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

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.

2012 ◽  
Vol 516 ◽  
pp. 420-425
Author(s):  
Hong Jian Yu ◽  
Bing Li ◽  
Yang Wang ◽  
Ying Hu

In this paper a novel 4 Degree-of-Freedom (DOF) parallel mechanism with the configuration of 4PUS-1RPU is applied for a 5-axis Hybrid Kinematic Machine (HKM), combined with an additional linear motion. The Parallel Kinematic Mechanism (PKM) is composed of four symmetrical driving chains and one central passive sub-chain. Firstly, the mechanism is described, and the mobility is analyzed. Then the inverse kinematics of the 4-DOF PKM and the direct kinematics for the serial central sub-chain are then presented. The dexterity and the workspace analysis for the mechanism are also carried out. Finally, machining experiment research is presented to verify the effect of the prototype. The research provides the basis for the further parametric design with consideration of kinematic and dexterity performance.


2012 ◽  
Vol 499 ◽  
pp. 3-8
Author(s):  
Xin You Li ◽  
Wu Yi Chen

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.


2020 ◽  
pp. 027836492090990 ◽  
Author(s):  
Matthew A Robertson ◽  
Ozdemir Can Kara ◽  
Jamie Paik

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.


Author(s):  
Chunyang Han ◽  
Yang Yu ◽  
Zhenbang Xu ◽  
Xiaoming Wang ◽  
Peng Yu ◽  
...  

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.


Author(s):  
Nishant Jalgaonkar ◽  
Adam Kim ◽  
Shorya Awtar

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.


Author(s):  
Z. M. Bi ◽  
S. Y. T. Lang ◽  
D. Zhang

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.


2010 ◽  
Vol 4 (4) ◽  
pp. 364-371 ◽  
Author(s):  
Nobuyuki Iwatsuki ◽  
◽  
Norifumi Nishizaka ◽  
Koichi Morikawa ◽  
Koji Kondoh ◽  
...  

This paper describes the kinematic analysis and motion control of a hyper redundant robot built by serially connecting many units with a few DOF. Each unit of the manipulator is a spatial parallel mechanism with 3 DOF and is composed of 2 stages connected with 3 linear actuators, 7 spherical joints, and a center rod. The forward kinematic analysis of the manipulator based on the forward kinematics of each unit by numerical calculation was carried out. The inverse kinematic analysis, the iterative calculation so as to converge output error while output displacement is distributed into each unit with weighting coefficient, was proposed and formulated. Motion control of the robot was theoretically and experimentally examined based on the inverse kinematics. It was confirmed that a prototype with 3 units could generate the desired trajectories.


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