Robotic Drive Control for Flexible Instrument Shaft Insertion
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Solution Overview
Problem
Existing robotic medical systems face challenges in efficiently and precisely controlling the axial motion of elongated shafts of medical instruments, particularly during procedures involving flexible tubular tools like endoscopes, due to limitations in drive mechanisms and navigation through complex anatomical pathways.
Innovation Solution
A robotic medical system incorporating a drive device attached to a second robotic arm that drives axial motion of an elongated shaft at varying rates, forming a service loop or maintaining alignment with the shaft, and utilizing rollers and a processor to manage insertion and retraction based on positional feedback.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the robotic arm moves the instrument base at a constant rate, then the positioning is simple to control, but the axial motion rate of the elongated shaft cannot be optimized independently, reducing procedural efficiency
Solution Approach 1:
The system separates the control of axial motion from the robotic arm's positioning motion. The drive device independently controls the axial motion rate of the elongated shaft, while the robotic arm handles positioning. This segmentation allows each component to optimize its function without being constrained by the other, resolving the contradiction between productivity and device complexity.
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 independently controls the axial motion rate of the shaft, enabling optimized insertion/retraction speeds without requiring the robotic arm to move at corresponding high speeds. This intermediary mechanism resolves the contradiction by decoupling the two motion control functions.
2Productivity
If the elongated shaft is driven at high speed through the access sheath, then insertion efficiency is improved, but friction and mechanical stress increase, potentially damaging the shaft or sheath
Solution Approach 1:
The drive device dynamically adjusts the axial motion rate of the elongated shaft based on real-time conditions. During insertion through the access sheath, it can reduce speed to minimize friction and mechanical stress, then increase speed when the shaft tip emerges from the sheath to improve procedural efficiency. This dynamic speed adjustment resolves the contradiction between insertion speed and harmful frictional effects.
Solution Approach 2:
The system employs periodic variation in axial motion rate, alternating between high-speed phases (when friction is minimal, such as when the shaft tip is beyond the sheath) and low-speed phases (when friction is high, such as during sheath traversal). This periodic action pattern allows the system to achieve high overall productivity while limiting peak friction and mechanical stress exposure.
3Productivity
If the drive device is positioned far from the instrument base to allow service loop formation, then high-speed axial motion is enabled, but the system requires more space and increased device complexity
Solution Approach 1:
The elongated shaft itself acts as a flexible element that forms the service loop between the drive device and the instrument base. This flexible shaft design allows the service loop to be created without additional mechanical components, reducing device complexity while enabling high-speed axial motion capability. The flexibility of the shaft accommodates the loop formation naturally during operation.
Solution Approach 2:
The elongated shaft serves multiple functions: it is both the functional instrument delivering medical tools and the flexible element forming the service loop. This multi-functionality eliminates the need for separate service loop management mechanisms, reducing device complexity while maintaining the ability to achieve high axial motion rates through service loop formation.
4Productivity
If the robotic arm moves quickly to reposition the instrument base, then navigation efficiency is improved, but synchronization with the drive device becomes difficult, reducing precision
Solution Approach 1:
The control system continuously monitors the positions of both the robotic arm and the drive device, and adjusts their motion commands to maintain synchronization. When the robotic arm moves quickly to reposition the instrument base, the feedback mechanism ensures the drive device adjusts its axial motion rate accordingly, maintaining precise coordination between the two components throughout the repositioning operation.
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
Enhances the precision and ease of navigating medical instruments through patient anatomy by allowing controlled axial motion, reducing friction, and enabling seamless transitions between insertion and retraction rates, thus improving procedural efficiency and ease of use.
Implementation Method 1
utilizing rollers and a processor to manage insertion and retraction based on positional feedback
Data Source
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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.