ROBOTIC APPARATUS

ROBOTIC APPARATUS

Background of the Invention Robotic devices have been proposed for per¬ forming a working operation, εuch as cleaning or polish- ing surfaces, that are not accessible to normal manual operations. In general, the robotic devices have been used on flat or planer surfaces such as windows, building panels and the like. The typical robotic device includes- a pair of endless belts or tracks, each carrying a series of vacuum cups. The belts are independently and remotely driven to move the device across the surface to be treat¬ ed, and a source of vacuum, such as a vacuum pump, is connected to the vacuum cups to create a negative pres¬ sure within the cups so that the cups can grip the sur- face and enable the robotic device to move over inclined or vertical surfaces. A typical robotic device can oper¬ ate on smooth continuous surfaces but if the device moves across an obstruction or crack in a vertical or inclined surface, the vacuum may be lost, resulting in the device falling.from the surface.

Large commercial aircraft are normally washed and waxed every thirty days. Because of the large size and shape of the aircraft it is customary to erect a scaffold along side the aircraft and a number of workers supported on the scaffold then hand scrub the outer surface of the aircraft. After scrubbing, the aircraft is waxed and polished using manual rotary buffers. The buffers are relatively heavy and due to the large surface area of the aircraft a buffing operation is a tedious and time consuming operation. The entire operation of scrub¬ bing, waxing and buffing the aircraft usually takes a period of 20 to 30 hours utilizing 10 workers.

Commercial aircraft are also subjected to a non-destructive inspection after 7,000 cycles of pressur- ization. Each take-off and landing in which the aircraft is pressurized is considered to be a pressurization cycle. In the typical non-destructive inspection, the paint is stripped entirely from the aircraft and the seams and rivets are manually inspected. If a defect is observed during the inspection, the area of the defect is marked and is subjected to an eddy-current sensor to determine the magnitude of the defect. After the manual inspection the aircraft is repainted and subsequently waxed and buffed.

The normal paint stripping, inspecting, re¬ painting and waxing operation is extremely time-consuming and labor intensive, resulting in a substantial expend¬ iture. As a further problem the paint stripping operation presents a serious environmental problem, in that methylene chloride is generally used as the solvent to remove the paint and for a large aircraft, such as a Boeing 747, upwards of 1,000 gallons of methylene chlo¬ ride may be required to strip the paint from the air¬ craft. As methylene chloride is toxic and presents an environmental problem, pollution abatement equipment is necessary in order to remove the solvent fumes from the paint stripping area.

Summary of the Invention The invention is directed to a robotic device for performing a working operation on a surface and has particular application to performing a working operation on a contoured surface having surface irregularities such as encountered in a commercial aircraft.

The robotic device comprises a supporting structure or frame which supports an outer open bottom housing or hood. A pair of flexible tracks are mounted on the frame and an endless member, such as a link chain, is mounted for travel on each of the tracks. Each chain in independently driven by a separate motor which is mounted on the frame.

Each of the tracks is formed with at least two channels with each channel having an open side facing the respective chain. A series of vacuum cups are mounted on each chain and a series of first ports are connected between a firεt of the channels of each track and a first group of vacuum cups, while a second series of ports provide communication between a second channel of each track and a second group of vacuum cups. The first and second groups of vacuum cups are preferably in alternat¬ ing sequence.

Negative pressure or a vacuum is applied to each channel and hence through the port to the vacuum cupε, thus enabling the cups to grip a εurface to be traversed.

In a preferred form of the invention, each track is formed with two pair of εide-by-side channels and the vacuum is applied independently to all four channels. In this embodiment, a first series of ports in the chain register with the first and third channels, while a second series of ports in the chain register with the second and fourth channels. As the vacuum is applied independently to the εeveral channels, the robotic device can move over gaps or obstructionε in the εurface without loεing -vacuum in all of the vacuum cupε. If for example, the device moveε over a crack cauεing a loεε of vacuum in one of the track channelε, the vacuum will be retained in the remaining channelε to thereby maintain the device in gripping contact with the surface. In a preferred embodiment the robotic device is employed for non-destructive inspection of aircraft using a laser tracking system. In this embodiment one or more laser units are mounted on the ground adjacent the air¬ craft and a retro-reflector or cats-eye is mounted on a support carried by the robotic device. The support is slidable relative to the robotic device and is biased downwardly so that a shoe or sensor carried by the support will ride against the surface of the aircraft. As the robotic device moves in the deεired path of travel over the aircraft εurface, the εensor or shoe rides on the surface, and through the laser tracking syεtem, the εurface of the aircraft iε mapped. The aircraft iε then pressurized and the surface is again mapped and any surface deviations, outside of a given tolerance, indi¬ cate possible defects in the aircraft surface.

The use of the robotic device along with the laser tracking system, to provide non-destructive inspec¬ tion of a aircraft, eliminateε the manual paint εtrip- ping, viεual inεpection, repainting and waxing of the aircraft aε iε normally uεed and therefore εubstantially ^• reduces the overall time and cost of the non-destructive inspection. As a further advantage, the method of the invention eliminates the use of toxic solventε which are normally uεed to strip the paint from the aircraft and correspondingly eliminates the pollution control devices that are necesεary with the use of such solventε. In a εecond embodiment of the invention the robotic device can be employed to move a working imple¬ ment over the aircraft of other εurface. The working implement can be a rotary εcrubber, buffer, paint sprayer, or the like. By utilizing the robotic device to perform- heεe working operation the extensive hand labor normally required to wash, wax and or paint an aircraft or other surface is subεtantially reduced. As a further advantage, a robotic device enables a conεtant applica¬ tion of preεεure to be applied through the implement to the surface thuε providing a more uniform cleaning and poliεhing operation.

The invention alεo can include a safety feature to prevent the robotic device from falling from the surface in the event of failure of the vacuum syεtem. In this regard, a fan is mounted in an opening or aperture in the outer housing and if the magnitude of the vacuum dropε beneath a preselected valve, the fan iε operated to create a negative pressure within the outer housing or hood to prevent the robotic device from falling from the surface.

The robotic device of the invention has the advantage that it is capable of moving over surface deviations, such as obstructionε or gapε without losing vacuum. Moreover the frame iε compoεed of flexible plaεtic material which enableε the robotic device to follow the curved contour of an aircraft or other εurface to be treated.

Other objectε and advantageε will appear during the courεe of the following deεcription.

Description of the Drawings The drawings illustrate the best mode presently contemplated for carrying out the invention.

In the drawings

Fig. 1 is a longitudinal section of the robotic device of the invention;

Fig. 2 is a section taken along line 2-2 of Fig. 1;

Fig. 3 is a section taken along line 3-3 of Fig. 2 and showing the connection of the drive to one of the chains;

Fig. 4 is an enlarged fragmentary longitudinal εection-taken along line 4-4 of Fig. 3 and εhowing the vacuum connection the vacuum cupε;

Fig. 5 iε a bottom view of the track with partε broken away;

Fig. 6 iε an enlarged fragmentary longitudinal section showing the engagement of the chain with a drive sprocket; and

Fig. 7 is a schematic view showing the use of the robotic device along with a laser tracking system in the non-deεtructive inspection of an aircraft. Description of the Illuεtrated Embodiment

Figs. 1-6 show a robotic device 1 that can be employed to provide a working operation on a surface 2. Surface 2 can either be a planer or non-planer surface, such as an aircraft, building, bridge, storage tank, train or the like.

Robotic device 1 includes an outer open bottom housing or hood 3, which is supported by an internal frame 4. Housing 3 is composed of a rectangular side wall 5 and a generally flat upper surface or top 6, having an opening therein which is bordered by a generally curved upwardly extending flange 7. A series of braces 8 extend diametrically across the opening in flange 7 and support a retro-reflector or cats-eye 9 to be uεed in a laser tracking system, as will be hereinafter deεcribed.

Secured to the lower edge of εidewall 5 iε a strip 10 having a downwardly facing groove which receiveε the upper edge of a bruεh εeal 11, aε εhown in Fig. 3. Bruεh εeal 11 includes a plurality of fine, synthetic, flexible bristles formed of a material such as nylon which engage the surface 2 and provide a seal to the εurface.

Frame 4 conεistε of a pair of inverted V-εhape frame memberε 12 which extend tranεversely of the houεing 3 and each frame member 12 includeε an upper flat section 13, which is secured to the under surface 6 of housing 3. In addition, each frame member 12 is provided with a pair of lower, horizontal flanges 14 and each flange 14 is secured to the upper flange 15 of a bracket 16, as best εhown in Fig. 3. With thiε construction there are four bracketε 16 with a pair of the brackets being located along each side of the device.

Each bracket 16 alεo includes a lower flange 17 which extendε outwardly and is secured to the upper surface of a flexible track or guide 18, as seen in Fig. 3. Each track 18 is preferably formed of plastic material and is connected between a pair of the brackets 16. In addition, a pair of braces 19 extend transversely of the device and connect the tracks 18 together.

Tracks 18 serve to guide the lower run of an endless link chain 20 as εhown in Fig. 3. To drive the chainε 20 in their endless paths of travel, a sprocket 21 is mounted for rotation outwardly of each bracket 16 and the sprocketε on each εide of the frame are engaged with the respective chain. Each sprocket 21 is carried by a shaft 22 which extends outwardly from the respective bracket 16, as shown in Fig. 3. The ends of each track, as illuεtrated in Fig. 5, are provided with longitudinal, open-ended slotε 23 which receive the reεpective εprockets 21.

One sprocket of each longitudinal pair iε an idler εprocket, while the other εprocket 21 of each longitudinal pair iε a driven εprocket. To drive the sprockets 21b, an electric motor 24 is located inwardly of the bracket 16 and operates through a gear box 25 with the output shaft of the gear box connected to the shaft 22 of the driven sprocket 21. A separate motor 24 is utilized with each driven sprocket 21. Thus operation of the motors 24 acting through the sprockets 21 will drive the respective chain 20 to move the robotic device in the desired path of travel along the surface 2.

As beεt εeen in Fig. 1 the upper run of each chain 20 is supported on a guide bar 26. A pair of rods 27 extend downwardly from each guide bar 26 and the lower end of one of the rods is connected to the reεpective track 18, while the lower end of the second rod is connected to a manifold block 28, which is mounted on the track 18. Coil springs 29 are located about the rods 27 and urge the guide bar 26 upwardly thereby acting to tenεion the chain 20.

The construction of each link chain 20 is best illustrated in Figs. 3, 5 and 7. Each chain 20 is com¬ posed of a serieε of pivotally interconnected links 30 and a boεε or tubular projection 32 extends outwardly from one side of each link 30 and is received within a flanged recesε 33 in the adjacent link. Pinε 34 provide a pivotal connection between the boεε 32 of one link and the hinged recess 33 of the adjacent link. The hinged bosεeε 32 are adapted to be engaged by notches 35 in the respective sprockets 21, as best seen in Fig. 6. As shown in Fig. 3, the hinged connections 32 of chain 20 are guided for movement within a central groove 38 in track 18 and each chain link iε provided with a pair of outwardly extending ears or flanges 30a which are received within guideways 38a in the track.

The engagement of flanges 30a with guidewayε 38a prevents downward diεplacement of the chain 20 from track 18.

A εerieε or row of vacuum cups 39 are mounted on the outer surface of each chain 20, as shown in Fig. 3. The baεe 40 of each cup 39 iε εecured by screwε 42 to the chain links 30. Each chain link 30 iε provided with a pair of side-by-side holes 43a and 43b, and one of the holes 43a registers with a hole 44 in the base 40 of the vacuum cup 39. Mounted on the upper surface of chain 20, as shown in Fig. 3, is a flexible plastic belt 45. A serieε of tubeε 46 are formed integrally with the belt and pro¬ ject through the aligned holeε 43 and 44 in chain links 30 and vacuum cup 39. as shown in Fig. 3. One group of vacuum cups 39 have holes 44 aligned with holes 43a, while a second group of vacuum cups have holeε 44 aligned with holes 43b. Preferably the two groups of vacuum cups are in alternating sequence. Accordingly, the tubes 46 are staggered and are inserted within the aligned openings 43a and 44, or 43b and 44.

The surface of each track 18 facing chain 20 is formed with four grooves or recesses 47, 48, 49 and 50. As seen in Fig. 5, grooves 47 and 48 are in side-by-εide relation and grooves 49 and 50 are in side-by-εide relation and are εpaced longitudinal from grooveε 47 and 48.

A flexible trough or channel member 51 iε mounted within grooveε 47 and 48, and εimilarly a flexi¬ ble channel member or trough 52 is mounted in grooves 49 and 50. Each channel member 51 and 52 includeε a pair of εide by side channels 53 and the channels 53 of channel member 51 are located within grooves 47 and 48, while the channelε 53 of channel member 52 are located within grooveε 49 and 50. Each channel member 51 and 52 iε pro¬ vided with a flexible peripheral lip 54 which iε engaged with and rideε againεt of belt 45, aε εhown in Fig 3, thuε providing a εeal between the channelε and the belt. The channel memberε 51 and 52 are urged in a direction toward the respective chain 20 by a waffle spring 55 which is located between the central portion of- each channel member and the lower surface of the track 18 aε seen in Fig. 3.

As best illustrated in Fig. 4, a block 56 is formed integrally with the upper εurface of each channel member 51 and 52, and a nipple 57 extendε outwardly from each block. Each nipple iε connected through an internal pasεage in block 56 with the interior of the reεpective channel 53. Tubeε 58 connect nippleε 57 to manifold block 28 which is mounted on the track 18. A εource of negative preεεure or vacuum, εuch as a vacuum pump, is connected through conduit 59 to manifold 28 and through suitable valving in the manifold the negative pressure is applied through tubes 58 to the four channels 53. The negative presεure is then applied from each channel 53 through tube 46 in belt 45 to the corresponding vacuum cups 39. The use of the multiple channels 53, each being individually connected to a εource of vacuum, preventε the entire loεε of vacuum to the robot if the robot εhould traverεe an obstruction, crack or other εurface deviation. For example, if the robot should move longitudinally over an elongated crack with the crack being aligned with the grooves 47 and 48, the vacuum in the channels 53 located in grooves 47 and 48 may be lost, but the vacuum will be retained in the channels 53 located in the grooves 49 and 50, thus preventing the robot from falling from a vertical or inclined εurface. Similarly, if the robot εhould move across a transverεe crack the vacuum may be lost in a pair of side-by-side channels 53, but the other pair of side by side channels will retain the vacuum to maintain the robot in contact with the surface.

In addition, a flexible valve member 60 is connected by screw 60a to the base 40 of each vacuum cup 39 and is in registry with hole 44. Valve member 60 iε contoured εo that it iε normally open, as shown in Fig. 3 to permit vacuum to be drawn in cup 39. However, if cup 39 should travel over a crack or obstruction in sur ace 2 • causing air to enter the cup, the pressure differential will move valve member 60 to a closed position relative to hole 44 to prevent the air entering cup 39 from flowing to the manifold block 28.

The robotic device, as illuεtrated in Figs. 1 and 2, can be uεed to move a working implement or attach- ment 61 across the surface 2 to be treated. The attach¬ ment 61 includes a frame 62, which is pivotally connected to a pair of lugε 63 that extend rearwardly from general¬ ly L-shaped brackets 64, that are connected to the rear frame member 12, aε beεt in Fig. 2. Three yokeε 66 are connected to frame 63 and a rotary buffer 67 iε mounted for rotation in each yoke 66. The bufferε 67 are design¬ ed to be individually rotated by drive motors located internally of the buffers, not shown. Suitable εhieldε 68 are connected to the yokeε and extend partially over the bufferε 67 to confine εpray from the buffers.

The buffers 67 are urged downwardly into con¬ tact with εurface 2 by an air cylinder unit 69. Cylinder unit 69 includes a cylinder 70 and a rod 72 is connected to one end of the cylinder and iε pivotally connected to a pair of lugε 73 which project upwardly from houεing 3. A piston is εlidable within cylinder 70 and a piεton rod 74, which iε connected to the piεton, extends from the opposite end of the cylinder and is pivotally connected to lugs 75 that extend upwardly from frame 62. By extending cylinder unit 69, down presεure can be applied through buffer 67 to εurface 2. By retracting the cylin¬ der unit 69, the frame 62 and bufferε 67 can be pivoted upwardly out of contact with surface 2, as shown by the dashed lines in Fig. 1.

While the drawings illuεtrate the working imple entε to take the form of rotary buffer 67, it iε contemplated that variouε typeε of working implements can be subεtituted, εuch as scrubberε, waxerε, paint applic- atorε and the like.

Aε a feature of the invention, a provision is incorporated to prevent the robot from falling from a vertical or inclined surface 2 in the event there is a failure in the vacuum system. In this regard, a fan 76 is mounted in the opening in flange 7 which extendε up¬ wardly from houεing 3. Fan 76 includes a hollow vertical shaft 77 which is driven by a motor 78. Motor 78 is supported within the opening in flange 7 by a serieε of diametrically extending braces 79.

A sensor, not shown, will sense the magnitude of the vacuum or negative pressure in the vacuum system. If the vacuum decreases to a pre-selected value, the fan 76 will--be operated to create a negative pressure within the housing 3 to prevent the robot from falling from surface 2. The brush seal 11 which is mounted on the peripheral edge of the housing 3 and is engaged with the εurface 2, cooperateε with the fan to enable a negative preεsure to be created within the housing.

Fig. 7 illustrates a preferred embodiment of the invention in which the robot 1 is utilized for non¬ destructive inspection of an aircraft. In this embodi¬ ment, the retro-reflector or cat's eye 9 is mounted on the upper end of a rod 80 that is slidable within the hollow fan shaft 77. The lower portion of rod 80 extends freely through motor 78 and the lower end of the rod 1 is provided with a senεor or εhoe 82, which iε adapted to ride on the εurface 2 of aircraft 83. Senεor 82 is biased downwardly againεt the aircraft εurface 2 by a coil εpring 84, which iε interpoεed between the motor 78 and the upper εurface of the sensor. In the non-destructive inspection system, one or more robots 1 are mounted to travel acroεε the surface of the aircraft 83, aε illustrated in Fig. 8. In prac¬ tice, three robots 1 can be utilized along with six laser tracking units 85 when inspecting a large commercial aircraft. As shown in Fig. 7, a movable carriage 86 is asεociated with each robot and includeε a vacuum pump, that iε connected by a εuitable conduit 87 to the manifoldε 28 on the robot. In addition, electric feed lineε not shown, are connected between the carriage 86 and the robot 1. As illustrated in Fig. 7, one of the carriages 86 is mounted to travel on an overhead track 88 and is connected to a robot 1 which iε adapted to move acroεε the upper εurfaceε of the aircraft 83, while a εecond carriage 85 travelε on the ground and iε operably connected top a second robot 1 that traverseε the lower surface of the aircraft.

In carrying out the non-destructive inεpection, the vacuum εystem is initially εtarted to create a vacuum in the-vacuum cupε and enable the robot to adhere to the εurface of the aircraft 83. The aircraft haε certain tooling locationε, or depressionε, located at variouε poεitions on the buoyancy line, which are used as refer¬ ence points to take dimenεionε during the manufacture and εet-up of the aircraft. Theεe depreεεed reference points are generally referred to as fiducialε. Through a radio controlled unit, the motorε 24 on the robot 1 are then actuated to move the robot over the aircraft εurface until the sensor 82 is engaged with a fiducial. Through the computer of the laser εyεtem, thiε iε eεtabliεhed aε an origin point.

Aε a large aircraft generally haε a number of fiducialε, the robot iε moved and engaged with each fidu¬ cial to obtain a εerieε of origin points. The desired operating program as selected in the computer, then actuates the program to operate the motors 24 to move the robot in the desired path of travel on the aircraft εurface. At this time, the interior of the aircraft is under atmospheric presεure.As the robot moves across the aircraft surface the εenεor 82 will ride on the εurface and will move relative to the frame of the robot.

As described in the tracking system of U.S. Patent No. 4,714,339, a laser beam is directed from tracking unit 85 to the target, which iε the retro- reflector 9 mounted on houεing 3, and the retro-reflector reflectε a beam back to a tracking unit 85. Photosenεorε attached to the tracking unit 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 9 can be continuously determined, thus providing a surface map of the aircraft.

After the surface mapping of the entire air¬ craft has been completed, the interior of the aircraft iε then preεsurized at about 1 atmosphere of pressure and the surface mapping operation is repeated. If any por- tion of the aircraft surface 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 rivet. Any potential defective area can then be manually inspected. By using the robot 1 in conjunction with a laser tracking system, surface mapping of the aircraft can be accomplished to determine potential areas of defect without the neceεsity of stripping paint from the aircraft surface and without the need of a manual inεpec- tion of the entire aircraft εurface. As the paint εtrip- ping, manual inspection, repainting and waxing operations are eliminated, the overall time and cost for the inspec¬ tion is greatly reduced.

Aε a further and important advantage, the invention eliminates the need of incorporating pollution control equipment, which is necessary for normal paint stripping operations. Stripping of the paint from a large commercial aircraft, εuch aε a Boeing 747, normally requireε more than 1,000 gallons of solvent, εuch aε methylene chloride. Aε the solvent is toxic, and createε a potential environmental hazard, pollution control equipment iε neceεsary to restrict the escape of solvent vaporε.

It iε preferred that trackε 18, as well as frame 4, be conεtructed of flexible plaεtic material εo that the robot can conform to contoured εurfaceε.