Surgical Stapler Motor Velocity Control With Stall Feedback
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Solution Overview
Problem
Existing motorized surgical stapling and cutting instruments face challenges in accurately controlling the velocity of the cutting member, leading to potential system errors between the commanded and actual velocities.
Innovation Solution
A method is provided for adjusting the velocity of a motorized surgical instrument by setting a directed velocity, determining the actual velocity, calculating the error between the two, and using a control circuit to adjust the actual velocity based on the error magnitude.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If open loop control is used to control motor velocity, then device complexity is reduced, but velocity accuracy deteriorates due to errors between commanded and actual velocities
Solution Approach 1:
The patent implements closed-loop feedback control by using a position sensor to measure the actual position of the cutting member, comparing it to the commanded position, and adjusting motor velocity based on the error. This feedback mechanism eliminates velocity errors while maintaining manageable system complexity through standardized control circuitry.
2Manufacturing precision
If closed loop feedback control is implemented, then velocity accuracy is improved, but device complexity increases due to additional sensors and control circuits
Solution Approach 1:
A position sensor provides feedback on the actual position of the cutting member to the control circuit, which calculates velocity errors and adjusts motor commands accordingly. This feedback loop ensures high velocity accuracy while the modular design keeps complexity manageable.
Solution Approach 2:
The patent replaces complex mechanical velocity measurement systems with electronic sensing and control. Instead of using mechanical encoders or tachometers, the system uses a position sensor with electronic processing to achieve precise velocity control, simplifying the overall mechanical structure.
3Stability of the object's composition
If velocity control adjustments are made based on error terms, then tissue processing consistency is improved, but measurement precision requirements increase
Solution Approach 1:
The control circuit continuously measures velocity errors between commanded and actual cutting member motion, and adjusts motor velocity in real-time based on these errors. This feedback approach ensures consistent tissue processing by compensating for variations without requiring extremely precise measurements.
Solution Approach 2:
The system dynamically changes motor velocity parameters based on measured error terms. The control circuit adjusts velocity, acceleration, and deceleration parameters in real-time to maintain consistent cutting performance, allowing for robust tissue processing across varying conditions.
Data Source
AI summary
A surgical system comprising an end effector, a firing driver movable during a firing stroke, a motor to drive the firing driver during the firing stroke, and a control circuit is disclosed. The control circuit is to initiate the firing stroke to drive the firing driver in a first mode, wherein, in the first mode, the motor is to drive the firing driver at a first speed; detect a first motor stall condition in the first mode; transition from the first mode to a second mode based on the detected first motor stall condition, wherein, in the second mode, the motor is to drive the firing driver at a second speed less than the first speed; detect a second motor stall condition in the second mode; and pause driving the firing driver for a period of time based on the detected second motor stall condition.