scholarly journals A Novel Flexible Virtual Fixtures for Teleoperation

2014 ◽  
Vol 2014 ◽  
pp. 1-10
Author(s):  
Guanglong Du ◽  
Ping Zhang
Keyword(s):  
Collision Detection ◽  
Performance Comparison ◽  
Control Mode ◽  
Spatial Constraints ◽  
Motion Constraints ◽  
Virtual Fixtures ◽  
Machine Interface ◽  
Manipulation Task ◽  
Performance Results ◽  
Constrained Robot

This paper proposed a novel spatial-motion-constraints virtual fixtures (VFs) method for the human-machine interface collaborative technique. In our method, two 3D flexible VFs have been presented: warning pipe and safe pipe. And a potential-collision-detection method based on two flexible VFs has been proposed. The safe pipe constructs the safe workspace dynamically for the robot, which makes it possible to detect the potential collision between the robot and the obstacles. By calculating the speed and the acceleration of the robot end-effecter (EE), the warning pipe can adjust its radius to detect the deviation from the EE to the reference path. These spatial constraints serve as constraint conditions for constrained robot control. The approach enables multiobstacle manipulation task of telerobot in precise interactive teleoperation environment. We illustrate our approach on a teleoperative manipulation task and analyze the performance results. The performance-comparison experimental results demonstrate that the control mode employing our method can assist the operator more precisely in teleoperative tasks. Due to the properties such as collision avoidance and safety, operators can complete the tasks more efficiently along with reduction in operating tension.

Spatial Motion Constraints Using Flexible Virtual Fixtures

2013 ◽  
Vol 427-429 ◽  
pp. 24-28
Author(s):  
Xiao Min Lu ◽  
Ping Zhang ◽  
Guang Long Du
Keyword(s):  
Collision Detection ◽  
Detection Method ◽  
Control Mode ◽  
Spatial Motion ◽  
Motion Constraints ◽  
Reference Path ◽  
Virtual Fixtures ◽  
Manipulation Task

To improve the performance of the multi-obstacle manipulation task of the telerobot in the precise interactive teleoperation environment, this paper proposes a novel spatial-motion-constraints virtual fixtures (VFs) method with two 3D flexible VFs, the warning pipe and the safe pipe, as well as a potential-collision-detection method based on these two flexible VFs. The safe pipe constructs the safe workspace dynamically for the robot while the warning one can detect the deviation from the EE to the reference path by adjusting the radius. Experiments show that the control mode employing our method can assist the operator more precisely in teleoperative tasks along with the reduction in the operating tension.

Simulation Comparison of PEMFC Micro-Cogeneration Units With Conventional and Innovative Fuel Processing

2010 ◽  
Author(s):  
Leonardo Roses ◽  
Davide Bonalumi ◽  
Stefano Campanari ◽  
Paolo Iora ◽  
Giampaolo Manzolini
Keyword(s):  
Polymer Electrolyte Membrane ◽  
Performance Comparison ◽  
Fuel Processing ◽  
Electrolyte Membrane ◽  
Simulated Performance ◽  
Commercial Code ◽  
The One ◽  
Definition Of ◽  
Performance Results ◽  
Energy Balances

This paper deals with the performance comparison over simulated micro-cogeneration units based on polymer electrolyte membrane fuel cells (PEMFC or PEM), when the fuel is processed by means of two contrasting techniques. On the one hand with the use of conventional natural gas steam reforming (SR), and on the other, the adoption of an innovative palladium based membrane-reformer. After the definition of the plant layout, which reflects the results of previous studies and includes all the components of a 4 kW PEM for combined heat and power production, the comparison among the plant performances is carried out with two approaches: (i) using a in-house developed code (GS), able to calculate mass and energy balances, as well as a number of specific component parameters, already applied to a large variety of plant simulations, and (ii) using a commercial code (Aspen Plus®). The comparison allows to validate the simulated performance results as well as to evidence the advantages of the two approaches and to assess the effects of different simulation assumptions.

Time-Optimal Control of Two Robots Holding the Same Workpiece

1993 ◽  
Vol 115 (3) ◽  
pp. 441-446 ◽  
Author(s):  
J. E. Bobrow ◽  
J. M. McCarthy ◽  
V. K. Chu
Keyword(s):  
Optimal Control ◽  
Contact Force ◽  
Degrees Of Freedom ◽  
Unique Feature ◽  
Robot Arm ◽  
Robot System ◽  
Motion Constraints ◽  
Time Optimal ◽  
Internal Forces ◽  
Constrained Robot

An algorithm is given which minimizes the time for two robots holding the same workpiece to move along a given path. The unique feature of these systems is that they have more actuators than degrees of freedom. The method can be applied to any constrained robot system, including the case where one robot arm moves in contact with a surface. In addition to finding the optimum torque histories, the algorithm determines the optimum contact force between the each robot and the workpiece throughout the motion. Constraints on these internal forces are easily introduced into the algorithm.

A Numerical and Experimental Performance Comparison of an 86 MM Radial and Back Swept Turbine

2009 ◽  
Author(s):  
Liam Barr ◽  
Stephen Spence ◽  
David Thornhill ◽  
Paul Eynon
Keyword(s):  
Numerical Models ◽  
Performance Comparison ◽  
Point Of View ◽  
Blade Angle ◽  
Experimental Performance ◽  
Numerical Predictions ◽  
Radial Turbine ◽  
Optimum Velocity ◽  
Performance Results ◽  
Performance Gains

This report details the numerical and experimental investigation of the performance characteristics of a conventional radial turbine compared with a new back swept design for the same application. The blade geometry of an existing turbine from a turbocharger was used as a baseline. A new back swept blade was subsequently designed for the rotor, which departed from the conventional radial inlet blade angle to incorporate a 25° inlet blade angle. A comparative numerical analysis between the two geometries is presented. Results show that the 25° back swept blade offers significant increases in efficiency while operating at lower than optimum velocity ratios (U/C). Improvements in efficiency at off-design conditions could significantly improve turbocharger performance since the turbine typically experiences lower than optimum velocity ratios while accelerating during engine transients. A commercial CFD code was used to construct single passage steady state numerical models. The numerical predictions show off-design performance gains of 2% can be achieved, while maintaining design point efficiency. A finite element stress analysis was conducted to show that the nonradial inlet blade angle could be implemented without exceeding the acceptable stress levels for the rotor. A modal analysis was also carried out in order to identify the natural blade frequencies, showing that these were not significantly changed by the implementation of backswept blading. A prototype backswept rotor was produced and tested in a direct comparison with the baseline rotor geometry. Experimental performance results showed strong correlations with those obtained numerically, and verified the predicted performance gains at off-deign velocity ratios. This numerical and experimental study has shown that it is feasible from both an aerodynamic and structural point of view to improve the performance characteristic of a radial turbine at lower than optimum velocity ratios through the implementation of back swept blading.

Design and Evaluation of Human–Machine Interface for NEXUS: A Custom Microassembly System

2020 ◽  
Vol 8 (4) ◽  
Author(s):  
Danming Wei ◽  
Mariah B. Hall ◽  
Andriy Sherehiy ◽  
Dan O. Popa
Keyword(s):  
Visual Servoing ◽  
Degrees Of Freedom ◽  
Three Dimensional ◽  
Human Machine Interface ◽  
Mems Technology ◽  
Machine Interface ◽  
Micro Electromechanical System ◽  
Performance Results ◽  
Assembly Performance ◽  
Assembly Rate

Abstract Microassembly systems utilizing precision robotics have long been used for realizing three-dimensional microstructures such as microsystems and microrobots. Prior to assembly, microscale components are fabricated using micro-electromechanical-system (MEMS) technology. The microassembly system then directs a microgripper through a series of automated or human-controlled pick-and-place operations. In this paper, we describe a novel custom microassembly system, named NEXUS, that can be used to prototype MEMS microrobots. The NEXUS integrates multi-degrees-of-freedom (DOF) precision positioners, microscope computer vision, and microscale process tools such as a microgripper and vacuum tip. A semi-autonomous human–machine interface (HMI) was programmed to allow the operator to interact with the microassembly system. The NEXUS human–machine interface includes multiple functions, such as positioning, target detection, visual servoing, and inspection. The microassembly system's HMI was used by operators to assemble various three-dimensional microrobots such as the Solarpede, a novel light-powered stick-and-slip mobile microcrawler. Experimental results are reported in this paper to evaluate the system's semi-autonomous capabilities in terms of assembly rate and yield and compare them to purely teleoperated assembly performance. Results show that the semi-automated capabilities of the microassembly system's HMI offer a more consistent assembly rate of microrobot components and are less reliant on the operator's experience and skill.

scholarly journals Sector Portfolio Performance Comparison between Islamic and Conventional Stock Markets

2019 ◽  
Vol 11 (17) ◽  
pp. 4618
Author(s):  
María de la O González ◽  
Francisco Jareño ◽  
Camalea El Haddouti
Keyword(s):  
Financial Crisis ◽  
Interest Rates ◽  
Performance Measures ◽  
Stock Markets ◽  
Global Financial Crisis ◽  
Negative Impact ◽  
Performance Comparison ◽  
Portfolio Performance ◽  
Sample Period ◽  
Performance Results

This study compares the performance of sector portfolios from Islamic and conventional stock markets, using standard as well as current performance measures for a recent sample period between January 1996 and December 2015. Furthermore, to test the robustness of our analysis and to determine which type of portfolios offer better performance depending on the economic cycle, the full sample period is divided into three sub-sample periods: Before, during and after the recent global financial crisis. The three main outcomes of this research confirm that, first, the sector with the best performance results is Health Care, while the sector with the worst performance results is Financials for the Islamic as well as the conventional stock market. Second, the post-crisis sub-period exhibits the best performance not only in conventional but also in Islamic markets, confirming that portfolio performance depends on the economic stage and highlighting emerging signs of economic recovery. Third, Islamic sector portfolios, as a whole, show better performance than conventional sector portfolios for all performance measures—not just for the full period but also for the three sub-sample periods. The superior risk-adjusted returns of the Islamic sector portfolios, even during the recent global financial crisis, can be justified, among other reasons, by the moderated uncertainty and speculation, as well as the fact that Islamic finance prevents interest rates that have a negative impact on the economy. Thus, Sharia-compliant assets can contribute to improving the sustainability of unattractive performance portfolios during financial crises.

scholarly journals Scene Classification for Sports Video Summarization Using Transfer Learning

Sensors ◽  
2020 ◽  
Vol 20 (6) ◽  
pp. 1702 ◽  
Author(s):  
Muhammad Rafiq ◽  
Ghazala Rafiq ◽  
Rockson Agyeman ◽  
Gyu Sang Choi ◽  
Seong-Il Jin
Keyword(s):  
Data Augmentation ◽  
Video Summarization ◽  
Performance Comparison ◽  
Practical Implementation ◽  
Scene Classification ◽  
Advertising Agencies ◽  
Sports Video ◽  
Performance Results ◽  
Implementation Gaps

This paper proposes a novel method for sports video scene classification with the particular intention of video summarization. Creating and publishing a shorter version of the video is more interesting than a full version due to instant entertainment. Generating shorter summaries of the videos is a tedious task that requires significant labor hours and unnecessary machine occupation. Due to the growing demand for video summarization in marketing, advertising agencies, awareness videos, documentaries, and other interest groups, researchers are continuously proposing automation frameworks and novel schemes. Since the scene classification is a fundamental component of video summarization and video analysis, the quality of scene classification is particularly important. This article focuses on various practical implementation gaps over the existing techniques and presents a method to achieve high-quality of scene classification. We consider cricket as a case study and classify five scene categories, i.e., batting, bowling, boundary, crowd and close-up. We employ our model using pre-trained AlexNet Convolutional Neural Network (CNN) for scene classification. The proposed method employs new, fully connected layers in an encoder fashion. We employ data augmentation to achieve a high accuracy of 99.26% over a smaller dataset. We conduct a performance comparison against baseline approaches to prove the superiority of the method as well as state-of-the-art models. We evaluate our performance results on cricket videos and compare various deep-learning models, i.e., Inception V3, Visual Geometry Group (VGGNet16, VGGNet19), Residual Network (ResNet50), and AlexNet. Our experiments demonstrate that our method with AlexNet CNN produces better results than existing proposals.

Design of Double Twister’s New Control System Based on Multi-Electromotor Driving

2012 ◽  
Vol 236-237 ◽  
pp. 588-592
Author(s):  
Ming Lai Lv ◽  
Yan Hong Yuan ◽  
Jian Yi Zhang
Keyword(s):  
Control System ◽  
Control Mode ◽  
Step Motor ◽  
Servo Motor ◽  
Embedded Control ◽  
Work Requirements ◽  
Working Principle ◽  
Machine Interface ◽  
User Friendly ◽  
Hardware Circuit

This paper discussed the working principle of the twister and the overall framework,designed an embedded control system of the multi-electromotor drive new twister which as the core of the ARM. Research the control mode of the ACMotor,Step Motor and Servo Motor,and design of hardware circuit to realize the coordination between them，which can make the twister meet the work requirements in the process.Design user-friendly man-machine interface to simplify the process.The experimental results show that the control system can satisfy the new twisting machine realization,also have a good real-time,and can meet the demand for the accuracy of the process.

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