## Interactive Manipulation of Articulated Objects with Geometry Awareness (1999)

Venue: | In Proceedings of IEEE International Conference on Robotics and Automation |

Citations: | 3 - 1 self |

### BibTeX

@INPROCEEDINGS{Choi99interactivemanipulation,

author = {Min-hyung Choi and James F. Cremer},

title = {Interactive Manipulation of Articulated Objects with Geometry Awareness},

booktitle = {In Proceedings of IEEE International Conference on Robotics and Automation},

year = {1999},

pages = {592--598},

publisher = {}

}

### OpenURL

### Abstract

Techniques for interactive 3D manipulation of articulated objects in cluttered environments should be geometrically aware, going beyond basic inverse or forward kinematics to allow contact while preventing interpenetration. This paper describes a general purpose interactive object manipulation technique using nonlinear optimization. The method converts geometry awareness into sets of inequality constraints and handles nonlinear equality and inequality constraints efficiently without restricting object topology. Our iterative algorithm has a quadratic convergence rate and each iteration can be solved in O(n nz (L)), where n nz (L) is the number of non-zeros in L, a Cholesky factor of a sparse matrix. To promote additional speedup, symbolic factorization is separated from numerical computation. Our approach provides a framework for using optimization techniques in interactive tools for building and manipulating models in constrained, cluttered environments. 1 Introduction Many interact...

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Citation Context ...lue in computer graphics and virtual environments applications. In computer graphics, there have been a number of attempts to address the problem of manipulation of redundant articulated objects. Jack=-=[5]-=- uses a reduced coordinate system and nonlinear optimization techniques to solve inverse kinematics for a human model. Zhao[17] added collision avoidance to Jackbut this simple augmentation using boun... |

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Citation Context ... from a starting point at which allconstraints except the goals are satis ed. Assuming that inequality constraints have been replaced by equalities as described in Section 5.5, the Lagrangian function=-=[10] i-=-s de ned as L(q� )=E(q)+ X i i(q): (3) The rst order necessary condition for the existence of a local minimizer q of the objective function of Equation 1 requires the existence of a Lagrange multipl... |

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Citation Context ...n objects in close proximity. Gleicher's[11] di erential method casts the graphical manipulation problem to a nonlinear optimization problem, linearizing it to make the problem easier to solve. Snyder=-=[13]-=- addresses geometry awareness but not for articulated objects. The work investigated the generation of stable non-interpenetrating con gurations of curved-surface objects. Interactive dynamics simulat... |

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Citation Context ...nstraints. To ensure e ciency, it is important tokeep the set of active inequality constraints as small as possible. As mentioned in Section 4.2, details of our geometric analysis are presented in [9]=-=[8]-=-. The monitoring and management ofinequalities are important for the overall performance, because constraint addition or deletion can alter the block structure and necessitate further symbolic manipul... |

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Citation Context ...ally preferred [16] if the upper left corner block of the linear system 8 is a diagonal matrix. 5.2 The dense columns in JJ T To avoid dense decomposition we employ the modi ed Schur complement method=-=[4]-=-. The main idea is to rewrite the normal equation system 10 into 2 4 (AsA T s + FF T ) AD F A T D ;I 0 F T 0 I 32 54 3 5 = 2 4 b 0 0 3 5 (11) where As and AD are sparse and dense columns of J respecti... |

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Citation Context ...ut this simple augmentation using bounding spheres and cylinders does not support precise geometry awareness to allow contact or prevent interpenetration between objects in close proximity. Gleicher's=-=[11]-=- di erential method casts the graphical manipulation problem to a nonlinear optimization problem, linearizing it to make the problem easier to solve. Snyder[13] addresses geometry awareness but not fo... |