One dimensional image visual system for a moving vehicle

• US 4,905,151 A
• Filed: 03/07/1988
• Issued: 02/27/1990
• Est. Priority Date: 03/07/1988
• Status: Expired due to Fees

• Current Assignee: Transitions Research Corp.
• Original Assignee: Transitions Research Corp.
• Inventors: Evans, John M. Jr., Weiman, Carl F. R.
• Primary Examiner(s): Lall, Parshotam S.
• Assistant Examiner(s): Black, Thomas G.
• Application Number:
  US07/165,015
• Time in Patent Office: 722 Days
• Field of Search: 364/424.02, 364/443, 364/513, 364/456, 364/449, 180/167, 180/168, 180/169, 382/22
• US Class Current: 701/28
• CPC Class Codes: G05D 1/0251 extracting 3D information from a plurality of images taken from different locations, e.g. stereo vision stereoscopic image analysis H04N13/00; depth recovery from images G06T7/593
• 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 1/027 comprising intertial navigation means, e.g. azimuth detector inertial navigation G01C21/16; inertial navigation combined with non-inertial navigation instruments G01C21/165
• 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: G05D 1/0274 using mapping information stored in a memory device navigation using map-matching G01C21/30

Abstract

A vision system for a mobile robot 10 comprises an optical sensor subsystem 20 which generates a substantially one dimensional image of an environment, a signal processing subsystem 24 for extracting and enhancing significant vertical visual features from the one dimensional image and a feature processing system 26 which analyses rapidly and in real time the extracted features for use by a control system 28 for navigation of the robot. The optical sensor may be a line scan camera having a plurality of outputs which relate to brightness values received from the environment. Triangulation, optical flow and optical flow with log transforms methods are disclosed for processing the one dimensional image data to yield azimuth and/or distance to an object within the environment. Also disclosed is a binocular vision system which generates two, one dimensional images and a method of processing same.

Claims

1. A vision system for a mobile vehicle comprising:

means, having a substantially planar field of view of an environment, for generating a substantially linear, one-dimensional image of the environment through which a mobile vehicle moves, the environment including at least one object, said image generating means having an output signal for expressing a characteristic of the image at a plurality of points along the substantially one dimensional image; and

means, coupled to said output signal, for processing said output signal to determine at least one characteristic associated with a position of the object relative to a position of said mobile vehicle within the environment.

2. A vision system as defined in claim 1 wherein said at least one determined characteristic is an azimuth angle between said mobile vehicle and the object.

3. A vision system as defined in claim 1 wherein said at least one determined characteristic includes a distance to the object relative to the vehicle.

4. A vision system as defined in claim 1 and further comprising:

means, coupled to said processing means, for varying the position of said mobile vehicle relative to the object as a function of said at least one determined characteristic.

5. A vision system as defined in claim 4 wherein said mobile vehicle moves across a substantially planar surface and wherein said field of view is substantially parallel with the surface.

6. A vision system as set forth in claim 1 and further comprising means, coupled to the vehicle, for illuminating the environment.

7. A vision system as set forth in claim 1 wherein said means for generating comprises a linear array of radiation detectors that view the environment through a cylindrical lens.

8. A vision system as set forth in claim 1 wherein said means for generating comprises a two-dimensional array of radiation detectors having detector outputs from a given row or column combined such that a substantially one-dimensional image is obtained.

9. A vision system for a vehicle comprising:

optical sensor means for generating a substantially linear, one dimensional image of an environment through which the vehicle is to move, the environment including one or more features, said sensor means having a first output signal expressive of edge boundaries of the one or features appearing within the substantially one dimensional image;

signal processing means coupled to said first output signal for processing said signal for detecting the edge boundaries associated with the one or more features, said signal processing means having a second output signal expressive at least of the detected edge boundaries; and

feature processing means coupled to said second output signal for generating a third output signal expressive at least of a positional relationship between said vehicle and the one or more features within the field of view.

10. A vision system as defined in claim 9 wherein said optical sensor means comprises:

a radiation detector; and

means for sequentially activating the radiation detector for generating a plurality of output signals, each of the output signals being expressive of the detected radiation at a point along said substantially linear, one-dimensional image.

11. A vision system as defined in claim 10 wherein said substantially one-dimensional image is orientated substantially parallel to the surface.

12. A vision system as defined in claim 11 wherein said radiation detector comprises an array of visible radiation detectors.

13. A vision system as defined in claim 11 wherein said radiation detector comprises an array of infrared radiation detectors.

14. A vision system as defined in claim 9 wherein the first output signal is expressive of brightness values along the substantially one dimensional image.

15. A vision system as defined in claim 9 wherein the first output signal is expressive of color values along the substantially one dimensional image.

16. A vision system as defined in claim 9 wherein the first output signal is expressive of a polarization angle of radiation along the one dimensional image.

17. A vision system as defined in claim 9 wherein said positional relationship is an azimuth angle between said vehicle and at least one of said one or more features.

18. A vision system as defined in claim 9 wherein said positional relationship is a distance between said vehicle and at least one of said one or more features.

19. A vision system as defined in claim 9 wherein said vehicle comprises:

drive means for moving said vehicle across a surface; and

control means for controlling the operation of said drive means, said control means being coupled to said third output signal and responsive thereto for controlling the operation of said drive means at least in response to said positional relationship between said vehicle and the one or more features within the substantially one-dimensional image.

20. A vision system as defined in claim 19 wherein said vehicle further comprises:

encoder means, coupled to said drive means and responsive to the operation thereof, for outputting to said control means a signal expressive of a distance travelled by said vehicle between a first and a second point on the surface; and

means, coupled to said encoder means output signal, for outputting to said feature processing means a signal expressive of a velocity of said vehicle between the first and the second point.

21. A mobile robot comprising:

platform means;

drive means coupled to said platform means for moving said platform means relative to a surface;

control means, coupled to said platform means, for providing control signals to said drive means for controlling the movement of said platform means; and

vision means, coupled to said platform means, for generating vision signals related to one or more features within an environment through which said platform means moves, said vision means comprising;

optical sensor means for generating a substantially linear, one dimensional image of an environment through which the robot moves, the environment including one or more features, said sensor means having a first output signal expressive of edge boundaries of the one or features appearing within the substantially one dimensional image;

signal processing means coupled to said first output signal for processing said signal for detecting the edge boundaries associated with the one or more features, said signal processing means having a second output signal expressive at least of the detected edge boundaries; and

feature processing means coupled to said second output signal for generating a third output signal expressive at least of a positional relationship between the robot and the one or more features within the field of view.

22. A mobile robot as defined in claim 21 wherein said optical sensor means comprises:

a radiation detector; and

means for sequentially activating the radiation detector for generating a plurality of output signals, each of the output signals being expressive of the detected radiation at a point along said substantially linear, one-dimensional image.

23. A mobile robot as defined in claim 22 wherein said substantially one-dimensional image is orientated substantially parallel to a surface over which the robot moves.

24. A mobile robot as defined in claim 23 wherein said optical sensor means comprises an array of radiation detectors.

25. A mobile robot as defined in claim 21 and further comprising:

encoder means, coupled to said drive means and responsive to the operation thereof, for outputting to said control means a signal expressive of a distance travelled by said robot between a first and a second point on the surface; and

means, coupled to said encoder means output signal, for outputting to said feature processing means a signal expressive of a velocity of said robot between the first and the second point.

26. A mobile robot as defined in claim 21 wherein the optical sensor means further comprises a cylindrical lens disposed in front of said radiation detector for emphasizing vertical components of said features.

27. For a vehicle moving over a surface at a velocity along a path, a method of determining an x-y position of an object disposed relative to the surface where x is a distance to the object parallel to the path and y is a distance to the object perpendicular to the path, comprising the steps of:

at a first time t.sub.(i) viewing the object to generate a substantially one-dimensional image of the object, the substantially one dimensional image being orientated in a substantially parallel manner with the surface;

determining a first position of the object within the one dimensional image relative to a first position within the one-dimensional image which coincides with the path;

converting the difference between the first image position and the first path position to a tangent of an angle (A), where A is the angle between the object and the path at time t.sub.(i) ;

at a second time t.sub.(i+1) viewing the object to generate a substantially one-dimensional image of the object, the substantially one dimensional image being orientated in a substantially parallel manner with the surface;

determining a second position of the object within the one dimensional image relative to a second position within the one-dimensional image which coincides with the path;

converting the difference between the second image position and the second path position to a tangent of an angle (B), where B is the angle between the object and the path at time t.sub.(i+1) ; and

calculating the distance x in accordance with the equation

x=r*tan(B)/(tan(B)-tan(A));

and calculating the distance y in accordance with the equation

y=x*tan(A)

where r=u*t, where t is the difference in time between t.sub.(i) and t.sub.(i+1).

28. A binocular vision system for a vehicle comprising:

optical sensor means for detecting radiation emanating from one or more features within an environment of a vehicle, said sensor means generating two substantially one-dimensional images of the environment, the images being substantially parallel one to another and each having an image output signal expressive of a characteristic of the detected radiation at a plurality of points along the associated substantially one dimensional image, said vehicle being disposed upon a surface and said one-dimensional images being disposed at a predetermined orientation to the surface;

signal processing means coupled to said image output signals for processing said signals for detecting a component or components of each of said image output signals associated with said one or more features, said signal processing means having an output signal expressive at least of the detected component

or components of the image output signals; and

feature processing means coupled to said signal processing means output signal for generating an output signal expressive at least of a positional relationship between said vehicle and the one or more features within the environment of the vehicle.

29. A binocular vision system as defined in claim 28 wherein said optical sensor means comprises:

a radiation detector; and

means for sequentially activating the radiation detector for generating a plurality of output signals, each of the output signals being expressive of the radiation at a point along at least one of said substantially one-dimensional images.

30. A binocular vision system as defined in claim 28 wherein each of said substantially one-dimensional images is orientated substantially parallel to the surface.

31. A binocular vision system as defined in claim 28 wherein said optical sensor means comprises a first and a second array of radiation detectors, the first and second arrays being substantially linear arrays which are disposed parallel one to another.

32. A binocular vision system as defined in claim 28 wherein said optical sensor means comprises an array of infrared radiation detectors.

33. For a vehicle moving over a surface along a path, a method of determining an x-y position of an object disposed relative to the surface where x_o is an unknown distance to the object parallel to the path and y is an unknown distance to the object perpendicular to the path, comprising the steps of:

viewing the object from a first viewpoint and from a second viewpoint to generate two substantially one-dimensional images of the object, the substantially one dimensional images being orientated in a substantially parallel manner one to another and also with the surface;

determining a position (p) of the object within each of the one dimensional images relative to a position within each of the one-dimensional images which coincides with the path;

calculating the distance x_o in accordance with the equation

x_o =D/(p1-p2);

and calculating the distance y in accordance with the equation

y=D*p1/(p1-p2);

where p1 and p2 are each the determined position within each of the fields of view in perspective projection of the object onto the substantially one dimensional image and wherein D is a distance between the first viewpoint and the second viewpoint.

34. For a vehicle moving over a surface at a velocity along a path, a method of determining for an object disposed relative to the surface an azimuth angle of the object relative to the path, comprising the steps of:

at a first time t.sub.(i) viewing the object to generate a substantially one-dimensional image of the object, the substantially one dimensional image being orientated in a substantially parallel manner with the surface;

determining a first position of the object within the one dimensional image relative to a first position within the one-dimensional image which coincides with the path; and

converting the difference between the first image position and the first path position to a tangent of an angle (A), where A is the angle between the object and the path at time t.sub.(i).

35. For a vehicle moving over a surface at a velocity along a path, a method of determining an x-y position of an object disposed relative to the surface where x_o is an unknown distance to the object parallel to the path and y is an unknown distance to the object perpendicular to the path, comprising the steps of:

viewing the object to generate a substantially one-dimensional image of the object, the substantially one dimensional image being orientated in a substantially parallel manner with the surface;

determining a position of the object within the one dimensional image relative to a position within the one-dimensional image which coincides with the path;

determining the velocity (v) of the vehicle along the path; and

calculating the distance x_o in accordance with the equation

x_o =v*p/(dp/dt); and

calculating the distance y in accordance with the equation

y=v*p /(dp/dt);

where p is a position within the field of view in perspective projection of the object onto the substantially one dimensional image.

36. For a vehicle moving over a surface at a velocity along a path, a method of determining an x-y position of an object disposed relative to the surface where x_o is an unknown distance to the object parallel to the path and y is an unknown distance to the object perpendicular to the path, comprising the steps of:

viewing the object to generate a substantially one-dimensional image of the object, the substantially one dimensional image being orientated in a substantially parallel manner with the surface;

determining a position of the object within the one dimensional image relative to a position within the one-dimensional image which coincides with the path;

determining the velocity (v) of the vehicle along the path; and

calculating the distance x_o in accordance with the equation

x_o =v/(dq/dt); and

calculating the distance y in accordance with the equation

y=(v*exp(q))/(dq/dt);

where q is a natural logarithm of p and wherein p is a determined position within the field of view in perspective projection of the object onto the substantially one dimensional image.