Surgical Tool Axis Calibration via Fiducial Marker Rotation
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Solution Overview
Problem
Current calibration methods for computer-assisted surgical systems are time-consuming, costly, and insufficiently accurate for precise surgical procedures due to inherent errors in tracking systems and manufacturing tolerances, necessitating a more efficient and accurate method to define tool tip position and orientation relative to fiducial marker arrays.
Innovation Solution
A calibration device with a rotating body and fiducial markers that generates circular paths, allowing a tracking module to calculate the tool axis orientation by averaging normal vectors from these paths, thereby improving tracking accuracy without requiring precise geometric relationships between markers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional calibration methods are used to define tool tip position and orientation relative to fiducial marker arrays, then the calibration can be performed with standard tracking systems, but the calibration time is excessive and the accuracy is insufficient for precise surgical procedures
Solution Approach 1:
The patent applies dynamics by making the fiducial marker array rotate about the tool axis during calibration, transforming a static calibration process into a dynamic one. This rotation allows the tracking system to capture multiple positions of the marker array, enabling calculation of the tool axis orientation through averaging normal vectors from multiple circular paths, thereby improving accuracy while reducing the number of manual measurement points required
Solution Approach 2:
The patent employs periodic action by rotating the fiducial marker array in a periodic manner around the tool axis. This periodic rotation generates multiple circular paths that are tracked over time, allowing the system to accumulate sufficient data points for accurate tool axis determination without requiring excessive calibration time, as the rotation naturally distributes measurements across different angular positions
2Manufacturing precision
If precise placement of fiducial marker arrays on tools is performed during factory calibration, then manufacturing precision can be improved, but the overall cost increases significantly
Solution Approach 1:
The patent replaces the mechanical precision requirement with an optical/electromagnetic tracking solution. Instead of relying on mechanically precise placement of fiducial markers during manufacturing, the system uses a tracking system to optically/electromagnetically determine the tool axis orientation by analyzing the circular paths of rotating markers, thereby eliminating the need for expensive precision manufacturing and placement
Solution Approach 2:
The patent creates a virtual model of the tool axis orientation by tracking and analyzing the circular paths of rotating fiducial markers. This virtual copying approach allows the system to determine tool orientation without requiring physical precision in marker placement, as the tracking system creates an accurate digital representation of the tool's geometric relationship to the markers
3Ease of operation
If optically-tracked digitizers are used to manually collect points on the tool for calibration, then tracking capability is provided, but the inherent error of the system and laborious digitizing process reduce overall accuracy and increase operating time
Solution Approach 1:
The patent implements self-service by allowing the rotating fiducial marker array to automatically generate the calibration data. As the marker array rotates, it self-generates multiple circular paths that are automatically tracked by the system, eliminating the need for manual digitizing operations. The system automatically calculates the tool axis orientation from the tracked paths, providing both automation and high accuracy without manual intervention
Data Source
AI summary
A calibration device is provided having a body with an exterior surface configured for placement about a tool such that the body rotates about a tool axis. One or more fiducial marker is positioned on the exterior surface and in communication with a tracking system. A fixed fiducial marker array is provided that is also in communication with the tracking system. A calibration tool defines the tool axis relative to the fiducial marker array. A surgical system is also provided with a tracking module that calculates a center point of the rotation or a normal vector to the circular path to define a tool axis orientation. A method of using the surgical system and defining a tool axis relative to a fiducial marker array is provided. A system for defining a robot link orientation or tracking a tool a medical procedure and a fiducial marker array are provided.