A Three Degree-of-Freedom Model for Self-Retracting Fully Compliant Bistable Micromechanisms

2005 ◽  
Vol 127 (4) ◽  
pp. 739-744 ◽  
Author(s):  
Nathan D. Masters ◽  
Larry L. Howell
Keyword(s):  
Rigid Body ◽  
Design Process ◽  
Compressive Loading ◽  
Fatigue Tests ◽  
Critical Force ◽  
Degree Of Freedom ◽  
Small Displacement ◽  
New Class ◽  
Rigid Body Model ◽  
Three Degree Of Freedom

A three degree-of-freedom (3DOF) pseudo-rigid-body model (PRBM) has been developed and used in the design of a new class of self-retracting fully compliant bistable micromechanism (SRFBM). The SRFBM provides small-displacement linear travel bistability and is suitable for low-power microswitching applications. The design process involved a combination of single and multiple degree-of-freedom PRBM and finite element models to quickly proceed from a concept rigid-body mechanism to fully compliant fabrication-ready geometry. The 3DOF model presented here was developed to more accurately model the behavior of the tensural pivots—a new class of compliant segment used to avoid combined compressive loading of flexible segments. Four SRFBM designs were fabricated and tested for bistability, on-chip actuation, critical force, and fatigue tests. These tests validate the models used in the design process and demonstrate the functionality and reliability of the SRFBM.

Improved Development Cycle of a Compliant Manipulator

2003 ◽  
Author(s):  
Stephen L. Canfield ◽  
Patrick V. Hull ◽  
James W. Beard
Keyword(s):  
Design Process ◽  
Design Methodology ◽  
Low Cost ◽  
Parallel Architecture ◽  
Degree Of Freedom ◽  
Modeling Tools ◽  
Multiple Features ◽  
Positioning Accuracy ◽  
Development Cycle ◽  
Three Degree Of Freedom

Application of the compliant design methodology to manipulators has held the promise of delivering manipulators with many significant advantages, including low cost, small size, low backlash and friction, and high positioning accuracy. This approach has been demonstrated in part by Canfield et. al., [1] to a class of three-degree-of-freedom manipulators based on a specific parallel architecture topology. In [1], the authors’ intent was to develop two compliant manipulators that exhibit several of the features associated with compliant devices. However, upon review of the manipulators resulting from this work it is observed that many of the benefits that were expected were lost at some point in the design process, resulting in manipulators that were large, expensive and suffered significantly from required assembly and inaccuracies in manufacture. This paper will revisit the problem addressed in [1], using the modeling tools demonstrated in that paper but will present several improved development measures that will result in manipulators that exhibit multiple features promised by compliant devices. The resulting manipulators will then be compared against the manipulators from [1] with a summary of the performance and characteristics of each given and evaluated.

Compliant Wireform Mechanisms

2008 ◽  
Vol 130 (12) ◽  
Author(s):  
Tyler M. Pendleton ◽  
Brian D. Jensen
Keyword(s):  
Rigid Body ◽  
Compliant Mechanisms ◽  
Finite Element Models ◽  
Simplified Models ◽  
New Class ◽  
Body Model ◽  
Single Piece ◽  
Rigid Body Model ◽  
Torsion Springs ◽  
Torsion Bar

This paper presents an alternative to fabrication methods commonly used in compliant mechanisms research, resulting in a new class of compliant mechanisms called wireform mechanisms. This technique integrates torsional springs made of formed wire into compliant mechanisms. In this way the desired force, stiffness, and motion can be achieved from a single piece of formed wire. Two techniques of integrating torsion springs are fabricated and modeled: helical coil torsion springs and torsion bars. Because the mechanisms are more complex than ordinary springs, simplified models, which aid in design, are presented, which represent the wireform mechanisms as rigid-body mechanisms using the pseudo-rigid-body model. The method is demonstrated through the design of a mechanically tristable mechanism. The validity of the simplified models is discussed by comparison to finite element models and, in the case of the torsion-bar mechanism, to experimental measurements.

Dimensional Synthesis of Planar Eight-Bar Linkages Based on a Parallel Robot With a Prismatic Base Joint

2013 ◽  
Author(s):  
Gim Song Soh ◽  
Fangtian Ying
Keyword(s):  
Rigid Body ◽  
Design Process ◽  
Parallel Robot ◽  
Degree Of Freedom ◽  
Dimensional Synthesis ◽  
End Effector ◽  
Prismatic Joint ◽  
Serial Chain ◽  
Different Types

This paper details the dimensional synthesis for the rigid body guidance of planar eight-bar linkages that could be driven by a prismatic joint at its base. We show how two RR cranks can be added to a planar parallel robot formed by a PRR and 3R serial chain to guide its end-effector through a set of five task poses. This procedure is useful for designers who require the choice of ground pivot locations. The results are eight different types of one-degree of freedom planar eight-bar linkages. We demonstrate the design process with the design of a multifunctional wheelchair that could transform its structure between a self-propelled wheelchair and a walking guide.

Passage Through Resonance in a Vibration Isolation System (Effects of Rate of Increasing the Voltage Applied to D.C. Motor)

2007 ◽  
Author(s):  
Tomohiko Tange ◽  
Ryo Kawana ◽  
Tetsuro Tokoyoda ◽  
Masatsugu Yoshizawa ◽  
Toshihiko Sugiura
Keyword(s):  
Rigid Body ◽  
Internal Resonance ◽  
Vibration Isolation ◽  
Transient Behavior ◽  
Degree Of Freedom ◽  
Isolation System ◽  
Vibration Isolation System ◽  
Rotational Vibration ◽  
Three Degree Of Freedom ◽  
Driving Torque

This paper deals with transient nonlinear vibration of a rigid body suspended on a foundation by elastic springs and constrained in a plane. In such a three degree-of-freedom vibration isolation system, we assume that ‘2-1-1’ internal resonance exists between the vertical and horizontal vibrations of the rigid body and the rotational vibration about its center of gravity. Our main purpose is to examine theoretically the transient behavior passing through resonance under the condition that the D.C. motor directly drives the unbalanced rotor. Numerical simulation was carried out to clarify effects of rate of increasing V(t) on the peak amplitude of the vibration of the rigid body and on the driving torque of the D.C. motor. Moreover, experiment was conducted with a physical model of a three degree-of-freedom vibration isolation system, and the transient behavior passing through resonance was observed and compared with theoretical results in a typical case with internal resonance.

Effects of Aerodynamics on Line Sail During Parachute Deployment

2021 ◽  
Author(s):  
Mingzhang Tang ◽  
Liwu Wang ◽  
Yu Liu ◽  
Sijun Zhang
Keyword(s):  
Rigid Body ◽  
Dynamic Model ◽  
Space Vehicle ◽  
Degree Of Freedom ◽  
Recovery System ◽  
On Line ◽  
Parachute System ◽  
Six Degree Of Freedom ◽  
Three Degree Of Freedom ◽  
Mass Spring

Abstract This paper presents a dynamic model to numerically simulate the parachute deployment for space vehicle recovery system. In the proposed dynamic model, the deployment bag and the space vehicle are treated as a six-degree-of-freedom rigid body with mass varied and a regular six-degree-of-freedom rigid body, respectively. The parachute system is considered as the mass spring damper model, in which the canopy, suspension lines, risers and bridles are discretized into some three-degree-of-freedom segments with their centralized mass on the end points. During the deployment a notable phenomenon can be observed and so-called line sail. The line sail generally occurs during a deployment in which the relative wind is not parallel to the deployment direction. The line sail has been known to cause or contribute to the following problems: increased deployment times, changes in snatch load, asymmetrical deployment, friction damage, and unpredictable canopy inflation. To understand its mechanisms, the effects of aerodynamics such as angle of flight path, deployment bag ejection velocity, Mach number, air density and wind velocity are numerically investigated.

A DIFFERENTIAL GEOMETRIC METHOD FOR KINEMATIC ANALYSIS OF TWO- AND THREE-DEGREE-OF-FREEDOM RIGID BODY MOTIONS*

2002 ◽  
Vol 30 (3) ◽  
pp. 279-307
Author(s):  
Sandipan Bandyopadhyay ◽  
Ashitava Ghosal ◽  
Bahram Ravani
Keyword(s):  
Rigid Body ◽  
Kinematic Analysis ◽  
Degree Of Freedom ◽  
Geometric Method ◽  
Rigid Body Motions ◽  
Three Degree Of Freedom

Improved Pseudo-Rigid-Body Model Parameter Values for End-Force-Loaded Compliant Beams

2004 ◽  
Author(s):  
Joby Pauly ◽  
Ashok Midha
Keyword(s):  
Rigid Body ◽  
Design Process ◽  
Compliant Mechanism ◽  
Model Parameters ◽  
Body Model ◽  
Axial Tensile ◽  
Rigid Body Model ◽  
Analysis And Synthesis ◽  
Parameter Values ◽  
Compliant Mechanism Design

Pseudo-rigid-body models help expedite the compliant mechanism design process by aiding the analysis and synthesis of candidate design solutions, using loop-closure techniques for rigid-body mechanisms. Opportunities for improvement were observed in the values of pseudo-rigid-body model parameters for compliant beams with nearly axial, tensile end force loads. This paper presents improved values for the affected parameters.

Double-Young Tristable Mechanisms

2012 ◽  
Vol 5 (1) ◽  
Author(s):  
Guimin Chen ◽  
Yunlei Du
Keyword(s):  
Stable Equilibrium ◽  
Design Method ◽  
Degree Of Freedom ◽  
New Class ◽  
Three Degree Of Freedom ◽  
Optimization Based Design

In this work, we present a new class of tristable mechanism called double Young tristable mechanisms (DYTMs), which connect two prestrained Young bistable mechanisms to create three distinct stable equilibrium positions. A three-degree-of-freedom pseudorigid-body (RPB) model is proposed to accurately predict the kinetostatic behaviors of both Young mechanisms and DYTMs. An optimization-based design method is also presented for DYTMs. Two DYTM prototypes were designed based on the method and machined out of polypropylene sheets. Both of the prototypes exhibit tristability, which demonstrate the feasibility of achieving tristability through connecting two prestrained Young mechanisms. The successful prototyping also indicates that the proposed three degree-of-freedom (3DOF) model is capable of identifying feasible designs for DYTMs.

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