Apparatus for measuring an object based on spatio-temporally derivated image signals

• US 4,839,824 A
• Filed: 07/21/1987
• Issued: 06/13/1989
• Est. Priority Date: 07/22/1986
• Status: Expired due to Fees

• Current Assignee: Yaskawa Corporation (Yaskawa Electric Corporation)
• Original Assignee: Suncom, Inc.
• Inventors: Ando, Shigeru
• Primary Examiner(s): Lall, Parshotam S.
• Assistant Examiner(s): Ramirez, Ellis B.
• Application Number:
  US07/076,436
• Time in Patent Office: 693 Days
• Field of Search: 364/516, 364/560, 364/561, 364/562, 364/900, 364/555, 364/565, 358/96, 358/105, 358/107, 382/65, 382/41, 382/49, 901/47, 378/901
• US Class Current: 702/166
• CPC Class Codes: G01B 11/245 using a plurality of fixed, simultaneously operating transducers G01B11/2408 - G01B11/2425, G01B11/255 take precedence
• CPC Class Codes: G06T 7/269 using gradient-based methods

Abstract

A measuring apparatus which makes use of spatio-temporal derivative method has a sensor which may be a pair of cameras for picking up images of a three-dimensional object, computing unit for processing the signals by applying spatio-temporal derivative method to the signals representing the images so as to determine physical amounts of the object such as heights of different regions on an object and self-estimation values such as values indicative of validity of the height data, judging unit for judging the validity of the physical amounts determined by the computing means on the basis of the self-estimation values, and control unit for varying, when there is any physical amount having low validity, the measuring condition of the sensor such as the distance between the sensor and the object so as to enable the sensor to obtain the signals again, while restarting the computing means and the judging means. The final measuring result such as the three-dimensional image can be formed by utilizing only the valid data obtained with a plurality of measuring conditions.

Claims

1. An apparatus for measuring an object, comprising:

sensor means for picking up signals representing data concerning an object to be measured;

computing means for spatio-temporally differentiating said signals so as to determine physical amounts of said object and to determine self-estimation values, of a type that said physical amounts include an associated error to which said self-estimation values are proportional;

judging means for juding the validity of the physical amounts determined by said computing means, on the basis of said self-estimation values; and

control means for varying, in response to a judgment of any physical amount having a low validity, a measuring condition of said sensor means so as to enable said sensor means to obtain said signals again, while re-starting said computing means and said judging means.

2. A measuring apparatus according to claim 1, wherein said control means synthesizes a physical value having a high degree of validity obtained by picking up said signals for a plurality of times thereby to supply a measuring result.

3. A three-dimensional measuring apparatus for detecting a three-dimensional image of an object, comprising:

a pair of image pickup devices having optical axes which intersect each other at a point on a predetermined reference plane, said devices producing, respectively, a left image signal and a right image signal;

computing means for computing, on the basis of said left and right image signals, a sum signal representing the sum of said left and right image signals, a difference signal representing a difference between said left and right image signals and a sum differentiation signal obtained by differentiating said sum of said left and right image signals, said computing means being further adapted to determine;

(a) a relative height of each region of said object from said reference plane, said relative height including an associated error, and

(b) a self-estimation value for each of said regions, said self-estimation value being proportional to said associated error and used as a criterion for judgment as to whether the determined relative height is valid as a measurement data;

judging means for judging a validity of said relative height for each of said regions on the basis of said self-estimation value; and

synthesizing means for synthesizing the three-dimensional image of said object by using said relative height which have been judged by said judging means as being valid.

4. A measuring apparatus according to claim 3, further comprising:

convergence angle driving means for controlling a convergence angle formed between the optical axes of said pair of image pickup devices so as to shift said reference plane with respect to a depth of said object; and

control means for activating, when said relative height of said object from said reference plane includes data of a low validity, said convergence angle driving means so as to shift said reference plane and for picking up image signals on the basis of shifted reference plane from said pair of a image pickup devices, while driving said computing means, said judging means and said synthesizing means;

whereby said three-dimensional image of said object is determined on the basis of said relative height having a high degree of validity obtained from the image signals on the basis of the respective positions of said reference plane.

5. A measuring apparatus according to claim 3, further comprising:

reference plane shifting means for electrically controlling said image signal from said pair of image pickup devices so as to shift said reference plane with respect to a depth of said object;

control means for picking up, when said relative height of said object from said reference plane includes data of a low validity, image signals from said pair of image pickup devices on the basis of shifted reference plane shifted by said reference plane shifting means, while driving said pair of image pickup devices so as to shift said reference plane with respect to a depth of said object; and

control means for activating, when said relative height of said object from said reference plane includes data of a low validity, said convergence angle driving means so as to shift said reference plane and for picking up image signals on the basis of shifted reference plane from said pair of said image pickup devices, while driving said computing means, said judging means and said synthesizing means;

whereby said three-dimensional image of said object is determined on the basis of said relative height having high degree of validity obtained from the image signals on the basis of the respective positions of said reference plane.

6. A three-dimensional measuring apparatus according to claim 3, wherein said synthesizing means weights said relative height which has been judged as being valid in accordance with a degree of its validity, thereby synthesizing the three-dimensional image of said object.

7. A measuring apparatus according to claim 6, further comprising:

convergence angle driving means for controlling a convergence angle formed between the optical axes of said computing means, said judging means and said computing means;

whereby said three-dimensional image of said object is determined on the basis of said relative height having high degree of validity obtained from the image signals on the basis of the respective positions of said reference plane.

8. A measuring apparatus according to claim 6, further comprising:

reference plane shifting means for electrically controlling said image signal from said pair of image pickup devices so as to shift said reference plane with respect to a depth of said object;

control means for picking up, when said relative height of said object from said reference plane includes data of a low validity, image signals from said pair of image pickup devices on the basis of shifted reference plane shifted by said reference plane shifting means, while driving said computing means, said judging means and said computing means;

whereby said three-dimensional image of said object is determined on the basis of said relative height having high degree of validity obtained from the image signals on the basis of the respective positions of said reference plane.

9. A measuring apparatus for measuring velocity distribution of a moving object, comprising:

an image pickup device for outputting image signals for each of successive frames at a predetermined time interval;

computing means for computing a time-differentiated value of said image signals and a spatially-differentiated value of said image signals, and for computing, on the basis of said time- and spatially-differentiated values;

(a) velocity vectors of the respective regions of said moving object, said velocity vectors including an associated error, and

(b) a self-estimation value for each of said regions, said self-estimation value being proportional to said associated error and used as a criterion for a judgment as to whether each of said velocity vectors determined by said computing means constitutes a valid data;

judging means for judging a validity of said velocity vectors for each of said regions on the basis of said self-estimation value; and

velocity synthesizing means for synthesizing the velocity distribution of said moving object by using said velocity vectors which have been judged as being valid by said judging means.

10. A measuring apparatus according to claim 9, wherein said time-differentiated value is computed on the basis of image signals from two successive frames.

11. A measuring apparatus according to claim 10, further comprising:

frame time interval control means for varying said time interval; and

driving control means for operating, when said velocity vectors obtained on the basis of the image signals at said predetermined interval includes data of a low validity, said frame time interval control means to control the time interval of said frames, and for picking up image signals by said image pickup device on the basis of new time interval, while driving said computing means, said judging means and said velocity synthesizing means;

whereby said velocity distribution of said moving object is synthesized by the velocity vectors of high validity obtained at said varied time intervals.