Systems and subsystems for rolling a surgical instrument including articulation cables

A surgical instrument comprising:

• a shaft assembly comprising:
• a rotatable outer shaft configured to rotate about a roll axis;
• and
• a maypole tube housed within the outer shaft;
• a firing rod that extends within the maypole tube and is configured to move a knife in an end effector;
• and
• one or more articulation cables, each articulation cable being configured (i) to be manipulable to cause rotation of the end effector about at least one of a pitch axis and a yaw axis and (ii) to wrap around the maypole tube when the rotatable outer shaft rotates about the roll axis.

A control device for adjusting a length of a cable of a surgical instrument, the surgical instrument comprising the cable and a shaft, the cable comprising (i) a section with an initial length defined between a rotatable point of the cable that is rotatable with the shaft relative to a rotationally restrained proximal point of the cable and (ii) an initial tension at a zero degree roll angle, the control device being configured to:

• receive a non-zero degree roll angle of the rotatable point of the cable that is rotated with the shaft relative to the rotationally restrained proximal point of the cable;
• determine a change in length of the section of the cable, relative to the initial length, that maintains the cable at the initial tension;
• calculate a cable compensation length by multiplying the determined change in length of the section of the cable by a factor;
• and
• deliver a signal to change the length of the section of the cable based on the calculated cable compensation length.

A surgical system comprising:

• a surgical instrument comprising:
• a housing;
• a shaft assembly extending from the housing and comprising:
• an outer shaft configured to rotate about a roll axis;
• and
• a maypole tube housed within the outer shaft;
• and
• a cable comprising a rotationally restrained point proximal the housing and a rotatable point that is rotatable with the outer shaft, the cable comprising, at a zero-degree roll angle, a length defined between the rotationally restrained point and the rotatable point;
• and
• a control device for adjusting the length of the cable, the control device being configured to:
• receive a non-zero degree roll angle of rotatable point of the cable relative to the rotationally restrained proximal point of the cable;
• determine a change in length of the cable, relative to the length of the cable at the zero-degree roll angle, that maintains the cable at a same tension as the tension in the cable when the cable is at the zero-degree roll angle;
• calculate a cable compensation length by multiplying the determined change in length of the cable by a factor;
• and
• deliver a signal to change the length of the cable based on the calculated cable compensation length.