scholarly journals Dynamic Behavior Analysis for a Six Axis Industrial Machining Robot

2011 ◽  
Vol 423 ◽  
pp. 65-76 ◽  
Author(s):  
Claudiu Bisu ◽  
Mehdi Cherif ◽  
Alain Gerard ◽  
Jean Yves K'nevez
Keyword(s):  
Dynamical Behavior ◽  
Calibration Procedure ◽  
Second Phase ◽  
Measurement Device ◽  
Fiber Placement ◽  
Serial Robots ◽  
Machining Robot ◽  
Serial Robot ◽  
New Applications ◽  
The University

The six axis robots are widely used in automotive industry for their good repeatability (as defined in the ISO92983) (painting, welding, mastic deposition, handling etc.). In the aerospace industry, robot starts to be used for complex applications such as drilling, riveting, fiber placement, NDT, etc. Given the positioning performance of serial robots, precision applications require usually external measurement device with complexes calibration procedure in order to reach the precision needed. New applications in the machining field of composite material (aerospace, naval, or wind turbine for example) intend to use off line programming of serial robot without the use of calibration or external measurement device. For those applications, the position, orientation and path trajectory precision of the tool center point of the robot are needed to generate the machining operation. This article presents the different conditions that currently limit the development of robots in robotic machining applications. We analyze the dynamical behavior of a robot KUKA KR240-2 (located at the University of Bordeaux 1) equipped with a HSM Spindle (42000 rpm, 18kW). This analysis is done in three stages. The first step is determining the self-excited frequencies of the robot structure for three different configurations of work. The second phase aims to analyze the dynamical vibration of the structure as the spindle is activated without cutting. The third stage consists of vibration analysis during a milling operation.

scholarly journals A Nelder–Mead algorithm-based inverse transient analysis for leak detection and sizing in a single pipe

2021 ◽  
Author(s):  
Oussama Choura ◽  
Caterina Capponi ◽  
Silvia Meniconi ◽  
Sami Elaoud ◽  
Bruno Brunone
Keyword(s):  
Transient Analysis ◽  
Experimental Tests ◽  
Leak Detection ◽  
Calibration Procedure ◽  
Second Phase ◽  
Viscoelastic Parameters ◽  
The Difference ◽  
Single Pipe ◽  
The University ◽  
Nelder Mead Algorithm

Abstract In this paper the results of an experimental validation of a technique for leak detection in polymeric pipes based on the inverse transient analysis (ITA) are presented. In the proposed ITA the Nelder–Mead algorithm is used as a calibration tool. Experimental tests have been carried out in an intact and leaky high-density polyethylene (HDPE) single pipe installed at the Water Engineering Laboratory (WEL) of the University of Perugia, Italy. Transients have been generated by the fast and complete closure of a valve placed at the downstream end section of the pipe. In the first phase of the calibration procedure, the proposed algorithm has been used to estimate both the viscoelastic parameters of a generalized Kelvin–Voigt model and the unsteady-state friction coefficient, by minimizing the difference between the numerical and experimental results. In the second phase of the procedure, the calibrated model allowed the evaluation of leak size and location with an acceptable accuracy. Precisely, in terms of leak location the relative error was smaller than 5%.

Force Capabilities of Two-Degree-of-Freedom Serial Robots Equipped With Passive Isotropic Force Limiters

2015 ◽  
Author(s):  
Meiying Zhang ◽  
Thierry Laliberté ◽  
Clément Gosselin
Keyword(s):  
Human Robot Interaction ◽  
Contact Forces ◽  
Degree Of Freedom ◽  
Practical Implementation ◽  
Robot Interaction ◽  
End Effector ◽  
Serial Robots ◽  
Serial Robot ◽  
Maximum Contact ◽  
Two Degree Of Freedom

This paper proposes the use of passive force and torque limiting devices to bound the maximum forces that can be applied at the end-effector or along the links of a robot, thereby ensuring the safety of human-robot interaction. Planar isotropic force limiting modules are proposed and used to analyze the force capabilities of a two-degree-of-freedom planar serial robot. The force capabilities at the end-effector are first analyzed. It is shown that, using isotropic force limiting modules, the performance to safety index remains excellent for all configurations of the robot. The maximum contact forces along the links of the robot are then analyzed. Force and torque limiters are distributed along the structure of the robot in order to ensure that the forces applied at any point of contact along the links are bounded. A power analysis is then presented in order to support the results. Finally, examples of mechanical designs of force/torque limiters are shown to illustrate a possible practical implementation of the concept.

IMPROVED TOW-END DETECTION FOR FIBER PLACEMENT INSPECTION USING MACHINE LEARNING

2021 ◽  
Author(s):  
ADRIANA W. (AGNES) BLOM-SCHIEBER ◽  
WEI GUO ◽  
EKTA SAMANI ◽  
ASHIS BANERJEE
Keyword(s):  
Machine Learning ◽  
Learning Algorithm ◽  
Image Data ◽  
Detection Algorithm ◽  
Automated Inspection ◽  
Machine Learning Algorithm ◽  
Fiber Placement ◽  
Inspection Systems ◽  
Automated Fiber Placement ◽  
The University

A machine learning approach to improve the detection of tow ends for automated inspection of fiber-placed composites is presented. Automated inspection systems for automated fiber placement processes have been introduced to reduce the time it takes to inspect plies after they are laid down. The existing system uses image data from ply boundaries and a contrast-based algorithm to locate the tow ends in these images. This system fails to recognize approximately 10% of the tow ends, which are then presented to the operator for manual review, taking up precious time in the production process. An improved tow end detection algorithm based on machine learning is developed through a research project with the Boeing Advanced Research Center (BARC) at the University of Washington. This presentation shows the preprocessing, neural network and post‐processing steps implemented in the algorithm, and the results achieved with the machine learning algorithm. The machine learning algorithm resulted in a 90% reduction in the number of undetected tows compared to the existing system.

On Force and Motion Control of Serial-Parallel Robots

1996 ◽  
Author(s):  
Shih-Liang Wang
Keyword(s):  
Control Algorithm ◽  
Virtual Work ◽  
Parallel Robot ◽  
Parallel Robots ◽  
Joint Torque ◽  
Compact Structure ◽  
Serial Robots ◽  
S Matrix ◽  
Serial Robot ◽  
Rate Control Algorithm

Abstract A serial-parallel robot has the high stiffness and accuracy of a parallel robot, and a large workspace and compact structure of a serial robot. In this paper, the resolved force control algorithm is derived for serial-parallel robots, including a 3-articulated-arm platform robot, a linkage robot, and two cooperating serial robots. A S matrix is derived to relate joint torque to the external load. Using the principle of virtual work, S is used in resolved rate control algorithm to relate the tool velocity to joint rate. S can be easily expanded to the control of redundant actuation, and it can be used to interpret singularity. MATLAB is used to verify these control algorithms with graphical motion animation.

How to measure the radial load of radial lip seals

2021 ◽  
Vol 68 (3-4) ◽  
pp. 5-12
Author(s):  
Simon Feldmeth ◽  
Mario Stoll ◽  
Frank Bauer
Keyword(s):  
Practice Guideline ◽  
Best Practice ◽  
Parameter Study ◽  
Radial Load ◽  
Measurement Device ◽  
Lip Seal ◽  
Study Results ◽  
Lip Seals ◽  
German Standard ◽  
The University

The radial load of a radial lip seal indicates how strongly the sealing lip is pressed on the shaft. The radial load significantly affects the function of the seal. The German standard DIN 3761-9 describes the measurement of the radial load according to the split-shaft method but leaves room for interpretation. During the revision of the standard, a parameter study was conducted at the University of Stuttgart. This study analyses the influence of the measurement device, the mandrels and the measuring procedure on the results. Based on the study results, recommendations are derived and summarized in a best-practice guideline, which should enable an appropriate and reproducible measurement of the radial load.

Reliability-Based Analysis and Optimization of the Gravity Balancing Performance of Spring-Articulated Serial Robots with Uncertainties

2021 ◽  
pp. 1-32
Author(s):  
Vu Linh Nguyen ◽  
Chin-Hsing Kuo ◽  
Po Ting Lin
Keyword(s):  
Pso Algorithm ◽  
Reliability Based Design Optimization ◽  
Swarm Optimization ◽  
Reliability Based Design ◽  
Serial Robots ◽  
Simulation Based ◽  
Serial Robot ◽  
Simulation Results ◽  
Uncertainty Level

Abstract This article proposes a method for analyzing the gravity balancing reliability of spring-articulated serial robots with uncertainties. Gravity balancing reliability is defined as the probability that the torque reduction ratio (the ratio of the balanced torque to the unbalanced torque) is less than a specified threshold. The reliability analysis is performed by exploiting a Monte Carlo simulation (MCS) with consideration of the uncertainties in the link dimensions, masses, and compliance parameters. The gravity balancing begins with a simulation-based analysis of the gravitational torques of a typical serial robot. Based on the simulation results, a gravity balancing design for the robot using mechanical springs is realized. A reliability-based design optimization (RBDO) method is also developed to seek a reliable and robust design for maximized balancing performance under a prescribed uncertainty level. The RBDO is formulated with consideration of a probabilistic reliability constraint and solved by using a particle swarm optimization (PSO) algorithm. A numerical example is provided to illustrate the gravity balancing performance and reliability of a robot with uncertainties. A sensitivity analysis of the balancing design is also performed. Lastly, the effectiveness of the RBDO method is demonstrated through a case study in which the balancing performance and reliability of a robot with uncertainties are improved with the proposed method.

scholarly journals Designing and Implementing of An Online Library Managment System

2017 ◽  
Vol 5 (3) ◽  
pp. 278
Author(s):  
Maiwan B. Abdulrazaq ◽  
Omar M. Mustafa
Keyword(s):  
Second Phase ◽  
Short Message ◽  
University Campus ◽  
Library Management ◽  
Library Management System ◽  
System Usability Scale ◽  
Message Service ◽  
Two Phases ◽  
Online Library ◽  
The University

One of the most important fields in education is library. The library is a fast-growing system. The traditional methods of maintaining it are no longer dynamic and efficient. For expeditious retrieval and dissemination of information and better service for the clientele, an application of modern techniques has become absolutely indispensable. A properly computerized library will help its users with quick and prompt services. Therefore, this Paper produces an efficient Online Library Management System (OLMS) for university campus. The main purpose of this Paper is to design and implement the (OLMS). The OLMS consists of two modules: External Pages Module and Internal Pages Module. The first module is with limited operation such as (viewing, searching and registration request). The second module for the personal account can do the operations like (storing, searching, viewing, borrowing, downloading and etc.). The system controllers are two types. The first one is the (Co_Admin) which can manage library operation. The second one is the administrator which can create and manage university libraries and also can create (Co_Admin) for each faculty library. The system can generate different types of reports and can also calculate the (fines) on the users, also any request or response will be done by E-Mail and short message service (SMS). The OLMS was designed and implemented by using (MySQL, HTML, CSS, PHP, JavaScript, JQuery, Ajax and Bootstrap) techniques. The system was tested in two phases: the first phase identifies the views and preferences of users with the specification of the system outputs, depending on the requirements of the proposed system. The second phase measures the abilities of the system through System Usability Scale (SUS) technique with the contribution of 26 potential users of the system and the recorded rate 76% as overall satisfaction of OLMS implementation. A reasonable degree of compatibility and harmony between the university and the system requirements of application has been found in the University of Zakho.

Ragnar Rommetveit: A full life

2020 ◽  
Vol 26 (3) ◽  
pp. 528-539
Author(s):  
Bente Eriksen Hagtvet ◽  
Per Linell ◽  
James V Wertsch ◽  
Astri Heen Wold
Keyword(s):  
Social Cognitive ◽  
Human Cognition ◽  
Second Phase ◽  
Cognitive Approach ◽  
Social Sciences And Humanities ◽  
Message Structure ◽  
1960S And 1970S ◽  
The 1960S ◽  
University Of Oslo ◽  
The University

Over a long professional lifetime, Ragnar Rommetveit contributed to numerous disciplines in the social sciences and humanities, reflecting discussions in global social science and his own unending quest to understand social and individual life. His remarkable career and impact can be outlined in terms of four main phases. The first involved general social psychology in the 1950s and was reflected in Social Norms and Roles (1953/1955). In the second phase during the 1960s and 1970s, he focused on language-related psycholinguistic research leading to publications such as his 1968 volume Words, Meanings and Messages. The third phase came in the 1970s and 1980s and was motivated by his critique of formal linguistics and resulted in his short, magisterial 1974 volume On Message Structure. The fourth phase between 1980 and 2010 focused on “dialogism,” giving rise to works such as his 1992 article “Outlines of a dialogically based social-cognitive approach to human cognition and communication.” Along with his intellectual accomplishments, Rommetveit’s brilliance and generosity inspired students and colleagues at the University of Oslo, as well as from around the world. His capacity to engage with others in unending mediations on communication and mental life ranks among his most important legacies.

The JOBS Program: Impact on Job Seeker Motivation, Reemployment, and Mental Health

2014 ◽  
Author(s):  
Richard H. Price ◽  
Amiram D. Vinokur
Keyword(s):  
Mental Health ◽  
Job Search ◽  
Large Scale ◽  
Best Practice ◽  
Social Research ◽  
University Of Michigan ◽  
Job Seekers ◽  
Jobs Program ◽  
New Applications ◽  
The University

JOBS is a research-based program delivered in a group format and designed to aid unemployed job seekers in their search for employment. The program has demonstrated positive impacts on job-search skills, motivation, reemployment rates, and mental health. The JOBS program was designed and tested in large-scale randomized trials at the Institute for Social Research at the University of Michigan. The positive effect of JOBS has been replicated in a number of national and international settings. Research, theory, and principles for best practice in the implementation of JOBS are discussed, as well as future directions for research and new applications.

scholarly journals LAYING THE GROUNDWORK FOR BECOMING AN AGE-FRIENDLY UNIVERSITY: A MULTI-PHASE STUDY

2019 ◽  
Vol 3 (Supplement_1) ◽  
pp. S78-S79
Author(s):  
Melissa L Cannon ◽  
Renata Kerwood ◽  
Mandie Kondash ◽  
Samuel Rowley ◽  
Hannah Wehr
Keyword(s):  
Older Adults ◽  
Data Collection ◽  
Lifelong Learning ◽  
Second Phase ◽  
Senior Center ◽  
University Campus ◽  
Research Participants ◽  
Phase Study ◽  
Multi Phase ◽  
The University

Abstract As evidenced by the growing Age-Friendly University (AFU) global network, institutions of higher education are increasingly seeking ways to enhance the experiences of older adults who use them for reasons such as lifelong learning, career development, and intergenerational engagement. This multi-phase study explored the barriers and facilitators for older adults accessing a public university in a small Oregon town. The first phase of the study involved survey data collection from 46 members of the local senior center adjacent to the university campus. For the second phase, researchers recruited a sample from the survey respondents and used snowball sampling to conduct 12 interviews with senior center members, past and current senior center directors, and key contacts among university staff. The third phase of data collection paired student researchers with older adult research participants (N=14) in participatory action research to capture the unique perspectives of the research participants visiting the university campus using photovoice and a follow-up focus group. Quantitative data were analyzed using SPSS while qualitative data were analyzed using team coding and intensive group discussion to develop categories and themes. Findings revealed various opportunities to increase age-friendliness according to the principles outlined by the AFU initiative, such as developing a lifelong learning center on campus, strengthening the university-senior center partnership, and removing accessibility barriers in order to make the university campus friendlier for people of all ages and abilities. These findings are being used in a proposal to join the AFU network and to shape the university’s AFU vision.

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