Open-loop tracking interferometer prototype. "Open-loop" Laser Tracker (3D)
The laser tracker measures 3D position of a retroreflector, attached to machine spindle, based on the multilateraton principle. It enables direct measurement of the volumetric accuracy of a machine tool.
 
 
In "Open-loop" Laser Tracker (2D), we proposed a scheme to perform the same multilateration measurement without using a laser tracker with an automated tracking mechanism -- "open-loop" tracker requires only a laser interferometer mounted on a numerically controlled rotary axis. Here this idea is extended to the 3D measurement.
 
 
We have developed an "open-loop" laser tracker prototype with a laser interferometer mounted on two rotary axes. Experimental demonstration showed that the "error map" of a large-sized machine tool was evaluated with the uncertainty as small as conventional automated laser trackers. (March, 2014)
 
 
>> Publications: JE31, CE56, CJ72, CE51
 
 
 
 
 
 
Open-loop tracking interferometer prototype: Experiment.
 
Open-loop tracking interferometer prototype: Experiment.
 
Figure 1: Experiment with the developed "open-loop" laser tracker prototype. Applied to the volumetric accuracy measurement of a large-sized machine tool. The laser beam is directed to a cat's eye retroreflector attached to machine spindle.
 
 
 
Experimental result; 3D error map.
 
Figure 2: An example "error map" measured by using the "open-loop" laser tracker prototype. An error in measured positions (red circles) from command positions (black dots) is magnified. The machine's actual motion for a cubic command trajectory is evaluated in 3D space.