What is Inertial Measurement Unit (IMU) Based Motion Capture?
Inertial Measurement Unit (IMU) motion capture: Inertial motion capture employs miniature sensors that contain accelerometers, gyroscopes, and magnetometers to measure human motion. Unlike other motion capture systems (such as camera-based system), IMU mocap is portable and can be used everywhere, hence it is becoming more and more popular in many different fields.
How Does It Work?
Inertial measurement units (IMU) are mounted on various parts of the body. Each of these sensors measures its own orientation and acceleration and via the usage of complex algorithms the individual values are fused to form a full digital 3D representation of the wearers’ movements.
Components of IMU Motion Capture
Accelerometers
Measuring linear acceleration in 3D space, sensing motion and tilt with respect to gravity
Gyroscopes
Measure rotational motion about three axes, offering high accuracy orientation information
Magnetometers
As digital compasses to identify heading with respect to Earth’s magnetic field.
Sensor Fusion
Advanced algorithms help fuse data from all sensors together to deliver accurate orientation estimates.
How Does IMU Motion Capture Work?
Sensor Placement
Miniature IMU sensors attach to several parts of the body via straps or special suits.
Data Collection
Each sensor continuously measures acceleration, angular rates and magnetic field quantities at high rates.
Data Transmission
Data collected with sensors is sent wirelessly to a central processing unit in real time or captured and analyzed later.
Sensor Fusion
Advanced algorithms use information from all sensors to piece together a full-body motion in 3D space.
Applications of IMU Motion Capture
Film & Animation
Developing realistic character animations without the need for expensive camera rigs.
Video Games
Realtime motion tracking for immersive gaming applications
Healthcare
Walking analysis and progress monitoring for patients in rehabilitation
Sports Science
Athlete technique analysis and technique optimisation
Advantages Over Optical Systems
| Feature | IMU Motion Capture | Optical Motion Capture |
|---|---|---|
| Portability | Highly portable | Fixed installation |
| Environment | Any environment | Controlled studio |
| Setup Time | Minutes | Hours |
| Cost | Lower cost | Expensive |
| Accuracy | Good (drift issues) | Excellent |
Future Trends
There are some really interesting breakthroughs coming down the line that will move the IMU motion capture a little farther forward than it was before:
AI Enhancement
Machine learning algorithms will fine tune to increase accuracy and make up for drift.
Biometric Integration
Integrating motion measurements with physiological measurements for whole body analysis.
AR/VR Integration
Complete integration with augmented and virtual reality environments.
Telemedicine
Motion tracking to guide rehabilitation, physical therapy and remote patient monitoring.
Conclusion
The cost-effective IMU-based motion capture technology has unleashed motion tracking technology for a whole new set of applications beyond traditional studio shooting. While there are still challenges to overcome, such as sensor drift (learn more about IMU drift causes and solutions), there are ongoing developments in sensor technology and algorithms that are helping to make them more accurate and reliable. As the technology continues to mature and prices drop, we can look forward to seeing IMU motion capture systems become an ubiquitous technology for healthcare, sports, entertainment, and many other fields.
You also can learn more about how to build a motion capture suit.