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ABSTRACT: A five-axis serial-parallel kinematic milling machine, the SPKM 165, is introduced. This machine consists of a three-degree-of-freedom
parallel module and a two-degree-of-freedom serial table. The SPKM 165 is capable of five-face machining. A discussion of
the inverse kinematics of the five-axis control is provided. A dimensional synthesis procedure is presented in terms of motion/force
transmissibility. Finite-element analysis was used to evaluate the stiffness of a CAD model before the machine was manufactured.
Kinematic calibration was implemented to improve the accuracy of the end effector. The results of a calibration experiment
are presented. The stiffness of the developed machine was then measured. Milling experiments were conducted, and the test
piece showed that the developed machine has satisfactory performance.
Keywordsserial-parallel kinematic machine–dimension synthesis–stiffness evaluation–kinematic calibration
Science China Technological Sciences 04/2012; 54(5):1193-1205. · 0.75 Impact Factor
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ABSTRACT: This paper presents a novel step kinematic calibration method for a 3 degree-of-freedom (DOF) planar parallel kinematic machine
tool, based on the minimal linear combinations (MLCs) of error parameters. The method using mapping of linear combinations
of parameters in error transfer multi-parameters coupling system changes the modeling, identification and error compensation
of geometric parameters in the general kinematic calibration into those of linear combinations of parameters. By using the
four theorems of the MLCs, the sets of the MLCs that are respectively related to the relative precision and absolute precision
are determined. All simple and feasible measurement methods in practice are given, and identification analysis of the set
of the MLCs for each measurement is carried out. According to the identification analysis results, a step calibration including
step measurement, step identification and step error compensation is determined by taking into account both measurement costs
and observability. The experiment shows that the proposed method has the following merits: (1) the parameter errors that cannot
influence precision are completely avoided; (2) it reflects the mapping of linear combinations of parameters more accurately
and enhances the precision of identification; and (3) the method is robust, efficient and effective, so that the errors in
position and orientation are kept at the same order of the measurement noise. Due to these merits, the present method is attractive
for the 3-DOF planar parallel kinematic machine tool and can be also applied to other parallel kinematic machine tools with
weakly nonlinear kinematics.
Science in China Series E Technological Sciences 04/2012; 51(12):2165-2177. · 1.02 Impact Factor
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ABSTRACT: Optimal design is one of the most important issues in robots. Since the very beginning, the concepts of the Jacobian matrix,
manipulability and condition number, which are used successfully in the field of serial robots, have been applied to parallel
robots. Unlike serial robots, parallel robots are good for motion/force transmission. Their performance evaluation and design
should be correspondingly different. This paper is an attempt to optimally design a novel spatial three-degree-of-freedom
(3-DOF) parallel robot by using the concept of motion/force transmission. Accordingly, three indices are defined. The suggested
indices are independent of any coordinate frame and could be applied to the analysis and design of a parallel robot whose
singularities can be identified wholly by using the relative angle between the output and adjacent links, and by using the
relative angle between the input and adjacent links.
Science in China Series E Technological Sciences 04/2012; 52(4):986-999. · 1.02 Impact Factor
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ABSTRACT: Performance evaluation is one of the most important issues in the field of parallel kinematic manipulators (PKMs). As a very important class of PKMs, the redundant PKMs have been studied intensively. However, the performance evaluation of this type of PKMs is still unresolved and a challenging endeavor. In this paper, indices that assimilate motion/force transmissibility are proposed to evaluate the performance of redundant PKMs. To illustrate the application of these indices, three PKMs with different kinds of redundancies are taken as examples, and performance atlases are plotted based on the definitions of the indices. Transmissibility comparisons between redundant PKMs and the corresponding non‐redundant ones are carried out. To determine the inverse solutions of the PKMs with kinematic redundancy, an optimization strategy is presented, and the rationality of this method is demonstrated. The indices introduced here can be applied to the performance evaluation of redundant parallel manipulators.
International Journal of Advanced Robotic Systems 11/2011; · 0.38 Impact Factor
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ABSTRACT: Since a parallel robot is always out of control at a singularity and its neighborhood, it should work far away from singular configurations. However, how to measure the closeness between a pose and a singular configuration is still a challenging problem. This paper presents a new measure for closeness to singularities of parallel robots. Several performance indices are introduced by taking into account motion/force transmissibility. By using these indices, a uniform metric can be founded to represent the closeness to singularities for all types of parallel robots.
Robotics and Automation (ICRA), 2011 IEEE International Conference on; 06/2011
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Jinsong Wang,
Xinzhi Peng,
Roberta M Lassance-Soares,
Amir H Najafi,
Lee O Alderman,
Subeena Sood,
Zhenyi Xue,
Rosanna Chan,
James E Faber,
Stephen E Epstein,
Mary Susan Burnett
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ABSTRACT: Despite positive animal studies, clinical angiogenesis trials have been disappointing, possibly due to risk factors present in humans but usually unexplored in animals. We recently demonstrated aging causes impaired collateral remodeling and collateral dropout; here, we investigate potential mechanisms responsible for these findings. Four-, 10-, and 18-month-C57BL/6J mice were subjected to femoral artery ligation; flow was measured using laser Doppler perfusion imaging. Endothelial nitric oxide synthase (eNOS) and phosphorylated eNOS were measured in calf muscle. Apoptosis was assessed in endothelial (EC) and smooth muscle (SMC) cells isolated from young and old mice. Angiogenesis was measured using a Matrigel plug assay. Lethally irradiated young and old mice received bone marrow cells (BMC) from either young or old donors and were subjected to femoral artery ligation (FAL). BMC mobilization and homing were assessed. Flow recovery was impaired and less eNOS and phosphorylated eNOS was present in older vs. young mice (p < 0.001 and p = 0.015, respectively). ECs and SMCs from older mice were more sensitive to an apoptotic stimulus, but were rescued by NO-enhancing drugs. In older mice, angiogenesis (Matrigel plug assay) was impaired, as was mobilization and homing of BM progenitor cells following FAL. Although both mobilization and homing improved when older mice received BMC transplantation from young donors, flow recovery failed to improve. Aging impairs BMC mobilization and homing, collateral responsiveness to angiogenic stimuli, and increases EC and SMC susceptibility to apoptosis via dysfunctional eNOS signaling. The latter could contribute to impaired remodeling and collateral dropout. These finding identify potential obstacles to therapeutic interventions in elderly patients.
Journal of Cardiovascular Translational Research 05/2011; 4(6):779-89. · 2.61 Impact Factor
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Xinzhi Peng, Jinsong Wang,
Roberta M Lassance-Soares,
Amir H Najafi,
Subeena Sood,
Nima Aghili,
Lee O Alderman,
Julio A Panza,
James E Faber,
Shenming Wang,
Stephen E Epstein,
Mary Susan Burnett
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ABSTRACT: Blood flow restoration to ischemic tissue is affected by various risk factors. The aim of this study was to examine gender effects on arteriogenesis and angiogenesis in a mouse ischemic hindlimb model. C57BL/6J mice were subjected to unilateral hindlimb ischemia. Flow recovery was less and hindlimb use impairment was greater in females. No gender difference in vessel number was found at baseline, although 7 days postsurgery females had fewer α-smooth muscle actin-positive vessels in the midpoint of the adductor region. Females had higher hindlimb vascular resistance, were less responsive to vasodilators, and were more sensitive to vasoconstrictors postligation. Western blotting showed that females had higher baseline levels of vascular endothelial growth factor (VEGF) and endothelial nitric oxide synthase (eNOS) in the calf, while 7 days postligation males had higher levels of VEGF, eNOS, and phosphorylated vasodilator stimulated phosphoprotein. Females had less angiogenesis in a Matrigel plug assay and less endothelial cell proliferation in vitro. Females have impaired recovery of flow, a finding presumably caused by multiple factors including decreased collateral remodeling, less angiogenesis, impaired vasodilator response, and increased vasoconstrictor activity; our results also suggest the possibility that new collateral formation, from capillaries, is impaired in females.
AJP Heart and Circulatory Physiology 03/2011; 300(6):H2027-34. · 3.71 Impact Factor
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Robotica. 01/2011; 29:535-546.
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2011 IEEE International Geoscience and Remote Sensing Symposium, IGARSS 2011, Vancouver, BC, Canada, July 24-29, 2011; 01/2011
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2011 IEEE International Geoscience and Remote Sensing Symposium, IGARSS 2011, Vancouver, BC, Canada, July 24-29, 2011; 01/2011
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Intelligent Robotics and Applications - 4th International Conference, ICIRA 2011, Aachen, Germany, December 6-8, 2011, Proceedings, Part I; 01/2011
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Stephan Zbinden, Jinsong Wang,
Remi Adenika,
Marcel Schmidt,
Justin U Tilan,
Amir H Najafi,
Xinzhi Peng,
Roberta M Lassance-Soares,
Micaela Iantorno,
Hakim Morsli,
Leonid Gercenshtein,
Gil Jin Jang,
Stephen E Epstein,
Mary Susan Burnett
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ABSTRACT: In a previous study we identified metallothionein (MT) as a candidate gene potentially influencing collaterogenesis. In this investigation, we determined the effect of MT on collaterogenesis and examined the mechanisms contributing to the effects we found.
Collateral blood flow recovery was assessed using laser Doppler perfusion imaging, and angiogenesis was measured using a Matrigel plug assay. Smooth muscle cells were isolated from MT knockout (KO) mice for functional assays. Gene expression of matrix metalloproteinase-9, platelet-derived growth factor, vascular endothelial growth factor, and Fat cadherin in smooth muscle cells was measured by real-time polymerase chain reaction, and protein levels of vascular endothelial growth factor and matrix metalloproteinase-9 were determined using enzyme-linked immunosorbent assay and Western blot. CD11b(+) macrophages were tested for invasiveness using a real-time impedance assay. Both flow recovery and angiogenesis were impaired in MT KO mice. Proliferation, migration, and invasion were decreased in MT KO smooth muscle cells, and matrix metalloproteinase-9, platelet-derived growth factor, and vascular endothelial growth factor expression were also decreased, whereas FAT-1 cadherin expression was elevated. MT KO CD11b(+) cells were more invasive than wild-type cells.
MT plays an important role in collateral flow recovery and angiogenesis, an activity that appears to be mediated, in part, by the effects of MT on the functionality of 3 cell types essential for these processes: endothelial cells, smooth muscle cells, and macrophages.
Arteriosclerosis Thrombosis and Vascular Biology 03/2010; 30(3):477-82. · 6.37 Impact Factor
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Robotica. 01/2010; 28:937-942.
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IJISCM. 01/2010; 4:258-271.
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IEEE International Geoscience & Remote Sensing Symposium, IGARSS 2010, July 25-30, 2010, Honolulu, Hawaii, USA, Proceedings; 01/2010
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Intelligent Robotics and Applications - Third International Conference, ICIRA 2010, Shanghai, China, November 10-12, 2010. Proceedings, Part I; 01/2010
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ABSTRACT: This paper analyzes the kinematics of a 5-axis serial-parallel kinematic milling machine, i.e., the SPKM 165, which consists
of a three-DOF (degree of freedom) parallel module and a two-DOF serial table. In order to achieve 5-axis control, the inverse
kinematic equations are derived and corresponding coordinate system is established. The relationship between the NC-code and
the operating attitude of the machine is shown and the numerical results are presented.
KeywordsKinematics-Five-axis mechanism-Parallel kinematics-NC-code
12/2009: pages 592-602;
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ABSTRACT: Being as the counterparts of serial robots, parallel manipulators are good at force transmission but not only dexterous manipulation. In this study, a generalized frame-free transmission index is first proposed. Based on the frame-free index, the force transmission performance analysis of spherical 5R parallel manipulators is presented. By giving a specified and significative value, the index can be used to identify a good-transmission workspace (GTW), where the parallel manipulator not only is good at force transmission but also is far away from its singularity. We expect that the proposed index could be applied to the analysis and kinematic optimal design of not only the spherical 5R parallel manipulators but also other fully parallel manipulators.
Reconfigurable Mechanisms and Robots, 2009. ReMAR 2009. ASME/IFToMM International Conference on; 07/2009
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ABSTRACT: This paper deals with the experimental study of a redundantly actuated parallel manipulator for a 5-DOF hybrid machine tool. Based on the kinematics of the redundantly actuated parallel manipulator, the inverse dynamics is derived by using the virtual work principle. A position and force switching control strategy is used for the two extendible chains of the parallel manipulator. Further, the difference predictive control is presented for the extendible chain with force mode. The parallel manipulator is incorporated into a 5-DOF hybrid machine tool. Linear and circular contouring experiments of both the hybrid machine tool as well as its corresponding nonredundant counterpart with the redundant limb removed are conducted to evaluate the machine performance. Finally, the machine experiment is used to demonstrate the machine's applicability.
IEEE/ASME Transactions on Mechatronics 03/2009; · 2.87 Impact Factor
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Robotica. 01/2009; 27:51-57.
