System and method for detecting traveling state

• US 20050278068A1
• Filed: 05/11/2005
• Published: 12/15/2005
• Est. Priority Date: 06/11/2004
• Status: Active Grant

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Hong, Sun-gi, Song, Jeong-gon
• Granted Patent: US 8,014,900 B2
• Time in Patent Office: Days
• US Class Current: 700/259
• CPC Class Codes: G05D 1/0253 extracting relative motion information from a plurality of images taken successively, e.g. visual odometry, optical flow determining position or orientation from images G06T7/70
• CPC Class Codes: G05D 1/0272 comprising means for registering the travel distance, e.g. revolutions of wheels measuring distance traversed on the ground by vehicles, e.g. using odometers G01C22/00
• CPC Class Codes: G06T 7/70 Determining position or orientation of objects or cameras camera calibration G06T7/80

Abstract

A system and method for detecting a traveling state. The system includes an image receiving unit acquiring two consecutive images and detecting first traveling information from image information regarding each of the two consecutive images, a traveling information processing unit connected to a driver moving in a direction perpendicular to a direction in which the images are acquired, the traveling information processing unit detecting second traveling information from information regarding the driver, and a control unit determining the traveling state based on the first traveling information and the second traveling information.

Claims

1. A system for detecting a traveling state, comprising:

an image receiving unit acquiring two consecutive images and detecting first traveling information from image information regarding each of the two consecutive images;

a traveling information processing unit connected to a driver moving in a direction perpendicular to a direction in which the images are acquired, the traveling information processing unit detecting second traveling information from the driver; and

a control unit determining the traveling state based on the first traveling information and the second traveling information.

2. The system of claim 1, wherein the traveling information includes moving distance information.

3. The system of claim 2, wherein the first traveling information includes information indicating a rectilinear movement state using a difference in the image information between the two consecutive images,

the second traveling information includes integrated distance information indicating a distance that the driver moves, and

the control unit determines that the traveling state is abnormal when the first traveling information indicates that a rectilinear movement is not performed and the second traveling information exceeds a predetermined threshold value.

4. The system of claim 3, wherein, when the traveling state is determined to be abnormal, the control unit moves the driver backward to achieve a normal traveling state.

5. The system of claim 3, wherein, when the traveling state is determined to be abnormal, the control unit rotates the driver to achieve a normal traveling state.

6. The system of claim 1, wherein the traveling information includes rotation information.

7. The system of claim 6, wherein the first traveling information includes information on an angle corresponding to a least value among values obtained by respectively converting the two consecutive images into two polar coordinate images having an angle and a distance corresponding to the angle as coordinate axes and by calculating differences in image information between the two polar coordinate images while moving one of the two polar coordinate images in a direction of a coordinate axis indicating the angle,

the second traveling information includes information indicating a rotational displacement of the driver, and

the control unit determines that the traveling state is abnormal when a different between a value of the first traveling information and a value of the second traveling information exceeds a threshold value.

8. The system of claim 7, wherein, when the traveling state is determined to be abnormal, the control unit set the first traveling information as a current rotation angle.

9. A method of detecting a traveling state, comprising:

acquiring two consecutive images and detecting first traveling information from image information regarding each of the two consecutive images;

detecting second traveling information from a driver moving in a direction perpendicular to a direction in which the images are acquired; and

determining the traveling state based on the first traveling information and the second traveling information.

10. The method of claim 9, wherein the traveling information includes moving distance information.

11. The method of claim 10, wherein the first traveling information includes information indicating a rectilinear movement state using a difference in the image information between the two consecutive images,

the second traveling information includes integrated distance information indicating a distance that the driver moves, and

the determining includes indicating that the traveling state is abnormal when the first traveling information indicates that a rectilinear movement is not performed and the second traveling information exceeds a threshold value.

12. The method of claim 11, wherein, when the traveling state is determined to be abnormal, the determining of the traveling state includes moving the driver backward to achieve a normal traveling state.

13. The method of claim 11, wherein, when the traveling state is determined to be abnormal, the determining of the traveling state includes rotating the driver to achieve a normal traveling state.

14. The method of claim 9, wherein the traveling information includes rotation information.

15. The method of claim 14, wherein the detecting of the first traveling information includes converting the acquired two consecutive images into two polar coordinate images having an angle and a distance corresponding to the angle as coordinate axes, calculating differences in image information between the two polar coordinate images while moving one of the two polar coordinate images in a direction of a coordinate axis indicating the angle, and setting information regarding an angle corresponding to the smallest value among values as the result of the calculating as the first traveling information;

the detecting of the second traveling information includes setting information indicating a rotational displacement of the driver as the second traveling information; and

the determining of the traveling state includes determining that the traveling state is abnormal when a different between a value of the first traveling information and a value of the second traveling information exceeds a threshold value.

16. The method of claim 15, wherein the determining of the first traveling information includes setting information the first traveling information as a current rotation angle when the traveling state is determined as being abnormal.

17. A system for detecting a traveling state, comprising:

a control unit including a command receiver receiving a traveling command from a user, a traveling state determiner receiving traveling information and image information and determining a current traveling state of the system, and a compensator correcting, when a current traveling state is abnormal, the abnormal traveling state into a normal state;

a traveling unit including a driver receiving the traveling command from the control unit and driving the system to move, and a traveling information processor performing signal processing on traveling information received from the driver and transmitting a signal processing result to the control unit;

an image receiving unit including an image grabber receiving an image according to a command from the control unit and an image information processor performing signal processing on image information received from the image grabber and transmitting a signal processing result to the control unit; and

a traveling command input unit receiving a traveling command and transmitting the traveling command to the control unit.

18. The system of claim 17, wherein the driver includes a wheel and a motor that rotates the wheel.

19. The system of claim 17, wherein the image grabber includes a camera.

20. The system of claim 19, wherein a lens of the camera faces a direction perpendicular to a plane on which the system moves.

21. The system of claim 17, wherein the traveling command input unit is a traveling function button provided on the system to directly receive a traveling command from a user or a wireless signal receiving module capable of receiving a wireless control signal to receive a traveling command from a remote user.

22. The system of claim 17, wherein the traveling unit includes a wheel, a motor driving the wheel, a gear box transmitting power between the motor and the wheel, and an encoder connected to the motor to process information on a moving distance or a rotation angle of the wheel.

23. A method of determining a rotary movement state, comprising:

receiving a first image and a second image;

converting the first image and the second image into respective first and second polar coordinates;

acquiring a first polar image and a second polar image from the first polar coordinates and the second polar coordinates, respectively; and

detecting a rotation angle by setting a parameter shift_count to adjust a number of sum of squared distance (SSD) calculations which are calculated with respect to 360 angles each at an interval of 1 degree from 0 degrees to 359 degrees.

24. The method of claim 23, wherein the setting includes setting the parameter shift_count to 0, checking whether the shift_count is 360, calculating an SSD using the first and the second polar coordinate images when the shift_count is not 360, shifting the second polar coordinate image by 1 degree and increasing the parameter shift count value by 1 after the calculating the SSD, and returning to the checking, and

wherein the rotation angle is detected when the shift count is 360.

25. The method of claim 24, wherein then the second polar coordinate image is shifted by 1 degree in a positive direction of the X-axis or a negative direction of the X-axis.

26. A method of determining a rectilinear movement state, comprising:

receiving two consecutive images from an image grabber;

calculating a normalized difference between the two consecutive images by calculating a value indicating a normalized image using a difference between the two consecutive images; and

determining whether the normalized difference exceeds a threshold value and, when the normalized difference exceeds a the threshold value, setting a parameter variable to “

TRUE”

indicating rectilinear movement, and when the normalized difference does not exceed the threshold value, setting the parameter variable to “

FALSE”

indicating no rectilinear movement.

27. The method of claim 26, wherein the two images are receive at times separated by a specified interval of time.

28. The method of claim 26, wherein an amount of normalized difference is represented by “

N”

, is used as a reference for determining a rectilinear movement state, and is obtainable by the following equation

$N=\frac{1}{X\times <br><br>Y}<br><br>\underset{x=1}{\overset{X}{\sum <br><br>}}<br><br>\underset{y=1}{\overset{Y}{\sum <br><br>}}<br><br><br><br>A<br><br>\left(x,y\right)-B<br><br>\left(x,y\right)<br><br>,$

wherein X denotes a width of the two consecutive images, Y denotes a height of the two consecutive images, A(x,y) denotes an image information value at a coordinate point (x,y) on one of the two consecutive images before movement, and B(x,y) denotes an image information value at a coordinate point (x,y) on the other of the two consecutive images after the movement.

29. A method of processing traveling information, comprising:

setting a coordinate value (x,y) and an azimuth angle (θ

) of a current position of a robot on an X-Y plane;

calculating an amount of a rectilinear movement of a traveling unit of the system and the amount of a rotary movement of the traveling unit; and

updating the position and the azimuth of the system based on the set position and the set azimuth angle and the amount of calculated rectilinear movement and the amount of calculated rotary movement.

30. The method of claim 29, wherein, after the robot starts traveling, distances that wheels of a driver of the traveling unit rotate are expressible by the following equations, the former equation expressing a distance that a left wheel rotates, the latter equation expressing a distance that a right wheel rotates:

Δ

U_L,i=C_mN_L,i; and


Δ

U_R,i=C_mN_R,i,

wherein N_L,i and N_R,i denote the number of pulses obtained from an encoder included in a traveling information processor of the traveling unit, Δ

U_L,i and Δ

U_R,i respectively denote a distance that each of the left and right wheels respectively rotates in proportion to N_L,i and N_R,i, and C_m denotes a constant used to convert a number of pulses obtained from the encoder into a distance that each wheel rotates and is expressible by the following equation

$C_m=\frac{\mathrm{\pi <br><br>}<br><br>\text{\hspace{1em}<br><br>}<br><br>D_n}{{\mathrm{nC}}_e},$

wherein, D_n denotes a diameter of each wheel, “

n”

denotes a gear ratio between a motor equipped with the encoder and the wheel, and C_e denotes the number of pulses generated by the encoder during a single rotation of the wheel.

31. The method of claim 30, wherein an average distance that a center between the left and right wheels moves is expressible by the following equation

Δ

U_i=(Δ

U_L,i+Δ

U_R,i)/2, and a changed azimuth angle is expressible by the following equation Δ

θ

_i=(Δ

U_R,i−

Δ

U_L,i)/b,

wherein, the equation expressing the changed azimuth angle corresponds to a case where the traveling unit rotates to the left, and “

b”

denotes a distance between the left and right wheels.

32. The method of claim 31, wherein, when a rotary movement is performed, an updated azimuth angle can be expressed by the following equation

θ

_i=θ

_i-1+Δ

θ

_i.

33. The method of claim 31 wherein, when a rectilinear movement is performed, updated coordinates “

x” and

“

y”

are respectively expressible by the following equations;

x_i=x_i-1+Δ

U_i cos θ

_i; and


y_i=y_i-1+Δ

U_i sin θ

_i.

34. A computer-readable storage medium encoded with processing instructions for causing a processor to perform a method of detecting a traveling state, the method comprising:

acquiring two consecutive images and detecting first traveling information from image information regarding each of the two consecutive images;

detecting second traveling information from a driver moving in a direction perpendicular to a direction in which the images are acquired; and

determining the traveling state based on the first traveling information and the second traveling information.

35. A computer-readable storage medium encoded with processing instructions for causing a processor to perform a method of determining a rotary movement state, the method comprising:

receiving a first image and a second image;

converting the first image and the second image into respective first and second polar coordinates;

acquiring a first polar image and a second polar image from the first polar coordinates and the second polar coordinates, respectively; and

detecting a rotation angle by setting a parameter shift_count to adjust the number of sum of squared distance (SSD) calculations which are calculated with respect to 360 angles each at an interval of 1 degree from 0 degrees to 359 degrees.

36. A computer-readable storage medium encoded with processing instructions for causing a processor to perform a method of determining a rectilinear movement state, the method comprising:

receiving two consecutive images from an image grabber;

calculating a normalized difference between the two consecutive images by calculating a value indicating a normalized image using a difference between the two consecutive images; and

determining whether the normalized difference exceeds a threshold value and, when the normalized difference exceeds a the threshold value, setting a parameter variable to “

TRUE”

indicating rectilinear movement, and when the normalized difference does not exceed the threshold value, setting the parameter variable to “

FALSE”

indicating no rectilinear movement.

37. A computer-readable storage medium encoded with processing instructions for causing a processor to perform a method of processing traveling information, the method comprising:

setting a coordinate value (x,y) and an azimuth angle (θ

) of a current position of a robot on an X-Y plane;

calculating an amount of a rectilinear movement of a traveling unit of the system and the amount of a rotary movement of the traveling unit; and

updating the position and the azimuth of the system based on the set position and the set azimuth angle and the amount of calculated rectilinear movement and the amount of calculated rotary movement.