As excerpted from README.txt in UCI HAR Dataset:
The experiments have been carried out with a group of 30 volunteers within an age bracket of 19-48 years. Each person performed six activities (WALKING, WALKING_UPSTAIRS, WALKING_DOWNSTAIRS, SITTING, STANDING, LAYING) wearing a smartphone (Samsung Galaxy S II) on the waist. Using its embedded accelerometer and gyroscope, we captured 3-axial linear acceleration and 3-axial angular velocity at a constant rate of 50Hz. The experiments have been video-recorded to label the data manually. The obtained dataset has been randomly partitioned into two sets, where 70% of the volunteers was selected for generating the training data and 30% the test data.
The sensor signals (accelerometer and gyroscope) were pre-processed by applying noise filters and then sampled in fixed-width sliding windows of 2.56 sec and 50% overlap (128 readings/window). The sensor acceleration signal, which has gravitational and body motion components, was separated using a Butterworth low-pass filter into body acceleration and gravity. The gravitational force is assumed to have only low frequency components, therefore a filter with 0.3 Hz cutoff frequency was used. From each window, a vector of features was obtained by calculating variables from the time and frequency domain.
Subject of measurement. Subject ID may come from either test or training data set.
Textual description of data set. Description obtained from activity_labels.txt in UCI HAR Dataset.
- WALKING
- WALKING_UPSTAIRS
- WALKING_DOWNSTAIRS
- SITTING
- STANDING
- LAYING
The following variables represent means of all measurements for that subject & activity combination across the measured data sets.
The features selected for this database come from the accelerometer and gyroscope 3-axial raw signals tAcc-XYZ and tGyro-XYZ. These time domain signals (prefix 't' to denote time) were captured at a constant rate of 50 Hz. Then they were filtered using a median filter and a 3rd order low pass Butterworth filter with a corner frequency of 20 Hz to remove noise. Similarly, the acceleration signal was then separated into body and gravity acceleration signals (tBodyAcc-XYZ and tGravityAcc-XYZ) using another low pass Butterworth filter with a corner frequency of 0.3 Hz.
Body acceleration measurements separated with a low pass Butterworth filter with a corner frequency of 0.3Hz.
Mean of time domain means of adjusted body acceleration from accelerometer captured at a constant rate of 50 Hz in Z dimension. Raw measurements were filtered using a median filter and a 3rd order low pass Butterworth filter with a corner frequency of 20 Hz to remove noise, then separated using another low pass Butterworth filter with a corner frequency of 0.3 Hz.
Mean of time domain means of adjusted body acceleration from accelerometer captured at a constant rate of 50 Hz in Y dimension. Raw measurements were filtered using a median filter and a 3rd order low pass Butterworth filter with a corner frequency of 20 Hz to remove noise, then separated using another low pass Butterworth filter with a corner frequency of 0.3 Hz.
Mean of time domain means of adjusted body acceleration from accelerometer captured at a constant rate of 50 Hz in Z dimension. Raw measurements were filtered using a median filter and a 3rd order low pass Butterworth filter with a corner frequency of 20 Hz to remove noise, then separated using another low pass Butterworth filter with a corner frequency of 0.3 Hz.
Mean of time domain standard deviations of adjusted body acceleration from accelerometer captured at a constant rate of 50 Hz in X dimension. Raw measurements were filtered using a median filter and a 3rd order low pass Butterworth filter with a corner frequency of 20 Hz to remove noise, then separated using another low pass Butterworth filter with a corner frequency of 0.3 Hz.
Mean of time domain standard deviations of adjusted body acceleration from accelerometer captured at a constant rate of 50 Hz in Y dimension. Raw measurements were filtered using a median filter and a 3rd order low pass Butterworth filter with a corner frequency of 20 Hz to remove noise, then separated using another low pass Butterworth filter with a corner frequency of 0.3 Hz.
Mean of time domain standard deviations of adjusted body acceleration from accelerometer captured at a constant rate of 50 Hz in Z dimension. Raw measurements were filtered using a median filter and a 3rd order low pass Butterworth filter with a corner frequency of 20 Hz to remove noise, then separated using another low pass Butterworth filter with a corner frequency of 0.3 Hz.
Gravity acceleration measurements separated with a low pass Butterworth filter with a corner frequency of 0.3Hz.
Mean of time domain means of adjusted gravity acceleration from accelerometer captured at a constant rate of 50 Hz in X dimension. Raw measurements were filtered using a median filter and a 3rd order low pass Butterworth filter with a corner frequency of 20 Hz to remove noise, then separated using another low pass Butterworth filter with a corner frequency of 0.3 Hz.
Mean of time domain means of adjusted gravity acceleration from accelerometer captured at a constant rate of 50 Hz in Y dimension. Raw measurements were filtered using a median filter and a 3rd order low pass Butterworth filter with a corner frequency of 20 Hz to remove noise, then separated using another low pass Butterworth filter with a corner frequency of 0.3 Hz.
Mean of time domain means of adjusted gravity acceleration from accelerometer captured at a constant rate of 50 Hz in Z dimension. Raw measurements were filtered using a median filter and a 3rd order low pass Butterworth filter with a corner frequency of 20 Hz to remove noise, then separated using another low pass Butterworth filter with a corner frequency of 0.3 Hz.
Mean of time domain means of adjusted gravity acceleration from accelerometer captured at a constant rate of 50 Hz in X dimension. Raw measurements were filtered using a median filter and a 3rd order low pass Butterworth filter with a corner frequency of 20 Hz to remove noise, then separated using another low pass Butterworth filter with a corner frequency of 0.3 Hz.
Mean of time domain standard deviations of adjusted gravity acceleration from accelerometer captured at a constant rate of 50 Hz in Y dimension. Raw measurements were filtered using a median filter and a 3rd order low pass Butterworth filter with a corner frequency of 20 Hz to remove noise, then separated using another low pass Butterworth filter with a corner frequency of 0.3 Hz.
Mean of time domain standard deviations of adjusted gravity acceleration from accelerometer captured at a constant rate of 50 Hz in Z dimension. Raw measurements were filtered using a median filter and a 3rd order low pass Butterworth filter with a corner frequency of 20 Hz to remove noise, then separated using another low pass Butterworth filter with a corner frequency of 0.3 Hz.
Gyroscope measurements.
Mean of time domain means of adjusted body axial measurements from gyroscope captured at a constant rate of 50 Hz in X dimension. Raw measurements were filtered using a median filter and a 3rd order low pass Butterworth filter with a corner frequency of 20 Hz to remove noise.
Mean of time domain means of adjusted body axial measurements from gyroscope captured at a constant rate of 50 Hz in Y dimension. Raw measurements were filtered using a median filter and a 3rd order low pass Butterworth filter with a corner frequency of 20 Hz to remove noise.
Mean of time domain means of adjusted body axial measurements from gyroscope captured at a constant rate of 50 Hz in Z dimension. Raw measurements were filtered using a median filter and a 3rd order low pass Butterworth filter with a corner frequency of 20 Hz to remove noise.
Mean of time domain standard deviations of adjusted body axial measurements from gyroscope captured at a constant rate of 50 Hz in X dimension. Raw measurements were filtered using a median filter and a 3rd order low pass Butterworth filter with a corner frequency of 20 Hz to remove noise.
Mean of time domain standard deviations of adjusted body axial measurements from gyroscope captured at a constant rate of 50 Hz in Y dimension. Raw measurements were filtered using a median filter and a 3rd order low pass Butterworth filter with a corner frequency of 20 Hz to remove noise.
Mean of time domain standard deviations of adjusted body axial measurements from gyroscope captured at a constant rate of 50 Hz in Z dimension. Raw measurements were filtered using a median filter and a 3rd order low pass Butterworth filter with a corner frequency of 20 Hz to remove noise.
The body linear acceleration and angular velocity were derived in time to obtain Jerk signals (tBodyAccJerk-XYZ and tBodyGyroJerk-XYZ).
Mean of the means of the Jerk acceleration as described above in X dimension.
Mean of the means of the Jerk acceleration as described above in Y dimension.
Mean of the means of the Jerk acceleration as described above in Z dimension.
Mean of the standard deviations of the Jerk acceleration as described above in X dimension.
Mean of the standard deviations of the Jerk acceleration as described above in Y dimension.
Mean of the standard deviations of the Jerk acceleration as described above in Z dimension.
Mean of the means of the gyrosocpe Jerk as described above in X dimension.
Mean of the means of the gyrosocpe Jerk as described above in Y dimension.
Mean of the means of the gyrosocpe Jerk as described above in Z dimension.
Mean of the standard deviations of the gyrosocpe Jerk as described above in X dimension.
Mean of the standard deviations of the gyrosocpe Jerk as described above in Y dimension.
Mean of the standard deviations of the gyrosocpe Jerk as described above in Z dimension.
Also the magnitude of these three-dimensional signals were calculated using the Euclidean norm (tBodyAccMag, tGravityAccMag, tBodyAccJerkMag, tBodyGyroMag, tBodyGyroJerkMag).
Mean of the means of the magnitude of three dimensional body accleration as described above.
Mean of the standrd deviation of the magnitude of three dimensional body accleration as described above.
Mean of the means of the magnitude of three dimensional gravity accleration as described above.
Mean of the standrd deviation of the magnitude of three dimensional gravity accleration as described above.
Mean of the means of the magnitude of three dimensional body accleration jerk as described above.
Mean of the standrd deviation of the magnitude of three dimensional body accleration jerk as described above.
Mean of the means of the magnitude of three dimensional body gyroscope signal as described above.
Mean of the standrd deviation of the magnitude of three dimensional body gyroscope signal as described above.
Mean of the means of the magnitude of three dimensional body gyroscope jerk as described above.
Mean of the standrd deviation of the magnitude of three dimensional body gyroscope jerk as described above.
Finally a Fast Fourier Transform (FFT) was applied to some of these signals producing fBodyAcc-XYZ, fBodyAccJerk-XYZ, fBodyGyro-XYZ, fBodyAccJerkMag, fBodyGyroMag, fBodyGyroJerkMag. (Note the 'f' to indicate frequency domain signals).
Mean of frequency domain (FFT) transformation applied to means of accellerometer raw signals in X dimension.
Mean of frequency domain (FFT) transformation applied to means of accellerometer raw signals in Y dimension.
Mean of frequency domain (FFT) transformation applied to means of accellerometer raw signals in Z dimension.
Mean of frequency domain (FFT) transformation applied to standard deviation of accellerometer raw signals in X dimension.
Mean of frequency domain (FFT) transformation applied to standard deviation of accellerometer raw signals in Y dimension.
Mean of frequency domain (FFT) transformation applied to standard deviation of accellerometer raw signals in Z dimension.
Mean of frequency domain (FFT) transformation applied to mean frequency of accellerometer raw signals in X dimension.
Mean of frequency domain (FFT) transformation applied to mean frequency of accellerometer raw signals in Y dimension.
Mean of frequency domain (FFT) transformation applied to mean frequency of accellerometer raw signals in Z dimension.
Frequency domain (FFT) of the body linear acceleration and angular velocity were derived in time to obtain Jerk signals (tBodyAccJerk-XYZ and tBodyGyroJerk-XYZ).
Mean of means of frequency domain (FFT) transformation applied to body acceleration jerk in X dimension.
Mean of means of frequency domain (FFT) transformation applied to body acceleration jerk in Y dimension.
Mean of means of frequency domain (FFT) transformation applied to body acceleration jerk in Z dimension.
Mean of standard deviations of frequency domain (FFT) transformation applied to body acceleration jerk in X dimension.
Mean of of standard deviations of frequency domain (FFT) transformation applied to body acceleration jerk in Y dimension.
Mean of of standard deviations of frequency domain (FFT) transformation applied to body acceleration jerk in Z dimension.
Mean of mean frequencies of frequency domain (FFT) transformation applied to body acceleration jerk in X dimension.
Mean of mean frequencies of frequency domain (FFT) transformation applied to body acceleration jerk in Y dimension.
Mean of mean frequencies of frequency domain (FFT) transformation applied to body acceleration jerk in Z dimension.
Mean of the means of frequency domain (FFT Transformation) of the body gyroscope signal in the X dimension.
Mean of the means of frequency domain (FFT Transformation) of the body gyroscope signal in the Y dimension.
Mean of the means of frequency domain (FFT Transformation) of the body gyroscope signal in the Z dimension.
Mean of the standard deviations of frequency domain (FFT Transformation) of the body gyroscope signal in the X dimension.
Mean of the standard deviations of frequency domain (FFT Transformation) of the body gyroscope signal in the Y dimension.
Mean of the standard deviations of frequency domain (FFT Transformation) of the body gyroscope signal in the Z dimension.
Mean of the mean frequencies of frequency domain (FFT Transformation) of the body gyroscope signal in the X dimension.
Mean of the mean frequencies of frequency domain (FFT Transformation) of the body gyroscope signal in the Y dimension.
Mean of the mean frequencies of frequency domain (FFT Transformation) of the body gyroscope signal in the Z dimension.
Mean of the means of frequency domain (FFT Transformation) of the magnitude of three dimensional body acceleration as described above.
Mean of the standard deviations of frequency domain (FFT Transformation) of the magnitude of three dimensional body acceleration as described above.
Mean of the mean frequencies of frequency domain (FFT Transformation) of the magnitude of three dimensional body acceleration as described above.
Mean of the means of frequency domain (FFT Transformation) of the magnitude of three dimensional body acceleration jerk as described above.
Mean of the standard deviations of frequency domain (FFT Transformation) of the magnitude of three dimensional body acceleration jerk as described above.
Mean of the mean frequencies of frequency domain (FFT Transformation) of the magnitude of three dimensional body acceleration jerk as described above.
Mean of the means of frequency domain (FFT Transformation) of the magnitude of three dimensional body gyroscope signal as described above.
Mean of the standard deviations of frequency domain (FFT Transformation) of the magnitude of three dimensional body gyroscope signal as described above.
Mean of the mean frequencies s of frequency domain (FFT Transformation) of the magnitude of three dimensional body gyroscope signal as described above.
Mean of the means of frequency domain (FFT Transformation) of the magnitude of three dimensional body gyroscope jerk as described above.
Mean of the standrd deviation of frequency domain (FFT Transformation) of the magnitude of three dimensional body gyroscope jerk as described above.
Mean of the mean frequency of frequency domain (FFT Transformation) of the magnitude of three dimensional body gyroscope jerk as described above.