Complete, Minimal and Continuous Kinematic Error Models of Perfect Multi-DOF Joints for Parallel Manipulators

Kinematic error model plays an important role in improving the positioning accuracy of robot manipulators by kinematic calibration. In order to get a better calibration result, the error model should satisfy complete, minimal and continuous criteria. In order to meet the complete requirement, the multi degree-of-freedom (DOF) joints, such as universal or spherical joint in parallel robots, have to be regarded as serial chains formed by multiple independent single DOF joints, such that the manufacturing errors of these joints can be considered. However, several previous work found that these manufacturing errors for some parallel manipulators have little effect on the accuracy improvement. Besides, considering these kind of errors will cause the kinematics to be much more complicated. Therefore, under the assumptions of perfectly manufactured universal, spherical and cylinder joints, a complete, minimal and continuous (CMC) error model is presented in this paper. The identifiability of the kinematic errors of these multi-DOF joints are analytically analyzed. In order to verify the correctness and effectiveness of the proposed method, a numerical simulation of kinematic calibration is conducted on a 6-UPS parallel manipulator. The calibration result is also compared to the one derived from the error model with 138 error parameters. Since the error model and calibration methods are described uniformly, it can be applied to most parallel manipulators.

Calibration of Digital Thermometer using Sensor and Indicator Method

A Calibration has been done for digital thermometer using a sensor and indicator method. The unit under test manufactured by Fluke with 54-II type and serial number 13160058, meanwhile, the standards that used are PT100 sensor from Omega and an indicator from Additel. The calibration result from 12 setpoints shows the average correction value as 0.61 ºC with uncertainty as 0.32 ºC and K factor as 2.0 at 95% confidence level

FRUIT SWEETNESS CHARACTERIZATION USING IMPEDANCE SPECTROSCOPY METHOD

This paper presents fruit sweetness characterization using impedance spectroscopy method. Agricultural product processing requires technology implementation to increase its production. The fruit sweetness component is composed of a mixture of fructose, glucose, and sucrose. The measurements of these molecules are usually done with a four-point probe and use DC (direct current). In this study, a fruit sweetness characterization using impedance spectroscopy method has been developed, which uses an AC (alternating current). By using this method, the fruit sweetness level can be characterized based on the impedance measurement on the flesh of fruit. The obtained characterization results show the fruit sweetness level; it can be measured by the impedance measurement. This method could characterize the fruit sweetness well and agrees with the calibration result.

УСОВЕРШЕСТВЕННАЯ МЕТОДИКА ДЛЯ ИЗМЕРЕНИЯ ПРЯМОЙ НОРМАЛЬНОЙ СОЛНЕЧНОЙ РАДИАЦИИ

In the article the new method for calibration of pyrheliometers on direct normal solar radiation is suggested. The proposed method provides for non-dependence of the calibration result on optical thickness of pure atmosphere integrated on whole spectrum, which makes it possible to increase the accuracy of measurements.

Calibration of torque measurement under constant rotation in a wind turbine test bench

To determine the efficiency of multi-MW wind turbines, the torque measurement in wind turbine test benches has to be performed with an accuracy better than 0.2 %. To this end, the torque measurement has to be traced to national standards in the MN m range. This can be done by using a novel torque transfer standard in combination with a newly developed torque calibration procedure under constant rotation, which are both presented and discussed in this paper. The calibration procedure was performed on a 4 MW wind turbine test bench and the evaluation of the calibration result, including a measurement uncertainty, is explained in detail.

DISEMINASI RESISTOR STANDAR 1 KΩ KE STANDAR KERJA

<p>Abstrak<br />Diseminasi nilai kalibrasi resistor standar kepada standar kerja di Puslit Metrologi - LIPI telah dilakukan. Hal ini bertujuan untuk mendapatkan hasil kalibrasi dan estimasi ketidakpastiannya yang valid dan tertelusur ke SI pada standar kerja. Desiminasi dilakukan dengan cara mengimplenmentasikan nilai kalibrasi resistor standar 1 kΩ ke resistor acuan dan kemudian ke standar kerja. Nilai yang telah diturunkan kepada standar kerja, reference multimeter, telah dibandingkan dengan nilai pengukuran yang dilakukan oleh KRISS (Korea Research Institute of Standards and Science) melalui kriteria derajat ekuivalensi. Error number berdasarkan kriteria derajat ekuivalensi antara Metrologi - LIPI dan KRISS pada resistor-resistor 100Ω, 10Ω, dan 1Ω masing-masing adalah sebesar 0,51, 0,73, dan 0,87. Berdasarkan error number tersebut, hasil pengukuran Metrologi - LIPI memiliki kesesuaian nilai ukur dengan hasil ukur KRISS. Lebih daripada itu, hal tersebut telah memvalidasi hasil kalibrasi dan estimasi ketidakpastian dari resistor acuan dan standar kerja di Puslit Metrologi - LIPI.<br />Kata kunci: nilai kalibrasi, resistor standar, standar kerja, kriteria derajat kebebasan, validasi.</p><p><br />Abstract<br />Dissemination of calibration value of standard resistor to working standard in Research Center for Metrology LIPI has been done. It aims to get the calibration result and the uncertainty estimation that are valid and traceable to SI on the working standard. The desimination was performed by implementing calibration value of 1 kΩ standard resistor to reference resistor and then to working standard. The value that had been disseminated to working standard, reference multimeter, had been compared to the measurement value made by KRISS (Korea Research Institute of Standards and Science) through a degree of equivalence criteria. The error numbers based on the degree of equivalence criteria between Metrology-LIPI and KRISS for the resistors measurement of 100Ω, 10Ω, and 1Ω were 0.51, 0.73, and 0.87 respectively. Based on those error numbers, Metrology-LIPI measurement results had the measuring value agreement with KRISS measurement results. Moreover, Its had validated calibration result and the uncertainty estimation of reference resistor and working standard in Metrology LIPI<br />Keywords: calibration value, standard resistor, working standard, degree of equivalence criteria, validation.</p>