Robotic Surgical Instrument Positioning With Macro-Micro Kinematics
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Solution Overview
Problem
Current robotic surgical assemblies face challenges in achieving precise kinematic control and miniaturization, with existing systems being cumbersome and requiring extensive training due to complex motion strategies and friction issues in tendon-guiding systems, limiting their versatility and precision in microsurgical procedures.
Innovation Solution
A robotic surgical assembly with a macro-positioning arm and multiple micro-positioning devices, each with motorized degrees of freedom, allows for precise translational and rotational movements, decoupling positioning and orientation within a shared workspace, and utilizing a tendon drive system with pretensioned tendons to minimize friction and enhance precision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a plurality of independent movements are coordinated for small motions of the surgical instrument, then the surgical instrument can access the operating work-field, but the control of kinematic accuracy becomes difficult and the operating work-field becomes encumbered
Solution Approach 1:
The robotic assembly is divided into two independent subsystems: a macro-positioning arm for coarse positioning and micro-positioning devices for fine adjustments. This segmentation allows each subsystem to operate independently, simplifying control while maintaining access to the operating field.
Solution Approach 2:
The macro-positioning arm acts as an intermediary between the surgeon and the surgical instrument, providing coarse positioning that brings the instrument near the target site, while micro-positioning devices handle fine adjustments. This intermediary approach reduces the complexity of direct fine control.
2Ease of operation
If joints articulating the tip of the instrument are placed further away from the tip, then the instrument can be controlled, but the encumbrance effect increases and adequate movement is not allowed
Solution Approach 1:
The control architecture transitions from spatial arrangement of joints to a hierarchical control dimension, separating macro-positioning (coarse movement) from micro-positioning (fine movement). This dimensional separation allows control mechanisms to be positioned optimally without compromising instrument tip mobility.
3Volume of moving object
If tendon-guiding systems are used for miniaturization, then the system size is reduced, but friction issues arise that limit precision
Solution Approach 1:
The tendon-guiding system is extracted from the macro-positioning arm and relocated to the micro-positioning devices near the instrument tip. This extraction allows the use of tendons only where miniaturization is critical, while larger components are positioned optimally for precision control.
4Extent of automation
If master-slave systems with mechanically linked motion recording stations are used, then teleoperation is achieved, but the learning curve is long and movement is limited
Solution Approach 1:
The system transitions from rigid mechanical linkage to a dynamic hierarchical control architecture where the macro-positioning arm and micro-positioning devices can operate independently or in coordination. This dynamic structure allows greater movement freedom and reduces the learning curve by enabling intuitive coarse positioning followed by precise adjustments.
Data Source
AI summary
A robotic surgical assembly includes a support, one macro-positioning arm, connected to the support and having a plurality of degrees of freedom. The macro-positioning arm includes a support member, at least two micro-positioning devices, each having a plurality of motorized degrees of freedom, connected in cascade to the support member of the macro-positioning arm, and at least two medical instruments. Each instrument is connected in cascade to each of the micro-positioning device and includes a jointed device having a plurality of motorized degrees of freedom including a plurality of rotational joints. Each of the at least two medical instruments has a shaft, suitable for distancing the jointed device from the micro-positioning devices by a predetermined distance in a shaft direction.