Tool Tracker Calibration for Non-Symmetric Working End Orientation
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Solution Overview
Problem
Existing calibration techniques fail to provide accurate angular orientation of non-rotationally symmetric working ends of surgical tools relative to tool trackers, leading to clocking errors due to manufacturing tolerances and varying attachment forces, which can result in erroneous tool navigation and health risks.
Innovation Solution
A method and apparatus for determining the angular orientation of a non-rotationally symmetric working end of a tool part relative to a tool tracker by using a reference structure traceable by a tracked pointer, with predefined angular relation to the working end, and receiving position data to calculate the actual orientation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a tracked pointer and reference structure are used to determine angular orientation, then measurement precision is improved, but device complexity increases
Solution Approach 1:
A reference structure with known geometry is introduced as an intermediary between the tracked pointer and the working end of the tool. The reference structure serves as a mediator that allows indirect measurement of the angular orientation through pointer tracking, avoiding the need for direct complex sensors on the working end itself.
Solution Approach 2:
The reference structure acts as a geometric copy or representation of the working end's orientation characteristics. By tracking the pointer's position relative to the reference structure's known geometry, the system infers the angular orientation of the working end without directly measuring it, effectively using a simplified geometric model.
2Device complexity
If traditional calibration techniques are used, then device complexity is reduced, but measurement precision deteriorates due to inability to capture angular orientation
Solution Approach 1:
The invention replaces complex mechanical orientation sensors or multiple physical alignment procedures with a tracking-based optical/electromagnetic system. Instead of using mechanical gauges or complex alignment devices, the system uses a tracked pointer to read the position of the reference structure in 3D space, converting mechanical orientation measurement into coordinate-based calculation.
Solution Approach 2:
The invention transitions from 2D or limited-angle calibration methods to full 3D spatial tracking. By capturing the pointer's position in three-dimensional space relative to the reference structure, the system can calculate angular orientation in multiple dimensions simultaneously, providing complete angular information that traditional single-plane calibration cannot achieve.
Data Source
Figure 1A
Figure 1B~1C
Figure 2
AI summary
A technique for determining an angular orientation between a non-rotationally symmetric working end of a first part of a tool and a tool tracker carried by a second part of the tool is described. The first tool part is configured to be fixed to the second tool part in one of multiple angular orientations and comprises a reference structure. The reference structure is traceable by a tracked pointer and has a predefined angular relation to the working end. A method implementation of the technique comprises receiving first position data indicative of one or more positions of the tool tracker, receiving second position data indicative of pointer positions while the pointer is tracing the reference structure, and determining, based on the received first and second position data and the predefined angular relation between the reference structure and the working end, the angular orientation of the working end relative to the tool tracker.