Surgical apparatus

A surgical instrument, comprising:

• a carriage mounted on a base, the carriage moveable linearly on the base;
• at least one support extending from, and supported by, the carriage;
• at least one frame supported on the carriage, the frame moveable linearly by linear movement of the carriage, and also moveable rotationally about an axis extending from the support;
• at least one robotic controller supported by the at least one frame, wherein the at least one robotic controller is linearly moveable inwardly and outwardly of the at least one frame;
• a coupling configured to connect to a steerable member, the end of which is configured with an end effector actuable by operation of the at least one robotic controller;
• and
• a flexible sheath coupling configured to connect to a flexible sheath.