Boots – shoes – and leggings
Patent
1988-08-10
1991-06-18
Smith, Jerry
Boots, shoes, and leggings
36447429, 36447430, G05B 1941
Patent
active
050253620
DESCRIPTION:
BRIEF SUMMARY
FIELD OF INVENTION
This invention relates to a coordinate positioning system. More specifically, this invention relates to a method of and means for operating first and second coordinate positioning drives of a coordinate positioning apparatus to produce a resultant movement describing a curve.
The scope of this invention is specified in the claims hereto.
BRIEF DESCRIPTION OF THE DRAWINGS
An example of a system according to this invention will now be described with reference to the accompanying drawings wherein:
FIG. 1 is an elevation of a coordinate measuring machine;
FIG. 2 is an enlarged view along line II--II in FIG. 1 showing additionally a diagram of a path to be described by a member of the machine;
FIG. 3 is velocity/time diagram of the movement of said member along said path wherein said path is defined by two displacement vectors connecting three points;
FIG. 4a is a velocity/time diagram similar to FIG. 3 but wherein the displacement vectors are connected by a curve;
FIG. 4b is an acceleration/time diagram of FIG. 4a;
FIG. 5 (FIGS. 5a to 5e) is a flow diagram of a computer program and shows a main routine thereof;
FIG. 6 (FIGS. 6a to 6b) is a flow diagram of a first sub-routine of the program;
FIG. 7 (FIGS. 7a to 7b) is a flow diagram of a second sub-routine of the program; and
FIG. 8 is a flow diagram of a third sub-routine of the program.
DESCRIPTION OF PREFERRED EMBODIMENT
The machine (FIG. 1) has a probe 10 supported for three-dimensional motion in directions X,Y and Z. Measurement of the co-ordinate position of a surface of a workpiece 12 is determined automatically when the probe is moved into engagement with that surface. The motion of the probe is effected by motors MX,MY,MZ controlled by position-determining signals MX1,MY1,MZ1 generated by a computer 11 on the basis of position feedback signals MX2,MY2,MZ2 output by position-reading devices (not shown). For present purposes only the drive to the motors MX,MY is considered.
By way of example, the machine is required to measure the position of two surfaces 13,14 (FIG. 2) at opposite sides of a projection 15. Thus the probe, when moving from the surface 13 to the surface 14, has to circumnavigate the projection 15. To this purpose the computer has a program 99 (FIG. 1) to drive the probe along a path through points A,D,E,C wherein the path AD is part of a displacement vector SAB and the path EC is part of a displacement vector SBC. The vectors SAB, SBC are postulated to provide an initial orientation for the path, and a curve DE is introduced to shorten the path and to avoid the sharp change of direction which would occur if the movement were taken to the common point B of the two displacement vectors. Further, there is postulated for each path AB,BC a velocity vector VAB,VBC defined by a basic velocity profile VP1,VP2 (FIG. 3) comprising an initial acceleration period I,II, a period III of steady maximum velocity V1 or V2, and a final deceleration period IV,V. Such a basic profile is required to provide for the occasions when there is no need for a curve such as DE, e.g. if the probe 10 is required to reach the point B and stop there. However, inasmuch as there is need for the curve, the latter is arranged to connect the basic velocity profiles at the respective phases III of steady velocities thereof. Further, primarily for the reason that direction of the two paths AB,BC differ, there arises (as will be seen) a need for the curve itself to have a velocity profile and the program is written to provide for this.
The program is written to treat the displacement vectors SAB,SBC, the curve DE, and the velocity profiles VP1,VP2, entirely in terms of vector components in the co-ordinate directions.
Thus, bearing in mind that the example deals with the two-dimensional case, each displacement vector has components in the X and Y directions of its end points AX,AY,BX,BY, CX,CY (FIG. 2), and each velocity profile has X and Y velocity components V1X,V1Y,V2X,V2Y (FIG. 3). The motors MX,MY may be driven by velocity demand signals. However it
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Darlington Alan D.
Waggitt Kevin P.
Renishaw plc
Smith Jerry
Trammell Jim
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