Abstract:
An apparatus is disclosed for climbing objects such as trees, poles, pipes, and the like. The apparatus includes at least one actuator with at least two clamps operatively attached to the actuator. Each of the clamps has an opening, which is at least as large as the cross-sectional measurement of the object being climbed. Links are attached to the clamps. A controller directs operation of the climbing apparatus.

Description:
[0001] This work was funded in part by the Defense Advanced Research Projects Agency (DARPA), Contract #MDA972-98-c-0009. The U.S. Government may have certain rights in this invention. 
     
    
     
       INCORPORATION BY REFERENCE  
         [0002]    The following U.S. patents are fully incorporated herein by reference: U.S. Pat. No. 4,793,439 to Crawford (“Apparatus for Climbing Trees, Poles and the Like and Being Remotely Controlled from Ground Elevation”); U.S. Pat. No. 5,301,459 to Eliachar et al. (“Tree Climbing Device”); and U.S. Pat. No. 5,799,752 to Perry (“Climbing Device”).  
         BACKGROUND OF THE INVENTION  
         [0003]    This invention relates generally to a climbing device and the like and specifically to a device for climbing poles, trees, and other tall structures, as well as pipes and irregular structures.  
           [0004]    The technology available for power line/telephone maintenance, tree surgery, pipe maintenance, repair of high-masted poles (such as light poles) has utilized various approaches in accessing elevated locations to perform specific tasks. For example, devices such as pole and tree ladders provide support to a user as they climb a tree or pole. One such device is disclosed in U.S. Pat. No. 5,799,752 to Perry. In Perry, a clamp engages three sides of a tree trunk, gripping the tree between opposed arms of the clamp to which is attached a ladder. Apart from using ladders, trees or poles are scaled through the use of hand lines and/or climbing spurs. Lifting devices, which a person is raised to various heights, have also been employed, but these devices are expensive and slow-moving.  
           [0005]    U.S. Pat. No. 5,301,459 to Eliachar et al. provides an alternate approach for climbing trees having straight trunks and no branches. The device of Eliachar, which is directed to the maintenance of palm trees, employs two pairs of arms, which are capable of opening and closing around a tree trunk and of climbing the tree trunk through the activation of hydraulic cylinders. Operation of the climbing unit is directed by a programmable controller. A remotely-controlled device for positioning equipment at working elevations is taught in U.S. Pat. No. 4,793,439 to Crawford. The apparatus of Crawford employs a frame having operating arms which at least partially encircle the tree or pole and secure the frame to the tree. A hydraulically driven telescoping mast also is equipped with gripping arms, which are hydraulically actuated independently of the gripping arms of the main frame. The gripping arms of the main frame and the hydraulically driven telescoping mast are sequentially activated to cause the apparatus to climb a tree or pole. The gripping arms fully retract to permit the apparatus to pass between limbs. A winch and cable system controlled by operating personnel provides for lifting objects, such as tools, to the working level or for lowering objects, such as cut branches, to the ground.  
           [0006]    However, there are numerous disadvantages to existing approaches for scaling tall structures for repair or maintenance. There is a significant possibility that when using climbing spurs, ladders, etc., personnel may fall. Hand lines may slip or break, or a limb could break, possibly falling on personnel or damaging objects at the surface. Some approaches, such as cranes, are costly, their operation is slow, and they require sufficient ground clearance for maneuvering the cab and for vertical movement of the lifting arm and cradle. Existing remotely controlled devices have been narrowly directed to the movement of tools to a work location or to the maintenance of specific types of trees. It is desirable to provide an apparatus that is capable of safely and efficiently climbing trees, poles, posts, pipes, etc. while being under the control of personnel at ground level, and, when in position, performing varied maintenance and/or repair tasks.  
         SUMMARY OF THE INVENTION  
         [0007]    Briefly stated, and in accordance with one aspect of the present invention, there is disclosed an apparatus for climbing objects such as trees, poles, pipes, and the like. The apparatus includes at least one actuator with at least two clamps operatively attached to the actuator. Each of the clamps has an opening, which is at least as large as the cross-sectional measurement of the object being climbed. Links are attached to the clamps. A controller directs operation of the climbing apparatus.  
           [0008]    In accordance with another aspect of the invention, there is disclosed a method for operating a climbing device, which has at least one actuator, at least two clamps operatively connected to at least two links, and a controller. The method includes engaging a structure to be climbed in at least two locations with the clamps. One of the clamps is brought into a perpendicular position relative to the structure and then disengaged from the structure. The disengaged clamp is then moved to a second position along the structure that is closer to an engaged clamp, at which point the disengaged clamp re-engages the structure. A different clamp is then brought into perpendicular relationship with the structure and then disengaged from the structure. This clamp is then moved to a position more distant from the other now engaged clamp and re-engages the structure. This sequence of motions is repeated until a desired location is reached on the structure. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0009]    The foregoing and other features of the instant invention will be apparent and easily understood from a further reading of the specification, claims and by reference to the accompanying drawings in which:  
         [0010]    [0010]FIG. 1 illustrates the clamping mechanism of the subject invention in its unclamped position;  
         [0011]    [0011]FIG. 2 illustrates the clamping mechanism of the subject invention in its clamped position;  
         [0012]    [0012]FIG. 3 illustrates the operational steps for the apparatus of the subject invention;  
         [0013]    [0013]FIG. 4 illustrates the engaged and unengaged positions for the clamping mechanism according to the subject invention;  
         [0014]    [0014]FIG. 5 illustrates the operation of the apparatus of the subject invention as it moves around obstacles in its path; and  
         [0015]    [0015]FIG. 6 illustrates alternate embodiments for the clamp portion of the subject invention. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0016]    The climbing apparatus and method disclosed herein provide the capability for accessing elevated sites, which a human cannot reach without difficulty or without encountering safety risks. Such sites include, but are not limited to, structures that will not support the weight of a person, areas that may be obstructed (for example, deep into a tree or a bridge), or locations close to high voltage lines. Several characteristics are necessary in a device to access these sites, such as the ability of the device to grip and release the structure it is climbing as well as the ability to move at least bi-directionally along the structure being scaled. FIG. 1 provides a simplified diagram of one embodiment of the clamping mechanism disclosed herein and its manner of engaging the structure. In the side view in this figure, structure  110  is engaged by clamping mechanism  120  to which load  130  is attached. The top view shows clamp  120 , which may generally take the form of a “C” in its engaged but unclamped position around structure  110 .  
         [0017]    As will be appreciated by those skilled in the art, clamp  120  may take other forms, as illustrated in FIG. 6. Forms generally angular or rectilinear in shape or those combining curvilinear and rectilinear features would also provide sufficient engagement with the structure being climbed, all of which are contemplated by this disclosure and the scope of the claims herein. The preferred size for the open end of the clamp would be any size larger than the diameter or cross-section of the structure being climbed. Of course, if the clamp opening is substantially larger than the diameter of the structure, the angle at which the clamp effectively grabs the pole increases. The climbing apparatus may either assume that it is properly engaged, in those configurations operating open loop without sensing, or contact, touch, or force sensors may be incorporated into the climbing apparatus to ensure proper engagement. If improper engagement is sensed, control software reacts to this and applies appropriate measures such as re-attempting engagement or attempting engagement at a different location.  
         [0018]    Referring now to FIG. 2, the operational position of the clamp is illustrated. In the side view of the operational position, clamp  220  engages structure  210 , with clamp  220  supporting load  230 . In the top view, clamp  220  is seen gripping structure  210 , which results when clamp  220  is inclined such that the angular cross-section of the engaged portion of structure  210  interferes with the internal diameter of clamp  220 .  
         [0019]    Turning now to FIG. 3, the sequence of operations enabling the climbing mechanism to move along a structure is illustrated. At the first step, clamps  320  and  340  are in engaged positions on structure  310 , with linkages  330  connecting clamps  320  and  340 . Example materials from which the clamps and linkages may be fabricated include metals, woods, plastics, or other rigid or semi-rigid materials.  
         [0020]    Initially clamp  340  releases as it reaches a position perpendicular to structure  310  while clamp  320  remains clamped to structure  310  and linkages  330  are in an extended configuration to maximize the distance between the connected ends of clamps  320  and  340 . At step two, linkages  330  move to an angular position relative to each other, thus reducing the distance between clamps  320  and  340  by moving clamp  340  closer to clamp  320 . Clamp  340  remains in its released or unclamped position while clamp  320  remains in its clamped position. At step three, clamp  340 , which has moved to a new location on structure  310 , becomes clamped to structure  310 . Clamp  320  remains in its original clamped position and linkages  330  remain in angular relationship to each other. At step four, clamp  320  releases the structure by moving to an approximately perpendicular position relative to structure  310 . Clamp  340  remains in its clamped position and linkages  330  retain their angular relationship to each other.  
         [0021]    At step  5 , linkages  330  have moved to a fully extended position, which maximizes the distance between the attached ends of clamps  320  and  340 . Clamp  340  remains in its clamped position and clamp  320 , in its unclamped configuration, moves along structure  310 . Finally, at step  6  clamp  320  clamps to structure  310  at its new position. Clamp  340  remains clamped to structure  310  and linkages  330  remain in a fully extended configuration. At this point the sequence of steps may be repeated to continue movement of the climbing mechanism along the structure. Although only two links are illustrated in the figures herein, it will readily be appreciated that in an alternate embodiment more than two links could be beneficially employed to move the apparatus along a surface. The motor causing the movement of the links is included within the structure of the links. A controller (not shown) may be either included in the structure, attached separately to the structure, or included in a remote control module.  
         [0022]    In addition to moving along a structure, an alternate embodiment of the apparatus described herein is capable of moving around obstacles on a structure by engaging and disengaging the structure as needed. Referring to FIG. 4, there is shown clamp  420  in both clamped and unclamped configurations around structure  410 . In both cases clamp  420  is connected to a linkage at attachment point  450 , which also holds the actuator which enables movement of clamp  420  in a plane perpendicular to the structure.  
         [0023]    [0023]FIG. 5 illustrates another possible configuration for this embodiment as the climbing apparatus moves along a structure. Here climbing apparatus  500  includes at least three clamps  520 ,  540 , and  560  connected by linkages  530 . In this embodiment the clamp encountering obstacle  570  on structure  510  disengages from structure  510  while the remaining clamps continue moving along the structure. Examples of obstacles  570  include branches and attachments to the structure. Although three clamps connected with two linkages between each clamp are illustrated, it will be appreciated that a plurality of clamps and linkages may be utilized in the climbing apparatus and such configurations are fully contemplated by this specification and the scope of the claims herein. In FIG. 5 clamp  520  has already encountered obstruction  570 , disengaged from structure  510  as clamps  560  and  540  continued to move apparatus  500  along structure  510 , and then re-engaged with structure  510 . Apparatus  500  then continued moving along structure  510  until clamp  560  encountered the obstacle. As illustrated in FIG. 5, clamp  560  then disengages from structure  510  to clear the obstacle while clamp  520  remains in its clamped position and clamp  540  has moved to a perpendicular relationship with structure  510  preparatory to moving along the structure. Complete disengagement with the structure is accomplished without sensors through translation of the clamp through a specified range of movement. For those embodiments in which sensors are included, sensors measure either the change of forces internal to the structure, or touch, force, or contact sensors detect disengagement.  
         [0024]    As described above, linkages  530  move from angular to fully extended positions to enable movement of apparatus  500  along the structure. When the climbing apparatus  500  has moved sufficiently for clamp  560  to clear obstruction  570 , clamp  560  swings back into engagement with structure  510 . When clamp  520  encounters the obstacle, it disengages and swings away from structure  510  as clamps  560  and  540  continue to climb. When clamp  560  encounters the obstacle, clamps  520  and  540  remain engaged and continue climbing while clamp  560  is disengaged. When clamp  540  encounters obstacle  570 , clamps  520  and  560  continue climbing as clamp  540  disengages from structure  510 . This engagement and disengagement sequence of movements enables the apparatus to transition from climbing to translation along a horizontal bar or a horizontal cable.  
         [0025]    For those embodiments in which the apparatus is remotely controlled, an operator directs the movement of the apparatus to clear an obstacle. For those embodiments in which the apparatus operates autonomously, touch, force, or contact sensors sense contact with the obstacle. The on-board controller then causes the colliding arm to move out of the way of the obstacle. The on-board controller may then either continuously attempt re-engagement as the rest of the system climbs (for example, repeatedly touching and sensing the obstacle until the obstacle is cleared), or it may sense the obstacle without contact, through proximity sensing.  
         [0026]    While the present invention has been illustrated and described with reference to specific embodiments, further modification and improvements will occur to those skilled in the art. For example, the apparatus is also able to move along structures that are semi-flexible or not precisely straight, such as piping, which includes bends or curved structural supports. It is to be understood, therefore, that this invention is not limited to the particular forms illustrated and that it is intended in the appended claims to embrace all alternatives, modifications, and variations which do not depart from the spirit and scope of this invention.