Comparison of force-fiels parametrizations as applied to conformational analysis of ribofuranosides

International audienc

Usage of I++ Simulator to Program Coordinate Measuring Machines when Common Programming Methods are difficult to apply

Nowadays, simulators facilitate tasks performed daily by the engineers of different branches, including coordinate metrologists. Sometimes it is difficult or almost impossible to program a Coordinate Measuring Machine (CMM) using standard methods. This happens, for example, during measurements of nano elements or in cases when measurements are performed on high-precision (accurate) measuring machines which work in strictly air-conditioned spaces and the presence of the operator in such room during the programming of CMM could cause an increase in temperature, which in turn could make it necessary to wait some time until conditions stabilize. This article describes functioning of a simulator and its usage during Coordinate Measuring Machine programming in the latter situation. Article also describes a general process of programming CMMs which ensures the correct machine performance after starting the program on a real machine. As an example proving the presented considerations, measurement of exemplary workpiece, which was performed on the machine working in the strictly air-conditioned room, was describe

Determination of influence of the parameters connected with the stabilization of the position on the 5-axis manipulators’ operation accuracy

The 5-axis systems, especially those that use in their kinematic chain both prismatic joints and revolute kinematic pairs are gaining popularity in many scientific disciplines with manufacturing, metrology and robotics at the forefront. This is therefore important to undertake research aiming in identification of sources of inaccuracies in their functioning and investigation on possibility of eliminating or compensating them. A significant impact on 5-axis kinematic structures accuracy may be assigned to parameters associated with the stabilization of the machine position and angular position, such as position stabilization time, position overshoot and drift of positioning accuracy. These parameters are well described in ISO 9283 standard related to performance criteria and test methods for industrial robots. The methodology presented in this standard is adapted for testing the impact of mentioned parameters for functioning of 5-axis kinematic structures other than industrial robots, which mainly include five-axis coordinate measuring systems and machine tools. A series of experiments performed on five-axis coordinate measuring system is presented in this paper, their results are assessed in a quantitative manner and basing on them a general algorithm for assessing the significance of impact of position stabilization parameters on functioning of the manipulator is proposed

Method for predicting the accuracy of rotational elements measurements using the five-axis coordinate measuring system

The measurements of solids of revolution are one of the most common task in industrial practice. Therefore it is not surprising, that new solutions dedicated to improve accuracy and acceleration of measurements of rotational components are emerging. In this group, the new generation of articulating probing systems (with ability of continuous indexation) is worth mentioning. These probing devices combined with standard CMM forms the five-axis coordinate system. Such solution results in measurements acceleration and also improve measurement repeatability. Studies on this type of probing systems proved that their accuracy depends strongly on the angular orientation of probing system used during measurement. Therefore authors developed model that allows simulation of probing system errors for any orientation. This article describes an attempt to use the model to find the configuration of the probing system that would provide the highest accuracy for rotational elements measurements. The simulation results are compared to the real measurements of standard elements performed on five axis measuring system. Described prediction method could have a beneficial effect on improving the accuracy of measurements and, as a result, on reducing production costs by minimizing the risk of erroneous decision on the conformity of products with their geometric specifications

The crystal and molecular structure of a diglycosylamine: the N-analogue of peracetylated α,β-trehalose

International audienc

A conformational study of the xyloglucan oligomer, XXXG, by NMR spectroscopy and molecular modeling

International audienc