Abstract:
A power hand-tool support apparatus includes a multi-component articulating arm with pneumatic lifting assist to hold the hand-tool and protect the operator from tool induced torque, the apparatus equipped with positional feedback means, such as optical encoders, to communicate with a dedicated control unit to define a selectable datum position of the hand-tool in the work-space with a lock-out of the tool if the positions do not comply with programmed tightening sequences on bolt patterns.

Description:
FIELD OF THE INVENTION  
         [0001]    This invention is directed to an apparatus used at an industrial workstation that includes a hand tool holding device. More particularly the apparatus may include a positional feedback mechanism that provides the tool position and is adapted to be connected to a controlling mechanism and even more particularly may include torque feedback resistance to protect the operator from undue strain and a balancing mechanism to assist lifting the tool.  
         BACKGROUND OF THE INVENTION  
         [0002]    Electric and pneumatic powered hand tools are commonly used on assembly lines and assembly stations in industrial manufacturing settings. These tools include drivers for bolts, nuts, screws and like fasteners. While some manufacturing techniques are adaptable to robotic systems, many utilize an operator wielding a powered hand tool. The assembly of a work piece typically involves numerous steps and includes a multiplicity of riveting, threading, and tightening various types of fasteners usually in a particular order and in a three dimensional space around the work piece. Thus it is not uncommon for dozens of differing types and sizes of fasteners to be installed on a particular job with the requirements that the installation and tightening of the fasteners must be in certain prescribed order, or else the stress placed on the parts by tightening a fastener out of order might induce a crack or other failure. Rigorous training is required to attempt to control the operator and reduce the chance of error. However, mistakes occur resulting in breakage during manufacture or later failure due to stresses placed in the part by incorrect installation during manufacture. The prior art has failed to successfully address these problems.  
           [0003]    Optical encoder devices that digitally measure an angular position have been used in industrial manufacturing applications, most notably in robotic controlled and operated systems. However, these devices have not been used to attain the objects described herein below and in the present invention.  
           [0004]    Present power tool balancers and anti-torque tool holding devices have inadequate balance control effectiveness and allow substantial torque feed back to the operator when the tool is in some positions. For example, when the tool is supported on an arm that includes a plurality of universal joints, each of which allows rotational movement in one plane, alignment of the torque at certain angles with these planes can result in some torque feedback to the operator. Spring loaded balance mechanisms are commonly used tool suspension apparatuses, but these are difficult to control and adjust to changing conditions such as the weight of the tool and individual operator preferences. Some operators prefer that the system require some lifting of the hand-tool and others prefer that some pulling down of the tool against the spring tension be required for operation. Since operators change at the end of shifts and sometimes during the shifts, adjustment is cumbersome, at best time consuming and may not be available at all.  
           [0005]    U.S. Pat. No. 5,791,619 to Myers discloses an anti-torque tool suspension arm using a splined axially extensive arm in and axially extensive housing cavity with a splined hub insert to “largely eliminate play between the rod and housing. U.S. Pat. No. 6,054,373 to Watanabe, et al. discloses a power tool holding assembly that includes piston-cylinder linear movement guiding unit with a ball spline with a piston rod. U.S. Pat. No. 5,213,292 to Evans discloses a tool balance using springs. U.S. Pat. No. 5,580,021 to Gillanders discloses a suspension mechanism for a hand-manipulated power-tool wherein the suspension tension is relieved when the tool is actuated. U.S. Pat. No. 5,109,736 to Dixon discloses power screwdriver on a cantilevered support movable on a worktable with power assist up and down. U.S. Pat. No. 5,544,554 to Brightly discloses a pneumatic torque wrench mounted on a torque arm, which is locked in place when the wrench is engaged allowing the operator to remove hands when the torque is applied. U.S. Pat. No. 6,324,728 to Blankenheim discloses an ergonomic attachment for inline power tools that includes an inverted U-shaped member that is forced downwardly on the forearm of the operator.  
           [0006]    None of these devices satisfy the needs addressed herein and satisfy the objects of this invention.  
         SUMMARY OF INVENTION  
         [0007]    It is an object of an embodiment of the present invention to provide a device, including those described herein above and below that will support and hold a powered hand-tool that can be freely moved throughout a three-dimensional workspace.  
           [0008]    It is a further object of an embodiment of the present invention to provide an articulated arm device, including those described herein above and below, that will support and hold a powered hand-tool, which un-checked will induce torque to the operator, and that by its strategically positioned joints counter any torque-induced rotation of the tool and thus avoid transfer of the torque to the operator.  
           [0009]    It is an additional object of an embodiment of the present invention to provide a device, including those described herein above and below, that controls the order and location of a series of operations using the hand-tool through feed-back to the operator if an operation is in the wrong location or out of order.  
           [0010]    It is a further object of an embodiment of the present invention to provide a device, including those described herein above and below, that with a plurality of optical encoder devices, which measure and communicate the angular position of the encoder device, the devices being placed at locations along an articulated arm holding a hand-tool provide the means to establish the position of the hand-tool relative to a selectable datum position.  
           [0011]    It is an additional object of an embodiment of the present invention to provide a device, including those described herein above and below that allows electrical connection to digital-to-analog converter for signal conversion to a scaled voltage signal, which is then communicated to a controlling means that can calculate and establish the position in a three-dimensional workspace.  
           [0012]    It is a further object of an embodiment of the present invention to provide a device, including those described herein above and below, that is capable of alerting the operator and even electrically latching the tool on the mounting arm by turning it off should the operator attempt to install a fastener in a wrong place or at a wrong time in a programmed order sequence.  
           [0013]    It is an additional object of an embodiment of the present invention to provide a device, including those described herein above and below, that provides a weight balancing means with a pneumatic cylinder connected to the articulated arm, wherein the pressure is adjustable to compensate for varying tool weights and operator preferences.  
           [0014]    An embodiment of this invention is a hand-tool support apparatus adapted to support the hand-tool and allow an operator to move the hand-tool to a multiplicity of chosen locations in a three-dimensional space. The apparatus includes a multi-component articulating arm, including a length with a proximal end adapted to be structurally attached to an external support, a distal end adapted to be detachably attached to the hand-tool, and a plurality of sections, each section capable of moving in a separate direction relative to an other section, wherein the arm is capable of allowing the operator to move the hand-tool to any of the chosen locations in the space. The apparatus further includes at least three positional feedback means, each capable of communicating a position of the positional feedback means, the positional feedback means being located at separated positions along the length of the arm, each position chosen to allow measurement of a position of a section of the arm relative to another section of the arm, such that a combination of the positions defines a selectable datum position of the hand-tool. The three positional feedback means are adapted to be connected to an electrical controlling means to receive the angular positions of the positional feedback means and correlate the positions.  
           [0015]    The following are preferred embodiments that may be included in any other embodiment. It is preferred that there be three positional feedback means and at least one of the three positional feedback means be an optical encoder to digitally measure a position of a component of the arm. It is further preferred that all of positional feedback means be optical encoders. It is also preferred that the controlling means further include an apparatus chosen from the group consisting of a computer, a dedicated control board, and an industrial programmable logic controller and said apparatus is capable of receiving signals from said positional feedback means and processing the signals through a conventional program to compute the angular position of each positional feedback means relative to a predefined datum, or start point, thereby establishing a position in the space. It is further preferred that the controlling means further include means to electrically and pneumatically control the distal end of the arm, said control being established by means of a user-defined set of programmable parameters, and display means to graphically instruct the user for tool set-up and in-process parameters feedback during tool use. It is also preferred that the apparatus further include latching means to electrically lock the tool upon receiving a signal from the controlling means that the position of the hand-tool is in an incorrect position in the space. It is further preferred that the hand-tool be a power hand-tool capable of transmitting a torque-induced rotation to the operator and the arm further include a first guiding means allowing a proximal section of the arm to articulate only in a single first direction, a second guiding means allowing a second section of the arm coupled to the proximal section to articulate only in a single second direction normal with first direction, and a third guiding means allowing the distal end of the arm to articulate only in a single third direction at an angle with a plane or the first and second directions. It is also preferred that there be three positional feedback means and each of said means are positioned along the arm to measure a position of each of the three sections. It is further preferred that the apparatus further include a weight countering means to counter the weight of the arm and hand-tool, the means comprising a pneumatic cylinder comprising clevis ends connected to proximal and distal ends of a section of the arm moving in a vertical direction, whereas the pneumatic cylinder is adapted to be fluid connectable to a pressurized fluid source. It is also preferred that apparatus further include pressure adjustment means in the pneumatic cylinder allowing adjustment of the pressure in the cylinder to compensate for varying tool weights and operator preference. It is further preferred that apparatus further include a tool mounting device comprising a primary V-block member rigidly attached to the distal end of the arm, a detachable opposing V-block, and clamping means comprising threaded fasteners to attach the detachable V-block to the primary V-block and exert clamping pressure on the detachable V-block adapted to retain a hand-tool between the V-blocks. It is also preferred that the third guiding means include a plurality of rotateably mounted support members in a vertically disposed parallelogram alignment allowing the distal end of the arm to articulate only in a vertical direction. It is further preferred that the arm include a first arm section comprising a proximal end rotateably connected to a mounting means adapted to be connectable to the external support and distal end to which is rotateably connected to a proximal end of a second arm section comprising a distal end attached to connection means connecting to a tool mounting means to detachably hold the hand-tool. It is also preferred that the arm further include at least one linear telescoping guide rod section that does not protrude behind a proximal end of the section when fully retracted and maintain the distal end in linear orientation throughout its movement. It is further preferred that the third section of the arm include a pair of the linear telescoping guide rods rigidly attached at the distal end of the second section of the arm in a vertically aligned parallelogram arrangement to maintain the distal end of the arm in a vertical orientation throughout movement in a vertical axis. It is also preferred that apparatus further include a weight countering means to counter the weight of the arm and the hand-tool, the means including a pneumatic cylinder comprising clevis ends connected to proximal and distal ends of a section of the arm moving in a vertical plane, whereas the pneumatic cylinder is adapted to be fluid connectable to a pressurized fluid source. It is further preferred that each of the positional feedback means be further adapted to be electrically connected to separate digital-to-analog converter modules for signal conversion to a scaled voltage, said voltage signal then communicated to said controlling means. It is also preferred that the controlling means further include an apparatus chosen from the group consisting of a computer, a dedicated control board, and an industrial programmable logic controller and said apparatus is capable of receiving said signals from said converter modules and processing the signals through a conventional program to compute the angular position of each three positional feedback means relative to a predefined datum, or start point, thereby establishing a position in the space. It is further preferred that the controlling means further include means to electrically and pneumatically control the distal end of the arm, said control being established by means of a user-defined set of programmable parameters, and display means to graphically instruct the user for tool set-up and in-process parameters feedback during tool use.  
           [0016]    A second embodiment of the invention is a power hand-tool support apparatus adapted to support the hand-tool and allow an operator to move the hand-tool to a multiplicity of chosen locations in a three-dimensional space. The apparatus includes a multi-component articulating arm that includes a length with a proximal end adapted to be structurally attached to an external support, a distal end adapted to be detachably attached to the hand-tool, and a plurality of sections, each section capable of moving in a separate direction relative to an other section, wherein the arm is capable of allowing the operator to move the hand-tool to any of the chosen locations in the space. As the power hand-tool is capable of transmitting a torque-induced rotation to the operator and the arm further includes a first guiding means allowing a proximal section of the arm to articulate only in a single first direction, a second guiding means allowing a second section of the arm coupled to the proximal section to articulate only in a single second direction normal with first direction, and a third guiding means allowing the distal end of the arm to articulate only in a single third direction at an angle with a plane or the first and second directions. The apparatus further includes at least three positional feedback means, each capable of communicating a position of the positional feedback means, the positional feedback means being located at separated positions along the length of the arm, each position chosen to allow measurement of a position of a section of the arm relative to another section of the arm, such that a combination of the positions defines a selectable datum position of the hand-tool. At least one of the three positional feedback means is an optical encoder to digitally measure a position of a section of the arm and the positional feedback means are adapted to be connected to an electrical controlling means to receive the angular positions of the encoder means and record the positions.  
           [0017]    A third embodiment of the invention is power hand-tool support apparatus adapted to support the hand-tool that is capable of transmitting a torque-induced rotation to the operator, the apparatus comprising a multi-component articulating arm capable of allowing the operator to move the hand-tool to the locations in a work space. The arm includes a length with a proximal end adapted to be structurally attached to an external support and a distal end adapted to be detachably attached to the hand-tool, and at least one linear telescoping guide rod section that does not protrude behind a proximal end of the section when fully retracted and maintain the distal end in linear orientation throughout its movement. It is preferred that a third section of the arm include a pair of the linear telescoping guide rods rigidly attached at a distal end of a second section of the arm, the rods in a vertically aligned parallelogram arrangement to maintain a distal end of the arm in a vertical orientation throughout movement in a vertical axis. It further preferred that the apparatus further include a weight countering means to vertically counter the weight of the arm and the hand-tool, the means comprising a pneumatic cylinder comprising clevis ends connected to proximal and distal ends of the third section of the arm moving in a vertical plane, whereas the pneumatic cylinder is adapted to be fluid connectable to a pressurized fluid source. It is also preferred that the arm further include a first guiding means allowing the arm to articulate only in a single first direction and the second guiding means allowing the arm to articulate only in a single second direction in a plane with first direction.  
           [0018]    A fourth embodiment of the invention is power hand-tool support apparatus adapted to support the hand-tool that is capable of transmitting a torque-induced rotation to the operator. The apparatus includes a multi-component articulating arm capable of allowing the operator to move the hand-tool to the locations in a work-space. The arm includes a length with a proximal end adapted to be structurally attached to an external support and a distal end adapted to be detachably attached to the hand-tool, and a first guiding means proximate the proximal end connecting to and allowing a first section of the arm to move only in a horizontal arc, a second guiding means connecting a proximal end of a second section of the arm to a distal end of the first section of the arm and allowing the second section of the arm to move only in a second horizontal arc relative to the distal end of the first section and in a plane with the first horizontal arc, and a third guiding means allowing the distal end of the arm to move only in a vertical line relative to a distal end of the second section.  
           [0019]    A fifth embodiment of the invention is a power hand-tool support apparatus adapted to support the hand-tool that is capable of transmitting a torque-induced rotation to the operator. The apparatus includes a multi-component articulating arm capable of allowing the operator to move the hand-tool to the locations in a work space. The arm includes a length with a proximal end adapted to be structurally attached to an external support and a distal end adapted to be detachably attached to the hand-tool, and a first guiding means proximate the proximal end of the arm connecting to a proximal end of a horizontally disposed first section of the arm and allowing the first section to move only in a horizontal arc, a second guiding means integral with the first section of the arm allowing a distal end of the first section of the arm to move only in a straight line normal to the proximal end of the first section and in a plane with the horizontal arc, a vertically disposed second section of the arm comprising a proximal end rigidly connected to the distal end to the first section and a free end being the distal end of the arm, and a third guiding means integral with the second section of the arm allowing the distal end of the arm to move only in a vertical line.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0020]    [0020]FIG. 1 is a front right side perspective view of an apparatus of the present invention.  
         [0021]    [0021]FIG. 2 is a top elevational view of said apparatus.  
         [0022]    [0022]FIG. 3 is a diagram of an electronic control system for an optical encoder device in said apparatus.  
         [0023]    [0023]FIG. 4 is a front right side perspective view of a tool holder the may be used on said apparatus.  
         [0024]    [0024]FIG. 5 is a front right side perspective view of a second tool holder the may be used on said apparatus.  
         [0025]    [0025]FIG. 6 is a left side elevational view of a second embodiment apparatus of the present invention.  
         [0026]    [0026]FIG. 7 is a top elevational view of said apparatus.  
         [0027]    [0027]FIG. 8 is front elevational view of said apparatus as well as the apparatus pictured in FIGS. 9 &amp; 10, although all the part numbers do not correspond with those for the apparatus of FIGS. 9 &amp; 10.  
         [0028]    [0028]FIG. 9 is a left side elevational view of a third embodiment apparatus of the present invention.  
         [0029]    [0029]FIG. 10 is a top elevational view of said apparatus.  
     
    
     DESCRIPTION OF PREFERRED EMBODIMENTS  
       [0030]    A apparatus is provided for use in industrial applications where a heavy tool such as an electric screwdriver or pop-riveting gun will be used by a person in an assembly operation. The apparatus combines the function of a standard tool balancing arm used throughout the industry with the ability to monitor its position in three-dimensional space with the use of optical encoders at revolute joints on each axis of movement on the arm. This positional feedback is then transmitted to either: a) the customer&#39;s logic controller, or b) to an integral control unit. In either case, the specific parameters required for the application can be set up for monitoring such attributes as point-to-point sequence and location, part tracking, and individual point failure (i.e. screw-driving torque fault). In one embodiment, the apparatus is constructed of high-strength aluminum structural elements anodized for anti-corrosion and aesthetics. Pivot points contain hardened steel bushings and Nylatron washers for smooth articulation and wear reduction. The pivot shafts must be fixed to one arm and floating in the mating arm for accurate position sensing, so press-fit pull dowels that have a pre-machine locating flat are used. The pneumatic assist is a standard stainless steel cylinder with an adjustable pressure regulator that controls the mount of lift on the arm based on tooling weight and operator preference. The rotary optical encoder is housed in aluminum and features a positive finger-latching connector and has a maximum resolution of 4096 pulses per revolution. The encoder&#39;s A/B quadrature output is then converted to analog voltage proportional to encoder position using a digital to analog converter. Because the position feedback tool balancer offers a unique output analog voltage for any point in its range of motion, users can set up parameters that can dictate such things as tightening sequences on bolt patterns or the ability to trace a torque failure to a specific screw in a sequence. End of arm mounting depth (i.e. screw-driving operation) can also be tracked to within roughly 0.030 inch accuracy. In a first embodiment, specific software would need to be provided to the user based on their logic controller and HMI application. This software would initially be developed based on the most commonly used and HMI&#39;s controllers and could be provided on disc or downloadable through a website. Custom applications could be developed for areas such as nonstandard controller/HMI software configurations and end effector tooling design. In a second embodiment, the encoder feedback would communicate directly with a dedicated control unit, consisting of a custom circuit board controller and a flat panel keypad/display, both housed in a NEMA enclosure. From this unit, all point-to-point parameters would be entered and stored for the application. All attribute verification would be made by this controller independent of any external control source. Such a device could communicate to external machine controllers by way of low voltage discrete signals, or via RS232 serial communication, depending on the user&#39;s preference. Once specific locations are “taught”, the user can the assign an identification to each location, assign overall or point specific tolerances to that location, and thus control the end effector tooling based on its location. A specific example would be an application where an operator is installing multiple screws with variable torque readings based on differing materials, screw length, etc. This tracking ability would enable the user to correspond specific torque readings to a given screw based on its location.  
         [0031]    Apparatus  10 , as shown in FIGS. 1 &amp; 2, is a power hand-tool support apparatus adapted to support the power driven hand-tool at distal end  11  and allow an operator to move the hand-tool to a multiplicity of chosen locations in a three-dimensional space, the hand-tool being capable of transmitting a torque-induced rotation to the operator when the hand-tool is used at the chosen locations. Apparatus  10 , being in the main an articulated arm constructed of case aluminum unless otherwise noted, is structurally attached at proximal end  13  to an external support such as wall, workbench, or work site frame with common fasteners through holes  16  extending horizontally through vertical base plate  14  of U-shaped pivot block  12 . Aligned hidden holes  17  extend vertically through upper horizontal flange  18  and lower horizontal flange  20 , both flanges being integral to and extend outwardly from base plate  14  of block  12 . First swing arm section  24  swings freely horizontally and is connected to block  12  by pivot shaft  22  secured by hidden press fit bushings at both ends and engaged through holes  17  and hidden vertical hole  28  that extends through proximal end  26  of section  24  from proximal top edge  30  through section  24  to proximal lower edge  32 . Distal end  34  of section  24  swings freely horizontally and is connected to the balance of the articulated arm by vertically aligned pivot shaft  36  which and extends through vertically aligned hidden hole  38  through distal end  34  opening outwardly through distal top edge  30 ′ and distal lower edge  32 ′ of section  24 . The prime (′) and double prime (″) designations on an identifying number indicates that area or part is similar to a previously designated and identified area or part or merely a different point of the same_part area. Vertically aligned shaft  36  is secured by hidden press fit bushings at both ends to pivot connector block  40  by engaging its ends through hidden hole  46  extending vertically through horizontal lower flange  42  and vertically aligned hidden hole  46 ′ extending vertically through horizontal upper flange  44 , both flanges being integral with and extending proximally from body  48  of block  40 . Vertical slot  50  opens distally from top to bottom of body  48  to receive proximal end  60  of lower second arm section  52  and proximal end  64  of upper second arm section  54 , both arm sections swinging freely vertically in the connection. Ends  60  and  64  have hidden horizontal holes  68  which receive lower pivot shaft  74  and hidden upper pivot shaft  74 ′ respectively, the shafts being secured to body  48  by lower press fit bushing  76  and hidden upper press fit bushing  76 ′ and by extending though lower hole  70  and median hole  70 ′, respectively, these hidden holes extending horizontally from side to side through body  48  and opening through slot  50 . Hole  70  and connection with end  60  is located proximate a lower edge of body  48  and hole  70 ′ and connection with end  64  is located at a median position vertically through body  48 . Vertical slot  58  opens proximally from top to bottom of the body of distal end tooling connection block  56  to receive distal end  62  of lower second arm section  52  and distal end  66  of upper second arm section  54 , both arm sections swinging freely vertically in the connection to block  56 . Ends  62  and  66  have hidden horizontal holes  68 ′ which receive lower pivot shaft  78  and upper pivot shaft  78 ′ respectively, the shafts being secured to block  56  by lower press fit bushing  80  and upper press fit bushing  80 ′ and by extending though lower hole  72  and upper hole  72 ′, respectively, these hidden holes extending horizontally from side to side through block  56  and opening through slot  58 . Hole  72  and connection with end  62  is located proximate a lower edge of block  56  and hole  72 ′ and connection with end  66  is located at an upper edge of block  56 . The vertical distances between holes  70  and  70 ′ and holes  72  and  72 ′ equal to maintain arm sections  52  and  54  in a parallelogram relationship as they swing vertically to maintain block  56  and any tool attached thereto in a vertical alignment relative to pivot block  12 . A plurality of threaded horizontal holes extends from distal end  11  into block  56  to provide secure attachment means of a standard tool holding device. Vertical flange  82  is integral with and extends upwardly from upper edge  83  of end  66  with hidden horizontal hole  84  extending through the flange to receive clevis pin  92  that rotates freely in hole  84 . Pin  92  extends into hole  90  through clevis member  88  of pneumatic cylinder  86  connecting pneumatic piston extension member  94  to the distal end of the second section of the articulated arm. Hidden horizontal hole  100  is cut from side to side of body  48  opening through slot  50  proximate an upper distal corner to receive clevis pin  96  which engages a hidden hole in pneumatic piston cylinder member  95  for a freely swinging connection. Nipple  98  provides access connection from cylinder  86  to a pneumatic fluid source. Optical encoder device  102  is mounted on the top surface of flange  18  with the optical scanner connected to the top end of shaft  22  to measure the radial angle position of section  24  in a horizontal plane. Optical encoder device  106  is mounted on the top surface of horizontally swinging flange  44  to measure the radial angle position of the flange in a horizontal plane providing an optical direction to fix the x-y horizontal position of distal end  11  and thus the hand-tool. Optical encoder device  110  is mounted on the side surface of body  48  with the optical scanner connected to the end of upper pivot shaft  74 ′ to measure the radial angle position of section  54  in a vertical plane providing an optical direction to fix the z-axis vertical position of distal end  11  and thus the hand-tool. The optical encoder devices are each part number ESM-1024-375 from US Digital Corporation of Vancouver, Wash., USA, connected through cables  104 ,  108 , and  112 , respectively, to separate digital-to analog converter modules, the cables being part number CA-3620-6FT. Encoder  102  is connected through cable  104  to digital to analog converter module  114 , which is part number EDAC-R also from US Digital Corporation, and thence to a computer, a dedicated control board, or an industrial programmable logic controller, all state of the art systems, as shown in the diagram of FIG. 3. Encoders  106  and  110  are each connected in the same fashion as shown on FIG. 3. The switch number designations on module  114  are (1) quad multiplier-on, (2) UP count direction-off, (3) index-no reset, and (4) analog-0-10V on. The encoder pinout is 1-ground, 2-index, 3-A channel, 4-±5 VDC power, and 5-B channel. The analog pinout is 1-ground and 2-output voltage. It is well within ordinary skill in the art with said systems to be capable of receiving said digital signals from said converter modules and processing the signals through a conventional analog program to compute the angular position of each encoder relative to a predefined datum, or start point, thereby establishing a position in the work_space.  
         [0032]    Tool holder mounting devices  79  and  82  are shown in FIGS. 4 and 5. Vertical connection plate  85  of V-block mount  79  is fastened through holes to block  56  at distal end  56  holding fixed V-block  87  horizontally. Free V-block  89  is attached by fasteners through holes  93  into block  87  forming diamond shaped hole  92 . The hand tool is positioned in hole  92  and block  89  is tightened to secure the tool in hole  92 . Split-ring mount  81  is attached through plate  85 ′ positioning fixed split-ring block  95  horizontally. The hand-tool base is inserted in circular hole  97  and the distal end of the block is pulled to close vertical slot  99  which extends horizontal from one edge through the block, through hole  97  and into the block on the other side of the hole toward but not to the opposite edge of the block to secure the tool in the mount.  
         [0033]    Apparatus  120 , as shown in FIGS. 6, 7, and  8 , is a power hand-tool support apparatus similar to apparatus  10  adapted to support the power driven hand-tool at distal end  11 ′ with improved resistance to transmitting a torque-induced rotation to the operator. Pivot block  12 ′ and first swing arm section  24 ′ and the connections at the proximal and distal ends of section  24 ′ are identical to those of apparatus  10 . Second swing arm section  122  has an integral clevis bracket  124  to connect with the distal end of section  24 ′ and integral housing section  126  open at the bottom to receive a pair of vertically aligned parallel telescoping rods  128  that constitute a third section of the articulated rod. Rods  128  are made to close fitting tolerances between the sliding sleeves to reduce any play in the x-y axis. Fixed between the distal ends of rods  128  is horizontal tool holding platform b with tool holding vertical opening  134  through a central portion of the platform. Horizontal control handles  132  are fixed to lateral edges of platform  130  to allow easy tool movement and positioning. The movement axes of the arm are designated with axis lines  136  and  138  and the z-axis with arrows  140 .  
         [0034]    Apparatus  142 , as shown in FIGS. 9, 10, and  8 , is a power hand-tool support apparatus similar to apparatus  10  and  120  adapted to support the power driven hand-tool at distal end  11 ″ with improved resistance to transmitting a torque-induced rotation to the operator. Pivot block  12 ″ and the connection to proximal end section  144  of the first section of the rod are identical to those of apparatus  10 . The first section of the rod is constructed of vertically aligned horizontal parallel telescoping rods  146  and  148  with the proximal ends rigidly attached to end section  144  and the distal ends rigidly attached to housing section  126 ′ open at the bottom to receive a pair of vertically aligned parallel telescoping rods  128 ′ that constitute a third section of the articulated rod. The third section is essentially identical to that of apparatus  120  and FIG. 8 shows that view with prime designations added to the numbers. The movement axes of the arm are designated with axis line  136 ′ and with arrows  138 ′ and  140 ′.  
         [0035]    Positional feedback devices are preferably commercially available optical encoder devices that provide a digital signal of a radial angle position. However for other arm constructions other satisfactory positional feedback devices include commercially available string pot transducers, resolvers that count pulses on a disc, scaled voltage devices, such as linear vector transducers, known as LVDT, and like performing devices. String pot transducers, for example, may be used in the devices shown in FIGS. 7 through 10 positioned between telescoping rods  128  or  128 ′ with the string extending from the pot on the section  122  down to and connected to platform  130 . Likewise a hydraulic cylinder to assist lifting vertically may be positioned vertically between rods  128  or  128 ′ with the ends connected between the lower surface of section  122  platform  130  with an LVDT incorporated in the hydraulic cylinder to measure and signal the vertical position of the hand-tool.  
         [0036]    While this invention has been described with reference to specific embodiments disclosed herein, it is not confined to the details set forth and the patent is intended to include modifications and changes that may come within and extend from the following claims.