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Claims  |
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What is claimed is:
1. Method for cooperatively controlling motion of a tool centerpoint
associated with the function element carried by a manipulator and rotation
of a workpiece carried by a positioner, the motion effected by the
manipulator being along a linear path intersecting the axis of rotation of
the workpiece, the motion being defined by input signals, the manipulator
and positioner having movable members driven by actuators controlled by
servomechanism circuits, the relative motion of the tool centerpoint and
workpiece surface being effected at a velocity represented by an input
signal, the method comprising the steps of:
a. iteratively producing incremental velocity signals in response to the
input signals, each incremental velocity signal representing the velocity
of the tool centerpoint during an iteration interval;
b. modifying the incremental velocity signals in proportion to the change
in radial distance of the tool centerpoint from the axis of rotation of
the workpiece between successive iterations;
c. producing intermediate location coordinate signals in response to the
modified incremental velocity signals, the intermediate location
coordinate signals representing coordinates relative to a rectangular
coordinate system associated with the manipulator of an intermediate
location along the linear path of the tool centerpoint and an intermediate
rotation of the workpiece; and
d. applying the intermediate location coordinate signals to the
servomechanism circuits to effect coordinated motion of the movable
members of the manipulator and positioner.
2. The method of claim 1 wherein the input signals define coordinates of
starting and ending locations of the tool centerpoint motion and the
workpiece rotation and the relative velocity between the tool centerpoint
and the workpiece surface and the method further comprises the steps of:
a. producing an effective linear distance signal representing the distance
resulting from the combination of tool centerpoint motion and workpiece
rotation; and
b. producing an adjusted programmed velocity signal in response to the
effective linear distance signal, the adjusted programmed velocity signal
representing the velocity of the tool centerpoint which results in a
relative velocity between the tool centerpoint and the workpiece surface
equal to the programmed velocity.
3. The method of claim 2 wherein the step of producing intermediate
location coordinate signals further comprises the steps of:
a. producing a programmed distance signal representing the larger of the
linear distance traversed by the tool centerpoint between two programmed
locations and the arc length swept by the average radial distance of the
tool centerpoint from the axis of rotation when rotated through the
programmed angular change of the workpiece;
b. producing coordinate component ratio signals, each coordinate component
ratio signal representing the quotient of the change in magnitude of a
selected coordinate and the programmed distance signal;
c. producing an incremental distance signal in response to the increment
velocity signal and an interation interval signal representing the period
between iterations, the incremental distance signal representing an
increment of motion occurring over the iteration period; and
d. producing coordinate component signals in response to the incremental
distance signal and the coordinate component ratio signals, the coordinate
component signals representing coordinate components of the incremental
distance.
4. The method of claim 3 wherein the axis of rotation of the workpiece is
not parallel to any of the axes of the manipulator rectangular coordinate
system and the step of modifying the incremental velocity signals further
comprises the steps of:
a. producing transformed coordinate signals representing coordinates of
programmed locations relative to a workpiece positioner coordinate system;
b. producing intermediate radial distance signals in response to the
transformed coordinate signals, the intermediate radial distance signals
representing the radial distance from the axis of rotation of the
workpiece to the intermediate tool centerpoint location; and
c. producing a modified increment velocity signal in response to the
intermediate radial distance signal, the incremental velocity signal, and
the starting location radial distance signal, the modified increment
velocity signal representing the velocity of the tool centerpoint which
results in a relative velocity between the tool centerpoint and the
workpiece surface at the programmed velocity at the intermediate location
of the tool centerpoint.
5. A method for selectively, cooperatively controlling motion of a tool
centerpoint associated with the function element carried by a manipulator
and rotation of a workpiece carried by a positioner, the motion effected
by the manipulator being along a linear path intersecting the axis of
rotation of the workpiece, the motion being defined by input signals
representing starting and ending locations of the tool centerpoint
relative to a rectangular coordinate system associated with the
manipulator and starting and ending angular locations of the workpiece
relative to the axis of rotation of the workpiece, the manipulator and
positioner having movable members driven by actuators controlled by
servomechanism circuits, the relative motion of the tool centerpoint and
workpiece surface being effected at a velocity represented by an input
signal, and axial and radial limit distances relative to the workpiece
positioner being defined by further input signals, the method comprising
the steps of:
a. producing a velocity coordination status signal in response to the input
signals, the velocity coordination status signal representing the presence
of a starting location within an envelope defined by the axial and radial
limit distance input signals;
b. producing an effective linear distance signal representing the distance
resulting from the combination of tool centerpoint motion and workpiece
rotation;
c. producing an adjusted programmed velocity signal in response to the
effective linear distance signal and the programmed velocity signal, the
adjusted programmed velocity signal representing the velocity of the tool
centerpoint which results in a relative velocity between the tool
centerpoint and the workpiece surface equal to the programmed velocity;
d. iteratively producing incremental velocity signals in response to the
adjusted programmed velocity signal and the location coordinate and
rotation input signals, each incremental velocity signal representing the
velocity of the tool centerpoint during an iteration interval;
e. modifying the incremental velocity signals in proportion to the change
in radial distance of the tool centerpoint from the axis of rotation of
the workpiece between successive programmed locations;
f. producing intermediate location coordinate signals in response to the
modified incremental velocity signals, the intermediate location
coordinate signals representing coordinates relative to a rectangular
coordinate system associated with the manipulator of the tool centerpoint
and intermediate rotations of the workpiece; and
g. applying the intermediate location coordinate signals to the
servomechanism circuits to effect coordinated motion of the tool
centerpoint and the workpiece.
6. The method of claim 5 wherein the step of producing a velocity
coordination status signal further comprises the steps of:
a. producing transformed location coordinate signals in response to the
location coordinate input signals, the transformed location coordinate
signals representing coordinates of the tool centerpoint relative to a
rectangular coordinate system having its origin in the plane of the
positioner to which the workpiece is mounted and having one axis
substantially coincident with the axis of rotation of the workpiece;
b. producing a radial distance signal in response to the transformed
location coordinate signals, the radial distance signal representing the
radial distance from the axis of rotation of the workpiece to the starting
location coordinates;
c. comparing the transformed location coordinate signals and the radial
distance signal to the axial and radial limit distance input signals; and
d. producing the velocity coordination status signal in response to
detecting the presence of a starting location within the envelope defined
by the axial and radial limit distance signals.
7. The method of claim 6 wherein the axis of rotation of the workpiece is
not parallel to any of the rectangular coordinate axes associated with the
manipulator and further input signals define the rotations of the
coordinate axes of the manipulator coordinate system with respect to the
axes of the manipulator coordinate system and further define the location
of the origin of the positioner coordinate system relative to the
manipulator coordinate system and the step of transforming location
coordinate signals further comprises the steps of:
a. producing a translational displacement signal representing the linear
distance between the location and the origin of the positioner rectangular
coordinate system; and
b. producing transformed location coordinate signals in response to the
translational displacement signal and the positioner coordinate system
rotation input signals, the transformed location coordinate signals
representing coordinates of the location relative to the positioner
rectangular coordinate system.
8. A method for cooperatively controlling motion of the tool centerpoint
associated with the function element carried by a manipulator and rotation
of a workpiece carried by a positioner, the motion effected by the
manipulator being along a linear path intersecting the axis of rotation of
the workpiece, the motion being defined by input signals representing
coordinates of starting and ending locations of the tool centerpoint
motion relative to a rectangular coordinate system associated with the
manipulator, starting and ending orientations of the function element
through the tool centerpoint at the programmed locations and starting and
ending angular locations of the workpiece, the manipulator and positioner
having movable members driven by actuators controlled by servomechanism
circuits, the relative motion of the tool centerpoint and workpiece
surface being effected at a velocity represented by an input signal, the
method comprising the step of:
a. producing an effective linear distance signal representing the distance
resulting from the combination of tool centerpoint motion and workpiece
rotation;
b. producing an adjusted programmed velocity signal in response to the
effective linear distance signal and the programmed velocity signal, the
adjusted programmed velocity signal representing the velocity of the tool
centerpoint which results in a relative velocity between the tool
centerpoint and the workpiece surface equal to the programmed velocity;
c. iteratively producing incremental velocity signals in response to the
location coordinate input signals and the adjusted programmed velocity
signal, each incremental velocity signal representing the velocity of the
tool centerpoint during an iteration interval;
d. modifying the incremental velocity signals in proportion to the change
in radial distance of the tool centerpoint from the axis of rotation of
the workpiece between successive programmed locations;
e. producing intermediate location coordinate signals in response to the
modified incremental velocity signal, the intermediate location coordinate
signals representing coordinates relative to the manipulator rectangular
coordinate system of intermediate locations of the tool centerpoint and
intermediate orientations of the function element and intermediate angular
locations of the workpiece; and
f. applying the intermediate location coordinate signals to the servo
mechanism circuits to effect coordinated motion between the tool
centerpoint and the workpiece.
9. The method of claim 8 wherein the step of producing intermediate
location coordinate signals further comprises the step of:
a. producing a programmed distance signal representing the largest of the
linear distance traversed by the tool centerpoint, the effective arc
length swept by the function element through the programmed orientation
changes, and the arc length swept by the average radial distance of the
tool centerpoint from the axis of rotation of the workpiece between the
start and finish rotations of the workpiece;
b. producing coordinate component ratio signals, each coordinate component
ratio signal representing the quotient of the change in magnitude of a
coordinate and the programmed distance signal;
c. producing an incremental distance signal in response to the incremental
velocity signal and an iteration interval signal representing the period
between iterations, the incremental distance signal representing an
increment of motion occurring over the iteration period; and
d. producing coordinate component signals in response to the incremental
distance signal and the coordinate component ratios, the coordinate
component signals representing coordinate components of the incremental
distance.
10. The method of claim 9 wherein the axis of rotation of the workpiece is
not parallel to any of the coordinate axes of the rectangular coordinate
system associated with the manipulator and the step of modifying the
incremental velocity signals further comprises the steps of:
a. producing transformed coordinate signals representing coordinates of
programmed locations relative to a workpiece positioner rectangular
coordinate system having its origin in the plane of the positioner to
which the workpiece is mounted and one axis substantially coincident with
the axis of rotation of the workpiece.
b. producing intermediate radial distance signals in response to the
transformed location coordinate signals, the intermediate radial distance
signals representing the radial distance from the axis of rotation of the
workpiece to the intermediate tool centerpoint location; and
c. producing a modified increment velocity signal in response to the
intermediate radial distance signal, the increment velocity signal and the
starting location radial distance, the modified incremental velocity
signal representing the velocity of the tool centerpoint resulting in a
relative velocity between the tool centerpoint and the workpiece surface
equal to the programmed velocity at the intermediate location.
11. Apparatus for cooperatively controlling motion of a tool centerpoint
associated with a function element carried by a manipulator and rotation
of a workpiece carried by a positioner, the motion effected by the
manipulator being along a linear path intersecting the axis of rotation of
the workpiece, the motion being defined by input signals, the manipulator
and positioning device having movable members driven by actuators
controlled by servomechanism circuits, the relative motion of the tool
centerpoint and workpiece surface being effected at a velocity represented
by an input signal, the apparatus comprising:
a. means for storing input signals;
b. means responsive to the input signals for iteratively producing
incremental velocity signals, each incremental velocity signal
representing the velocity of the tool centerpoint during an iteration
interval;
c. means for modifying the incremental velocity signal in proportion to the
change in radial distance of the tool centerpoint from the axis of
rotation of the workpiece between successive iterations;
d. means responsive to the modified incremental velocity signal for
producing intermediate location coordinate signals representing
coordinates of an intermediate location along the linear path of the tool
centerpoint relative to a rectangular coordinate system associated with
the manipulator and an intermediate angular coordinate of the workpiece
rotation relative to the axis of rotation of the workpiece;
e. means for applying the intermediate location coordinate signals to the
servomechanism circuits to effect coordinated motion of the tool
centerpoint and the workpiece at a relative velocity defined by the
velocity input signal.
12. The apparatus of claim 11 wherein the means for producing intermediate
location signals further comprises:
a. means for producing a programmed distance signal representing the larger
of the linear distance traversed by the tool centerpoint and the arc
length swept by the average radial distance of the tool centerpoint from
the axis of rotation of the workpiece through the angular change of
location of the workpiece;
b. means for producing coordinate component ratio signals, each coordinate
component ratio signal representing the quotient of the change in
magnitude of a selected coordinate and the programmed distance signal;
c. means responsive to the modified incremental velocity signal and an
iteration interval signal representing the period between iterations for
producing an incremental distance signal representing an increment of
motion occurring during an iteration; and
d. means responsive to the incremental distance signal and the coordinate
component ratio signals for producing the coordinate component signals
representing coordinate components of the incremental distance.
13. The apparatus of claim 12 wherein the input signals define coordinates
of starting and ending locations of the tool centerpoint motion relative
to the manipulator rectangular coordinate system and the workpiece
rotation and the apparatus further comprises:
a. means for producing an effective linear distance signal representing the
distance resulting from the combination of tool centerpoint motion and
workpiece rotation; and
b. means responsive to the effective linear distance signal for producing
an adjusted programmed velocity signal representing the velocity of the
tool centerpoint which results in a relative velocity between the tool
centerpoint and the workpiece surface equal to the programmed velocity.
14. The apparatus of claim 13 wherein the axis of rotation of the workpiece
is not parallel to any of the coordinate axes defining locations of the
tool centerpoint and the apparatus further comprises means for producing
transformed coordinate signals representing coordinates of tool
centerpoint locations relative to a workpiece positioner rectangular
coordinate system having its origin in the plane upon which the workpiece
is mounted and having one axis substantially coincident with the axis of
rotation of the workpiece.
15. The apparatus of claim 14 wherein the means for modifying the
incremental velocity signals further comprises:
a. means responsive to the transformed coordinate signals for producing an
intermediate radial distance signal representing the radial distance from
the axis of rotation of the workpiece to the intermediate tool centerpoint
location; and
b. means responsive to the intermediate radial distance signal, the
increment velocity signal and the radial distance signal of the starting
location for producing a modified increment velocity signal.
16. Appratus for cooperatively controlling motion of a tool centerpoint
associated with a function element carried by a manipulator and rotation
of a workpiece carried by a positioner, the motion effected by the
manipulator being along a linear path oblique to the axis of rotation of
the workpiece and having a component tangent to an arc swept by a radius
from the axis of rotation of the workpiece to the tool centerpoint, the
motion being defined by input signals representing starting and ending
locations of the tool centerpoint relative to a rectangular coordinate
system associated with the manipulator and the starting and ending angular
locations of the workpiece, the manipulator and positioner having movable
members driven by actuators controlled by servomechanism circuits, the
relative motion of the tool centerpoint and workpiece surface being
effected at a velocity represented by an input signal, the apparatus
comprising:
a. means for storing input signals;
b. means responsive to the input signals for producing an effective linear
distance signal representing the distance resulting from the combination
of tool centerpoint motion and workpiece rotation;
c. means responsive to the effective linear distance signal for producing
an adjusted programmed velocity signal representing the velocity of the
tool centerpoint which results in a relative velocity between the tool
centerpoint and the workpiece surface equal to the program velocity;
d. means responsive to the input signals and the adjusted velocity signal
for iteratively producing incremental velocity signals, each incremental
velocity signal representing the velocity of the tool centerpoint during
an iteration interval;
e. means for modifying the incremental velocity signals in proportion to
the change in radial distance of the tool centerpoint from the axis of
rotation of the workpiece between successive iterations;
f. means responsive to the modified incremental velocity signal for
producing intermediate location coordinate signals representing
coordinates relative to the manipulator coordinate system of an
intermediate location along the linear path of the tool centerpoint and
further representing intermediate rotations of the workpiece; and
g. means for applying the intermediate location coordinate signals to the
servo mechanism circuits to effect coordinated motions between the tool
centerpoint and the workpiece.
17. The apparatus of claim 16 wherein the means for producing an effective
linear distance signal further comprises:
a. means for producing a tangential deviation signal representing the
tangential distance between two successive programmed locations of the
tool centerpoint;
b. means for producing an arc distance signal representing the arc length
swept by the average radial distance of the tool centerpoint from the axis
of rotation of the workpiece when rotated through the programmed angular
change of the workpiece;
c. means responsive to the tangential deviation signal and the arc distance
signal for comparing the magnitudes thereof; and
d. means responsive to the comparing means for producing an effective
linear distance signal irrespective of the relative magnitudes of the
tangential deviation signal and arc length signal.
18. The apparatus of claim 17 wherein the means for producing intermediate
location signals further comprises:
a. means for producing a programmed distance signal representing the larger
of the linear distance between two successive programmed locations of the
tool centerpoint and the arc length represented by the arc distance
signal;
b. means for producing coordinate component ratio signals representing the
quotient of the change in magnitude of the coordinate component and the
programmed distance signal;
c. means responsive to the increment velocity signal and an iteration
interval signal representing the period between iterations for producing
an incremental distance signal representing an increment of motion
occurring over the iteration period; and
d. means responsive to the incremental distance signal and the coordinate
component ratios for producing coordinate component signals representing
coordinate components of the incremental distance.
19. The apparatus of claim 18 wherein the axis of rotation of the workpiece
is not parallel to any of the coordinate axes defining programmed
locations and the apparatus further comprises means for producing
transformed coordinate signals representing coordinates of programmed
locations relative to a rectangular coordinate system having its origin in
the plane of the positioner to which the workpiece is mounted and having
one axis substantially coincident with the axis of rotation of the
workpiece.
20. The apparatus of claim 19 wherein the means for modifying the
incremental velocity signals further comprises:
a. means responsive to the transformed coordinate signals for producing an
intermediate radial distance signal representing the radial distance from
the axis of rotation of the workpiece to the intermediate tool centerpoint
location; and
b. means responsive to the intermediate radial distance signal, the
increment velocity signal and the starting location radial distance signal
for producing a modified increment velocity signal.
21. Apparatus for selectively, cooperatively controlling motion of a tool
centerpoint associated with a function element carried by a manipulator
and rotation of a workpiece carried by a positioner, the motion effected
by the manipulator being along a linear path intersecting the axis of
rotation of the workpiece, the motion being defined by input signals
representing starting and ending locations of the tool centerpoint
relative to a rectangular coordinate system associated with the
manipulator and the starting and ending angular coordinates of the
workpiece relative to the axis of rotation thereof, the manipulator and
positioner having movable members driven by actuators controlled by
servomechanism circuits, the relative motion of the tool centerpoint and
workpiece surface being effected at a velocity represented by input
signals, further input signals defining axial and radial limit distances
relative to the axis of rotation of the workpiece, the apparatus
comprising:
a. means for storing input signals;
b. means responsive to the input signals for producing a velocity
coordination status signal representing the presence of a starting
location within an envelope defined by the axial and radial limit distance
signals;
c. means responsive to the velocity coordination status signal for
producing an adjusted velocity signal representing the velocity of the
tool centerpoint resulting in a velocity thereof relative to the workpiece
surface equal to the programmed velocity;
d. means responsive to the location defining input signals and the adjusted
velocity signals for iteratively producing incremental velocity signals,
each incremental velocity signal representing the velocity of the tool
centerpoint during an iteration interval;
e. means for modifying the incremental velocity signals in proportions to
the change in radial distance of the tool centerpoint from the axis of
rotation of the workpiece between successive iterations;
f. means responsive to the modified incremental velocity signals for
producing intermediate location coordinate signals representing
coordinates relative to a rectangular coordinate system associated with
the manipulator of an intermediate location along the linear path of the
tool centerpoint and an intermediate angular coordinate of the workpiece
rotation relative to the axis of rotation thereof; and
g. means for applying the intermediate coordinate signals to the servo
mechanism circuits to effect coordinated motion of the movable members.
22. The apparatus of claim 21 wherein the means for producing the velocity
coordination status signal further comprises:
a. means responsive to the programmed location input signals for producing
transformed programmed location coordinate signals representing
coordinates of the tool centerpoint relative to a rectangular coordinate
system having its origin in the plane of the positioner to which the
workpiece is affixed and having an axis substantially coincident with the
axis of rotation of the workpiece;
b. means responsive to the transformed programmed location coordinate
signals for producing a starting location radial distance signal
representing the radial distance from the axis of rotation of the
workpiece to a starting location of the tool centerpoint;
c. means for comparing the transformed programmed location coordinate
signals to the axial and radial limit distance input signals; and
d. means responsive to the comparing means for producing a velocity
coordination status signal in response to detecting the presence of the
starting location within the envelope defined by the axial and radial
limit distance signals.
23. The apparatus of claim 22 wherein the axis of rotation of the workpiece
is not parallel to any of the coordinate axis defining programmed
locations, and further input signals define rotations of the workpiece
positioner coordinate system with respect to the manipulator rectangular
coordinate system and the means for producing transformed coordinate
signals further comprises:
a. means for producing translational displacement signals representing the
linear distance between the location defined by the manipulator
coordinates and the origin of the positioner rectangular coordinate
system; and
b. means responsive to the translational displacement signals and the
positioner coordinate system rotation input signals for producing the
transformed coordinate signals.
24. An apparatus for cooperatively controlling motion of the tool
centerpoint associated with the function element carried by a manipulator
and rotation of a workpiece carried by a positioner, the motion effected
by the manipulator being along a linear path intersecting the axis of
rotation of the workpiece, the motion being defined by input signals
representing starting and ending locations of the tool centerpoint motion
and starting and ending orientations of the function element through the
tool centerpoint and starting and ending angular positions of the
workpiece, the manipulator and positioner having movable members driven by
actuators controlled by servomechanisms circuits, the relative motion of
the tool centerpoint and workpiece surface being effected at a velocity
represented by input signals, the apparatus comprising:
a. means for storing input signals;
b. means responsive to the input signals for iteratively producing
incremental velocity signals, each incremental velocity signal
representing the velocity of the tool centerpoint during an iteration
interval;
c. means for modifying the incremental velocity signals in proportion to
the change in radial distance of the tool centerpoint from the axis of
rotation of the workpiece between successive iterations;
d. means responsive to the modified incremental velocity signals for
producing intermediate location coordinate signals representing
coordinates relative to a rectangular coordinate system associated with
the manipulator of an intermediate location along the linear path of the
tool centerpoint and intermediate changes of orientation of the function
element through the tool centerpoint and intermediate rotations of the
workpiece; and
e. means for applying the intermediate location, orientation and rotation
coordinate signals to the servomechanism circuits to effect coordinated
motion between the tool centerpoint and the workpiece.
25. The apparatus of claim 24 wherein the means for producing intermediate
location signals further comprises:
a. means for producing a program distance signal representing the largest
of; the linear distance between two programmed locations; and the
effective arc length swept by the function element between two programmed
orientation; and the arc length swept by the average radial distance of
the tool centerpoint from the axis of rotation of the workpiece through
the programmed rotation of the workpiece;
b. means for producing coordinate component ratio signals representing the
quotient of the change in magnitude of the coordinate component and the
programmed distance signal;
c. means responsive to the increment velocity signal and an iteration
interval signal representing the period between iterations for producing
an incremental distance signal representing an increment of motion
occurring over the iteration period; and
d. means responsive to the incremental distance signal and the coordinate
component ratios for producing coordinate component signals representing
coordinate components of the incremental distance.
26. The apparatus of claim 25 wherein the axis of rotation of the workpiece
is not parallel to any of the coordinate axes defining programmed
locations of the tool centerpoint relative to the manipulator and the
apparatus further comprises means for producing transformed coordinate
signals representing coordinates of programmed locations relative to a
rectangular coordinate system associated with the workpiece positioner
having its origin in the plane of the positioner to which the workpiece is
mounted and having an axis coincident with the axis of rotation of the
workpiece.
27. The apparatus of claim 26 wherein the means for modifying the
incremental velocity signals further comprises:
a. means responsive to the transformed coordinate signals for producing an
intermediate radial distance signal representing the radial distance from
the axis of rotation of the workpiece to the intermediate tool centerpoint
location; and
b. means responsive to the intermediate radial distance signal, the
incremental velocity signal, and the starting location radial distance
signal for producing a modified increment velocity signal. |
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Claims |
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Description |
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BACKGROUND OF THE INVENTION
This invention relates generally to machine control. In particular this
invention relates to coordinated motion of a tool carried by a program
controlled manipulator with motion of a workpiece carried by a program
controlled positioner.
Some applications of program control manipulators require, in addition to
the motion imparted to the tool carried by the manipulator, that the
workpiece be rotated to provide continuous processing over surface
segments which cannot simultaneously be presented in the most advantageous
attitude. For example, where seam joining or sealing is involved, best
results are achieved when gravity assists the deposition of material.
However, where the seam traverses a contour on a curved plane or across
multiple flat planes, it is not always possible to achieve a suitable
relative orientation of workpiece and tool without rotating the workpiece.
The coordination of tool motion and workpiece motion presents difficulties
in program creation as the effective relative velocity of workpiece and
tool may vary with position as the desired relative motions are executed.
In some previously known control systems, all motions of the manipulator
were affected if there was a simultaneous motion of the workpiece, even if
the combined motions were not being executed to perform work on the
workpiece. Thus, prepositioning moves from a rest or load location to a
process start location would be affected by the motion coordinating
algorithms.
Further, in previously known systems, program creation required that the
programmer enter the effective path distance resulting from the combined
motions. As manipulator programs have traditionally been created by a
process of manually commanded positioning and data recording, the span
length computation required for coordinated motion conflicts with the
traditional program creation process.
It is, therefore, one object of the present invention to provide a
manipulator control for coordinating motion of a manipulator with rotation
of a workpiece in response to input signals defining the beginning and end
points of motions of both the manipulator and the workpiece positioner and
the relative velocity between a tool carried by the manipulator and the
workpiece surface.
It is a further object of the present invention to provide a control for a
program controlled manipulator for coordinating linear motions effected by
the manipulator with workpiece rotations when these simultaneous motions
are initiated within a predefined envelope describing proximity of a tool
centerpoint to the workpiece positioner.
It is a still further object of the present invention to provide a control
for a program controlled manipulator for coordinating the linear motion
effected by the manipulator with workpiece rotation where the radius of
the workpiece changes within the span length traversed by the tool
centerpoint.
It is a still further object of the present invention to provide a control
for a program controlled manipulator for coordinating the linear motion
effected by the manipulator and workpiece rotation wherein the effective
relative motion of the tool centerpoint to the workpiece surface includes
a substantial tangential component.
Further objects and advantageous of the present invention shall become
apparent from the appended drawings and the description thereof.
SUMMARY OF THE INVENTION
In accordance with the aforesaid objects, a control for a program
controlled manipulator and workpiece positioner is provided for
coordinating linear motion of a tool centerpoint of a function element
carried by the manipulator and rotation of the workpiece effected by the
workpiece positioner. Simultaneous linear motion of the tool centerpoint
and workpiece rotation which are initiated such that the tool centerpoint
is located within a predefined envelope relative to the workpiece mounting
table are subject to velocity coordination. The control computes the
effective linear distance using input signals representing the end points
of the linear motion of the tool centerpoint and the rotation of the
workpiece. The control accommodates programmed motions having a
substantial tangential component. The effective linear distance is used to
produce an adjusted velocity signal to effect relative velocity between
the tool centerpoint and the workpiece surface at the programmed velocity.
The control iteratively produces increments of tool centerpoint motion and
workpiece rotation which are effected over an increment interval period.
The relative velocity for each increment interval period is modified to
accommodate changing workpiece surface velocity occurring as a result of
motion of the tool center point relative to a workpiece portion having a
varying radius.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 shows an industrial manipulator and the schematic connection thereof
to a control.
FIG. 2 is a block diagram of the control of FIG. 1.
FIG. 3(a) is a schematic representation of the manipulator shown in the
rectangular coordinate system defining coordinates of the programmed
locations.
FIGS. 3(b) and 3(c) show the axes of motion of the manipulator wrist and
the associated orientation angles defined by input signals.
FIG. 3(d) shows the workpiece positioner and the rectangular coordinate
system associated therewith.
FIGS. 4(a) through 4(c) depict the motion effected by the controlled
manipulator in an automatic mode of operation.
FIGS. 4(d) and 4(e) illustrate relative motions of the manipulator and
workpiece.
FIGS. 5(a) and 5(b) are flow charts of the two principle control procedures
effecting motion control.
FIGS. 6(a) through 6(f) are flow charts of subroutines and major segments
of the flow chart of FIG. 5(a).
FIGS. 7(a) through 7(e) are flow charts of subroutines and major segments
of the flow chart of FIG. 6
FIGS. 8(a) through 8(c) are flow charts of procedures for modifying the
incremental velocity value according to the relative velocity between the
tool centerpoint and the workpiece.
DESCRIPTION OF THE PREFERRED EMBODIMENT
For purposes of illustrating the present invention, a manipulator and
control shown in the accompanying drawings shall be described in detail.
This manipulator and control correspond to those manufactured by
Cincinnati Milacron Industries Inc., the assignee of the present
invention. While the detailed description of the preferred embodiment
shall necessarily reflect the actual implementation, such details should
not be construed as limitations on the present invention which is defined
by the appended claims.
Referring to FIG. 1, a manipulator 10 is shown carrying a tool 50 and
connected to a control 60. The manipulator is constructed so that the
motion of its members describe axes of rotation. The first of these axes
is called the base axis and is defined by rotation of the plate 16 about a
vertical axis through its center. An upper arm 18 rotates about a
horizontal axis, called the shoulder axis, through the center of pivot 20
intersecting the vertical axis of rotation of the base. A forearm 22
rotates about a horizontal axis called the elbow axis, through the pivot
24. Mounted at the end of forearm 22 is wrist 32 which provides three
additional axes of rotation. The first of these is rotation of segment 33
about an axis lying parallel to or coincident with the longitudinal center
line of forearm 22; the second is rotation of segment 31 about an axis
perpendicular to the slice separating the inner segment 33 from the outer
segment 31; and, the third is rotation of face plate 44 about an axis
orthogonal thereto and through its center.
Rotations of members about the base, shoulder, and elbow axes are
sufficient to define locations within the operating volume of the
manipulator of a tool centerpoint 48 associated with the tool 50.
Rotations of the inner and outer segments of the wrist 32 and the face
plate 44 control orientations of the tool at the programmed locations in
accordance with programmed orientation angles. Each of the six axes of
motion is servocontrolled by connection of command and feedback signals to
servocontrol 64 of the control 60. Operation of the tool 50 is
accomplished by a machine interface 66 which responds to the programmed
cycle of operation controlled by the cycle control 62. The cycle control
62 operates upon stored location, velocity, and function data to produce
control signals for the servocontrol 64 and the machine interface 66. As
shown, the tool 50 is a welding torch and control of the welding process
is effected through the machine interface in response to stored function
signals. Other tools for joining, cutting, cleaning, polishing, grasping,
and so forth may be substituted for the torch shown and controlled through
the machine interface 66.
Rotations of the upper arm and forearm about their respective axes are
achieved by the linear motions of the screws 30 and 25 through the nuts 28
and 26. Rotation of the nuts is imparted through pulleys 29 and 27
respectively by drive motors not shown. Rotation of plate 16 about its
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