Roller Axial Shaft Drive for Fast Robotic Instrument Insertion
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Solution Overview
Problem
Current robotic medical systems face limitations in efficiently driving axial motion of elongated shafts during medical procedures, particularly in achieving high insertion and retraction speeds, overcoming shaft buckling, and ensuring controlled force application within the patient's tissue.
Innovation Solution
The system incorporates a drive device with a pair of opposing rollers and a channel configuration that allows for axial motion of the elongated shaft, enabling faster insertion and retraction rates and reducing buckling by applying force closer to the insertion point, while maintaining a controlled force through the use of a service loop mechanism.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a robotic arm directly drives axial motion of the elongated shaft, then the movement rate is limited by the robotic arm's speed, but the system complexity is reduced
Solution Approach 1:
The system segments the axial motion drive function from the robotic arm by introducing a dedicated drive device with rollers. The robotic arm provides positioning while the drive device independently handles high-speed axial insertion and retraction, allowing each component to optimize its function without being constrained by the other's speed limitations.
Solution Approach 2:
The drive device acts as an intermediary between the robotic arm and the elongated shaft. It receives positioning commands from the robotic arm and translates them into controlled axial motion through the roller mechanism, enabling speed enhancement while maintaining system coordination.
2Speed
If force is applied at the distal end of the shaft for insertion, then insertion speed is maximized, but shaft buckling occurs
Solution Approach 1:
The system introduces a service loop that creates a dimensional buffer between the drive device and the shaft insertion point. This loop allows the shaft to maintain stability at the insertion point while the drive device operates independently, decoupling the speed optimization from the stability constraint.
Solution Approach 2:
The service loop acts as a mechanical intermediary that transmits force from the drive device to the shaft while maintaining shaft stability. It allows force application at the drive device location rather than directly at the distal end, preventing buckling while enabling high-speed insertion.
3Loss of time
If the shaft is moved rapidly for high insertion rates, then procedure time is reduced, but tissue force application increases
Solution Approach 1:
The system segments the motion control into two independent functions: the robotic arm controls positioning and speed timing, while the drive device controls force application through the roller mechanism. This allows rapid shaft movement during insertion while maintaining controlled, limited force at the tissue interface.
Solution Approach 2:
The roller-based drive device changes the force transmission parameter by providing controlled friction engagement rather than direct mechanical coupling. This allows high-speed motion while limiting the force transmitted to the tissue, as the rollers can slip or adjust engagement to prevent excessive force application.
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
This configuration allows for increased insertion and retraction speeds, reduced procedure time, and minimized tissue force application, enhancing both patient outcomes and operational efficiency.
Implementation Method 1
a drive device with a pair of opposing rollers and a channel configuration that allows for axial motion of the elongated shaft
Data Source
AI summary
Certain aspects relate to systems and techniques for driving axial motion of a shaft of a medical instrument using a drive device. A robotic medical system can include a drive device comprising a pair of rollers configured to engage a shaft of a medical instrument and a processor configured to operate the rollers to drive insertion of the shaft at a first rate during a first insertion period when a distal tip of the shaft is positioned within an access sheath inserted into the patient, and operate the rollers to transition to driving insertion of the shaft at a second rate that is slower than the first rate during a second insertion period when the distal tip of the shaft is positioned beyond a distal tip of the access sheath.