Hip Extension

Measure and train left or right hip extension angle during walking or daily movement.

Nodes Required: 4

• Sensing (2):

  • pelvis (back center, switch pointing up)

  • thigh (left or right lateral, switch pointing up)

• Feedback (2):

  • feedback_min

  • feedback_max

Algorithm & Calibration

Algorithm Information

The app uses quaternion data from IMUs to calculate 3D joint angles. The orientation is converted into XYZ Euler angles, from which the sagittal plane (hip extension) angle is extracted. This angle reflects relative rotation between the thigh and pelvis segments.

Calibration Process

On the first iteration, the app aligns sensor orientation to body segment alignment:

• Calculates yaw offset between pelvis and thigh

• Applies this alignment to correct global measurements

• Uses predefined target orientation as a reference

Description of Data in Downloaded File

Calculated Fields

• time (sec): time since trial start

• Hip_ext (deg): hip flexion/extension angle

• Feedback_min: minimum threshold used for feedback

• Feedback_max: maximum threshold used for feedback

Sensor Raw Data Values

Please Note: Each of the columns listed below will be repeated for each sensor

• SensorIndex: index of raw sensor data

• AccelX/Y/Z (m/s^2): raw acceleration data

• GyroX/Y/Z (deg/s): raw gyroscope data

• MagX/Y/Z (μT): raw magnetometer data

• Quat1/2/3/4: quaternion data (Scaler first order)

• Sampletime: timestamp of the sensor value

• Package: package number of the sensor value