Yan Zhuang, Ken Goldberg, and Yin-Chung Wong. On the existence of modular fixtures. In International Conference on Robotics and Automation. IEEE, May 1994. 14  Home/Search   Document Details and Download   Summary   Related Articles   Check

....and fixturing in particular. Mishra has studied the problem of designing fixtures for rectilinear parts using toe clamps attached to a regular grid, and proven the existence of fixtures using six clamps [34] this result has since then been tightened to four clamps by Zhuang, Goldberg, and Wong [59]) In keeping with the idea of Reduced Intricacy Sensing and Control (RISC) robotics of Canny and Goldberg [6] Wallack and Canny [57, 58] and Brost and Goldberg [5] have recently proposed very simple modular fixturing devices and efficient algorithms for constructing form closure fixtures of ....

....design is shown in Figure 3. There are obviously polyhedral objects which cannot be fixtured with our device (a trivial example is an object whose diameter is smaller than the inter locator distance) It would be interesting to characterize precisely the class of fixturable objects (see [59] for a discussion of the two dimensional case) Another interesting avenue of research would be to extend the proposed algorithm to parts bounded by algebraic patches (see [58, Chapter 6] for the twodimensional case) Our overall approach extends to this case in a straightforward way, but working ....

Y. Zhuang, K. Goldberg, and Y.C. Wong. On the existence of modular fixtures. In IEEE Int. Conf. on Robotics and Automation, pages 543--549, San Diego, CA, May 1994.

.... stability of immobilizing grasps) There are obviously polyhedral objects which cannot be fixtured with our device (a trivial example is an object whose diameter is smaller than the inter locator distance) It would be interesting to characterize precisely the class of fixturable objects (see [28] for a discussion of the 2D case) Another interesting avenue of research would be to extend the proposed algorithm to parts bounded by algebraic patches (see [26, Chapter 6] for the 2D case) Our overall approach extends to this case in a straightforward way, but working out the details of how to ....

Y. Zhuang, K. Goldberg, and Y.C. Wong. On the existence of modular fixtures. In IEEE Int. Conf. Robot. Autom., pp. 543--549, San Diego, CA, May 1994.

....and fixturing in particular. Mishra has studied the problem of designing fixtures for rectilinear parts using toe clamps attached to a regular grid, and proven the existence of fixtures using six clamps [29] this result has since then been tightened to four clamps by Zhuang, Goldberg, and Wong [55]) In keeping with the idea of Reduced Intricacy Sensing and Control (RISC) robotics of Canny and Goldberg [6] Wallack and Canny [53, 54] and Brost and Goldberg [4] have recently proposed very simple modular fixturing devices and efficient algorithms for constructing form closure fixtures of ....

Y. Zhuang, K. Goldberg, and Y.C. Wong. On the existence of modular fixtures. In IEEE Int. Conf. on Robotics and Automation, pages 543--549, San Diego, CA, May 1994. 41

....These fingers should be molded to the object s contours so as to either minimize or totally prevent any extraneous motions. This area of research appears to be largely, if not entirely, unexplored; however, some similar work has been done by Wallack and Canny [11] Zhuang, Goldberg and Wong [12], Brost and Goldberg [13] Canny and Goldberg [14] and Asada and By [15] in the field of modular fixtures. We expect that this previous body of research will provide valuable input in the development of gripper design algorithms. 2 CAD based finger fabrication via rapid prototyping technology ....

....alternate solutions. This can be done by rotating and or translating one or more of the parts in question, and then repeating the algorithm. In order to efficiently explore these possibilities, attempts to devise a formal methodology can draw on previous research into the use on modular fixtures [11, 12, 13, 14, 15]. This body of work has typically explored the idea of computing a set of contact points that would hold a part securely within a fixture. It may be possible to extend these attempts to more than one object though, by generating combinations of contact point sets and evaluating their feasibility. ....

Y. Zhuang, K. Goldberg and Y-C. Wong. "On the existence of modular fixtures," Proceedings of the IEEE International Conference on Robotics and Automation, pp. 543--549, 1994.

....another part into it. Most fixturing devices today are designed for specific parts and thus are not reusable. The research in flexible fixturing tries to automatically generate fixturing points for parts and to design modular fixtures that are reusable and can be easily assembled by a robot [BG94, ZGW94] ffl Grasp planning: Research in grasp planning addresses the problem of finding stable grasps of a part with given geometry. The set of stable grasps then further constrain possible assembly sequences that can be performed by a robot. It also addresses the problem of how to choose a stable ....

Y. Zhuang, K. Goldberg, and Y.-C. Wong. On the existence of modular fixtures. In 1994 IEEE internation Conference on Robotics and Automation, pages 543--551, San Diego, CA, May 1994.

....open questions in the area that remain unsolved. 1. Introduction In robotics and manufacturing, the problem of grasping, fixturing and workholding occupies a central position. While the question of analyzing and synthesizing a closure grasp or a fixture is fairly well studied (see for instance [1, 5, 6, 7, 9, 10, 12, 16]) the question of formalizing a satisfactory notion of a grasp metric, and devising efficient algorithm for synthesizing grasps of good quality has received relatively less attention. A systematic exploration in this direction was initiated in the work of Kirkpatrick, Mishra and Yap [3] where a ....

.... (6) Another problem of interest is to study the similar optimality problem in the case of fixturing, where a polygonal object has to be fixtured by a set of toe clamps that can be placed only at places designated by a set of toe slots (which are usually arranged on a regular square grid) [1, 6, 7, 16]. The added difficulty arises because of the geometric constraints imposed by the toe slots. It is easily seen that for a rectilinear object the optimal fixel (fixture element) placement can be determined in O(n) time. However, the problem seems quite difficult even when we consider a convex ....

Y. Zhuang, K.Y. Goldberg and Y-C. Wong. "On the Existence of Modular Fixtures," Submitted to the 1994 IEEE International Conference on Robotics and Automation , 1994. Appears in Proceedings of the 1994 International Workshop on Intelligent Robots and Systems: IRS'94, Grenoble, (France), July 11--14, 1994.

....response to a time varying external wrench [18] ffl Study of the strength (also called, efficiency) of a grasp [9, 14] The algorithms and the bounds are based on a quantitative version of the Steinitz s theorem. Also, see [2] ffl Analysis and planning algorithms for fixturing and workholding [3, 19, 20, 35]. Several other approaches to these problems have emerged, contemporaneously or subsequently. Notable among these approaches are purely geometric techniques [4, 10, 16, 25, 31] topological techniques [12] and algebraic techniques [28, 29] However, while in certain instances these other ....

....metrics. 6) Another problem of interest is to study the similar optimality problem in the case of fixturing, where a polygonal object has to be fixtured by a set of toeclamps that can be placed only at places designated by a set of toe slots (which are usually arranged on a regular square grid) [3, 35, 19, 20]. The added difficulty arises because of the geometric constraints imposed by the toe slots. It is easily seen that for a rectilinear object the optimal fixel (fixture element) placement can be determined in O(n) time. However, the problem B. Mishra seems quite difficult even when we consider a ....

[Article contains additional citation context not shown here]

Y. Zhuang, K.Y. Goldberg and Y-C. Wong. "On the Existence of Modular Fixtures," Submitted to the 1994 IEEE International Conference on Robotics and Automation, 1994.

....for prismatic polyhedral objects using a modular fixturing system consisting of fixture elements and a translating clamp, all mounted on a fixture plate. Zhuang et al. proved that their fixturing system is incomplete by presenting a class of arbitrarily sized polygons which cannot be fixtured [16]. There have yet to be found any polygons or classes of polygons which cannot be fixtured using an appropriately sized fixture vise toolkit. Furthermore, all of translating clamp fixtures produced by Brost and Goldberg s algorithm correspond to fixture vise configurations where one of the fixture ....

Yan Zhuang, Ken Goldberg, and Yin Chung Wong. On the existence of modular fixtures. In IEEE International Conference on Robotics and Automation, pages 543--549, San Diego, California, 1994.

....and fixturing in particular. Mishra has studied the problem of designing fixtures for rectilinear parts using toe clamps attached to a regular grid, and proven the existence of fixtures using six clamps [34] this result has since then been tightened to four clamps by Zhuang, Goldberg, and Wong [59]) In keeping with the idea of Reduced Intricacy Sensing and Control (RISC) robotics of Canny and Goldberg [6] Wallack and Canny [57, 58] and Brost and Goldberg [5] have recently proposed very simple modular fixturing devices and efficient algorithms for constructing form closure fixtures of ....

....conceptual design is shown in Figure 3. There are obviously polyhedral objects which cannot be fixtured with our device (a trivial example is an object whose diameter is smaller than the inter locator distance) It would be interesting to characterize precisely the class of fixturable objects (see [59] for a discussion of the two dimensional case) Another interesting avenue of research would be to extend the proposed algorithm to parts bounded by algebraic patches (see [58, Chapter 6] for the twodimensional case) Our overall approach extends to this case in a straightforward way, but working ....

Y. Zhuang, K. Goldberg, and Y.C. Wong. On the existence of modular fixtures. In IEEE Int. Conf. on Robotics and Automation, pages 543--549, San Diego, CA, May 1994.

....and fixturing in particular. Mishra has studied the problem of designing fixtures for rectilinear parts using toe clamps attached to a regular grid, and proven the existence of fixtures using six clamps [17] this result has since then been tightened to four clamps by Zhuang, Goldberg, and Wong [36]) In keeping with the idea of Reduced Intricacy Sensing and Control (RISC) robotics of Canny and Goldberg [4] Wallack and Canny [34, 35] Brost and Goldberg [2] have recently proposed very simple modular fixturing devices and efficient algorithms for constructing form closure fixtures of ....

Y. Zhuang, K. Goldberg, and Y.C. Wong. On the existence of modular fixtures. In IEEE Int. Conf. on Robotics and Automation, pages 543--549, San Diego, CA, May 1994.

.... problems such as sensorless orienting of parts (Goldberg [76] and controllability and motion planning for nonholonomic mobile robots in the obstacle free plane (Barraquand and Latombe [14] He describes a modular fixturing problem for polygonal parts (Zhuang, Wong, and Goldberg [189]) that is not solution complete, but for which a complete algorithm, an algorithm guaranteed to return a solution if it exists and report failure otherwise, 18 CHAPTER 1. INTRODUCTION exists (Brost and Goldberg [34] Characterizing problems in this manner and developing complete algorithms to ....

Y. Zhuang, Y.-C. Wong, and K. Y. Goldberg. On the existence of modular fixtures. In IEEE International Conference on Robotics and Automation, pages 543--549, San Diego, CA, May 1994.

.... stability of immobilizing grasps) There are obviously polyhedral objects which cannot be fixtured with our device (a trivial example is an object whose diameter is smaller than the inter locator distance) It would be interesting to characterize precisely the class of fixturable objects (see [28] for a discussion of the 2D case) Another interesting avenue of research would be to extend the proposed algorithm to parts bounded by algebraic patches (see [26, Chapter 6] for the 2D case) Our overall approach extends to this case in a straightforward way, but working out the details of how to ....

Y. Zhuang, K. Goldberg, and Y.C. Wong. On the existence of modular fixtures. In IEEE Int. Conf. Robot. Autom., pp. 543--549, San Diego, CA, May 1994.

....in manufacturing where many assembly tasks require a set of contacting objects to be held firmly. Fixture elements or fixels are positioned in contact with the objects to achieve this. Often there is only a finite set of possible placements due to the construction of the workholding table [Mis91, ZGW94] see Figure 2) In this setting, forces applied to an object are due both to contacts between objects, and between objects and fixtures (see Figure 3) As in grasping, it is desirable to use a small number of fixtures, and or limit the forces they must apply on the objects. The previous ....

Y. Zhuang, K.Y. Goldberg, and Y.-C. Wong. On the existence of modular fixtures. In IEEE International Conference on Robotics and Automation, pages 543--549, San Diego, CA, 1994.

....arises in manufacturing where many assembly tasks require a set of contacting objects to be held firmly. Fixture elements or fixtures are positioned in contact with the objects to achieve this. Often there is only a finite set of possible placements due to the construction of the workholding table [ZGW94]. In this setting, forces applied to an object are due both to contacts between objects, and between objects and fixtures. As in grasping, it is desirable to use a small number of fixtures, and or limit the forces they must apply on the objects. The previous framework generalizes to this case by ....

Y. Zhuang, K.Y. Goldberg, and Y.-C. Wong. On the existence of modular fixtures. In IEEE International Conference on Robotics and Automation, pages 543--549, San Diego, CA, 1994.

....In modular fixturing, contact locations are restricted by the lattice of holes, and form closure cannot always be achieved. In particular, when three locators and one clamp are used on a workholding plane, there exist polygons of arbitrary size for which no fixture design can be achieved [ZGW94] but, if parts are restricted to be rectilinear, a fixture can always be found as long as all edges have length of four or more lattice units [Mis91] When the fixturing kit consists of a latticed workholding plane, three locators, and one clamp, the algorithm in [BG96] finds all possible ....

Y. Zhuang, K.Y. Goldberg, and Y. Wong. On the existence of modular fixtures. In Proc. IEEE Int. Conf. on Rob. and Autom., pages 543--549, 1994.

....manufacturing where many assembly tasks require a set of contacting objects to be held firmly. Fixture elements or fixels are positioned in contact with the objects to achieve this. Often there is only a finite set of possible placements due to the construction of the workholding table [Mis91, ZGW94] In this setting, forces applied to an object are due both to contacts between objects, and between objects and fixtures. As in grasping, it is desirable to use a small number of fixtures, and or limit the forces they must apply on the objects. The previous framework generalizes to this case by ....

Y. Zhuang, K.Y. Goldberg, and Y.-C. Wong. On the existence of modular fixtures. In IEEE International Conference on Robotics and Automation, pages 543--549, San Diego, CA, 1994.

....Mishra [Mishra, Schwartz, and Sharir 1987] applied work on grasping to the problem of designing modular fixtures using a regular lattice. Mishra gave the first existence results [Mishra 1991] as described in Section 5.1 below. This paper is a substantially revised and extended version of [Zhuang, Goldberg, and Wong 1994]. 3 Preliminaries We define a regular lattice as a 2D plane on which the lattice sites are arranged in rows and columns with uniform unit distance. Henceforth, all distances are given in units of lattice spacing. We assume that the lattice is larger than the part to be fixtured. Since contacts ....

Yan Zhuang, Ken Goldberg, and Yin-Chung Wong. On the existence of modular fixtures. In International Conference on Robotics and Automation. IEEE, May 1994. 14

....we plan to purchase memory for Prof. Ram Nevatia s IRIS Indigo, which he has graciously agreed to let us use as a platform for Silma s CIMstation as part of the collaboration with Adept. Next month, at the IEEE International Conference on Robotics and Automation, our group will present 4 papers [2, 3, 4, 5] . Based on a suggestion by Howard Moraff, I also organized a workshop on Design of Parts and Devices for Automation which will be held in conjunction with the Conference (see enclosed) During the third year of the Award, we expect to make progress toward the goal of of developing a practical ....

Yan Zhuang, Yin-Chung Wong, and Ken Goldberg. On the existence of modular fixtures. In International Conference on Robotics and Automation. IEEE, May 1994. Also available as USC Techreport IRIS-93-314.

....contacts. Mishra [Mishra, Schwartz, and Sharir 1987] applied work on grasping to the problem of designing modular fixtures using a regular lattice. Mishra gave the first existence results [Mishra 1991] as described in Section 5.1 below. This paper is a substantially revised and extended version of [Zhuang, Goldberg, and Wong 1994]. 3 Preliminaries We define a regular lattice as a 2D plane on which the lattice sites are arranged in rows and columns with uniform unit distance. Henceforth, all distances are given in units of lattice spacing. We assume that the lattice is larger than the part to be fixtured. Since contacts ....

Yan Zhuang, Ken Goldberg, and Yin-Chung Wong. On the existence of modular fixtures. In International Conference on Robotics and Automation. IEEE, May 1994.

....to the lattice spacing it may fall between the holes and thus not be fixturable. However, we might conjecture that for parts of sufficient width the method is complete: it is always possible to find a 3L 1C fixture to hold the part. Below we construct a counterexample; details can be found in [31]. The maximum and minimum values of the width function are well defined; we denote them with d(S) and d(S) respectively. The minimum width of a part is a useful way to characterize its size. To construct a polygonal part of arbitrary size that is unfixturable, we show that for any given ....

Yan Zhuang, Yin-Chung Wong, and Ken Goldberg. On the existence of modular fixtures. In International Conference on Robotics and Automation. IEEE, May 1994. Also available as USC Techreport IRIS-93-314.

....form closure of a given polygonal part. The give a complete algorithm that efficiently enumerates form closure placements of locators and clamp and ranks these fixtures by a variety of quality metrics. The completeness [39] of different fixture models for restricted classes of parts is explored in [40, 41]. 7 RISC and Design The RISC approach to manufacturing replaces general purpose sensors and actuators with special purpose, modular hardware. A dextrous arm manipulator camera combination can be thought of as an interpreter for assembly plans. The assembly sequence can be changed with minimal ....

Yan Zhuang, Yin-Chung Wong, and Ken Goldberg. On the existence of modular fixtures. In International Conference on Robotics and Automation. IEEE, May 1994. Also available as USC Techreport IRIS-93-314.

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Y. Zhuang, K. Y. Goldberg and Y. C. Wong "On the Existence Of Modular Fixtures", IEEE International Conference on Robotics and Automation, San Diego, CA, pp. 543-549 May

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