Patent Publication Number: US-11029113-B2

Title: Trigger actuator

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is based upon and claims the benefit of priority to U.S. Provisional Application No. 62/804,982, filed Feb. 13, 2019, and hereby incorporated by reference in its entirety. 
    
    
     FIELD OF THE INVENTION 
     This invention relates to devices and methods for remotely pulling the trigger of a firearm. 
     BACKGROUND 
     It is a challenge for individuals with paralysis or limited upper extremity control to enjoy shooting sports. Accurate shooting requires a combination of gross and fine motor skills to acquire a target within the sights of a firearm, take careful aim and then squeeze the trigger without adversely affecting the aim point. Advantage may be had by individuals lacking the fine manual motor skills necessary for a controlled pull of the trigger by employing a remote trigger pulling mechanism which relies on machine actuation of the trigger using other muscle groups, such as the diaphragm, to control the machine actuation. 
     SUMMARY 
     The invention concerns a device for pulling a trigger of the firearm. In an example embodiment, the device comprises an actuator, a controller, and a switch. The actuator is mountable on the firearm adjacent to the trigger. The actuator has a body movable into engagement with the trigger for pulling the trigger. The body is moveable out of engagement with the trigger to permit the trigger to reset. The controller is in communication with the actuator. The controller is adapted to transmit a first command to the actuator for moving the body into engagement with the trigger for pulling the trigger, and a second command to the actuator for moving the body out of engagement with the trigger. The switch is in communication with the controller. The switch is adapted to transmit a first signal to the controller for causing the controller to transmit the first command to the actuator and a second signal to the controller for causing the controller to transmit the second command to the actuator. 
     In an example, the actuator comprises a servomotor and an arm. The servomotor has a rotatable shaft oriented transversely to a line of motion of the trigger. The arm is mounted on the shaft and extending transversely thereto. The arm has a free end engageable with the trigger upon rotation of the shaft. 
     As an example, the controller comprises a microprocessor. In an example, the switch comprises a pressure sensitive switch. In a particular example, the switch comprises a momentary switch. In another particular example, the switch comprises a push to close type switch. 
     In an example, the device further comprises a conduit in fluid communication with the pressure sensitive switch. The conduit is for conveying a change in gas pressure to the pressure sensitive switch. 
     In an example, the controller is adapted to transmit a third command to the actuator for moving the body into engagement with the trigger in preparation for pulling the trigger. 
     The invention also concerns a method for remotely pulling a trigger of a firearm using an actuator controlled by a controller. In an example embodiment, the method comprises:
         starting with the actuator in a reset position wherein the actuator does not engage the trigger;   transmitting a first signal to the controller for moving the actuator into a first position into engagement with the trigger, the controller thereby moving the actuator into the first position in response to the first signal;   transmitting a second signal to the controller for moving the actuator into a second position pulling the trigger;   measuring a time period between transmitting the first signal and the second signal;   if the time period is less than a threshold value, then the controller moves the actuator into the second position thereby pulling the trigger and then moves the actuator into the reset position in response to the second signal;   if the time period is greater than the threshold value then the controller moves the actuator into the reset position in response to the second signal.       

     An example of the method may include steps wherein the first signal is transmitted to the controller by closing a switch. As an example, the method may include the step wherein the second signal is transmitted to the controller by closing the switch a second time. An example of the method may include steps wherein the switch is closed in response to changing a gas pressure. 
     The invention further encompasses a firearm. In an example embodiment the firearm comprises a trigger, an actuator, a controller, and a switch. The actuator is mountable on the firearm adjacent to the trigger. The actuator has a body movable into engagement with the trigger for pulling the trigger. The body is moveable out of engagement with the trigger to permit the trigger to reset. The controller is in communication with the actuator. The controller is adapted to transmit a first command to the actuator for moving the body into engagement with the trigger for pulling the trigger, and a second command to the actuator for moving the body out of engagement with the trigger. The switch is in communication with the controller. The switch is adapted to transmit a first signal to the controller for causing the controller to transmit the first command to the actuator, and a second signal to the controller for causing the controller to transmit the second command to the actuator. 
     As an example, the actuator comprises a servomotor, an arm. The servomotor has a rotatable shaft oriented transversely to a line of motion of the trigger. The arm is mounted on the shaft and extends transversely thereto. The arm has a free end engageable with the trigger upon rotation of the shaft. 
     As an example, the controller comprises a microprocessor. In an example, the switch comprises a pressure sensitive switch. In a particular example, the switch comprises a momentary switch. In another particular example, the switch comprises a push to close type switch. 
     In an example, the device further comprises a conduit in fluid communication with the pressure sensitive switch. The conduit is for conveying a change in gas pressure to the pressure sensitive switch. 
     In an example, the controller is adapted to transmit a third command to the actuator for moving the body into engagement with the trigger in preparation for pulling the trigger. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a right side view of a firearm having an example device for remotely pulling the trigger according to the invention; 
         FIG. 2  is a left side view of the firearm and device shown in  FIG. 1 ; 
         FIG. 3  is an isometric view of an example actuator used in the device shown in  FIG. 1 ; 
         FIG. 4  shows a shooter using the device shown in  FIG. 1 ; 
         FIGS. 5-7  show steps in the operation of the actuator shown in  FIG. 3 ; and 
         FIG. 8  is a flow chart illustrating an example method of remotely pulling a trigger of a firearm according to the invention. 
     
    
    
     DETAILED DESCRIPTION 
       FIGS. 1 and 2  show a device  10  for pulling a trigger  12  of a firearm  14 , in this example an air rifle. Device  10  comprises an actuator  16 , shown in  FIG. 1  mounted on a trigger guard  18  adjacent to the trigger  12 . In the example embodiment shown the mounting of the actuator is effected using pull ties  20  and a screw clamp  22 .  FIG. 3  shows the actuator  16  in detail, which, in this example comprises a servo motor  24  having a rotatable shaft  26  with its axis of rotation  27  oriented transversely to a line of motion  28  of trigger  12 . A body, in this example comprising an arm  30  is mounted on and extends transversely to the shaft  26 . The arm  30  has a free end  32  which is engageable with the trigger  12  upon rotation of the shaft  26 . 
     Device  10  further comprises a controller  34 , shown in  FIG. 2 . In this example embodiment, the controller  34  is mounted on the fore end of the firearm and comprises a microprocessor, for example a commercially available programmable logic controller such as the Arduino Nano made by Arduino of Ivera, Italy. Controller  34  is electrically powered by an internal battery for example, and is in communication with the actuator  16  (also electrically powered) via an electrically conducting cable  36  over which the controller transmits commands to the actuator  16  which control rotation of shaft  26 . Example commands include, a first command for moving arm  30  into engagement with the trigger  12  for pulling the trigger, a second command for moving the arm out of engagement with the trigger to permit the trigger to reset, as well as a third command to “stage” the arm  30  by moving it into engagement with the trigger  12  so that it is ready to move further into engagement and pull the trigger. These commands are described in detail below. 
     Device  10  also includes a switch  38  in communication with the controller. Switch  38  comprises the user interface to the controller and is adapted to transmit a first signal to the controller for causing the controller to transmit the first command to the actuator, and transmit a second signal to the controller to transmit the second command to the actuator as described below. Although any adaptive switch can be plugged into the controller, this example embodiment uses an integrated pressure sensitive switch  38  which can be opened and closed by a change in gas pressure. A conduit  40  is in fluid communication with the switch  38  and is used to convey a change in gas pressure to the switch. The sensitivity of the switch  38  is such that a user can trip the switch by orally drawing on the conduit to create a drop in pressure or blowing into the conduit to create an increase in pressure on the switch. It is advantageous for the switch to comprise a momentary push to close type switch for reliable transmission of signals to the controller  34 . 
       FIGS. 4-7  and the flow chart of  FIG. 8  illustrate an example method for remotely pulling the trigger  12  of the firearm  14 . As shown in  FIG. 4 , a shooter  42  places the end of conduit  40  in his mouth as one would a drinking straw. (In this example the controller is mounted on the shoulder stock of the firearm.) The shooter then aims the firearm  14  to acquire the target.  FIG. 5  shows the actuator  16 , which is in the “reset” position during target acquisition, with the arm  30  not yet engaged with the trigger  12 . The shooter  42  then transmits a first signal to the controller by changing the pressure within conduit  40 . In this example the shooter blows into the conduit  40 , which closes the pressure sensitive switch  38 , causing the controller  34  to command the servo motor  24  to rotate the shaft  26  into a first position, shown in  FIG. 6 , with the free end  32  of arm  30  engaged with the trigger  12 . Pressure is let off the switch  38 , allowing it to open. Once the shooter  42  has taken final aim he transmits a second signal to the controller  34  by again blowing into the conduit  40  and increasing the gas pressure therewithin to close the switch  38 . In response the controller  34  measures the time period between transmission of the first and second signals. If the measured time period is less than a threshold value, in a practical example, three seconds, then the controller  34  commands the servo motor  24  to further rotate the shaft  26 , which causes the arm  30  to pull the trigger  12  as shown in  FIG. 7 , thereby firing the firearm. The controller then commands the servo motor  24  to rotate the shaft  26  so that arm  30  moves back to the reset position shown in  FIG. 5  to allow trigger  12  to reset. However, if the measured time period is greater than the threshold value the controller  34  commands the servo motor  24  to rotate the shaft  26  so that the arm  30  moves back to the reset position shown in  FIG. 5  without pulling the trigger  12 . 
     Accuracy is improved by first staging the arm  30  into engagement with the trigger  12 , and then, upon a second command, pulling the trigger to fire the firearm. This two-step process allows the shooter to first acquire the target, then position the arm  30  so that it engages the trigger, and then take final steady aim and pull the trigger with an acceptable amount of lag time between when the second command is given and when the trigger is pulled. Pulling the trigger directly from the reset position takes too long, and it is difficult to hold the aim point during this time period. The two-step process also provides greater safety, as the arm  30  only remains in contact with the trigger  12  for a short period of time and returns to the reset position from which the potential for an accidental discharge is mitigated.