Process for acquiring data representative of the shape of an object

A process for acquiring data representative of the shape of an object comprising the steps of:

• choosing an object having a surface the shape of which may be represented by a plurality of points defining poles;
• moving one end of a feeler and said object into contact with one another at a succession of contact points defining said poles such that said contact points lie in a plane within a reference coordinate system;
• detecting said contact between said object and feeler to define said poles;
• determining in said reference coordinate system the coordinates of said poles in said plane;
• storing the coordinates of said poles;
• computing from said poles a plurality of arcs of circles defining the shape of the object between said poles, each arc being defined by at least two of said poles and wherein the arc between two non-consecutive poles is defined by a portion of a circle passing through said two non-consecutive poles and another pole situated therebetween, said computing step including,
• selecting three non-consecutive poles including a starting pole,
• calculating the arc of a circle passing through said three non-consecutive poles,
• determining if the distance between the arc passing through said three non-consecutive poles and each of any intermediate poles is less than a predetermined value,
• repeating said selecting and calculating steps when said distance is less than said predetermined value for a different three non-consecutive poles separated by a greater distance and including said starting pole, and
• deleting the storage of said intermediate poles between said starting pole and the third of said three non-consecutive poles and storing said computed arc between said starting and third pole upon a detection of a distance between said computed arc and at least one intermediate pole exceeding said predetermined value;
• and
• providing a set of coordinates of said poles and of computed arcs as data representing the shape of said object.

The process for acquiring data representative of the shape of an object comprising the steps of:

• choosing an object having a surface the shape of which may be represented by a plurality of points defining poles;
• moving one end of a feeler and said object into contact with one another at a succession of contact points defining said poles such that said contact points lie in a plane within a reference coordinate system, said feeler including a rounded end;
• detecting said contact between said object and feeler to define said poles;
• determining in said reference coordinate system the coordinates of said poles in said plane;
• storing the said coordinates of said poles;
• computing from said poles a plurality of arcs of circles defining the shape of the object between said poles, each arc being defined by at least two of said poles;
• providing a set of coordinates of said poles and of computed arcs as data representing the shape of said object;
• and
• moving said feeler and object relative to one another for detecting poles in a plurality of planes each defining a separate contour of said object to determine the poles of at least three successive adjacent planes defining three contours of said object, and further comprising,
• selecting three poles from said three planes which lie in a plane normal to the planes defining said contours,
• determining the value of a ridge defined between the first and second contours in said normal plane,
• extrapolating the coordinate of a point of a projected contour beyond said third contour,
• repeating said selecting, determining and extrapolation for the three poles of three planes in a different plane normal to said three adjacent contours, and
• moving said feeler a distance equal to the smallest variation between a pole of said third contour and the projected pole for determining the next successive series of poles defining a plane.

A process for acquiring data representative of the shape of an object comprising the steps of:

• choosing an object having a surface the shape of which may be represented by a plurality of points defining poles;
• moving one end of a feeler and said object into contact with one another at a succession of contact points defining said poles such that said contact points lie in a plane within a reference coordinate system, said feeler including a rounded end;
• detecting said contact between said object and feeler to define said poles;
• determining in said reference coordinate system the coordinates of said poles in said plane;
• storing the said coordinates of said poles;
• computing from said poles a plurality of arcs of circles defining the shape of the object between said poles, each arc being defined by at least two of said poles;
• providing a set of coordinates of said poles and of computed arcs as data representing the shape of said object;
• moving said feeler and object relative to one another for detecting poles in a plurality of planes each defining a separate contour of said object to determine the poles of at least three successive adjacent planes defining three contours of said object, and further comprising,
• selecting three poles from said three planes which lie in a plane normal to the planes defining said contours,
• determining the value of a ridge defined between the first and second contours in said normal plane,
• repeating the selecting and determining steps for a plurality of normal planes,
• selecting the normal plane having the greatest ridge value between the first and second contours,
• extrapolating the coordinates of a point for a projected contour beyond the pole of the second contour of the normal plane having the greatest ridge value between the first and second contours, and
• moving said feeler in a direction to select a new contour by a value corresponding to the difference between the selected pole of said third contour in said normal plane and said extrapolated point of the corresponding projected contour.