A robotic surgical assembly comprising: a robotic arm (2, 3) having a mount; an instrument drive unit mounted on the mount of the robotic arm (2,3), the instrument drive unit including: a plurality of actuators (314a-f); a plurality of linkage members, each linkage member having opposing first and second portions (352a, 352b), the first portion operatively coupled to respective one of the plurality of actuators (314a-f) such that actuation of the respective one of the plurality of actuators (314a-f) moves the first portion in a first direction and the second portion in a second direction opposite of the first direction; and a plurality of drive members, each one of the plurality of drive members operatively coupled to the second portion of respective one of the plurality of linkage members; and a surgical instrument detachably coupled to the instrument drive unit, the surgical instrument including: a plurality of driven members (262a-d), each of the plurality of driven members (262a-d) operatively associated with respective one of the plurality of drive members of the instrument drive unit; and an end effector operatively coupled with the plurality of driven members (262a-d), wherein translation of at least one of the plurality of driven members ( 2 6 2 a - d) effects a first function of the end effector. a robotic arm (2, 3) having a mount; an instrument drive unit mounted on the mount of the robotic arm (2,3), the instrument drive unit including: a plurality of actuators (314a-f); a plurality of linkage members, each linkage member having opposing first and second portions (352a, 352b), the first portion operatively coupled to respective one of the plurality of actuators (314a-f) such that actuation of the respective one of the plurality of actuators (314a-f) moves the first portion in a first direction and the second portion in a second direction opposite of the first direction; and a plurality of drive members, each one of the plurality of drive members operatively coupled to the second portion of respective one of the plurality of linkage members; and a surgical instrument detachably coupled to the instrument drive unit, the surgical instrument including: a plurality of driven members (262a-d), each of the plurality of driven members (262a-d) operatively associated with respective one of the plurality of drive members of the instrument drive unit; and an end effector operatively coupled with the plurality of driven members (262a-d), wherein translation of at least one of the plurality of driven members ( 2 6 2 a - d) effects a first function of the end effector. a plurality of actuators (314a-f); a plurality of linkage members, each linkage member having opposing first and second portions (352a, 352b), the first portion operatively coupled to respective one of the plurality of actuators (314a-f) such that actuation of the respective one of the plurality of actuators (314a-f) moves the first portion in a first direction and the second portion in a second direction opposite of the first direction; and a plurality of drive members, each one of the plurality of drive members operatively coupled to the second portion of respective one of the plurality of linkage members; and a surgical instrument detachably coupled to the instrument drive unit, the surgical instrument including: a plurality of driven members (262a-d), each of the plurality of driven members (262a-d) operatively associated with respective one of the plurality of drive members of the instrument drive unit; and an end effector operatively coupled with the plurality of driven members (262a-d), wherein translation of at least one of the plurality of driven members ( 2 6 2 a - d) effects a first function of the end effector. a plurality of driven members (262a-d), each of the plurality of driven members (262a-d) operatively associated with respective one of the plurality of drive members of the instrument drive unit; and an end effector operatively coupled with the plurality of driven members (262a-d), wherein translation of at least one of the plurality of driven members ( 2 6 2 a - d) effects a first function of the end effector.