Design of a Constant-Force Flexure Micropositioning Stage With Long Stroke

2015 ◽  
Author(s):  
Qingsong Xu
Keyword(s):  
Parametric Design ◽  
Compliant Mechanism ◽  
Analytical Models ◽  
Constant Force ◽  
Force Output ◽  
Element Analysis ◽  
Flexure Mechanism ◽  
Bistable Structure ◽  
Bistable Mechanism ◽  
Long Stroke

This paper presents the design and analysis a flexure-guided compliant micropositioning stage with constant force and large stroke. The constant force output is achieved by combining a bistable flexure mechanism with a positive-stiffness flexure mechanism. In consideration of the constraint of conventional tilted beam-based bistable mechanism, a new type of bistable structure based on tilted-angle compound parallelogram flexure is proposed to achieve a larger range of constant force output while maintaining a compact physical size. To facilitate the parametric design of the flexure mechanism, analytical models are derived to quantify the stage performance. The models are verified by carrying out nonlinear finite-element analysis. Results demonstrate the effectiveness of the proposed ideas for a long-stroke, constant-force compliant mechanism dedicated to precision micropositioning applications.

Design of a Large-Stroke Bistable Mechanism for the Application in Constant-Force Micropositioning Stage

2016 ◽  
Vol 9 (1) ◽  
Author(s):  
Qingsong Xu
Keyword(s):  
Parametric Design ◽  
Compliant Mechanism ◽  
Analytical Models ◽  
Constant Force ◽  
Force Output ◽  
Element Analysis ◽  
Flexure Mechanism ◽  
Study Results ◽  
Bistable Structure ◽  
Bistable Mechanism

To overcome the constraint of conventional tilted beam-based bistable mechanism, this paper proposes a novel type of bistable structure based on tilted-angle compound parallelogram flexure to achieve a larger stroke of negative stiffness region while maintaining a compact physical size. As an application of the presented bistable mechanism, a flexure constant-force micropositioning stage is designed to deliver a large stroke. The constant force output is obtained by combining a bistable flexure mechanism with a positive-stiffness flexure mechanism. To facilitate the parametric design of the flexure mechanism, analytical models are derived to quantify the stage performance. The models are verified by carrying out nonlinear finite-element analysis (FEA). A metal prototype is fabricated for experimental study. Results demonstrate the effectiveness of the proposed ideas for a long-stroke, constant-force compliant mechanism dedicated to precision micropositioning applications. Experimental results also show the appearance of two-stage constant force due to the manufacturing errors of the bistable beams.

scholarly journals A bistable mechanism with linear negative stiffness and large in-plane lateral stiffness: design, modeling and case studies

2020 ◽  
Vol 11 (1) ◽  
pp. 75-89 ◽  
Author(s):  
Zhanfeng Zhou ◽  
Yongzhuo Gao ◽  
Lining Sun ◽  
Wei Dong ◽  
Zhijiang Du
Keyword(s):  
Vibration Isolation ◽  
Compliant Mechanism ◽  
Dynamic Stiffness ◽  
Negative Stiffness ◽  
Analytical Models ◽  
Lateral Stiffness ◽  
Constant Force ◽  
The Novel ◽  
Stiffness Characteristic ◽  
Bistable Mechanism

Abstract. To overcome the limitations of conventional bistable mechanisms, this paper proposes a novel type of bistable mechanism with linear negative stiffness and large in-plane lateral stiffness. By connecting the novel negative-stiffness mechanism in parallel with a positive-stiffness mechanism, a novel quasi-zero stiffness compliant mechanism is developed, which has good axial guidance capability and in-plane lateral anti-interference capability. Analytical models based on a comprehensive elliptic integral solution of bistable mechanism are established and then the stiffness curves of both conventional and novel bistable mechanisms are analyzed. The quasi-zero stiffness characteristic and High-Static-Low-Dynamic-Stiffness characteristic of the novel compliant mechanism are investigated and its application in constant-force mechanism and vibration isolator is discussed. A prototype with adjustable load-carrying capacity is designed and fabricated for experimental study. In the two experiments, the effectiveness of the proposed quasi-zero stiffness mechanism used in the field of constant-force output and vibration isolation is tested.

Simplified modelling and development of a bi-directionally adjustable constant-force compliant gripper

2016 ◽  
Vol 231 (11) ◽  
pp. 2110-2123 ◽  
Author(s):  
Guangbo Hao ◽  
John Mullins ◽  
Kevin Cronin
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Negative Stiffness ◽  
Displacement Curve ◽  
Constant Force ◽  
Force Output ◽  
Element Analysis ◽  
Force Mechanism ◽  
Bistable Mechanism ◽  
Constant Force Mechanism

This paper proposes the design of a wholly mechanical constant-force gripper that can accommodate the imprecise manipulation of brittle/delicate objects by the actuation. This was achieved by designing a constant-force mechanism as the jaw that allowed a constant force to be applied to the grasping objects regardless of the displacement of the mechanism. The constant-force mechanism is attached to the end effector of the gripper via a parallelogram mechanism which ensures that the jaws remain in parallel. The constant-force mechanism combines the negative stiffness of a bistable mechanism and the positive stiffness of a linear spring to generate a constant force output. By preloading the positive stiffness mechanism, the magnitude of the constant force can be adjusted to be as low as zero. The constant-force mechanism has been fully modelled and simulated using finite element analysis. A normalised force-displacement curve has been developed that allows to obtain the simplified analytical negative stiffness of the bistable mechanism. The design formulation to find the optimal configuration that produces the most constant force has been developed. Illustrated experiments prove the concept of the design although the discrepancies between finite element analysis results and testing results exist due to bistable beam manufacturing error.

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.

Bistable Compliant Four-Bar Mechanisms With a Single Torsional Spring

2006 ◽  
Author(s):  
Adarsh Mavanthoor ◽  
Ashok Midha
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Mechanism Design ◽  
Compliant Mechanisms ◽  
Compliant Mechanism ◽  
Stored Energy ◽  
Element Analysis ◽  
Bistable Behavior ◽  
Torsional Spring ◽  
Bistable Mechanism

Significant reduction in cost and time of bistable mechanism design can be achieved by understanding their bistable behavior. This paper presents bistable compliant mechanisms whose pseudo-rigid-body models (PRBM) are four-bar mechanisms with a torsional spring. Stable and unstable equilibrium positions are calculated for such four-bar mechanisms, defining their bistable behavior for all possible permutations of torsional spring locations. Finite Element Analysis (FEA) and simulation is used to illustrate the bistable behavior of a compliant mechanism with a straight compliant member, using stored energy plots. These results, along with the four-bar and the compliant mechanism information, can then be used to design a bistable compliant mechanism to meet specified requirements.

The Design and Analysis of a Compliant Constant-Force Mechanism

2016 ◽  
Author(s):  
Zhongtian Xie ◽  
Lifang Qiu
Keyword(s):  
Compliant Mechanism ◽  
Reaction Force ◽  
Constant Force ◽  
Element Analysis ◽  
Fea Model ◽  
Electrical Connector ◽  
Force Mechanism ◽  
Input Motion ◽  
Operational Range ◽  
Constant Force Mechanism

Compliant constant-force mechanisms (CFM) are a type of compliant mechanism which produce a reaction force at the output port that does not change for a large range of input motion. This paper describes a new compliant CFM, introduces its design and configuration-improvement process. A finite element analysis (FEA) model of the compliant CFM was created to evaluate its constant force behavior. The FEA result shows that when the displacement is Δ = 4 mm, the compliant CFM maintains a nearly constant force in the operational displacement range of 1.31 mm to 4 mm with an error of 5.05%. The operational range accounts for 67% of the total motion. This compliant CFM can be used to regulate the contact force of a robot end-effector or as an electrical connector.

On the Design of a Long-Stroke Beam-Based Compliant Mechanism Providing Quasi-Constant Force

2019 ◽  
Author(s):  
Pietro Bilancia ◽  
Alessandro Geraci ◽  
Giovanni Berselli
Keyword(s):  
Compliant Mechanism ◽  
Design Method ◽  
Reaction Force ◽  
Constant Force ◽  
Physical Prototype ◽  
Flexible Behavior ◽  
Improved Design ◽  
The One ◽  
Long Stroke ◽  
Integrated Software

Abstract In this paper the design of a linear long-stroke quasi-constant force compliant mechanism (CM) is presented and discussed. Starting from a flexure-based slider-crank mechanism, providing the required constant force within a rather limited deflection range, the paper reports about the shape optimization carried out with the specific aim of extending the available CM operative range. The proposed device is suitable in several precision manipulation systems, which require to maintain a constant-force at their contact interface with the manipulated object. Force regulation is generally achieved by means of complex control algorithms and related sensory apparatus, resulting in a flexible behavior but also in high costs. A valid alternative may be the use of a purposely designed CM, namely a purely mechanical system whose shape and dimensions are optimized so as to provide a force-deflection behavior characterized by zero stiffness. In the first design step, the Pseudo-Rigid Body (PRB) method is exploited to synthesize the sub-optimal compliant configuration, i.e. the one characterized by lumped compliance. Secondly, an improved design alternative is evaluated resorting to an integrated software framework, comprising Matlab and ANSYS APDL, and capable of performing non-linear structural optimizations. The new embodiment makes use of a variable thickness beam, whose shape and dimensions have been optimized so as to provide a constant reaction force in an extended range. Finally, a physical prototype of the beam-based configuration is produced and tested, experimentally validating the proposed design method.

An Adjustable Constant-Force Mechanism for Adaptive End-Effector Operations

2012 ◽  
Vol 134 (3) ◽  
Author(s):  
Yi-Ho Chen ◽  
Chao-Chieh Lan
Keyword(s):  
Compliant Mechanism ◽  
Displacement Curve ◽  
Constant Force ◽  
Force Output ◽  
Control Effort ◽  
End Effector ◽  
Linear Spring ◽  
End Effectors ◽  
Force Mechanism ◽  
Constant Force Mechanism

Force regulation is a challenging problem for robot end-effectors when interacting with an unknown environment. It often requires sophisticated sensors with computerized control. This paper presents an adjustable constant-force mechanism (ACFM) to passively regulate the contact force of a robot end-effector. The proposed ACFM combines the negative stiffness of a bistable mechanism and positive stiffness of a linear spring to generate a constant-force output. Through prestressing the linear spring, the constant-force magnitude can be adjusted to adapt to different working environments. The ACFM is a monolithic compliant mechanism that has no frictional wear and is capable of miniaturization. We propose a design formulation to find optimal mechanism configurations that produce the most constant-force. A resulting force to displacement curve and maximal stress curve can be easily manipulated to fit a different application requirement. Illustrated experiments show that an end-effector equipped with the ACFM can adapt to a surface of variable height, without additional motion programming. Since sensors and control effort are minimized, we expect this mechanism can provide a reliable alternative for robot end-effectors to interact friendly with an environment.

scholarly journals Design, Analysis and Testing of a New Compliant Compound Constant-Force Mechanism

Actuators ◽  
2018 ◽  
Vol 7 (4) ◽  
pp. 65 ◽  
Author(s):  
Xiaozhi Zhang ◽  
Guangwei Wang ◽  
Qingsong Xu
Keyword(s):  
Maximum Stress ◽  
Contact Process ◽  
Constant Force ◽  
Force Output ◽  
Element Analysis ◽  
Input Force ◽  
Force Structure ◽  
Force Mechanism ◽  
Design And Testing ◽  
Constant Force Mechanism

This paper presents the design and testing of a novel flexure-based compliant compound constant-force mechanism (CCFM). One uniqueness of the proposed mechanism lies in that it achieves both constant-force input and constant-force output, which is enabled by integrating two types of sub-mechanisms termed active and passive constant-force structures, respectively. Unlike conventional structures, the active constant-force structure allows the reduction on input force requirement and thus the enlargement of motion stroke provided that the maximum stress of the material is within allowable value. While the passive one offers a safe environmental interaction during the contact process. Analytical model of the proposed CCFM is derived which is verified by simulation study with finite element analysis (FEA). A prototype mechanism is fabricated by a 3D printer to demonstrate the performance of the proposed CCFM design. Experimental results reveal the effectiveness of the reported CCFM.

Bistable Compliant Mechanism Using Magneto Active Elastomer Actuation

2014 ◽  
Author(s):  
Adrienne Crivaro ◽  
Rob Sheridan ◽  
Mary Frecker ◽  
Timothy W. Simpson ◽  
Paris von Lockette
Keyword(s):  
Magnetic Particles ◽  
Compliant Mechanism ◽  
Element Analysis ◽  
Fea Model ◽  
Embedded Particles ◽  
Substrate Properties ◽  
Bistable Mechanism ◽  
The Relationship ◽  
Elastomer Actuation ◽  
Origami Engineering

In the emerging field of origami engineering, it is important to investigate ways to achieve large deformations to enable significant shape transformations. One way to achieve this is through the use of bistable mechanisms. The goal in this research is to investigate the feasibility and design of a compliant bistable mechanism that is actuated by magneto active elastomer (MAE) material. The MAE material has magnetic particles embedded in the material that are aligned during the curing process. When exposed to an external field, the material deforms to align the embedded particles with the field. We investigate actuation of the MAE material through the development of finite element analysis (FEA) models to predict the magnetic field required to snap the device from its first stable position to its second for various geometries and field strengths. The FEA model also predicts the displacement of the center of the mechanism as it moves from one position to the other to determine if the device is in fact bistable. These results help show the relationship between the substrate properties and the bistability of the device. Experimental results validate the FEA models and demonstrate the functionality of active materials to be used as actuators for such devices and applications of origami engineering.

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