Expert systems applications

A laser tracking system (LTS) capable of measuring the pose (position and orientation) of a robot moving along arbitrary paths is presented. The measurement principle is based on a modified triangulation. The laser beam is deflected over a cardanic-mounted mirror and follows a retroflector fixed to the robot's end effector. The position of the center of the reflector is calculated from the interferometer distance data, the displacement of the reflected beam with reference to the emitted beam, and the angles of the cardan joint. The edges of the reflector are blackened and create a diffraction pattern within the cross section of the reflected laser beam. By evaluating this pattern using gray-scale image-processing methods, the orientation of the retroreflector can be determined. >

Dynamic measurement of position and orientation of robots

DESIGN NOTE: Improvement on theoretical model for thin-wire and slot measurement by optical diffraction

The customary model, that is, bsin = m, for the measurement of the sizes of slots and thin wires by optical diffraction has been used widely for a long time. In this design note, the model is analysed theoretically and experimentally and improved to the new model, btan = m. Two calibrating slots and thin wires (thin cylinders) are measured by means of optical diffraction. The results show that the new model btan = m is more suitable for describing optical diffraction phenomena and more accurate for measuring a thin wire's diameter.

http://iopscience.iop.org/article/10.1088/0957-0233/10/11/401/pdf

Improvement on theoretical model for thin-wire and slot measurement by optical diffraction

The polarization effect in the measurement of thin wire diameter by laser diffraction has been studied experimentally and theoretically in this paper. The experimental values of a diameter vary sinusoidally with the vibration direction of incident polarized light. The difference between measured diameter values with S and P component of incident light is nearly proportional to the imaginary part of the complex index which represents the optical property of metal wire. Taken into account the phase change of boundary diffraction wave originating from the edges of metal wire, the physical cause of this polarization effect, and its experimental results have been clearly explained.

W. Zheng

Papers

High accuracy microdimension measurement system by using laser and CCD