A Two Degree of Freedom Nanopositioner With Electrothermal Actuator for Decoupled Motion

2011 ◽  
Author(s):  
Yong-Sik Kim ◽  
Nicholas G. Dagalakis ◽  
Satyandra K. Gupta
Keyword(s):  
Design Concept ◽  
Degree Of Freedom ◽  
Motion Platform ◽  
Element Analysis ◽  
Electrothermal Actuators ◽  
Electrothermal Actuator ◽  
Decoupled Motion ◽  
Moving Platform ◽  
Two Degree Of Freedom ◽  
Novel Design

Building a two degree-of-freedom (2 DOF) MEMS nanopositioner with decoupled X-Y motion has been a challenge in nanopositioner design. In this paper a novel design concept on making the decoupled motion of the MEMS nanopositioner is suggested. The suggested nanopositioner has two electrothermal actuators and employs a fully nested motion platform with suspended anchors. The suggested MEMS nanopositioner is capable of delivering displacement from the electrothermal actuator to the motion platform without coupled motion between the two X-Y axes. The design concept, finite element analysis (FEA) results, fabrication procedures and the performance of the 2 DOF nanopositioner is presented. In order to test the nanopositioner moving platform decoupled motion, one actuator moves the platform by 60 μm, while the other actuator is kept at the same position. The platform position cross talk error was measured to be less than 1 μm standard deviation.

Dynamics of a Two-DOF Parallel Pointing Mechanism

2005 ◽  
Author(s):  
Alessandro Cammarata ◽  
Rosario Sinatra
Keyword(s):  
Numerical Simulation ◽  
Parallel Mechanism ◽  
Inverse Dynamics ◽  
Kinematic Model ◽  
Degree Of Freedom ◽  
Numerical Examples ◽  
Proposed Model ◽  
Dynamic Analyses ◽  
Moving Platform ◽  
Two Degree Of Freedom

This paper presents kinematic and dynamic analyses of a two-degree-of-freedom pointing parallel mechanism. The mechanism consists of a moving platform, connected to a fixed platform by two legs of type PUS (prismatic-universal-spherical). At first a simplified kinematic model of the pointing mechanism is introduced. Based on this proposed model, the dynamics equations of the system using the Natural Orthogonal Complement method are developed. Numerical examples of the inverse dynamics results are presented by numerical simulation.

scholarly journals Response of a Two-Degree-of-Freedom Vibration System with Rough Contact Interfaces

2019 ◽  
Vol 2019 ◽  
pp. 1-13
Author(s):  
Zhiqiang Huang ◽  
Xun Peng ◽  
Gang Li ◽  
Lei Hao
Keyword(s):  
Natural Frequency ◽  
Degree Of Freedom ◽  
Element Analysis ◽  
Chaotic Motions ◽  
First Order ◽  
Vibration Properties ◽  
Ground System ◽  
Jump Frequencies ◽  
Two Degree Of Freedom ◽  
Seismic Vibrator

This paper is focused on the influence of the rough contact interfaces on the dynamics of a coupled mechanical system. For this purpose, a two-degree-of-freedom model of a coupled seismic-vibrator-rough-ground system is proposed with which the nonlinear vibration properties are analyzed. In this model, the force-deflection characteristic of the contact interfaces is determined by finite element analysis. By analyzing the undamped free vibration, it was found that the variation of the second-order natural frequency with amplitude increases with rougher contact interfaces; however, the amplitude has little influence on the first-order natural frequency of the system. For the harmonic excited analysis, the jump frequencies and hysteretic region both decrease with rougher contact interfaces. Moreover, it is inferred from the bifurcation diagrams that, increasing the excitation force, the system can bring about chaotic motions on rough contact interfaces.

scholarly journals Design of a Planar Cable-Driven Parallel Crane Without Parasitic Tilt

2021 ◽  
Author(s):  
Lionel Etienne ◽  
Philippe Cardou ◽  
Marceau Métillon ◽  
Stéphane Caro
Keyword(s):  
Total Mass ◽  
Parallel Robots ◽  
Degree Of Freedom ◽  
Mobile Platform ◽  
Moving Platform ◽  
High Dynamics ◽  
Two Degree Of Freedom ◽  
High Payload

Abstract Cable-Driven Parallel Robots (CDPRs) offer high payload capacities, large translational workspace and high dynamics performances. Their rotational workspace is generally far more limited, however, which can be resolved by using cable loops, as was shown in previous research. In the case of fully-constrained CDPRs, cable loops can induce unwanted torques on the moving-platform, causing it to tilt and move away from its intended position, which we call parasitic tilt. Hence, the orientation accuracy of such robots is usually limited. This paper deals with the design, modelling and prototyping of a planar CDPR with infinite rotations, without parasitic tilt and without an additional motor. This robot, which we call a Cable-Driven Parallel Crane (CDPC), is composed of a mobile platform (MP) with an embedded mechanism and a transmission module. The MP is linked with the frame by a parallelogram of three cables to constrain its orientation, including a cable loop, as well as a fourth cable. The two-degree-of-freedom (dof) motions of the moving-platform of the CDPC and the internal dof of its embedded mechanism are actuated by a total of three actuators, which are fixed to the frame. As a consequence, the overall system is fully-actuated, its total mass and inertia in motion is reduced and it is free of parasitic tilts.

Novel Design Method for Two Degree of Freedom Controllers

2015 ◽  
Vol 8 (4) ◽  
pp. 281 ◽  
Author(s):  
P. Febina Beevi ◽  
T. K. Sunil Kumar ◽  
Jeevamma Jacob
Keyword(s):  
Design Method ◽  
Degree Of Freedom ◽  
Two Degree Of Freedom ◽  
Novel Design

Analysis and Design of a Two Degree of Freedom Hoeckens-Pantograph Leg Mechanism

2015 ◽  
Author(s):  
Dmitri Fedorov ◽  
Lionel Birglen
Keyword(s):  
Screw Theory ◽  
Degree Of Freedom ◽  
Performance Indices ◽  
Single Degree Of Freedom ◽  
Analysis And Design ◽  
Single Degree ◽  
Compliant Joints ◽  
Two Degree Of Freedom ◽  
Novel Design ◽  
Limited Motion

Hoeckens and Chebychev linkages have been widely discussed in the literature as design solutions to build single degree of freedom (DOF) leg mechanisms. Compared to fully actuated legs, often bio-inspired, they offer an unmatched simplicity. However, due to their limited motion capability, they can only be used when the traversed terrain is of limited difficulty. In order to alleviate this drawback, a novel design with a second DOF is proposed in this paper. The introduced mechanism is composed of a Hoeckens linkage augmented by a Pantograph for which the position of the pivot can be changed through an additional rotating link. Screw theory is used to determine the kinematic equations of the mechanism, its singular configurations, and its attainable workspace. Subsequently, an optimization of the geometric parameters is performed to maximize performance indices pertaining to the size of the mechanism’s workspace. Finally, possible use of compliant joints is discussed.

scholarly journals Motion Control of a Two-Degree-of-Freedom Linear Resonant Actuator without a Mechanical Spring

Sensors ◽  
2020 ◽  
Vol 20 (7) ◽  
pp. 1954
Author(s):  
Gyunam Kim ◽  
Katsuhiro Hirata
Keyword(s):  
Motion Control ◽  
Control Method ◽  
Design Method ◽  
Degree Of Freedom ◽  
Position Sensor ◽  
Motion Controller ◽  
Element Analysis ◽  
Mechanical Spring ◽  
Elliptical Motion ◽  
Two Degree Of Freedom

This study aims to present a new two-degree-of-freedom (DOF) linear resonant actuator (LRA) and its motion control method without a position sensor. The design method of 2-DOF LRA which resonates with only detent force without a mechanical spring is proposed. Since the information of displacement and direction is required to control 2-DOF LRA, a sensor or an estimator is needed. Therefore, we proposed a position estimator and a motion controller for 2-DOF LRA. This paper proved that reciprocating motion, elliptical motion, and scrolling motion can be controlled without a position sensor. Finite element analysis (FEA) and dynamic simulation results validated the proposed method as well.

Design and Development of a Two Degree-of-Freedom Rotational Flexure Mechanism for Precise Unbalance Measurements

2017 ◽  
Vol 9 (4) ◽  
Author(s):  
Zhao Hongzhe ◽  
Ren Siyuan ◽  
Li Ming ◽  
Zhang Shuqing
Keyword(s):  
Calibration Procedure ◽  
Degree Of Freedom ◽  
Load Carrying Capacity ◽  
Shape Parameters ◽  
Rotational Stiffness ◽  
Element Analysis ◽  
Flexure Mechanism ◽  
Leaf Springs ◽  
Load Carrying ◽  
Two Degree Of Freedom

To measure unbalanced moments, the knife-edge is used as a support module in traditional platforms, but performances rapidly deteriorate as the edge is worn down. In this paper, considering the requirements of measurements, a two degree-of-freedom (DOF) flexure mechanism is, thus, presented to overcome this drawback. First, off-axis stiffness and manufacturability are improved qualitatively by means of configuration analysis. Then, four generalized cross-spring pivots are exploited in the 2DOF flexure mechanism, and the geometric parameters are analyzed to achieve approximately constant rotational stiffness and reduced center shift simultaneously, which benefits calibration procedure and measurement precision. Models are further developed to determine the shape parameters of leaf-springs and transducer performances. Therefore, a low rotational stiffness is obtained to ensure a high resolution for measurements, and a high load-carrying capacity is achieved via strength checking. Finally, finite element analysis (FEA) is carried out to validate the proposed design, and experimental results demonstrate that the developed platform is capable of unbalance measurements with a high precision and resolution.

scholarly journals Passive Prosthetic Foot Shape and Size Optimization Using Lower Leg Trajectory Error

2017 ◽  
Author(s):  
Kathryn M. Olesnavage ◽  
Amos G. Winter
Keyword(s):  
Optimal Design ◽  
Compliant Mechanism ◽  
Lower Leg ◽  
Degree Of Freedom ◽  
Analytical Models ◽  
Element Analysis ◽  
Trajectory Error ◽  
Prosthetic Foot ◽  
Two Degree Of Freedom ◽  
Shape And Size

A method is presented to optimize the shape and size of a passive prosthetic foot using the Lower Leg Trajectory Error (LLTE) as the design objective. The LLTE is defined as the root-mean-square error between the lower leg trajectory calculated for a given prosthetic foot by finding the deformed shape of the foot under typical ground reaction forces and a target physiological lower leg trajectory obtained from published gait data for able-bodied walking. In previous work, the design of simple two degree-of-freedom analytical models consisting of rigid structures, rotational joints with constant stiffness, and uniform cantilevered beams, have been optimized for LLTE. However, prototypes built to replicate these simple models were large, heavy, and overly complex. In this work, the size and shape of a single-part compliant prosthetic foot keel made out of nylon 6/6 was optimized for LLTE to produce a light weight, low cost, and easily manufacturable prosthetic foot design. The shape of the keel was parameterized as a wide Bézier curve, with constraints ensuring that only physically meaningful shapes were considered. The LLTE value for each design was evaluated using a custom MATLAB script, which ran ADINA finite element analysis software to find the deformed shape of the prosthetic keel under multiple loading scenarios. The optimization was performed by MATLAB’s built-in genetic algorithm. After the optimal design for the keel was found, a heel was added to structure, sized such that when the user’s full weight acted on the heel, the structure had a factor of safety of two. The resulting optimal design has a lower LLTE value than the two degree-of-freedom analytical models, at 0.154 compared to 0.172, 0.187, and 0.269 for the two degree-of-freedom models. At 412 g, the optimal wide curve foot is nearly half the mass of the lightest prototype built from the previous models, which was 980 g. The design found through this compliant mechanism optimization method is thus far superior to the two degree-of-freedom models previously considered.

Sign in / Sign up

Export Citation Format

Share Document