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.

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.

Dimensional Synthesis of Compliant Constant-Force Slider Mechanisms

1994 ◽  
Author(s):  
Larry L. Howell ◽  
Ashok Midha ◽  
Morgan D. Murphy
Keyword(s):  
Compliant Mechanisms ◽  
Design Procedure ◽  
Constant Force ◽  
Dimensional Synthesis ◽  
Model Concept ◽  
Output Force ◽  
Rigid Body Model ◽  
Constant Output ◽  
Force Mechanism ◽  
Constant Force Mechanism

Abstract Constant-force mechanisms produce a constant output force for a range of input displacements. Such mechanisms are important in applications with a varying displacement but a constant resultant force required. Constant-force mechanism designs have been limited to rigid-link mechanisms, but the design of compliant, or flexible link, constant force mechanisms could increase the number of applications by taking advantage of the unique characteristics of compliant mechanisms. Murphy (1993) developed type-synthesis theories for compliant mechanisms and applied them to generate possible configurations for compliant constant-force slider mechanisms. This paper concentrates on the dimensional synthesis of several of the resulting topologies. Optimization and the pseudo-rigid-body-model concept are employed in the design procedure. An example application as an electrical connection for use in electronic chip carriers is also illustrated.

A Load-Adjustable Constant-Force Mechanism

2018 ◽  
Author(s):  
Steven Hasara ◽  
Craig Lusk
Keyword(s):  
Reaction Force ◽  
Longitudinal Axis ◽  
Degree Of Freedom ◽  
Constant Force ◽  
Force Output ◽  
Constant Output ◽  
Force Mechanism ◽  
Constant Force Mechanism ◽  
Novel Design ◽  
Second Degree

This paper outlines the design of a compliant crank slider with adjustable constant-force output. Constant-force mechanisms (CFM) are used to maintain a constant output reaction force throughout a large range of compressive motion. This novel design improves on existing CFM by introducing a second degree of freedom that adjusts the mechanism’s output without changing its kinematic structure. This second degree of freedom is the rotation of a compliant beam about its longitudinal axis as it is constrained to the initial plane of bending. The resulting change in the beam’s stiffness allows for adjustment to a specifiable range of constant-force outputs.

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.

scholarly journals An Output Force Control for Robotic Manipulator by Changing the Spring Stiffness

2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Jirong Wang ◽  
Yuhang Zheng ◽  
Jun Li ◽  
Cheng Liu ◽  
Youliang Huang ◽  
...  
Keyword(s):  
Rigid Body ◽  
Nonlinear Stiffness ◽  
Constant Force ◽  
Spring Stiffness ◽  
Linkage Mechanism ◽  
Modeling And Analysis ◽  
Output Force ◽  
Stiffness Characteristics ◽  
Force Mechanism ◽  
Improved Design

This paper presents an output control for a manipulator by changing the spring stiffness. Through the modeling and analysis of the nonlinear stiffness characteristics of the crank-rocker mechanism, and using the zero stiffness domain search method to select the appropriate spring stiffness, using different spring stiffness to establish different mechanism models, the robot can finally control the output of ideal constant force, and at the same time, the analysis results are applied to the improved design of the tire grabbing manipulator. Through this method, the tire grabbing manipulator becomes a constant grabbing force mechanism, and the mechanism is transformed from a rigid-body mechanism to a pseudo-rigid-body mechanism. The accuracy and stability of the whole system are greatly improved. In this study, the method of adding spring to each joint of the linkage mechanism is applied to the improvement design of the linkage mechanism, and the four-bar constant force mechanism is designed for the first time, which expands the application field of the nonlinear stiffness characteristics of the linkage mechanism, and has great application value to the improvement design of the mechanical system with the linkage mechanism and the control of the output force.

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.

scholarly journals Design, Analysis and Experimental Eerification of a Epatial Constant Force End-Effector for Polishing/Deburring Operations

2021 ◽  
Author(s):  
Bingxiao Ding ◽  
Jixu Zhao ◽  
Yangmin Li
Keyword(s):  
Experimental Studies ◽  
Experimental Tests ◽  
Constant Force ◽  
Element Analysis ◽  
Design Concepts ◽  
Force Variation ◽  
Fea Simulation ◽  
Force Mechanism ◽  
And Control ◽  
The Mathematical Model

Abstract Controlling the contact force on workpieces is a challenging task for industrial deburring operations. To solve this issue, a novel constant force mechanism(CFM) based on the combination of positive and negative sti ness mechanism is proposed by using folding beam and bi-stable beam. Without using any additional sensors and control algorithms, the proposed mechanism can produce a travel range in constant force manner. In this paper, the design concepts, analytical modeling, finite element analysis (FEA) simulation and experimental studies are presented and discussed. Firstly, a novel spatial CFM is proposed and using the pseudo rigid body(PRB) to established the mathematical model of the whole mechanism. Then, the FEA simulation is performed to validate the correctness of theoretical analysis. In addition, to eliminate the force variation, particle swarm optimization (PSO) method is utilized to find optimal architectural parameters solutions of the CFM. Finally, the experimental tests are performed to verify the performance of the designed CFM. The confguration design and parameter optimization can be further applied to the design of other CFM mechanisms for polishing operations.

Urbanicity, City Delegations, and Two-Dimensional Liberalism

2018 ◽  
Author(s):  
Thomas K. Ogorzalek
Keyword(s):  
National Level ◽  
Two Dimensions ◽  
Political Order ◽  
Two Dimensional ◽  
Local Institutions ◽  
Horizontal Integration ◽  
National Politics ◽  
United Front ◽  
Strategies For Success

This theoretical chapter develops the argument that the conditions of cities—large, densely populated, heterogeneous communities—generate distinctive governance demands supporting (1) market interventions and (2) group pluralism. Together, these positions constitute the two dimensions of progressive liberalism. Because of the nature of federalism, such policies are often best pursued at higher levels of government, which means that cities must present a united front in support of city-friendly politics. Such unity is far from assured on the national level, however, because of deep divisions between and within cities that undermine cohesive representation. Strategies for success are enhanced by local institutions of horizontal integration developed to address the governance demands of urbanicity, the effects of which are felt both locally and nationally in the development of cohesive city delegations and a unified urban political order capable of contending with other interests and geographical constituencies in national politics.

Sign in / Sign up

Export Citation Format

Share Document