scholarly journals Design Optimization of 3-DOF Redundant Planar Parallel Kinematic Mechanism Based Finishing Cut Stage for Improving Surface Roughness of FDM 3D Printed Sculptures

Mathematics ◽  
2021 ◽  
Vol 9 (9) ◽  
pp. 961
Author(s):  
Minbok Lee ◽  
Hyungjin Jeong ◽  
Donghun Lee
Keyword(s):  
Surface Roughness ◽  
Design Optimization ◽  
Reaction Force ◽  
Torsional Stiffness ◽  
Surface Finishing ◽  
End Effector ◽  
Parallel Kinematic Mechanism ◽  
3D Printed ◽  
Parallel Kinematic ◽  
Kinematic Mechanism

This paper describes the optimal design of a 3-DOF redundant planar parallel kinematic mechanism (PKM) based finishing cut stage to improve the surface roughness of FDM 3D printed sculptures. First, to obtain task-optimized and singularity minimum workspace of the redundant PKM, a weighted grid map based design optimization was applied for a task-optimized workspace without considering the redundancy. For the singularity minimum workspace, the isotropy and manipulability of the end effector of the PKM were carefully modeled under the previously obtained redundancy for optimality. It was confirmed that the workspace size increased by 81.4%, and the internal singularity significantly decreased. To estimate the maximum rated torque and torsional stiffness of all active joints and prevent an undesired end effector displacement of more than 200 , a kinematic stiffness model composed of active and passive kinematic stiffness was derived from the virtual work theorem, and the displacement characteristic at the end effector was examined by applying the reaction force for the PLA surface finishing as an external force acting at the end effector. It was confirmed that the displacement of the end effector of a 1-DOF redundant PKM was not only less than 200 but also decreased from 40.9% to 67.4% compared to a nonredundant actuation.

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.

scholarly journals A Planar Parallel Device for Neurorehabilitation

Robotics ◽  
2020 ◽  
Vol 9 (4) ◽  
pp. 104
Author(s):  
Jawad Yamine ◽  
Alessio Prini ◽  
Matteo Lavit Nicora ◽  
Tito Dinon ◽  
Hermes Giberti ◽  
...  
Keyword(s):  
Single Point ◽  
Point Load ◽  
Experimental Procedure ◽  
Rehabilitation Robots ◽  
Parallel Kinematic Mechanism ◽  
Kinematic Behaviour ◽  
3D Printed ◽  
Parallel Kinematic ◽  
Robotic Devices ◽  
Kinematic Optimization

The patient population needing physical rehabilitation in the upper extremity is constantly increasing. Robotic devices have the potential to address this problem, however most of the rehabilitation robots are technically advanced and mainly designed for clinical use. This paper presents the development of an affordable device for upper-limb neurorehabilitation designed for home use. The device is based on a 2-DOF five-bar parallel kinematic mechanism. The prototype has been designed so that it can be bound on one side of a table with a clamp. A kinematic optimization was performed on the length of the links of the manipulator in order to provide the optimum kinematic behaviour within the desired workspace. The mechanical structure was developed, and a 3D-printed prototype was assembled. The prototype embeds two single-point load cells to measure the force exchanged with the patient. Rehabilitation-specific control algorithms are described and tested. Finally, an experimental procedure is performed in order to validate the accuracy of the position measurements. The assessment confirms an acceptable level of performance with respect to the requirements of the application under analysis.

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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