Robotic surgical assemblies

An instrument drive unit, comprising:

• a hub;
• a motor pack coupled to the hub and configured to rotate relative to the hub about a longitudinal axis defined by the motor pack;
• and
• at least one annular member rotatably supported on the hub and in operative association with the motor pack, wherein the motor pack is configured rotate relative to the at least one annular member from a first position to a second position upon which rotation of the motor pack drives a rotation of the at least one annular member relative to the hub.

An instrument drive unit for use with a robotic arm, the instrument drive unit comprising:

• an outer shell configured to be coupled to a robotic arm;
• a drive motor selectively moveable in an orbit within the outer shell around a central axis;
• an interface coupled to the outer shell and configured to be selectively couplable to a surgical instrument;
• at least one annular member rotatably supported by the outer shell and in operative association with the drive motor;
• wherein as the drive motor is rotated in the orbit the drive motor rotates the at least one annular member from a first position to a second position relative to the outer shell;
• and
• a drive motor output coupled to the drive motor and configured to be coupled to an input of a surgical instrument when the interface is coupled to an interface of the surgical instrument.

An instrument drive unit for use with a robotic arm, the instrument drive unit comprising:

• an outer shell configured to be selectively coupled to a robotic arm;
• a hub non-rotatably received within the outer shell and having an axially extending surface feature;
• a motor pack including a proximal end rotatably coupled to the hub, and a surface feature extending axially therefrom;
• a first annular member defining a first annular channel having the surface feature of the hub received therein, the first annular member having a stop formed in the first annular channel thereof;
• and
• a second annular member associated with the first annular member and defining a second annular channel, the second annular member having a stop formed in the second annular channel thereof, wherein upon the motor pack achieving a threshold amount of rotation relative to the hub, the surface feature of the motor pack abuts the stop of the second annular channel of the second annular member to rotate the second annular member relative to the hub, and wherein upon the first annular member achieving a threshold amount of rotation relative to the hub, the stop of the first annular channel of the first annular member abuts the surface feature of the hub stopping further rotation of the motor pack.