Laser Doppler Displacement Meter Research Articles

An Investigation of Thermal Behaviour of a Machine Tool on the Dimensional Accuracy of Parts

The thermal behaviour of machine tools can profoundly affect the dimensional accuracy of manufactured parts. Consequently, reducing its influence has become increasingly important to modern manufacturing. One of the most convenient and effective ways to reduce thermal error and enhance working accuracy is volumetric error compensation, especially for CNC machine tools. However, currently available compensation methods are highly complicated and difficult to apply in industry. They require a high‐precision laser interferometer to measure 21 geometric error components and numerous thermocouples to monitor temperature variations. These requirements make such techniques costly and time consuming. This paper describes the development of a simplified and economical method of compensating for thermally induced errors. Compensation is implemented on the basis of only three axial positioning errors, which are assumed to be functions of ball screw nut temperature and travel distance. Instead of an expensive laser interferometer and many thermocouples, a simple laser Doppler displacement meter and only three thermocouples are required for the proposed method. Results show good agreement between measured and predicted thermally induced

Error Detection and Prediction Algorithms: Application in Robotics

This article presents research on error detection and prediction algorithms in robotics. Errors, defined as either agent error or Co-net error, are analyzed and compared. Three new error detection and prediction algorithms (EDPAs) are then developed, and validated by detecting and predicting errors in typical pick and place motions of an Adept Cobra 800 robot. A laser Doppler displacement meter (LDDM?) MCV-500 is used to measure the position of robot gripper in 105 experiment runs. Results show that combined EDPAs are preferred to detect and predict displacement errors in sequential robot motions.

A noncontact laser technique for circular contouring accuracy measurement

The worldwide competition in manufacturing frequently requires the high-speed machine tools to deliver contouring accuracy in the order of a few micrometers, while moving at relatively high feed rates. Traditional test equipment is rather limited in its capability to measure contours of small radius at high speed. Described here is a new noncontact laser measurement technique for the test of circular contouring accuracy. This technique is based on a single-aperture laser Doppler displacement meter with a flat mirror as the target. It is of a noncontact type with the ability to vary the circular path radius continuously at data rates of up to 1000 Hz. Using this instrument, the actual radius, feed rate, velocity, and acceleration profiles can also be determined. The basic theory of operation, the hardware setup, the data collection, the data processing, and the error budget are discussed.

Advanced Bulge Test System

ABSTRACTThe bulge test is an established method of measuring the residual stress and elastic stiffness of thin-film materials. We present an advanced experimental bulge-testing system that provides advantages in speed, accuracy, and flexibility. Key innovations include the use of a Laser Doppler Displacement Meter to measure deflection, an actuated air-cylinder mechanism to vary pressure, and sophisticated computer handling of data acquisition and analysis. A test case demonstrates that repeatability of results is extremely good.

Optical System for Measurement of Pyrotechnic Test Accelerations

This effort was directed at comparing the response of several different accelerometcr and amplifier combinations to the pyrotechnic pulse simulating the ordnance separation of stages of multistage missiles. These pyrotechnic events can contain peak accelerations in excess of 100,000 G and a frequency content exceeding 100,000 Hz. The main thrust of this work was to compare the several accelerometer systems with each other and with a very accurate laser Doppler displacement meter in order to establish the frequency bands and acceleration amplitudes where the accelerometer systems are in error. The comparisons were made in simple sinc-wave and low-acceleration amplitude environments, as well as in very severe pyroshock environments. An optical laser Doppler displacement meter (LDDM) was used to obtain the displacement velocity and acceleration histories, as well as the corresponding shock spectrum.

Laser Doppler Displacement Meter (LDDM)Allows New Diagonal Measurement For LargeAspect Ratio Machine Tool Easily And Accurately

Laser Doppler Displacement Meter (LDDM)Allows New Diagonal Measurement For LargeAspect Ratio Machine Tool Easily And Accurately