Robotic Shaft Drive Rollers for Fast Insertion Without Buckling
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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 and depths, while minimizing shaft buckling and tissue force, due to constraints in robotic arm movement and shaft alignment.
Innovation Solution
A robotic medical system with a drive device that includes a pair of rollers and a channel to engage the elongated shaft, allowing for axial motion control through a service loop mechanism, where the rollers rotate to insert or retract the shaft, and a clip to attach to an access sheath, enabling faster motion rates than the robotic arm and reducing buckling by applying force closer to the insertion point.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the robotic arm moves the instrument base at a limited speed, then the system maintains simplicity and reliability, but the insertion and retraction speed of the elongated shaft is constrained
Solution Approach 1:
A drive device acts as an intermediary mechanism between the robotic arm and the elongated shaft. The drive device includes a drive member with a channel that receives the shaft, and a roller that contacts the shaft to drive axial motion. This intermediary allows the shaft to move faster than the robotic arm by creating and managing a service loop of shaft between the instrument base and the drive device.
Solution Approach 2:
The system dynamically manages the service loop of the elongated shaft, allowing the shaft to buckle and form loops during high-speed insertion and retraction. The drive device can tolerate and manage this dynamic configuration, enabling speeds greater than the robotic arm movement rate. The service loop length changes dynamically during operation to accommodate the speed differential.
2Stability of the object's composition
If the drive device applies force farther from the insertion point, then the system structure is simpler, but shaft buckling increases during high-speed insertion and retraction
Solution Approach 1:
The drive device is positioned at a different spatial location (distal to the instrument base) than traditional drive mechanisms. This spatial repositioning allows the drive device to apply force closer to the insertion point in terms of effective leverage, reducing shaft buckling. The service loop configuration in the spatial dimension between the drive device and instrument base enables this improved force application geometry.
3Speed
If the robotic arm moves faster to increase insertion speed, then the insertion and retraction speed improves, but the precision of shaft alignment and control deteriorates
Solution Approach 1:
The system uses dynamic service loop management to decouple the speed of the robotic arm from the speed of the shaft insertion. The service loop acts as a dynamic buffer that absorbs speed differentials and maintains shaft alignment. During high-speed operation, the loop configuration changes dynamically to maintain proper shaft orientation and alignment precision.
Solution Approach 2:
The drive device serves as a precision intermediary that maintains shaft alignment during high-speed operation. The channel in the drive member and the roller contact point provide a controlled interface that guides the shaft, ensuring proper alignment even when the shaft is moving faster than the robotic arm can physically move the instrument base.
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 enables faster insertion and retraction speeds, increased insertion depth, and reduced shaft buckling, while maintaining a safe force on patient tissue, improving procedural efficiency and patient outcomes.
Implementation Method 1
a drive device that includes a pair of rollers and a channel to engage the elongated shaft, allowing for axial motion control through a service loop mechanism, where the rollers rotate to insert or retract the 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. Axial motion can include insertion and/or retraction of the instrument. For example, a robotic medical system can include a medical instrument comprising an instrument base and a flexible shaft configured for insertion into a patient, and a first robotic arm attachable to the instrument base of the medical instrument. The system also includes a drive device configured to engage the flexible shaft, and a second robotic arm attachable to the drive device. The second robotic arm is configured to operate the drive device to drive axial motion of the flexible shaft, and the first robotic arm is configured to move in coordination with operation of the drive device.