MECHATRONIC APPROACH IN PRECISION MEASUREMENTS (original) (raw)
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ABSTRACT The paper deals with the mechatronic means for the accuracy improvement of metal cutting machines, co-ordinate measuring machines, robots, etc. The mechatronic correction means of raster scales, encoders errors and final 3-D position correction of a cutting instrument or touch probe are presented. The technical solutions are given with the application of active materials for smart probes and piezoactuators. A case of calculations for piezoactive raster plates is described together with volumetric control diagrams and the examples of practical implementation.
2016
This paper describes a high-precision optical metrology system - a unique ground test equipment which was designed and implemented for simultaneous precise contactless measurements of 6 degrees-of-freedom (3 translational + 3 rotational) of a space mechanism end-effector [1] in a thermally controlled ISO 5 clean environment. The developed contactless method reconstructs both position and attitude of the specimen from three cross-sections measured by 2D distance sensors [2]. The cleanliness is preserved by the hermetic test chamber filled with high purity nitrogen. The specimen's temperature is controlled by the thermostat [7]. The developed method excludes errors caused by the thermal deformations and manufacturing inaccuracies of the test jig. Tests and simulations show that the measurement accuracy of an object absolute position is of 20 micron in in-plane measurement (XY) and about 50 micron out of plane (Z). The typical absolute attitude is determined with an accuracy better...
ULTRA-HIGH PRECISION POSITIONING VIA A MECHATRONICS APPROACH
Ultra-high precision mechatronics positioning systems are critical devices in current precision engineering and micro- and nano-systems’ technologies, as they allow repeatability and accuracy in the nanometric domain to be achieved. The doctoral thesis deals thoroughly with nonlinear stochastic frictional effects that limit the performances of ultra-high precision devices based on sliding and rolling elements. The state-of-the-art related to the frictional behavior in the pre-sliding and sliding motion regimes is considered and different friction models are validated. Due to its comprehensiveness and simplicity, the generalized Maxwell-slip (GMS) friction model is adopted to characterize frictional disturbances of a translational axis of an actual multi-degrees-of-freedom point-to-point mechatronics positioning system aimed at handling and positioning of microparts. The parameters of the GMS model are identified via innovative experimental set-ups, separately for the actuator-gearhead assembly and for the linear guideways, and included in the overall MATLAB/SIMULINK model of the used device. With the aim of compensating frictional effects, the modeled responses of the system are compared to experimental results when the system is controlled by means of a conventional proportional-integral-derivative (PID) controller, when the PID controller is complemented with an additional feed-forward model-based friction compensator and, finally, when the system is controlled via a self-tuning adaptive regulator. The adaptive regulator, implemented within the real-time field programmable gate array based control system, is proven to be the most efficient and is hence used in the final repetitive point-to-point positioning tests. Nanometric-range precision and accuracy (better than 250 nm), both in the case of short-range (micrometric) and long-range (millimeter) travels, are achieved. Different sensors, actuators and other design components, along with other control typologies, are experimentally validated in ultra-high precision positioning applications as well.
Experimental Static Calibration of an Imu (Inertial Measurement Unit) Based on Mems
2014
Abstract. This work describes the static alignment of a low cost IMU (inertial measurement unit) based on MEMS (Micro Electro-Mechanical System) technology. A precise 3-axis turn table was used to collect measurements from the accelerometers and gyros. For the case of a static alignment, a non-linear Kalman filter was developed to accomplish in real time the estimates of calibration parameters, in order to minimize the navigation errors. The efficiency and performance of the parameters estimation algorithm were shown to be in accordance with the proposition of error reduction. Shown is also the level of precision as well as the time response of the filter to reach accuracy considered satisfactory for this type of sensor.
In this paper, we present a comparison of a double integration using Simpsons's rule and a Kalman filtering in MEMS measurement device output processing for accurate position estimation suitable for the kinematics of an object dragged along a path on the floor. A special purpose experimental setup was designed to allow for an accurate (ground truth) device acceleration and position determination. This is utilized to compute "exact" device output, used as a reference, required to verify Kalman filtering assumptions and to apply different measures of position estimation quality. A Kolmogorov-Smirnov statistical test was applied to test the output noise distribution. To compare the efficiency of the double integrator and the Kalman filtering in the role of position estimation we explored position estimation error, total variance of the output error and the variance of the output error. Means and variances for double integrator and Kalman filtering are listed. Several type...