Control point

Abstract: This paper presents an innovative method for inserting test points in the circuit-under-test to obtain complete fault coverage for a specified set of test patterns. Rather than using probabilistic techniques for test point placement, a path tracing procedure is used to place both control and observation points. Rather than adding extra scan elements to drive the control points, a few of the existing primary inputs to the circuit are ANDed together to form signals that drive the control points. By selecting which patterns the control point is activated for, the effectiveness of each control point is maximized. A comparison is made with the best previously published results for other test point insertion methods, and it is shown that the proposed method requires fewer test points and less overhead to achieve the same or better fault coverage.

Abstract: In Chapters 7 and 8 we showed how to construct NURBS representations of common and relatively simple curves and surfaces such as circles, conics, cylinders, surfaces of revolution, etc. These entities can be specified with only a few data items, e.g., center point, height, radius, axis of revolution, etc. Moreover, the few data items uniquely specify the geometric entity. In this chapter we enter the realm of free-form (or sculptured) curves and surfaces. We study fitting, i.e., the construction of NURBS curves and surfaces which fit a rather arbitrary set of geometric data, such as points and derivative vectors. We distinguish two types of fitting, interpolation and approximation. In interpolation we construct a curve or surface which satisfies the given data precisely, e.g., the curve passes through the given points and assumes the given derivatives at the prescribed points. Figure 9.1 shows a curve interpolating five points and the first derivative vectors at the endpoints. In approximation, we construct curves and surfaces which do not necessarily satisfy the given data precisely, but only approximately. In some applications — such as generation of point data by use of coordinate measuring devices or digitizing tablets, or the computation of surface/surface intersection points by marching methods — a large number of points can be generated, and they can contain measurement or computational noise. In this case it is important for the curve or surface to capture the “shape” of the data, but not to “wiggle” its way through every point. In approximation it is often desirable to specify a maximum bound on the deviation of the curve or surface from the given data, and to specify certain constraints, i.e., data which is to be satisfied precisely. Figure 9.2 shows a curve approximating a set of m + 1 points. A maximum deviation bound, E, was specified, and the perpendicular distance, e i , is the approximation error obtained by projecting Q i on to the curve. The e i , of each point, Q i , is less than E. The endpoints Q0 and Q m were specified as constraints, with the result that e0 = e m = 0.

Abstract: A system and method for tracking a global shape of an object in motion is disclosed. One or more control points along an initial contour of the global shape are defined. Each of the one or more control points is tracked as the object is in motion. Uncertainty of a location of a control point in motion is represented using a number of techniques. The uncertainty to constrain the global shape is exploited using a prior shape model. In an alternative embodiment, multiple appearance models are built for each control point and the motion vectors produced by each model are combined in order to track the shape of the object. The movement of the shape of the object can be visually tracked using a display and color vectors.