An XYZ Parallel-Kinematic Flexure Mechanism With Geometrically Decoupled Degrees of Freedom

2012 ◽  
Vol 5 (1) ◽  
Author(s):  
Shorya Awtar ◽  
John Ustick ◽  
Shiladitya Sen
Keyword(s):  
Degrees Of Freedom ◽  
Finite Elements Analysis ◽  
Motion Direction ◽  
Flexure Mechanism ◽  
Nonlinear Finite Elements ◽  
Decoupled Motion ◽  
Motion Range ◽  
Stiffness Variation ◽  
Parallel Kinematic ◽  
Cross Axis

A novel parallel-kinematic flexure mechanism that provides highly decoupled motions along the three translational directions (X, Y, and Z) and high stiffness along the three rotational directions (θx, θy, and θz) is presented. Geometric decoupling ensures large motion range along each translational direction and enables integration with large-stroke ground-mounted linear actuators or generators, depending on the application. The proposed design, which is based on a systematic arrangement of multiple rigid stages and parallelogram flexure modules, is analyzed via nonlinear finite elements analysis (FEA). A proof-of-concept prototype is fabricated to validate the predicted large range and decoupled motion capabilities. The analysis and the hardware prototype demonstrate an XYZ motion range of 10 mm × 10 mm × 10 mm. Over this motion range, the nonlinear FEA predicts cross-axis errors of less than 7.8%, parasitic rotations less than 10.8 mrad, less than 14.4% lost motion, actuator isolation better than 1.5%, and no perceptible motion direction stiffness variation.

An XYZ Parallel Kinematic Flexure Mechanism With Geometrically Decoupled Degrees of Freedom

2011 ◽  
Author(s):  
Shorya Awtar ◽  
John Ustick ◽  
Shiladitya Sen
Keyword(s):  
Degrees Of Freedom ◽  
Element Analysis ◽  
Motion Direction ◽  
Form Analysis ◽  
Flexure Mechanism ◽  
Non Linear ◽  
Decoupled Motion ◽  
Motion Range ◽  
Parallel Kinematic ◽  
Cross Axis

We present the constraint-based design of a novel parallel kinematic flexure mechanism that provides highly decoupled motions along the three translational directions (X, Y, and Z) and high stiffness along the three rotational directions (θx, θy, and θz). The geometric decoupling ensures large motion range along each translational direction and enables integration with large-stroke ground-mounted linear actuators or generators, depending on the application. The proposed design, which is based on a systematic arrangement of multiple rigid stages and parallelogram flexure modules, is analyzed via non-linear finite element analysis. A proof-of-concept prototype of the flexure mechanism is fabricated to validate its large range and decoupled motion capability. The analyses as well as the hardware demonstrate an XYZ motion range of 10 mm × 10 mm × 10 mm. Over this motion range, the non-linear FEA predicts a cross-axis error of less than 3%, parasitic rotations less than 2 mrad, less than 4% lost motion, actuator isolation less than 1.5%, and no perceptible motion direction stiffness variation. Ongoing work includes non-linear closed-form analysis and experimental measurement of these error motion and stiffness characteristics.

Experimental Characterization of a Large-Range Parallel Kinematic XYZ Flexure Mechanism

2020 ◽  
Vol 13 (1) ◽  
Author(s):  
Shorya Awtar ◽  
Jason Quint ◽  
John Ustick
Keyword(s):  
Degrees Of Freedom ◽  
Large Range ◽  
Experimental Setup ◽  
Modular Construction ◽  
Finite Elements Analysis ◽  
Motion Direction ◽  
Flexure Mechanism ◽  
Parallel Kinematic ◽  
Cross Axis ◽  
Exact Constraint

Abstract Previously, we reported the conceptual design of a novel parallel-kinematic flexure mechanism that provides large and decoupled motions in the X, Y, and Z directions, along with good actuator isolation, and small parasitic error motions (Awtar, S., Ustick, J., and Sen, S., 2012, “An XYZ Parallel-Kinematic Flexure Mechanism With Geometrically Decoupled Degrees of Freedom,” ASME J. Mech. Rob., 5(1), p. 015001). This paper presents the detailed design and fabrication of a high-precision experimental setup to characterize and validate the motion attributes of this proposed flexure design via comprehensive measurements. The unique aspects of this experimental setup include a novel modular construction and exact-constraint assembly of the flexure mechanism from 12 identical parallelogram flexure modules. The flexure mechanism along with the sensing and actuation setup in the experiment is designed to enable large range (10 mm) in each direction. Experimental measurements and finite-elements analysis demonstrate <3% variation in motion direction stiffness, 20.4% lost motion, <11.6% cross-axis error, <3.3% actuator isolation, and <9.5 mrad motion stage rotation over the entire 10 mm × 10 mm × 10 mm range of motion.

Characteristics of Beam-Based Flexure Modules

2006 ◽  
Vol 129 (6) ◽  
pp. 625-639 ◽  
Author(s):  
Shorya Awtar ◽  
Alexander H. Slocum ◽  
Edip Sevincer
Keyword(s):  
Finite Element Analysis ◽  
Analytical Framework ◽  
Equilibrium Conditions ◽  
Element Analysis ◽  
Flexure Mechanism ◽  
Important Constraint ◽  
Motion Range ◽  
Stiffness Variation ◽  
Force Displacement ◽  
Force Equilibrium

The beam flexure is an important constraint element in flexure mechanism design. Nonlinearities arising from the force equilibrium conditions in a beam significantly affect its properties as a constraint element. Consequently, beam-based flexure mechanisms suffer from performance tradeoffs in terms of motion range, accuracy and stiffness, while benefiting from elastic averaging. This paper presents simple yet accurate approximations that capture the effects of load-stiffening and elastokinematic nonlinearities in beams. A general analytical framework is developed that enables a designer to parametrically predict the performance characteristics such as mobility, over-constraint, stiffness variation, and error motions, of beam-based flexure mechanisms without resorting to tedious numerical or computational methods. To illustrate their effectiveness, these approximations and analysis approach are used in deriving the force–displacement relationships of several important beam-based flexure constraint modules, and the results are validated using finite element analysis. Effects of variations in shape and geometry are also analytically quantified.

Design of a Large Range XY Nanopositioning System

2010 ◽  
Author(s):  
Shorya Awtar ◽  
Gaurav Parmar
Keyword(s):  
Physical System ◽  
Large Range ◽  
Test Results ◽  
Flexure Mechanism ◽  
Motion Range ◽  
Parallel Kinematic ◽  
Large Motion ◽  
The Individual ◽  
High Degree ◽  
Motion Quality

Achieving large motion range (> 1 mm) along with nanometric motion quality (< 10 nm), simultaneously, has been a key challenge in nanopositioning systems. Practical limitations associated with the individual physical components (flexure bearing, actuators, and sensors) and their integration, particularly in the case of multi-axis systems, have restricted the range of current nanopositioning systems to about 100 μm. This paper presents a novel physical system layout, with a parallel-kinematic XY flexure mechanism at its heart, that provides a high degree of decoupling between the two motion axes by avoiding geometric over-constraints, provides actuator isolation that allows the use of large-stroke single-axis actuators, and enables a complementary end-point sensing scheme that employs commonly available sensors. These attributes help achieve an unprecedented 10 mm × 10 mm motion range in the proposed nanopositioning system. Having overcome the physical system design challenges, a dynamic model of proposed nanopositioning system is created and verified via system identification methods. In particular, dynamic non-linearities associated with the large displacements of the flexure mechanism and resulting controls challenges are identified. The physical system is fabricated, assembled, and tested to validate its simultaneous large range and nanometric motion capabilities. Preliminary closed-loop test results, which highlight the potential of this new design configuration, are presented.

Design and analysis of a novel large-range 3-DOF compliant parallel micromanipulator

2021 ◽  
Vol 13 (12) ◽  
pp. 168781402110344
Author(s):  
Jinhai Gao ◽  
Xiaoqiang Han ◽  
Lina Hao ◽  
Ligang Chen
Keyword(s):  
Integrated Circuit ◽  
Degrees Of Freedom ◽  
Large Range ◽  
Topology Design ◽  
Spatial Density ◽  
Integrated Circuit Fabrication ◽  
Circuit Fabrication ◽  
Motion Range ◽  
Large Motion ◽  
Cross Axis

Compared with the traditional rigid mechanism, the flexible mechanism has more advantages, which play an important role in critical situations such as microsurgery, IC (integrated circuit) fabrication/detection, and some precision operating environment. Especially, there is an increasing need for 3-DOF (degrees-of-freedom) compliant translational micro-platform (CTMP) providing good performance characteristics with large motion range, low cross coupling, and high spatial density. Decoupled topology design of the CTMP can easily realize these merits without increasing the difficulty of controlling. This paper proposes a new three DOF compliant hybrid micromanipulator which have large range of motion up to 100 μm × 100 μm × 100 μm in the direction in the dimension of 90 mm × 90 mm × 50 mm, smaller cross-axis coupling (the max coupling only 2.5%) than the initial XY compliant platform in XY axial.

A Generalized Constraint Model for Two-Dimensional Beam Flexures: Nonlinear Load-Displacement Formulation

2010 ◽  
Vol 132 (8) ◽  
Author(s):  
Shorya Awtar ◽  
Shiladitya Sen
Keyword(s):  
Two Dimensional ◽  
Finite Elements Analysis ◽  
Nonlinear Load ◽  
Beam Shape ◽  
Flexure Mechanism ◽  
Elastic Load ◽  
Nonlinear Finite Elements ◽  
Wide Range ◽  
Load Displacement ◽  
Constraint Model

To utilize beam flexures in constraint-based flexure mechanism design, it is important to develop qualitative and quantitative understanding of their constraint characteristics in terms of stiffness and error motions. This paper provides a highly generalized yet accurate closed-form parametric load-displacement model for two-dimensional beam flexures, taking into account the nonlinearities arising from load equilibrium applied in the deformed configuration. In particular, stiffness and error motions are parametrically quantified in terms of elastic, load-stiffening, kinematic, and elastokinematic effects. The proposed beam constraint model incorporates a wide range of loading conditions, boundary conditions, initial curvature, and beam shape. The accuracy and effectiveness of the proposed beam constraint model is verified by nonlinear finite elements analysis.

Design of a Large Range XY Nanopositioning System

2013 ◽  
Vol 5 (2) ◽  
Author(s):  
Shorya Awtar ◽  
Gaurav Parmar
Keyword(s):  
Physical System ◽  
Large Range ◽  
Test Results ◽  
Flexure Mechanism ◽  
Motion Range ◽  
Parallel Kinematic ◽  
Large Motion ◽  
The Individual ◽  
High Degree ◽  
Motion Quality

Achieving large motion range (>1 mm) along with nanometric motion quality (<10 nm) simultaneously has been a key challenge in nanopositioning systems. Practical limitations associated with the individual physical components (bearing, actuators, and sensors) and their integration, particularly in the case of multi-axis systems, have restricted the range of currently available nanopositioning systems to approximately 100 μm per axis. This paper presents a novel physical system layout, comprising a bearing, actuators, and sensors, that enables large range XY nanopositioning. The bearing is based on a parallel-kinematic XY flexure mechanism that provides a high degree of geometric decoupling between the two motion axes by avoiding geometric over-constraint, provides actuator isolation that allows the use of large-stroke single-axis actuators, and enables a complementary end-point sensing scheme using commonly available sensors. These attributes help achieve 10 mm × 10 mm motion range in the proposed nanopositioning system. Having overcome the physical system design challenges, a dynamic model of the proposed nanopositioning system is created and verified via system identification. In particular, dynamic nonlinearities associated with the large displacements of the flexure mechanism and resulting controls challenges are identified. The physical system is fabricated, assembled, and tested to validate its simultaneous large range and nanometric motion capabilities. Preliminary closed-loop test results, which highlight the potential as well as pending challenges associated with this new design configuration, are presented.

Constraint-Based Design of Parallel Kinematic XY Flexure Mechanisms

2006 ◽  
Vol 129 (8) ◽  
pp. 816-830 ◽  
Author(s):  
Shorya Awtar ◽  
Alexander H. Slocum
Keyword(s):  
Performance Characteristics ◽  
Element Analysis ◽  
Nonlinear Load ◽  
Flexure Mechanism ◽  
Nonlinear Force ◽  
Parallel Kinematic ◽  
Improved Performance ◽  
Design Tradeoffs ◽  
Cross Axis ◽  
Force Displacement

This paper presents parallel kinematic XY flexure mechanism designs based on systematic constraint patterns that allow large ranges of motion without causing over-constraint or significant error motions. Key performance characteristics of XY mechanisms such as mobility, cross-axis coupling, parasitic errors, actuator isolation, drive stiffness, lost motion, and geometric sensitivity, are discussed. The standard double parallelogram flexure module is used as a constraint building-block and its nonlinear force-displacement characteristics are employed in analytically predicting the performance characteristics of two proposed XY flexure mechanism designs. Fundamental performance tradeoffs, including those resulting from the nonlinear load-stiffening and elastokinematic effects, in flexure mechanisms are highlighted. Comparisons between closed-form linear and nonlinear analyses are presented to emphasize the inadequacy of the former. It is shown that geometric symmetry in the constraint arrangement relaxes some of the design tradeoffs, resulting in improved performance. The nonlinear analytical predictions are validated by means of computational finite element analysis and experimental measurements.

A two degrees of freedom comb capacitive-type accelerometer with low cross-axis sensitivity

2019 ◽  
Vol 13 (3) ◽  
pp. 5334-5346
Author(s):  
M. N. Nguyen ◽  
L. Q. Nguyen ◽  
H. M. Chu ◽  
H. N. Vu
Keyword(s):  
Degrees Of Freedom ◽  
Proof Mass ◽  
Vibration Modes ◽  
Electrode Structure ◽  
Element Analysis ◽  
Mechanical Coupling ◽  
Fully Differential ◽  
Mode Effects ◽  
The Finite Element Analysis ◽  
Cross Axis

In this paper, we report on a SOI-based comb capacitive-type accelerometer that senses acceleration in two lateral directions. The structure of the accelerometer was designed using a proof mass connected by four folded-beam springs, which are compliant to inertial displacement causing by attached acceleration in the two lateral directions. At the same time, the folded-beam springs enabled to suppress cross-talk causing by mechanical coupling from parasitic vibration modes. The differential capacitor sense structure was employed to eliminate common mode effects. The design of gap between comb fingers was also analyzed to find an optimally sensing comb electrode structure. The design of the accelerometer was carried out using the finite element analysis. The fabrication of the device was based on SOI-micromachining. The characteristics of the accelerometer have been investigated by a fully differential capacitive bridge interface using a sub-fF switched-capacitor integrator circuit. The sensitivities of the accelerometer in the two lateral directions were determined to be 6 and 5.5 fF/g, respectively. The cross-axis sensitivities of the accelerometer were less than 5%, which shows that the accelerometer can be used for measuring precisely acceleration in the two lateral directions. The accelerometer operates linearly in the range of investigated acceleration from 0 to 4g. The proposed accelerometer is expected for low-g applications.

CONSTRAINT-BASED ANALYSIS OF PARALLEL KINEMATIC ARTICULATED WRIST MECHANISM

2021 ◽  
pp. 1-11
Author(s):  
Revanth Damerla ◽  
Shorya Awtar
Keyword(s):  
Degrees Of Freedom ◽  
Systematic Analysis ◽  
Load Bearing ◽  
Load Transmission ◽  
Pure Rotation ◽  
Parallel Kinematic ◽  
Design Tradeoffs ◽  
Transmission Capability

Abstract This paper presents a systematic constraint-based analysis of the performance attributes of eight parallel kinematic articulated wrist mechanisms from the existing literature. These performance attributes include the number, nature (i.e. pure rotation, or translation, or a combination), and location of a mechanism's Degrees of Freedom (DoFs) in the nominal and displaced configurations, load transmission capability along these DoFs, and load bearing capability along the constraint directions. This systematic analysis reveals performance tradeoffs between these performance attributes for a given mechanism, as well as design tradeoffs across these mechanisms. This analysis also helps inform the suitability of a given mechanism for specific applications.

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