Multistability of Compliant Sarrus Mechanisms

2012 ◽  
Author(s):  
Guimin Chen ◽  
Shouyin Zhang
Keyword(s):  
Rigid Body ◽  
Compliant Mechanisms ◽  
Spatial Motion ◽  
Deployable Structures ◽  
Static Balancing ◽  
Compliant Joints ◽  
Body Method

Although there are many examples of multistable compliant mechanisms in the literature, most of them are of planar configurations. Considering that a multistable mechanism providing spatial motion could be useful in numerous applications, this paper explores the multistable behavior of the overconstrained spatial Sarrus mechanisms with compliant joints (CSMs). The kinetostatics of CSMs have been formulated based on the pseudo-rigid-body method. The kinetostatic results show that a CSM is capable of exhibiting bistability, tristability, and quadristability. Possible applications of multistable CSMs include deployable structures, static balancing of human/robot bodies and weight compensators.

Multistable Behaviors of Compliant Sarrus Mechanisms

2013 ◽  
Vol 5 (2) ◽  
Author(s):  
Guimin Chen ◽  
Shouyin Zhang ◽  
Geng Li
Keyword(s):  
Mechanism Analysis ◽  
Spatial Motion ◽  
Deployable Structures ◽  
Static Balancing ◽  
Compliant Joints ◽  
Type Of Behavior ◽  
Body Method

Multistable mechanisms providing spatial motion could be useful in numerous applications; this paper explores the multistable behavior of the overconstrained spatial Sarrus mechanisms with compliant joints (CSMs). The mechanism analysis is simplified by considering it as two submechanisms. The kinetostatics of CSMs have been formulated based on the pseudorigid-body method for compliant members at any combination of joints. The kinetostatic results show that a CSM is capable of exhibiting bistability, tristability, and quadristability. The type of behavior is found to depend on the initial (as-fabricated) position and the relative limit positions of the two submechanisms. Possible applications of multistable CSMs include deployable structures, static balancing of human/robot bodies, and weight compensators.

Application of Rigid-Body-Linkage Static Balancing Techniques to Reduce Actuation Effort in Compliant Mechanisms

2015 ◽  
Vol 8 (2) ◽  
Author(s):  
Sangamesh R. Deepak ◽  
Amrith N. Hansoge ◽  
G. K. Ananthasuresh
Keyword(s):  
Rigid Body ◽  
General Framework ◽  
Compliant Mechanisms ◽  
Compliant Mechanism ◽  
Small Length ◽  
Element Analysis ◽  
Static Balancing ◽  
Free Length ◽  
First Order ◽  
Taylor’S Series

There are analytical methods in the literature where a zero-free-length spring-loaded linkage is perfectly statically balanced by addition of more zero-free-length springs. This paper provides a general framework to extend these methods to flexure-based compliant mechanisms through (i) the well know small-length flexure model and (ii) approximation between torsional springs and zero-free-length springs. We use first-order truncated Taylor's series for the approximation between the torsional springs and zero-free-length springs so that the entire framework remains analytical, albeit approximate. Three examples are presented and the effectiveness of the framework is studied by means of finite-element analysis and a prototype. As much as 70% reduction in actuation effort is demonstrated. We also present another application of static balancing of a rigid-body linkage by treating a compliant mechanism as the spring load to a rigid-body linkage.

A Review on Compliant Joints and Rigid-Body Constant Velocity Universal Joints Toward the Design of Compliant Homokinetic Couplings

2015 ◽  
Vol 137 (3) ◽  
Author(s):  
D. Farhadi Machekposhti ◽  
N. Tolou ◽  
J. L. Herder
Keyword(s):  
Rigid Body ◽  
Constant Velocity ◽  
Compliant Mechanisms ◽  
Material Selection ◽  
Analytical Data ◽  
Graph Representations ◽  
Common Basis ◽  
Compliant Joints ◽  
Body Joints ◽  
Universal Joints

This paper presents for the first time a literature survey toward the design of compliant homokinetic couplings. The rigid-linkage-based constant velocity universal joints (CV joints) available from literature were studied, classified, their graph representations were presented, and their mechanical efficiencies compared. Similarly, literature is reviewed for different kinds of compliant joints suitable to replace instead of rigid-body joints in rigid-body CV joints. The compliant joints are compared based on analytical data. To provide a common basis for comparison, consistent flexure scales and material selection are used. It was found that existing compliant universal joints are nonconstant in velocity and designed based on rigid-body Hooke's universal joint. It was also discovered that no compliant equivalent exists for cylindrical, planar, spherical fork, and spherical parallelogram quadrilateral joints. We have demonstrated these compliant joints can be designed by combining existing compliant joints. The universal joints found in this survey are rigid-body non-CV joints, rigid-body CV joints, or compliant non-CV joints. A compliant homokinetic coupling is expected to combine the advantages of compliant mechanisms and constant velocity couplings for many applications where maintenance or cleanliness is important, for instance in medical devices and precision instruments.

Toward a Unified Design Approach for Both Compliant Mechanisms and Rigid-Body Mechanisms: Module Optimization

2015 ◽  
Vol 137 (12) ◽  
Author(s):  
Lin Cao ◽  
Allan T. Dolovich ◽  
Arend L. Schwab ◽  
Just L. Herder ◽  
Wenjun (Chris) Zhang
Keyword(s):  
Rigid Body ◽  
Compliant Mechanisms ◽  
Optimization Approach ◽  
Structure Model ◽  
Dimensional Synthesis ◽  
Beam Elements ◽  
Compliant Joints ◽  
Design Variables ◽  
Rigid Joints ◽  
Synthesis Approach

Rigid-body mechanisms (RBMs) and compliant mechanisms (CMs) are traditionally treated in significantly different ways. In this paper, we present a synthesis approach that is appropriate for both RBMs and CMs. In this approach, RBMs and CMs are generalized into modularized mechanisms that consist of five basic modules, including compliant links (CLs), rigid links (RLs), pin joints (PJs), compliant joints (CJs), and rigid joints (RJs). The link modules and joint modules are modeled through beam elements and hinge elements, respectively, in a geometrically nonlinear finite-element solver, and subsequently a beam-hinge ground structure model is proposed. Based on this new model, a link and joint determination approach—module optimization—is developed for the type and dimensional synthesis of both RBMs and CMs. In the module optimization approach, the states (both presence or absence and sizes) of joints and links are all design variables, and one may obtain an RBM, a partially CM, or a fully CM for a given mechanical task. Three design examples of path generators are used to demonstrate the effectiveness of the proposed approach to the type and dimensional synthesis of RBMs and CMs.

Criteria for the Static Balancing of Compliant Mechanisms

2010 ◽  
Author(s):  
Juan A. Gallego ◽  
Just L. Herder
Keyword(s):  
Energy Storage ◽  
Rigid Body ◽  
Strain Energy ◽  
Compliant Mechanisms ◽  
Design Methods ◽  
Static Balancing ◽  
Torsion Springs

Compliant mechanisms achieve their mobility through the deformation of their members, this means that part of the energy transmitted from the input to the output of the mechanisms will be stored in the mechanisms as strain energy. This energy storage in some cases is not a desired characteristic and a way to solve this problem is by static balancing the behavior of the mechanisms. Here five criteria are presented that can be used in the static balancing of compliant mechanisms. The criteria are combined in a systematic way with design methods for compliant mechanisms as an exercise to find feasible combinations for the development of design methods for statically balanced compliant mechanisms. The feasibility of the combination between criteria and design methods for compliant mechanisms is demonstrated by using rigid body mechanisms with torsion springs, roughly emulating their compliant counterpart.

An effective pseudo-rigid-body method for beam-based compliant mechanisms

2010 ◽  
Vol 34 (3) ◽  
pp. 634-639 ◽  
Author(s):  
Xu Pei ◽  
Jingjun Yu ◽  
Guanghua Zong ◽  
Shusheng Bi
Keyword(s):  
Rigid Body ◽  
Compliant Mechanisms ◽  
Body Method

scholarly journals Tuning of a Rigid-Body Dynamics Model of a Flapping Wing Structure With Compliant Joints

2017 ◽  
Vol 10 (1) ◽  
Author(s):  
Joseph Calogero ◽  
Mary Frecker ◽  
Zohaib Hasnain ◽  
James E. Hubbard
Keyword(s):  
Rigid Body ◽  
Motion Tracking ◽  
Compliant Mechanisms ◽  
Leading Edge ◽  
Rigid Body Dynamics ◽  
Model Parameters ◽  
Computationally Efficient ◽  
Dynamics Model ◽  
Compliant Joints ◽  
Body Dynamics

A method for validating rigid-body models of compliant mechanisms under dynamic loading conditions using motion tracking cameras and genetic algorithms is presented. The compliant mechanisms are modeled using rigid-body mechanics as compliant joints (CJ): spherical joints with distributed mass and three-axis torsional spring dampers. This allows compliant mechanisms to be modeled using computationally efficient rigid-body dynamics methods, thereby allowing a model to determine the desired stiffness and location characteristics of compliant mechanisms spatially distributed into a structure. An experiment was performed to validate a previously developed numerical dynamics model with the goal of tuning unknown model parameters to match the flapping kinematics of the leading edge spar of an ornithopter with contact-aided compliant mechanisms (CCMs), compliant mechanisms that feature self-contact to produce nonlinear stiffness, inserted. A system of computer motion tracking cameras was used to record the kinematics of reflective tape and markers placed along the leading edge spar with and without CCMs inserted. A genetic algorithm was used to minimize the error between the model and experimental marker kinematics. The model was able to match the kinematics of all markers along the spars with a root-mean-square error (RMSE) of less than 2% of the half wingspan over the flapping cycle. Additionally, the model was able to capture the deflection amplitude and harmonics of the CCMs with a RMSE of less than 2 deg over the flapping cycle.

Development of a 3-Spring Pseudo Rigid Body Model of Compliant Joints for Robotic Applications

2014 ◽  
Author(s):  
Venkatasubramanian Kalpathy Venkiteswaran ◽  
Hai-Jun Su
Keyword(s):  
Rigid Body ◽  
Compliant Mechanisms ◽  
Large Range ◽  
Beam Theory ◽  
Beam Model ◽  
Significant Challenge ◽  
Body Model ◽  
Compliant Joints ◽  
Rigid Body Model ◽  
Robotic Applications

Compliant mechanisms achieve motion utilizing deformation of elastic members. However, analysis of compliant mechanisms for large deflections remains a significant challenge. In this paper, we will develop a 3-spring pseudo-rigid-body model for 2D beams that are often used in compliant joints in robots. First, we utilize the Timoshenko beam theory to calculate the tip deflection for a large range of loading conditions. An optimization process is then carried out to calculate the values of the parameters of the PRB model. The errors in the model will be analyzed and compared to the beam model. An example based on a robotic grasper finger is provided to demonstrate how the model can be used in analysis of such a system. This model will provide a much simpler approach for the analysis of compliant robotic mechanisms.

A Simple and Accurate Method for Determining Large Deflections in Compliant Mechanisms Subjected to End Forces and Moments

1998 ◽  
Vol 120 (3) ◽  
pp. 392-400 ◽  
Author(s):  
A. Saxena ◽  
S. N. Kramer
Keyword(s):  
Rigid Body ◽  
Compliant Mechanisms ◽  
Compliant Mechanism ◽  
Elliptic Integral ◽  
Beam Equation ◽  
Large Deflections ◽  
Euler Beam ◽  
Body Model ◽  
Rigid Body Model ◽  
Analysis And Synthesis

Compliant members in flexible link mechanisms undergo large deflections when subjected to external loads. Because of this fact, traditional methods of deflection analysis do not apply. Since the nonlinearities introduced by these large deflections make the system comprising such members difficult to solve, parametric deflection approximations are deemed helpful in the analysis and synthesis of compliant mechanisms. This is accomplished by representing the compliant mechanism as a pseudo-rigid-body model. A wealth of analysis and synthesis techniques available for rigid-body mechanisms thus become amenable to the design of compliant mechanisms. In this paper, a pseudo-rigid-body model is developed and solved for the tip deflection of flexible beams for combined end loads. A numerical integration technique using quadrature formulae has been employed to solve the large deflection Bernoulli-Euler beam equation for the tip deflection. Implementation of this scheme is simpler than the elliptic integral formulation and provides very accurate results. An example for the synthesis of a compliant mechanism using the proposed model is also presented.

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