Inertial Joint Motion Tracking via Sensor Fusion
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Solution Overview
Problem
Conventional motion tracking systems for human body motion are bulky, costly, and lack the necessary accuracy and dynamic range for clinical diagnostics, often requiring radiation-based imaging and trained technicians, which are impractical and pose health risks.
Innovation Solution
A joint monitoring apparatus combining inertial monitoring units with ultrasound technology for wireless, real-time tracking of joint motion, using inertial sensors, vibration detection, and pulse echo ultrasound to determine bone positions without external references, facilitating accurate and cost-effective monitoring.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional motion tracking systems use ionizing radiation to image the patient, then motion data can be captured, but adverse health effects occur due to radiation exposure
Solution Approach 1:
The patent replaces ionizing radiation-based imaging systems with inertial measurement units (IMUs) that use mechanical sensors (accelerometers, gyroscopes, magnetometers) to detect motion. This substitution eliminates radiation exposure while maintaining motion tracking capability through direct mechanical measurement of acceleration and orientation changes.
Solution Approach 2:
The patent introduces inertial sensors as intermediary devices between the patient's body motion and the data collection system. These sensors attach directly to body segments and transduce mechanical motion into electrical signals, serving as a non-radiative mediator that captures motion data without exposing the patient to harmful radiation.
2Adaptability or versatility
If conventional motion tracking systems are made available in hospital settings, then motion data can be collected for diagnosis, but the systems are bulky and require specially-trained technicians
Solution Approach 1:
The patent divides the motion tracking system into separate, modular inertial measurement units that can be independently attached to different body segments. Each unit contains its own sensors and processing capability, allowing the system to be distributed across multiple small components rather than requiring a single bulky centralized system, thereby improving portability and ease of use in clinical settings.
Solution Approach 2:
The inertial measurement units are designed to be self-contained with integrated sensors, processors, and power sources, eliminating the need for complex external infrastructure or specially-trained technicians for operation. The units autonomously collect, process, and transmit motion data, making the system easy to deploy and use in routine clinical practice without requiring specialized technical expertise.
3Device complexity
If MEMS-based IMUs are used to miniaturize the system, then portability improves, but static accuracy is limited to about 0.4 degrees in orientation
Solution Approach 1:
The patent combines multiple types of inertial sensors (accelerometers, gyroscopes, and magnetometers) within each IMU unit to create a complementary sensor fusion system. This merging of different sensing modalities allows the miniaturized system to achieve higher overall accuracy than any single sensor type could provide alone, overcoming the limitations of MEMS-based orientation measurement while maintaining small size.
Solution Approach 2:
The patent employs a composite sensing approach by integrating multiple sensor technologies (accelerometric, gyroscopic, magnetometric) into a unified IMU system. This composite sensor architecture leverages the strengths of each sensor type to compensate for individual weaknesses, achieving improved measurement precision despite the miniaturized form factor of individual MEMS components.
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
Enables precise, real-time, and cost-effective in-vivo tracking of human joint motion with high mobility, avoiding radiation exposure and the need for specialized technicians, thus improving diagnostic capabilities.
Implementation Method 1
IMUs are configured to detect motion based on the effects of acceleration on a sensor. Generally, an IMU includes multiple inertial measuring sensors, such as accelerometers and/or gyroscopes that allow the position of the IMU to be determined without an external reference.
Data Source
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AI summary
Systems, apparatus, and method of monitoring a position of a joint. An inertial monitoring unit (48A) is configured to be coupled to a portion of a patient, such as a thigh (26). Another inertial monitoring unit (48B) is configured to be attached to another portion of the patient, such as a shank (24), that is connected to the other portion by a joint, such as a joint (28). The inertial monitoring units (48A, 48B) detect motion of their respective portions of the patient and transmit data indicative of this motion. These transmissions may be received by a computer (54) and used to determine an orientation of the joint (28). The inertial monitoring units (48A, 48B) may also be coupled to vibration detection modules (50) and/or ultrasound modules (52) that provide additional data regarding a condition of the joint (28).