Design of a Compliant Mechanism to Modify an Actuator Characteristic to Deliver a Constant Output Force

2006 ◽  
Vol 128 (5) ◽  
pp. 1101 ◽  
Author(s):  
C. B. W. Pedersen ◽  
N. A. Fleck ◽  
G. K. Ananthasuresh
Keyword(s):  
Compliant Mechanism ◽  
Output Force ◽  
Constant Output

A Two-Dimensional Adjustable Constant-Force Mechanism

2019 ◽  
Vol 142 (6) ◽  
Author(s):  
Yu-Ling Kuo ◽  
Chao-Chieh Lan
Keyword(s):  
Limited Range ◽  
Two Dimensions ◽  
Working Environment ◽  
Design Parameters ◽  
Constant Force ◽  
Two Dimensional ◽  
Output Force ◽  
Constant Output ◽  
Force Variation ◽  
Force Mechanism

Abstract Constant-force mechanisms (CFMs) can produce an almost invariant output force over a limited range of input displacement. Without using additional sensor and force controller, adjustable CFMs can passively produce an adjustable constant output force to interact with the working environment. In the literature, one-dimensional CFMs have been developed for various applications. This paper presents the design of a novel CFM that can produce adjustable constant force in two dimensions. Because an adjustable constant force can be produced in each radial direction, the proposed adjustable CFM can be used in applications that require two-dimensional force regulation. In this paper, the design formulation and simulation results are presented and discussed. Equations to minimize the output force variation are given to choose the design parameters optimally. A prototype of the two-dimensional CFM is tested to demonstrate the effectiveness and accuracy of adjustable force regulation. This novel CFM is expected to be used in machines or robots to interact friendly with the environment.

scholarly journals Design of a Compliant Mechanism Based Four-Stage Amplification Piezoelectric-Driven Asymmetric Microgripper

Micromachines ◽  
2019 ◽  
Vol 11 (1) ◽  
pp. 25
Author(s):  
Xiaodong Chen ◽  
Zilong Deng ◽  
Siya Hu ◽  
Jinhai Gao ◽  
Xingjun Gao
Keyword(s):  
Compliant Mechanism ◽  
Experimental Tests ◽  
Element Analysis ◽  
Output Displacement ◽  
Amplification Ratio ◽  
Output Force ◽  
Characteristics Analysis ◽  
The Relationship ◽  
Two Sides ◽  
Theoretical Results

The existing symmetrical microgrippers have larger output displacements compared with the asymmetrical counterparts. However, the two jaws of a symmetrical microgripper are less unlikely to offer the same forces on the two sides of a grasped micro-object due to the manufacture and assembly errors. Therefore, this paper proposes a new asymmetric microgripper to obtain stable output force of the gripper. Compared with symmetrical microgrippers, asymmetrical microgrippers usually have smaller output displacements. In order to increase the output displacement, a compliant mechanism with four stage amplification is employed to design the asymmetric microgripper. Consequently, the proposed asymmetrical microgripper possesses the advantages of both the stable output force of the gripper and large displacement amplification. To begin with, the mechanical model of the microgripper is established in this paper. The relationship between the driving force and the output displacement of the microgripper is then derived, followed by the static characteristics’ analysis of the microgripper. Furthermore, finite element analysis (FEA) of the microgripper is also performed, and the mechanical structure of the microgripper is optimized based on the FEA simulations. Lastly, experimental tests are carried out, with a 5.28% difference from the FEA results and an 8.8% difference from the theoretical results. The results from theoretical calculation, FEA simulations, and experimental tests verify that the displacement amplification ratio and the maximum gripping displacement of the microgripper are up to 31.6 and 632 μm, respectively.

Constant Force Compliant Mechanisms Without Preloading

2021 ◽  
Author(s):  
Premkumar Pujali ◽  
Hong Zhou
Keyword(s):  
Compliant Mechanisms ◽  
Large Range ◽  
Compliant Mechanism ◽  
Experimental Results ◽  
Design Parameters ◽  
Constant Force ◽  
Spline Curves ◽  
Output Force

Abstract A constant force compliant mechanism generates an output force that keeps invariant in a large range of input displacement. Because of the constant force feature and the merits of compliant mechanisms, they are utilized in many applications. A problem in the current constant force compliant mechanisms is their preloading range that is a certain starting range of the input displacement. In the preloading displacement, the output force of a constant force compliant mechanism does not have the desired value. It goes up from zero value. The preloading displacement often occupies one quarter or more of the entire input displacement range, which weakens the performance of constant force compliant mechanisms. The preloading issue is eradicated in this research by using prebuckled beams as components for constructing constant force compliant mechanisms. It is difficult to synthesize constant force compliant mechanisms that are composed of prebuckled beams because of the intertwined force, buckling and deflection characteristics. In this research, the undeformed beams are represented by spline curves and controlled by its interpolation points. The synthesis of constant force compliant mechanisms is systemized as optimizing the design parameters of the composed prebuckled beams. Fully compliant constant force compliant mechanisms are synthesized without preloading. The synthesis solutions are validated by experimental results.

Design and Evaluation of Compliant Constant-Force Mechanisms

1996 ◽  
Author(s):  
Alisa J. Millar ◽  
Larry L. Howell ◽  
James N. Leonard
Keyword(s):  
Strain Energy ◽  
Experimental Validation ◽  
Large Range ◽  
Constant Force ◽  
Dimensional Synthesis ◽  
Output Force ◽  
Simplified Method ◽  
Constant Output ◽  
Force Mechanism ◽  
Constant Force Mechanism

Abstract Compliant constant-force mechanisms combine the effects of mechanical advantage and stored strain energy of flexible members to obtain constant output forces for a large range of input displacements. This paper extends and compliments previous work by accomplishing the following: i) dimensional synthesis is performed for a number of compliant constant-force mechanism configurations, ii) a simplified method of determining the magnitude of the constant output force is presented, and iii) experimental validation of the theory is addressed by reporting the results of testing three constant-force configurations. The results of i) and ii) are presented in a manner to be easily used by engineers designing such mechanisms. The results of iii) show that the mechanisms do follow a nearly constant force for a large input displacement, as predicted.

Design and testing of an enhanced shape memory actuator elastically compensated by a bistable rocker arm

2012 ◽  
Vol 24 (6) ◽  
pp. 704-716 ◽  
Author(s):  
Giovanni Scirè Mammano ◽  
Eugenio Dragoni
Keyword(s):  
Fatigue Life ◽  
Shape Memory Alloy ◽  
Shape Memory ◽  
Experimental Testing ◽  
Test Results ◽  
Shape Memory Alloy Actuator ◽  
Output Force ◽  
Theoretical Predictions ◽  
Constant Output ◽  
Design And Testing

This article presents the design, the prototype construction, and the experimental testing of a shape memory actuator implementing the concept of elastic compensation put forward in a previous publication by the authors. A two-shape memory alloy actuator, compensated by a spring-assisted bistable rocker arm, is designed theoretically to provide nearly constant output forces and then it is built and characterized experimentally under laboratory conditions. The test results closely agree with the theoretical predictions and show that for given output force, the compensated actuator produces net strokes from 2.5 to 22 times greater than a twin uncompensated actuator. The stroke improvement increases dramatically with the generated output force. Weaknesses of the compensated design are the heavier average stress sustained by the shape memory alloy springs, which could impair the fatigue life, and a higher response time.

Design of Constant-Force Mechanisms Based on Straight-Line Linkages

2018 ◽  
Author(s):  
Hsin-Ting Huang ◽  
Chin-Hsing Kuo
Keyword(s):  
Mechanical Systems ◽  
Constant Force ◽  
Straight Line ◽  
Compression Spring ◽  
Output Force ◽  
Spring Type ◽  
Constant Output ◽  
Type C ◽  
Compression Springs ◽  
Complex Mechanical Systems

This paper presents two novel constant-force mechanisms (CFMs) based on Scott-Russell and Hart’s straight-line linkages with mechanical springs. By articulating either two compression springs (type C-C) or one compression spring with another one extension spring (type C-E) onto each of these two CFMs, the point(s) which trace straight-line trajectories can illustrate a constant force within the mechanism workspace. We also show that the preload of the extension spring for type C-E CFMs will not affect its constant-force property but can define the amount of the output force. The proposed concepts of CFMs are relatively simple and concise, which could be useful for the complex mechanical systems that request a constant output force. A constant-force robotic gripper is illustrated by using the proposed Scott-Russell-type CFM.

Study on a giant magnetostrictive actuator with constant output force

2013 ◽  
Vol 13 (2) ◽  
pp. 197 ◽  
Author(s):  
Hui Fang Liu ◽  
Zhen Yuan Jia ◽  
Fu Ji Wang ◽  
Fu cai Zong
Keyword(s):  
Output Force ◽  
Constant Output ◽  
Magnetostrictive Actuator

Design and Testing of an Enhanced Shape Memory Actuator Elastically Compensated by a Bi-Stable Rocker-Arm

2011 ◽  
Author(s):  
Giovanni Scire` Mammano ◽  
Eugenio Dragoni
Keyword(s):  
Fatigue Life ◽  
Shape Memory ◽  
Experimental Testing ◽  
Test Results ◽  
Output Force ◽  
Theoretical Predictions ◽  
Constant Output ◽  
Sma Actuator ◽  
Design And Testing ◽  
Good Agreement

This paper presents the design, the prototype construction and the experimental testing of a shape memory actuator implementing the concept of elastic compensation put forward in a previous publication by the authors. A two-SMA actuator, compensated by a spring-assisted bistable rocker-arm, is designed theoretically to provide nearly-constant output forces, then it is built and characterized under laboratory conditions. The test results are in good agreement with the theoretical predictions and show that, for given output force, the compensated actuator produces net strokes from 2.5 to 22 times greater than an identical uncompensated actuator. The stroke improvement increases dramatically with the generated output force. Weaknesses of the compensated design are the heavier average stress sustained by the SMA springs, which could impair the fatigue life, and a higher response time.

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