Automatic design of 3-d fixtures and assembly pallets

Brost, Randy C.; Peters, R.R.

doi:10.2172/446349

Cited by 7 publications

(5 citation statements)

References 30 publications

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“…Our work is related to other industrial automation problems, such as the design of work-holding fixtures (Wallack and Canny 1994;Brost and Goldberg 1996;Wallack and Canny 1996;Sudsang et al 1997;Brost and Peters 1998) and parts orienting (Grossman and Blasgen 1975;Erdmann and Mason 1988;Goldberg 1993;Canny and Goldberg 1994b;Kriegman 1997), where the ideas of using knowledge of stable poses and iterative randomized blind manipulation strategies are well known, and have even been used in the context of simple hands (Mason and Salisbury 1985;Goldberg 1993). Broad arguments in favor of simplicity in industrial automation algorithms and hardware are advanced under the name 'RISC Robotics' (Canny and Goldberg 1994a,b).…”

Section: Simple Handsmentioning

confidence: 99%

Autonomous manipulation with a general-purpose simple hand

Mason

Rodríguez

Srinivasa

et al. 2011

The International Journal of Robotics Research

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While complex hands seem to offer generality, simple hands are often more practical. This raises the question: how do generality and simplicity trade off in the design of robot hands? This paper explores the tension between simplicity in hand design and generality in hand function. It raises arguments both for and against simple hands, it considers several familiar examples, and it proposes an approach for autonomous manipulation using a general-purpose but simple hand. We explore the approach in the context of a bin-picking task, focused on grasping, recognition, and localization. The central idea is to use learned knowledge of stable grasp poses as a cue for object recognition and localization. This leads to some novel design criteria, such as minimizing the number of stable grasp poses. Finally, we describe experiments with two prototype hands to perform bin-picking of highlighter markers.

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Section: Simple Handsmentioning

confidence: 99%

Autonomous manipulation with a general-purpose simple hand

Mason

Rodríguez

Srinivasa

et al. 2011

The International Journal of Robotics Research

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“…A key part of tolerance modeling is representing the tolerance zone in an appropriate way so that variations of tolerances can be obtained and propagated. Worst case estimation models the uncertainties of tolerances by simple geometric entities that are guaranteed to bound variations of dimensions [1,6]. Geometric objects employed are usually higher dimensional polytopes or dual-cones, which represent the allowed region as intervals of coefficients in their algebraic parameterization [27,23,10].…”

Section: Prior Workmentioning

confidence: 99%

Statistical geometric computation on tolerances for dimensioning

Keyser

2016

Computer-Aided Design

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“…The notion of a stable equilibrium is closely related to force closure and form closure in robotic grasping [21], [26] and fixture design for a static assembly [9], [10]. Trinkle [33] formulated a first-order stability criterion for grasped objects based on linear programming.…”

Section: A Stability Analysismentioning

confidence: 99%

The Influence of Motion Paths and Assembly Sequences on the Stability of Assemblies

Rakshit

Akella

2015

IEEE Trans. Automat. Sci. Eng.

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In this paper, we present an approach for the stability analysis of mechanical part disassembly considering part motion in the presence of physical forces such as gravity and friction. Our approach uses linear complementarity to analyze stability as parts are moved out of the assembly. As each part is removed from the assembly along a specified path during disassembly, we compute the contact forces between parts in the remaining assembly; positive contact forces throughout the disassembly process imply the disassembly sequence is stable (since the parts remain in contact with one another). However, if the part that is being taken out induces motion of other parts in the remaining subassembly, we conclude the disassembly sequence is unstable. Thus, we are able to simulate the entire disassembly considering physical forces and part motion, which has not previously been done. We then show the influence of part motion on stable disassembly. In contrast to prior work on disassembly that has focused either on planning part motions based on only geometric constraints, or on analyzing the stability of an assembly without considering part motions, we explore the relation between part motion and the selection of stable disassembly sequences in 2-D and 3-D. We establish conditions that characterize path-dependent assemblies, where motion paths can play a significant role in stable disassembly. Since we track the motion of all parts in an assembly, instability inducing motions can be identified and prevented by introducing appropriate fixtures by selecting alternative disassembly sequences or by changing the motion paths. We extend the stability analysis for single part disassembly to stability analysis of subassembly disassembly. We additionally show that in the presence of friction, assembly and disassembly can be noninvertible.Note to Practitioners-Maintaining the stability of an assembly as assembly or disassembly proceeds is critical during product assembly, repair, and maintenance. While fixtures can ensure stability, they add cost and restrict access for parts and tools. We show that the stability of the assembly can depend on the paths taken by the parts, and present an approach for selecting paths that ensure stability from among the geometrically feasible paths. The main application is in assembly and disassembly planning for reducing the fixturing requirements and in planning assembly motions that do not cause instability. The results will also be useful in designing disassembly operations during maintenance or repair, when it may not be possible to fixture all parts. The stability analysis can also be used by assistive robots in domestic environments for tasks like Manuscript stacking objects and for safe removal of collapsed structures after disasters such as earthquakes.

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Automatic design of 3-d fixtures and assembly pallets

Cited by 7 publications

References 30 publications

Autonomous manipulation with a general-purpose simple hand

Autonomous manipulation with a general-purpose simple hand

Statistical geometric computation on tolerances for dimensioning

The Influence of Motion Paths and Assembly Sequences on the Stability of Assemblies

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