Hierarchical Estimation and Segmentation of Dense Motion Fields

In this paper we present a comprehensive energy-based framework for the estimation and the segmentation of the apparent motion in image sequences. The robust cost functions and the associated hierarchical minimization techniques that we propose mix efficiently non-parametric (dense) representations, local interacting parametric representations, and global non-interacting parametric representations related to a partition into regions. Experimental comparisons, both on synthetic and real images, demonstrate the merit of the approach on different types of photometric and kinematic contents ranging from moving rigid objects to moving fluids.     

The Applications of Wavelets in Hierarchical Representations and Smoothing of Curves and Surfaces

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复杂场景中动态简化层次的构造

多细节层次描述（简称ＬｏＤ）是实时绘制复杂几何场景的一种有效工具。基于层次结构的动态简化方法能够根据视点的变化，实时连续地转换场景细节模型。本文提出了一种改进的动态网格简化框架，它利用顶点映射机制支持不同细节层次之间的快速连续转换，同时还给出了建立和维护复杂场景动态简化层次结构的方法。     

A transform technique for time-varying linear hybrid systems

A computationally oriented transform technique for the analysis of time-varying linear systems involving both discrete-time (i.e., sampled-data) variables and continuous-time variables is presented in this paper. Finite-dimensional representations are described for the various linear operators involved, and methods for obtaining singular-value decompositions of these operators are given. The three parts of the singular-value decomposition are analogous to the direct transform, transfer function, and inverse transform of Laplace and Fourier transforms, and offer analogous insights into analysis and synthesis problems. An example is included to illustrate the analysis procedures.     

Topological and dimensional synthesis of planar linkages for multiple kinematic tasks

This paper presents the combined use of two systematic methods for the synthesis of planar linkage mechanisms satisfying multiple kinematic tasks. First, a Graph Theory-based method is used to exhaustively enumerate the topological alternatives for a given problem. Then each feasible alternative is automatically dimensioned using the Precision Position Method; this computation includes space and design constraints. The existing methods to synthesize multiple tasks solve, in sequence, a decomposition of the problem into single kinematic tasks. The task decomposition and the topology selection for each task are usually performed by hand. This process leads to topologies with a repeated pattern and could lead to ignoring potentially desirable topologies. This paper analyzes a design strategy for the simultaneous solution of multiple kinematic tasks. This strategy has two advantages: (i) it eliminates the need for task decomposition, and (ii) it allows the exhaustive exploration of all non-isomorphic topologies up to a defined number of links. An example of simultaneous synthesis for a double rigid-body guidance task with application to a flap-tab mechanism is shown to illustrate the methodology.     

The virtual feedback problem in hierarchical representations of combinational circuits

Orders of magnitude of space and time can be saved if hierarchical algorithms are used for automatic synthesis and analysis of regular VLSI circuits. When we tried to apply this technique to compiled simulation of large regular combinational circuits, we observed that hierarchical representations of acyclic circuits often contain cycles. In this paper we study the question of whether this undesired property is necessary or not. We prove, that there are combinational circuits, which have a succinct cyclic hierarchical representation, but where each acyclic hierarchical representation is large. This negative result may be weakened, if we allow the circuits structure to be changed but not its behavior. We also discuss the effect of these observations on hierarchical simulation techniques and the complexity of pragmatic approaches such as the construction of a smallest acyclic refinement of a hierarchical representation.This work was supported by Deutsche Forschungsgemeinschaft under contract SFB 124 B1     

A CMAC neural-network-based algorithm for the kinematic control of a walking machine

In this paper a hierarchical, neural network control architecture of a walking machine is proposed. The neural network is based on the theory of the Cerebellum Model Articulation Controller (CMAC) which is a neuromuscular control system. Some preliminary studies of kinematic control and gait synthesis are presented to demonstrate the effectiveness of the CMAC neural network. After having been trained to learn the multivariable, nonlinear relationships of the leg kinematics and gaits, CMAC is utilized to perform feedforward kinematic control of a quadruped in straight-line walking and step climbing. Simulation examples are provided and discussed. This algorithm can be extended to control other highly nonlinear processes which are hierarchical in nature and cannot be modeled by mathematical equations.     

PPRRRP和RRRPU肩关节康复外骨骼机构运动性能的分析比较

基于外骨骼机构的构型综合和优选原则,提出PPRRRP和RRRPU两种外骨骼构型.在优选的构型中,通过在人机连接处引入被动关节,使外骨骼机构和人体上臂形成的人机闭链转化为3-DOF（自由度）运动学恰约束系统,实现人机运动学相容.从人机闭链整体的角度,分别建立PPRRRP和RRRPU人机闭链运动学模型,通过对被动关节的合理分解及运动学特征分析,推导其运动学约束方程,并分别求得两闭链的速度雅可比矩阵,该方法降低了人机闭链运动学分析的复杂性.通过对速度雅可比矩阵的数值仿真,在冠状面、矢状面和水平面对2种外骨骼构型进行条件数倒数、可操作度椭球以及灵巧操作速度的分析比较.结果表明：在上述3个面内,PPRRRP构型的运动灵活度、运动各向同性和速度操作灵巧性的运动学性能要优于RRRPU.在此基础上,研制了PPRRRP构型的上肢康复外骨骼样机.     

Dimensional Synthesis of Spatial Mechanisms and the Problem of Non-Assembly

In this paper a general method for dimensional synthesis of both planar and spatial mechanisms is presented. The method addresses the problem of non-assembly. A gradient based optimization algorithm is employed and the sensitivities are calculated analytically using the method of direct differentiation. A well established and general method of computational kinematics is employed, in a slightly modified variant, to avoid the problem of non-assembly. The modification consists of a minimization of the residuals of the kinematic constraint equations, rather than equating them to zero. The point-coordinate formulation is applied. Several examples are provided.     

Hierarchical Analysis of IC Artwork with User-Defined Rules

Hierarchical design rule check and component extract offer many advantages, but no single form of hierarchical analysus fits al situations. However, we will deal with hierarchical analyses which allow the user to specify how abstract representations of cells are formed, how they are checked, and how to respond if a violation is detected. This allows one analysis fits all situations. However, we will deal with hierarchical analyses which allow the user to specify how abstract representations of cells are formed, how they are checked, and how to respond if a violation is detected. This allows one analysis program (with different rules) to use the designer's hierarchy for a wide variety of analyses. Analyses that were difficult in previous schemes (cross-coupling capacitances, terminals in the center of cells, and multilayer interconnects) can now be handled hierarchically. An analysis of existing custom VLSI chips reveals how designers use hierarchy. While they commonly add geometry across hierarchical boundaries, designers rarely change the circuits of subcells?implying that hierarchical analysis is practical for a wide variery of analysis is practical for a wide variety of analyses. Cases where hiearchical analysis is not practical, limited in variety, can be handled automatically by using differemt rules depending on the cell type.     

A New Complete Hierarchical Classification Approach to Kinematic Chains

Based on structural properties and genetic isomorphism-identification approach, this paper proposes a classification scheme of kinematic structures to categorize the kinematic chains into different families, thus facilitating the optimum selection of a basic structure of a mechanism. The kinematic chain is represented by a graph at first. The genetic adaptive model for the graph isomorphism identification is developed, which includes the construction of an effective method to decrease the problem's dimensions and applying an evolutionary searching strategy. From the various invariants of the genetic adaptive model, which charaterize the specific features of a kinematic chain or a family of kinematic chains, we obtain a six-step hierarchical classification scheme. This scheme classifies together the kinematic chains having similar sub-sets of structures forming isomorphic sub-chains. An example illustrates the theory, procedure and utitlity of the hierarchical classification. The scheme reduces computing time and effort in the optimum selection of a kinematic structure from a large family of kinematic chains.     

Hierarchical design,laboratory prototype fabrication and machining tests of a novel 5-axis hybrid serial-parallel kinematic machine tool

Hybrid serial-parallel kinematic machine tool (HSPKMT) has been regarded as a promising solution for 5-axis machining in many industrial fields. A typical HSPKMT can be constructed by integrating a parallel functional module with a serial functional module. Following this way, the authors construct a novel 5-axis HSPKMT through the integration of an over constrained redundantly actuated parallel module with a stack-up serial gantry. The proposed HSPKMT can accomplish a 5-axis motion capacity with three translations and two rotations (3T2R). A hierarchical design method is proposed to facilitate the design issues of the 5-axis HSPKMT. According to the hierarchical method, a laboratory prototype is designed with a top-down strategy and then fabricated with a bottom-up strategy. An open-architecture computer numerical control (CNC) system is developed to drive the fabricated prototype. A kinematic analysis is carried out to reveal necessary kinematic properties of the proposed HSPKMT. The reachable workspace and task workspace are defined to graphically illustrate the machine's position-orientation capabilities. A workspace performance index is formulated to compare the proposed 5-axis HSPKMT with several 5-axis machine tools. Based the kinematic analysis, a 5-axis machining methodology is developed and further applied to the laboratory prototype to perform 5-axis machining tasks. The machining tests verify that the proposed novel HSPKMT possesses desirable 5-axis machining capability with the tolerance rang of ±0.05 mm. This also implies that the proposed hierarchical design method as well as the 5-axis machining methodology can be further applied to other types of HSPKMTs with minor modifications.     

The establishment of edge-based loop algebra theory of kinematic chains and its applications

Based on the edge-based array representation of loops in the topological graphs of kinematic chains, this paper first proposes three arithmetic operations of loops. Then the concept of the independent loop set as well as its determination rules is introduced, and a new structure decomposition algorithm of kinematic chains is presented. Based on the algorithm, an automatic and efficient method for rigid sub-chain detection and driving pair selection of kinematic chains is proposed. Finally, an index is proposed to assess computation complexity of kinematic analysis with respect to different driving pair selections.     

GDDT—A graphical design and documentation tool for software development

This paper describes “The Graphical Design and Documentation Tool” (GDDT), a general purpose support system for design and documentation. Self documentation and ease of use are presented as important criteria for such tools. Interactive graphics is introduced as a methodology for creating and maintaining hierarchical representations. The graphical representations of various requirements specification techniques and design tools are supported by an extended network model which supports hierarchical decomposition of structures. GDDT is proposed as a general purpose design tool which supports the most common logical constructions of both requirements specification and design methodologies and yet has a high level human interface which makes it easy to learn and use.     

Diamond Hierarchies of Arbitrary Dimension

Nested simplicial meshes generated by the simplicial bisection decomposition proposed by Maubach [ Mau95 ] have been widely used in 2D and 3D as multi-resolution models of terrains and three-dimensional scalar fields, They are an alternative to octree representation since they allow generating crack-free representations of the underlying field. On the other hand, this method generates conforming meshes only when all simplices sharing the bisection edge are subdivided concurrently. Thus, efficient representations have been proposed in 2D and 3D based on a clustering of the simplices sharing a common longest edge in what is called a diamond. These representations exploit the regularity of the vertex distribution and the diamond structure to yield an implicit encoding of the hierarchical and geometric relationships among the triangles and tetrahedra, respectively. Here, we analyze properties of d -dimensional diamonds to better understand the hierarchical and geometric relationships among the simplices generated by Maubach's bisection scheme and derive closed-form equations for the number of vertices, simplices, parents and children of each type of diamond. We exploit these properties to yield an implicit pointerless representation for d -dimensional diamonds and reduce the number of required neighbor-finding accesses from O ( d !) to O ( d ).     

Automatic layout of statecharts

Graphical notations are widely used for system specification. The usefulness of these notations depends primarily on their readability. Hence, automatic methods are needed to obtain efficient and understandable graphical representations of requirements. In this paper, we present an algorithm that automatically generates layouts of statecharts. We assume that relevant information is stored in a structure that we call a decomposition tree, and we draw the graph that models a statechart in a hierarchical fashion. Our approach excludes diagrams with inter‐level transitions. Copyright © 2001 John Wiley & Sons, Ltd.     

Hierarchical structure to winged-edge structure: a conversion algorithm

The winged-edge data structure is advantageous for traversing the topological graph of the boundary representation of a solid object. This paper presents an algorithm for converting hierarchical boundary representations into representations in the winged-edge data structure. As a result of the conversion, the adjacency relationships of geometric entities embedded in hierarchical boundary representations,-which may be evaluated through boundary evaluation on solid objects defined via Boolean set-operations, can be easily and efficiently accessed.     

面向对象表达产品族实例知识的智能化快速设计

提出了智能化快速设计系统的总体框架，描述了以层次分解树表达产品族设计模型，给出了实例知识的存储结构和检索策略规则，实现了基于产品族实例知识的快速设计方法并给出了具体应用实例。