A surgical instrument assembly configured to be attached to and detached from a surgical robot is disclosed. The surgical instrument assembly comprises a drive system actuatable in a first direction and a second direction which is opposite the first direction, wherein the drive system is configured to perform an instrument function, a shaft, and an end effector. The surgical instrument assembly further comprises a drive system bailout comprising position indication means for indicating the position of the drive system and an actuation member configured to actuate the drive system in the first direction and the second direction, wherein the direction in which the drive system bailout is operated is based on the position of the drive system indicated by the position indication means.