Dynamic Performance Limitations Due to Yielding in Cable-Driven Robotic Manipulators

2005 ◽  
Vol 128 (1) ◽  
pp. 311-318 ◽  
Author(s):  
Xiaolei Yin ◽  
Alan P. Bowling
Keyword(s):  
Degrees Of Freedom ◽  
Dynamic Performance ◽  
Robotic Manipulators ◽  
Comprehensive Description ◽  
Body Model ◽  
Kinematic Coupling ◽  
Rigid Body Model ◽  
Torque Capacity ◽  
Reaction Forces ◽  
Performance Limitations

This paper presents a method for characterizing the performance limitations imposed by the yielding of the cables in systems with cable-driven transmissions. The method involves developing a rigid-body model of the system, where the cable tensions are considered as reaction forces. The kinematic coupling between links in the mechanism due to the use of cables is also considered. Here, the limitations on dynamic performance caused by cable yielding are added to the limitations caused by the bounds on actuator torque capacity, in order to give a more comprehensive description of the system’s capabilities. A two degrees-of-freedom planar mechanism is analyzed in order to illustrate the methodology.

scholarly journals Wind Influence on Miro-launcher Dynamics Model

2019 ◽  
Vol 304 ◽  
pp. 07014
Author(s):  
Teodor-Viorel Chelaru ◽  
Valentin Pana ◽  
Alexandru Iulian Onel ◽  
Tudorel-Petronel Afilipoae ◽  
Andrei Filip Cojocaru ◽  
...  
Keyword(s):  
Atmospheric Turbulence ◽  
Correlation Functions ◽  
Degrees Of Freedom ◽  
Dynamics Model ◽  
Six Degrees Of Freedom ◽  
Body Model ◽  
Rigid Body Model ◽  
Wind Influence ◽  
Three Stages ◽  
Flight Parameters

The paper presents aspects regarding wind influence in dynamics of the three stages micro-launcher. The work is focus on atmospheric turbulence, with dedicated linear model based on characteristics correlation functions, that can be attached to the rigid body model with six degrees of freedom. The results analyzed will be the flight parameters of the launcher, with the wind influence. The novelty of the paper consists in dedicated wind models developed and their implementation in six degrees of freedom micro-launcher model.

Classification of Compliant Mechanisms and Determination of the Degrees of Freedom Using the Concepts of Compliance Number and Pseudo-Rigid-Body Model

2019 ◽  
Author(s):  
Pratheek Bagivalu Prasanna ◽  
Ashok Midha ◽  
Sushrut G. Bapat
Keyword(s):  
Rigid Body ◽  
Degrees Of Freedom ◽  
Compliant Mechanisms ◽  
Compliant Mechanism ◽  
Body Model ◽  
Active Compliance ◽  
Kinematic Behavior ◽  
Rigid Body Model

Abstract Understanding the kinematic properties of a compliant mechanism has always proved to be a challenge. A concept of compliance number offered earlier emphasized the development of terminology that aided in its determination. A method to evaluate the elastic degrees of freedom associated with the flexible segments/links of a compliant mechanism using the pseudo-rigid-body model (PRBM) concept is provided. In this process, two distinct classes of compliant mechanisms are developed involving: (i) Active Compliance and (ii) Passive Compliance. Furthermore, these also aid in a better characterization of the kinematic behavior of a compliant mechanism. A more lucid interpretation of the significance of compliance number is provided. Applications of this method to both active and passive compliant mechanisms are exemplified. Finally, an experimental procedure that aids in visualizing the degrees of freedom as calculated is presented.

scholarly journals Flexible Model for Miro-launcher Dynamics

2019 ◽  
Vol 304 ◽  
pp. 07013
Author(s):  
Teodor-Viorel Chelaru ◽  
Valentin Pana ◽  
Alexandru Iulian Onel ◽  
Tudorel-Petronel Afilipoae ◽  
Andrei Filip Cojocaru ◽  
...  
Keyword(s):  
Rigid Body ◽  
Degrees Of Freedom ◽  
Elastic Model ◽  
Six Degrees Of Freedom ◽  
Body Model ◽  
Rigid Body Model ◽  
Three Stages ◽  
Flight Parameters ◽  
Elastic Modes ◽  
Flexible Model

The paper presents aspects regarding flexible model used for describing the dynamics of the three stages micro-launcher. This work analyses transverse flexible oscillations. By the hypotheses adopted, the flexibility problem will be reduced to a group of equations that will be attached to the rigid body model with six degrees of freedom, thus obtaining an elastic model for the launcher. The results analysed will be the flight parameters the launcher, with the influence of the elastic modes considered. The novelty of the paper consists in highlighting the influence of elasticity on the launcher control problem.

A Methodology for Determining Static Mode Shapes of a Compliant Mechanism Using the Pseudo-Rigid-Body Model (PRBM) Concept and the Degrees-of-Freedom Analysis

2019 ◽  
Author(s):  
Sushrut G. Bapat ◽  
Pratheek Bagivalu Prasanna ◽  
Ashok Midha
Keyword(s):  
Rigid Body ◽  
Degrees Of Freedom ◽  
Compliant Mechanisms ◽  
Compliant Mechanism ◽  
Mode Shapes ◽  
Model Concept ◽  
Static Mode ◽  
Displacement Boundary ◽  
Body Model ◽  
Rigid Body Model

Abstract Traditionally, the deflected configuration of compliant segments is determined through rigorous mathematical analysis using Newtonian mechanics. Application of these principles in evaluating the deformed configuration of compliant mechanisms, containing a variety of segment types, becomes cumbersome. This paper introduces a methodology to determine the expected deflected configuration(s) of a compliant mechanism, for a given set of load and/or displacement boundary conditions. The method utilizes the principle of minimum total potential energy, in conjunction with the degrees-of-freedom analysis and the pseudo-rigid-body model concept. The static mode shape(s) of compliant segments are integrated in identifying the possible functional configuration(s) of a given compliant mechanism’s structural configuration. The methodology, in turn, also facilitates the in situ determination of the deformed configuration of the constituent compliant segments. It thus assists in the identification of an appropriate pseudo-rigid-body model for design and analysis of a compliant mechanism.

Joint reactions in rigid or flexible body mechanisms with redundant constraints

2012 ◽  
Vol 60 (3) ◽  
pp. 617-626 ◽  
Author(s):  
M. Wojtyra ◽  
J. Frączek
Keyword(s):  
Rigid Body ◽  
Degrees Of Freedom ◽  
Flexible Body ◽  
Flexible Bodies ◽  
Redundant Constraints ◽  
Constraint Equations ◽  
Body Model ◽  
Rigid Body Model ◽  
Flexible Models

Abstract The problem of joint reactions indeterminacy, in engineering simulations of rigid body mechanisms is most often caused by redundant constraints which are defined as constraints that can be removed without changing the kinematics of the system. In order to find a unique set of all joint reactions in an overconstrained system, it is necessary to reject the assumption that all bodies are rigid. Flexible bodies introduce additional degrees of freedom to the mechanism, which usually makes the constraint equations independent. Quite often only selected bodies are modelled as the flexible ones, whereas the other remain rigid. In this contribution it is shown that taking into account flexibility of selected mechanism bodies does not guarantee that unique joint reactions can be found. Problems typical for redundant constraints existence are encountered in partially flexible models, which are not overconstrained. A case study of a redundantly constrained spatial mechanism is presented. Different approaches to the mechanism modelling, ranging from a purely rigid body model to a fully flexible one, are investigated and the obtained results are compared and discussed.

Compliant Floating-Opposing-Arm (FOA) Centrifugal Clutch

2004 ◽  
Vol 126 (1) ◽  
pp. 169-177 ◽  
Author(s):  
Nathan B. Crane ◽  
Larry L. Howell ◽  
Brent L. Weight ◽  
Spencer P. Magleby
Keyword(s):  
Experimental Data ◽  
Compliant Mechanism ◽  
Significant Cost ◽  
Body Model ◽  
Cost Reductions ◽  
Rigid Body Model ◽  
Torque Capacity ◽  
Contact Surfaces ◽  
High Torque ◽  
Assembly Analysis

This paper introduces the floating-opposing-arm (FOA) centrifugal clutch, presents a mathematical model for its analysis, and demonstrates the validity of a model to predict clutch performance with experimental data. The novelty of the clutch includes an arrangement of aggressive and non-aggressive contact surfaces in connected pairs to achieve a high torque carrying capability while maintaining starting smoothness and stability. As a compliant mechanism, it has fewer parts than traditional centrifugal clutches, and has the potential for significant cost reductions in manufacturing and assembly. Analysis of the FOA clutch is made difficult by the combination of dynamics and elastic deformation required for its operation. A model, based on the pseudo-rigid-body model, simplifies the engagement speed and torque capacity analyses. The model is validated by testing individual clutches and by demonstrating clutch designs in typical applications.

Research on the Workpiece Kinematics in Face Lapping with Friction Drive

2012 ◽  
Vol 565 ◽  
pp. 318-323 ◽  
Author(s):  
Uwe Heisel ◽  
Philipp Jakob
Keyword(s):  
Material Removal ◽  
Motion Tracking ◽  
Removal Rate ◽  
Motion Patterns ◽  
Body Model ◽  
Precise Knowledge ◽  
Rigid Body Model ◽  
Reaction Forces ◽  
Multi Body

In face lapping, the achievable material removal rate and surface quality depend strongly on the workpiece kinematics. Hence, the precise knowledge of the kinematics is an important requirement for increasing the efficiency and quality of the superfinishing process. The main focus of experiment is to identify how different workpiece geometries influence the resulting kinematics. The process kinematics in face lapping with friction drive is performed by means of motion tracking. Multi-body simulation allows extending the understanding of the process. Apart from the motion patterns of the lapping process, which were determined before, experimentally established reaction forces are used for verifying the considered rigid body model. A deviation of less than 10 % between the forces determined experimentally and by simulation verifies that it is a promising possibility to assess the kinematics by simulation.

A Methodology for Determining Static Mode Shapes of a Compliant Mechanism Using the Pseudo-Rigid-Body Model Concept and the Degrees-Of-Freedom Analysis

2020 ◽  
Vol 12 (2) ◽  
Author(s):  
Pratheek Bagivalu Prasanna ◽  
Sushrut G. Bapat ◽  
Ashok Midha ◽  
Vamsi Lodagala
Keyword(s):  
Rigid Body ◽  
Degrees Of Freedom ◽  
Compliant Mechanisms ◽  
Compliant Mechanism ◽  
Mode Shapes ◽  
Model Concept ◽  
Static Mode ◽  
Displacement Boundary ◽  
Body Model ◽  
Rigid Body Model

Abstract Traditionally, the deflected configuration of compliant segments is determined through rigorous mathematical analysis using Newtonian mechanics. Application of this approach in evaluating the deformed configuration of compliant mechanisms, containing a variety of segment types, becomes cumbersome. This paper introduces a methodology to determine the possible deflected configuration(s) of a compliant mechanism, for a given set of load and/or displacement boundary conditions. The methodology utilizes the principle of minimum potential energy, in conjunction with the degrees-of-freedom analysis and the pseudo-rigid-body model concept. The static mode shape(s) of compliant segments are integrated in identifying the possible deflected configuration(s) of a given compliant mechanism. The methodology facilitates the in situ determination of the possible deformed configuration(s) of the compliant mechanism and its constituent segments. This, in turn, assists in the important task of identifying an appropriate pseudo-rigid-body model for the design and analysis of a compliant mechanism. The proposed methodology is illustrated with examples, and supported with experimental validation.

A Numerical Method for Position Analysis of Compliant Mechanisms With More Degrees of Freedom Than Inputs

2010 ◽  
Author(s):  
Quentin T. Aten ◽  
Shannon A. Zirbel ◽  
Brian D. Jensen ◽  
Larry L. Howell
Keyword(s):  
Potential Energy ◽  
Rigid Body ◽  
Equilibrium Position ◽  
Degrees Of Freedom ◽  
Compliant Mechanisms ◽  
Virtual Work ◽  
Compliant Mechanism ◽  
Loop Equation ◽  
Body Model ◽  
Rigid Body Model

An under-actuated or underconstrained compliant mechanism may have a determined equilibrium position because its energy storage elements cause a position of local minimum potential energy. The minimization of potential energy (MinPE) method is a numerical approach to finding the equilibrium position of compliant mechanisms with more degrees of freedom (DOF) than inputs. Given the pseudo-rigid-body model of a compliant mechanism, the MinPE method finds the equilibrium position by solving a constrained optimization problem: minimize the potential energy stored in the mechanism, subject to the mechanism’s vector loop equation(s) being equal to zero. The MinPE method agrees with the method of virtual work for position and force determination for under-actuated 1-DOF and 2-DOF pseudo-rigid-body models. Experimental force-deflection data is presented for a fully compliant constant-force mechanism. Because the mechanism’s behavior is not adequately modeled using a 1-DOF pseudo-rigid-body model, a 13-DOF pseudo-rigid-body model is developed and solved using the MinPE method. The MinPE solution is shown to agree well with non-linear finite element analysis and experimental force-displacement data.

Conceptual Design and Kinematic Analysis of a Compliant Parallel Mechanism for Micro/Nano Scale Manipulation

2009 ◽  
Author(s):  
Dan Zhang ◽  
Beizhi Li ◽  
Jianguo Yang ◽  
Zhen Gao
Keyword(s):  
Degrees Of Freedom ◽  
Precision Manufacturing ◽  
Micro Electro Mechanical Systems ◽  
Flexure Hinges ◽  
Body Model ◽  
Nano Scale ◽  
Compliant Parallel Mechanism ◽  
Rigid Body Model ◽  
Kinematic Models ◽  
Optical Alignment

There is a great need in various fields to be able to produce motion on a micro/nano scale with three translational degrees of freedom (DOF). Such fields include optical alignment, cell injection operation, precision manufacturing and micro electro mechanical systems. This research is concerned with the design and analysis of a compliant parallel micromanipulator (CPM) for micro/nano scale manipulation. Several kinematic structures including a novel three-cylindrical-prismatic-revolute CPM is proposed. Based on the established pseudo-rigid-body model of the CPM, the kinematic models are derived. The CPM is featured by pizeo-driven and flexure hinges, thus it has advantages such as sub nanometer resolution, large force generation, sub-millisecond response, and extremely low steady state power consumption.

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