A flexible robotic endoscopy slave system includes an endoscope body and a flexible elongate shaft extending therefrom into which at least one tendon driven robotic endoscopic instrument is insertable; a docking station with which the endoscope body is releasably dockable; and a translation mechanism for selectively longitudinally displacing the endoscopic instrument(s) within the flexible elongate shaft when the endoscope body is docked. The translation mechanism can carry and selectively displace actuators that drive each robotic endoscopic instrument by way of tendons. At least one degree of freedom (DOF) of robotic instrument motion is controlled by a pair of actuators and a corresponding pair of tendons. Actuation engagement structures releasably couple the actuators to an adapter structure for driving each endoscopic instrument. Tendon pretensioning can occur automatically under programmable control. A roll joint without tendon crimping structures can be employed in a robotic endoscopic instrument for reducing tendon wear and roll joint spatial volume.