Surgical robotic system and method for detection and prediction of cable breakage

A surgical robotic system comprising:

• an instrument drive unit including a plurality of motors including a first pair motors and a second pair of motors, wherein each motor of the plurality of motors includes a torque sensor for measuring motor torque and a position sensor for measuring angular position;
• an instrument coupled to the instrument drive unit, the instrument including:
• an end effector having a first jaw and a second jaw each movable between an open position and a closed position;
• a first pair of cables each of which is actuated by one motor of the first pair motors to move the first jaw and the second jaw toward the closed position, wherein one of the first pair of cables is coupled to the first jaw and another of the first pair of cables is coupled to the second jaw;
• and
• a second pair of cables each of which is actuated by one motor of the second pair motors to move the first jaw and the second jaw toward the open position, wherein one of the second pair of cables is coupled to the first jaw and another of the second pair of cables is coupled to the second jaw;
• and
• a controller:
• calculating an angle between the first jaw and the second jaw based on the angular position of at least one motor of the plurality of motors;
• calculating a combined torque of the first pair of motors;
• determining whether at least one cable of the second pair of cables is broken based on the angle between the first jaw and the second jaw and the combined torque;
• and
• outputting an alert based on the determination that at least one cable of the second pair of cables is broken.

A method for controlling a surgical robotic instrument, the method comprising:

• moving apart a first jaw and a second jaw, wherein the first jaw is coupled to a first low-side cable actuatable by a first low-side motor and a second jaw is coupled to a second low-side cable actuatable by a second low-side motor;
• approximating the first jaw and the second jaw, wherein the first jaw is coupled to a first high-side cable actuatable by a first high-side motor and the second jaw is coupled to a second high-side cable actuatable by a second high-side motor;
• measuring torque of each of the first and second high-side motors and first and second low-side motors;
• measuring an angular position of each of the first and second high-side motors and first and second low-side motors;
• calculating, at a controller, an angle between the first jaw and the second jaw based on the angular position of at least one of the first high-side motor, the second high-side motor, the first low-side motor, or the second low-side motor;
• calculating, at the controller, a combined torque of the first high-side motor and the second high-side motor;
• determining, at the controller, whether at least one of the first low-side cable or the second low-side cable is broken based on the angle between the first jaw and the second jaw and the combined torque;
• and
• outputting an alert based on the determination at least one of the first low-side cable or the second low-side cable is broken.