1,721,131 research outputs found
Time Synchronisation of Low-cost Camera Images with IMU Data based on Similar Motion
No full textClock synchronisation between sensors plays a key role in applications such as in autonomous robot navigation and mobile robot mapping. Such robots are often equipped with cameras for gathering visual information. In this work, we address the problem of synchronizing visual data collected from a low-cost 2D camera, with IMU (Inertial Measurement Unit) data. Both sensors are assumed to be attached to the same rigid body; hence, their motion is correlated. We present a motion based approach using a particle filter to estimate the clock parameters of the camera with the IMU clock as a reference. We apply the Lucas-Kanade optical flow method to calculate the movements of the camera in its horizontal plane corresponding to its recorded images. These movements are correlated to the motion registered by the IMU. This match allows a particle filter to determine the camera clock parameters in the IMU's time frame and are used to calculate the timestamps of the images. We presume that only the IMU sensor provides timestamp data generated from its internal clock. Our experiments show that given enough features are present within the images, this approach has the ability to provide the image timestamps within the IMU's time frame
Localization of hotspots via a lightweight system combining Compton imaging with a 3D lidar camera
No full textEfficient and secure decommissioning of nuclear facilities demands advanced technologies. In this context, gamma-ray detection and imaging are crucial in identifying radioactive hotspots and monitoring radiation levels. Our study is dedicated to developing a gamma-ray detection system tailored for integration into robotic platforms for nuclear decommissioning, offering a safe and automated solution for this intricate task and ensuring the safety of human operators by mitigating radiation exposure and streamlining hotspot localization. Our approach integrates a Compton camera based 3D reconstruction algorithm with a single Timepix3 detector. This eliminates the need for a second detector and significantly reduces system weight and cost. Additionally , combining a 3D camera with the setup enhances hotspot visualization and interpretation, rendering it an ideal solution for practical nuclear decommissioning applications. In a proof-of-concept measurement utilizing a 137Cs source, our system accurately localized and visualized the source in 3D with an angular error of 1 • and estimated the activity with a 3% relative error. This promising result underscores the system's potential for deployment in real-world decommissioning settings. Future endeavors will expand the technology's applications in authentic decommissioning scenarios and optimize its integration with robotic platforms. The outcomes of our study contribute to heightened safety and accuracy for nuclear decommissioning works through the advancement of cost-effective and efficient gamma-ray detection systems.This work was also supported by the Research Foundation - Flanders (FWO) scholarship nr 1SA2621N and 1SA2623N hosted by University Hasselt. The computational resources and services used in this work were provided by the VSC (Flemish Supercomputer Center), funded by the Research Foundation - Flanders (FWO) and the Flemish Government. This research was performed in the context of the Archer project. The Archer project was carried out by academic research partners UHasselt
and KU Leuven in collaboration with the industrial partners EQUANS and Magics Instruments. This project is funded by the Energy Transition Fund of the FOD economy (federal government Belgium). The publication exclusively contains the opinions of the authors. The General Directorate Energy is not liable for any use of the information in the current paper
Pick capacity model for cutting machine tools stored in a next generation Vertical Storage Machine
No full textTools for a group of cutting machine tools in a workshop are often centrally stored, maintained and prepared for use. Using a vertical lift machine (VLM) allows orderly and space-saving storage. It is expected that the total time to prepare tools for delivery in the workshop depends on the chosen VLM architecture and on the strategy for organising the tools in the VLM. This research proposes a mathematical model for determining the total preparation time as a function of the number of items ordered for a series of jobs in the workshop. The model is specific applied for machine cutting tools. While previous research focussed on storage strategies for carrousel storage machines or the basic VLM architecture, this research focusses on five VLM architectures that can be combined with three storage strategies in the mathematical model. The model is largely parametric, allowing for specific numerical values as applicable to the workshop being calculated and allowing to use the technical performance parameters of the VLM. The model illustrates that both the choice of the designated VLM architecture and the choice of storage strategy can have a significant impact on the total time needed to prepare the tools. For both choices to be made, no general rule emerges: a calculation with the specific numerical values for the workshop concerned is appropriate. (C) 2021 The Authors. Published by Elsevier Ltd
Human-robot mobile co-manipulation of flexible objects by fusing wrench and skeleton tracking data
No full textstatus: Publishe
Simulation-driven parameter study of concentric Halbach cylinders for magnetorheological robotic grasping
No full textDue to their peculiar property of controlled stiffness and strength under an external magnetic field, magnetorheological (MR) fluids show great potential in developing hybrid robotic grippers that in the future could offer the same versatility as the human hand. This demands for suffciently strong, compact and switchable magnetic field sources for which permanent magnets are often overshadowed by electromagnets. However, permanent magnets possess higher magnetic flux densities per mass unit, and when assembled in certain ways, they allow to control their joint magnetic field. Within this paper, an extensive parameter study is conducted using grid search for the design of concentric Halbach cylinder assemblies based on finite element simulations. The influence of decisive geometric and material properties on the performance of these magnetic activation mechanisms is studied. These include the magnets’ shapes, sizes and number; the cylinders’ radii and number of pole pairs; and the relative permeabilities of the MR fluid and the grasped object. The performance of a design is measured by a multi-objective function that considers: the mean magnetic flux densities generated in the mechanism’s ON and OFF-state, the magnetic field’s inhomogeneity (i.e. standard deviation) in the ON-state, and the total magnet area for both cylinders. This work concludes by deriving guidelines for the most optimal design of concentric Halbach cylinders for a cylindrical radial bellow gripper.sponsorship: Jeroen Cramer thanks KU Leuven, Diepenbeek Campus for granting a FLOF mandate therewith facilitating this research. Martijn Cramer is a SB PhD fellow at FWO (Research Foundation Flanders) under grant
agreement 1SA6919N. (Fonds Wetenschappelijk Onderzoek|1SA6919N)status: Published onlin
Cartesian Path Planning for Welding Robots: Evaluation of the Descartes Algorithm
No full textMany industrial robot applications require fewer task constraints than the robot’s degrees of freedom. For welding robots, for example, rotations of the welding torch around its axis do not negatively impact welding quality. Furthermore, the tool center point’s Cartesian position and desired orientation as a function of time is often determined by the (manufacturing) process. Nevertheless, programming these robots can be time consuming. Reducing or eliminating this programming cost will allow robots to be used for producing small series. Recently, a promising software package for Cartesian path planning with the name Descartes was released by the ROS-Industrial community. To the authors’ knowledge, an in-depth description of this algorithm and an experimental evaluation is lacking in literature. This paper describes the path planning approach used by the Descartes package. Moreover, the software’s performance is evaluated for several robot welding tasks and the encountered limitations are discussed. In addition, we showed that the planner’s performance can be improved by changing the cost function that the planner’s graph search algorithm minimises.sponsorship: The authors would like to thank the ROS-Industrial consortium and in particular Jorge Nicho for providing us with valuable feedback on this work. The authors also gratefully acknowledge the financial contribution of the KU Leuven Impulse fund IROM. (KU Leuven Impulse fund IROM)status: Publishe
Incorporating Moving Landmarks within 2D Graph-Based SLAM for Dynamic Environments
No full textsponsorship: Peter Aerts is an SB PhD-fellow at FWO (Research Foundation Flanders) under grant agreement 1S67220N. (FWO (Research Foundation Flanders)|1S67220N)status: Publishe
Development of a membrane-shaped MR-based composite draping tool
No full textNowadays, the manufacturing process of composite parts is still dominated by a high level of cost-intensive manual tasks which impedes the use of these materials in composite processing SMEs as well as in high-end automotive and aerospace industries. The draping of fibre sheets is often still carried out manually because of the difficult handling properties, the high variety and complexity of the materials and the product contours. Even the current manipulation tools, for composite draping or preforming in moulds, often lack controllability and flexibility to cope with a high mix of features in the composite product. In automation, these problems are often answered by cost-increasing multi-robotic systems, using multiple degrees of freedom in combination with a large range of feature-specific tools. The need for rather simple, cost-effective manipulation tools triggered the development of a membrane-shaped magnetorheological (MR) based composite draping tool. First, a fluid-filled bag will cover the mould entirely and will perform the initial forming of the composite material whilst both preventing the creation of wrinkles and securing the readily draped areas during further processing. Subsequently, by applying local pressure on the fibre sheet through magnetic activation, draping in narrow or corner-like features will be enhanced. Furthermore, slippage of fibrous material between the membrane and the mould surface can be mastered during forming, facilitating the control of fibre orientation and shear angles. First experimental tests indicate that this technique shows large potential to enable full automation of the entire draping process by the flexible use of a single robot arm and multitool whilst being product and feature independent. C) 2019 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/) Peer-review under responsibility of the scientific committee of the 7th CIRP Global Web Conferenc
Decentral task allocation for industrial AGV-systems with resource constraints
No full textAutomated Guided Vehicles (AGVs) form a large and important part of the logistics transportation systems in today's industry and are widely used, especially in Europe. Today's AGV-systems offered by global manufacturers almost all operate under some form of centralized control where a single central controller coordinates the entire fleet of AGVs. There is a trend towards decentralized control of these systems where AGVs make individual decisions that promote the flexibility, robustness and scalability of transport. However, its practical implementation seems to be in its infancy. In addition to the lack of practical implementation of decentralized control in industrial AGV-systems, we have observed a research gap in intelligent resource management of AGV-systems, which we have tried to address in previous work by proposing a more intelligent resource management approach. In this paper, we have addressed both the perceived lack of practical decentralized AGV control and the lack of intelligent resource management by proposing a decentralized task allocation algorithm based on sequential single-item auctions, taking into account resource constraints, and in which our intelligent resource management approach from previous work is introduced. We have benchmarked our new approach to a genetic algorithm-based task-allocation solver that uses “threshold-100”-charging as a resource management strategy. The result of the proposal is a decentralized task-allocation architecture under resource constraints that could be used in current AGV-systems to add more decentralized features to the fleet.sponsorship: This work is supported by the Mgroup, part of the KU Leuven Campus in Bruges. (Mgroup, part of the KU Leuven Campus in Bruges)status: Published onlin
Decentral task allocation for industrial AGV-systems with routing constraints
No full textsponsorship: This work is supported by the M-group, part of the KU Leuven Campus in Bruges. (M-group, part of the KU Leuven Campus in Bruges)status: Published onlin
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