Volumetric calibration for improving accuracy of AFP/ATL machines

Automated Fiber Placement (AFP) and Automated Tape Laying (ATL) technologies are mostly used in aerospace industry. Deviations from predefined position and orientation of the AFP/ATL machine’s end-effector may cause defects of the final product like gaps and laps of the laminate ply, tow end placement errors, pressure and temperature variations, etc. That makes clear the importance of accuracy of AFP/ATL machines. Calibration is needed to enhance accuracy. Development and implementation of a comprehensive procedure for volumetric calibration of three linear axes is described in this paper. According to ISO 230-1:2012 and ISO 230-2:2014 standards, 18 position dependent and 3 position independent (in total 21) errors of the 3 linear axes are considered. Measurements are performed using laser interferometer on ATL machine produced by company Mikrosam. Obtained data are used for calibration of that machine and validity of the results is verified by comparison with the calibration results obtained by TRAC-CAL software developed by ETALON AG

Avoiding heavy computations in inverse calibration procedure for 7 DOF robot manipulator

Procedure for determining commanded coordinates in machine space if desired coordinates are given is inverse calibration. A large amount of data is considered after measurement procedure and it is essential to locate desired point in the real space which is skewed due to measured geometric errors. The machine workspace is divided to cells using measurement points. It is depicted the importance of finding the proper cell in skewed 3D lat- tice, for calibration of translational axes of ATL machine with large workspace. To calibrate 7 DOF robot manipula- tor, this algorithm is extended. The problem of finding the proper cell in 7D skewed grid needs heavy computations and takes significant amount of computational time. Few ideas for avoiding these computations are described and the influence on the final precision of the calibration procedure is explored

Using Constrained Multi-Optimization in Design of Composite for Filament Wound High Pressure Vessels

Composites as multiphase materials offer the possibility to influence their properties or to add new functionalities by a proper choice and combination of the different phases. In addition to get best properties for the composite design numerous calculations for different combination of the fibers winding angles should be done. This paper targets the design of a composite laminate structure used for production of high pressure vessel. The application developed in this research manages to design a composite with most effective elastic modules, in a time shorter than the usual composite designing time, taking into account filament winding process, materials price as well as the purpose of the final product. This application uses a database of available materials in order to point out which combination creates a pressure vessel of cheaper composite material with the best strength, bulk modulus and load level of failure

Algorithmic approach to geometric solution of generalized Paden–Kahan subproblem and its extension

Kinematics as a science of geometry of motion describes motion by means of position, orientation, and their time derivatives. The focus of this article aims screw theory approach for the solution of inverse kinematics problem. The kinematic elements are mathematically assembled through screw theory by using only the base, tool, and workpiece coordinate systems—opposite to conventional Denavit–Hartenberg approach, where at least n þ 1 coordinate frames are needed for a robot manipulator with n joints. The inverse kinematics solution in Denavit–Hartenberg convention is implicit. Instead, explicit solutions to inverse kinematics using the Paden–Kahan subproblems could be expressed. This article gives step-by-step application of geometric algorithm for the solution of all the cases of Paden–Kahan subproblem 2 and some extension of that subproblem based on subproblem 2. The algorithm described here covers all of the cases that can appear in the generalized subproblem 2 definition, which makes it applicable for multiple movement configurations. The extended subproblem is used to solve inverse kinematics of a manipulator that cannot be solved using only three basic Paden–Kahan subproblems, as they are originally formulated. Instead, here is provided solution for the case of three subsequent rotations, where last two axes are parallel and the first one does not lie in the same plane with neither of the other axes. Since the inverse kinematics problem may have no solution, unique solution, or many solutions, this article gives a thorough discussion about the necessary conditions for the existence and number of solutions. Keywords Screw motion, Paden–Kahan subproblem, geometric algorithm, inverse kinematics, mathematical foundation

Influence Of Each Of The Geometric Errors On The Total Displacement Error Of The Machine

An algorithm for volumetric calibration is developed and verified practically by measuring of all geometric errors after numerical compensation. In this paper, analysis of the contribution of each of 9 translational and 9 rotational position dependent errors and each of 3 position independent errors in total displacement error vector is presented. Changing only one of the errors, and keeping all the others unchanged, the final total error is examined using the simulation based on forward calibration part of the calibration algorithm. The measurement of all 21 volumetric errors is expensive and time consuming. Instead of numerical compensation in the controller, this analysis yields opportunity to enhance accuracy of the machine, measuring and making correction of only few of the geometric errors. Results from the simulation showed that position independent errors have most significant influence on total displacement error. Decreasing of the squareness error S XY improves the mean of norms of total displacement vectors about 25%, and percentage of improvement for squareness error S ZX is about 20%. If all squareness errors are reduced by factor 0.04, then total improvement is more than 51%

Computer-based simulation and validation of robot accuracy improvement method and its verification in robot calibration procedure

Algorithm for improving accuracy of six-axes robot is developed and validation method based on computer simulation is implemented. Optimization is used to minimize the distances between nominal and actual positions of the tool. That way, the parameters of the robot are calibrated and using such calibrated parameters, accuracy of the robot is significantly enhanced. Measurement is done using API Radian laser tracker and experimental data is collected on KUKA 480 R3330. For the set of 75 points used for calibration, simulation predicted reduction of the mean of the total displacement error from 1.619 mm to 0.174 mm. After that, the same points were used for verification procedure. Another measurement is performed, using the calibrated parameters and numerically calculated compensation of the machine coordinates of the robot. The mean of total displacement error was 0.293 mm and that way the correctness of described method is verified

Calculation of carbon footprinting – making the invisible visible

Climate change is recognized as a serious global environmental problem with serious consequences for our social and economic infrastructure. The greenhouse gas (GHG) emissions that cause climate change are emitted mainly from burning fossil fuels. In order to affect climate change, GHG emissions must be measured and reduced. A new term “carbon footprint” has been coined, to describe the quantity of CO2 and other greenhouse gas (GHG) emissions emitted directly and indirectly by any individuals, companies, events, products or services. There is a number of standard methodologies for calculating carbon footprint. The basic calculation of carbon footprinting is a quick exercise, but in some other cases, when the organization calculates some indirect emissions or the emissions from particular product, a software for that purpose is available. Calculating a carbon footprint is a useful exercise only as a part of a complete environmental management system