Surgical End Effector Articulation Velocity Control by Position Feedback
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Solution Overview
Problem
Existing motorized surgical stapling and cutting instruments face challenges in controlling the articulation velocity of the end effector, leading to undesired variations near the end of the stroke or during removal from a trocar, which can affect user control and tissue handling.
Innovation Solution
A surgical instrument with a sensor to detect the articulation position of the end effector and a control circuit to provide a drive signal to the motor, ensuring the end effector moves at a velocity corresponding to its position, thereby maintaining consistent articulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a motor drives the end effector between unarticulated and articulated positions, then the end effector can articulate between positions, but the articulation velocity varies undesirably near the end of stroke and during removal from trocar
Solution Approach 1:
The control circuit receives feedback from the sensor about the articulation position and adjusts the motor drive signal duty cycle accordingly. This closed-loop feedback system allows the articulation velocity to be controlled as a function of the end effector articulation angle, preventing undesired velocity variations near the end of stroke and during trocar removal.
Solution Approach 2:
The system dynamically adjusts the motor drive signal duty cycle based on the articulation angle. By varying the duty cycle as a function of position, the articulation velocity is controlled to maintain consistency throughout the range of motion, particularly addressing the velocity variations that occur at extreme positions.
2Productivity
If the end effector articulation velocity is not controlled, then the system is simpler, but the sweep rate varies undesirably in areas of interest
Solution Approach 1:
The control circuit uses feedback from the sensor to continuously monitor articulation position and adjust the motor drive signal duty cycle. This feedback mechanism ensures consistent sweep rate across different articulation positions while maintaining a relatively simple overall system architecture.
Solution Approach 2:
The system changes the parameter being controlled from constant velocity to position-dependent velocity. By controlling articulation velocity as a function of articulation angle rather than maintaining constant velocity, the system achieves consistent sweep rate performance without requiring complex mechanical mechanisms.
3Manufacturing precision
If a sensor and control circuit are added to control articulation velocity, then precise velocity control is achieved, but the device complexity increases
Solution Approach 1:
The system replaces complex mechanical velocity control mechanisms with an electrical control approach. By using a sensor to detect position and a control circuit to adjust the motor drive signal duty cycle, precise velocity control is achieved through electrical means rather than mechanical design, simplifying the overall system while maintaining precision.
Data Source
AI summary
A motorized surgical instrument is disclosed. The surgical instrument includes a motor configured to drive an end effector between an unarticulated position and an articulated position, a sensor configured to detect a position of the end effector and provide a signal indicative of the position of the end effector, and a control circuit coupled to the sensor and the motor. The control circuit is configured to detect a position of the end effector via the signal provided by the sensor and provide a drive signal to the motor to drive the end effector at a velocity corresponding to the signal indicative of the position of the end effector.