Surgical Stapler Motor Velocity Feedback Using Time-Over-Distance
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Solution Overview
Problem
Motorized surgical stapling and cutting instruments face challenges in accurately controlling the velocity of cutting members and articulation of end effectors to adapt to varying tissue conditions, leading to inconsistent performance and potential tissue damage.
Innovation Solution
A surgical instrument equipped with a displacement member, motor, position sensor, and timer circuit that measures elapsed time over predefined zones to adjust the command velocity, enabling closed-loop feedback control and adaptive velocity adjustment based on tissue conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If open loop control is used for motor velocity, then device complexity is reduced, but velocity precision and tissue condition adaptability deteriorate
Solution Approach 1:
The patent implements closed-loop feedback control by measuring the actual velocity of the cutting member using position sensors and timers, comparing it to the commanded velocity, and adjusting motor control signals to eliminate velocity errors. This feedback mechanism enables precise velocity control that adapts to varying tissue conditions during stapling and cutting operations.
2Ease of operation
If constant velocity is maintained, then operation simplicity is improved, but tissue condition adaptability and safety deteriorate
Solution Approach 1:
The patent implements dynamic velocity control where the commanded velocity is adjusted in real-time based on measured tissue conditions. The system transitions from static constant velocity to dynamic adaptive velocity, allowing the cutting member speed to vary according to tissue thickness and density, thereby improving safety and effectiveness while maintaining automated operation.
3Productivity
If high velocity is used for cutting, then productivity is improved, but force on cutting member and tissue damage increase
Solution Approach 1:
The patent dynamically changes the velocity parameter of the cutting member based on real-time feedback from position measurements. By adjusting velocity according to actual tissue conditions encountered during the firing stroke, the system optimizes cutting efficiency while preventing excessive forces that could cause tissue damage or instrument malfunction.
Data Source
AI summary
A motorized surgical instrument is disclosed. The surgical instrument includes a displacement member, a motor coupled to the displacement member, a control circuit coupled to the motor, a position sensor coupled to the control circuit, and a timer circuit coupled to the control circuit. The control circuit is configured to receive, from the position sensor, a position of the displacement member in a current zone defined by a set displacement interval, measure time at a set position of the displacement interval, wherein the measured time is defined as the time taken by the displacement member to traverse the displacement interval, and set a command velocity of the displacement member for a subsequent zone based on the measured time in the current predefined zone.