Surgical Instrument Jaw Control via Shaft Rotation Feedback
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Solution Overview
Problem
Existing robotic surgical systems face challenges in maintaining consistent force between jaw members due to changes in path lengths of elongate elements caused by shaft rotation, especially when using speed reducers with higher reduction ratios.
Innovation Solution
A surgical system and method that control the rotation amounts of drive parts to maintain a desired opening angle between jaw members, correcting for shaft rotation angles to adjust the path lengths of elongate elements and minimize force changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a speed reducer with a higher reduction ratio is used to downsize the motor, then the motor size is reduced, but the torque change is less likely to be reflected to the distal end members
Solution Approach 1:
The system uses feedback from torque sensors to detect the actual torque applied to the motor. The control unit receives this torque information and uses it to calculate corrected rotation amounts, ensuring that the distal end members respond accurately to the surgeon's operational input despite the higher reduction ratio.
Solution Approach 2:
The control unit dynamically changes the rotation amount parameter based on the detected torque. By adjusting the rotation amount in response to torque feedback, the system compensates for the reduced torque transmission efficiency caused by the higher reduction ratio, maintaining reliable control of the distal end members.
2Ease of operation
If the path lengths of elongate elements change due to shaft rotation, then the opening angle control becomes inaccurate, but the system continues to operate
Solution Approach 1:
The system uses feedback from the relationship between rotational amount and opening angle to detect deviations caused by path length changes. The control unit receives this feedback and calculates corrected rotation amounts to compensate for the inaccuracies, maintaining precise opening angle control despite shaft rotation.
Solution Approach 2:
The control unit pre-calculates correction values based on the detected rotational amount and opening angle relationship. By applying these corrections in advance to the rotation commands, the system prevents opening angle inaccuracies before they affect surgical operation precision.
3Volume of moving object
If torque control is used with a higher reduction ratio speed reducer, then motor size is reduced, but it becomes difficult to detect the behavior of distal end members
Solution Approach 1:
The system implements feedback by detecting the torque applied to the motor and using this information to infer the behavior of distal end members. The control unit processes the torque feedback to determine the state and movement of the surgical instrument's working members, enabling detection despite the higher reduction ratio.
Solution Approach 2:
The torque sensor acts as an intermediary between the motor and the distal end members. It provides indirect measurement of distal end member behavior through torque detection, allowing the control unit to monitor surgical instrument operation without direct sensing at the distal end.
Data Source
AI summary
A surgical system according to an embodiment may include a patient-side apparatus, an operator-side apparatus including an operation part to receive an operation for operating a surgical instrument attached to an arm of the patient-side apparatus, and a controller configured to control an operation of the surgical instrument based on the operation received by the operation part. The controller is configured to: control rotation amounts of first and second drive parts to drive first and second elongate elements for opening and closing first and second jaw members of the surgical instrument such that an opening angle between the first and second jaw members correspond to an operating angle received by the operation part; and correct, according to a rotation angle of a shaft of the surgical instrument about a rotation axis of the shaft, the rotation amounts of the first and second drive parts that correspond to the operating angle.