空间机器人位姿空间分层量化建模的方法

本文首先分析了空间机器人在位姿空间的不会合可控性及其给运动规划带来的困难。在此基础上，本文提出一种适用于空间机器人的位姿空间分层量经建模方法。此方法首先对位姿空间进行了分层量化处理，然后通过定义位姿间的相邻关系而建立了位姿空间图（ＣＳＧ），并对ＣＳＧ的预点和边的碰撞情况做了规定。最后本文针对一个空间机器人模型给出一个位姿空间建模的实例和基于此建模方法的运动规划结果。     

基于位姿空间栅格扩展及变维搜索的\=机器人运动规划新策略

本文首先对机器人运动规划算法中的栅格扩展策略及次序规划法进行了探讨,并提 出了相应的改进方法,在此基础上提出了一种新的机器人运动规划策略——基于位姿空间栅 格扩展及变维空间搜索算法,该算法可有效地在复杂环境中找出无碰撞路径．     

工业机器人的工作空间综合

根据机器人工作位姿要求确定其自由度数，关节类型及排列，杆件尺寸，关节运动范围，机器人的位置等过程称为机器人的工作空间综合过程，本文侧重对已知的机器人结构提出了进行工作空间综合的优化方法。     

表征空间中的机器人分层运动规划

由于对机器人的任务要求日趋复杂和多变,如何使机器人具备灵活的配置和运动规划能力,以适应复杂任务的需求,成为了目前运动规划领域所研究的核心问题.传统的基于任务空间和配置空间的建模方法虽然在机器人运动规划领域得到了非常广泛的应用,但在用于解决复杂规划任务时无法对不可行任务进行进一步地处理.本文在表征空间模型的基础上,提出了一种分层的运动规划算法,一方面借助于表征空间维度的扩展,使对运动规划任务的描述更为灵活;另一方面通过任务层与运动层的循环交互,使生成的路径满足更高层次和更丰富的任务要求.在仿人机器人和多机器人系统上的应用结果表明了本文所提算法的有效性.     

自由飘浮空间机器人系统基座姿态调整

规划机械臂的运动以调整作为其基座的卫星的姿态，既节约姿控燃料，又可作为常规姿控系统的备份手段．首先，建立自由飘浮空间机器人系统的状态方程，其状态变量为关节角和卫星姿态角，输入变量为关节角速度．基于系统能控性理论，规划连接系统初始状态和期望状态的路径，实现了仅通过机械臂关节的运动同时控制基座姿态和机械臂关节角的目的．从理论上分析了机械臂的能量消耗，给出了使能量指标最小的近似最优算法．仿真结果表明了该方法的有效性．     

空间机器人捕获非合作目标的测量与规划方法

提出了基于立体视觉的空间机器人捕获非合作目标的测量与规划方法,包括图像处理与特征提取、3D 重构及位姿测量、自主规划与控制等．同时,还建立了一套仿真系统,可进行包括图像采集、位姿测量、追踪星 GNC、空间机器人规划与控制、航天器动力学计算等在内的闭环仿真．仿真结果验证了算法的有效性．     

机器人C-空间障碍边界建模与无碰路径规划

基于机器人与障碍实体的实际碰撞关系，通过对Ｃ－空间障碍的特性分析，定义了临界碰撞关节角，提出了基于临界碰撞关节角的Ｃ－空间障碍边界建模方法．该方法计算量小，可直接同机器人动态仿真模型相联，便于系统集成．路径搜索利用改进的Ａ＊算法，采用动态变步长并进行目标可见性测试，提高了搜索效率，并利用全局路径优化算法对路径进行了优化．仿真结果表明本文提出的算法对静态结构化环境下机器人操作机的路径规划是切实有效的．     

机器人动态位姿误差在工作空间的补偿算法

本文从机器人末端位姿的理论模型出发,结合实际得到的机器人末端位姿,应用最小二乘法理论,建立了在工作空间对机器人动态位姿误差进行补偿的有效方法.     

EMR系统机器人运动学和工作空间的分析

本文研究了EMR系统机器人的运动学和工作空间。首先对机器人的工作空间进行了分析,并提出了求解机器人末端灵活性的方法;接着解决了机器人位姿正运动学描述和逆运动学求解的问题;最后针对欠自由度的机器人结构,提出采用一组变量来描述机器人的速度运动学,避免了采用伪逆求逆速度运动学。     

CAD／CG在机器人离线编程中的应用

机器人离线编程是机器人应用的重要工具，它与ＣＡＤ／ＣＧ技术紧密相关，本文讨论ＣＡＤ／ＣＧ在我们开发的装配机器人离线编程系统ＡＲＰＳ中的应用，包括机器人世界的几何建模、运动位置的推理、碰撞检查和计算机动画。     

Consistent Schemes for Addressing Surfaces when Ray Tracing Transparent CSG Objects

Constructive Solid Geometry (CSG) defines the shape of objects, i.e. the inside and the outside regions of objects, but it does not define the material properties of the space in the interior of objects. The definition is ambiguous. There are points of space lying in several primitives, which can consist of different materials. When visualizing transparent objects this ambiguity leads to strange results, which are not consistent with the CSG modelling scheme and must therefore be eliminated. This work describes how an unambiguous model can be built by asymmetric CSG-operators and how correct refraction and shading on material boundaries can be established by separating surface properties from material properties. This separation leads to a consistent view of CSG modelling also concerning materials and surfaces. Ray tracing CSG trees and the shading model are influenced by these asymmetric operators. We introduce an applied classification scheme to handle the requirements of the new operator definition.     

Construction and optimization of CSG representations

Boundary representations (B-reps) and constructive solid geometry (CSG) are widely used representation schemes for solids. While the problem of computing a B-rep from a CSG representation is relatively well understood, the inverse problem of B-rep to CSG conversion has not been addressed in general. The ability to perform B-rep to CSG conversion has important implications for the architecture of solid modelling systems and, in addition, is of considerable theoretical interest.

The paper presents a general approach to B-rep to CSG conversion based on a partition of Euclidean space by surfaces induced from a B-rep, and on the well known fact that closed regular sets and regularized set operations form a Boolean algebra. It is shown that the conversion problem is well defined, and that the solution results in a CSG representation that is unique for a fixed set of halfspaces that serve as a ‘basis’ for the representation. The ‘basis’ set contains halfspaces induced from a B-rep plus additional non-unique separating halfspaces.

An important characteristic of B-rep to CSG conversion is the size of a resulting CSG representation. We consider minimization of CSG representations in some detail and suggest new minimization techniques.

While many important geometric and combinatorial issues remain open, a companion paper shows that the proposed approach to B-rep to CSG conversion and minimization is effective in E², In E³, an experimental system currently converts natural-quadric B-reps in PARASOLID to efficient CSG representations in PADL-2.     

面向航天任务综合仿真的想定生成系统研究

设计和实现了一个面向航天任务综合仿真的想定生成系统。目前,多数的想定生成系统都是为军事战术仿真服务,而所描述的想定系统,则是建立在航天任务综合仿真的基础上。航天任务综合仿真的想定生成系统有如下特点;首先,它支持同一概念模型向不同仿真模型的映射;其次,由于想定模型种类多样,模型之间关系复杂,想定生成系统在对多粒度模型支持以及想定的描述方法等方面也异于一般想定生成系统。首先定义了航天任务综合仿真的想定的内涵,并阐述了想定生成系统的特点。接下来给出了系统的组成结构,最后是系统实现方案及运行流程。     

A new space subdivision for ray tracing CSG solids

Ray tracing successfully creates realistic images of constructive solid geometry (CSG) solids. We describe a nonuniform space subdivision scheme that reduces both the number of ray-object intersection computations and point classifications. Our method uses the face planes of the primitives' S-bounds in a bottom-up fashion and produces a subdivision wherein the localized CSG tree in each leaf voxel is greatly minimized. The use of S-bounds in the space subdivision effectively reduces the number of intersection computations as well. The reduction of the localized CSG tree in turn further reduces the number of intersection computations and point classifications. We briefly review existing methods for ray tracing CSG solids, describe our proposed space subdivision method, discuss our implementation and compare it to Bouatouch's (1987) method, and summarize our test results     

Manufacturing applications of octrees

It is well understood that effective and comprehensive CAD representation methods are necessary for modelling all the design and manufacturing functions in an automated environment. Recent research work has concentrated on using Constructive Solid Geometry (CSG) methods and Boundary Representation (B-Rep) schemes for representing design and manufacturing functions. This paper presents several novel ideas on the application of octree and quadtree based representation schemes in several manufacturing areas such as robotic task planning, tolerance representation and inspection, feature-based design, and assembly modelling and verification. Suggestions on the application of extended octrees for modelling metal forming operations are also presented.     

Optimised CSG Tree Evaluation for Space Subdivision

Ray tracing is a well known technique for producing realistic computer images. The computational requirements of this method are such that optimisation techniques, for example space subdivision, must be used if complex scenes are to be rendered in reasonable times. Constructive solid geometry (CSG) is a method for describing the geometry of complex scenes by applying set operations to primitive objects. The status tree approach has been used successfully within ray tracing to evaluate CSG structures. This paper proposes a combination of the status tree and space subdivision techniques as a means to improve further the efficiency of ray tracing.     

基于图卷积网络的BREP→CSG转换方法及其应用研究

边界表示法(BREP)和构造实体表示法(CSG)是应用最广泛的2种实体表示法,在粒子输运计算辅助建模等领域对BREP→CSG自动转换算法有迫切的需求,但目前最常用的基于分割的BREP→CSG转换算法存在"计算量大、CSG表达过于复杂"等不足.观察到"拓扑相似的BREP模型的CSG表达结构类似",因此提出建立包含(BRE...     

On the kinematics of multiple manipulator space free-flyers and their computation

In this article, two basic approaches for kinematics modelling of multiple manipulator space free-flying robots (SFFRs) are developed. In the barycentric vector approach, the center of mass of the whole system is taken as a representative point for the translational motion of the system, and a set of body-fixed vectors which reflect both geometric configuration and mass distribution of the system are used. On the other hand, the direct path method relies on taking a point on the base body (preferably its center of mass) as the representative point for the translational motion of the system. The consequences of using each of the two approaches in deriving dynamics equations and in control design of SFFRs are discussed. It is revealed that the direct path method is a more appropriate approach for modelling multiple arm systems, in the presence of external forces/torques (i.e., free-flying mode). A 14 degree-of-freedom space free-flying system is considered as a benchmark system and a quantitative comparison between the two approaches is presented. The results show that the direct path method requires significantly less computations for position and velocity analyses. © 1998 John Wiley & Sons, Inc.     

空间代数曲线的参数化逼近

提出一种用三次B样条曲线逼近空间代数曲线的方法.对非奇异的情况,先用随机微分方程方法采样,然后对采样点进行聚类排序,最后用三次B样条曲线逼近有序点列;而对包含奇异点的情况,则将空间曲线双有理映射成平面曲线,采用已有的含奇异点的平面代数曲线的采样及排序方法来实现对应空间曲线的采样及排序.两种情况都获得了优于其它方法的逼近效果.     

明暗效果快速多变的CSG实本显示技术

CSG(Constructive Solid Geometry)是实体造型中一种重要表示方法.传统的CSG实 体显示方法不仅费时,而且难以控制明暗效果.本文提出的方法以一种新的CSG体素表面光 强生成模型为基础,结台深度缓冲技术,能快速有效地显示CSG实体,方便灵活地控制明暗效 果.