Measuring and testing – Instrument proving or calibrating – Displacement – motion – distance – or position
Patent
1997-05-05
1998-10-06
Raevis, Robert
Measuring and testing
Instrument proving or calibrating
Displacement, motion, distance, or position
G01B 100
Patent
active
058160965
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a calibration frame for shape measurement systems and in particular to a calibration frame for non-contact optical video camera based shape measurement systems where it is desired to determine the measurement system's physical and geometric properties. Such properties may be used to calibrate the measurement system allowing accurate measurements to be made.
Calibration frames of various forms exist which are viewed by the measurement system which correlates the three-dimensional coordinates of features on the frame with the measurement system's observation of them. These frames are usually precisely constructed objects with features marked on their surface using a contrasting medium. Such features may be a black circle painted on a white surface forming a target or may be of some other pattern which allows the precise location of the target's centre by optical means.
Systems using such frames rely on some degree of interaction with an operator to guide the system's detection of the frame's targets and to enter the three-dimensional coordinates of these targets.
Such systems are prone to operator error causing incorrectly located target centres or causing incorrect three-dimensional coordinates to be entered into the measurement system relating to a particular target. The result of such operator errors is a degradation in the accuracy of the measurement system.
The object of this invention is to provide a calibration frame which overcomes these problems.
The invention may be said to reside in a calibration frame for a non-contact measurement system, including: measurement system; to be identified by the measurement system; the measurement system which relates to the position of that target.
Thus, according to the present invention the measurement system can detect the calibration frame and, in particular, targets activated in the calibration frame by the control means. Information relating to the particular target together with its positional information can then be relayed to the measurement system by the communications link so that the measurement system is provided with the exact positional data relating to the target so that the measurement system receives accurate data to enable calibration of the measurement system.
Preferably the targets comprise light sources.
Preferably the calibration frame includes a rechargeable battery supply for powering the calibration frame to thereby enable the calibration frame to be easily transported and used.
Preferably the calibration frame includes temperature sensing means for sensing the temperature of the environment in which the calibration frame is located and for providing temperature information to thereby provide an indication of any possible expansion or contraction of the frame which would alter the position of the targets with respect to one another.
Preferably the frame structure includes two adjacent sides arranged at an angle with respect to one another and most preferably the sides are formed from aluminium.
Preferably the light sources comprise light emitting diodes.
Preferably the communications link is a bi-directional infrared data link.
Preferably the control system is a microprocessor controller.
Preferably the memory means is an electrically erasable programmable read only memory.
A preferred embodiment of the invention will be described, by way of example, with reference to the accompanying drawings in which:
FIG. 1 is a view of a calibration frame according to the preferred embodiment of the invention;
FIG. 2 is a block diagram of the calibration frame of FIG. 1;
FIG. 3 is a view of a measurement system including the calibration frame of FIGS. 1 and 2;
FIGS. 4, 4A-4F are detailed circuit diagrams of the control system in the calibration frame according to FIGS. 1 and 2; and
FIG. 5 is a circuit detail of the communication link in the preferred embodiment of the invention.
With reference to FIGS. 1 and 2, a calibration frame 10 is shown which comprises a rigid frame structure 12 preferably made from aluminium and in the f
REFERENCES:
patent: 5444481 (1995-08-01), Oshima et al.
patent: 5467634 (1995-11-01), Brady et al.
Ajay Kemal
Ng Kim Chew
Montech Pty, Ltd
Raevis Robert
Southwal Pty, Ltd
LandOfFree
Calibration frame does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Calibration frame, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Calibration frame will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-67992