Variable-Velocity Surgical Instrument Control for Stall Pauses
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Minimally invasive surgical instruments with small end effectors face challenges in maintaining stiffness and consistency during grasping, clamping, and stapling operations due to limited stiffness, leading to flexing and splaying, which can result in failed or ragged velocity profiles due to tissue variations.
Innovation Solution
A surgical instrument system with a computer-assisted medical device that sets a velocity set point for the actuator, monitors force or torque, and adjusts the operation based on predefined conditions to maintain consistent velocity and torque limits, pausing or adjusting the actuator's movement to prevent excessive force and ensure successful stapling and cutting operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the end effector size is kept small for minimally invasive procedures, then the instrument can be inserted through small openings, but the end effector lacks sufficient stiffness and experiences flexing and splaying during operation
Solution Approach 1:
The patent implements variable velocity control that dynamically adjusts the actuator's speed based on real-time force feedback. When the end effector encounters tissue resistance, the system automatically reduces velocity to maintain control precision, preventing flexing and splaying while preserving the small size needed for minimally invasive access
Solution Approach 2:
The system continuously monitors force or torque applied by the actuator and uses this feedback to adjust the velocity set point. This closed-loop control ensures that the end effector maintains consistent velocity and prevents excessive force application, thereby reducing flexing and splaying during grasping, clamping, and stapling operations
2Productivity
If the actuator velocity is increased to improve surgical efficiency, then productivity increases, but the precision and control during stapling and cutting operations deteriorates
Solution Approach 1:
The system employs dynamic velocity adjustment where the actuator operates at higher speeds during non-critical phases but automatically reduces velocity during critical stapling and cutting operations. This dynamic control maintains both high productivity overall and high precision during critical tasks
Solution Approach 2:
The patent changes the velocity parameter based on the operational phase and tissue conditions. The controller adjusts the velocity set point according to force feedback, maintaining optimal speed for efficiency while ensuring sufficient control precision during stapling and cutting operations
3Reliability
If the force applied by the actuator is increased to ensure successful stapling and cutting, then the reliability of the operation improves, but the risk of tissue damage and instrument flexing increases
Solution Approach 1:
The system uses real-time force feedback to monitor the load on the actuator and adjusts velocity accordingly. This ensures sufficient force is applied for reliable stapling and cutting while preventing excessive force that could cause tissue damage or instrument flexing
Solution Approach 2:
The variable velocity control proactively prevents excessive force application by reducing speed when force thresholds are approached. This preliminary anti-action prevents tissue damage and instrument flexing before they occur, while still ensuring adequate force for successful stapling and cutting
Data Source
AI summary
Techniques for control of an instrument include a device having an actuator. To perform an operation with an instrument coupled to the actuator, the instrument is operated according to a state machine by: transitioning the instrument from a gripped state to a clamped state in response to receiving a clamp command; transitioning the instrument from the clamped state to a firing state in response to receiving a fire command; transitioning the instrument from the firing state to a pause state in response to detecting a stall in the actuator used to actuate the instrument; transitioning the instrument from the pause state to a stop firing state in response to a pause limit being reached; and transitioning the instrument from the pause state to the firing state in response to the actuator beginning to move again or after a first predetermined period of time has elapsed since entering the pause state.