MEMS Trackable Member Orientation Calculation for Surgical Tracking
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Solution Overview
Problem
Current tracking systems in computer-assisted surgery face challenges such as the presence of wires in sterile zones, line-of-sight requirements for optical tracking, the size of trackable members affecting precision, and difficulty integrating sensors into disposable instruments like cutting guides due to volume constraints.
Innovation Solution
A computer-assisted surgery system utilizing MEMS-based trackable members with inertial sensor units connected to surgical instruments and bones, allowing for orientation data calculation and enabling tracking of three degrees of freedom using accelerometer-based reference and calibration tracking members, which are compact and wireless, reducing the need for visible markers and wires.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If active tracking systems with transmitters are used, then position and orientation data can be obtained, but wires are present in sterile zones and device complexity increases
Solution Approach 1:
The patent replaces active transmitters with passive optical reflectors, eliminating the need for wired power sources and mechanical connections in sterile zones. The passive reflectors are tracked using optical sensors that detect reflected light, substituting the active electromagnetic transmission system with a passive optical reflection system.
Solution Approach 2:
The patent extracts and removes the transmitter and power source components from the tracking system, leaving only passive optical reflectors. This extraction eliminates the harmful wires and complex power management systems while retaining the essential tracking functionality through optical detection.
2Device complexity
If passive optical tracking elements are used, then no wires are needed, but line of sight is required and surgical orientation is constrained
Solution Approach 1:
The patent arranges multiple optical reflectors in a three-dimensional configuration (e.g., tetrahedral arrangement) rather than a simple planar layout. This spatial arrangement allows the reflector assembly to be tracked from multiple angles and maintains visibility even when surgical instruments need to be oriented in different directions, adding dimensional flexibility to the tracking system.
3Measurement precision
If traditional trackable members with multiple optical elements are used, then tracking precision can be achieved, but the size is large and obstructive
Solution Approach 1:
The patent nests multiple optical reflectors within a compact three-dimensional structure where the reflectors are positioned at the vertices of a tetrahedron or similar compact polyhedron. This nested arrangement allows multiple tracking elements to occupy minimal space while maintaining their relative geometric relationships, achieving both compactness and tracking precision.
Solution Approach 2:
The patent transitions from a planar two-dimensional arrangement of reflectors to a three-dimensional spatial configuration. This dimensional change allows the same number of reflectors to be packed more efficiently in space, reducing the overall footprint and obstruction while maintaining the geometric relationships necessary for precise tracking calculations.
4Adaptability or versatility
If current optical sensors are integrated into disposable instruments, then tracking is enabled, but the volume is too large for disposable use
Solution Approach 1:
The patent replaces bulky active transmitters with compact passive optical reflectors that have no moving parts, power requirements, or electronic components. This substitution dramatically reduces the volume and complexity, making the tracking system suitable for integration into disposable surgical instruments where space and cost are critical constraints.
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
This solution provides precise, wire-free, and compact tracking of surgical instruments and bones, enhancing surgical precision and ease of use by eliminating the need for visible markers and reducing the complexity of integrating sensors into disposable instruments.
Implementation Method 1
A MEMS trackable member is used in a tracking system and comprises tracking circuitry, a transmitter, and optional confirmation indicator
Implementation Method 2
The transmitters of the active tracking systems are powered, for instance by being wired to the CAS system or by being provided with an independent power source, so as to emit signals
Implementation Method 3
The CAS system associated with passive tracking has an optical sensor apparatus provided to visually detect optical elements on the tools
Data Source
AI summary
A tracking system is provided for tracking an objects. A first and a second trackable member each have an inertial sensor unit producing at least orientation-based data. A processing unit receives the orientation-based data from the trackable members. The processing unit has an orientation calculator calculating an orientation of the second trackable member with respect to the first trackable member from the orientation-based data of both said trackable members, whereby the processing unit calculates an orientation of the objects. A method is also provided.