偏差检查

Synopsis

DEVCHK/obj1[,obj1a],TO,obj2[,p1[,p2]][,TOLER,t1[,t2]]

Description

Allows you to perform four types of design check functions: curve to curve, curve to surface, edge to surface, and surface to surface. The system checks the continuity, tangency, and boundary alignment for specified surfaces and curves based on point/slope continuity. Point/slope continuity compares specified checkpoints on curves or surfaces. The results of the checking are output as a textual report to the current listing device. Temporarily displayed objects illustrate the points of deviation on the graphics screen.

The system performs one of the following checking methods based upon the objects you specify:

Curve To Curve checking verifies that one curve coincides with another curve. For example, this is useful to check approximately matching curves created using methods such as the following: (1) curve projection using different tolerances or (2) converting an existing curve to a B-spline.

Curve To Surface checking verifies that a curve located over a surface is actually on the surface. For example, you could check the quality of the match when a curve is supposed to lie completely on a surface, as in curve projection.

Edge To Surface checking compares the edge of a surface to the interior of another surface or to an adjacent surface. For example, you could check two adjacent surfaces to see if their common boundaries

Surface To Surface checking compares one entire surface with another surface for point/slope accuracy. For example, after trimming a surface, you could compare the new surface to the original for accuracy. After approximating a small section of a large, complex surface, you could compare the two to check the accuracy of approximation.

To perform deviation checking, specify the two objects you wish to check. You do not need to specify a checking method. The system performs the appropriate checking method based upon the objects specified. If you wish to perform edge to surface checking, you must specify an additional existing point (objla) that is closest to the endpoint of the edge to be checked.

The results of the deviation checking are sent to the current listing device. These results include an error summary, the coordinates of each point checked, the corresponding distance error, and the angle error.

The system temporarily displays objects on the graphics screen. All points checked by the system are represented by point symbols (+). Asterisks (*) are displayed at points where distance discontinuity occurs. Conehead vectors are displayed at points where angle errors occur.

In batch mode, since the interactive display of results is not possible, the system outputs the results of the deviation checking to a text file previously specified as the current listing device. The temporary display of checked points, points of distance discontinuity occurrences, and points of angle error occurrences cannot be output in batch mode.

Parameters

Parameter

Description

obj1

An existing curve or surface object that is checked with respect to another specified curve or surface.

obj1a

An existing point object. This point should be specified during edge to surface checking only, when both obj1 and obj2 are surfaces. The system checks the edge of obj1 for deviation against obj2 (a surface).

TO

Minor word indicating that obj1 is to be checked for deviation with respect to obj2.

obj2

An existing curve or surface object against which obj1 is checked for deviation.

p1

Optional input specifying the number of points along a curve or edge for deviation checking using the following methods: curve to curve, curve to surface, and edge to surface. For surface to surface checking, this field specifies the number of U gridpoints on surface 1 (obj1).

p2

Optional input for surface to surface deviation checking only. This field specifies the number of V gridpoints on surface 2 (obj2).

TOLER

Minor word indicating that the next optional fields specify tolerance values within which deviation checking is to be performed. If none is specified, the default is the value set in the Unigraphics option Preferences->Modeling. You can also read and set these tolerances using the GPAs &DISTOL and &ANGTOL.

t1

A positive numerical value or variable specifying the distance tolerance above which distance errors are reported, specified in inches or millimeters. The default is 0.01 inches.

t2

A positive numerical value or variable specifying the angle tolerance above which normal or tangent errors are reported, specified in radians. The default is 0.1 radians.

Parameter	Description
obj1	An existing curve or surface object that is checked with respect to another specified curve or surface.
obj1a	An existing point object. This point should be specified during edge to surface checking only, when both obj1 and obj2 are surfaces. The system checks the edge of obj1 for deviation against obj2 (a surface).
TO	Minor word indicating that obj1 is to be checked for deviation with respect to obj2.
obj2	An existing curve or surface object against which obj1 is checked for deviation.
p1	Optional input specifying the number of points along a curve or edge for deviation checking using the following methods: curve to curve, curve to surface, and edge to surface. For surface to surface checking, this field specifies the number of U gridpoints on surface 1 (obj1).
p2	Optional input for surface to surface deviation checking only. This field specifies the number of V gridpoints on surface 2 (obj2).
TOLER	Minor word indicating that the next optional fields specify tolerance values within which deviation checking is to be performed. If none is specified, the default is the value set in the Unigraphics option Preferences->Modeling. You can also read and set these tolerances using the GPAs &DISTOL and &ANGTOL.
t1	A positive numerical value or variable specifying the distance tolerance above which distance errors are reported, specified in inches or millimeters. The default is 0.01 inches.
t2	A positive numerical value or variable specifying the angle tolerance above which normal or tangent errors are reported, specified in radians. The default is 0.1 radians.