Surgical Stapler Motor Velocity Control via Articulation Angle Feedback
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Solution Overview
Problem
Motorized surgical stapling and cutting instruments face challenges in maintaining consistent articulation velocity and preventing undesired articulation due to externally applied loads, which can affect tissue handling and surgical precision.
Innovation Solution
The surgical instrument incorporates a control circuit with a motor drive system and position sensors to control the articulation of the end effector, allowing for precise control of the cutting member's velocity and preventing unwanted articulation through a clutch assembly and dynamic motor braking system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the end effector is articulated at constant velocity, then tissue handling smoothness is improved, but control precision deteriorates when external loads are applied
Solution Approach 1:
The system transitions from constant velocity control to dynamic velocity control where the motor velocity is adjusted based on the current articulation angle. The control circuit modifies velocity commands in real-time to compensate for external loads, maintaining both smooth tissue handling and stable control precision throughout the articulation range.
Solution Approach 2:
The control circuit continuously monitors the articulation angle and uses this feedback to adjust the motor velocity commands. By comparing the actual articulation state with the desired state, the system dynamically modifies velocity to maintain control stability under varying external loads while preserving smooth articulation motion.
2Device complexity
If the end effector articulation is left uncontrolled, then device complexity is reduced, but harmful external load effects increase
Solution Approach 1:
The system replaces complex mechanical braking mechanisms with an electronic control solution. The control circuit uses motor control to actively prevent undesired articulation movement, achieving the same protective function with reduced mechanical complexity. The motor controller acts as an electronic brake, providing precise control without additional mechanical components.
3Productivity
If motor velocity is increased to improve productivity, then surgical efficiency is improved, but tissue handling precision deteriorates
Solution Approach 1:
The system implements dynamic velocity adjustment based on articulation angle, allowing high velocities during portions of the stroke where precision is less critical and reducing velocities where precise tissue handling is required. This enables both high productivity and high precision to be achieved at different phases of the articulation cycle.
Data Source
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AI summary
A motorized surgical instrument is disclosed. The surgical instrument includes a control circuit configured to control the movement of an end effector. If the end effector moves outside a predetermined acceptable range, the control circuit may create a dynamic brake to resist the undesired movement of the end effector. The control circuit may apply pulse width modulated (PWM) current to resist the undesired movement of the end effector outside a predetermined acceptable range.