Method and system for point by point measurement of spatial coordinates

• US 5,440,392 A
• Filed: 04/11/1994
• Issued: 08/08/1995
• Est. Priority Date: 10/11/1991
• Status: Expired due to Term

• Current Assignee: Metronor AS
• Original Assignee: Metronor AS
• Inventors: Rotvold, Oyvind, Pettersen, Alf
• Primary Examiner(s): Evans, F. L.
• Application Number:
  US08/211,734
• Time in Patent Office: 484 Days
• Field of Search: 356/375, 356/376, 33/502, 33/503, 33/504, 33/554, 33/555, 33/556
• US Class Current: 356/620
• CPC Class Codes: G01B 11/00 Measuring arrangements characterised by the use of optical techniques
• CPC Class Codes: G01B 11/002 for measuring two or more coordinates
• CPC Class Codes: G01C 15/00 Surveying instruments or accessories not provided for in groups G01C1/00 - G01C13/00
• CPC Class Codes: G01S 5/16 using electromagnetic waves other than radio waves

Abstract

A system for point by point measurement of spatial coordinates, in which a touch probe including three point-sized light sources at known local coordinates relative to a local probe fixed coordinate system and with a touch point at known location relative to the local coordinate system, is used such that the touch probe touches the point to be measured. A single opto-electronic angle sensor for measurement of spatial direction towards point sized light sources is set up such that its field of view/work area covers the essential parts of the object to be measured, and such that the light sources of the touch probe are seen from the angle sensor for all the relevant measurement points. The spatial directions for all of the light sources of the touch probe are registered simultaneously. Based on the registered spatial directions, the position and orientation of the touch probe are calculated relative to said single angle sensor, and such that the position of the touch probe is related to its point of contact with the measured object.

Claims

1. A method for point-by-point measurement of spatial coordinates of each of a plurality of points on an object, comprising:

(a) positioning a single opto-electronic angle sensor designed to measure spatial direction to each of a plurality of point-sized light sources, such that its field of view or working area generally covers said object;

(b) successively touching to each of said points a touch point of a touch probe having at least three point-sized light sources respectively disposed at known coordinates relative to a local probe coordinate system and a touch point disposed at a known location relative to said local probe coordinate system, while maintaining visibility of said touch probe to said angle sensor at each such touching;

(c) simultaneously sensing, using said angle sensor, at each said touching, a spatial direction for each of said light sources and registering said spatial directions; and

(d) computing the position and orientation of said touch probe relative to said angle sensor at each said touching, from the spatial directions registered in step (c).

2. The method of claim 1, further comprising:

(e) repeating step (b) and (c) a plurality of instances in regard to each of a plurality of said points on said object, with said angle sensor repositioned, in accordance with step (a), for each such instance; and

in conducting step (d) combining the respective spatial directions by a least squares analysis or bundle adjustment calculation, for improving accuracy of said position and orientation as calculated in step (d).

3. The method of claim 1, wherein:

the touch probe used in step (b) has at least three point-sized light sources, three of which are disposed in a first plane, and two others of which are disposed in a second plane which is spaced from said first plane.

4. The method of claim 1, wherein:

said computing of step (d) is conducted by a computer;

said touch probe is arranged to be controlled by said computer; and

steps (b) and (c), further include operating said computer to vary illumination time and intensity of said light sources.

5. A system for point-by-point measurement of spatial coordinates of each of a plurality of points on an object, comprising:

(a) a single opto-electronic angle sensor to measure spatial direction to each of a plurality of point-size light sources, and to be positioned such that its field of view or working area generally covers said object;

(b) a touch probe having at least three point-sized light sources respectively disposed at known coordinates relative to a local probe coordinate system and a touch point disposed at a known location relative to said local probe coordinate system, for successively touching each of said points while maintaining visibility of said touch probe to said angle sensor at each such touching;

said angle sensor being operable for simultaneously sensing at each said touching, a spatial direction for each of said light sources;

(c) a register for registering said spatial directions as sensed by said angle sensor; and

(d) a computer for computing the position and orientation of said touch probe relative to said angle sensor at each said touching, from the spatial directions registered in said register.

6. The system of claim 5, further comprising:

control means effectively connecting said computer with said touch probe for varying illumination time and intensity of said light sources while using said angle sensor to measure said spatial directions.

7. The system of claim 5, wherein:

said light sources have a predetermined spectral distribution; and

said angle sensor has an optical filter which matches said predetermined spectral distribution.