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US 10,967,469 B2Granted
System and method for fixture form-closure determination for part manufacturing with the aid of a digital computer
AssigneeSandvik Intellectual Property AB
InventorsSaigopal Nelaturi, Arvind Rangarajan, Tolga Kurtoglu, Christian Fritz
Life of this patent
Estimating the term…
Abstract
Automated fixture layout is approached in two distinct stages. First, the spatial locations of clamping points on the work piece are determined to ensure immobility of the fixtured part under any infinitesimal perturbation. Second, spatial locations are matched against a user-specified library of reconfigurable clamps to synthesize a valid fixture layout or configuration that includes clamps that are accessible and collision free. The spatial locations matching during the second stage can be the same spatial locations chosen in the first stage to ensure immobility, or a different set of spatial locations.
Claims20
A method for fixture form-closure determination for part manufacturing with the aid of a digital computer, comprising steps of:
- retrieving a part model and a constraint volume for a part to be manufactured, the part model and the constraint volume comprising geometric representations of the part respectively defining the boundary of the part and a region defined about the boundary of the part;
- identifying locations on the boundary of the part against which to contact a plurality of fixture elements that are affixed to a base plate;
- defining candidate fixturable locations within a wrench coordinate system and corresponding to the identified locations on the boundary of the part, each candidate fixturable location comprising both a position and a unit inward surface normal relative to an origin of the wrench coordinate system;
- assigning a point contact force along the unit inward surface normal from the position of each candidate fixturable location;
- mapping an applied force along each of the point contact forces to a wrench, each wrench comprising the applied force and a cross product of the applied force with the position of the point contact force;
- mapping each of the wrenches to a bin, each bin comprising a point space;
- sorting each of the wrenches by the bin to which the wrench is mapped and retaining the furthest points in the point space in each bin as extreme points;
- constructing a wrench matrix comprising vector columns corresponding to the extreme points retained in the bins of a plurality of the wrenches;
- combining a plurality of the extreme points from the bins exclusive of the wrench matrix as a potential configuration that comprises the candidate fixturable locations comprised in the positions of the point contact forces mapped to the wrenches comprised in the combination of the extreme points;
- testing containment of the origin within a convex hull implicitly-defined from the combination of the extreme points by solving for linear independence of the vector columns comprised in the wrench matrix, and establishing the form closure of the potential configuration upon implicit inclusion of the origin within the convex hull;
- and
- using the established form closure to synthesize a fixture layout for the part,
- wherein the steps are performed by a suitably-programmed computer.
10 more elements
A system for fixture form-closure determination for part manufacturing with the aid of a digital computer, comprising:
- a computer comprising a processor and memory within which code for execution by the processor is stored, the processor configured to:
- retrieve a part model and a constraint volume for a part to be manufactured, the part model and the constraint volume comprising geometric representations of the part respectively defining the boundary of the part and a region defined about the boundary of the part;
- identify locations on the boundary of the part against which to contact a plurality of fixture elements that are affixed to a base plate;
- define candidate fixturable locations within a wrench coordinate system and corresponding to the identified locations on the boundary of the part, each candidate fixturable location comprising both a position and a unit inward surface normal relative to an origin of the wrench coordinate system;
- assign a point contact force along the unit inward surface normal from the position of each candidate fixturable location;
- map an applied force along each of the point contact forces to a wrench, each wrench comprising the applied force and a cross product of the applied force with the position of the point contact force;
- map each of the wrenches to a bin, each bin comprising a point space;
- sort each of the wrenches by the bin to which the wrench is mapped and retaining the furthest points in the point space in each bin as extreme points;
- construct a wrench matrix comprising vector columns corresponding to the extreme points retained in the bins of a plurality of the wrenches;
- combine a plurality of the extreme points from the bins exclusive of the wrench matrix as a potential configuration that comprises the candidate fixturable locations comprised in the positions of the point contact forces mapped to the wrenches comprised in the combination of the extreme points;
- test containment of the origin within a convex hull implicitly-defined from the combination of the extreme points by solving for linear independence of the vector columns comprised in the wrench matrix, and establishing the form closure of the potential configuration upon implicit inclusion of the origin within the convex hull;
- and
- use the established form closure to synthesize a fixture layout for the part.
10 more elements
Dependencies are inferred from the claim text.