Apparatus and method for positioning tooling

Apparatus and method for positioning tooling for operation on a curved workpiece wherein a gantry beam assembly having a movable head assembly thereon carrying tooling is pivotally connected on a pivot axis to a pair of spaced apart pedestals each having a longitudinal axis disposed substantially perpendicular to the pivot axis and wherein the workpiece is supported on a fixture between the pedestals and so that the gantry beam assembly extends along the workpiece. The pivot axis of the gantry beam assembly is moved along the longitudinal axes of the pedestals, the pivot axis of the gantry beam assembly is moved along a path substantially perpendicular to the longitudinal axes of the pedestals and the head assembly is moved along the gantry beam assembly. The foregoing operations move the head assembly relative to the workpiece enabling the tooling to perform operations thereon. The gantry beam assembly is pivoted about the pivot axis and the head assembly is pivoted about an axis substantially perpendicular to the pivot axis for normalization of the head assembly relative to the workpiece. The gantry beam assembly can be tilted along a plane substantially parallel to the longitudinal axes of the pedestals to accommodate frustoconical and similar shaped workpieces. The gantry beam assembly can be provided with gimbal connections to the pedestals to provide additional degrees of freedom for operation on workpieces having compound curvatures.

BACKGROUND OF THE INVENTION
 The present invention relates generally to positioning tooling with respect
 to a workpiece, and more particularly to an apparatus for positioning
 tooling with respect to a curvilinear workpiece.
 Presently, the installation of fasteners during the assembly of aircraft
 wings, fuselages, and other components requires large machines, including
 conventional C-shaped tooling machines. Conventional C-shaped tooling
 machines may be equipped to drill, upset rivets, seal riveted joints, and
 perform other work on the constituent parts of the aircraft components.
 While such C-shaped machines operate effectively with workpieces of
 certain sizes and configurations, they encounter limitations wherein due
 to the configuration and/or size of the workpiece, access to the opposite
 sides thereof is limited. Also, the use of these C-shaped machines can
 require very complicated structures and procedures to support the
 workpiece in order to accommodate the same, and can also require the
 workpiece to be constantly repositioned, which consumes valuable
 production time. There is thus a need for an apparatus for positioning
 tooling overcomes such limitations.
 The present invention provides a novel solution to the long felt need for
 an apparatus for positioning tooling with respect to large curvilinear
 workpieces.
 SUMMARY OF THE INVENTION
 The present invention provides apparatus and method for positioning tooling
 for operation on a curved workpiece wherein a gantry beam assembly having
 a movable head means thereon carrying tooling is pivotally connected on a
 pivot axis to a pair of spaced apart pedestals each having a longitudinal
 axis disposed substantially perpendicular to the pivot axis and wherein
 the workpiece is supported on a fixture between the pedestals and so that
 the gantry beam assembly extends along the workpiece. The pivot axis of
 the gantry beam assembly is moved along the longitudinal axes of the
 pedestals, the pivot axis of the gantry beam assembly is moved along a
 path substantially perpendicular to the longitudinal axes of the pedestals
 and the head means is moved along the gantry beam assembly. The foregoing
 operations move the head means relative to the workpiece enabling the
 tooling to perform operations thereon. The gantry beam assembly is pivoted
 about the pivot axis and the head means is pivoted about an axis
 substantially perpendicular to the pivot axis for normalization of the
 head means relative to the workpiece. The gantry beam assembly can be
 tilted along a plane substantially parallel to the longitudinal axes of
 the pedestals to accommodate frustoconical and similar shaped workpieces.
 The gantry beam assembly can be provided with gimbal connections to the
 pedestals to provide additional degrees of freedom for operation on
 workpieces having compound curvatures.
 The foregoing and additional advantages and characterizing features of the
 present invention will become clearly apparent upon a reading of the
 ensuing detailed description together with the included drawing.

DETAILED DESCRIPTION OF THE INVENTION
 The present invention, illustrated in the drawings, provides an apparatus
 10 for positioning tooling which may be adapted to carry tool assemblies
 for drilling, fastener (rivet) upsetting, sealant dispensing, rivet
 shaving, measuring and inspecting, routing and other tool assemblies known
 to those skilled in the art which are employed to perform operations on a
 workpiece 12. Workpiece 12, having a single panel or multi-panels, has a
 generally curved and/or compound curvature, and is supported in fixture
 14, having an upper framework 16 and a lower supporting base 18 which
 rests on a surface 20, which may be the floor of the factory. Workpiece 12
 has a longitudinal axis 22 which, in the present illustration, is disposed
 substantially parallel to the plane of supporting surface 20. Workpiece 12
 is illustrated as an airplane fuselage section, generally cylindrically
 shaped and having seven panels about its circumference, it being
 understood that the apparatus 10 of the present invention will work
 equally well with fuselage sections having less or greater than seven
 panels about their circumference. Also, it is understood that the present
 invention will work equally well with other curvilinear workpieces, that
 is with workpieces which are curved in a first direction extending along a
 plane substantially perpendicular to the longitudinal axis of the
 workpiece and which are curved in a second direction extending along a
 plane substantially parallel to the workpiece longitudinal axis. In
 addition, although a fuselage section is depicted in the drawing figures,
 the present invention will work equally well with other arcuate or curved
 workpieces. Also, while the present invention is particularly advantageous
 for work on curved workpieces, it can be used with flat workpieces
 including those having flat sections spliced at an angle or angled joint.
 Referring now to FIG. 1 and the enlarged views of FIGS. 9 and 10, the
 apparatus 10 of the present invention for positioning tooling comprises a
 carriage 28 supporting a first pedestal 30 and a carriage 48 supporting a
 second pedestal 50, both of which carriages 28, 48 are controllably
 movable on a pair of ground tracks 32, 34 which extend along surface 20 in
 a mutually parallel relation. Ground tracks 32, 34 extend along a
 direction designated the Y-axis, seen also in FIG. 8. Controlled drive
 means on the Y-axis carriages 28, 48 engage tracks 32 and 34 in a manner
 which will be described. Movement of carriages 28, 48 also is supported by
 rails 36 and 38, located outwardly of tracks 32, 34 and which receive
 wheels or rollers on carriages 28, 48. Perpendicular to the Y-axis, and
 defined along the longitudinal axis of the first pedestal 30 is the
 W-axis, and defined along the longitudinal axis of the second pedestal 50
 is the Z-axis, as shown in FIG. 9. In the illustrated arrangement, the
 Y-axis is generally horizontal, and the W-axis and Z-axis are generally
 vertical. As shown in FIGS. 1, 9, and 10 each gantry pedestal 30 and 50 is
 located outside of the fuselage section 12, i.e. spaced outwardly from the
 opposite ends of workpiece 12.
 A gantry beam assembly 70, which in the embodiment of FIGS. 1-18 comprises
 a first beam 72 and a second beam 74, is pivotally mounted to the first
 and second pedestals 30 and 50, respectively. The first beam 72 and second
 beam 74 are in spaced generally parallel relation to one another and
 disposed with the longitudinal axes thereof substantially perpendicular to
 the W and Z axes. An X-axis, shown in FIG. 9, extends in a direction
 substantially parallel to the longitudinal axes of beams 72 and 74. The
 X-axis also extends substantially parallel to the longitudinal axis 22 of
 workpiece 12. The first and second beams 72 and 74, respectively, are
 attached at opposite ends thereof to first and second beam mounts 76 and
 78, respectively. The first and second beam mounts 76 and 78, in turn, are
 pivotally connected to the first and second pedestals 30 and 50,
 respectively, by first and second pivot assemblies or shafts 80 and 82,
 respectively. An A-axis is defined along the common longitudinal axis of
 the first and second pivot assemblies 80 and 82 respectively, seen at 81
 in FIG. 9. Axis 81 is the pivot axis of gantry assembly 70. First and
 second controlled rotating means 104 and 106, respectively, are connected
 to the first and second pivot assemblies 80 and 82, respectively, to
 rotate the gantry assembly 70 about the A-axis. Such rotation about the
 A-axis may be plus or minus about 115 degrees, as depicted in FIG. 8. The
 rotating means 104 and 106 each can comprise commercially available rotary
 actuators such as the combination of a pulsed electric meter motor and a
 reducing gear box.
 The first and second gantry pedestals 30 and 50, respectively, are equipped
 with first and second elevator means or carriages 42 and 52 respectively,
 which support the pivot assemblies 80 and 82 and rotating means 104 and
 106, for controllably moving the gantry assembly 70 along the W-axis and
 Z-axis, respectively, i.e., vertically as viewed in the drawings. In
 particular, simultaneous and synchronized vertical movement of elevators
 42 and 52 moves gantry assembly 70 in a vertical direction while
 maintaining the gantry 70 in a horizontal disposition as viewed in the
 drawings. In addition, one of the pivot assemblies, for example pivot
 assembly 80, is further equipped with a corresponding slip joint mechanism
 98, which permits the gantry assembly 70 to be tilted. One illustrative
 arrangement for implementing slip joint mechanism 98 is a linear bearing
 set designated 100 in FIG. 10 of the type commercially available from THK
 or NSK. For example, the second elevator means or carriage 52 may be
 actuated to thus move the second pivot assembly 82 along the Z-axis, while
 the first elevator means or carriage 42 is not actuated, thus holding the
 first pivot assembly 80 stationary on the W-axis. The slip joint mechanism
 98 accommodates tilting of gantry 70 while allowing pedestal 30 to remain
 in a vertical position. The result of this skewing of the Z-axis relative
 to the W-axis defines a b-axis movement which rotates about the Y-axis,
 described above. This is illustrated in FIG. 18 which shows apparatus 10
 operating on a frustoconical workpiece 12.sup.1. The above described
 skewing may be to such a degree that the b-axis rotation is plus or minus
 15 degrees relative to the Y-axis. Such skewing or b-axis rotation about
 the Y-axis provides versatility, so that gantry 70 may be tilted to
 accommodate curvilinear workpieces having compound curves and the like,
 i.e., curvature along the longitudinal axis of the workpiece. Only one of
 the pivot assemblies, in the foregoing illustration assembly 80, is
 provided with a slip joint so that proper reference/location information
 on gantry 70 can be maintained for the system control. The elevators or
 carriages 42 and 52 are indexed on linear bearings and are driven by dual
 ball screw and nut arrangements operated by dual synchronized servo
 motors. A drive motor 58, ball screw 60 and nut 62 is provided for
 carriage 42 as shown in FIG. 10, and a drive motor 64, ball screw 66 and
 nut 68 is provided for carriage 52 as shown in FIGS. 7, 8, and 10. Each
 axis is programmable with encoder feedback to the system control.
 As seen in FIGS. 2, 11, and 12, the Y-axis carriages 28 and 48 are equipped
 with drive means 44 and 54, respectively, to accomplish movement of the
 pedestals 30 and 50, respectively, and hence apparatus 10, along the
 ground tracks 32 and 34, that is along the Y-axis. Drive means 44 and 54
 include synchronized servo motors for operating pinions which engage
 tracks 32 and 34 in a rack and pinion type arrangement. Information on the
 Y-axis position is obtained by encoder feedback to the system control.
 Carriages 28 and 30 can be equipped with other controlled drive means,
 such as ball screw and nut arrangements driven by controlled electric
 motors or linear electric motor drives. The foregoing movement of
 carriages 28 and 48 and with them the pedestals 30 and 50, respectively,
 moves the axes of pivot shafts 80 and 82 and thus the pivot axis 81 of
 gantry 70 along the Y axis. While the foregoing arrangement is preferred,
 the pivot axis of gantry 70 could be moved along the Y axis by a different
 arrangement wherein pedestals 30 and 50 remain stationary. A first
 traverse beam assembly would be carried by elevator 42 of pedestal 30 and
 a second traverse beam assembly would be carried by elevator 52 of
 pedestal 50. The transverse beam assemblies would be disposed generally
 horizontally in a setup of the type shown in FIGS. 1 and 2 and would
 extend in the direction of the Y-axis. Pivot shaft 80, slip joint 98 and
 rotary actuator 104 would be connected to a carriage component mounted in
 or on the first traverse beam for movement along the beam and hence along
 the Y axis by suitable controlled drive means such as a rack and pinion
 drive or ball screw and nut drive. Similarly, pivot shaft 82 and rotary
 actuator 106 would be connected to a carriage component mounted in or on
 the second transverse beam for movement along the beam and hence along the
 Y axis by suitable controlled drive means such as a rack and pinion drive
 or ball screw and nut drive. As a result, the pivot axis 81 of gantry 70
 is moved along the Y axis but with the pedestals 30 and 50 remaining
 stationary.
 The apparatus 10 for positioning tooling further comprises first head means
 83 in a carriage 84 movably carried by the first beam 72 and second head
 means 85 in a carriage 86 movably carried by the second beam 74. Each of
 the head means 83, 85 contain tooling. For example, tools typically
 carried by head means 83 include a drill, fastener bucking tool, shave
 tool, sealant applicator, hole probe, router and vision system camera.
 Head means 85 typically carries a fastener upset tool. Each of the
 carriages 84 and 86 is movably supported by bearing/guide tracks or linear
 guide bearings on each of the first and second beams 72 and 74
 respectively, for movement along the X-axis. A pair of such tracks 110 and
 112 is shown, for example, in FIGS. 2, 11, and 15 on first beam 72. One
 such track 114 on beam 74 is shown, for example in FIGS. 1, 9, and 17.
 Bearings 116 on carriage 84 operatively engage tracks 110 and 112 as shown
 in FIGS. 13 and 15. Each of the carriages 84 and 86 is driven along the
 first and second beams 72 and 74, respectively, by a rack and pinion type
 drive arrangement. For example, as shown in FIG. 16, pinion 120 driven by
 motor 122 on carriage 84 engages a rack 124 extending along beam 72. A
 similar rack and pinion drive arrangement is provided for the carriage 86,
 the rack being shown, for example at 126 in FIG. 1. The foregoing can be
 implemented with integral rack and rail assemblies commercially available
 from THK under designation GSR-35 which advantageously simplifies
 machining and alignment. Operation of the X-axis drive motors on the
 carriages 84 and 86 is synchronized and controlled by the machine control
 system 230 described below, with position location and synchronized
 feedback utilizing encoders. An alternative drive arrangement could
 include a controlled linear electric motor. The first and second beams 72,
 74 are of sufficient length to provide a park position of carriages 84, 86
 beyond one end of workpiece 12, i.e., the left-hand end as viewed in the
 drawings to prevent any interference with the workpiece during loading and
 unloading in the fixture 14.
 Referring to FIG. 15, the first head means 83 and carriage 84 are shown in
 detail. The carriage 84 includes a top wall 134, depending outer side
 walls 136 and 138, and a pair of inner walls 140 and 142 spaced from walls
 136, 138 and joined thereto by bottom wall portions 144 and 146. Inner
 walls 140 and 142 are joined together by an intermediate wall 148.
 Carriage 84 thus is in a straddling relation to beam 72 as shown in FIG.
 15 where beam 72 has a top or base 150 and depending flanges 152 and 154.
 In addition to the combination of tracks 110, 112 and bearings 116,
 movement of carriage 84 along beam 72 also is guided by bearings 160 on
 carriage walls 140, 142 which engage tracks 162 on beam flanges 152 and
 154.
 As shown in FIG. 15, head 83 is provided with a pressure foot bushing 164
 well known to those skilled in the art, and each tool such as tool 165
 illustrated in FIG. 15 is moved toward and away from the workpiece in a
 known manner by suitable motive means which can be hydraulic or which can
 be electric such as a roller screw actuator shown and described in U.S.
 Pat. No. 5,829,115 issued Nov. 3, 1998, the disclosure of which is hereby
 incorporated by reference.
 Also provided on carriage 84 are a plurality of fastener cassettes 168
 which hold a supply of fasteners or rivets, and communicate with tool
 assembly 132 via a rivet feed arrangement (not shown) so as to deliver
 rivets thereto. Different types or sizes of fasteners can be carried in
 the different cassettes 168. Such rivet feed arrangements are well known
 in the art. Carrying a supply of fasteners or rivets on the carriage 84
 advantageously avoids having to transport rivets to head means 84 via
 tubes from a relatively remote storage location on another part of the
 machine which is particularly advantageous in view of the large size of
 the workpiece 12. Top wall 134, sidewalls 136, 138 and bottom walls 144,
 146 of carriage 84 are provided to accommodate fastener cassettes 168 and
 can be eliminated if the cassettes are not utilized. Then, carriage 84
 would include simply the spaced walls 140, 142.
 Carriage 84 also is provided with means for moving the head assembly 83
 containing tooling about an axis generally perpendicular to the
 longitudinal axis of the workpiece. This axis designated the b.sup.1 -axis
 and also is perpendicular to the X-axis. Such b.sup.1 -axis movement is
 provided in both carriages 84 and 86 for allowing the tool assembly heads
 83, 85 carried thereby to be positioned for normalization against the
 surface of workpiece 12. Such b.sup.1 -axis movement is in the
 neighborhood of about 18 degrees, for example. Referring to FIG. 15, the
 foregoing b.sup.1 -axis movement in head means 83 is provided by bearings
 170 on the head means 83 which ride in curvilinear ways or tracks 172 on
 carriage inner walls 140 and 142, respectively. The fixed curved rails 172
 and traveling bearings 170 comprise a curvilineal bearing set commercially
 available from THK. A ball screw drive 180, including a servo motor, and
 nut 182 combination on carriage intermediate wall 148 and on head 83
 causes relative movement between the two components which is programmable
 or under closed loop normality sensor control. This is also illustrated in
 FIG. 16 where it is seen that nut 182 is connected by member 184 to
 bearing 170, and as nut 182 advances along the ball screw shaft, bearing
 170 moves along track 172 to move head 83 about the b.sup.1 axis.
 Beam 74, shown in further detail in FIG. 17, includes a base 190 and
 upstanding flanges 192 and 194. Carriage 86 is movable within beam 74 and
 includes a bottom wall 204 and upstanding walls 206 and 208. Movement of
 carriage 86 along within beam 74 is effected by a pinion 210 driven by
 motor 212 on carriage 86 and which engages rack 126 extending along beam
 74. The linear movement of carriage 86 along beam 74 is guided by bearings
 216 on carriage 86 which ride in tracks 114 and 218 on beam flanges 192
 and 194. Head 85, which includes tooling, typically a fastener upset tool
 as shown at 219, is moved along the above described b.sup.1 -axis path by
 the following arrangement. Bearings 220 on the head assembly 85 ride along
 curvilinear ways or tracks 222 on carriage side walls 206, 208. The fixed
 curved rails 222 and traveling bearings 220 comprise a curvilinear bearing
 set commercially available from THK. A ball screw drive 224 including a
 servo motor on carriage 86 operates a nut 226 mounted on head 85. The
 b.sup.1 -axis movement of head assembly 85 likewise is in the neighborhood
 of 18 degrees, and is programmable or under closed loop normality sensor
 control. Fastener upset tool 218 is moved toward and away from the
 workpiece in a known manner by suitable motive means 221 which can be
 hydraulic or the aforementioned electric roller screw actuator of U.S.
 Pat. No. 5,829,115.
 The machine control 230, shown in FIGS. 7A, 23, and 24 is in communication
 with the above described drive components and various encoders and sensors
 to provide computer controlled guidance to accomplish the controlled
 movement of the above described components. The result is that machine
 control 230 moves the components of the positioning tooling apparatus 10
 in a controlled manner so that the carriages 84 and 86 and their
 associated head 83, and 85 containing tooling travel over the entire
 portion of the surface of workpiece 12 in which fasteners are to be
 installed. Such computerized control is known to those skilled in the art.
 The apparatus 10 for positioning tooling according to the present invention
 operates in the following manner. The gantry beam assembly 70 is shown in
 an initial or setup position in FIGS. 3 and 7. In this position, the first
 and second beams 72 and 74 and the carriages 84, 86 carried thereby are
 disposed in planes substantially parallel to the planes including the
 floor or supporting surface 20 and the tracks 32,34 and rails 36, 38. As
 seen in FIG. 7, the entire gantry beam assembly 70 including carriages 84,
 86 are below the upper surface of the fixture base 18. While the gantry
 assembly 70 is in the setup position the workpiece can be installed in
 fixture 14 without any interference by the gantry assembly 70. The setup
 position also enables the cassettes 164 to be replenished with fasteners.
 The gantry pedestals 30 and 50, gantry beam assembly 70 and carriages 84,
 86 co-operate to position the tooling head 83 and 85 at selected and
 controlled locations along and about the workpiece 12 in the following
 manner. Simultaneous movement of pedestals 30 and 50 linearly along the
 Y-axis, in combination with simultaneous movement of carriages or
 elevators 42 and 52 linearly along the W and Z axes to move gantry 70
 relative to supporting surface 20, moves heads 83 and 85 containing
 tooling about the circumference of workpiece 12. Thus, the pivot axis 81
 of gantry beam assembly is moved along a first path parallel to the
 longitudinal axes of pedestals 30 and 50 and along a second path
 substantially perpendicular to these axes. The first path is in the
 direction of the W and Z axes and the second path is in the direction of
 the Y axis. In other words, there is movement of tooling heads 83 and 85
 along a curvilinear path along a plane perpendicular to the longitudinal
 axis of workpiece 12. This is illustrated in FIG. 8.
 In particular, the W and Z axes drive means 44 and 54, respectively, move
 the first and second elevator means or carriages 42 and 52 which, in turn,
 move the gantry assembly 70 carrying heads 83, 85 toward and away from the
 supporting surface 20 along the W-axis and Z-axis, and the first and
 second drive means 44 and 54 move the first and second pedestals 30 and
 50, respectively, along the tracks 32, 34 and rails 36, and 38, that is
 along the Y-axis. Simultaneously, in order to accommodate the curvilinear
 surface of the workpiece, the rotating means 104 and 106 on the first and
 second pivot assemblies 80 and 82, rotate the gantry beam assembly 70
 about the A-axis, such that the heads 83 and 85 do not contact the
 workpiece 12 during the foregoing positioning movement. Thus, gantry beam
 assembly 70 is rotated or pivoted about axis 81.
 When the first and second head assemblies 83 and 85 are at the location
 where an operation is to be performed on the workpiece 12, such as
 drilling, fastener insertion and upset, the drives 180 and 224 operate to
 move head assemblies 83 and 85, respectively, to accomplish rotation about
 the b.sup.1 -axis, which results in normalization of the tools with the
 point on the surface of the workpiece 12 where the operation is performed.
 Additional normalization is provided by the movement of heads 83, 85 about
 the A-axis as previously described. The tools on head 83 are indexed into
 position and the tools on both heads are moved toward and away from
 workpiece 12 by the motive means 166 and 221, all in a known manner.
 The first and second head means 84 and 86 are also moved along the X-axis
 so as to be positioned at any other point on the surface of workpiece 12.
 Further, if the workpiece 12 has a complex curvature, elevator means or
 carriage and the associated slip joint means communicating with the
 pedestal may be actuated, while the other elevator means or carriage on
 the other pedestal is not moved to accommodate such complex workpiece
 structure, as shown, for example, in FIG. 18.
 In a typical fastener installation operation on a workpiece like that shown
 herein, a first pass of the tooling is made along a path about the
 circumference of workpiece 12 with fasteners being installed at spaced
 locations along that path. Then the apparatus is indexed in the X
 direction whereupon a second pass of the tooling is made to install
 fasteners at spaced locations along a second circumferential path. This is
 repeated successively along the X-axis along the entire length of the
 workpiece 12. Additionally, the first pass of tooling may be made along
 the longitudinal path of the workpiece, that is indexed along the X-axis
 to each location where tooling is to be performed on the workpiece. The
 second pass may of tooling may then be made along the longitudinal axis of
 the workpiece, that is along the X-axis, but at a different point on the
 circumference of the workpiece.
 All of the above described movement and positioning may be controlled by
 control means 230. Hence, the apparatus 10 for positioning tooling is
 capable of accommodating and performing positioning tooling on a variety
 of differently shaped workpieces. In particular, the apparatus 10 features
 flexibility in application toward various fuselage body sections utilizing
 Z-axis and W-axis travel to accommodate different diameters and an
 adaptive workline to maintain normality of the drill/riveting head to the
 fuselage skin. The apparatus 10 is usable on uniform as well as tapered
 fuselage sections. Typical operations include riveting the fuselage
 section to stringers, riveting seams on the fuselage panels and localized
 riveting of clips, frames, window belt sections and similar components.
 FIGS. 19-24 illustrated apparatus according to another embodiment of the
 present invention wherein the gantry beam assembly includes one beam which
 carries a first head containing tooling for movement relative to one
 surface of a workpiece. A second head containing tooling is move relative
 to the workpiece by means physically independent of the gantry. Referring
 first to FIG. 19 a workpiece 250 of compound curvature, for example a
 portion of the front end of an airplane fuselage, is supported by a
 fixture 252 which rests on a supporting surface 254. A pair of gantry
 pedestals 256 and 258 are supported on carriages 260 and 262 for movement
 along the Y axis in a manner similar to pedestals 30, 50 and carriages 28,
 48 in the embodiment of FIGS. 1-18. A single gantry beam 270 is located
 between pedestals 256, 258 in a manner similar to the gantry beam assembly
 70 of FIGS. 1-18. Gantry beam 270 is connected through shaft assemblies
 274 and 276 at opposite ends thereof to controlled rotating means 278 and
 280, respectively, which in turn are supported by first and second
 elevator means 282 and 284, respectively, on pedestals 256 and 258. Thus,
 the single gantry beam 270 is rotated about the A axis in a manner similar
 to that of beam assembly 70 in the embodiment of FIGS. 1-18. One of the
 pivot assemblies, in the present illustration the one associated with
 shaft assembly 276, may be provided with a slip joint mechanism to allow
 tilting of gantry beam 270 as shown, for example, in the broken line
 representation in FIG. 19. Thus, the foregoing movements of gantry beam
 270 are substantially similar to those of gantry beams assembly 70 in
 FIGS. 1-18. In this embodiment, the pivot assemblies include
 gimbal/spherical bearing mechanisms, represented at 296 and 298 in FIG.
 20, to allow the foregoing tilting and to allow additional movements of
 gantry beam 270 such as at an angle to the X axis as shown, for example,
 in the broken line representation in FIG. 19. This and other additional
 degrees of movement of gantry beam 270 enables a head 300 carried thereby
 to reach all portions of the compound curved surface of workpiece 250.
 Head 300 in this embodiment carries tooling similar to that carried by
 head 83 in FIGS. 1-18. Head 300 also is movable about the b.sup.1 axis in
 a manner similar to that of head 83. This together with the movements
 allowed by the gimbals avoids extreme tilting of beam 270 to reach all
 portions of the workpiece surface.
 FIGS. 22-24 illustrate one form of arrangement for moving another head
 along the opposite surface of workpiece 250 and which is physically
 independent of the gantry. Gantry beam 270, head 300 and pedestals 256,
 258 are omitted from FIGS. 22-24 for simplicity of illustration. Head 310
 is supported at the upper end of a telescoping arm assembly 312 the lower
 end of which is mounted on a carriage assembly 314. Assembly 314 includes
 a first carriage 316 movable in a first direction which is parallel to the
 longitudinal axis of workpiece 250 and a second carriage 318 movable on
 carriage 316 in a direction substantially perpendicular to the first
 direction. Carriage 316 is driven along tracks 320, 322 by suitable
 controlled means in a manner similar to that of either carriage 28 or 48
 in FIGS. 1-18. Likewise, carriage 318 is driven along tracks 324, 326 on
 carriage 316 by suitable controlled drive means. Carriage 316 travels in
 the direction indicated by arrow 330 in FIGS. 22 and 23 which is parallel
 to the longitudinal axis 332 of workpiece 250. Carriage 318 tracks in the
 direction of arrow 334 in FIGS. 23 and 24.
 Raising and lowering of telescoping arm 312 in the direction of arrow 340
 in FIG. 24 in conjunction with movement of carriage 318 in the direction
 of arrow 334 moves head 310 along the curvature of the inner surface of
 workpiece 250. This path of movement of head 310 is shown by arrows 346
 and 348 in FIG. 24. Head 310 is mounted on the end of arm 312 for b axis
 movement as shown in FIG. 23, thus being about an axis substantially
 perpendicular to the longitudinal axis of workpiece 250. FIG. 23 shows
 head 310 in two different locations and orientation during use. Arm 312 is
 rotatable about its longitudinal axis indicated by arrow 354 in FIG. 24.
 This can be accomplished, for example, by a gear 360 mounted on the lower
 end of arm 312 and rotated by a pinion operated by controlled drive means
 362. A more detailed description of a similar telescoping arm assembly may
 be found in U.S. Pat. No. 5,477,597 issued Dec. 26, 1995 entitled
 "Apparatus For Positioning Tooling", the disclosure of which is hereby
 incorporated by reference. Head 310 carries a fastener upset tool similar
 to head 85 in FIGS. 1-18. The various movements of the arrangement of
 FIGS. 22-24 associated with head 310 and the gantry arrangement of FIGS.
 19-21 associated with head 300 are controlled by the system control.
 The apparatus of both embodiments of the present invention operates to
 install fasteners of various types including rivets, slugs, bolts, Hi-Lok
 fasteners, Huck-type fasteners, Shure-Lock type fasteners and other. The
 apparatus of both embodiments of the present invention operates on
 workpieces of a variety of materials including aluminum, titanium, fiber
 glass, aluminum honeycomb, carbon-graphite-epoxy, Kevlar and others.
 It being understood that various changes in the details, materials, steps
 and arrangement of parts, which have been herein described and illustrated
 in order to describe the nature of the invention, may be made by those
 skilled in the art within the principle and scope of the present
 invention.