Force transmission systems using planetary gear assembly, and related devices and methods

An instrument comprising:

• a shaft;
• an articulable component coupled to the shaft and configured to articulate relative to the shaft;
• a force transmission system coupled to the shaft and comprising:
• a ring gear,
• a first planet gear meshed with the ring gear,
• a second planet gear meshed with the ring gear,
• a first lead screw comprising left-hand screw threading in threaded engagement with the first planet gear, and
• a second lead screw comprising right-hand screw threading in threaded engagement with the second planet gear;
• a first actuation member extending through the shaft and operably coupled to the articulable component and the first lead screw;
• and
• a second actuation member extending through the shaft and operably coupled to the articulable component and the second lead screw.

A method of tensioning first and second actuation members coupled to an articulable structure of a medical instrument, the method comprising:

• applying a first tensile force to a first actuation member coupled to a first lead screw by driving the first lead screw;
• applying a second tensile force to a second actuation member coupled to a second lead screw by driving the second lead screw;
• maintaining the first tensile force in the first actuation member by coupling the first lead screw with a first planet gear and meshing the first planet gear to a ring gear;
• and
• maintaining the second tensile force in the second actuation member by engaging the second lead screw with a second planet gear and meshing the second planet gear to the ring gear.