Abstract:
A mechanical firing adapter for an igniter, such as an M81, to enable remotely firing the igniter using a robot, such as a MTRS. MTRS are used in the disposal/disruption of IEDs. Igniters are generally used with a shock tube, a type of fuse that is used with explosive charges, like shape charges. The adapter has a base plate with a first area to secure the igniter, a second area to withdraw the igniter&#39;s pull-rod by the attached pull-ring, and a compound assembly that interfaces with a robot. The pull-ring is attached to a sled that moves rearward when a clinching force is applied to opposing paddles, which causes the connected angled articulating struts to spread open. The paddles are moved closer by a remote controlled robotic jaw, and this closing movement causes the sled to move rearward, pulling out the pull-rod, which sets off the explosive.

Description:
STATEMENT OF GOVERNMENT INTEREST 
     The invention described herein may be manufactured and used by or for the Government of the United States of America for Governmental purposes without the payment of any royalties thereon or therefore. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates generally to explosive tools and more particularly to a means of remotely initiating an M81 shock tube igniter. 
     2. Background 
     An M81 igniter is used to ignite a time blasting fuse or to initiate a shock tube. Shock tube is a thin plastic tube with a thin layer of special explosive material deposited on its interior surface. The standard M81 igniter has the following visible components: a small plastic tube with a pull-ring on a pull-rod projecting from one end, a safety (cotter) pin that passes through the tube, and a screw cap that secures a holding mechanism for the fuse or shock tube. The igniter can accommodate a shock tube or a time blasting fuse. A two-piece plastic plug allows proper securing of the shock tube (with just inner piece removed) or the time blasting fuse (with both pieces removed). A partially cut away prior art view of an M81 is shown in  FIG. 6 . 
     The M81 was engineered to be manually actuated by the operator. The ignition sequence is typically as follows: An operator (explosive expert) while positioning an explosive charge at the desired distance from the target, begins dispenses shock tube/time blasting fuse from the dispenser. After the explosive charge has been positioned, the operator moves away, continuing to dispense the shock tube/time blasting fuse until a sufficient pay-out length has been deployed to reach a safe area for personnel. The shock tube is then connected to the igniter. To make this connection the operator loosens the screw cap and removes some or all of the inner piece of the two-piece plastic plug, cuts off an end of the tube/fuse and inserts it in the hole from which the plug was removed. The screw cap is then re-tightened to secure the fuse or shock tube. The safety (cotter) pin can then be removed. To initiate the M81, while holding the body of the M81, the operator uses his other hand to pull on the pull-ring, which in turn pulls out the pull-rod. The pull-rod pulls the firing-pin against the force of a spring. When the limit of travel is reached, the pull-rod releases the firing-pin, which is forced by the spring into the primer, which fires with a flame and an explosive shock which ignites the fuse or initiates the shock tube, therein detonating the explosive charge. 
     In more recent developments, the shock tube can be manually initiated using an electrical spark produced by a sparking device attached to a robotic device. In both cases (M81 and sparking device) manual ignition is required. An example of the robotic device is the MTRS platform (Man Transportable Robotic System). Initiating shock tube by hand requires the robot operator to maneuver the robot from the target site, dispense a sufficient pay-out length until enough has been deployed for the operator to move away, while continuing the dispensing shock tube, to a safe area. This method of operation is time consuming and prevents additional investigation once the shock tube deployment begins. Another method of initiating shock tube is by an electrical spark produced by a firing device attached to the MTRS robotic platform. This method requires tethering the robot to the shock tube. The tethering prevents free movement of the robot, and is problematic. For instance, if a robot runs over the shock tube, the shock tube can become tangled in the drive tracks of the robot, limiting the robot&#39;s movement. 
     SUMMARY OF THE INVENTION 
     The disclosed invention, in one aspect, is a mechanical firing adapter for an igniter, such as M81 and M60, where the firing adapter enables the igniter to be actuated by an MTRS (Man Transportable Robotic Systems), where the MTRS is generally remotely controlled. 
     An igniter with the disclosed mechanical firing adapter enables a robotic arm to effect movement that simulates manual activation of legacy igniters. The robot can and usually is remotely controlled. Taken together, the invention therein is also a method to activate, remotely, an igniter fitted with the invented adapter. In another aspect, the invention uses a Man Transportable Robotic System (MTRS) platforms, which are relatively less expensive systems. The mechanical firing adapter enables the remote controlled robot to not only deploy an explosive charge to an incident site, where the incident site is where the charge is detonated, but the igniter and shock tube can also be deployed by using the MTRS. The operator is positioned at a safe distance, and the robot can maneuver freely until the explosive has been set up and conditions are ready to fire the explosive charge. The robot&#39;s distance to a safe location is significantly closer to the incident site than what is consider acceptably safe for personnel. 
     The mechanical firing adapter, in another aspect, includes a base plate with a first area with a frame for fastening the igniter to a front-side of the base plate; a second area for withdrawing the pull-rod axially from the igniter, where upon being withdrawn to a limit of travel, the igniter is activated. The second area generally includes a plurality of elongate slots, where each elongate slot has a length that is at least as long as the limit of travel. A compound assembly completes the interface between the robot and the igniter. Robots typically have an arm with a clamping jaw with a closing action for picking up items. When the jaw is closed the compound assembly converts the closing action into a substantially linear movement that is orthogonal to the closing action. The linear movement causes a controlled withdrawal of the pull-rod from the igniter. 
     The compound assembly includes a sled element that can linearly move across the base plate tracking along a medial line. The sled element has a medial hitch onto which the pull-ring can be attached, and the elongate slots serve as a tracking mechanism for the sled element to connect to the base plate. The compound assembly includes a pair of opposing paddles conformed to be simultaneously held and brought towards each other when the robotic jaw closes. Each of the pair of opposing paddles is attached to at least two articulating struts, at least one to the front and at least one to the rear, such that the front and rear struts are angled with respect to each, and when the angle between struts is small the distance between opposing paddles is much larger than when the angle is larger. As will be shown, a relatively small decrease in the distance between opposing paddles produces a significant opening of the angle and spreading of the front and rear struts. 
     The movement of the struts is possible, because each strut is pivotal on both ends, and at least one front articulating strut is pivotally attached to a front pivotal pin on the paddle, and the strut extends forward to a front pin on the first area of the base plate. At least one rear articulating strut is pivotally attached to a rear pin on the paddle and the rear strut extends rearward to a sled pin. 
     When a clinching force is applied by the robotic jaw, such as by a pair of opposing surfaces on hydraulic pistons or motorized geared jaws, the pair of opposing paddles move toward each other causing the articulating elements to spread, therein forcing the sled element, which as previously described is connected to the rear struts with rear pivotal pins, to move toward the rear. The pull-ring is jointly attached to the sled&#39;s medial hitch and the pull-rod, movement of the sled to the rear withdraws the pull-rod, quickly reaching the limit of travel. Accordingly, the pull-rod releases the firing pin, which is forced by the spring into the primer. The primer fires with a flame and an explosive shock, that will ignite an attached fuse or an attached shock tube. 
     In another aspect, the invention is a method to activate, remotely, an igniter mounted on the invented adapter. The method may include using the MTRS to place an explosive charge and dispense the shock tube from a dispenser; setting down the dispenser down; and using the MTRS to perform other functions; paying out additional shock tube if required; and using the MTRS to robotically initiate the shock tube. 
     Among other advantages, the mechanical firing adapter for an M81 device provides a means of mechanically initiating an M81 shock tube igniter remotely with the Man Transportable Robotic System (MTRS) platforms. This configuration allows an operator to deploy a robot to an incident site, and both the operator and robot may maneuver freely until it is time to fire the explosive charge. The robot may be moved to a safe location, where the robot may use the adapter to initiate, mechanically, the shock tube initiation system. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The foregoing invention will become readily apparent by referring to the following detailed description and the appended drawings in which: 
         FIG. 1  is an elevation perspective view of an exemplary embodiment of the invented mechanical firing adapter for an igniter, as exemplified by an M81 device, wherein the drawing, taken with  FIG. 2  and  FIG. 3 , illustrates that a relatively small movement by the paddles toward each other creates enough linear translational movement of the sled element to pull the pull-rod far enough out to activate the igniter; 
         FIG. 2  is an elevational perspective view of the exemplary embodiment shown in  FIG. 1 , wherein the paddles have been moved closer together; 
         FIG. 3  is a diagrammatic comparison of movement of each paddle and the sled element, where, in the illustrated embodiment, the sled element moves about twice as far as the movement by a single paddle; 
         FIG. 4  is an elevation perspective view of another exemplary embodiment of the invented mechanical firing adapter for an igniter, as exemplified by an M81 device, wherein the articulating elements are paired, producing twice as many articulating elements with much improved torsional resistance, and a much more complex sled element; 
         FIG. 5   a  is a substantially planar view of a robotic arm with a clamping jaw, wherein the jaw is open; 
         FIG. 5   b  is a substantially planar view of the clamping jaw shown in  FIG. 5   a , where the pistons have been actuated, causing the gap between the jaws to be significantly reduced; and 
         FIG. 6  is a substantially cut-away planar view of an igniter such as M60 or M81, wherein the igniter has a body with a primer end with a firing-pin, a primer, a spring, and an opposing end having a safety cotter pin, pull-rod with an attached pull-ring. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The mechanical firing adapter provides the compatibility of using a robotic arm to utilize legacy igniters, such as a M81, where generally the igniter is in communication with an explosive charge via a shock tube that is connected on one end to the igniter and on a distal end of the shock tube is connected to the explosive charge. The legacy igniter is defined herein to mean that it was originally engineered for manual activation. The compatibility eliminates the need for manual activation of the igniter, and this feature enables the use of a shorter length of shock tube with less exposure of personnel to a potentially dangerous target area/incident site. The invented mechanical firing adapter provides a mechanism for using remotely controlled robots to conduct, effectively, a nominally manual operation robotically. The net effect is the continued use of the igniter, like the M81, thus extending the useful life of a stock piled standard item, preventing its obsolescence, and providing Man Transportable Robotic System (MTRS) platforms with a new tool for other possible applications. The invention is also a method to activate, remotely, an igniter fitted with the invented adapter, and in so doing reduce the chance of a robot&#39;s tracks and other components to be snarled by the shock tube. 
     As shown in  FIG. 6 , the legacy igniter  81  has a body  83  with a primer end  85  with a firing-pin  87 , a primer  89 , a spring  91 , and an opposing end  93  having a pull-rod  95  with an attached safety cotter pin  97 , a pull-ring  99  and a limit of travel  101  as shown in  FIG. 2 . 
     Referring to  FIG. 1 , the firing adapter  10  includes: a base plate  20  having a front edge  22 , a front-side  24 , a back-side  26  (See  FIG. 4 ), a perimeter edge  28 , and a rear edge  30 . The legacy igniter  81  is not an element of the invention, and as such it is shown with dashed lines. The illustrated base plate  20  is substantially rectangular, but other shapes are anticipated. For instance, a round base plate would provide improved lateral stability. The base plate could also have legs, and more than one layer. 
     The mechanical firing adapter  10  has a first area  12 . Included in the first area  12  is a frame  14 , functionally dimensioned to secure the igniter  81  on the front-side  24  of the base plate  20 . The front side  24  of the base plate  20  has eyelets  32  through which a cable strap  34  is cinched around the igniter&#39;s body  83 , further securing the igniter  81  in the frame  14 . A second area  16  of the plate  20  is used to withdraw the pull-rod  95  axially from the igniter&#39;s body  83 , where upon being retracted a distance that is the limit of travel  101  (as shown in  FIG. 2 ), the igniter  81  is activated. The second area  16  includes a plurality of elongate slots  40 , which are apertures extending through the base plate, where each elongate slot has a length that is at least as long as the distance of the limit of travel. The illustrated slots include a medial first slot  42 , where the medial first slot extends lengthwise, aligned coplanar with the pull-rod. Additionally, there is a lateral second slot  44  and a lateral third slot  46 . The lateral slots  44 , 46  are substantially parallel to the medial slot  42 . The medial slot substantially bisects the lateral slots  44 , 46 . Cumulatively, the elongate slots serve as a tracking mechanism for the sled element to connect to the base plate. 
     The firing adapter  10  has a compound assembly  58  that when clinched converts a closing action into a linear movement that is a substantially orthogonal to the closing action. The linear movement produces a controlled withdrawal of the pull-rod from the igniter. The compound assembly includes a sled element  50  that may be linearly moved across the base plate  20 , tracking along the medial first slot  42 . The sled element  50  has a medial hitch  52  onto which the pull-ring can be attached. There are a pair of opposing paddles  60  conformed to be held and clinched by a single robotic jaw (not show), where a first paddle  60   1  is attached to at least two articulating first struts  70   1 , 70   2 . Each first strut is pivotal on both ends, and at least one front articulating first strut  70   1  is pivotally attached to a first front pin  80   1  of the first paddle  60   1  and extends to the first area of the base plate where it is pivotally attached to a first block pin  14   1 . The first block pin  14   1  projects substantially perpendicular from the base plate and is located proximate to a primer end  85  (see  FIG. 6 ) of the frame  14 . At least one rear articulating first strut  70   2  is pivotally attached to a rear pin  80   2  of the first paddle  60   1  and extends to the second area of the base plate where it is pivotally attached to a first sled pin  50   1 . The first sled pin  50   1  projects substantially perpendicular from the sled  50  and is located approximately lateral to the medial hitch  52  and substantially over the lateral second slot  44 . A second paddle  60   2 , that is substantially a mirror of the first paddle  60   1 , is attached to at least two articulating second struts  72 . Each second strut  72  is pivotal on both ends, where at least one front articulating second strut  72   1  is pivotally attached to a front pin  82   1  of the second paddle  60   2  and extends to the first area  12  of the base plate where it is pivotally attached to an opposing first block pin  14   2 . The opposing first block pin  14   2  projects substantially perpendicular from the base plate  20  and it is located proximate to the other side of the primer end  85  of the frame  14 . There is at least one rear articulating second strut  72   2  pivotally attached to a rear pin  82   2  of the second paddle  60   2 . The strut  72   2  extends to the second area  16  of the base plate  20 , where it is pivotally attached to a second sled pin  50   2 . The second sled pin  50   2  projects substantially perpendicular from the sled  50  and it is located on the opposing side of the sled element, approximately lateral to the medial hitch  52  and substantially over the lateral third slot  46 . 
     When a clinching force is applied by the jaw on the robotic arm, the pair of opposing paddles,  60   1  and  60   2 , move toward each other causing the articulating elements  70  to spread, therein forcing the sled element to move away from the first area of the base plate toward the rear edge  30 . 
     The pull-ring, which is jointly attached to the sled&#39;s medial hitch and the pull-rod, withdraws the pull-rod, quickly reaching the limit of travel  101  (as shown in  FIG. 2 ). On reaching the limit of travel, the pull-rod releases the firing pin  87  (see  FIG. 6 ), which is forced by the spring  91  into the primer  89 , which fires with a flame and an explosive shock that will ignite an attached fuse or an attached shock tube. 
     Referring to  FIG. 2 , which is an elevational perspective view of the exemplary embodiment shown in  FIG. 1 , wherein the paddles have been partially moved together, causing the rearward movement of the sled. In  FIG. 1 , each of the paddles are initially about 0.875 inches (P I ), as measured from an inner bottom edge of a paddle to a lateral edge of the base plate. In  FIG. 2  each of the paddles are closer, about ˜0.5 inches (P F ) as measured from an inner bottom edge of a paddle to a lateral edge of the base plate. The net movement of each paddle is about ˜0.375 inches closer to the lateral edge. In  FIG. 1 , the sled element, as measured from a rear edge of the sled element to a rear edge  30  of the base plate was initially about 1.685 inches (S I ); and in  FIG. 2  the distance to the rear edge is about 0.875 inches (S F ). The net change for each paddle is the absolute value |P F -P I | or (0.875-0.50), which is about 0.375 inches. The net change for the sled element is the absolute value |S F -S I | or (1.685-0.875), which is about ˜0.81 inches. So, the sled element moves about twice as far as a paddle. This configuration is shown in  FIG. 3 . The limit of travel  101  is, of course, sign sensitive, as the pull-rod has to be withdrawn a finite distance, or else the firing pin will not be released, hence the use of the absolute brackets. As is evident from  FIG. 2 , there is still at least another 0.875 inches left in reserve. If more travel is desired, the invented adapter may be scaled up, and the struts may be made even longer. The adapter is dimensioned according to the requirements of the task. 
     Referring to  FIG. 4 , which is an elevation perspective view of another exemplary embodiment of the invented mechanical firing adapter  10 ′ for an igniter. In the current illustrated embodiment, there are a plurality of paired articulating elements, which imparts much improved torsional resistance, and overall improved ruggedness. The compound assembly  58  has a sled  50  with a traveler  51 . The mechanical firing adapter is fitted with an igniter  81  having a body  83 . In the illustrated embodiment, the cotter safety pin  97  is still in place. The base plate has a front-side  24 , a back-side  26 , and a perimeter edge  28 . As before, the base plate has substantially two functional areas. There is a first area that includes framing elements  14   L ,  14   R ,  17   L  and  17   R , where framing elements  14   L ,  14   R  secure the primer end of the igniter (the primer end connects to the shock tube), and the opposing framing elements  17   L ,  17   R , which secure the opposing end of the igniter. In the illustrated embodiment, the eyelet  32  has a cinched cable tie  34  securing the body  83  of the igniter to the front-side  24  of the base plate  20 . Additionally, there are blocks  15   L , 15   R  which are lateral to the framing elements  14   L , 4   R , which in effect elevate and support the front bearing pins for some of the articulating struts. 
     There is a second area for withdrawing the pull-rod  95  axially from the igniter. As previously discussed, upon being withdrawn a distance that is a limit of travel, the igniter is activated. The second area includes a plurality of elongate slots  40 , which are apertures extending through the base plate. Each elongate slot has a length that is at least as long as the distance of the limit of travel. The illustrated elongate slots include a medial first slot  42  that extends lengthwise. It is substantially aligned coplanar with the pull-rod  95 . Also shown are a lateral second slot  44  and a lateral third slot  46 , where the lateral slots  44 , 46  are substantially parallel to the medial slot  42 . The medial slot  42  essentially bisects the lateral slots  44 ,  46 . 
     The mechanical firing adapter has a compound assembly  58  that when force is applied as shown in the direction indicated by the large black arrows labeled F, the force produces a closing action. This closing action is converted into a substantially orthogonal linear movement. The linear movement produces a controlled withdrawal of the pull-rod from the igniter&#39;s body. 
     The sled element  50 , pushed by the articulating struts, moves linearly across the base plate, tracking along the medial first slot  42 . The sled element  50  has a medial hitch  52  onto which the pull-ring can be attached. The assembly has a pair of opposing paddles  60 , where each paddle  60   1 , 60   2  is substantially lateral to the frame. Each paddle  60   1 , 60   2  has a vertical base  63   1 , 63   2  that enables a robotic arm with a hand or jaw to grasp and close the opposing paddles  60 .  FIG. 5   a  and  FIG. 5   b  illustrate a portion of a robotic arm with a clamping jaw. The pivoting articulating struts  70   1 , 71   1  and  70   2 , 71   2 , on the first paddle  60   1  has an outer front pin  81   1 , an inner front pin  80   1 , an outer rear pin  81   2  and an inner rear pin  80   2 . The inner pins  80   1  and  80   2  are barely visible, obscured by the vertical base  63   1 . The pairs of articulating first struts are substantially parallel. Each strut is pivotal on both ends. The pairs of articulating first struts include an outer front first strut  71   1 , an inner front first strut  70   1 , an outer rear first strut  71   2 , and an inner rear first strut  70   2 . The outer front first strut  71   1  extends from paddle pin  81   1  to the front of the base plate  20  where it is pivotally attached to a right block pin  15   1  protruding from a lateral right block  15   R . The right block pin  15   1  projects substantially perpendicular from the base plate  20 , and it located proximate to the front end of the frame. The inner front first strut  70   1  extends from paddle pin  80   1  to the front of the base plate where it is pivotally attached to a first bearing pin  14   1 . The first bearing pin  14   1  projects substantially perpendicular from the base plate and is located proximate to the right framing element  14   R . The outer rear first strut  71   2  extends rearward from paddle pin  81   2  to the second area of the base plate and is pivotally attached to a first traveler pin  51   1 . The traveler  51  is seated on the sled element  50 , and the first traveler pin  51   1  projects substantially perpendicular from the traveler  51 . Its position is substantially lateral to the medial hitch  52 , and substantially lateral to the lateral second slot  44 . The inner rear first strut  70   2  extends from paddle pin  80   2  to the second area of the base plate and is pivotally attached to a first sleeved bearing pin  50   1  that is seated in a first lateral aperture  53   R . The first lateral aperture  53   R  is substantially aligned with the lateral second slot  44 . 
     The second paddle  60   2  has an outer front second pin  83   1 , an inner front second pin  82   1 , an outer rear second pin  83   2  and an inner rear second pin  82   2  to which are attached two pairs of parallel articulating second struts, where each strut is pivotal on both ends. The pairs of articulating second struts includes an outer front second strut  73   1 , an inner front second strut  72   1 , an outer rear second strut  73   2 , and an inner rear second strut  72   2 . The outer front second strut  73   1  extends from paddle pin  83   1  to a left block pin  15   1  protruding from a lateral left block  15   L . The left block pin  15   1  projects substantially perpendicular from the base plate  20 , and it located proximate to the front end of the frame. The inner front second strut  72   1  extends from paddle pin  82   1  to the front of the base plate where it is pivotally attached to a second bearing pin  14   2 . The second bearing pin  14   2  projects substantially perpendicular from the base plate and is located proximate to framing element  14   L . The outer rear second strut  73   2  extends from paddle pin  83   2  to a second traveler pin  51   2 . The second traveler pin  51   2  is located substantially lateral to a rear of the medial hitch  52  and substantially lateral to the lateral third slot  46 . The inner rear second strut  72   2  extends from paddle pin  82   2  to the second area of the base plate, and it is pivotally attached to a second sleeved bearing pin  50   2  seated in a second lateral aperture  53   L . The second lateral aperture  53   L  is substantially aligned with the lateral third slot  46 . 
     Referring to  FIG. 5   a , this figure is a substantially planar view of an actuatable clamping jaw  100 . The clamping jaw  100  has a right plate element  102  seated on a first actuatable piston  106 , where the first actuatable piston  106  is mounted on one side  110  of the clamping jaw  100 . An opposing left plate element  104  is seated on a second actuatable piston  108  mounted on an opposing side  112  of the clamping jaw  100 , where both the first actuatable piston  106  and the second actuatable piston  108  are retracted. 
     Referring to  FIG. 5   b , the pistons  106 ,  108  have been actuated, and are fully extended, narrowing a gap  120  between the right plate element  102  and the opposing left plate element  104 . 
     The invention further includes a method of igniting an explosive charge. The method may include the steps of providing an explosive charge, a length of shock tube spooled on a dispenser, an igniter (such as M81) having a body with a primer end for attaching the shock tube and an opposing end having a pull-rod with an attached pull-ring, and a safety cotter pin, and a mechanical firing adapter to which can be fastened the igniter. The mechanical firing adapter has a base plate with a first area for securing the igniter, a second area including a sled element with a hitch to which the pull-ring can be fastened, and a compound assembly of opposing paddles connected to articulating struts. The struts convert a jaw-like closing motion of the paddles by a robotic arm into a translational linear movement of the sled element therein withdrawing the pull-rod. The method further includes attaching the shock tube to the igniter; and confirming the paddles are in the fully open position. The sled element is proximate to the first area. The method further includes attaching the igniter to the mechanical firing adapter; confirming by an inspection by a robot that an explosive charge may be moved close enough to the target to be effective, where during the inspection, the shock tube may be dispensed; setting up the explosive charge and connecting the shock tube to the explosive charge. The method further includes dispensing additional shock tube as needed; positioning the mechanical firing adapter such that the paddles are accessible and confirming that there is no clinching force on the paddles; confirming that a safety area is still clear; removing the safety pin; providing an additional safe region for any personnel; and closing the paddles utilizing a remote controlled robotic jaw, therein detonating the explosive charge. 
     Finally, any numerical parameters set forth in the specification and attached claims are approximations (for example, by using the term “about”) that may vary depending upon the desired properties sought to be obtained by the present invention. At the very least, and not as an attempt to limit the application of the doctrine of equivalents to the scope of the claims, each numerical parameter should at least be construed in light of the number of significant digits and by applying ordinary rounding.