The combination of motion capture systems and medical devices can provide more comprehensive and accurate patient assessments and treatment plans to facilitate the effectiveness of rehabilitation treatment. Examples include motion analysis, surgical assistance, virtual reality rehabilitation, and biofeedback therapy.
Common types of motion capture systems:
Optical motion capture system: These systems use cameras and reflective markers to track the motion of a human body or object and reconstruct a 3D model of its movement. Typical optical motion capture systems include Vicon, OptiTrack, Qualisys, etc.
Inertial motion capture system: This system uses an inertial measurement unit (IMU) to measure the acceleration and angular velocity of the body or object and calculate its position and orientation based on the measurement results. Typical inertial motion capture systems include Xsens, MicroStrain, MoCapX, etc.
Magnetic motion capture system: This system uses magnetometers and gyroscopes to measure the motion of the body or object and calculates its position and direction based on the measurement results. Typical magnetic motion capture systems include Polhemus, Ascension, Flock of Birds, etc.
Ultrasonic motion capture system: This system uses ultrasound to measure the position and direction of the body or object for motion tracking. Ultrasonic motion capture systems are commonly used for medical applications such as motion analysis and rehabilitation. Typical ultrasonic motion capture systems include Vicon Apex, Ariel Dynamics, Qualisys Oqus, etc.
NDI Polaris Vicra system
The NDI (NaturalPoint Direct Input) Polaris Vicra system used in our project is an optical-based motion capture system developed by NaturalPoint, Inc. It is stable, accurate and easy to use, and can meet the needs of most application scenarios.
Primary components of Polaris Vicra systems
– Position Sensor
Illuminator rings provide IR source for passive tracking
– Tool Interface Unit
Controls firing of IRED markers for active tracking
– Active / Passive Markers
Active markers (IREDs) emit IR in known sequence, while passive markers reflect IR light emitted by position sensor
How does the system track tools？
1. Detecting Markers:
Measure the positions of all the visible markers. Optical tracking utilizes the principle of triangulation to locate trackable markers in space. It can be either “active” or “passive” in nature depending the type of markers
2. Acquiring Tools:
Calculate distances and angles between markers once it has matched the minimum numbers of markers
3. Tracking Tools:
Compares with marker geometry data in tool definition files to determine which markers belong to which tool.
Benefits & Costs
– Wireless tracked instrument tracking with high degree of accuracy
– Line of sight constraints