Method and apparatus for contact free measurement of periodically moving objects

• US 20080037032A1
• Filed: 08/08/2006
• Published: 02/14/2008
• Est. Priority Date: 08/08/2006
• Status: Active Grant

• Current Assignee: Tyrex Services Group, Ltd.
• Original Assignee: Tyrex Services Group, Ltd.
• Inventors: Lutz, Ron, Crowell, Brian, Scogin, James
• Granted Patent: US 7,495,777 B2
• Time in Patent Office: Days
• US Class Current: 356/603
• CPC Class Codes: G01B 11/25 by projecting a pattern, e.g. one or more lines, moiré fringes on the object G01B11/255 takes precedence ; image analysis for depth or shape recovery G06T7/50

Abstract

A method and apparatus is described for contact-free 3 dimensional-measuring of a moving object with periodic motion. The method and apparatus makes use of the projection of a defined intensity pattern onto the moving object and the recording and analysis of a reflected pattern from the object wherein the intensity pattern projection is synchronized to a characteristic periodic frequency period or sub-period of the moving object.

Claims

1. A method for contact-free 3 dimensional-measuring of a moving object with periodic motion, comprising the steps of:

a. projecting a defined intensity pattern onto said moving object to create a deflected projected pattern corresponding to the shape of said moving object;

b. recording said deflected projection pattern with a camera; and

c. evaluating with a computer supported software evaluation protocol the created deflected projection pattern corresponding to the shape of said moving object;

wherein said projecting of defined intensity patterns onto said moving object is synchronized to a characteristic periodic frequency period or sub-period of said moving object.

2. A method according to claim 1, defined by the intensity patterns being projected onto an object in a measuring cycle with differing intensity patterns and at varying structure distances between adjoining patterns.

3. A method according to claim 2, wherein said projected intensity patterns have a rectangular intensity modulation.

4. A method according to claim 2, wherein said projected intensity patterns are modulated in a sinusoidal shape.

5. A method according to claim 2, wherein said projected intensity patterns are modulated dot-shaped, circular, or elliptical.

6. A method according to claim 2, wherein said projected intensity patterns have a cross-shaped pattern.

7. A method according to claim 2, wherein said projected intensity patterns have a speckled pattern.

8. A method according to claim 2, wherein said the projected intensity patterns have a statistical noise structure.

9. An apparatus for execution of the method according to claim 1, comprising:

a. a projector for projecting defined intensity patterns onto said moving object to create deflected projected patterns corresponding to the shape of said moving object;

b. a camera for recording said deflected projection patterns;

c. a measuring and control computer for receiving a characteristic periodic frequency of said moving object, sending control signals to said projector system to project said defined intensity patterns at regular periods or subperiods of said characteristic periodic frequency;

d. an evaluation protocol software program that accepts the digital data from said recorded deflected projection patterns and determines pre-defined characteristics of said moving object.

10. An apparatus according to claim 9 wherein said pre-defined characteristics comprise the configuration (shape) of said moving object.

11. An apparatus according to claim 9 wherein said pre-defined characteristics comprise the object dimensions of said moving object.

12. An apparatus according to claim 9 wherein said pre-defined characteristics comprise the surface condition of said moving object.

13. An apparatus according to claim 9 wherein said projector is a micro-mirror projector.

14. An apparatus according to claim 9 wherein said projector is a liquid crystal display projector.