Abstract:
A remotely controlled, traction wheel driven, transporter moves inspection equipment within a walled cavity to check internal structural features. The inspection equipment can be mounted on a positioner pushed by the transporter, which adjusts with changing dimensions of the cavity so as to maintain the inspection equipment in a desired position or attitude, for example, centered within the cavity.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    This invention broadly relates to inspection devices and related fixtures, and deals more particularly with an apparatus for transporting and positioning an inspection device within a walled cavity, such as inside an aircraft wing. 
         [0003]    2. Description of the Related Art 
         [0004]    A wide variety of new technologies are now employed to detect defects and measure or verify structural features within closed volumes or cavities in large and bulky manufactured items. For example, aircraft wings may be constructed using multi-spar internal boxes formed of co-cured composite materials. These wing boxes have walls defining long cavities which may be 40 or more feet in length. In some cases, the cross section of the cavity may change in dimensions and/or directions along its length. For example, the cavity within a horizontal stabilizer box may taper from approximately 2 feet in cross section to 6 or 7 inches over a 40 foot length. 
         [0005]    In the context of the aircraft industry, features of a stabilizer box requiring inspection or verification include internal dimensions, the position of radius corners, the location of holes used for fasteners and similar structural features that are critical for quality or assembly. In order to inspect and measure these features, verification technologies including cameras, laser line measurement, laser dot scanning, and other nondestructive inspection techniques are used. 
         [0006]    A problem may arise, for example, in gaining access to locations within the horizontal stabilizer box along its length using the selected verification equipment. Gaining inspection access is compounded by the fact that it is often necessary to position the verification equipment within the stabilizer box cavity, and then maintain this position as the equipment is moved along the length of the cavity. For example, some measurement devices must be precisely positioned in the corners of the cavity along its length, while other measurement equipment such as a laser scanner and cameras need to be located at the center of the cavity, even when the cavity changes cross sectional dimensions along its length. 
         [0007]    Transport mechanisms have been developed that are capable of carrying inspection equipment through a large cavity. For the most part, these cavities are well ordered geometries such as circular pipes or square tubes. However known mechanisms may be ineffective in centering or precisely positioning inspection equipment within a cavity that is not well ordered such as a tapering rectangle or rhombic geometry. Moreover, while known camera inspection systems are used to image features in remote areas within the cavity, these systems cannot accommodate drastic changes in cross sectional dimensions of the cavity as its length is traversed. Similarly, these prior inspection systems may not be able to move around partial barriers that may be encountered within the cavity, such as bulkheads or spars. 
         [0008]    Accordingly, there is a need for a system for transporting and positioning inspection and measuring equipment within cavities that avoid the problem discussed above. The invention is directed towards satisfying this need. 
       BRIEF SUMMARY OF THE INVENTION 
       [0009]    In accordance with one aspect of the invention, an apparatus is provided for remotely positioning an inspection device within a walled cavity, comprising a positioner for carrying the inspection device, and a transporter connected with the positioner for moving the positioner through the cavity. The positioner includes a central hub and a plurality of extendable arms pivotally connected to the hub for supporting and maintaining the hub in a central position within the cavity. Wall engaging members such as rollers are mounted on the ends of the arms to engage the cavity walls. Biasing means comprising a spring or pneumatic piston, urge the arms to pivot outwardly into engagement with the wall so as to support and maintain the central hub in a central position within the cavity. The inspection device may be carried on a central hub or any of the arms. The arms are arranged in pivotally connected pairs forming collapsible scissor mechanisms which extend or collapse diagonally within the cavity so as to accommodate changing cross sectional dimensions of the cavity. The central hub comprises a shaft and a pair of supports relatively slidable on the shaft. The scissors-like, extendable arms are pivotally connected to the supports such that sliding movement of the supports extends or collapses the arms within the cavity. 
         [0010]    In accordance with another aspect of the invention, apparatus is provided for carrying an inspection device through a walled cavity, comprising a hub assembly; a plurality of arms pivotally mounted on the hub assembly for supporting the hub assembly in a central position within the cavity; rollers for engaging the cavity walls and allowing the apparatus to roll through the cavity; and biasing means for biasing the arms outwardly toward the walls so that the rollers maintain engagement with the walls. 
         [0011]    In accordance with still another aspect of the invention apparatus is provided for moving an inspection device through a walled cavity. The apparatus comprises a central support; a plurality of extendable arm assemblies carried on the support for maintaining the support centered within the cavity, wherein each of the arm assemblies includes an outer end for engaging a cavity; and, biasing means for biasing the outer ends of the arms against the cavity walls. Each of the arm assemblies includes at least one roller for engaging and rolling along one wall of the cavity. The arm assemblies are arranged in a plurality of diagonal pairs forming scissors mechanisms which maintain the central support centered within the cavity while accommodating changes in cross sectional dimensions of the cavity. 
         [0012]    The transporter and positioning system of the invention is advantageous in that inspection equipment can be precisely positioned within the cavity throughout its entire length, irrespective of changes in the cross sectional dimensions of the cavity or changes in the direction of the cavity. Inspection equipment can be mounted on the central support so as to remain centered within the cavity, or alternatively can be mounted on one of the extendable arms to perform inspection of corner features. 
         [0013]    These and other features, aspects and advantages of the invention will become better understood with reference to the following drawings, description and claims. 
     
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
         [0014]      FIG. 1  is a perspective view showing one open end of a multi-spar box forming part of a horizontal stabilizer for an aircraft. 
           [0015]      FIG. 2  is a fragmentary, cross sectional view of the multi-spar box show in  FIG. 1 , better depicting the profile of the internal box cavity. 
           [0016]      FIG. 3  is an enlarged, fragmentary view of the area designated by the numeral  30  in  FIG. 2 . 
           [0017]      FIG. 4  is a perspective view of the transporter of the invention having a laser scanner mounted thereon. 
           [0018]      FIG. 5  is a perspective view of the transporter having a camera mounted thereon. 
           [0019]      FIG. 6  is a perspective view of the transporter having a hitch used to connect the transporter with the positioner. 
           [0020]      FIG. 7  is a perspective view of the transporter, shown pushing the positioner into a cavity of the multi-spar box shown in  FIG. 1 . 
           [0021]      FIG. 8  is a perspective view of the positioner forming one embodiment of the invention. 
           [0022]      FIG. 9  is a perspective view of one end of the positioner shown in  FIG. 8 . 
           [0023]      FIG. 10  is an enlarged, fragmentary view of one corner of a cavity of the multi-spar box shown in  FIG. 1 , and depicting the end of one of the positioner arms engaging the walls of the cavity. 
           [0024]      FIG. 11  is a perspective view of a positioner forming another embodiment of the invention using a pneumatic rather than spring loading mechanism. 
           [0025]      FIG. 12  is a cross sectional view of one of the cavities in the box shown in  FIG. 1  and depicting a corner inspection device carried on a positioner arm. 
           [0026]      FIG. 13  is a block diagram of a system for controlling the transporter and positioner of the invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0027]    Referring first to  FIGS. 1-3 , the invention involves apparatus for transporting and positioning inspection equipment within walled cavities such as those found within a multi-spar stabilizer box  20  which forms part of a horizontal stabilizer for an aircraft. The multi-spar stabilizer box  20  may be formed from top and bottom walls  22 ,  24  respectively connected by a series of spaced apart side walls  26  which form a series of elongate cavities  28 . The cavities  28  may taper in cross sectional dimension from the proximal end shown in  FIG. 1  to smaller cross sectional dimensions at the distal end. In some constructions of the stabilizer box  20 , the direction of the central axis of a cavity  28  may change at some point along its length. 
         [0028]    As best seen in  FIGS. 2 and 3 , the cavity walls  22 ,  24 ,  26  may comprise co-cured composite materials that possess various internal structural features requiring inspection, verification or measurement. For example, as shown in  FIG. 3 , the corners  30  may typically include the following structural features which must be verified or measured: 
         [0029]    R=radius 
         [0030]    FL=flange length 
         [0031]    FT=flange thickness 
         [0032]    FA=flange angle 
         [0033]    SA=spar angle 
         [0034]    EM 1 =edge margin # 1   
         [0035]    EM 2 =edge margin # 2   
         [0036]    In addition, camera or other inspection equipment may need to verify the presence of a through-hole  23  which later receives a fastener (not shown). As used herein, “inspection” devices or equipment is intended to include various equipment and technologies intended to either verify, measure or inspect structural features within the cavity  28 . 
         [0037]    Referring now to  FIG. 4-6 , the invention includes a transporter  32  having an elongate frame  34  on which there is mounted a pair of driven traction wheels  36 , and a single, forward wheel  38  which is swively mounted on the frame  34 . The traction wheels  36  are driven respectively by a pair of electric stepper motors  40  whose output shafts  42  drive wheels  36  by means of a drive belt  44 . Stepper motors  40  are independently controllable, allowing the drive wheels  36  to steer the transporter both forwardly and rearwardly through the cavity  28 . 
         [0038]    As will be discussed later in more detail, the transporter  32  may be used to carry inspection equipment through the cavity  28 , or to push a later discussed positioner through the cavity  28  on which the inspection equipment is mounted. As shown in  FIG. 4 , a laser scanner  46  is rotatably mounted at  37  on one end of the frame  34  and is connected with a central motor  35  that rotates the laser scanner  46  inside the cavity  28 .  FIG. 5  shows the use of a camera  48  mounted on one end of the frame  34 , which is used to image structural features within the cavity  28 . 
         [0039]      FIG. 6  shows another embodiment of the transporter  32  in which a hitch  52  is mounted on one end of the frame  34  and includes a clevis  54  for releasably connecting the positioner  56  of the invention to the transporter  32 . 
         [0040]    As shown in  FIG. 7 , the inspection equipment positioner  56  includes a central shaft  68  connected with the hitch  52  so that the transporter pushes the positioner  56  through the cavity  28 . 
         [0041]    Referring concurrently to  FIGS. 7-9 , the positioner  56  broadly comprises a central hub assembly  65  on which there is pivotally mounted eight extendible arms  58  arranged in four pairs  59 , wherein each pair  59  is pivotally connected to form a mechanism with a scissors-like motion. The pairs  59  of arms  58  may extend diagonally outward from the central hub assembly  65 , toward the corners of the cavity  28 . More specifically, the central hub assembly  65  comprises a central rigid shaft  68  on which there is mounted a pair of cross beam supports  64 ,  66  having legs  71  that extend radially outward from the shaft  68 . Cross beam support  64  is attached to one end of the shaft  68 , while the other cross beam support  66  is slidable on the shaft  68 , toward and away from cross beam support  64 . A biasing means, in the form of an elastic band  92 , may be trained around facing legs  71  of supports  64 ,  66  and functions to bias support  66  toward support  64 . Various other means for producing the biasing force may be used, including one or more springs, pneumatic actuators or other forms of force applying mechanisms. 
         [0042]    Each of the arms  58  has its inner end connected to a leg  71  of a cross beam support  64 ,  66  at a pivot point  70 . The outer ends of arm member  58  in each pair  59  thereof are pivotally connected by a pair of parallel links  60  at pivot points  72 . Medial portions of the arm members  58  in each pair  59  thereof are pivotally connected with each other at pivot points  67 . Thus, it can be appreciated that each pair  59  of the arms  58 , the legs  71  of the supports  64 ,  66  and links  60 , comprises an assembly that roughly approximates a parallelogram in configuration. The outer ends of links  60  angle outwardly to form a ninety degree angle with respect to each other and have mounted thereon a wheel or roller  62  which, as shown in  FIG. 10 , is intended to engage a corresponding wall  24 ,  26  of the walled cavity  28 . 
         [0043]    In use, the transporter  32  pushes the positioner  56  into and through the cavity  28 , acting under remote control. As the positioner  56  enters the cavity, the biasing means, in this example elastic member  92 , urges support  66  to slide on shaft  68  toward support  64 . The linear motion of support  66  may translate to each pair  59  of arms  58 , causing arm members  58  to move outwardly until the wheels  62  engage walls  22 ,  24 ,  26  in cavity  28 . The biasing means  92  urges the wheels  62  into contact with the walls  22 ,  24 ,  26  so as to maintain contact, preferably constant contact, therewith. As the cross sectional dimensions of the cavity  28  change, the arms  58  may either extend further outwards, or move inward. As the arms  58  overcome the force of the biasing means  92 , support  66  is caused to slide on shaft  68 , away from support  64 . When the diagonally extending pairs  59  of arms  58  contact two walls defining a corner of the cavity  28 , the central hub assembly  65 , and the shaft  68  remain within a central region of the cavity  28 . Thus, an inspection device mounted on the shaft  68  remains in the central region within the cavity  28 , even though the walls of the cavity may converge or diverge. 
         [0044]    Any of numerous inspection devices of the type previously mentioned may be mounted on the shaft  68 , as described above. However, one or more inspection devices may also be mounted on the arms  58 , depending upon the feature that is to be measured or inspected. For example, as shown in  FIG. 10 , a non-contact measurement device  78  such as a camera or laser may be mounted on arm member  58  and is used to inspect the size or location of a through hole  80  in cavity wall  76 . Similarly, as shown in  FIG. 12 , a laser inspection device  114  may be mounted either on arm members  58  or links  60  when it may necessary to measure the radius of a corner  116 . Finally, at least one arm  58  may be replaced by an inspection device (not shown) which is mounted on the shaft  68 . 
         [0045]    Attention is now directed to  FIG. 11 , in which an alternate form of the positioner  56   a  is shown. Positioner  56   a  includes a central hub assembly  85  comprising a central shaft  68  having a support  64  attached to one end thereof. A cylindrical support  84  may slide on the opposite end of the shaft  68 . The shaft  68  may be connected to a pneumatic cylinder assembly  82  which linearly displaces the shaft  68 , causing the latter to slide through support  84 . Linear displacement of shaft  68  likewise displaces support  64 . Connected between support  64  and support  84  and  86 , may be four pairs  87  of arms  88  extending diagonally from shaft  68  and pivotally connected at their medial sections at a pivot point  100 . The outer ends of arms  88  are connected by links  90  having rollers  62  on its opposite ends. The links  90  each include a slot  94  receiving a guide pin  96  on the outer end of one of the arms  88 . In effect, the slot  94  and pin  96  form a lost motion mechanism so that the wheel  62  on each link  90  remains in contact with a cavity wall  22 ,  24 ,  26  as transporter  32  traverses the cavity  28 , regardless of changes in the distance between the walls. 
         [0046]    In use, the pneumatic cylinder  82  applies a retraction force to shaft  68 , thereby biasing support  64  to move toward the right as viewed in  FIG. 11 . As support  64  retracts toward support  84 , the outer ends of the arms  88  move toward each other, forcing the links  90  outwardly so that the wheels  62  may be urged against the cavity walls  28 . The force applied by the pneumatic cylinder  82  is selected such that the arm members  88  can collapse, at least partially. Collapsing of the arm members  58  accommodates narrowing distances between the cavity walls  28 , which force the links  90  inwardly, toward the central hub assembly  95 . As previously mentioned, the combination of the slots  94  and pins  96  assure that both rollers  62  on each link  90  remain in contact with a cavity wall. 
         [0047]    Attention is now directed to  FIG. 13  which depicts a system for controlling the transporter  32  and the positioner  56 . Broadly, the transporter  32  comprises an onboard controller  106  which may include a microprocessor controller, for example and appropriate programmed instructions and/or firmware for controlling stepper motors  40  which drive the traction wheels  36 . The position of the transporter  32  within the cavity  28  may be controlled by the controller  106 , since the location of the transporter  32  is a function of the rotation of stepper motors  40 . A flexible conduit  50  connects a stationary PC (personal computer)  104 , located outside the cavity  28  with both the transporter  32  and positioner  56 . The conduit  50  may house both electrical and pneumatic lines. The controller  106  may route signals from position sensors  108  or measurement devices  110  from the transporter  32  back to the PC  104 . 
         [0048]    The PC  104  may be used to control the pneumatic cylinder  86  on positioner  56  in order to control the force applied to the arms. Signals from measurements devices  112  carried on the positioner  56  may be relayed through the PC  104  via the tether  50 . 
         [0049]    Although this invention has been described with respect to certain exemplary embodiments, it is to be understood that the specific embodiments are for purposes of illustration and not limitation, as other variations will occur to those of skill in the art.