Torque optimization for surgical instruments

Abstract

A control system having speed management control. The control system can be in signal communication with a battery, and the battery can be coupled to a motor. The speed management control can include a pulse width modulation circuit, which can control the duration of pulses supplied from the battery to the motor. The motor can include a primary set of coils and a secondary set of coils. The control system can direct surplus current to the secondary set of coils to maximize the torque generated by the motor.

What is claimed is: 
     
         1 . A surgical stapler, comprising:
 an end effector comprising a plurality of deployable staples and a firing element;   a motor configured to drive said firing element, wherein said motor comprises a primary set of coils and a secondary set of coils; and   a control system in signal communication with said motor, wherein said control system comprises:
 a battery; 
 a pulse width modulation circuit configured to control the duration of current pulses supplied from said battery to said motor; and 
 a switch configured to switch the electric motor between a plurality of operating states, wherein the plurality of operating states comprises:
 a first operating state in which the primary set of coils are configured to drive said firing element; and 
 a second operating state in which said primary set of coils and said secondary set of coils are configured to drive said firing element. 
 
   
     
     
         2 . The surgical stapler of  claim 1 , wherein the battery supplies current pulses to said primary set of coils at a voltage that corresponds to the maximum torque of said primary set of coils during the first operating state. 
     
     
         3 . The surgical stapler of  claim 2 , wherein a surplus current is supplied to said secondary set of coils during the second operating state. 
     
     
         4 . The surgical stapler of  claim 3 , wherein said control system maximizes the surplus current supplied to said secondary set of coils during the second operating state based on the volt-ampere limit of said battery. 
     
     
         5 . The surgical instrument of  claim 1 , wherein said motor generates a first amount of torque during the first operating state, wherein said motor generates a second amount of torque during the second operating state, and wherein the second amount of torque is greater than the first amount of torque. 
     
     
         6 . The surgical stapler of  claim 5 , wherein said motor drives said firing element in a first direction during the first operating state, wherein said motor drives said firing element in a second direction during the second operating state, and wherein the second direction is opposite to the first direction. 
     
     
         7 . The surgical stapler of  claim 6 , wherein the first direction comprises a distally advancing direction, and wherein the second direction comprises a proximally retracting direction. 
     
     
         8 . The surgical stapler of  claim 1 , wherein said motor comprises a stepper motor. 
     
     
         9 . A surgical stapler, comprising:
 an end effector comprising a plurality of deployable staples and a firing element;   a control system, comprising:
 a battery; and 
 a pulse width modulation circuit configured to control the duration of current pulses supplied from said battery; and 
   a motor in signal communication with said control system and configured to drive said firing element, wherein said motor comprises:
 a primary set of coils configured to generate a first amount of torque, wherein the first amount of torque drives said firing element in a first direction; and 
 a secondary set of coils configured to generate a second amount of torque, wherein the first amount of torque and the second amount of torque drive said firing element in a second direction. 
   
     
     
         10 . The surgical stapler of  claim 9 , wherein said battery is configured to supply current pulses to said primary set of coils at a voltage that corresponds to the maximum torque of said primary set of coils. 
     
     
         11 . The surgical stapler of  claim 10 , wherein said battery operably supplies a surplus current to said secondary set of coils. 
     
     
         12 . The surgical stapler of  claim 9 , wherein said control system maximizes the torque generated by said primary set of coils and the secondary set of coils when driving said firing element in the second direction. 
     
     
         13 . The surgical stapler of  claim 9 , wherein the second direction is opposite to the first direction. 
     
     
         14 . The surgical stapler of  claim 5 , wherein the second direction comprises a proximal direction. 
     
     
         15 . The surgical stapler of  claim 1 , wherein said motor comprises a stepper motor. 
     
     
         16 . A surgical stapler, comprising:
 an end effector comprising a plurality of deployable staples and a firing element;   a motor configured to drive said firing element, wherein said motor comprises a primary set of coils; and   a control system in signal communication with said motor, wherein said control system comprises:
 a battery; and 
 a pulse width modulation circuit configured to control the duration of current pulses supplied from said battery to said primary set of coils. 
   
     
     
         17 . The surgical stapler of  claim 16 , wherein said motor further comprises a secondary set of coils, and wherein said control system comprises a switch configured to operably supply current from said battery to said secondary set of coils. 
     
     
         18 . The surgical stapler of  claim 17 , wherein said battery supplies current to said primary set of coils during a first operating state, and wherein said battery supplies current to said primary set of coils and said secondary set of coils during a second operating state. 
     
     
         19 . The surgical stapler of  claim 18 , wherein said motor drives said firing element distally during the first operating state, and wherein said motor drives said firing element proximally during the second operating state. 
     
     
         20 . The surgical stapler of  claim 16 , wherein said control system optimizes the torque generated by said motor. 
     
     
         21 . The surgical stapler of  claim 16 , wherein said motor comprises a stepper motor.