A Novel Fully Compliant Planar Linear-Motion Mechanism

2004 ◽  
Author(s):  
Neal B. Hubbard ◽  
Jonathan W. Wittwer ◽  
John A. Kennedy ◽  
Daniel L. Wilcox ◽  
Larry L. Howell
Keyword(s):  
Linear Motion ◽  
Element Analysis ◽  
Single Plane ◽  
Motion Mechanism ◽  
Body Model ◽  
Straight Line ◽  
Structural Error ◽  
Rigid Body Model ◽  
In Series ◽  
Force Displacement

A new fully compliant linear-motion mechanism, called the XBob, is presented. The mechanism is based on the pseudo-rigid-body model (PRBM) of a system of Roberts approximate straight-line mechanisms combined in series and parallel. It can be fabricated in a single plane and has a linear force-displacement relationship. Symmetry and compliance compensate for the structural error inherent in the Roberts mechanism, resulting in precise straight-line motion. The device is designed and its motion and force-displacement relations are predicted by the PRBM. The design is validated using finite element analysis and experimental results.

Design of a New Fully Compliant Translational Joint via Straight-Line Motion Mechanism Based Method

2019 ◽  
Author(s):  
Sonia C. García ◽  
Juan A. Gallego-Sanchez
Keyword(s):  
Rigid Body ◽  
Symmetry Axis ◽  
Initial Position ◽  
Element Analysis ◽  
Motion Mechanism ◽  
Body Model ◽  
Straight Line ◽  
Rigid Body Model ◽  
Translational Joint ◽  
Force Displacement

Abstract A Compliant Translational Joint (CTJ) is designed via Straight-Line Motion Mechanism Method. The designed CTJ is based on the Pseudo-Rigid-Body-Model (PRBM) of a modified Scott-Russell Mechanism. The precision of the straight-line motion of the rigid-body mechanism adjusts to a straight-line to a 99.6% while the compliant version adjusts to a 99.9%. The novelty of the design is given by the way the CTJ is designed, the performance of the CTJ is achieved by mirroring the mechanism about an axis tangent to the path of the mechanism and that passes through the initial position of the coupler point at the symmetry axis of the path. The CTJ motion is predicted by the PRBM. The force-displacement relations and the frequency modes of the CTJ are analyzed using finite element analysis (FEA).

Force-Displacement Model of the FlexSuRe™ Spinal Implant

2010 ◽  
Author(s):  
Eric Stratton ◽  
Larry Howell ◽  
Anton Bowden
Keyword(s):  
Rigid Body ◽  
Virtual Work ◽  
Implant Design ◽  
Element Analysis ◽  
Spinal Implant ◽  
Body Model ◽  
Flexion Extension ◽  
Rigid Body Model ◽  
Displacement Model ◽  
Force Displacement

This paper presents modeling of a novel compliant spinal implant designed to reduce back pain and restore function to degenerate spinal disc tissues as well as provide a mechanical environment conducive to healing of the tissues. Modeling was done through the use of the pseudo-rigid-body model. The pseudo-rigid-body model is a 3 DOF mechanism for flexion-extension (forward-backward bending) and a 5 DOF mechanism for lateral bending (side-to-side). These models were analyzed using the principle of virtual work to obtain the force-deflection response of the device. The model showed good correlation to finite element analysis and experimental results. The implant may be particularly useful in the early phases of implant design and when designing for particular biological parameters.

A Variable-Stiffness Straight-Line Compliant Mechanism

2015 ◽  
Author(s):  
Jeffrey C. Hawks ◽  
Mark B. Colton ◽  
Larry L. Howell
Keyword(s):  
Force Feedback ◽  
Compliant Mechanism ◽  
Variable Stiffness ◽  
Effective Length ◽  
Haptic Interface ◽  
Element Analysis ◽  
Straight Line ◽  
Rigid Body Model ◽  
Straight Line Mechanism ◽  
Force Displacement

In this research a variable-stiffness compliant mechanism was developed to generate variable force-displacement profiles at the mechanism’s coupler point. The mechanism is based on a compliant Robert’s straight-line mechanism, and the stiffness is varied by changing the effective length of the compliant links with an actuated slider. The force-deflection behavior of the mechanism was analyzed using the Pseudo-Rigid Body Model (PRBM), and two key parameters, KΘ and γ, were optimized using finite element analysis (FEA) to match the model with the measured behavior of the mechanism. The variable-stiffness mechanism was used in a one-degree-of-freedom haptic interface (force-feedback device) to demonstrate the effectiveness of varying the stiffness of a compliant mechanism. Unlike traditional haptic interfaces, in which the force is controlled using motors and rigid links, the haptic interface developed in this work displays haptic stiffness via the variable-stiffness compliant mechanism. One of the key features of the mechanism is that the inherent return-to-zero behavior of the compliant mechanism was used to provide the stiffness feedback felt by the user. A prototype haptic interface was developed capable of simulating the force-displacement profile of Lachman’s Test performed on an injured ACL knee. The compliant haptic interface was capable of displaying stiffnesses between 4200 N/m and 7200 N/m.

Design of a Single-Acting Constant-Force Actuator Based on Dielectric Elastomers

2008 ◽  
Author(s):  
Giovanni Berselli ◽  
Rocco Vertechy ◽  
Gabriele Vassura ◽  
Vincenzo Parenti Castelli
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Compliant Mechanism ◽  
Structural Parameters ◽  
Dielectric Elastomer ◽  
Constant Force ◽  
Element Analysis ◽  
Body Model ◽  
Rigid Body Model ◽  
Supporting Frame

The interest in actuators based on dielectric elastomer films as a promising technology in robotic and mechatronic applications is increasing. The overall actuator performances are influenced by the design of both the active film and the film supporting frame. This paper presents a single-acting actuator which is capable of supplying a constant force over a given range of motion. The actuator is obtained by coupling a rectangular film of silicone dielectric elastomer with a monolithic frame designed to suitably modify the force generated by the dielectric elastomer film. The frame is a fully compliant mechanism whose main structural parameters are calculated using a pseudo-rigid-body model and then verified by finite element analysis. Simulations show promising performance of the proposed actuator.

The Mixed-Body Model: A Method for Predicting Large Deflections in Stepped Cantilever Beams

2021 ◽  
pp. 1-18
Author(s):  
Brandon Sargent ◽  
Collin Ynchausti ◽  
Todd G Nelson ◽  
Larry L Howell
Keyword(s):  
Large Deflections ◽  
Cantilever Beams ◽  
Element Analysis ◽  
Body Model ◽  
Minimal Error ◽  
Small Deflection ◽  
Rigid Body Model ◽  
Expected Values ◽  
Deflection Theory ◽  
Sample Set

Abstract This paper presents a method for predicting endpoint coordinates, stress, and force to deflect stepped cantilever beams under large deflections. This method, the Mixed-Body Model or MBM, combines small deflection theory and the Pseudo-Rigid-Body Model for large deflections. To analyze the efficacy of the model, the MBM is compared to a model that assumes the first step in the beam to be rigid, to finite element analysis, and to the numerical boundary value solution over a large sample set of loading conditions, geometries, and material properties. The model was also compared to physical prototypes. In all cases, the MBM agrees well with expected values. Optimization of the MBM parameters yielded increased agreement, leading to average errors of <0.01 to 3%. The model provides a simple, quick solution with minimal error that can be particularly helpful in design.

Large Stroke Series Compliant Mechanism

2012 ◽  
Vol 490-495 ◽  
pp. 1104-1108 ◽  
Author(s):  
Ming Cai Shan ◽  
Wei Ming Wang ◽  
Shu Yuan Ma ◽  
Shuang Liu
Keyword(s):  
Theoretical Model ◽  
Maximum Stress ◽  
Compliant Mechanism ◽  
Critical Parameters ◽  
Element Analysis ◽  
Flexure Hinges ◽  
Body Model ◽  
System A ◽  
Rigid Body Model ◽  
The Difference

To increase the stroke of precision positioning system, a novel series compliant mechanism is presented which is based on elliptical flexure hinges. Pseudo-rigid-body model and energy method are applied to establish the theoretical model of stiffness and maximum stress, which are critical parameters for the large stroke compliant mechanism. The relationships are analyzed between geometric parameters of the series complaint mechanism, stiffness and maximum stress. According that, the series compliant mechanism is designed with the stroke more than 5mm and stiffness less than 3.2N/mm. The difference is less than 5% between the results of finite element analysis and theoretical model computation, which proves the correctness of the application design.

scholarly journals Design and Validation of a Single-SOI-Wafer 4-DOF Crawling Microgripper

Micromachines ◽  
2019 ◽  
Vol 10 (6) ◽  
pp. 376 ◽  
Author(s):  
Matteo Verotti ◽  
Alvise Bagolini ◽  
Pierluigi Bellutti ◽  
Nicola Pio Belfiore
Keyword(s):  
Finite Element Analysis ◽  
Rigid Body ◽  
Compliant Mechanism ◽  
Silicon On Insulator ◽  
Element Analysis ◽  
Deep Reactive Ion Etching ◽  
Theoretical Simulation ◽  
Body Model ◽  
Replacement Method ◽  
Rigid Body Model

This paper deals with the manipulation of micro-objects operated by a new concept multi-hinge multi-DoF (degree of freedom) microsystem. The system is composed of a planar 3-DoF microstage and of a set of one-DoF microgrippers, and it is arranged is such a way as to allow any microgripper to crawl over the stage. As a result, the optimal configuration to grasp the micro-object can be reached. Classical algorithms of kinematic analysis have been used to study the rigid-body model of the mobile platform. Then, the rigid-body replacement method has been implemented to design the corresponding compliant mechanism, whose geometry can be transferred onto the etch mask. Deep-reactive ion etching (DRIE) is suggested to fabricate the whole system. The main contributions of this investigation consist of (i) the achievement of a relative motion between the supporting platform and the microgrippers, and of (ii) the design of a process flow for the simultaneous fabrication of the stage and the microgrippers, starting from a single silicon-on-insulator (SOI) wafer. Functionality is validated via theoretical simulation and finite element analysis, whereas fabrication feasibility is granted by preliminary tests performed on some parts of the microsystem.

A Pseudo-Rigid-Body Model for Rolling-Contact Compliant Beams

2007 ◽  
Author(s):  
Allen B. Mackay ◽  
Spencer P. Magleby ◽  
Larry L. Howell
Keyword(s):  
Rigid Body ◽  
Rolling Contact ◽  
Model Parameters ◽  
Displacement Curve ◽  
Cantilever Beams ◽  
Body Model ◽  
Rigid Body Model ◽  
Contact Surfaces ◽  
Definition Of ◽  
Force Displacement

This paper presents a pseudo-rigid-body model (PRBM) for rolling-contact compliant beams (RCCBs). The loading conditions and boundary conditions for the RCCB can be simplified to an equivalent cantilever beam that has the same force-deflection characteristics as the RCCB. Building on the PRBM for cantilever beams, this paper defines a model for the force-deflection relationship for RCCBs. The definition of the RCCB PRBM includes the pseudo-rigid-body model parameters that determine the shape of the beam, the length of the corresponding pseudo-rigid-body links and the stiffness of the equivalent torsional spring. The behavior of the RCCB is parameterized in terms of a single parameter defined as clearance, or the distance between the contact surfaces. RCCBs exhibit a unique force-displacement curve where the force is inversely proportional to the clearance squared.

The Compliant A-Arm Suspension

Aerospace ◽  
2003 ◽  
Author(s):  
Timothy Allred ◽  
Larry L. Howell ◽  
Spencer P. Magleby ◽  
Robert H. Todd
Keyword(s):  
Compliant Mechanisms ◽  
Commercial Application ◽  
Leaf Spring ◽  
Large Deflections ◽  
Element Analysis ◽  
Performance Variables ◽  
Body Model ◽  
Small Deflection ◽  
Rigid Body Model ◽  
Depth Study

The use compliant mechanisms in a suspension system has been demonstrated with leaf spring mechanisms. In this research a novel compliant configuration called the Compliant A-Arm (C-A-Arm) suspension is selected for in-depth study. Closed-from equations are derived for linear small-deflection stiffness equations. Large deflections are analyzed using finite element analysis. A pseudo-rigid-body model is developed to approximate mechanism deflections and stiffness for large deflections. The results suggest that the C-A-Arm configuration may be a viable suspension alternative for future commercial application. In addition, this configuration offers a number of performance variables that could be the basis for an active control system. This paper represents a necessary first step in modeling this new configuration.

The Mixed-Body Model: A Method for Predicting Large Deflections in Stepped Cantilever Beams

2021 ◽  
Author(s):  
Brandon S. Sargent ◽  
Collin R. Ynchausti ◽  
Todd G. Nelson ◽  
Larry L. Howell
Keyword(s):  
Large Deflections ◽  
Cantilever Beams ◽  
Element Analysis ◽  
Body Model ◽  
Minimal Error ◽  
Small Deflection ◽  
Rigid Body Model ◽  
Expected Values ◽  
Deflection Theory ◽  
Sample Set

Abstract This paper presents a method for predicting endpoint coordinates, stress, and force to deflect stepped cantilever beams under large deflections. This method, the Mixed-Body Model or MBM, combines small deflection theory and the Pseudo-Rigid-Body Model for large deflections. To analyze the efficacy of the model, the MBM is compared to a model that assumes the first step in the beam to be rigid, to finite element analysis, and to the numerical boundary value solution over a large sample set of loading conditions, geometries, and material properties. The model was also compared to physical prototypes. In all cases, the MBM agrees well with expected values. Optimization of the MBM parameters yielded increased agreement, leading to average errors of < 0.01 to 3%. The model provides a simple, quick solution with minimal error that can be particularly helpful in design.

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