An ultraprecision six-axis visual servo-control system

Abstract

This paper presents the development of a novel active visual measurement technique, laterally sampled white-light interferometry (L-SWLI), which is capable of real-time visual tracking of six-degree-of-freedom (6-DOF) rigid body motion with near-nanometer precision. The visual tracking system is integrated with a 6-DOF motion stage to realize an ultraprecision six-axis visual servo-control system. Contrary to conventional interferometric techniques, L-SWLI obtains the complete pose of the target object from a single image frame, therefore allowing real-time tracking. Six-DOF motions are obtained from measuring the fringe pattern on multiple surfaces of the object or from a single surface with additional information gained from conventional image-processing techniques. The feasibility of the visually servoed motion scheme was demonstrated on a micro cantilever. The cantilever was maneuvered in a three-dimensional space with near-nanometer motion resolution in all three translational axes.

A new spatial angle assembly method of the ICF target

“…For the horizontal CCD it may be along the YZ axis to produce the translation deviation and the deviation of rotation around the X direction. Although it is calibrated by adopted Equation (9) in this paper, it is difficult to avoid errors. Tested by using standard hexahedron, the calibration error ∆ Ec α w of the horizontal CCD is 0.06 • and the error ∆ Ec β H of the vertical CCD is 0.07…”

“…In Refs. [7][8][9][10], it was shown that microvision-based precise assembly method is an appropriate solution in the automation of micromanipulation and microassembly tasks. In Refs.…”

Bias-error reduction in nanometer resolution microscopic motion tracking vision systems

“…This mode of bias error has been mentioned intermittently in the literature, 8,9 and is known to occur not only in the case of 2D estimation, but also when the estimation is done for only a single axis. 8 Our derivation of (14)(15)(16) analytically characterizes this error and shows how it depends on the higher order spatial derivatives of the image function. To isolate this primary bias, we let ε ୷ ൌ 0 in (14), and recast to get,…”

“…These systems are utilized for high precision alignment tasks in Semi-conductor fabrication systems, 20,21,23 micro/nano robotic systems employing vision feedback for motion control 14,15 and micro-manipulation of particles. 22 Many of these systems in some way or the other employ sub-pixel image registration algorithms to achieve the required precision.…”

Emulation of Anti-alias Filtering in Vision Based Motion Mmeasurement

“…Sampling is always accompanied by aliasing when the spatial and/or temporal signal content varies in frequencies that exceed the Nyquist frequency [1] . In this paper, we are concerned with temporal aliasing and especially its effect on visual motion tracking [9], [10] . In motion tracking, each temporally sampled image is processed using a variety of algorithms [2]- [4] to estimate A common practice in sampling of a continuous-time signal is to filter the signal before it is passed to the sampler.…”