Effect of Variation of Link Lengths and Stiffness on the Gearing Ratio of a Four Bar Mechanism With Application to Aircraft Trim Tabs

2015 ◽  
Author(s):  
Abey Dessalegn ◽  
Yimesker Yihun ◽  
Joao Paulo Flores Fernandes ◽  
Hamid M. Lankarani
Keyword(s):  
Rigid Body ◽  
Closed Form ◽  
Real Life ◽  
Algebraic Solution ◽  
End Effector ◽  
Mechanical Advantage ◽  
Kinematic Chains ◽  
Joint Clearances

Kinematic chains or mechanisms have conventionally been analyzed comprising of links that behave as rigid members and links assumed to be built at nominal sizes. Such mechanisms, articulating entirely from rigid-body translations and/or rotations and nominally established links may not closely represent the actual real life manufactured parts with tolerances and joint clearances. It is important to identify the allowable variations in the linkages especially when the end-effector of the mechanism generates a path or a function and/or a tightly controlled gearing ratio or mechanical advantage is required. In this study, the band of solutions that can be obtained from the variation in lengths of linkages and the effect of stiffness is generated to better understand the quality of the mechanism performance. The application of four bar mechanism in an aileron trim tab system that utilizes a rotatory actuator to move the tab surface is used to demonstrate the band of solutions. Then CATIA V5 is used to layout the geometry and design the linkages within the prescribed airfoil. The MSC Adams is used to calculate the initial gearing ratio and for validation of values. A Matlab®code is developed and used to analyze the effects of the variation of lengths and stiffness of linkages on the tab speed using closed form algebraic solution. Finally, a comparison is made to illustrate and quantify the effects of link lengths and stiffness on the gearing ratio/mechanical advantage of the system.

Forward Problem Singularities of Manipulators Which Become PS-2RS or 2PS-RS Structures When the Actuators Are Locked

2003 ◽  
Author(s):  
Raffaele Di Gregorio
Keyword(s):  
Rigid Body ◽  
Parallel Manipulator ◽  
Parallel Manipulators ◽  
Geometric Interpretation ◽  
Forward Problem ◽  
End Effector ◽  
Kinematic Chains ◽  
Position And Orientation ◽  
Manipulator Design

The instantaneous forward problem (IFP) singularities of a parallel manipulator (PM) must be determined during the manipulator design and avoided during the manipulator operation, because they are configurations where the end-effector pose (position and orientation) cannot be controlled by acting on the actuators any longer, and the internal loads of some links become infinite. When the actuators are locked, PMs become structures consisting of one rigid body (platform) connected to another rigid body (base) by means of a number of kinematic chains (limbs). The geometries (singular geometries) of these structures where the platform can perform infinitesimal motion correspond to the IFP singularities of the PMs the structures derive from. This paper studies the singular geometries both of the PS-2RS structure and of the 2PS-RS structure. In particular, the singularity conditions of the two structures will be determined. Moreover, the geometric interpretation of their singularity conditions will be provided. Finally, the use of the obtained results in the design of parallel manipulators which become either PS-2RS or 2PS-RS structures, when the actuators are locked, will be illustrated.

Dynamic Modelling and Analysis of General Linked Mechanisms With Compliance

1987 ◽  
Author(s):  
L. Shih ◽  
A. A. Frank
Keyword(s):  
Equations Of Motion ◽  
Real Life ◽  
Dynamic Modelling ◽  
Joint Models ◽  
Kinematic Chains ◽  
3 Dimensional ◽  
Compliant Joint ◽  
Joint Reaction Forces ◽  
Reaction Forces ◽  
Joint Clearances

Abstract This paper presents a simple and systematic method of analysis for the kinematics and dynamics of spatial multi-loop mechanisms with closed and open kinematic chains. The Newton-Euler formulation is used to derive the dynamic equations of motion of each link. This formulation completely eliminates kinematic redundancies and singularities. Compliant joint models are introduced to cover real life effects such as joint clearances, lubrication of joints, joint to link compliances, etc. Direct computation of joint reaction forces results. An example of the application of the method to the dynamic and kinematic analysis of a 3 dimensional spatial slider-crank mechanism with a flywheel is presented.

Properties of the SX-YS-ZS Structures and Singularity Determination in Parallel Manipulators Which Generate Those Structures

2004 ◽  
Author(s):  
Raffaele Di Gregorio
Keyword(s):  
Rigid Body ◽  
Parallel Manipulator ◽  
Parallel Manipulators ◽  
Geometric Interpretation ◽  
Forward Problem ◽  
Unified Approach ◽  
End Effector ◽  
Kinematic Chains ◽  
Position And Orientation ◽  
Manipulator Design

The instantaneous forward problem (IFP) singularities of a parallel manipulator (PM) must be determined during the manipulator design and avoided during the manipulator operation, because they are configurations where the end-effector pose (position and orientation) cannot be controlled by acting on the actuators any longer, and the internal loads of some links become infinite. When the actuators are locked, PMs become structures consisting of one rigid body (platform) connected to another rigid body (base) by means of a number of kinematic chains (legs). The geometries (singular geometries) of these structures where the platform can perform infinitesimal motion correspond to the IFP singularities of the PMs the structures derive from. In this paper, the singular geometries of the structures with topology SX-YS-ZS (S stands for spherical pair, whereas X, Y and Z stand for three generic one-dof pair which may be or may not be of the same type) are studied with a unified approach. The presented approach leads to obtain an analytic condition which allows all the singular geometries of these structures to be determined. Moreover, the geometric interpretation of the found singularity condition and the exhaustive enumeration of the types of singular geometries is provided. Finally, the use of the presented results in the design of the manipulators which become one structure with topology SX-YS-ZS when the actuators are locked is discussed.

Forward Problem Singularities of Manipulators Which Become PS-2RS or 2PS-RS Structures When the Actuators are Locked

2004 ◽  
Vol 126 (4) ◽  
pp. 640-645 ◽  
Author(s):  
Raffaele Di Gregorio
Keyword(s):  
Rigid Body ◽  
Parallel Manipulators ◽  
Geometric Interpretation ◽  
Forward Problem ◽  
End Effector ◽  
Kinematic Chains ◽  
Geometric Conditions ◽  
New Form ◽  
Position And Orientation ◽  
Manipulator Design

The instantaneous forward problem (IFP) singularities of a parallel manipulator (PM) must be determined during the manipulator design and avoided during the manipulator operation, because they are configurations where the end-effector pose (position and orientation) cannot be controlled by acting on the actuators any longer, and the internal loads of some links become infinite. When the actuators are locked, PMs become structures consisting of one rigid body (platform) connected to another rigid body (base) by means of a number of kinematic chains (limbs). The geometries (singular geometries) of these structures where the platform can perform infinitesimal motion correspond to the IFP singularities of the PMs the structures derive from. This paper studies the singular geometries both of the PS-2RS structure and of the 2PS-RS structure. In particular, the singularity conditions of the two structures will be written in a new form. This new form will directly bring to a new geometric interpretation of their singularity conditions and to the exhaustive enumeration of the geometric conditions identifying their singular geometries. Such an enumeration will reveal that some geometric conditions were not identified in the literature. Finally, the use of the obtained results in the design of parallel manipulators which become either PS-2RS or 2PS-RS structures, when the actuators are locked, will be illustrated.

Qualitative assessment of equipment failure cause finding and removal

2018 ◽  
pp. 116-126
Author(s):  
E. A. Vakulin ◽  
A. I. Zayats ◽  
V. A. Beklemeshev ◽  
V. A. Ivashkevich ◽  
V. A. Khazhiev ◽  
...  
Keyword(s):  
Production Condition ◽  
Real Life ◽  
Open Pit Mine ◽  
Qualitative Assessment ◽  
Open Pit ◽  
Quality Level ◽  
Equipment Failure ◽  
Operation Conditions ◽  
Failure Investigation

Investigation of failures is one of the critical activities of mining and haulage equipment operability assurance in mining. Maintaining failure investigation at the required quality level, it is possible to identify provisions, rules and procedures that should be revised or changed, operation conditions that should be improved, additional personnel training, if required, etc. Investigation of failures in mines is under responsibility of machine men and electricians of maintenance and operation services. In reality, factory management and setup for production condition weak concernment of these workers in quality investigation aimed at finding of sources of equipment failures. This article describes real-life results achieved in development and use of maintenance service operation, technology and management monitoring. The requirements are substantiated for quality improvement in failure cause finding and removal in mining and haulage equipment at Chernogorsky open pit mine, SUEK-Khakassia. Causes of the present quality of failure investigation by machine men of Chernogorsky Repair and Engineering Works and Chernogorsky open pit mine are revealed. The proposed recommended practices will improve quality of mining and haulage equipment failure investigation.

The Relationship between the Development of Human Capital and the Agricultural Economy in Rural Areas

2020 ◽  
pp. 61-65
Author(s):  
B.A. Voronin ◽  
◽  
I.P. Chupina ◽  
Ya.V. Voronina ◽  
◽  
...  
Keyword(s):  
Human Capital ◽  
Rural Areas ◽  
Agricultural Production ◽  
Agricultural Sector ◽  
Real Life ◽  
Standard View ◽  
Household Factors ◽  
Economic Transformations ◽  
The Relationship

The article discusses a non-standard view of the formation of human capital for work in organizations of the agricultural sector of the economy, in the context of modern socio-economic transformations. In the classical sense, human capital for agriculture should be formed and developed in rural areas. But in real life, this is not always the case, because there are many factors that prevent the classical solution of this problem. First, the demographic factor affects, second, social and household factors, and third, in many rural areas there are no working agricultural organizations where qualified agricultural specialists can work. All these and other circumstances actualize the problem of the quality of human capital in rural areas in relation to the development of agricultural production.

Automated Insulin Delivery Systems: Today, Tomorrow and User Requirements

2021 ◽  
pp. 193229682110299
Author(s):  
Marga Giménez ◽  
Ignacio Conget ◽  
Nick Oliver
Keyword(s):  
Lived Experience ◽  
Diabetes Management ◽  
Real Life ◽  
Insulin Delivery ◽  
Qualitative Assessment ◽  
Management Tool ◽  
Diabetes Distress ◽  
Glycemic Targets

Automated insulin delivery (AID) is the most recent advance in type 1 diabetes (T1D) management. It has the potential to achieve glycemic targets without disabling hypoglycemia, to improve quality of life and reduce diabetes distress and burden associated with self-management. Several AID systems are currently licensed for use by people with T1D in Europe, United States, and the rest of the world. Despite AID becoming a reality in routine clinical practice over the last few years, the commercially hybrid AID and other systems, are still far from a fully optimized automated diabetes management tool. Implementation of AID systems requires education and support of healthcare professionals taking care of people with T1D, as well as users and their families. There is much to do to increase usability, portability, convenience and to reduce the burden associated with the use of the systems. Co-design, involvement of people with lived experience of T1D and robust qualitative assessment is critical to improving the real-world use of AID systems, especially for those who may have greater need. In addition to this, information regarding the psychosocial impact of the use of AID systems in real life is needed. The first commercially available AID systems are not the end of the development journey but are the first step in learning how to optimally automate insulin delivery in a way that is equitably accessible and effective for people living with T1D.

scholarly journals The contribution of the Italian residents in neurology to the COVID-19 crisis: admirable generosity but neurological training remains their priority

2021 ◽  
Author(s):  
Cristina Tassorelli ◽  
Vincenzo Silani ◽  
Alessandro Padovani ◽  
Paolo Barone ◽  
Paolo Calabresi ◽  
...  
Keyword(s):  
Clinical Training ◽  
Real Life ◽  
Healthcare Management ◽  
Point Of View ◽  
Research Activity ◽  
High Quality ◽  
Research Activities ◽  
Italian Regions ◽  
Training And Research

Abstract Background The coronavirus disease 2019 (COVID-19) pandemic has severely impacted the Italian healthcare system, underscoring a dramatic shortage of specialized doctors in many disciplines. The situation affected the activity of the residents in neurology, who were also offered the possibility of being formally hired before their training completion. Aims (1) To showcase examples of clinical and research activity of residents in neurology during the COVID-19 pandemic in Italy and (2) to illustrate the point of view of Italian residents in neurology about the possibility of being hired before the completion of their residency program. Results Real-life reports from several areas in Lombardia—one of the Italian regions more affected by COVID-19—show that residents in neurology gave an outstanding demonstration of generosity, collaboration, reliability, and adaptation to the changing environment, while continuing their clinical training and research activities. A very small minority of the residents participated in the dedicated selections for being hired before completion of their training program. The large majority of them prioritized their training over the option of earlier employment. Conclusions Italian residents in neurology generously contributed to the healthcare management of the COVID-19 pandemic in many ways, while remaining determined to pursue their training. Neurology is a rapidly evolving clinical field due to continuous diagnostic and therapeutic progress. Stakeholders need to listen to the strong message conveyed by our residents in neurology and endeavor to provide them with the most adequate training, to ensure high quality of care and excellence in research in the future.

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