Robotic Surgical Closure Velocity Control via PID Feedback
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Solution Overview
Problem
Robotic surgical systems face challenges in accurately measuring tissue thickness and adjusting cutting and stapling speeds to handle varying tissue types, leading to inconsistent surgical outcomes.
Innovation Solution
A control system with sensors and feedback mechanisms, including strain gauges and magnetic field sensors, measures tissue thickness and force, allowing for real-time adjustments in cutting and stapling speeds to optimize surgical precision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a motorized robotic surgical stapling and cutting instrument is used to measure position and velocity over an initial predetermined time or displacement to control speed, then tissue thickness evaluation and speed adjustment capability are improved, but device complexity increases due to additional sensors and control mechanisms
Solution Approach 1:
The patent implements feedback control by measuring the position and velocity of the cutting member over an initial predetermined time or displacement, comparing these measurements against threshold values, and using this feedback to adjust the speed of the remaining stroke. This closed-loop control system enables real-time adaptation to tissue thickness variations while maintaining systematic control architecture.
Solution Approach 2:
The system performs preliminary measurement of tissue thickness by evaluating position and velocity data during an initial predetermined time or displacement period before the main cutting stroke. This preliminary action allows the control system to pre-determine appropriate speed adjustments for the remaining stroke, improving measurement precision without requiring complex real-time calculations during the critical cutting phase.
2Object-affected harmful factors
If the controller is programmed to operate in slow mode when measured force reaches a predetermined level, then tissue damage is reduced, but surgical productivity decreases due to slower operation speed
Solution Approach 1:
The patent implements dynamic speed adjustment by programming the controller to automatically switch between normal operating speed and slow mode based on real-time force measurements. When the measured force reaches a predetermined level indicating vulnerable tissue, the system dynamically reduces speed to minimize damage. This dynamic adaptation allows the system to maintain high productivity during normal operations while providing protective slow mode when needed, resolving the contradiction between tissue safety and surgical throughput.
Solution Approach 2:
The system changes the operating parameter (speed) based on measured force conditions. By monitoring force levels and adjusting the motor speed parameter accordingly - maintaining high speed for normal tissue and switching to slow mode when force thresholds are exceeded - the system optimizes both tissue protection and surgical efficiency without requiring manual intervention.
3Manufacturing precision
If PID control feedback loop mechanisms are used to measure specified variables and adjust control variables, then control precision is improved, but device complexity and computational requirements increase
Solution Approach 1:
The patent employs PID control feedback loop mechanisms that continuously measure specified variables (position, velocity, force) and adjust control variables (motor commands) based on the difference between measured and target values. This feedback approach improves cutting and stapling precision by compensating for variations in tissue properties and mechanical system dynamics, while the modular implementation keeps control mechanism complexity manageable.
Solution Approach 2:
The system replaces manual mechanical control with automated electronic PID control mechanisms. By using electronic sensors and controllers to measure and adjust operating parameters, the system achieves higher precision than manual mechanical adjustment would allow, while reducing the complexity of mechanical linkages and manual control interfaces.
4Measurement precision
If real-time measurement and adjustment mechanisms are implemented to adapt to varying tissue types, then surgical accuracy is improved, but procedural time increases due to additional measurement and adjustment steps
Solution Approach 1:
The system performs preliminary measurements of tissue thickness and properties during an initial predetermined time period before the main surgical procedure. By acquiring and processing measurement data in advance, the system establishes baseline parameters that enable real-time adjustments without adding significant time during the critical surgical phases, thus improving accuracy while minimizing time loss.
Solution Approach 2:
The patent implements continuous real-time measurement and adjustment mechanisms that operate throughout the surgical procedure without interrupting the workflow. The system continuously monitors position, velocity, and force parameters, making automatic adjustments as needed, thereby maintaining high surgical accuracy without requiring discrete time-consuming measurement and adjustment steps that would break the continuity of useful action.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The system ensures precise control over cutting and stapling, improving surgical accuracy and efficiency by adapting to different tissue types, reducing tissue damage and procedural time.
Implementation Method 1
A control system with sensors and feedback mechanisms, including strain gauges and magnetic field sensors, measures tissue thickness and force
Implementation Method 2
A control system with sensors and feedback mechanisms, including strain gauges and magnetic field sensors, measures tissue thickness and force
Data Source
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AI summary
A robotic control system for a surgical system includes a control system, a control circuit, and a proportional, integral, derivative (PID) feedback control system. The control circuit determines actual closure force of a closure member, compares the actual closure force to a threshold, determines a set point velocity to displace the closure member based on the comparison, and controls the actual velocity of the closure member based on the set point velocity. A force sensor measures the closure force. A threshold closure force includes upper and lower thresholds. The set point velocity is configured to advance the closure member distally when the actual closure force is less than the lower threshold. The set point velocity is configured to retract the closure member proximally when the actual closure force is greater than the lower threshold.