Laser surface characteristic measuring

• US 5,815,593 A
• Filed: 10/10/1995
• Issued: 09/29/1998
• Est. Priority Date: 10/10/1995
• Status: Expired due to Fees

• Current Assignee: Smiss Technology Company Limited
• Original Assignee: Smiss Technology Company Limited
• Inventors: Remis, Steven J., Shaum, Loren E., McVay, Allen K.
• Primary Examiner(s): KELLEY, CHRISTOPHER S
• Application Number:
  US08/544,403
• Time in Patent Office: 1,085 Days
• Field of Search: 382/154, 382/108, 382/141, 382/143, 382/151, 382/152, 382/184, 382/217, 382/218, 382/286, 382/289, 348/42, 348/47, 348/86, 348/92, 348/93, 348/94, 348/95, 348/124, 348/125, 348/128, 348/130, 364/420, 364/491, 250/223 B, 250/559.39, 250/559.46, 356/1237, 356/376, 356/394, 356/396, 29/729, 29/739
• US Class Current: 382/154
• CPC Class Codes: G06T 2207/10021 Stereoscopic video; Stereoscopic image sequence
• CPC Class Codes: G06T 7/579 from motion
• CPC Class Codes: G06T 7/593 from stereo images

Abstract

A high speed method and apparatus for accepting and rejecting an object by identifying specific surface features of interest of an object includes providing at least one non-contact sensor capable of measuring a characteristic of a surface and a transporter system for creating relative motion between the sensor and an object while repetitively making measurements of a surface of the object with multiple readings being taken with the sensor at each of multiple locations in order to create a data set. A data analysis system mathematically processes the surface characteristic data and positional data into surface feature data which represents three-dimensional surface features of the object. The data analysis system correlates the surface feature data with data representative of ideal surface features of an object in order to determine an amount of deviation of the measured surface feature data from data representative of ideal surface features to accept or reject the object by determining whether the amount of deviation is within a provided limit.

Claims

1. A high speed method of accepting and rejecting an object by identifying specific three-dimensional surface features of interest of an object, including:

providing at least two sensors configured to make measurements of opposite surfaces of a common wall;

creating relative motion between said sensor and the object while repetitively making measurements of surface characteristics in order to create a data set wherein said data set includes a plurality of measurements made at each position on the object and positional data;

extracting from said data set a subset of data that represents surface features of interest of the object by mathematically manipulating said data set to identify three-dimensional surface features of interest of the object on each of said opposite surfaces;

providing a set of relevant surface feature data and a limit of deviation from the surface feature data which represents an acceptable object;

correlating said subset of data that represents surface features of interest of the object with said set of relevant surface feature data in order to determine an amount of deviation of the measured features of interest from the relevant surface feature data; and

accepting or rejecting said object in response to said correlating the specified tolerance by determining whether the amount of deviation is within the provided limit.

3. The method of claim 1 including identifying an orientation of said object and reorienting said object in response to said identifying prior to said steps of creating, extracting, correlating and accepting or rejecting.

4. The method of claim 3 wherein said identifying an orientation includes performing said steps of creating, extracting, providing and correlating in order to identify whether the amount of deviation from the relevant surface feature data of a particular surface feature of the object which correlates with the orientation of the object is within a provided limit.

5. The method of claim 1 wherein said mathematically manipulating includes creating an n-by-m matrix and processing said matrix to obtain said surface features of interest, where n is the number of measurements made at each position and where m is the number of positions.

6. The method of claim 1 wherein said step of creating relative motion includes moving the object in at least two independent coordinates.

7. The method of claim 1 wherein said step of creating relative motion includes rotating the object about an axis.

8. The method of claim 7 wherein said step of creating relative motion further includes moving the sensor along said axis.

17. The method of claim 1 wherein said step of creating relative motion includes rotating the object about an axis.

18. The method of claim 1 wherein one of said surfaces defines threads.

19. The method of claim 18 wherein said threads are internal threads.

20. The method of claim 1 wherein the surface features of interest are identified on non-planar surfaces.

21. The method of claim 4 wherein the surface features of interest which correlate with the orientation of the object are identified on non-planar surfaces.

2. A high speed non-contact inspection apparatus, comprising:

at least two sensors configured to measure characteristics of opposite surfaces of a common wall;

a transporter system for causing relative motion between said at least two sensors and an object;

a high speed data acquisition system for making multiple readings from said at least two sensors at each of multiple locations on an object in order to provide surface characteristic data; and

a data analysis system which receives said surface characteristics data from said data acquisition system and positional data from said transporter and mathematically processes said surface characteristic data and said positional data into three-dimensional surface feature data which represents surface features of the object; and

wherein said data analysis system correlates said surface feature data with data representative of ideal surface features of an object in order to determine an amount of deviation of the measured surface feature data from the data representative of ideal surface features and accepts or rejects the object by determining whether the amount of deviation is within a provided limit.

9. The apparatus in claim 2 wherein said transporter system, said data acquisition system, and said data analysis system each include a controller for substantially independent control of the associated system.

10. The apparatus in claim 2 wherein said transporter system is responsive to said data analysis system for establishing a particular orientation of the object.

11. The apparatus in claim 10 wherein said transporter system reorients the object after initial identification of particular surface features of the object.

12. The apparatus is claim 2 wherein said transporter system transports the object.

13. The apparatus in claim 12 wherein said transporter system transports the object in at least two independent axes.

14. The apparatus in claim 12 wherein said transporter system rotates the object about an axis.

15. The apparatus in claim 14 wherein said transporter system further transports the sensor along said axis.

16. The apparatus in claim 2 wherein said data analysis system mathematically processes said surface characteristic data and said positional data by creating an n-by-m matrix, where n is the reading at each location and m is the location, and processing said matrix to obtain said surface character data.