Surgical Stapler Motor Velocity Control With Closed-Loop Feedback
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Solution Overview
Problem
Motorized surgical stapling and cutting instruments face challenges in accurately controlling the velocity of cutting members, leading to errors between commanded and actual velocities, which can affect tissue processing during surgical procedures.
Innovation Solution
A method is implemented using a surgical instrument with a displacement member, motor, position sensor, and timer circuit to set a directed velocity, determine actual velocity, calculate errors, and adjust the motor control to maintain precise velocity control through closed-loop feedback, allowing for real-time adjustments based on user input and tissue conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a motorized surgical stapling and cutting instrument is used to control the velocity of a cutting member, then the productivity and surgical efficiency are improved, but velocity controlled system errors occur between commanded and actual velocities
Solution Approach 1:
The patent implements a closed-loop feedback control system that continuously measures the actual velocity of the cutting member using position sensors and timer circuits, compares it to the commanded velocity, and adjusts the motor output to eliminate velocity errors. This feedback mechanism resolves the contradiction by maintaining both high productivity through motorized operation and high reliability through continuous velocity correction.
2Reliability
If a closed loop feedback system is implemented to correct velocity errors, then the velocity control accuracy is improved, but the device complexity increases
Solution Approach 1:
The feedback system uses position sensors already present in the motorized instrument and timer circuits to measure actual velocity, then feeds this information back to the control circuit which adjusts motor velocity. This approach improves velocity control accuracy while minimizing added complexity by utilizing existing instrument components rather than introducing entirely new sensing or actuation systems.
3Adaptability or versatility
If the velocity of the cutting member is adjusted based on tissue conditions, then the adaptability to different tissue thicknesses is improved, but the control system complexity increases
Solution Approach 1:
The system measures actual cutting member velocity and compares it to expected velocity to infer tissue conditions such as tissue thickness. The control circuit then adjusts velocity commands based on this feedback, enabling adaptation to different tissue conditions without requiring complex pre-programmed tissue classification algorithms or additional tissue sensing hardware.
Solution Approach 2:
The control system uses the velocity measurements from the cutting member itself to infer tissue conditions and adjust subsequent velocity commands. This self-service approach allows the system to adapt to tissue conditions using data already generated during normal operation, rather than requiring separate tissue characterization systems.
Data Source
AI summary
A method of operating a surgical instrument is disclosed comprising driving a displacement driver a first distance with a motor, measuring a time period required to drive the displacement driver the first distance, presenting an indicia on a display indicative of a velocity mode for the displacement driver, receiving a user input corresponding to the velocity mode, and setting a velocity of the motor based on the user input.