Thomas hjorth parameters meaning

Hjorth parameters are indicators of statistical properties used in signal processing in the time domain introduced by Bo Hjorth in 1970.^[1] The parameters are Activity, Mobility, and Complexity. They are commonly used in the analysis of electroencephalography signals for feature extraction.

The parameters are normalised slope descriptors (NSDs) used in EEG. Moreover, in the robotic area, the Hjorth parameters are used for tactile signal processing for the physical object properties detection such as surface textures/material detection and touch modality classification via artificial robotic skin.^[2]

Parameters

Hjorth Activity

In the activity parameter represents the signal power, the variance of a time function.

thomas hjorth parameters meaning4

This can indicate the surface of power spectrum in the frequency domain. This is represented by the following equation:

Where y(t) represents the signal.

Hjorth Mobility

The mobility parameter represents the mean Hjorth parameters - File Exchange - MATLAB Central - MathWorks KISO