Search results for "Laser tracker"
showing 10 items of 10 documents
Robotic geometric and volumetric inspection of high value and large scale aircraft wings
2019
Increased demands in performance and production rates require a radical new approach to the design and manufacturing of aircraft wings. Performance of modern robotic manipulators has enabled research and development of fast automated non-destructive testing (NDT) systems for complex geometries. This paper presents recent outcomes of work aimed at removing the bottleneck due to data acquisition rates, to fully exploit the scanning speed of modern 6-DoF manipulators. The geometric assessment of the parts is carried out with a robotised dynamic laser scanner encoded through an absolute laser tracker. This method allows scanning speeds up to 330mm/s at 1mm pitch. State of the art ultrasonic ins…
Kinematic calibration method for a 5-DOF Gantry-Tau parallel kinematic machine
2013
In this paper a new step-wise approach to kinematic calibration of a 5-DOF Gantry-Tau parallel kinematic machine (PKM) is presented. The approach can be adapted to the modular design of the PKM and the calibration could easily perform part of the assembly instructions for the machine. By using measurements from a laser tracker and least-squares estimates of polynomial functions, a typical accuracy of about 20 micrometer was achieved for the base actuators. The remaining set of 30 general parameters for the hexapod link structure and spherical joint connections were successfully estimated using the Complex search-based evolutionary algorithm.
Optimised assembly mode reconfiguration of the 5-DOF Gantry-Tau using mixed-integer programming
2010
Pulished version of an article in the journal: Meccanica. Also available from the publisher at: http://dx.doi.org/10.1007/s11012-010-9404-y This paper presents a systematic approach based on Mixed Integer Linear Programming for finding an optimal singularity-free reconfiguration path of the 5-DOF Gantry-Tau parallel kinematic machine. The results in the paper demonstrate that singularity-free reconfiguration (change of assembly mode) of the machine is possible, which significantly increases the usable workspace. The method has been applied to a full-scale prototype and the singularity-free path has been verified both in simulations and with physical experiments using real-time control of th…
Off-line path correction of robotic face milling using static tool force and robot stiffness
2015
In this paper the developed method for off-line compensation of tool deflections when milling aluminum with an industrial robot is presented. The efficiency of this approach is verified with high precision measurements of deflections using a laser tracker. The compensation method includes both the static milling process model which can predict the mean value components of the tool forces and a new combined local/global approach for estimating the combined stiffnesses of joints. With a process model such as the one presented in this paper and estimates of the robot's joint stiffness values, the tool path can be adjusted to counteract deflections of the tool during milling operations. The mod…
Using input shaping and pressure feedback to suppress oscillations in slewing motion of lightweight flexible hydraulic crane
2015
This paper presents a method to actively reduce vibrations in the flexible mechanical structure of a hydraulically actuated vehicle loader crane. Based on information on the natural frequency and damping of a simplified model of the crane an input shaping scheme is set up to control the proportional valve leading to substantially reductions in oscillations. The method is compared and combined with a pressure feedback control of the proportional valve that actively suppresses transient variations in pressure. A full scale vehicle loader crane is used in the experimental verification of the method, and the motion of the tool point of the crane is measured by a high precision laser tracker. Th…
Method for estimating combined controller, joint and link stiffnesses of an industrial robot
2014
In this paper a new combined local/global approach for estimating the combined stiffnesses of joints in anthropomorphic robots is presented. The stiffness of each joint is a combination of several effects: i) stiffness of the links, ii) stiffness of joint bearings and gears and iii) stiffness of the position control loops given by the individual axis controller gains in the controller software. Experimental results are presented for an ABB IRB6600 industrial robot using measurements from a FARO Xi laser tracker and an ATI Omega160 force/torque sensor. The results show that there is a significant variation in stiffness among the individual joints of the robot and that the stiffnesses of the …
Real-time 6-DOF Vessel-to-Vessel Motion Compensation using laser tracker
2017
The industry state-of-the-art offshore motion compensation is today carried out by offshore cranes equipped with Active Heave Compensation (AHC) systems, meaning that a hanging load is positioned at a certain height above the seafloor, even though the floating vessel carrying both the crane and the load is moving due to wave disturbances. Lately, there has been an increased interest among the industry also to compensate for the movement of a secondary vessel, which indicates that a more detailed investigation of the Vessel-to-Vessel Motion Compensation (VVMC) problem is required. The primary motivation for such compensation technique is influenced by the demand for load transfer between shi…
Modeling and Analysis of Flexible Bodies Using Lumped Parameter Method
2020
The modeling, identification and analysis of a flexible beam is presented. The lumped parameter method is used to model a flexible beam. The use of camera measurements to identify lumped parameters, namely spring stiffness and damping coefficient, is described. The measurements of the tip oscillations using a high-speed camera and high-precision laser tracker are compared. The static and dynamic behavior of the flexible beam model is compared to the experimental results to show the validity of the model.
Robotic face milling path correction and vibration reduction
2015
In this paper the developed method for off-line compensation of tool deflections and vibration reduction when milling aluminum with an industrial robot is presented. The efficiency of this approach is verified with high precision measurements of deflections using a laser tracker. The compensation method is based on the static milling process model which can predict the mean value components of the tool forces and the passive damping system mounted on the spindle to reduce vibrations. With a process model such as the one presented in this paper and estimates of the robot's joint stiffness values, the tool path can be adjusted to counteract deflections of the tool during milling operations. T…
Calibration of the Norwegian motion laboratory using conformal geometric algebra
2017
This paper applies Conformal Geometric Algebra (CGA) as a tool for calibrating the robotic equipment found in the Norwegian Motion Laboratory. By using the inner product of CGA to measure the distance between a point and the surface of a plane/sphere, the least-squares method can be used to solve for the unknown parameters describing the plane/sphere in an efficient and intuitive way given n measured points. Positional data samples were acquired from using a high precision Laser tracker (FARO Xi), and the overall calibration error was found to be no more than 4.90mm, and the maximum standard deviation 3.25mm. In addition, the applied least-squares algorithm using CGA was twice as fast, when…