(0<

R<

1) represents a reflection intensity of a scanning beam of the range sensor, and a second fusion ratio W₂ satisfies the following equation (3), where α

₂, β

₂, and n₂ are arbitrary constant.

G∝

W₁W₂ 

 

(2)

W₂=α

₂Rⁿ²+β

₂ 

 

(3)