Underactuated Needle Steering via Continuous Rotation
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Solution Overview
Problem
Existing needle-based medical interventions face challenges in accurately guiding needles with asymmetric tips to desired targets due to deflection caused by asymmetric forces, which can result in errors in needle placement.
Innovation Solution
The system employs active, semi-autonomous control of needle insertion paths by precisely controlling the rotation of the needle as it continuously rotates during insertion, allowing for underactuated 2 degree-of-freedom control of direction and curvature from a single rotary actuator, decoupled from needle insertion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a needle with an asymmetric tip is used for insertion, then the needle can be steered by rotating the bevel direction, but the asymmetric forces cause deflection and errors in needle placement
Solution Approach 1:
The system employs a control system that continuously monitors the needle position and rotation angle, and adjusts the rotation speed dynamically to compensate for tissue deformation and maintain accurate needle placement. The feedback loop compares the actual needle position with the desired trajectory and modifies the rotation command accordingly.
Solution Approach 2:
The patent implements dynamic control of needle rotation speed that varies during insertion based on tissue properties and desired path curvature. The rotation speed is adjusted in real-time rather than being constant, allowing the system to adapt to changing tissue conditions and maintain precision throughout the insertion process.
2Ease of operation
If the needle is continuously rotated during insertion to control the path, then steering capability is improved, but control complexity increases
Solution Approach 1:
The system combines needle rotation control and insertion depth control into a single integrated control mechanism. The single rotary actuator performs both functions by varying its rotation speed, reducing the number of separate actuators and simplifying the overall control architecture while maintaining full path control capability.
Solution Approach 2:
The rotary actuator is designed to serve multiple functions: it controls both the steering direction through rotation angle and the insertion speed through rotation velocity. This multi-functional approach reduces the number of required actuators and simplifies the control system while maintaining full capability for path control.
3Manufacturing precision
If constant velocity insertion is required for accurate control, then needle placement precision is improved, but insertion flexibility is reduced
Solution Approach 1:
The system employs dynamic insertion speed control that adjusts the rotation velocity based on the desired path curvature and tissue properties. Rather than maintaining constant velocity, the system optimizes the insertion speed in real-time to achieve accurate needle placement while adapting to different tissue conditions and path requirements.
Data Source
AI summary
A needle steering system and apparatus provides active, semi-autonomous control of needle insertion paths while still enabling a clinician ultimate control over needle insertion. A method and system controls the needle path as the needle is inserted by precisely controlling the rotation of the needle as it continuously rotates during insertion. This enables underactuated 2 degree-of-freedom (DOF) control of the direction and the curvature of the needle from a single rotary actuator. Control of the rotary motion is therefore decoupled from the needle insertion. The rotary motion controls steering effort and direction, while the insertion controls needle depth or insertion speed. In one implementation, the proposed method does not require constant velocity insertion, interleaved insertion and rotation, or known insertion position or speed. The insertion may be provided by a robot or other automated method, may be a manual insertion, or may be a teleoperated insertion.