Tension control in actuation of multi-joint medical instruments

An instrument system including:

• an instrument comprising one or more joints;
• a plurality of actuators;
• a plurality of transmission systems having:
• first ends connected to the plurality of actuators, and
• second ends connected to the one or more joints;
• one or more sensors to measure a current configuration of the instrument;
• and
• a control system configured to execute instructions to perform operations comprising:
• determining a first difference between the measured current configuration of the instrument and a desired configuration of the instrument,
• determining, based on the first difference, one or more desired torques to be applied to the one or more joints,
• determining, based on the one or more desired torques to be applied to the one or more joints, a set of tensions to apply to the plurality of transmission systems, and
• generating control signals that cause the plurality of actuators to apply the set of tensions to the plurality of transmission systems to move the instrument toward the desired configuration

An instrument system including:

• a plurality of actuators;
• an instrument comprising
• an end effector, and
• a plurality of transmission systems, each transmission system coupling the end effector to a respective actuator of the plurality of actuators such that the plurality of actuators is operable to drive the plurality of transmission systems and move the end effector in multiple degrees of freedom of motion;
• and
• a control system operably connected to the plurality of actuators, the control system configured to execute operations including:
• operating the plurality of actuators to apply tensions to the plurality of transmission systems based on positions of the plurality of actuators and a desired configuration of the end effector, and to inhibit slack in the plurality of transmission systems while the tensions are applied.

A method of controlling an instrument system, the instrument system comprising:

• an instrument comprising one or more joints, a plurality of actuators, and a plurality of transmission systems coupled to the one or more joints and the plurality of actuators, the method comprising:
• determining a first difference between a measured current configuration of the instrument and a desired configuration of the instrument,
• determining, based on the first difference, one or more desired torques to be applied to the one or more joints,
• determining, based on the one or more desired torques to be applied to the one or more joints, a set of tensions to apply to the plurality of transmission systems, and
• generating control signals that cause the plurality of actuators to apply the set of tensions to the plurality of transmission systems to move the instrument toward the desired configuration.