Mechanically Decoupled Catheter Actuation for Precise Steering
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Solution Overview
Problem
Existing robotic systems for controlling medical catheters, such as intra-cardiac echocardiography (ICE) catheters, face challenges in providing precise control over catheter orientation and are prone to buckling due to their mechanical design and large footprint, making them difficult to sterilize and use in clinical settings.
Innovation Solution
A mechanically decoupled robotic catheter system with independent control of handle rotation and knob steering, utilizing multiple motors and gearing to allow precise positioning and alignment of the catheter, with a compact and modular base design that maintains sterility and allows for flexible access points.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a robotic system controls multiple degrees of freedom of the ICE catheter simultaneously, then the cognitive strain on the user is reduced, but the device complexity increases
Solution Approach 1:
The robotic control system is segmented into independent modules: a base unit with motors and a movable arm with joints. Each joint and motor represents an independent degree of freedom that can be controlled separately, allowing the system to manage multiple catheter DOFs without overwhelming complexity in a single control unit.
Solution Approach 2:
The system transitions from a fixed, handle-based control to a movable arm that operates in three-dimensional space. The arm's joints provide rotational and translational capabilities, adding spatial dimensions to the control mechanism. This dimensional expansion allows sophisticated multi-DOF control while distributing complexity across multiple physical axes rather than concentrating it in a single interface.
2Adaptability or versatility
If the robotic system uses a large footprint design, then it provides comprehensive control capabilities, but it becomes difficult to sterilize and use in clinical settings
Solution Approach 1:
The robotic system is divided into separable components: a base unit and a movable arm that can be detached. This segmentation allows the arm, which contacts the catheter, to be easily sterilized or disposed of, while the base unit with electronics can be reused without full sterilization. Each segment can be optimized for its specific requirements.
Solution Approach 2:
The movable arm and its components can be designed as disposable elements that are discarded after a single use or sterilization cycle, eliminating the need to sterilize complex electronic components. This approach maintains comprehensive control capabilities while solving the sterilization challenge by replacing rather than reprocessing critical parts.
3Device complexity
If all motions are done at the handle far from the insertion point, then the control mechanism is simplified, but catheter buckling occurs
Solution Approach 1:
The control mechanism extends from the handle into three-dimensional space using a movable arm with multiple joints. Instead of all control actions occurring at the handle, the arm positions itself in space to apply forces and torques at various points along the catheter. This spatial distribution of control actions prevents buckling by maintaining proper catheter alignment throughout its length.
Solution Approach 2:
The movable arm acts as an intermediary between the base control unit and the catheter. It translates rotational motions at the base into precise positional adjustments at the catheter's access point. This intermediate mechanical structure distributes control forces along the catheter's length, preventing buckling while maintaining control sophistication.
4Measurement precision
If the robotic system provides precise control of catheter orientation, then imaging quality is improved, but the mechanical design becomes more complex
Solution Approach 1:
Orientation control is segmented across multiple independent joints in the movable arm. Each joint provides rotational freedom about a specific axis, and the combination of these segmented rotational controls achieves precise three-dimensional orientation of the catheter. This segmentation distributes the precision requirement across multiple simple rotational mechanisms rather than requiring a single complex positioning system.
Solution Approach 2:
The movable arm employs dynamic positioning with multiple degrees of freedom, allowing the system to achieve precise catheter orientation through coordinated motion of several joints. Rather than relying on a single static mechanical linkage, the dynamic multi-joint arm can adapt its configuration to achieve the desired orientation, simplifying each individual joint while maintaining overall precision.
Data Source
AI summary
For robotically operating a catheter, a medical catheter is controlled by rotation of the catheter as well as steering in one or more planes of a distal end of the catheter. To robotically rotate the catheter, a handle is rotated. The steering is performed separately using one or more knobs on the handle. The rotation of the handle complicates the robotic control of the knob. A mechanical decoupling is used so that rotation of the handle maintains the position of the knob relative to the handle. Gearing or transmission is used to avoid independent control of the knob and handle rotation. In an alternative or additional approach, the handle may be robotically controlled while also guiding the catheter shaft spaced away from the handle, allowing fine-tuned control of the catheter at the access point to the patient.