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EP-4372758-B1 - CLOSED LOOP FEEDBACK CONTROL OF MOTOR VELOCITY OF A SURGICAL STAPLING AND CUTTING INSTRUMENT BASED ON MAGNITUDE OF VELOCITY ERROR MEASUREMENTS

EP4372758B1EP 4372758 B1EP4372758 B1EP 4372758B1EP-4372758-B1

Inventors

  • PARFETT, RAYMOND E.
  • ADAMS, SHANE R.
  • SHELTON, IV, FREDERICK E.
  • HARRIS, JASON L.

Dates

Publication Date
20260506
Application Date
20171221

Claims (7)

  1. A surgical instrument (2500), comprising: a displacement member configured to translate within the surgical instrument; a motor (2504) coupled to the displacement member to translate the displacement member; a control circuit (2510) coupled to the motor; a position sensor (2534) coupled to the control circuit, the position sensor configured to measure the position of the displacement member; and a timer circuit (2531) coupled to the control circuit, the timer circuit configured to measure elapsed time; wherein the control circuit is configured to: set a directed velocity of the displacement member; determine a position of the displacement member; determine an actual velocity of the displacement member; compare the directed velocity of the displacement member to the actual velocity of the displacement member; determine an error between the directed velocity of the displacement member and the actual velocity of the displacement member; and adjust the directed velocity of the displacement member at a rate of change based on the error.
  2. The surgical instrument of claim 1, wherein the control circuit is configured to compare the error to multiple error thresholds.
  3. The surgical instrument of claim 2, wherein the control circuit is configured to adjust the directed velocity of the displacement member at multiple rates of change based on the error.
  4. The surgical instrument of claim 2 or claim 3, wherein the control circuit is configured to: compare the error to a first error threshold; and maintain the directed velocity when the error is within the first error threshold.
  5. The surgical instrument of claim 4, wherein the control circuit is configured to: compare the error to a second error threshold; adjust the directed velocity at a first rate of change when the error exceeds the first error threshold and is within the second error threshold.
  6. The surgical instrument of claim 5, wherein the control circuit is configured to: adjust the directed velocity at a second rate of change when the error exceeds both the first error threshold and the second error threshold.
  7. The surgical instrument of any one of claims 1 to 6, wherein the error is based on at least one of a short term error (S), cumulative error (C), rate of change error (R), and number of overshoots error (N).

Description

TECHNICAL FIELD The present disclosure relates to surgical instruments and, in various circumstances, to surgical stapling and cutting instruments and staple cartridges therefor that are designed to staple and cut tissue. BACKGROUND EP3231371A1 (prior art in the meaning of Article 54(3) EPC) relates to systems and methods for operating a surgical instrument comprising a firing member translatable proximally and distally along a longitudinal axis between a stroke begin position to a stroke end position distal of the stroke begin position; a knife coupled to the firing member; and a motor coupled to the firing member to translate the firing member between the stroke begin position and the stroke end position. A control circuit may receive a firing signal and begin a firing member stroke by providing an initial motor setting to the motor. The control circuit may maintain the initial motor setting for an open-loop portion of the firing member stroke. The control circuit may receive firing member motion data describing a motion of the firing member during the open-loop portion of the firing member stroke and may select a firing control program based at least in part on the motion of the firing member during the open-loop portion of the firing member stroke. EP2777539A2 relates to drive system lockout arrangements for modular surgical instruments. EP1040790A2 relates to a method is provided for removing at least one tissue sample from a surgical patient using a biopsy instrument. The method for using the biopsy instrument comprises the steps of engaging tissue in the port; translating the cutter at a first, predetermined translational speed from a first position to a second position proximal to the port; measuring the translational speed of the cutter; translating the cutter at a second, predetermined translational speed from the second position to a third position proximal to the port; translating the cutter at a third, predetermined translational speed from the third position to a fourth position distal to the port; rotating the cutter at a predetermined rotation speed; measuring the rotational speed of the cutter; and modifying the translational speed of the cutter when the rotational speed of the cutter varies from the predetermined rotational speed by more than a first, predetermined differential rotational speed. EP2923661A2 relates to a surgical system comprising a sensor system. In a motorized surgical stapling and cutting instrument it may be useful to control the velocity of a cutting member or to control the articulation velocity of an end effector. Velocity of a displacement member may be determined by measuring elapsed time at predetermined position intervals of the displacement member or measuring the position of the displacement member at predetermined time intervals. The control may be open loop or closed loop. Such measurements may be useful to evaluate tissue conditions such as tissue thickness and adjust the velocity of the cutting member during a firing stroke to account for the tissue conditions. Tissue thickness may be determined by comparing expected velocity of the cutting member to the actual velocity of the cutting member. In some situations, it may be useful to articulate the end effector at a constant articulation velocity. In other situations, it may be useful to drive the end effector at a different articulation velocity than a default articulation velocity at one or more regions within a sweep range of the end effector. During use of a motorized surgical stapling and cutting instrument it is possible that a velocity controlled system error may occur between the command velocity and the actual measured velocity of the cutting member or firing member. Therefore, it may be desirable to provide a closed loop feedback system that adjusts the velocity of the cutting member or firing member based on the magnitude of one or more error terms determined based on the difference between an actual speed and a command speed over a specified increment of time/distance. SUMMARY The invention is defined in the appended claims. In one aspect, the present disclosure provides a surgical instrument. The surgical instrument comprises a displacement member configured to translate within the surgical instrument; a motor coupled to the displacement member to translate the displacement member; a control circuit coupled to the motor; a position sensor coupled to the control circuit, the position sensor configured to measure the position of the displacement member; a timer circuit coupled to the control circuit, the timer circuit configured to measure elapsed time; wherein the control circuit is configured to: set a directed velocity of the displacement member; determine a position of the displacement member; determine an actual velocity of the displacement member; compare the directed velocity of the displacement member to the actual velocity of the displacement member; determine an error between the directed