A complete algorithm for synthesizing modular fixtures for polygonal parts
- Sandia National Labs., Albuquerque, NM (United States)
- University of Southern California, Los Angeles, CA (United States)
Commercially-available nuclear fixturing systems typically include a square lattice of tapped and bushed holes with precision locating and clamping elements that can be rigidly attached to the lattice using dowel pins or expanding mandrels. Currently, human expertise is required to synthesize a suitable arrangements of these elements to hold a given part. Besides being time consuming, if the set of alternatives is not systematically explored, the designer may fail to find an acceptable fixture or may settle upon a suboptimal fixture. We consider a class of modular fixtures that prevent a part from translating or rotting in the plane using four point contacts on the part`s boundary. These fixtures are based on three round locators, each centered on a lattice point, and one translating clamp. We present an algorithm that accepts a polygonal part shape as input and synthesizes the set of all fixture designs that achieve form closure for the given part. The algorithm also allows the user to specify geometric access constraints on fixtures. If the part has n edges and its maximal diameter is d lattice units, the asymptotic running time of the algorithm is O(n{sup 5}d{sup 5}). We have implemented the algorithm and present example fixtures that it has synthesized. This implementation includes a metric to rank fixtures based on their ability to resist applied forces. We believe this is the first fixture synthesize algorithm that is complete in the sense that it is guaranteed to find an admissible fixture if one exists. Furthermore, the algorithm is guaranteed to find the optimal fixture, relative to any well-defined quality metric.
- Research Organization:
- Sandia National Labs., Albuquerque, NM (United States)
- Sponsoring Organization:
- USDOE, Washington, DC (United States); National Science Foundation, Washington, DC (United States)
- DOE Contract Number:
- AC04-94AL85000
- OSTI ID:
- 10105197
- Report Number(s):
- SAND--93-2028C; CONF-940550--9; ON: DE94002932; BR: GB0103012; CNN: Grant IRI-9123747; Grant DDM-9215362
- Country of Publication:
- United States
- Language:
- English
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