DETAILED DESCRIPTION

[0040] Attention is directed to FIG. 1 , which shows a robotic device 10 that can be employed to provide a working operation on a workpiece surface. A suitable workpiece surface may be any one of a variety of planer or non-planer surfaces, such as the exterior surface 11 of aircraft 12 (see FIGS. 7 and 8 ), or surfaces (including windows) of buildings (see window surface 13 in FIG. 9 ), or other similar surfaces of ships, storage tanks, buildings, bridges, trains, pipelines, billboards or the like. The substrate comprising surface 12 may be metallic such as aluminum, steel, or non-metallic, such as plywood or other wood, concrete, wallboard, stucco, or other materials wherein a vacuum seal can be effected in the manner further described herein. Robotic device 10 includes a base 14 having a bottom side 16 and an upper side 18 (see FIG. 2 ). A plurality of vacuum cups 20 are provided affixed to the bottom side 16 of base 14 . In the embodiment illustrated in FIG. 1 , and as further detailed in FIG. 6, a mounting ring 22 is used to compress an upper mounting ring portion 24 of the vacuum cup 20 against the bottom side 16 of base 14 . Suitable fasteners 26 or another structure or chemical compound that can accomplish the same result can be used to sealingly affix the vacuum cup 20 to the bottom side 16 of base 14 , generally in the manner as shown in FIG. 6 . In the embodiment shown in FIG. 6 , each of the vacuum cups 20 includes (a) a low friction foot 30 of unique design further described below, and (b) a resilient, flexible, compressible and expandable sidewall 32 of sufficient strength and durability to withstand vacuum use and constant flexing during robotic operations. As illustrated in FIG. 6 , the vacuum cup sidewall 32 may include two or more V-flex, accordion pleat shaped corrugations 34 . An outlet port 40 is provided with a seal 42 (such as in the shape of a circular 0 -ring). The seal 42 is adapted for seating and sealing against a sealing surface 43 of the fluid limiting flapper valve 44 . The flapper valve 44 is located in fluid communication with the outlet port 40 , and adjacent to seal 42 , by being positioned below the inlet portion 46 of the outlet port 40 . The fluid limiting valve 44 is biased toward an open position, but is designed to be responsive to pressure of an escaping airstream against the front side 47 of valve 44 . In this manner, the fluid limiting flapper valve 44 is responsive to at least partially close off air flow through the outlet port 40 . For example, when valve 44 is open, a large flow of fluid can escape by following the outlet path indicated by reference arrow 48 . However, when valve 44 closes and sealing surface 43 is mates with seal 42 , only a minimum of fluid escapes, via the path shown by reference arrow 50 . As seen in both FIGS. 6 and 11 , when valve 44 is closed, fluid as indicated by reference arrow 50 escapes only through a small passageway 52 defined by edgewalls 54 in fluid limiting valve 44 . As depicted in FIG. 6 , this situation occurs, for example when the foot 30 of vacuum cup 20 encounters a discontinuity 56 in a surface 12 being inspected, so that a large volume of fluid passes in the direction of reference arrow 58 from ambient conditions to the interior, fluid containing portion 60 of vacuum cup 20 . In such situations, the minimum flow outlet passageway 52 is sized and shaped to allow a preselected fluid flow volume out of the passageway 52 , when the fluid limiting valve 44 is in the closed, vacuum loss position. This is useful since vacuum capability (i.e., the quantity of air which can be extracted by the vacuum pump) is not unnecessarily used up in the event of vacuum loss at one, or in the event of vacuum loss at even a number of vacuum cups.

[0041] By way of further explanation, the outlet 46 has an outlet seal 42 , and the fluid limiting valve 44 has a seal portion 43 that sealingly seats against the outlet seal 43 . The fluid limiting valve 44 is thus responsive to fluid flow to move between (a) a normal flow, open position, wherein said valve 44 allows fluid flow unimpeded through the outlet 46 , and (b) a vacuum loss, closed position, wherein high flow toward the outlet valve 44 closes the valve 44 so that the seal portion 43 of the fluid limiting valve 44 sealingly seats against the outlet seal 42 , until a normal vacuum condition resulting in a low fluid flow situation is restored to the vacuum cup 20 . It has been found advantageous to provide a reed type valve for the fluid limiting valve 44 , with the valve biased toward a normally open position, such as by a spring (here, spring 62 inherent in the construction of the attachment end 64 of valve 44 ) of suitable spring force. In one embodiment, clearance in the open position of about {fraction (1/10)} inch between seat 42 and sealing surface 43 is sufficient, at the outward end 66 of valve 44 .

[0042] Returning now to FIG. 1 , in this embodiment, at least three points of support are provided for the base 14 of the robotic device 10 . As illustrated in FIG. 1 , the three points of support are (a) a pivotable surface 70 (here shown provided by a pivoting wheel 72 ), (b) first primary traction drive surface 74 (here provided by first drive wheel 76 ) and (c) second primary traction drive surface 78 (here provided by second drive wheel 80 ). These three surfaces just described provide three points of support that are affixed to base 14 and which are adapted to limit the distance of the base 14 relative to the workpiece surface 12 being traversed, so as to limit the working compression range R, i.e., the amount of downward compression available for vacuum cups 20 (such as accommodated by the V-shaped compression portions 34 in the design illustrated in FIG. 6 ) between the bottom side 16 of the base 14 and the surface 12 being traversed. On hypothetical maximum working compression range distance D is indicated in FIG. 6 , where a foot 30 ′ is shown in phantom lines in fully compressed position. This three point support configuration allows the robotic device 10 to function on curved surfaces 12 as if supported by a three legged stool, which of course, can evenly and securely support a structure above an uneven or compound curved surface while all three points are in contact with the workpiece surface 12 .

[0043] For added drive traction, and support it has been found it appropriate in some embodiments to provide a secondary traction surface for each of the primary traction surfaces. As shown, a first secondary traction surface 82 is provided to move in concert with the first primary traction surface 74 . The first secondary traction surface 82 is, as shown in FIG. 1 , provided by a wheel 84 . Similarly, a second secondary traction surface 86 is provided to move in concert with the second primary traction surface 78 . As shown the second secondary traction surface 86 is provided by a wheel 88 .

[0044] The pivotable contact point 70 , located adjacent the normal front 90 of frame 14 , allows the robotic device 10 to turn when the device 10 is traveling along a direction of travel such as indicated by reference arrow 92 in FIG. 1 .

[0045] Turning now to FIGS. 2 and 3 , tubular frame portions 100 , 102 , 104 , and 106 can be provided for both structural support as well as to provide a vacuum header 108 to connect vacuum inlet legs 110 , 112 , 114 , and 116 to vacuum outlet 118 . Each of the just mentioned vacuum inlets and frame portions also provide a structural frame suitable for attachment of eye-bolts 120 , which provide attachment points for safety lines 122 (see FIG. 2 ) and/or umbilical lines 123 (see FIG. 7 ). Thus, the frame, 124 , made up of the just mentioned tubular frame portions and the just mentioned vacuum inlets, provides both a structural and a fluid communication function. Note that as can be further appreciated from FIGS. 6 and 7 , the base 14 has a plurality of vacuum apertures 130 therethrough (further defined by outlet ports 40 ), and that those vacuum apertures 130 are in fluid communication with the vacuum header 108 .

[0046] Returning now to FIG. 2 , additional details of one embodiment of suitable drive components is provided to enable one of ordinary skill in the art to make and use the novel robotic device described herein. As earlier noted, in one embodiment, it has been shown that wheels may be used in certain applications as traction devices to self propel the robotic device 10 across a workpiece surface 12 . When utilizing wheels on a robotic device, it has been found advantageous to utilize a lightweight rim 120 , such as magnesium or aluminum, with a resilient urethane wheel 122 composition. Ideally, soft wheel compounds are used for maximizing traction. It has been found that such a soft urethane composition having a 30 Shore A durometer is advantageous. For driving the wheels, endless belts 140 and 142 are connected to a drive motors 144 and 146 . As illustrated, the endless belts 140 and 142 are provided in the form of a linked chain, and resultantly, drive sprockets 148 and 150 are used at motors 144 and 146 , respectively. Idler sprockets 152 and 154 are used at wheels 76 and 80 . Idler sprockets 153 and 155 are used at wheels 88 and 84 . While I have found it useful to provide the various sprockets in a high molecular weight polyethylene, any suitable substance having the desired strength, stress resistance, and weight characteristics may be utilized.

[0047] Attention is directed to FIGS. 16, 17 , and 18 , where further details of wheels and drive components are illustrated. In the embodiment illustrated in the just mentioned figures, a pair of driven wheels, for example, wheels 80 and 88 , are rotatably affixed to pivotable truck 160 with wheel axles 162 and 164 , respectively, located at wheel axle retaining apertures 163 and 165 , respectively. A truck axle retainer defined by truck axle retainer edgewall 168 serves to pivotably receive truck axle 170 therein. In one embodiment, truck axle 170 is provided as a unitary circular rod (see the cross-section illustrated in FIG. 18 ) with swaged first 172 and second 174 ends each having therein a fastener receiving aperture, 176 and 177 , respectively for receiving fasteners 178 and 180 therethrough. If threaded fasteners are utilized, nuts 182 are affixed to fasteners 178 and 180 to secure truck axle 170 to base 14 . A normally rectangular shaped drive accommodating cutout, defined by drive unit wall 184 , is cut through base 14 . Motor 146 is affixed during operation to a suitable motor mount plate portion 185 of truck 160 , such as by fasteners 186 . Consequently, although at the centerline 188 of the truck, no up or down motion of the truck occurs with respect to the reference plane of the base 14 , the wheels are allowed to move up and down, with motion up as indicated by reference arrow M _U in FIG. 16 , and motion down as indicated by reference arrow M _D in FIG. 16 . A maximum movement of the wheels may be allowed, indicated as M _U-MAX , and M _D-MAX , respectively. With respect to discussion at other parts of this disclosure, however, it must be noted that a robotic device acts as if the point of contact of the wheels is at a single point 190 on workpiece surface 194 that is directly below the truck axle 170 (i.e., normally perpendicular to the longitudinal axis 196 of the truck). Thus, a “three point” contact system is maintained, with one point of contact effectively at a point 190 beneath each one of the trucks 160 , and with one point of contact at the pivoting wheel 72 . As a result, like a three legged stool, robot 10 can easily traverse curved workpiece surfaces while maintaining three points of contact with the workpiece surface. The “three effective points of contact” configuration is further reinforced in FIG. 1 , where the reference arrows I, J, and K are noted as force vectors about which contact force of robot 10 with a workpiece surface is disposed. Reference arrows J and K are of course equivalent to the reference arrow 192 discussed in connection with the truck 160 described and shown in FIG. 16 .

[0048] Motors 144 and 146 are mounted on a motor platform 185 . That platform is often a rectangular platform integrally formed along one edge with truck 160 , but can also be separately formed and attached thereto. In one embodiment, the drive motors 144 and 146 are provided in the form of direct current electrical motors, and more usually (but not necessarily) in the form of 24 volt DC electrical motors. More specifically, use of a pittman type DC motor with encoder, utilizing a 187:1 gear reduction, has been found advantageous. Each one of the at least two drive motors is connected to drive one or more of said the at least two drive wheels of the robotic device 10 . Alternately, pneumatic (air driven) or hydraulic (liquid driven ) motors may be utilized for various applications as appropriate, especially where it simplifies the number of utility lines provided for a specific end effector application. Drive motors 144 and 146 , regardless of motive force, are in one embodiment completely independent, so that the robot 10 is maneuverable via differential speed between drive motors 144 and 146 , or by completely separate drive action of each motor, separate from the other(s) of the drive motors.

[0049] As seen in FIG. 1, a mount 200 is provided for mounting a preselected inspection tool or working tool, such as a sander 202 (shown here in FIG. 1 ), or such as an eddy current testing device (as illustrated in FIGS. 2, 3 , and 4 ). Many other devices, such as magnetic, laser or other optical unit, video, or other inspection or working devices, some of which have been mentioned above, can be carried by a suitably sized robotic device configured in accord with the disclosures herein. For example, in the device shown in FIGS. 1, 2 , 3 , and 4 , a small robotic device 10 having a weight of about 9 pounds can carry an working tool or an inspection tool via vacuum adhering means described herein along a surface 12 to be inspected. However, larger units configured in the same manner can carry payloads of up to 70 pounds, or more. As illustrated in FIG. 1, a typically suitable sander would be a Dynabrade brand orbital sander, Model 57810, such as is available from Dynabrade Industrial Power Tools of Clearance, N.Y. (http://www.dynabrade.com). The model 57810 has a weight of 2.75 pounds (1.25 kg) and utilizes compressed air at 2 cubic feet per minute (368 LPM) at 90 psig (6.2 Bars) with a pad size of 3-⅔ inches width by 7 inches long.

[0050] To appreciate the capability of the robotic device shown herein, note that to slide the robotic device 10 while all six vacuum cups 20 are operating with about 3 inches of mercury vacuum, takes about 500 inch-ounces of force, when the combined weight of the robotic device 10 and the tool 202 is about 18 pounds. In the configuration illustrated, about 30 pounds force are developed by each vacuum cup 20 when the cups are operating at the aforesaid 3 inches of mercury vacuum. It must be further considered by the reader that the robotic device 10 disclosed and described herein does not move via “stepping”, i.e., sequential positioning, and then repositioning, of the vacuum cups 20 . Rather, the foot 30 of each of the vacuum cups 20 slides over the workpiece surface 12 being inspected or worked, while, at the same time, a sufficient number of vacuum cups 20 maintain vacuum so as to adhere the robotic device 10 to the workpiece surface 12 .

[0051] Turning now to FIG. 8 , with the embodiment shown herein, vacuum cup pairs 230 , 232 , and 234 are shown. While utilizing any two of the three pair 230 , 232 , and 234 vacuum cups 20 , a working radius R as small as two foot can be negotiated by a suitable sized robotic device 10 . For example, robotic device 10 _A is shown starting to negotiate an outside radius, and the front pair 234 of vacuum cups has lost effective contact with surface 12 . However, by the time the device reaches the position illustrated by robotic device 10 _B , the front pair 234 and the center pair 232 of vacuum cups are effective, although the rear pair 230 of vacuum cups 20 have now lost effectiveness. And, it should be understood that although pairs of vacuum cups have been utilized for purposes of illustration, the method taught herein is not considered limited to merely “pairs”, but should be thought of as a method for providing plurality of cooperating vacuum cups, i.e., a set, however so many as might be suitable for general purposes or for a specific or specialized purpose.

[0052] Attention is directed to FIGS. 6, 14 , and 15 , where further details of the unique vacuum cups 20 are noted. To form the unique vacuum cups 20 , 1 have found it advantageous to provide a thin Teflon sheet 30 , normally of about 0.005 inch, or more, into a first mold 240 in the desired vacuum cup shape (normally an annular shape with a generally C-shaped lower contact face 242 . A complementary second mold 244 is provided to clamp the Teflon sheet 30 into the desired generally upwardly opening C-shaped foot configuration. With the first, external 240 and second, internal 244 molds in place, the Teflon sheet 30 is baked at about 375 degrees F. for about 2 hours, or until the Teflon absorbs and retains the desired shape when cooled to ambient temperature. Then, as indicated in FIG. 15, a third, complementary mold 246 is utilized and thereunto is poured a desirable resilient compound 248 to bond directly to the preformed Teflon foot portion 30 . I prefer to use an air cure polyurethane (after vacuum bubble removal—degas at 29 inches mercury vacuum for at least 10 minutes), which sets up after at least 12 hours, and more preferably 24 hours, and which ideally is allowed to cure for at least 48 hours, and which hardens into about a 50 Shore A durometer polyurethane rubber. As shown in FIG. 6, I have found it advantageous to provide at least ¼ inch thickness (see reference letter A in FIG. 6 ) of polyurethane backing above the 0.005 inch (see reference letter B in FIG. 6 ) of non-stick, preferably Teflon portion of the vacuum cup 20 foot, with a width W of at least about one inch. And, while I have found it advantageous to utilize a pair of V-shaped compressible portions 34 , more or less than two such portions are equally capable of serving in the functional capabilities required, to provide the compression range distance D as above described. What is necessary is that a suitable accordion pleat bellows shape is configured in a flexible elastomer in which the vacuum cup 20 is shaped, and that a low-stiction surface 250 is provided for a vacuum cup foot.

[0053] FIG. 7 illustrates a robotic device 10 as utilized for nondestructive inspection of an aircraft 300 . For laser control, a retro-reflector or cat's eye 302 is mounted on the robot device 10 as the device rides on the surface 12 of aircraft 300 . In the non-destructive inspection system, one or more robots 10 are mounted to travel across the surface 12 of the aircraft 300 . In practice, for example, three different robots 10 can be utilized along with six laser tracking units 304 when inspecting a large commercial aircraft. As shown in FIG. 7, a movable carriage 306 is associated with each robot 10 and includes, or is further connected to a remote vacuum pump, which in any event is connected by a suitable conduit in umbilical 122 to the vacuum manifold outlet 132 on the robot 10 . In addition, electrical feed lines 260 and 262 are connected between the carriage 306 and the robot 10 . As illustrated in FIG. 7 , one of the carriages 306 is mounted to travel on an overhead track 310 and is connected to a robot 10 which is adapted to move across the upper surfaces of the aircraft 300 , while a second carriage 306 travels on the ground and is operably connected to a second robot 10 that traverses the lower surfaces of the aircraft 300 .

[0054] In carrying out the non-destructive inspection, the vacuum system is initially started to create a vacuum in the vacuum cups 20 and enable the robotic device 10 to adhere to the surface 12 of the aircraft 300 . The aircraft 300 has certain tooling locations, or depressions, located at various positions and which are used as reference points to take dimensions during the manufacture and set-up of the aircraft. These depressed reference points are generally referred to as fiducials F. Through a suitable control interface, drive motors 144 and 146 on the robot 10 are then actuated to move the robot 10 over the aircraft surface 12 until the sensor 302 is engaged with a fiducial F. Through the computer control and location system, this is established as an origin point. As a large aircraft generally has a number of fiducials F ₁ , F ₂ , etc, so the robot 10 is moved and engaged with each fiducial F to obtain a series of origin points.

[0055] The desired operating program is selected in the computer, then actuates the program to operate the motors 144 and 146 to move the robot 10 in the desired path of travel on the aircraft 300 surface 12 . Usually, at time of the first pass inspection, the interior of the aircraft 300 is under atmospheric pressure. As the robot 10 moves across the aircraft surface the sensor 302 will ride above the surface as carried by the base of the robot 10 . For example, as described in the tracking system of U.S. Pat. No. 4,714,339, the disclosure of which is incorporated herein by this reference, a laser beam is directed from tracking unit 304 to the target, which is the retro-reflector 302 mounted on robot 10 , and the retro-reflector 302 reflects a beam back to a tracking unit 304 . Photosensors attached to the tracking unit 304 provide error signals to a servo system, which controls optics at the tracking unit to provide the direction necessary to accomplish the coincidence of the beams. The separation of the incident or source beam and the reflected beam are measured and by measuring the direction of the beams relative to the tracking unit or tracking point, the target can be located in spatial coordinates and the orientation of the retro-reflector 302 can be continuously determined, thus providing a surface map of the aircraft 300 . Similar mapping can also be achieved by use of suitable infrared tracking systems, using a suitable X-Y-Z coordinate photosensor system.

[0056] After the surface mapping of the entire aircraft 300 has been completed, the interior of the aircraft is usually then pressurized at about 1 atmosphere of pressure, and the surface mapping operation is repeated. If any portion of the aircraft surface 12 shows a deviation under pressurized conditions beyond a given tolerance it can indicate a potential defect in the surface, such as a crack or faulty fastener. Any potential defective area can then be manually inspected.

[0057] By using the robot 10 in conjunction with a suitable tracking system, surface mapping of the aircraft 300 can be accomplished to determine potential areas of defect without the necessity of stripping paint from the aircraft surface and without the need of a manual inspection of the entire aircraft surface. As the paint stripping, manual inspection, repainting and waxing operations are eliminated, the overall time and cost for the inspection is greatly reduced.

[0058] With respect to operations such as washing, waxing, sanding, etc. it may be advantageous to incorporate, in combination, a suitable working tool and a vacuum cup 20 as above described, as further depicted in FIG. 11 . Here, a vacuum cup 20 has a centrally mounted shaft 320 driven sander 322 having a rotating body 324 , a resilient tool mounting pad 324 , and a sandpaper or other abrasive surface 326 to act on the surface 330 of a workpiece 332 . An exemplary rotary sander, such as depicted in FIG. 13 , is driven by compressed air 340 , often at 90 psig (more or less), which can be supplied by hose 342 to the head 344 of sander 322 for turning air driven turbine 346 . After turning the shaft 320 , the air is usually exhausted to an air exhaust outlet 348 . Incorporating of the sander into the vacuum cup 20 is advantageous since particulates 350 which are generated by the sanding operation are advantageously swept outward in the direction of reference arrows 352 , and ultimately are swept toward vacuum source 360 , usually for separation at or near a vacuum pump located at the vacuum source 360 . A suitable random orbital sander as depicted in FIG. 13 would be a Dynabrade brand sander, Model 58215, such as is available from Dynabrade Industrial Power Tools of Clearance, N.Y. (http://www.dynabrade.com). The model 58215 has a weight of 1.9 pounds and utilizes compressed air at 2 cubic feet per minute (368 LPM) at 90 psig (6.2 Bars) with a pad size of 5 inches diameter.

[0059] A perspective view of one embodiment for a vacuum cup 20 mounted sander 322 is shown in FIG. 10 . In FIG. 10, a vacuum cup 20 is shown with a rotating body 324 . Here, the further use of low friction stops 366 is illustrated, as suitable for spacing a brush (as set forth in FIG. 12 ) from a workpiece substrate, is shown. In such a case, mounting ring 22 can be provided with additional stop mount receivers 368 , so that threaded stops 366 can be mounted in stop mount receivers 368 , and adjusted to an appropriate height H to limit the working compressive range of the vacuum cup 30 .

[0060] As further identified in FIG. 12 , the resilient tool mounting pad 324 can also be advantageously utilized for mounting of a brush 362 , useful for washing, waxing, polishing, buffing, painting, or like operations.

[0061] In yet another embodiment as illustrated in FIG. 9 , robot 368 is driven by first 370 and second 372 endless belt tracks are spaced between forward idler sprockets 374 and rearward idler sprockets 376 . Tracked belt 370 is driven by drive sprocket 380 , which is energized by drive motor 382 . Similarly, belt 372 is driven by drive sprocket 384 which is energized by drive motor 386 . Drive motors 382 and 386 , as well as other tool or inspection functions, are controlled by a remote control unit 390 . Here, robot 368 is adhering to window 13 . The robot 368 is carrying a squeegee 392 for cleaning window 13 . Washing brushes can be provided for robot 368 in the manner just described and shown in FIGS. 10 and 12 , or another suitable arrangement. Robot 368 can be provided in a manner to adhere to window 13 by a suitable number of vacuum cups 20 (shown in hidden lines), such as 3 or more, which as a minimum quantity should be sufficient in most applications to assure that robot 368 can traverse discontinuities and maintain its moving adherent capability on a selected workpiece. However, the use of 3 pairs might be more conservative, similar to the designs shown for other embodiments illustrated herein.

[0062] It is to be appreciated that various aspects and embodiments of the compact robot designs described herein are an important improvement in the state of the art of tool carrying robotic devises. Although only a few exemplary embodiments have been described in detail, various details are sufficiently set forth in the drawings and in the specification provided herein to enable one of ordinary skill in the art to make and use the invention(s), which need not be further described by additional writing in this detailed description. Importantly, the aspects and embodiments described and claimed herein may be modified from those shown without materially departing from the novel teachings and advantages provided by this invention, and may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. Therefore, the embodiments presented herein are to be considered in all respects as illustrative and not restrictive. As such, this disclosure is intended to cover the structures described herein and not only structural equivalents thereof, but also equivalent structures. Numerous modifications and variations are possible in light of the above teachings. It is therefore to be understood that within the scope of the appended claims, the invention(s) may be practiced otherwise than as specifically described herein. Thus, the scope of the invention(s), as set forth in the appended claims, and as indicated by the drawing and by the foregoing description, is intended to include variations from the embodiments provided which are nevertheless described by the broad interpretation and range properly afforded to the plain meaning of the claims set forth below.