Surgical instrument having controllable articulation velocity

1 . A surgical instrument comprising:

an articulation driver configured to drive an end effector that is articulatable between a first position and a second position, the articulation driver configured to drive the end effector from the first position to the second position;

a shaft assembly coupled to the end effector, wherein an end effector axis of the end effector is coaxially aligned or parallel with a shaft axis of the shaft assembly when the end effector is in the first position, and wherein the end effector axis intersects the shaft axis at a predetermined angle when the end effector is in the second position;

a motor coupled to the articulation driver, the motor configured to drive the articulation driver;

a sensor configured to detect a position of the articulation driver and provide a signal indicative of the position of the articulation driver during an articulation actuation motion; and

a control circuit coupled to the motor and the sensor, the control circuit configured to:

determine a position of the articulation driver via the signal provided by the sensor;

determine an articulation angle of the end effector according to the signal indicative of the position of the articulation driver, wherein the articulation angle is an angle defined by the end effector axis and the shaft axis;

provide a drive signal to the motor during the articulation actuation motion to automatically drive the motor at a velocity corresponding to the determined articulation angle of the end effector to articulate the end effector at an articulation velocity corresponding to the determined articulation angle of the end effector; and

automatically adjust the drive signal to adjust the articulation velocity of the end effector according to the articulation angle of the end effector.

2 . The surgical instrument of claim 1 , wherein the drive signal causes the motor to drive the end effector at a fixed articulation velocity when the determined articulation angle of the end effector is within a designated zone between the first position and the second position.

3 . The surgical instrument of claim 2 , wherein the designated zone corresponds to a threshold distance from a position between the first position and the second position.

4 . The surgical instrument of claim 1 , wherein the drive signal varies according to the position of the end effector and the drive signal causes the motor to drive the end effector at a variable articulation velocity according to the determined articulation angle of the end effector.

5 . The surgical instrument of claim 1 , wherein the drive signal has a variable duty cycle that varies according to the determined articulation angle of the end effector.

6 . The surgical instrument of claim 1 , wherein the end effector is further articulatable between the first position and a third position, wherein the articulation driver is configured to drive the end effector from the second position to the third position, and

wherein the second position is a first end of an articulation range of the end effector and the third position is a second end of the articulation range of the end effector.

7 . A surgical instrument, comprising:

a shaft;

an articulation joint; and

an end effector attached to said shaft by way of said articulation joint, wherein said end effector is configured to be articulated between a plurality of angular positions, wherein said plurality of angular positions comprises an articulated position and a straight position, wherein an end effector axis of the end effector is coaxially aligned or parallel with a longitudinal axis of the shaft when the end effector is in the straight position, and wherein the end effector axis intersects the longitudinal axis of the shaft when the end effector is in the articulated position;

an articulation driver extending through said shaft to said articulation joint, wherein said articulation driver is actuatable to articulate said end effector between said articulated position and said straight position;

a motor coupled to the articulation driver;

a sensor configured to detect a position of the articulation driver and configured to provide a signal indicative of the position of the articulation driver during an articulation actuation motion; and

a control circuit coupled to the motor and the sensor, wherein the control circuit is configured to:

receive the signal provided by the sensor;

determine the position of the articulation driver based on the received signal;

determine an articulation angle of the end effector based on the determined position of the articulation driver, wherein the articulation angle is an angle defined by the end effector axis and the longitudinal axis of the shaft;

provide a drive signal to the motor to articulate the end effector at an articulation velocity corresponding to the determined articulation angle of the end effector to adjust the articulation actuation motion of the end effector; and

automatically adjust the drive signal to adjust the articulation velocity of the end effector according to the articulation angle of the end effector.

8 . The surgical instrument of claim 7 , wherein the drive signal causes the motor to articulate the end effector about said articulation joint at a fixed articulation velocity when the determined articulation angle of the end effector is within a designated zone between the articulated position and the straight position.

9 . A surgical instrument, comprising:

a shaft;

an articulation joint; and

an end effector attached to said shaft by way of said articulation joint, wherein said end effector is configured to be articulated relative to said shaft between a plurality of angular positions, wherein said plurality of angular positions comprises an articulated position and a non-articulated position, wherein an end effector axis of the end effector is coaxially aligned or parallel with a longitudinal axis of the shaft when the end effector is in the non-articulated position, and wherein the end effector axis intersects the longitudinal axis of the shaft when the end effector is in the articulated position;

an articulation drive member actuatable to articulate said end effector between said plurality of angular positions;

a motor coupled to the articulation drive member;

a sensor configured to detect a linear position of the articulation drive member and configured to provide a signal indicative of the linear position of the articulation drive member during an articulation actuation motion; and

a control circuit coupled to the motor and the sensor, wherein the control circuit is configured to:

receive the signal provided by the sensor;

determine the linear position of the articulation drive member based on the received signal;

determine an articulation angle of the end effector based on the determined linear position of the articulation drive member, wherein the articulation angle is an angle defined by the end effector axis and the longitudinal axis of the shaft;

provide a drive signal to the motor to actuate the articulation drive member at a velocity corresponding to the determined articulation angle of the end effector to automatically adjust the articulation actuation motion of the end effector; and

automatically adjust the drive signal to adjust an articulation velocity of the end effector according to the articulation angle of the end effector.

10 . The surgical instrument of claim 9 , wherein the drive signal causes the motor to articulate the end effector about said articulation joint at a fixed articulation velocity when the determined articulation angle of the end effector is within a designated zone between the articulated position and the straight position.