An apparatus (100) for operating in tissue, the apparatus (100) comprising: (a) an end effector (150), where the final effector (150) comprises an ultrasonic blade (160) and an operable clamp arm (152) for pivoting in relation to the ultrasonic blade (160)； (b) a bar assembly (110), where the end effector (150) is disposed at a distal end of the bar assembly (110), where the bar assembly (110) defines a longitudinal axis, where the bar assembly (110) includes an articulation section (130) operable to deflect the end effector (150) away from the longitudinal axis； and (c) an interface assembly (200), where the interface assembly (200) is configured to drive the final effector (150), where the interface assembly (200) comprises: (i) a base (202), where the base (202) is configured to engage a spring (72) of a robotic control system (10), and (ii) a plurality of drive bars (224, 244, 264) oriented perpendicular to the longitudinal axis, where a first drive bar (264) of the plurality of drive bars is rotatable to pivot the clamp arm (152) towards the ultrasonic blade (160)； wherein the bar assembly (110) further comprises a transfer member (174, 176) coupled between the first drive bar (264) and the clamp arm (152)； characterized in that the interface assembly (200) further comprises: (iii) an eccentric cam (266) secured to the first drive bar (264), and (iv) a shelf (270) coupled to the transfer member (174, 176), where the eccentric cam (266) is operable to propel the shelf (270) proximally in response to the rotation of the first drive bar (264) to thus pivot the arm of the clamp (152) towards the ultrasonic blade (160).Un aparato (100) para operar en tejido, comprendiendo el aparato (100): (a) un efector final (150), donde el efector final (150) comprende una cuchilla ultrasónica (160) y un brazo de abrazadera (152) operable para pivotar en relación con la cuchilla ultrasónica (160)； (b) un montaje de barra (110), donde el efector final (150) está dispuesto en un ex
