Method and device for evaluating a parameter of a moving object

• US 20050072902A1
• Filed: 04/23/2002
• Published: 04/07/2005
• Est. Priority Date: 04/27/2001
• Status: Active Grant

• Current Assignee: Christian Visee
• Original Assignee: Christian Visee
• Inventors: Visee, Christian
• Granted Patent: US 7,161,133 B2
• Time in Patent Office: Days
• US Class Current: 250/208.100
• CPC Class Codes: G01P 3/68 using optical means, i.e. using infrared, visible, or ultraviolet light G01P3/80 takes precedence ; by reflection of waves G01S17/58
• CPC Class Codes: G01P 3/806 in devices of the type to be classified in G01P3/68

Abstract

A method for measuring a parameter of a movement of an object, in which a series of successive first time-spaced linear images and a second spaced linear image are taken, (a) a first development of first linear images and (b) a second development consisting of at least one second image are formed, and linear images of the first development are compared at least partly with at least a part of a linear image of the second development to determine the part of a spaced linear image of the first development which best corresponds to a part of a linear image of the second development.

Claims

1. A method to characterise, at least partially, a movement of an object relative to a measurement device, this method determining at least one time-function parameter,

in which, by means of a measurement device, from a first determined time, a series of at least three successive first time-spaced linear images are taken in a shot-direction, at a determined time interval, said series forming a first element, and at least, from a second determined time later than the first determined time, at least one second element selected from the group consisting of one single second linear image and a series of second linear images of the object in relative movement is taken, each second linear image being taken in a direction forming an angle with the shot-direction of the first image, each second linear image being spaced from the first linear images,

in which (a) a first development of images in function of time made up of at least a first element and (b) a second development of image made up of at least a second element are formed,

in which at least partially at least one linear image of the first development is compared with at least a part of a linear image of the second development to determine the part of time-spaced linear image of the first development which best corresponds to a part of a linear image of the second development and to determine at least one time-function parameter for which at least a part of the first time-spaced image of the said period best corresponds to a part of a second linear image.

2. The method of claim 1, wherein the first linear images are taken in a first direction and each second linear image or in a second direction, this second direction forming an angle with the first direction of less than 10°

.

4. The method of claim 1,

in which the first element consists of a series of groups of spaced first linear images of the object in relative movement taken from of a first determined time these groups being spaced in time, and in which the second element consists of at least one group of second linear images taken at a time later than the first determined time,

in which (a) the first development of images in function of time consists at least partially of a series of groups of first linear images taken from a first determined time is formed and (b) the second development comprises at least partly a group of second images,

in which at least partially, a part of groups of linear images of the first development is compared with at least a part of at least one group of second linear images of the second development, to determine the part of the group of linear images of the first development which best corresponds to a part of the group of second linear images and to determine a time-function parameter for which at least a part of a group of linear images of the first development best corresponds to a part of the group of second linear images.

5. The method of claim 1,

in which at least for a part of linear images of the first development, a parameter selected from the group consisting of factor of correspondence and a gap in correspondence with at least one second linear image of at least a part of the second development is determined,

in which an optimum parameter selected from the group consisting of the maximum of the factor of correspondence and the minimum of gap of correspondence is determined for determining a first element selected from the group consisting of one single spaced linear image and a group of spaced linear images of the first development which best corresponds to a second element selected from the group consisting of a single linear image and a group of second linear images of the second development.

6. The method of claim 1, wherein at least partially, an element selected from the group consisting of linear images, the first development and the second development is filtered before determining at least the part of time spaced linear image of the first development of which at least a part best corresponds to a part of a linear image of the second development.

7. The method of claim 1, wherein, for at least one linear image taken by a sensor, a compensation is carried out in function of at least one factor selected from the group consisting of distribution of light on the sensor, difference of sensitivities of pixels of linear elements of the sensor, differences and variations bringing about systematic errors in the comparison of linear images.

8. The method of claim 1, wherein the linear images are taken by means of at least one sensor, whereby in order to determine a speed of the object relative to the sensor, the distance between the measurement device and the object in movement relative to the measurement device is determined.

9. The method of claim 8, wherein a relative speed of the object is determined in relation to the sensor from at least one parameter selected from the group consisting of:

the gap of time separating the taking of a first spaced linear image and the taking of a second linear image, for which at least a part of a first spaced linear image best corresponds to a part of a second linear image,

the distance between the object and the sensor,

the angular difference between the shot directions of linear images,

the focal length of a camera taking at least one linear image and

the distance separating two linear sensors taking linear images.

10. The method of claim 1, wherein the object is located at a distance from at least one sensor of a camera taking linear images time-spaced of a period of time, whereby the distance separating the object from the sensor is determined from:

the period of time separating the taking of a first spaced linear image and the taking of a second linear image, for which at least a part of a first spaced linear image best corresponds to a part of a second linear image,

the angular difference between the shot directions of first and second linear images,

the focal length of the camera taking linear images,

the distance separating the two linear sensors taking linear images, and

the relative speed separating the object from the sensor.

11. The method of claim 1, wherein the first linear images formed each of a series of pixels are taken by at least one sensor defining a plane in which the at least one sensor is operative, and in that the object is subject to a relative movement in relation to the at least one sensor parallel to the plane in which the at least one sensor is operative.

12. The method of claim 1, wherein at least a first pair of parallel linear images and a second pair of parallel linear images are taken successively in time, in which at least a first pair of developments of images is formed from the first successive pairs of images and a second pair of developments of images from the second successive pairs of images, in which from the first pair of developments a first time-function parameter is determined and from the second pair of developments a second time-function parameter is determined, and in which this first parameter is compared with this second parameter to determine an accuracy degree selected from the group consisting of degree of exactness and degree of error of the value given to the said first parameter.

13. The method of claim 1, wherein over time a series of images corresponding to segments of a first linear image and of a second linear image are taken, so as to form a series of developments of first segment linear images and a series of second segment linear images, and in which at least partially, at least one image of a development of a first segment image are compared with at least one image of a development of a second segment image.

29. The method of claim 1, in which the first linear images are taken in a first direction and each second linear image in a second direction, this second direction forming an angle with the first direction of less than 5°

.

30. The method of claim 1, in which the first linear images are taken in a first direction and each second linear image in a second direction, this second direction forming an angle with the first direction of less than 3°

.

33. The method of claim 1,

in which the first element consists of a series of groups of spaced first linear images of the object in relative movement taken from of a first determined time, these groups being spaced in time, and in which the second element consists of at least a series of groups of time-spaced second linear images at least taken from a time later than the first determined time and at a determined interval of time,

in which (a) the first development of images in function of time consists at least partially of a series of groups of first linear images taken from a first determined time is formed and (b) the second development comprises at least partially of a series of groups of second linear images in function of time taken from an angle different from the shot direction of the group of first linear images,

in which at least partially, a part of groups of linear images of the first development is compared with at least a part of groups of second linear images of the second development, to determine the part of the group of linear images of the first development which best corresponds to a part of the group of second linear images and to determine a time-function parameter for which at least a part of a group of linear images of the first development best corresponds to a part of the group of second linear images.

34. The method of claim 1, in which the linear images are taken by means of at least one sensor, whereby in order to determine an acceleration of the object relative to the sensor, the distance between the measurement device and the object in movement relative to the measurement device is determined.

35. The method of claim 1, in which the linear images are taken by means of at least one sensor, whereby in order to determine an acceleration of the object relative to the sensor, the measurement device is placed at a known distance, at least for a given time, relative to the object in movement relative to the measurement device.

36. The method of claim 1, in which the linear images are taken by means of at least one sensor, whereby in order to determine an speed of the object relative to the sensor, the measurement device is placed at a known distance, at least for a given time, relative to the object in movement relative to the measurement device.

37. The method of claim 1, in which the second linear images formed each of a series of pixels are taken by at least one sensor defining a plane in which the at least one sensor is operative, and in that the object is subject to a relative movement in relation to the at least one sensor parallel to the plane in which the at least one sensor is operative.

38. The method of claim 1, in which over time a series of images corresponding to segments distant from each other, of a first linear image and of a second linear image are taken, so as to form a series of developments of first segment linear images and a series of second segment linear images, and in which at least partially, several first linear segment images are compared with several second linear segment images.

3. A method to characterise, at least partially, a movement of an object relative to a measurement device, this method determining at least one time-function parameter,

wherein by means of a measurement device, from a first determined time, a series of at least three successive first linear images are taken in a shot direction, at a determined time interval, and at least, from a second determined time later than the first determined time, a series of second linear images of the object in relative movement are taken, said second linear images being taken in a direction forming an angle with the shot-direction of the first images and being spaced from the first images,

wherein (a) a first development of images in function of time consisting of at least a series of first linear images spaced in time taken from the first determined time and (b) a second development of images made up of a series of second spaced linear images taken at a determined time interval are formed, and

wherein at least partially, at least one linear image of the first development is compared with at least a part of at least one linear image of the second development to determine the part of at least one time-spaced linear image of the first development which best corresponds to a part of one linear image of the second development and to determine at least one time gap for which at least a part of a first spaced linear image best corresponds to a part of a second linear image.

14. A measurement device for establishing a method to characterise, at least partially, a movement of an object relative to a measurement device, this method determining at least one time-function parameter,

in which, by means of the measurement device, from a first determined time, a series of at least three successive first time-spaced linear images are taken in a shot-direction, at a determined time interval, said series forming a first element, and at least, from a second determined time later than the first determined time, at least one second element selected from the group consisting of one single second linear image, a series of second linear images of the object in relative movement is taken, each second linear image being taken in a direction forming an angle with the shot-direction of the first image, each second linear image being spaced from the first linear images,

in which (a) a first development of images in function of time made up of at least a first element and (b) a second development of image made up of at least a second element are formed,

in which at least partially at least one linear image of the first development is compared with at least a part of a linear image of the second development to determine the part of time-spaced linear image of the first development which best corresponds to a part of a linear image of the second development and to determine at least one time-function parameter for which at least a part of the first time-spaced image of the said period best corresponds to a part of a second linear image,

said device including at least:

a sensor set taking at least one first linear image by a first sensor means and at least one series of second linear images by a second sensor means, in particular taken at successive times, the said second linear images being taken from a different angle relative to the first linear image,

a means generating a series of first images spaced in time,

a comparison device receiving signals from the sensor set and from the means generating a series of first images spaced in time, this comparison device comparing, at least partially, the series of first spaced images with at least one second linear image and determining, for at least a part of the series of first spaced images a parameter selected from the group consisting of a factor of correspondence and a discrepancy of correspondence with at least a part of a second linear image, this comparison device being programmed for determining a time parameter corresponding to an optimum parameter selected from the group consisting of maximum of the factor of correspondence and minimum of discrepancy of correspondence between at least a part of a first linear image spaced in time and at least a part of a second linear image.

15. The device of claim 14, wherein the first sensor means is arranged to take at least one linear image in a first direction, while the second sensor means is arranged to take at least one linear image in a second direction, this second direction forming an angle with the said first direction of less than 10°

.

16. The device of claim 15, wherein the sensor set takes linear images in the form of a set of pixels and attributes to each pixel a parametric value, this set moreover comprising a means of correction of the parametric value attributed to pixels of at least one image selected from the group consisting of at least one second linear image and first linear images spaced in time, in function of at least one parameter selected from the group consisting of distribution of light, differences and variations bringing about systemic errors in the comparison of the images and differences of sensitivity of sensor means.

17. The device of claim 14, wherein the device comprises a sensor, at least bi-linear, defining a plane of image reception and focalisation lens focalising an image of an object in movement relative to the said reception plane of the sensor.

18. The device of claim 14, which comprises:

a sensor comprising at least a first means receiving a first series of rows of pixels or lines of an image and a second means receiving a second series of rows of pixels or lines of the image at least partially distanced from the pixels of the first row or line,

a delay memory which memorises, at least partially, the first series of rows of pixels or lines and which emits, with pre-determined delays, the values memorised corresponding to that first series of rows of pixels or lines,

a comparison device receiving signals from the sensor corresponding to the values of the pixels of the second series of rows or lines over time, and signals coming from the delay-memory, this comparison device being programmed for determining the delay to attribute to the first series of rows of pixels or lines for which the values memorised corresponding to the said first series of rows of pixels or lines best correspond to the values of the second series of rows of pixels or lines.

19. The device of claim 18, wherein the comparison device determines, for delays pre-determined by the delay-memory, a difference of value of pixels between the pixels of the first row taken at different moments and the value of the pixels of the second row, and emits signals comprising the differences of values of pixels associated to pre-determined delays to a processor which determines, by calculation step selected from the group consisting of interpolation, extrapolation, approximation, successive iteration, and combinations thereof, the delay for which the difference of value of pixels is minimal.

20. The device of claim 14, which comprises a focalisation lens including a cylinder lens.

21. The device of claim 14, which comprises distinct focalisation lenses for each means sensing a row of pixels.

22. The device of claim 14 which comprises at least one filter for the linear images.

23. The device of claim 14, which comprises a means of checking the quality of the parameter determined by the processor, this means advantageously comprising a means to determine a factor of quality from signals coming from the processor and an attenuator receiving the factor of quality determined and weighting the parameter determined by the processor in function of the factor of quality.

24. The device of claim 14, which comprises a low-channel filter to attenuate variations selected from the group consisting of errors due to the tri-dimensional form of the object in relative movement and high-frequency noises introduced into the measurements.

25. The device of claim 14, wherein the sensor set receives signals coming from the comparison device.

26. The device of claim 14, wherein the sensor set takes at least one first linear image and at least one second linear image, said first and second linear image being selected from the group consisting of images in at least two colours and linear RGB images.

27. The device claim 26, wherein the sensor set comprises at least 2 linear sensors.

39. The device of claim 14, in which the first sensor means is arranged to take at least one group of linear images in a first direction, while the second sensor means is arranged to take at least one group of linear images in a second direction, this second direction forming an angle with the said first direction of less than 10°

.

40. The device of claim 14, in which the first sensor means is arranged to take at least one linear image in a first direction, while the second sensor means is arranged to take at least one linear image in a second direction, this second direction forming an angle with the said first direction of less than 5°

.

41. The device of claim 14, in which the first sensor means is arranged to take at least one linear image in a first direction, while the second sensor means is arranged to take at least one linear image in a second direction, this second direction forming an angle with the said first direction of less than 3°

.

42. The device of claim 18, in which the distance separating these first and second series of rows or lines is a multiple of the size of a pixel, these rows or lines being parallel to each other.

43. The device of claim 18, in which the comparison device is linked to a processor to determine the delay to attribute to the first series of rows of pixels or lines for which the values memorised corresponding to the said first series of rows of pixels or lines best correspond to the values of the second series of rows of pixels or lines.

44. The device of claim 14, which comprises several filters for the linear images.

45. The device of claim 14, which comprises an processing means selected from the group consisting of a processor determining a time parameter, an attenuator adapting the frequency of shots of linear images, and an attenuator adapting an increment of delay between two shots of linear images, and in which the sensor set receives signals coming from at least one processing means.

46. The device of claim 14, in which the sensor set comprises at least one matrix sensor which is addressable line by line.

28. (new) A method to characterise, at least partially, a movement of an object relative to a measurement device, this method determining at least one time-function parameter,

in which, by means of a measurement device, from a first determined time, a series of at least three successive first time-spaced linear images are taken in a shot-direction, at a determined time interval, said series forming a first element, and at least, from a second determined time later than the first determined time, at least one second element selected from the group consisting of one single second linear image and a series of second linear images of the object in relative movement is taken, each second linear image being taken in a direction forming an angle with the shot-direction of the first image, each second linear image being spaced from the first linear images,

in which (a) a first development of images in function of time made up of at least a first element and (b) a second development of image made up of at least a second element are formed,

in which at least partially linear images of the first development are compared with at least a part of linear images of the second development to determine the part of time-spaced linear images of the first development which best correspond to a part of linear images of the second development and to determine at least one time-function parameter for which at least a part of the first time-spaced images of the said period best corresponds to a part of second linear images.

31. A method to characterise, at least partially, a movement of an object relative to a measurement device, this method determining at least one time-function parameter,

in which by means of a measurement device, from a first determined time, a series of at least three successive first linear images are taken in a shot direction, at a determined time interval, and at least, from a second determined time later than the first determined time, a series of second linear images of the object in relative movement are taken, said second linear images being taken in a direction forming an angle with the shot-direction of the first images and being spaced from the first images,

in which (a) a first development of images in function of time consisting of at least a series of first linear images spaced in time taken from the first determined time and (b) a second development of images made up of a series of second spaced linear images taken at a determined time interval are formed, and

in which at least partially, linear images of the first development are compared with at least a part of linear images of the second development to determine the part of time-spaced linear images of the first development which best corresponds to a part of linear images of the second development and to determine at least one time gap for which at least a part of a first spaced linear images best correspond to a part of second linear images.

32. The method of claim 31, in which the time gap is expressed as a number of lines of pixels.