Automatic Calibration of Acceleration Data Using GGIR

Cicada has implemented an algorithm adapted from the GGIR package to automatically calibrate acceleration data.

Note

Reference: Van Hees, Vincent T., et al. “Autocalibration of accelerometer data for free-living physical activity assessment using local gravity and temperature: an evaluation on four continents.” Journal of Applied Physiology 117.7 (2014): 738-744.

First, the algorithm aims to find data segments where there is (almost) no change in movement, i.e. where the standard deviation in the x, y, and z component of acceleration is less than sdCriterion = 0.013. Then, the algorithm assumes that the mean acceleration for these stationary segments must be 1 g. Finally, the algorithm iteratively finds the new offset and gain factors for each acceleration direction such that its deviation from 1 g is minimized.

Please refer to the section ‘Autocalibration method’ with the methods section of the reference paper above for full details on this algorithm.

To autocalibrate the acceleration data using GGIR,

• click Preprocess > GGIR Automatic Calibration.