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1
Fowler, R. M., L. L. Howell, and S. P. Magleby. "Compliant space mechanisms: a new frontier for compliant mechanisms." Mechanical Sciences 2, no. 2 (2011): 205–15. http://dx.doi.org/10.5194/ms-2-205-2011.
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Abstract. Compliant mechanisms offer distinct advantages for use in space that can address many of the issues encountered with current rigid-link space mechanisms. Compliant space mechanisms are defined as moveable mechanical assemblies that achieve their desired motion, force, or displacement by means of the deflection of flexible members and can perform a necessary function in the environments of launch and space. Many current space mechanisms are already highly optimized, yet they still experience inherent challenges, and it is unclear if significant improvements in performance can be made by continuing to refine current designs. Compliant space mechanisms offer a promising opportunity to change the fundamental approach to achieving controlled motion in space systems and have potential for dramatic increases in mechanism performance given the constraints of the space environment. This paper proposes the merger of the fields of compliant mechanisms and space mechanisms as a future direction of research in compliant mechanisms, discusses in detail the motivation to do so, and addresses the key factors of applying compliant mechanism technology to space mechanisms.
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Kiener, Lionel, Hervé Saudan, Florent Cosandier, Gérald Perruchoud, and Peter Spanoudakis. "Innovative concept of compliant mechanisms made by additive manufacturing." MATEC Web of Conferences 304 (2019): 07002. http://dx.doi.org/10.1051/matecconf/201930407002.
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The complete redesign for Additive Manufacturing of compliant mechanism structures enables CSEM to develop innovative concepts to drastically reduce the need of machining and assembly after additive manufacturing. Support structures under flexure blades are thus minimised and the overall process becomes more streamlined. Moreover, this concept allows us to easily design and produce monolithic cross flexure pivots with interlocked flexible blades. Based on this concept, CSEM is now developing new architectures of Compliant Mechanisms based on Additive Manufacturing (COMAM) for the European Space Agency (ESA) in the frame of a GSTP research project. The past and current work of design, 3D printing and testing on several compliant mechanisms are presented. These demonstrators will be used as use-case for future high-precision and harsh environment applications such as cryogenic and space.
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Xu, Dong, and G. K. Ananthasuresh. "Freeform Skeletal Shape Optimization of Compliant Mechanisms." Journal of Mechanical Design 125, no. 2 (2003): 253–61. http://dx.doi.org/10.1115/1.1563634.
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Compliant mechanisms are elastic continua used to transmit or transform force and motion mechanically. The topology optimization methods developed for compliant mechanisms also give the shape for a chosen parameterization of the design domain with a fixed mesh. However, in these methods, the shapes of the flexible segments in the resulting optimal solutions are restricted either by the type or the resolution of the design parameterization. This limitation is overcome in this paper by focusing on optimizing the skeletal shape of the compliant segments in a given topology. It is accomplished by identifying such segments in the topology and representing them using Bezier curves. The vertices of the Bezier control polygon are used to parameterize the shape-design space. Uniform parameter steps of the Bezier curves naturally enable adaptive finite element discretization of the segments as their shapes change. Practical constraints such as avoiding intersections with other segments, self-intersections, and restrictions on the available space and material, are incorporated into the formulation. A multi-criteria function from our prior work is used as the objective. Analytical sensitivity analysis for the objective and constraints is presented and is used in the numerical optimization. Examples are included to illustrate the shape optimization method.
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Krishnan, G., C. Kim, and S. Kota. "Building block method: a bottom-up modular synthesis methodology for distributed compliant mechanisms." Mechanical Sciences 3, no. 1 (2012): 15–23. http://dx.doi.org/10.5194/ms-3-15-2012.
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Abstract. Synthesizing topologies of compliant mechanisms are based on rigid-link kinematic designs or completely automated optimization techniques. These designs yield mechanisms that match the kinematic specifications as a whole, but seldom yield user insight on how each constituent member contributes towards the overall mechanism performance. This paper reviews recent developments in building block based design of compliant mechanisms. A key aspect of such a methodology is formulating a representation of compliance at a (i) single unique point of interest in terms of geometric quantities such as ellipses and vectors, and (ii) relative compliance between distinct input(s) and output(s) in terms of load flow. This geometric representation provides a direct mapping between the mechanism geometry and their behavior, and is used to characterize simple deformable members that form a library of building blocks. The design space spanned by the building block library guides the decomposition of a given problem specification into tractable sub-problems that can be each solved from an entry in the library. The effectiveness of this geometric representation aids user insight in design, and enables discovery of trends and guidelines to obtain practical conceptual designs.
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Hao, Guangbo, Haiyang Li, and Richard Kavanagh. "Design of decoupled, compact, and monolithic spatial translational compliant parallel manipulators based on the position space." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 230, no. 3 (2015): 367–78. http://dx.doi.org/10.1177/0954406215596883.
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The initial version of this paper was presented at 2014 Workshop on Fundamental Issues and Future Research Directions for Parallel Mechanisms and Manipulators, Tianjin, China. The conceptual design of three types of decoupled, compact, and monolithic XYZ compliant parallel manipulators (CPMs) is taken into account in this paper using the position space concept. The CPMs are termed CUBEs due to the shape of their compact structures. The position space of a compliant module is the combination of all permitted positions in an XYZ CPM system where the constraint of this compliant module in the XYZ CPM system remains unchanged when the position of the compliant module changes within the position space. The position of each compliant P joint is considered relative to its adjacent compliant joint/module rather than being considered in insolation. A design method for obtaining monolithic XYZ CPMs is proposed in terms of both the kinematic substitution and position spaces. Three types of monolithic XYZ CPMs are then demonstrated using the proposed method, with the help of three classes of kinematically decoupled three degrees of freedom translational parallel mechanisms. These monolithic XYZ CPMs include a 3- PPP (P: prismatic) XYZ CPM, a 3- PPPR (R: revolute) XYZ CPM, and a 3- PPPRR XYZ CPM. The position space concept can enable the system configurations to be designed based on the chosen optimization requirements, which include considerations such as compactness or minimization of parasitic rotations. This provides an efficient and systematic method to arrange the relative position between any two compliant joints/modules so that one can easily generate practical and useful configurations for XYZ CPMs. The resulting XYZ CPM is the most compact one when the fixed ends of the three actuated compliant P joints thereof overlap or are as close to each other as possible.
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Kim, Charles J., Sridhar Kota, and Yong-Mo Moon. "An Instant Center Approach Toward the Conceptual Design of Compliant Mechanisms." Journal of Mechanical Design 128, no. 3 (2005): 542–50. http://dx.doi.org/10.1115/1.2181992.
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As with conventional mechanisms, the conceptual design of compliant mechanisms is a blend of art and science. It is generally performed using one of two methods: topology optimization or the pseudo-rigid-body model. In this paper, we present a new conceptual design methodology which utilizes a building block approach for compliant mechanisms performing displacement amplification/attenuation. This approach provides an interactive, intuitive, and systematic methodology for generating initial compliant mechanism designs. The instant center is used as a tool to construct the building blocks. The compliant four-bar building block and the compliant dyad building block are presented as base mechanisms for the conceptual design. It is found that it is always possible to obtain a solution for the geometric advantage problem with an appropriate combination of these building blocks. In a building block synthesis, a problem is first evaluated to determine if any known building blocks can satisfy the design specifications. If there are none, the problem is decomposed to a number of sub-problems which may be solved with the building blocks. In this paper, the problem is decomposed by selecting a point in the design space where the output of the first building block coincides with the second building block. Two quantities are presented as tools to aid in the determination of the mechanism's geometry – (i) an index relating the geometric advantage of individual building blocks to the target geometric advantage and (ii) the error in the geometric advantage predicted by instant centers compared to the calculated value from FEA. These quantities guide the user in the selection of the location of nodes of the mechanism. Determination of specific cross-sectional size is reserved for subsequent optimization. An example problem is provided to demonstrate the methodology's capacity to obtain good initial designs in a straightforward manner. A size and geometry optimization is performed to demonstrate the viability of the design.
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Hull, Patrick V., and Stephen Canfield. "Optimal Synthesis of Compliant Mechanisms Using Subdivision and Commercial FEA." Journal of Mechanical Design 128, no. 2 (2005): 337–48. http://dx.doi.org/10.1115/1.2159026.
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The field of distributed-compliance mechanisms has seen significant work in developing suitable topology optimization tools for their design. These optimal design tools have grown out of the techniques of structural optimization. This paper will build on the previous work in topology optimization and compliant mechanism design by proposing an alternative design space parametrization through control points and adding another step to the process, that of subdivision. The control points allow a specific design to be represented as a solid model during the optimization process. The process of subdivision creates an additional number of control points that help smooth the surface (for example a C2 continuous surface depending on the method of subdivision chosen) creating a manufacturable design free of some traditional numerical instabilities. Note that these additional control points do not add to the number of design parameters. This alternative parametrization and description as a solid model effectively and completely separates the design variables from the analysis variables during the optimization procedure. The motivation behind this work is to create an automated design tool from task definition to functional prototype created on a CNC or rapid-prototype machine. This paper will describe the proposed compliant mechanism design process and will demonstrate the procedure on several examples common in the literature.
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Tran, Ngoc Thoai, Ngoc Le Chau, and Thanh-Phong Dao. "A Hybrid Computational Method of Desirability, Fuzzy Logic, ANFIS, and LAPO Algorithm for Multiobjective Optimization Design of Scott Russell Compliant Mechanism." Mathematical Problems in Engineering 2020 (April 27, 2020): 1–28. http://dx.doi.org/10.1155/2020/3418904.
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Flexure-based compliant mechanisms are increasingly promising in precision engineering, robotics, and other applications, thanks to the excellent advantages of no friction, no backlash, no wear, and minimal assembly. However, their design and analysis are still challenging due to the coupling of kinematic-mechanical behaviors with large nonlinear deflections in comparison to their rigid-body counterparts. Optimal design is an important aspect in the field of compliant mechanisms and has attracted much attention during the last decades. Especially, when considering a multiobjective optimization design for compliant mechanisms, the problem is becoming more complicated. Thus, this article presents a new efficient hybrid computational method to resolve multiobjective optimization design of compliant mechanisms. A Scott Russell compliant mechanism is employed as the design example and to show the advantages of the proposed optimizing method. The proposed method is developed by hybridizing the desirability function approach, fuzzy logic system, adaptive neuro-fuzzy inference system (ANFIS), and lightning attachment procedure optimization (LAPO). First of all, a 3D finite element model is created and central composite design is employed to build a numerical matrix. First, design variables are refined by using analysis of variance and Taguchi approach in terms of considerably eliminating space of design variables. Subsequently, desirability values of two objective functions are determined and transferred into the fuzzy logic system. The output of the fuzzy logic system is considered as a single combined objective function. Next, modeling for fuzzy output is established via developing the ANFIS model. At last, the LAPO algorithm is adopted for solving the multiobjective optimization problem for the mechanism. Three numerical examples are investigated to validate the feasibility and the effectiveness of performance efficiency of the proposed methodology. The results find that the proposed methodology is more efficient than traditional Taguchi-based fuzzy logic. Besides, the performance efficiency of the proposed approach outperforms the Jaya algorithm and TLBO algorithm through the Wilcoxon signed rank test and Friedman test. The results of this article give a useful approach for complex optimization problems.
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Wiedmann, Stephen, and Bob Sturges. "Spatial Kinematic Analysis of Threaded Fastener Assembly." Journal of Mechanical Design 128, no. 1 (2005): 116–27. http://dx.doi.org/10.1115/1.2114909.
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Compliant mechanisms for rigid part mating exist for prismatic geometries. A few instances are known of mechanisms to assemble screw threads. A comprehensive solution to this essentially geometric problem comprises at least three parts: parametric equations for nut and bolt contact in the critical starting phase of assembly, the possible space of motions between these parts during this phase, and the design space of compliant devices which accomplish the desired motions in the presence of friction and positional uncertainty. This work concentrates on the second part in which the threaded pair is modeled numerically, and contact tests are automated through software. Tessellated solid models were used during three-dimensional collision analysis to enumerate the approximate location of the initial contact point. The advent of a second contact point presented a more constrained contact state. Thus, the bolt is rotated about a vector defined by the initial two contact points until a third contact location was found. By analyzing the depth of intersection of the bolt into the nut as well as the vertical movement of the origin of the bolt reference frame, we determined that there are three types of contacts states present: unstable two-point, quasi-stable two-point, stable three point. The space of possible motions is bounded by these end conditions which will differ in detail depending upon the starting orientations. We investigated all potential orientations which obtain from a discretization of the roll, pitch, and yaw uncertainties, each of which has its own set of contact points. From this exhaustive examination, a full contact state history was determined, which lays the foundation for the design space of either compliant mechanisms or intelligent sensor-rich controls.
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Vincent, J. F. V. "Deployable Structures in Nature: Potential for Biomimicking." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 214, no. 1 (2000): 1–10. http://dx.doi.org/10.1177/095440620021400101.
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Biology contains many examples of deployable structures. They can be grouped as planar, cylindrical, stiff and compliant, and space frame combining both stiff and compliant elements (ten-segrity structures). Deployment occurs due to high strain elastic materials, or folds and curves that can be actuated by springs, changes in shape (mediated by hydraulic or contractile mechanisms) or changes in stiffness. Evolution filters out inefficiency. Transfer of nature's technology requires understanding of the optimizations in the biological system. The concepts can then be used in aerospace, deployable camouflage, packaging, emergency shelters, capture systems, etc.
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Liu, Lang, Shusheng Bi, and Qizi Yang. "Stiffness characteristics of inner–outer ring flexure pivots applied to the ultra-precision instruments." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 232, no. 13 (2017): 2441–57. http://dx.doi.org/10.1177/0954406217721725.
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The inner-outer ring flexure pivot (IORFP), composed of three straight springs that cross each other in space, is studied in this work. First, to emphasize the study value of IORFP, qualitative comparison is applied to IORFP and some of most commonly used flexure pivots. Then an analytical model for the rotational stiffness of IORFP is developed based on the strain energy formulation of a beam flexure, and model applicability is provided as well. Analysis of stiffness, buckling load, and the nonlinear of moment–rotation relation is then carried out. Subsequently, the analytical model is verified by finite element analysis. After that, seven prototypes of IORFP are manufactured, and their rotational stiffnesses are tested. The results show that the analytical model can be used for analysis and designing of compliant mechanisms that contain IORFP. Finally, the study quantitatively compares stiffness characteristics and axis drift of IORFP and the generalized cross-spring pivot, indicating that the former significantly outperforms the latter. IORFP possesses excellent performances and can be widely used to supplant generalized cross-spring pivot in compliant mechanisms and ultra-precision instruments.
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Fukui, Rui, Taketoshi Mori, and Tomomasa Sato. "Home-Use Object Transfer/Storage Robot System with Compliant Strategy and Mechanism (Commodities Management and its Extended Application of Daily Life Support for the Elderly)." Journal of Robotics and Mechatronics 23, no. 4 (2011): 532–43. http://dx.doi.org/10.20965/jrm.2011.p0532.
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This research describes the strategy and mechanism design methodology to realize a robot system that transfers and stores daily use objects in our living space. Unlike industrial applications, there are three specific problems in the home application: (1) variation of living environment, (2) diversity of daily use objects, (3) dispersion of human activity. First, we presented a concept of strategic compliance as a basic solution for these problems and extracted three fundamental functions (regulation, assist/enforce, and navigation) for the strategy. Second, we aimed to realize a robust robot motion by introducing adequate mechanisms which are suitable for the strategy. The mechanisms are; (1) passive mechanical compliance and (2) object constraint methodology with “caging.” As an actual prototype system, a home-use logistical support robot system implemented with those strategies and mechanisms is constructed. By experiments, validity of the presented methodology was confirmed. In addition to the domestic logistical application, we considered applying the proposed system to the elderly people support, and developed prototypes of supporting instruments; lavatory and refrigerator containers. The basic design of the instruments is also introduced.
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Damm, Loïc, and Joseph McIntyre. "Physiological Basis of Limb-Impedance Modulation During Free and Constrained Movements." Journal of Neurophysiology 100, no. 5 (2008): 2577–88. http://dx.doi.org/10.1152/jn.90471.2008.
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Arm stiffness is a critical factor underlying stable interactions with the environment. When the hand moves freely through space, a stiff limb would most effectively maintain the hand on the desired path in the face of external perturbations. Conversely, when constrained by a rigid surface, a compliant limb would allow the surface to guide the hand while minimizing variations in contact forces. We aimed to identify the physiological basis of stiffness adaptation for these two classes of movement. Stiffness can be regulated by two mechanisms: coactivation of antagonistic muscles and modulation of reflex gains. We hypothesized that subjects would select high stiffness (high coactivation and/or reflex gains) in free space and high compliance (low coactivation and reflex gains) for constrained movements. We measured EMG and the H-reflex during constrained and unconstrained movement of the wrist. As predicted, subjects coactivated antagonist muscles more when performing the unconstrained movement. Contrary to our hypothesis, however, H-reflex amplitude was higher for the constrained movement despite the a priori preference for lower reflex gains in this situation. In addition, the H-reflex depended on the task and the net force exerted by the limb on the environment, rather than showing a simple dependence on the level of muscle activation. Thus stiffness seems to increase in free space compared with constrained motion through the use of coactivation, whereas spinal loop gains are adjusted to better regulate the influence of afferences on the ongoing movement. These observations support the hypothesis of movement programming in terms of impedance.
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Guazzi, Marco, Gloria Tamborini, and Anna Maltagliati. "Changes in Pulmonary Venous Return during Head-up Tilting in Man." Clinical Science 93, no. 1 (1997): 13–20. http://dx.doi.org/10.1042/cs0930013.
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1. In a supine position, the heart fills to close to the limits of pericardial constraint and the pericardium may act to redistribute central blood volume from the left side of the heart back to the more compliant lung. 2. We probed whether, and through which mechanisms, a redistribution of blood from the lungs to the left heart occurs during vertical displacement and compensates for reduced venous return. 3. We investigated 16 normal volunteers with Doppler-echocardiography during 20°, 40° and 60° head-up tilting. Tilting was stopped at 10 min in 10 subjects (group 1) and at 45 min in 6 subjects (group 2). 4. At 10 min we observed a reduction in right ventricular diastolic dimension and left ventricular end-diastolic pressure, as estimated by the difference between the duration of the pulmonary venous flow during atrial contraction (Z wave) and that of the mitral A wave. We also recorded a decrease during systole (X wave) and an increase during diastole (Y wave) of the pulmonary venous forward flow velocity. These variations were evident at 20° and became progressively greater with increasing degrees of tilting. In group 2, changes at 10 min and at 45 min for any degree of displacement were similar. 5. A decrease in right ventricular dimensions (ventricular interdependence) and underfilling of the lung compartment due to volume redistribution to the periphery (diminished lung contribution to pericardial constraint) augment compliance within the pericardial space, reduce downstream pressure for pulmonary venous return and move the pulmonary venous flow predominantly to ventricular diastole, allowing diastolic filling. 6. During head-up tilting a favourable interaction between heart and lungs increases compliance within the pericardial space and facilitates redistribution of blood from the lungs, resulting in a sustained compensation for the reduced venous return.
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Kim, Chunghwan, Won June Choi, Yisha Ng, and Wonmo Kang. "Mechanically Induced Cavitation in Biological Systems." Life 11, no. 6 (2021): 546. http://dx.doi.org/10.3390/life11060546.
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Cavitation bubbles form in soft biological systems when subjected to a negative pressure above a critical threshold, and dynamically change their size and shape in a violent manner. The critical threshold and dynamic response of these bubbles are known to be sensitive to the mechanical characteristics of highly compliant biological systems. Several recent studies have demonstrated different biological implications of cavitation events in biological systems, from therapeutic drug delivery and microsurgery to blunt injury mechanisms. Due to the rapidly increasing relevance of cavitation in biological and biomedical communities, it is necessary to review the current state-of-the-art theoretical framework, experimental techniques, and research trends with an emphasis on cavitation behavior in biologically relevant systems (e.g., tissue simulant and organs). In this review, we first introduce several theoretical models that predict bubble response in different types of biological systems and discuss the use of each model with physical interpretations. Then, we review the experimental techniques that allow the characterization of cavitation in biologically relevant systems with in-depth discussions of their unique advantages and disadvantages. Finally, we highlight key biological studies and findings, through the direct use of live cells or organs, for each experimental approach.
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Merriam, E. G., J. E. Jones, S. P. Magleby, and L. L. Howell. "Monolithic 2 DOF fully compliant space pointing mechanism." Mechanical Sciences 4, no. 2 (2013): 381–90. http://dx.doi.org/10.5194/ms-4-381-2013.
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Abstract. This paper describes the conception, modeling, and development of a fully compliant two-degree-of-freedom pointing mechanism for application in spacecraft thruster, antenna, or solar array systems. The design objectives and the advantages of a compliant solution are briefly discussed. Detailed design decisions to meet project objectives are described. Analytical and numerical models are developed and subsequently verified by prototype testing and measurements in several iterations. A final design of the 3-D printed titanium monolithic pointing mechanism is described in detail and its performance is measured.
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Ai, Haiping, An Zhu, Jiajia Wang, Xiaoyan Yu, and Li Chen. "Buffer Compliance Control of Space Robots Capturing a Non-Cooperative Spacecraft Based on Reinforcement Learning." Applied Sciences 11, no. 13 (2021): 5783. http://dx.doi.org/10.3390/app11135783.
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Aiming at addressing the problem that the joints are easily destroyed by the impact torque during the process of space robot on-orbit capturing a non-cooperative spacecraft, a reinforcement learning control algorithm combined with a compliant mechanism is proposed to achieve buffer compliance control. The compliant mechanism can not only absorb the impact energy through the deformation of its internal spring, but also limit the impact torque to a safe range by combining with the compliance control strategy. First of all, the dynamic models of the space robot and the target spacecraft before capture are obtained by using the Lagrange approach and Newton-Euler method. After that, based on the law of conservation of momentum, the constraints of kinematics and velocity, the integrated dynamic model of the post-capture hybrid system is derived. Considering the unstable hybrid system, a buffer compliance control based on reinforcement learning is proposed for the stable control. The associative search network is employed to approximate unknown nonlinear functions, an adaptive critic network is utilized to construct reinforcement signal to tune the associative search network. The numerical simulation shows that the proposed control scheme can reduce the impact torque acting on joints by 76.6% at the maximum and 58.7% at the minimum in the capturing operation phase. And in the stable control phase, the impact torque acting on the joints were limited within the safety threshold, which can avoid overload and damage of the joint actuators.
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Guzmán-Díaz, J., I. Mendigutía, B. Montesinos, et al. "Homogeneous study of Herbig Ae/Be stars from spectral energy distributions and Gaia EDR3." Astronomy & Astrophysics 650 (June 2021): A182. http://dx.doi.org/10.1051/0004-6361/202039519.
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Context. Herbig Ae/Be stars (HAeBes) have so far been studied based on relatively small samples that are scattered throughout the sky. Their fundamental stellar and circumstellar parameters and statistical properties were derived with heterogeneous approaches before Gaia. Aims. Our main goal is to contribute to the study of HAeBes from the largest sample of such sources to date, for which stellar and circumstellar properties have been determined homogeneously from the analysis of the spectral energy distributions (SEDs) and Gaia EDR3 parallaxes and photometry. Methods. Multiwavelength photometry was compiled for 209 bona fide HAeBes for which Gaia EDR3 distances were estimated. Using the Virtual Observatory SED Analyser (VOSA), photospheric models were fit to the optical SEDs to derive stellar parameters, and the excesses at infrared (IR) and longer wavelengths were characterized to derive several circumstellar properties. A statistical analysis was carried out to show the potential use of such a large dataset. Results. The stellar temperature, luminosity, radius, mass, and age were derived for each star based on optical photometry. In addition, their IR SEDs were classified according to two different schemes, and their mass accretion rates, disk masses, and the sizes of the inner dust holes were also estimated uniformly. The initial mass function fits the stellar mass distribution of the sample within 2 < M*∕M⊙ < 12. In this aspect, the sample is therefore representative of the HAeBe regime and can be used for statistical purposes when it is taken into account that the boundaries are not well probed. Our statistical study does not reveal any connection between the SED shape from the Meeus et al. (2001, A&A, 365, 476) classification and the presence of transitional disks, which are identified here based on the SEDs that show an IR excess starting at the K band or longer wavelengths. In contrast, only ~28% of the HAeBes have transitional disks, and the related dust disk holes are more frequent in HBes than in HAes (~34% vs. 15%). The relatively small inner disk holes and old stellar ages estimated for most transitional HAes indicate that photoevaporation cannot be the main mechanism driving disk dissipation in these sources. In contrast, the inner disk holes and ages of most transitional HBes are consistent with the photoevaporation scenario, although these results alone do not unambiguously discard other disk dissipation mechanisms. Conclusions. The complete dataset is available online through a Virtual Observatory-compliant archive, representing the most recent reference for statistical studies on the HAeBe regime. VOSA is a complementary tool for the future characterization of newly identified HAeBes.
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Mascareñas, David, Fernando Moreu, Precious Cantu, et al. "A compliant mechanism for inspecting extremely confined spaces." Smart Materials and Structures 26, no. 11 (2017): 115028. http://dx.doi.org/10.1088/1361-665x/aa9195.
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Mathew, Bilji c., Vishal bharatpatil, Anilchamoli, Muskan Raikwar, Mahesh Singh Negi, and Harparlad Singh. "Compliant Mechanism and Origami usage in Aerospace and Space Application." IOP Conference Series: Earth and Environmental Science 775, no. 1 (2021): 012008. http://dx.doi.org/10.1088/1755-1315/775/1/012008.
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Kim, Whee-kuk, Byung-Ju Yi, and Whang Cho. "RCC Characteristics of Planar/Spherical Three Degree-of-Freedom Parallel Mechanisms With Joint Compliances." Journal of Mechanical Design 122, no. 1 (2000): 10–16. http://dx.doi.org/10.1115/1.533541.
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A three degree-of-freedom (DOF) planar parallel manipulator has been extensively studied as the fundamental example of parallel manipulators. In this work, we explicitly show that this mechanism possesses a completely decoupled compliance characteristic at the object space, which is the important operational requirement for a RCC device. As the first condition to have a RCC point, this mechanism should maintain symmetric configurations. As the second condition, the same magnitude of revolute joint compliance should be symmetrically placed at the same joint location of each chain. We also investigate the compliance characteristics of a spherical 3 DOF mechanism which has a similar kinematic structure to the planar mechanism through simulation. It turns out that the spherical mechanism also has a RCC point at the intersection point of all nine joint axes in its symmetric configuration. Further, more general output compliance model is derived for those mechanisms with redundant joint compliances. It is expected that these two parallel mechanisms not only can be used as excellent 3 DOF RCC devices, but also can be integrated into the design of a new six DOF RCC device. [S1050-0472(00)01101-6]
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Сальков, Николай, and Nikolay Sal'kov. "Formation of Cyclic Surfaces in Kinetic Geometry." Geometry & Graphics 5, no. 4 (2017): 24–36. http://dx.doi.org/10.12737/article_5a17fbe3680f52.30844454.
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This paper is an evolution of the "Kinematic Compliance of Rotating Spaces" paper, previously published in the "Geometry and Graphics" journal №1, 2013. A great many of mechanisms are making rotational movement, wherein rotating parts of one mechanism are "invading" into a rotation zone belonging to parts of another rotating mechanism. The challenge is to prevent the collision of rotating parts belonging to two or more details with each other. This problem is particularly sensitive for machine engineering. In space navigation, where, in principle, there are no objects that are at rest, the problem of satellites collision with astronomical bodies rotating around their axes is also the urgent one. Therefore, the theory of kinematic matching for rotating spaces R31 and R32 when they are moving independently from each other is urgent too. Each of two considered spaces may have a uniform or non-uniform movement in a given direction, a curved movement or a rotational movement around the axis specified for each space. In this paper has been considered the formation of cyclic surfaces obtained by rotation of one space relative to another one and different orientations of the generating line relative to the axes. Has been considered one of the options for rotating spaces, when their axes are parallel. In such a case the generating line is located in the following positions: it is straight and parallel to the axis; it is straight and intersects the axis; the rectilinear generator is in a plane that is parallel to the plane of the axes; the generating line is a straight line of general position; the generating line is a space curve. Has been demonstrated application of the rotating spaces theory in mining, chemical and machine tool industries, made in the form of inventions, confirmed by copyright certificates of the USSR.
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Sekaran, S., A. Tkachenko, C. Johnston, and C. Aerts. "A comparison of the dynamical and model-derived parameters of the pulsating eclipsing binary KIC 9850387." Astronomy & Astrophysics 648 (April 2021): A91. http://dx.doi.org/10.1051/0004-6361/202040154.
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Context. One-dimensional stellar evolutionary models incorporate interior mixing profiles as a simplification of multi-dimensional physical processes that have a significant impact on the evolution and lifetime of stars. As such, the proper calibration of interior mixing profiles is required for the reconciliation of observational parameters and theoretical predictions. The modelling and analysis of pulsating stars in eclipsing binary systems that display gravity-mode (g-mode) oscillations allows for the precise constraints on the interior mixing profiles through the combination of spectroscopic, binary and asteroseismic obervables. Aims. We aim to unravel the interior mixing profile of the pulsating eclipsing binary KIC 9850387 by comparing its dynamical parameters and the parameters derived through a combination of evolutionary and asteroseismic modelling. Methods. We created a grid of stellar evolutionary models using the stellar evolutionary code MESA and performed an isochrone-cloud (isocloud) based evolutionary modelling of the system. We then generated a grid of pulsational models using the stellar pulsation code GYRE based on the age constraints from the evolutionary modelling. Finally, we performed asteroseismic modelling of the observed ℓ = 1 and ℓ = 2 period-spacing patterns, utilising different combinations of observational constraints, merit functions, and asteroseismic observables to obtain strong constraints on the interior properties of the primary star. Results. Through a combination of asteroseismic modelling and dynamical constraints, we found that the system comprises two main-sequence components at an age of 1.2 ± 0.1 Gyr. We also observed that asteroseismic modelling provided stronger constraints on the interior properties than evolutionary modelling. Overall, we found high levels of interior mixing, when compared to similar studies, for the primary star. We posited that this is a result of intrinsic non-tidal mixing mechanisms due to a similar observed behaviour in single stars. We investigated the high-frequency regime of KIC 9850387 and found evidence of the surface effect due to the systematic frequency offset of the theoretical modes from the nearest observed modes. We also found evidence of rotational splitting in the form of a prograde-retrograde dipole g1 mode doublet with a missing zonal mode, implying an envelope rotational frequency that is three times higher than the core rotational frequency and about 20 times slower than the orbital frequency, but we note that this result is based completely on the rotational splitting of a single dipole mode. Conclusions. We find that the dynamical parameters and the parameters extracted from the asteroseismic modelling of period-spacing patterns are only barely compliant, reinforcing the need for homogeneous analyses of samples of pulsating eclipsing binaries that aim to calibrating interior mixing profiles.
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Lin, Sheng, Jian Xu, and Chun Wang. "A Novel Compliant Mechanism with Three Degrees of Freedom." Applied Mechanics and Materials 373-375 (August 2013): 72–75. http://dx.doi.org/10.4028/www.scientific.net/amm.373-375.72.
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A novel compliant mechanism with three degree of freedom (DOF) is proposed, based on the method of Freedom and Constraint Topology (FACT). One movement and two rotations are obtained in Case 3, Type 2 freedom space. A redundant constraint is added to improve the symmetry. The finite element modal (FEM) is established and static force analysis is conducted. Results demonstrate that the compliant mechanism is decoupled. Modal analysis is carried out with the finite element method. And four orders natural frequency and main vibration mode are obtained.
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Li, Yan, Wenjie Ge, Xu Zhang, and Xinxing Tong. "Optimization and Experiment of a Novel Compliant Focusing Mechanism for Space Remote Sensor." Sensors 20, no. 23 (2020): 6826. http://dx.doi.org/10.3390/s20236826.
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The change of an external environment leads to the defocusing phenomenon of the space optical remote sensor. The performance of the focusing mechanism is related to the image quality of the remote sensor. It was optimized for a novel focusing mechanism comprised of a flexural hinge lever-type amplifier and several piezoelectric ceramics to improve the performance on high loads and large stroke in this research. It has advantages of a lightweight, simple structure and high reliability compared with the traditional focusing mechanism. The input displacement from the piezoelectric actuators was amplified by a two-stage flexure hinge lever-type mechanism. Dimensional parameters of the flexural hinges were considered as design variables. Based on the optimization ideology, reasonable compliance and dimension parameters of the flexural hinges were analyzed for the focusing mechanism. Simulation and experiments of deformation were conducted to validate the correctness of design optimization. The results show that the focusing mechanism designed by the proposed method has the capabilities of an amplification ratio of 100 times and a loading carrying capacity of 2 kg. This work provides a novel strategy to design an excellent focusing mechanism with lightweight, high loads and large stroke. Moreover, it is believed that this approach can be extended to other complex sensors.
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Liu, Nailong, Xiaodong Zhou, Zhaoming Liu, Hongwei Wang, and Long Cui. "Learning peg-in-hole assembly using Cartesian DMPs with feedback mechanism." Assembly Automation 40, no. 6 (2020): 895–904. http://dx.doi.org/10.1108/aa-04-2020-0053.
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Purpose This paper aims to enable the robot to obtain human-like compliant manipulation skills for the peg-in-hole (PiH) assembly task by learning from demonstration. Design/methodology/approach A modified dynamic movement primitives (DMPs) model with a novel hybrid force/position feedback in Cartesian space for the robotic PiH problem is proposed by learning from demonstration. To ensure a compliant interaction during the PiH insertion process, a Cartesian impedance control approach is used to track the trajectory generated by the modified DMPs. Findings The modified DMPs allow the robot to imitate the trajectory of demonstration efficiently and to generate a smoother trajectory. By taking advantage of force feedback, the robot shows compliant behavior and could adjust its pose actively to avoid a jam. This feedback mechanism significantly improves the dynamic performance of the interactive process. Both the simulation and the PiH experimental results show the feasibility and effectiveness of the proposed model. Originality/value The trajectory and the compliant manipulation skill of the human operator can be learned simultaneously by the new model. This method adopted a modified DMPs model in Cartesian space to generate a trajectory with a lower speed at the beginning of the motion, which can reduce the magnitude of the contact force.
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Lin, Sheng, and Shiqi Song. "Hybrid curved beam compliant mechanism with six degrees of freedom and large working space." IOP Conference Series: Materials Science and Engineering 569 (August 9, 2019): 022028. http://dx.doi.org/10.1088/1757-899x/569/2/022028.
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Davydov, Vladimir Nikolaevich. "Fishery in ‘free spaces’: non-compliance with fishery regulations in a northern Baikal Evenki village." Polar Record 50, no. 4 (2014): 379–90. http://dx.doi.org/10.1017/s0032247414000163.
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ABSTRACTDuring the post-Soviet period, fishery became one of the main sources of income for the inhabitants of Evenki villages in the northern Baikal region. When a number of villagers lost their official jobs, they managed to earn money by selling fish. Most people are required to fish during a particular season and to follow official quotas. Special indigenous Evenki quotas, however, are usually in excess of regular official guidelines and those who can use these quotas usually exceed them. This results in a tension between the way local Evenki people judge their own actions and the way their actions are judged by the official authorities. The law never covers all the areas of human activities, and in these gaps regular people manage to control certain institutions, knowledge and the use of landscapes themselves. In a discussion of the northern Baikal area, I employ the term ‘free spaces’, that describes the weakening of external control over the sphere of activities which are essential for local people's survival. This lessening of control has led people to regulate the fishing situation locally, resulting in many violations of fishing laws not being registered in official documents. The purpose of this paper is to to discuss a case of ‘free spaces’ in the post-Soviet Evenki village, with particular focus upon the village's non-compliance with official fishery regulations. This article investigates the reasons for, and the social mechanisms guiding, non-compliant behaviour in a northern Baikal Evenki village. It argues that non-compliance with fishery regulations should be interpreted within the context of local mechanisms of social control, market relations, reciprocity and cooperation.
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Wang, Mingyuan, and Lubin Hang. "Research and application of variable DOF compliant five-bar mechanism based on novel compliant torsion joint in vehicle side door latch." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 234, no. 19 (2020): 3789–808. http://dx.doi.org/10.1177/0954406220917423.
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In this paper, a novel compliant joint with torsion spring (CJTS) is proposed in order to realize the power release (Note: The “power release” feature means that the closure system with a latch assembly including a pawl-ratchet release mechanism is controlled by at least one electric actuator.) feature of the vehicle side door latch. A new type of variable degree of freedom (DOF) compliant five-bar mechanism (VDCM) based on the novel compliant joint is constructed. The novel compliant mechanism is characterized by multiple motion modes of planar five-bar mechanism and four-joint, crank-shaper, crank-oscillating block mechanism. These motion modes can be switched through the different choices of driving joints and limiting stoppers. This compliant mechanism is effectively implanted into a vehicle side door latch as a sub-branch to perform power release function. The force-adaptive characteristic of the VDCM ensures compatibility with extant manual release branches. Drifting displacement of the CJTS’s torsion spring rotation center in the groove is proposed as a compliant index to describe the compatibility and force-adaptive characteristics under various working modes. The relationship between torsion spring stiffness and mechanism characteristic point motion trajectory or position recovery time duration or motion accuracy is studied. The results show that the introduction of compatibility and force-adaptive characteristics is able to reduce the shaking forces exerted on the mechanism frame. The shaking forces will be further reduced by changing equivalent mass center position of the component. Furthermore, the practicability of the novel compliant mechanism is experimentally validated on the force-displacement test platform. The work in this paper provides a reference for the multi-mode motion mechanical design in a confined space of the latch.
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Chen, Xiaodong, Zilong Deng, Siya Hu, Xingjun Gao, and Jinhai Gao. "Research on three-stage amplified compliant mechanism-based piezo-driven microgripper." Advances in Mechanical Engineering 12, no. 3 (2020): 168781402091147. http://dx.doi.org/10.1177/1687814020911470.
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The microgripper based on the principle of lever amplification is easy to realize; however, the theoretical amplification factor is limited by the space size and the structure is not compact enough. The microgripper based on the triangular amplification principle has a compact structure and high amplification factor, but it is not conducive to miniaturization design. Considering compactness, parallel clamping, high magnification, and miniaturization design, a three-stage amplifier consisting of a semi-rhombic amplifier and lever amplifiers is designed. To begin with, the theoretical amplification ratio and the relationship between input variables and output variables are calculated by energy method. Furthermore, the finite element analysis software is used to optimize the structural parameters and analyze the performance of the model. Lastly, the experimental verification is carried out. At 150 V of driving voltage, the maximum output displacement was 530mm, and the actual magnification was 24 times. Microparts can be gripped in parallel and stably, which confirms the validity of the design.
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Li, Haiyang, and Guangbo Hao. "Position-Space-Based Design of a Symmetric Spatial Translational Compliant Mechanism for Micro-/Nano-Manipulation." Micromachines 9, no. 4 (2018): 189. http://dx.doi.org/10.3390/mi9040189.
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Hurova, Anna, and Maria Kirpachova. "State regulation of space activity by using Blockchain." Yearly journal of scientific articles “Pravova derzhava”, no. 32 (2021): 288–96. http://dx.doi.org/10.33663/0869-2491-2021-32-288-296.
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This research is aimed at detecting legal and organizational requirements for the Blockchain application in State regulation of space activity. The most precise attention is focused on considering the compliance with the space authorization requirements, ensuring the registration of space objects and the implementation of foreign trade agreements within the space sector of the economy. The research is based on results of the previous in-depth study conducted by the authors, which was dedicated to the legal nature of the DLT (distributed ledger technologies), and in particular its most popular example Blockchain, the basic elements and models of the technology, the main spheres of its application in the framework of space activity in order to guarantee realization of rights and compliance with obligations of public and private space actors in the process of conducting the outer space activities, as well as legislative innovations to regulate the utilization of the Blockchain in different countries, as well as international standards and practices and promising legal mechanisms. Thus, the authors created logical preconditions to cover in this publication the prospects of state regulation of space activities in Ukraine using the Blockchain technology. The authors consider usage of different types of Blockchain ledgers (public ledger with authorized access and with/without special validator) to implement different tasks in the process of regulating space activities, such as guaranteeing fulfillment of conditions of foreign economic agreements on the basis of smart contracts concluded between business entities and for maintaining the state register of space objects. The research proposes several scenarios that are acceptable both in terms of technical characteristics of Blochchain and legal requirements under which a number of central authorities can exercise their powers to regulate space activities using distributed ledger technologies. In addition, the study demonstrates an effective mechanism for ensuring the allocation of responsibility for the registration of space objects between the owners of the launch vehicle and payload to prevent situations when the spacecraft remains unregistered in orbit as a result of non-compliance with contractual obligations or non-inclusion of certain clauses in such agreements. The model agreements between Ukrainian and foreign space actors are proposed to be implemented by governmental institutions and used as a preventing instrument, according to which a conflict of laws can be solved and the state responsible for registering space objects in the Blockchain Network can be defined.
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Han, Yan, Jiawen Shan, Meng Wang, and Guang Yang. "Optimization design and evaluation of parking route based on automatic assignment mechanism of parking lot." Advances in Mechanical Engineering 9, no. 7 (2017): 168781401771241. http://dx.doi.org/10.1177/1687814017712416.
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The congestion causes of parking lot were analyzed with causal chain method and a questionnaire about individual demand of parking users was carried out. The results show that more than 90% of the users hope parking spaces can be automatically assigned to them when it’s difficult to find a parking space. The layout principles of WiFi in parking lot were provided. The automatic assignment mechanism of parking lot was given considering the individual demand of parking users and the avoidance of traffic conflicts. Some attribute decision factors such as lane occupancy conditions, travel distance, walking distance, and the occupancy situation of parking space on both sides were selected and optimal parking lot assignment model was established. Optimal paths were calculated through Dijkstra algorithm, and the information about the assignment location and path was sent to the drivers’ cell phones. The driver’s compliance was evaluated by comparing the driver’s parking trajectory with system recommended path. Finally, a large parking lot in Beijing was taken as an example. The results can offer constructive suggestions on parking route design and parking assignment mechanism, which can make the use of the limited parking resources more effectively.
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Ciocarlie, M., and P. Allen. "A constrained optimization framework for compliant underactuated grasping." Mechanical Sciences 2, no. 1 (2011): 17–26. http://dx.doi.org/10.5194/ms-2-17-2011.
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Abstract. This study focuses on the design and analysis of underactuated robotic hands that use tendons and compliant joints to enable passive mechanical adaptation during grasping tasks. We use a quasistatic equilibrium formulation to predict the stability of a given grasp. This method is then used as the inner loop of an optimization algorithm that can find a set of actuation mechanism parameters that optimize the stability measure for an entire set of grasps. We discuss two possible approaches to design optimization using this framework, one using exhaustive search over the parameter space, and the other using a simplified gripper construction to cast the problem to a form that is directly solvable using well-established optimization methods. Computations are performed in 3-D, allow arbitrary geometry of the grasped objects and take into account frictional constraints. This paper was presented at the IFToMM/ASME International Workshop on Underactuated Grasping (UG2010), 19 August 2010, Montréal, Canada.
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Tsujita, Katsuyoshi, Kazuo Tsuchiya, and Yousuke Kawano. "Force Control of a Space Manipulator." Journal of Robotics and Mechatronics 12, no. 4 (2000): 351–55. http://dx.doi.org/10.20965/jrm.2000.p0351.
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This paper deals with the force control of a space manipulator for a sample-return mission. There are two difficulties in force control of this class of space manipulator: One is that a space robot has no fixed point in space and moves when its manipulator exerts force on the environment. The other is that physical properties of the environment on which the manipulator exerts force are not well known. In order to overcome these difficulties, a hierarchical controller is proposed in this paper. The controller manages attitude control of the main body and force control of the manipulator. The end effector is attached to the manipulator by a passive compliance mechanism. The performance of the proposed controller is verified by numerical simulations and hardware experiments.
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Jandaghi Shahi, Vahid, and Abolfazl Masoumi. "Integration of in-plane and out-of-plane dimensional variation in multi-station assembly process for automotive body assembly." Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering 234, no. 6 (2019): 1690–702. http://dx.doi.org/10.1177/0954407019889455.
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Automotive body assembly systems contain multiple operations in multi-station processes. One of the most critical challenges for such manufacturing systems is dimensional quality, which is affected by the accumulation and propagation of variation caused by manufacturing imperfections. However, sheet metal part compliancy behavior makes the variation modeling method extremely intricate when both rigid (in-plane) and compliant (out-of-plane) variations are considered. This paper develops a more accurate variation propagation model to describe dimensional variation of sheet metal assembly in multi-station assembly system through involving both the variation types simultaneously as well as the impacts of assembly operations on each other. In this methodology, three sources of deviations—non-ideal parts, fixture errors, and assembly operations effects—are taken into account. The variation generated in every assembly operation (placing, clamping, fastening, and releasing steps) and the variation propagation through station-to-station interaction (repositioning) are analyzed by the transfer function mechanism. In the in-plane direction, the stream of variation analysis is adopted to obtain the rigid transfer function to describe the position and orientation relationships between part and assembly element errors. For the simulation of part deformation during the assembly process in the out-of-plane direction, the compliant transfer functions are extracted by variation response methodology. A nested state space model is used to integrate the overall assembly variation by updating part geometry after each assembly operation. The capability of proposed method is illustrated through a case study on an automotive body side assembly process.
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Józsa, T. I., E. Balaras, M. Kashtalyan, A. G. L. Borthwick, and I. M. Viola. "Active and passive in-plane wall fluctuations in turbulent channel flows." Journal of Fluid Mechanics 866 (March 18, 2019): 689–720. http://dx.doi.org/10.1017/jfm.2019.145.
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Compliant walls offer the tantalising possibility of passive flow control. This paper examines the mechanics of compliant surfaces driven by wall shear stresses, with solely in-plane velocity response. We present direct numerical simulations of turbulent channel flows at low ($Re_{\unicode[STIX]{x1D70F}}\approx 180$) and intermediate ($Re_{\unicode[STIX]{x1D70F}}\approx 1000$) Reynolds numbers. In-plane spanwise and streamwise active controls proposed by Choi et al. (J. Fluid Mech., vol. 262, 1994, pp. 75–110) are revisited in order to characterise beneficial wall fluctuations. An analytical framework is then used to map the parameter space of the proposed compliant surfaces. The direct numerical simulations show that large-scale passive streamwise wall fluctuations can reduce friction drag by at least $3.7\pm 1\,\%$, whereas even small-scale passive spanwise wall motions lead to considerable drag penalty. It is found that a well-designed compliant wall can theoretically exploit the drag-reduction mechanism of an active control; this may help advance the development of practical active and passive control strategies for turbulent friction drag reduction.
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Okunev, I. Y., D. V. Basova, and M. I. Tislenko. "The Construction of Identities in Space Inversion (the Case of Blagoveshensk and Chei-Che)." MGIMO Review of International Relations, no. 6(45) (December 28, 2015): 86–92. http://dx.doi.org/10.24833/2071-8160-2015-6-45-86-92.
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Abstract: The article represents a collective research of space identities at the Russian-Chinese border. The authors analyze the space configuration formed at the frontier of Blagoveshensk and Chei-Che regarding it as a social construction. It was an attempt to define the mechanisms of creating space identity at the flexible border marked by fluctuations of economic, political and cultural flows. There is a case of the Chinese town Chei-Che which is more open towards a Russian influence as well as to a deeper integration with the Russian side. Besides, there is a case of Blagoveshensk and its residents’ perception of their Chinese “neighbor”. Two major spatial bases of stateness are traditionally singled out: nation-building and threats to security or, in other words, labeling mental boundaries of community “Us” and actualizing “Others”. Threats to security or, rather, a discourse on them, form “Others” image, on the opposition to which is based nation and its geopolitical code. Existing stable centre-peripheral relations in each country put some thought about the third state-building mechanism - internal “Other”. Interregional differentiation within a state through establishing and maintaining the internal mental boundaries between centre and periphery comprises a mechanism to identify territories which need support to continue to act in compliance with national norms and thereof to facilitate stateness. Russian history could be interpreted as a periodic artificial reproduction of semi-periphery which sets the mental boundaries of internal “Other”. Suburban colonized territories which created an attractive image of Russian state in other territories’ eyes and were funded to the detriment of Russian internal regions became semi-periphery. The research conclusions derive from series field research made in two-cities, during which some sociological and qualitative methods were used. The authors make a conclusion that Blagoveshensk and Chei-Che have two different patterns of space identities determined by official discourse and ordinary perception.
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Prasad, J., and A. R. Diaz. "Synthesis of Bistable Periodic Structures Using Topology Optimization and a Genetic Algorithm." Journal of Mechanical Design 128, no. 6 (2005): 1298–306. http://dx.doi.org/10.1115/1.2338576.
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A formulation for the automatic synthesis of two-dimensional bistable, compliant periodic structures is presented, based on standard methods for topology optimization. The design space is parametrized using nonlinear beam elements and a ground structure approach. A performance criterion is suggested, based on characteristics of the load-deformation curve of the compliant structure. A genetic algorithm is used to find candidate solutions. A numerical implementation of this methodology is discussed and illustrated using simple examples.
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Formica, Domenico, Loredana Zollo, and Eugenio Guglielmelli. "Torque-Dependent Compliance Control in the Joint Space for Robot-Mediated Motor Therapy." Journal of Dynamic Systems, Measurement, and Control 128, no. 1 (2005): 152–58. http://dx.doi.org/10.1115/1.2173009.
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This paper is focused on the design of interaction control of robotic machines for rehabilitative motor therapy of the upper limb. The control approach tries to address requirements deriving from the application field and adopts a bioinspired approach for regulating robot behavior in the interaction with the patient. An inner-outer loop control scheme is proposed. In order to tune the level of force and improve robot adaptability in the interaction with the patient, a classical outer force control loop is used. For the inner loop, a novel control law for low-level tuning of robot compliance is introduced, that is borrowed from studies on the biological mechanisms for regulating the elastic properties of the human arm. A dedicated simulation tool, which models the dynamics of an operational robotic machine interacting with a human subject, has been developed. Validation of basic adaptability and safety requirements of the control scheme is carried out in simple tasks, e.g., reaching and contact/noncontact transitions, as well as in simulated situations of typical motor exercises. In particular, the simulation tests demonstrate the adaptive capabilities of the proposed control schemes, e.g., in counterbalancing patient incorrect movements related to the various levels of disability. Moreover, preliminar experimental tests carried out on a real robotic system demonstrated the possibility of using the proposed approach for guaranteeing safe interaction with the patient.
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Evrensel, C. A., and A. Kalnins. "Response of a Compliant Slab to Viscous Incompressible Fluid Flow." Journal of Applied Mechanics 55, no. 3 (1988): 660–66. http://dx.doi.org/10.1115/1.3125845.
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The interaction of a compliant slab and the flow of a viscous fluid is explored theoretically. Both laminar and turbulent boundary-layer flow cases are considered. The slab is treated as an infinite, elastic or viscoelastic solid of finite thickness, bonded to a rigid half-space. The two media are coupled through stresses and velocities, in both tangential and normal directions, on the deformed surface of the slab. The proposed mathematical model is used to predict the appearance of unstable surface waves of the coating. According to the model, instabilities of a highly viscoelastic slab originate in the form of waves with phase speeds at about 2.3 percent of the flow velocity while the wave speed for a slab with zero to moderate viscosity is in the range of 50–60 percent of the flow velocity, which confirms previous experimental results. The predicted onset velocities of slow propagating waves for turbulent flow over plastisol gel are within 10 percent of those observed experimentally.
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Heiss, John D., Nicholas Patronas, Hetty L. DeVroom, et al. "Elucidating the pathophysiology of syringomyelia." Journal of Neurosurgery 91, no. 4 (1999): 553–62. http://dx.doi.org/10.3171/jns.1999.91.4.0553.
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Object. Syringomyelia causes progressive myelopathy. Most patients with syringomyelia have a Chiari I malformation of the cerebellar tonsils. Determination of the pathophysiological mechanisms underlying the progression of syringomyelia associated with the Chiari I malformation should improve strategies to halt progression of myelopathy.Methods. The authors prospectively studied 20 adult patients with both Chiari I malformation and symptomatic syringomyelia. Testing before surgery included the following: clinical examination; evaluation of anatomy by using T1-weighted magnetic resonance (MR) imaging; evaluation of the syrinx and cerebrospinal fluid (CSF) velocity and flow by using phase-contrast cine MR imaging; and evaluation of lumbar and cervical subarachnoid pressure at rest, during the Valsalva maneuver, during jugular compression, and following removal of CSF (CSF compliance measurement). During surgery, cardiac-gated ultrasonography and pressure measurements were obtained from the intracranial, cervical subarachnoid, and lumbar intrathecal spaces and syrinx. Six months after surgery, clinical examinations, MR imaging studies, and CSF pressure recordings were repeated. Clinical examinations and MR imaging studies were repeated annually. For comparison, 18 healthy volunteers underwent T1-weighted MR imaging, cine MR imaging, and cervical and lumbar subarachnoid pressure testing.Compared with healthy volunteers, before surgery, the patients had decreased anteroposterior diameters of the ventral and dorsal CSF spaces at the foramen magnum. In patients, CSF velocity at the foramen magnum was increased, but CSF flow was reduced. Transmission of intracranial pressure across the foramen magnum to the spinal subarachnoid space in response to jugular compression was partially obstructed. Spinal CSF compliance was reduced, whereas cervical subarachnoid pressure and pulse pressure were increased. Syrinx fluid flowed inferiorly during systole and superiorly during diastole on cine MR imaging. At surgery, the cerebellar tonsils abruptly descended during systole and ascended during diastole, and the upper pole of the syrinx contracted in a manner synchronous with tonsillar descent and with the peak systolic cervical subarachnoid pressure wave. Following surgery, the diameter of the CSF passages at the foramen magnum increased compared with preoperative values, and the maximum flow rate of CSF across the foramen magnum during systole increased. Transmission of pressure across the foramen magnum to the spinal subarachnoid space in response to jugular compression was normal and cervical subarachnoid mean pressure and pulse pressure decreased to normal. The maximum syrinx diameter decreased on MR imaging in all patients. Cine MR imaging documented reduced velocity and flow of the syrinx fluid. Clinical symptoms and signs improved or remained stable in all patients, and the tonsils resumed a normal shape.Conclusions. The progression of syringomyelia associated with Chiari I malformation is produced by the action of the cerebellar tonsils, which partially occlude the subarachnoid space at the foramen magnum and act as a piston on the partially enclosed spinal subarachnoid space. This creates enlarged cervical subarachnoid pressure waves that compress the spinal cord from without, not from within, and propagate syrinx fluid caudally with each heartbeat, which leads to syrinx progression. The disappearance of the abnormal shape and position of the tonsils after simple decompressive extraarachnoidal surgery suggests that the Chiari I malformation of the cerebellar tonsils is acquired, not congenital. Surgery limited to suboccipital craniectomy, C-1 laminectomy, and duraplasty eliminates this mechanism and eliminates syringomyelia and its progression without the risk of more invasive procedures.
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Dahlen, Nicole. "Schwerelos und gut gelagert." Konstruktion 71, S2 (2019): 28–31. http://dx.doi.org/10.37544/0720-5953-2019-s2-28.
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Viele Experimente, aber keine in puncto Sicherheit: Dass die Systeme der Internationalen Raumstation vor allem im Außeneinsatz reibungslos funktionieren, ist überlebenswichtig für Astronauten. Der für die Zusammenarbeit mit dem Menschen ausgelegte CAESAR – Compliant Assistance and Exploration SpAce Robot – wurde deswegen mit Dünnringlagern von Rodriguez ausgestattet.
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Portier, Frédéric, Carlos De Minteguiaga, Patrice Tran Ba Huy, Emmanuel Racy, and Philippe Herman. "Spontaneous Intracranial Hypotension: A Rare Cause of Labyrinthine Hydrops." Annals of Otology, Rhinology & Laryngology 111, no. 9 (2002): 817–20. http://dx.doi.org/10.1177/000348940211100910.
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Spontaneous intracranial hypotension should be considered as a possible cause of cochlear hydrops. We report a case of unilateral hearing loss attributed to spontaneous intracranial hypotension on the basis of characteristic abnormalities seen on magnetic resonance imaging. The diagnostic gold standards for intracranial hypotension are lumbar measurement of cerebrospinal fluid pressure and magnetic resonance imaging. The usual treatment is an autologous blood injection into the peridural spaces. The mechanism of hearing loss is thought to involve secondary perilymph depression due to a patent cochlear aqueduct. This perilymph depression would induce a compensatory expansion of the endolymphatic compartment, with a subsequent decrease in basilar or Reissner's membrane compliance. Endolymphatic hydrops can occur in the course of intracranial hypotension, and not only because of abnormal endolymph production or resorption. Hydrops can thus be classified into 1) syndromes of endolymphatic origin and 2) syndromes of perilymphatic origin, in which loss of perilymph induces compensatory expansion of the endolymphatic space.
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Hasheminejad, M., and T. L. Geers. "The Accuracy of Doubly Asymptotic Approximations for an Acoustic Half-Space." Journal of Vibration and Acoustics 114, no. 4 (1992): 555–63. http://dx.doi.org/10.1115/1.2930298.
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The accuracy of doubly asymptotic approximations (DAAs) for acoustic half-space problems is assessed by examining their performance for a canonical problem in bispherical coordinates. Exact specific acoustic impedance curves for axisymmetric modal vibrations of a spherical surface near a planar boundary are generated, and corresponding curves based on the first-order DAA and the curvature-corrected DAA are compared with their exact counterparts. The comparisons show that the curvature-corrected DAA is substantially more accurate than the first-order DAA. Also, the curvature-corrected DAA is found to be satisfactory for broad-band excitations regardless of the sphere’s proximity to a compliant (zero-pressure) surface; for a rigid surface, the approximation is satisfactory only if the sphere is located at least one diameter away from the boundary.
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Kapanga, Kasongo M. "Legitimizing the invented Congolese space: The gaze from within in early Congolese fiction." Tydskrif vir Letterkunde 46, no. 1 (2017): 28–42. http://dx.doi.org/10.17159/2309-9070/tvl.v.46i1.3462.
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Postcolonial discourses describe colonization as a process of invention to impose the will of a conquering West on “backward” societies. The will to power conjugated with the need for raw materials served as the main catalysts. They put side by side a hegemonic intruder bent on duplicating itself, and a powerless and compliant native unable to react to the blitz of transformations. Hence, the master/slave or father/child relationships that describe the colonial framework. The task is to interrogate these generally accepted assumptions and binary oppositions. Although marginalized, the Congolese native was unwilling to become an object for the colonizer’s gaze. In fact, the inability to expel the “invader” did not prevent the creation of legitimacies out of what was precipitously brought in. This mechanism of transformation is perceptible in Paul Lomami Tchibamba’s novel Ngando (1948), the object of this study. Ngando’s imagined colonial city stands out as a site of contrasts and contradictions. However, the duplicated model shows the “transformability” of the new space into “normalcy” by a subversive native.
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Heiss, John D., Nicholas Patronas, Hetty L. DeVroom, et al. "Elucidating the pathophysiology of syringomyelia." Neurosurgical Focus 7, no. 2 (1999): E1. http://dx.doi.org/10.3171/foc.1999.7.2.1.
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Object Syringomyelia causes progressive myelopathy. Most patients with syringomyelia have a Chiari I malformation of the cerebellar tonsils. Determination of the pathophysiological mechanisms underlying the progression of syringomyelia associated with the Chiari I malformation should improve strategies to halt progression of myelopathy. Methods The authors prospectively studied 20 adult patients with both Chiari I malformation and symptomatic syringomyelia. Testing before surgery included the following: clinical examination; evaluation of anatomy by using T1-weighted magnetic resonance (MR) imaging; evaluation of the syrinx and cerebrospinal fluid (CSF) velocity and flow by using phase-contrast cine MR imaging; and evaluation of lumbar and cervical subarachnoid pressure at rest, during the Valsalva maneuver, during jugular compression, and following removal of CSF (CSF compliance measurement). During surgery, cardiac-gated ultrasonography and pressure measurements were obtained from the intracranial, cervical subarachnoid, and lumbar intrathecal spaces and syrinx. Six months after surgery, clinical examinations, MR imaging studies, and CSF pressure recordings were repeated. Clinical examinations and MR imaging studies were repeated annually. For comparison, 18 healthy volunteers underwent T1-weighted MR imaging, cine MR imaging, and cervical and lumbar subarachnoid pressure testing. Compared with healthy volunteers, before surgery, the patients had decreased anteroposterior diameters of the ventral and dorsal CSF spaces at the foramen magnum. In patients, CSF velocity at the foramen magnum was increased, but CSF flow was reduced. Transmission of intracranial pressure across the foramen magnum to the spinal subarachnoid space in response to jugular compression was partially obstructed. Spinal CSF compliance was reduced, whereas cervical subarachnoid pressure and pulse pressure were increased. Syrinx fluid flowed inferiorly during systole and superiorly during diastole on cine MR imaging. At surgery, the cerebellar tonsils abruptly descended during systole and ascended during diastole, and the upper pole of the syrinx contracted in a manner synchronous with tonsillar descent and with the peak systolic cervical subarachnoid pressure wave. Following surgery, the diameter of the CSF passages at the foramen magnum increased compared with preoperative values, and the maximum flow rate of CSF across the foramen magnum during systole increased. Transmission of pressure across the foramen magnum to the spinal subarachnoid space in response to jugular compression was normal and cervical subarachnoid mean pressuree and pulse pressure decreased to normal. The maximum syrinx diameter decreased on MR imaging in all patients. Cine MR imaging documented reduced velocity and flow of the syrinx fluid. Clinical symptoms and signs improved or remained stable in all patients, and the tonsils resumed a normal shape. Conclusions The progression of syringomyelia associated with Chiari I malformation is produced by the action of the cerebellar tonsils, which partially occlude the subarachnoid space at the foramen magnum and act as a piston on the partially enclosed spinal subarachnoid space. This creates enlarged cervical subarachnoid pressure waves that compress the spinal cord from without, not from within, and propagate syrinx fluid caudally with each heartbeat, which leads to syrinx progression. The disappearance of the abnormal shape and position of the tonsils after simple decompressive extraarachnoidal surgery suggests that the Chiari I malformation of the cerebellar tonsils is acquired, not congenital. Surgery limited to suboccipital craniectomy, C-1 laminectomy, and duraplasty eliminates this mechanism and eliminates syringomyelia and its progression without the risk of more invasive procedures.
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Prime, M. B., and I. Finnie. "Surface Strains Due to Face Loading of a Slot in a Layered Half-Space." Journal of Engineering Materials and Technology 118, no. 3 (1996): 410–18. http://dx.doi.org/10.1115/1.2806828.
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A solution is presented that will allow the compliance method for residual stress measurement to be applied to layered materials. The solution is for surface strains due to arbitrary normal stress loading on the faces of a slot in a layered half-space. The materials are homogeneous isotropic elastic with different elastic constants and the slot may penetrate into the substrate. The solution is accomplished using the body force method and the solution for a point force in two bonded half spaces. The results indicate that, for residual stress measurement, the effects of the substrate properties are significant for materials with elastic moduli differing by 50 percent or more when the slot penetrates to at least one-half of the layer thickness.
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Lukic, Nikola, and Petar B. Petrovic. "Complementary projector for null-space stiffness control of redundant assembly robot arm." Assembly Automation 39, no. 4 (2019): 696–714. http://dx.doi.org/10.1108/aa-10-2018-0163.
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Purpose Stiffness control of redundant robot arm, aimed at using extra degrees of freedom (DoF) to shape the robot tool center point (TCP) elastomechanical behavior to be consistent with the essential requirements needed for a successful part mating process, i.e., to mimic part supporting mechanism with selective quasi-isotropic compliance (Remote Center of Compliance – RCC), with additional properties of inherent flexibility. Design/methodology/approach Theoretical analysis and synthesis of the complementary projector for null-space stiffness control of kinematically redundant robot arm. Practical feasibility of the proposed approach was proven by extensive computer simulations and physical experiments, based on commercially available 7 DoF SIA 10 F Yaskawa articulated robot arm, equipped with the open-architecture control system, system for generating excitation force, dedicated sensory system for displacement measurement and a system for real-time acquisition of sensory data. Findings Simulation experiments demonstrated convergence and stability of the proposed complementary projector. Physical experiments demonstrated that the proposed complementary projector can be implemented on the commercially available anthropomorphic redundant arm upgraded with open-architecture control system and that this projector has the capacity to efficiently affect the task-space TCP stiffness of the robot arm, with a satisfactory degree of consistency with the behavior obtained in the simulation experiments. Originality/value A novel complementary projector was synthesized based on the adopted objective function. Practical verification was conducted using computer simulations and physical experiments. For the needs of physical experiments, an adequate open-architecture control system was developed and upgraded through the implementation of the proposed complementary projector and an adequate system for generating excitation and measuring displacement of the robot TCP. Experiments demonstrated that the proposed complementary projector for null-space stiffness control is capable of producing the task-space TCP stiffness, which can satisfy the essential requirements needed for a successful part-mating process, thus allowing the redundant robot arm to mimic the RCC supporting mechanism behavior in a programmable manner.
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Morard, Adrien, Jean-Christophe Riou, and Gabriel Pares. "Flip chip reliability and intermetallic compounds for SIP module." International Symposium on Microelectronics 2018, no. 1 (2018): 000029–36. http://dx.doi.org/10.4071/2380-4505-2018.1.000029.
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Abstract In the aeronautical field, the electronic integration roadmaps show that the weight and the volume dedicated to on-board electronics must be reduced by a factor of 4 to 10 compared to the existing ones for the most recurrent functions in the next years. This work is an opening to new technological solutions to increase our ability to save space while improving the overall reliability of the system. The first part of this work is dedicated to the study of “system in package” (SiP) solutions based on different substrates, namely organic or silicon. Generally speaking a SIP is composed by several active and passive components stacked on an interposer. Benchmarks done by our laboratory have demonstrated that in terms of substrate, embedded die technology leads to several advantages compared to 3D TSV or TGV based packaging approaches. The benefits provided by this substrate is the possibility to embed some surface mount technologies (SMT), some bare chips or some integrated passives devices (IPD) banks directly above or below the stacked active components. This way, top and bottom surface of the substrate can be used to integrate several heterogeneous dies side by side while using low profile flip-chip assemblies on the C4 side. Finally, in this kind of 3D architecture, this embedded technology enable a gain of integration, without using costly TSV connections. Substrates of high quality allow a reduction of I/Os interconnection pitches leading to very aggressive integration down to 50μm. Secondly, a 3D stack with 3 levels of components, as described above, leads to 2 or 3 REACH compliant sequential assembly processes, depending of the needs. In order to consider all the solutions for an optimized overall integration with high reliability, this work focuse on the study one simple SIP which includes the top die assembled by flip-chip. For the flip chip hybridization on organic interposers copper pillars technologies will be studied. The objective is to understand in depth the processes and to obtain information on the reliability aspect after thermal cycling stress of the flip chip assembly. Thirdly, we built many silicon test chips with different characteristics with a dedicated daisy chain test vehicle. The different parameters are: chip's thicknesses (50 to 200 μm), chip's sizes (2 to 8 mm), bump structures (diameter), the pitches of the interconnection (from 50 to 250 μm) and the number of interconnection rows. Designs were chosen in order to fit real operational configurations. Moreover, these configurations are interesting to build a comprehensive model in order to understand the failure mechanisms. These chips are then stacked by flip chip on the silicon and on the organic substrate. We are also designing the both configurations of substrates. Only the production of the organics part is outsourced. Fourth, for all assemblies thermos-cycling test results will be evaluated with thermo mechanical simulations done by finite elements. 3D models will take into account the different geometries in order to understand and quantify the various key parameters. The analysis will mainly focus on 3D interconnections. Design rules based on the results will be derivated. The aim is to obtain dimensional criteria based on stress versus deformation responses. Lastly intermetallic formation will be evaluated using EBSD analysis to obtain better understanding of copper pillar failures for this specific bumps size. Issued information's will be exploited for designing the future functional SIP. The ultimate goal of this work is finally to define mechanical design rules that can then be used in functional SiP modules.