Cross Coupling in Parallel Kinematic MEMS Nanopositioners

2015 ◽  
Author(s):  
Mohammad Maroufi ◽  
S. O. Reza Moheimani
Keyword(s):  
Experimental Data ◽  
Analytical Model ◽  
Close Agreement ◽  
Cross Coupling ◽  
Experimental Results ◽  
Micro Fabrication ◽  
Parallel Kinematic Mechanism ◽  
Parallel Kinematic ◽  
The Cross ◽  
Kinematic Mechanism

In this paper we study the origins of the cross coupling phenomenon in MEMS nanopositioners with a parallel kinematic mechanism. An analytical model is provided for a generic 2-DOF MEMS nanopositioner. The model accounts for the potential mechanical asymmetries present in the device due to micro-fabrication imperfections. Simulations are performed based on the obtained model and compared with experimental data from a previously reported MEMS nanopositioner. A close agreement is observed between the analytical and experimental results, leading to a better understanding of the phenomenon.

Convective Losses From Cavity Solar Receivers—Comparisons Between Analytical Predictions and Experimental Results

1983 ◽  
Vol 105 (1) ◽  
pp. 29-33 ◽  
Author(s):  
A. M. Clausing
Keyword(s):  
Experimental Data ◽  
Experimental Evidence ◽  
Analytical Model ◽  
Excellent Agreement ◽  
Experimental Results ◽  
Simple Analytical Model ◽  
Refined Model ◽  
Wall Area

Cavity solar receivers are generally believed to have higher thermal efficiencies than external receivers due to reduced losses. A simple analytical model was presented by the author which indicated that the ability to heat the air inside the cavity often controls the convective loss from cavity receivers. Thus, if the receiver contains a large amount of inactive hot wall area, it can experience a large convective loss. Excellent experimental data from a variety of cavity configurations and orientations have recently become available. These data provided a means of testing and refining the analytical model. In this manuscript, a brief description of the refined model is presented. Emphasis is placed on using available experimental evidence to substantiate the hypothesized mechanisms and assumptions. Detailed comparisons are given between analytical predictions and experimental results. Excellent agreement is obtained, and the important mechanisms are more clearly delineated.

Kinematic Analysis of a Novel 3-DOF Parallel Mechanism with Actuation Redundancy

2013 ◽  
Vol 816-817 ◽  
pp. 821-824
Author(s):  
Xue Mei Niu ◽  
Guo Qin Gao ◽  
Zhi Da Bao
Keyword(s):  
Kinematic Analysis ◽  
Parallel Mechanism ◽  
Rbf Neural Network ◽  
Analysis Method ◽  
Parallel Kinematic Mechanism ◽  
Redundantly Actuated ◽  
Parallel Kinematic ◽  
Forward Kinematic ◽  
Kinematic Mechanism ◽  
Kinematic Solution

Kinematic analysis plays an important role in the research of parallel kinematic mechanism. This paper addresses a novel forward kinematic solution based on RBF neural network for a novel 2PRRR-PPRR redundantly actuated parallel mechanism. Simulation results illustrate the validity and feasibility of the kinematic analysis method.

Accuracy Synthesis of Redundant Parallel Kinematic Mechanism with Weighted Least Square Method

2012 ◽  
Vol 499 ◽  
pp. 3-8
Author(s):  
Xin You Li ◽  
Wu Yi Chen
Keyword(s):  
Machine Tool ◽  
Conventional Method ◽  
Least Square Method ◽  
Least Square ◽  
Tolerance Allocation ◽  
Manufacturing Processes ◽  
Manufacturing Cost ◽  
Parallel Kinematic Mechanism ◽  
Parallel Kinematic ◽  
Kinematic Mechanism

In order to reduce manufacturing cost, a methodology of accuracy synthesis for machine tool was recommended by combining both machining cost and Least Square method. Weighted coefficients representing the machining difficulty of manufacturing processes were introduced. 3PRS/UPS redundant parallel kinematic mechanism (3PRS/UPS PKM) was taken as an example, and its component tolerances were derived by the proposed method. Comparing with conventional method, the component tolerances were allocated reasonably. A further tolerance allocation for spherical and rotational joints was studied in detail. And hence, the producibility of component was improved and the manufacturing cost was reduced. The results showed that the proposed method was capable of producing tolerance allocations economically and accurately.

Soft pneumatic actuator-driven origami-inspired modular robotic “pneumagami”

2020 ◽  
pp. 027836492090990 ◽  
Author(s):  
Matthew A Robertson ◽  
Ozdemir Can Kara ◽  
Jamie Paik
Keyword(s):  
High Strength ◽  
Small Scale ◽  
Task Space ◽  
Pneumatic Actuators ◽  
Construction Methods ◽  
Parallel Kinematic Mechanism ◽  
Parallel Kinematic ◽  
Structural Mechanisms ◽  
High Degree ◽  
Kinematic Mechanism

This article presents a new modular robotic platform for enabling reconfigurable, actively controlled, high-degree-of-freedom (high-DoF) systems with compact form factor. The robotic modules exploit the advantages of origami-inspired construction methods and materials, and soft pneumatic actuators (SPAs) to achieve an actuator embedded, parallel kinematic mechanism with three independently controlled “waterbomb” base legs. The multi-material, layer-fabricated body of the modules features selectively compliant flexure hinge elements between rigid panels that define the module as a kinematic 6R spherical joint. The precision layer-fabrication technique is also used to form embedded distribution channels within the module base to connect actuators to onboard control hardware. A decentralized control architecture is applied by integrating each module with small-scale solenoid valves, communication electronics, and sensors. This design approach enables a single pneumatic supply line to be shared between modules, while still allowing independent control of each leg joint, driven by soft, inflatable pouch actuators. A passive pneumatic relay is also designed and incorporated in each module to leverage the coupled, inverted inflation, and exhaust states between antagonistic actuator pairs allowing both to be controlled by a single solenoid valve. A prototype module is presented as the first demonstration of integrated modular origami and SPA design, or pneumagami, which allows predefined kinematic structural mechanisms to locally prescribe specific motions by active effect, not just through passive compliance, to dictate task space and motion. The design strategy facilitates the composition of lightweight, high-strength robotic structures with many DoFs that will benefit various fields such as wearable robotics.

Complete kinematic calibration of a 6-RRRPRR parallel kinematic machine based on the optimal measurement configurations

2019 ◽  
Vol 234 (1) ◽  
pp. 121-136 ◽  
Author(s):  
Chunyang Han ◽  
Yang Yu ◽  
Zhenbang Xu ◽  
Xiaoming Wang ◽  
Peng Yu ◽  
...  
Keyword(s):  
Kinematic Model ◽  
Inverse Kinematic ◽  
Error Model ◽  
Kinematic Calibration ◽  
Universal Joint ◽  
Parallel Kinematic Mechanism ◽  
Simulation And Experiment ◽  
Parallel Kinematic ◽  
Kinematic Mechanism ◽  
Selection Of

This paper presents a kinematic calibration of a 6-RRRPRR parallel kinematic mechanism with offset RR-joints that would be applied in space positioning field. In order to ensure highly accurate and highly effective calibration process, the complete error model, which contains offset universal joint errors, is established by differentiating inverse kinematic model. A calibration simulation comparison with non-complete error model shows that offset universal joint errors are crucial to improve the calibration accuracy. Using the error model, an optimal calibration configuration selection algorithm is developed to determine the least number of measurement configurations as well as the optimal selection of these configurations from the feasible configuration set. To verify the effectiveness of kinematic calibration, a simulation and experiment were performed. The results show that the developed approach can effectively improve accuracy of a parallel kinematic mechanism with relatively low number of calibration configurations.

Design of an Ankle Rehab Robot With a Compliant Parallel Kinematic Mechanism

2020 ◽  
Author(s):  
Nishant Jalgaonkar ◽  
Adam Kim ◽  
Shorya Awtar
Keyword(s):  
Degrees Of Freedom ◽  
Functional Requirements ◽  
Key Factors ◽  
Center Of Rotation ◽  
Ankle Motion ◽  
Natural Motion ◽  
Parallel Kinematic Mechanism ◽  
Parallel Kinematic ◽  
Kinematic Mechanism ◽  
Clinical Adoption

Abstract In this paper, we present the design of a novel ankle rehabilitation robot (ARR), called the Flex-ARR, that employs a compliant parallel kinematic mechanism (PKM) with decoupled degrees of freedom. The Flex-ARR is designed to collocate the biological center of rotation of the ankle with that of the robot’s center of rotation to allow natural ankle motion. While multiple ARR designs have been developed in research labs and some are commercially available, their clinical adoption has been limited because they do not emulate the natural motion of the ankle. The Flex-ARR leverages a unique PKM design that uses compliance to absorb minor misalignments between the center of rotation of the ankle and the robot, thereby allowing natural ankle motion. Also, because of its unique design, the PKM inherently accommodates variations in user foot sizes with minimal adjustments. The Flex-ARR is designed to provide multiple training modes that allow for both rehabilitation and assessment modalities. This paper provides a review of the literature to identify the key factors that have limited the clinical adoption of existing ARRs. Based on this, functional requirements and design specifications for an optimal ARR are defined. This is then used to develop a design strategy, followed by conceptual and detailed design.

Stiffness Analysis of a Tripod With a Passive Link

2005 ◽  
Author(s):  
Z. M. Bi ◽  
S. Y. T. Lang ◽  
D. Zhang
Keyword(s):  
Constrained Motion ◽  
Motion Platform ◽  
Stiffness Analysis ◽  
Stiffness Model ◽  
Parallel Kinematic Mechanism ◽  
Parallel Kinematic ◽  
Linear Actuators ◽  
Main Components ◽  
Kinematic Mechanism

The system stiffness of a tripod parallel kinematic mechanism (PKM) with 3-DOF is investigated in this paper. The tripod PKM has rotations of a motion platform about the x and y axes and translation along the z axis. The motion on the other axes is constrained by a passive link. The stiffness model considers the compliances of three main components: the fixed-length links, the passive link, and the linear actuators. The modeling procedure for the kinetostatic stiffness model is introduced. A case study is provided to demonstrate evaluation of the stiffness of our prototype tripod machine. The developed model differs from the others in the sense that the stiffness on the motion axes is determined by both the active links and the passive link; but the stiffness on the constrained motion axes depends merely on the passive link.

Comparative analysis of a new 3×PPRS parallel kinematic mechanism

2014 ◽  
Vol 30 (4) ◽  
pp. 369-378 ◽  
Author(s):  
Hay Azulay ◽  
Masih Mahmoodi ◽  
Ray Zhao ◽  
James K. Mills ◽  
Beno Benhabib
Keyword(s):  
Comparative Analysis ◽  
Parallel Kinematic Mechanism ◽  
Parallel Kinematic ◽  
Kinematic Mechanism
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