L18 - motion capture

Question 2

What are common reasons to perform biomechanical analysis?

Answer 2

1. Understand the skill (generally or specifically)
2. Assess performance or injury risk
3. Evaluate training effects or specificity
4. Analyse movement variability

Question 3

What are marker-based motion capture systems?

Answer 3

High-accuracy systems using physical markers

Require expensive equipment and lab-based setup

Often lack ecological validity due to non-natural setting

Question 4

What is pose detection in biomechanics?

Answer 4

AI-based detection of body keypoints from images or video, similar to facial recognition.

Question 5

What is OpenCap?

Answer 5

A pose detection system that estimates anatomical features from detected body keypoints using video-based motion analysis.

Question 6

How does OpenCap differ from traditional motion capture?

Answer 6

OpenCap uses video and AI instead of physical markers

It’s more accessible and can be used outside a lab

Question 7

What are the key types of kinematic quantities in biomechanics?

Answer 7

Linear Kinematics:
Scalars: position (s), distance (d), speed (v), acceleration (a)

Vectors: displacement (d), velocity (v), acceleration (a)

Angular Kinematics:
Angle (θ), angular displacement (∆θ), angular velocity (ω), angular acceleration (α)

Question 8

What is segmentation in biomechanical data processing?

Answer 8

Dividing motion data into meaningful chunks (e.g., strides or phases) based on events.

Question 9

Why can segmentation be difficult with kinematic data alone?

Answer 9

Kinematic data may not clearly indicate specific events unless paired with force data or clear motion patterns.

Question 10

What type of model is typically combined with mocap data?

Answer 10

A musculoskeletal model, used to estimate joint loads, muscle forces, or movement dynamics.