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.
Subsequently, the body linear acceleration and angular velocity were derived in time to obtain Jerk signals (tBodyAccJerk-XYZ and tBodyGyroJerk-XYZ). Also the magnitude of these three-dimensional signals were calculated using the Euclidean norm (tBodyAccMag, tGravityAccMag, tBodyAccJerkMag, tBodyGyroMag, tBodyGyroJerkMag).
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).
These signals were used to estimate variables of the feature vector for each pattern:
'-XYZ' is used to denote 3-axial signals in the X, Y and Z directions.
After performing the following actions on the original data set (as explained above), following are the features present in the file aggdata.txt. All the features except "activity" and "subject" are the mean (average) values of the original measures recorded for each activity per subject. Only mean and standard deviation features were selected from the original dataset and included in this data set.
"activity" : Activity label with possible values: WALKING, WALKING_UPSTAIRS, WALKING_DOWNSTAIRS, SITTING, STANDING, LAYING
"subject" : Each row identifies the subject who performed the activity. Its range is from 1 to 30.
"timeBodyAccelerationMean-X"
"timeBodyAccelerationMean-Y"
"timeBodyAccelerationMean-Z"
"timeGravityAccelerationMean-X"
"timeGravityAccelerationMean-Y"
"timeGravityAccelerationMean-Z"
"timeBodyAccelerationJerkMean-X"
"timeBodyAccelerationJerkMean-Y"
"timeBodyAccelerationJerkMean-Z"
"timeBodyGyroscopeMean-X"
"timeBodyGyroscopeMean-Y"
"timeBodyGyroscopeMean-Z"
"timeBodyGyroscopeJerkMean-X"
"timeBodyGyroscopeJerkMean-Y"
"timeBodyGyroscopeJerkMean-Z"
"timeBodyAccelerationMagnitudeMean"
"timeGravityAccelerationMagnitudeMean"
"timeBodyAccelerationJerkMagnitudeMean"
"timeBodyGyroscopeMagnitudeMean"
"timeBodyGyroscopeJerkMagnitudeMean"
"frequencyBodyAccelerationMean-X"
"frequencyBodyAccelerationMean-Y"
"frequencyBodyAccelerationMean-Z"
"frequencyBodyAccelerationMeanFrequency-X"
"frequencyBodyAccelerationMeanFrequency-Y"
"frequencyBodyAccelerationMeanFrequency-Z"
"frequencyBodyAccelerationJerkMean-X"
"frequencyBodyAccelerationJerkMean-Y"
"frequencyBodyAccelerationJerkMean-Z"
"frequencyBodyAccelerationJerkMeanFrequency-X"
"frequencyBodyAccelerationJerkMeanFrequency-Y"
"frequencyBodyAccelerationJerkMeanFrequency-Z"
"frequencyBodyGyroscopeMean-X"
"frequencyBodyGyroscopeMean-Y"
"frequencyBodyGyroscopeMean-Z"
"frequencyBodyGyroscopeMeanFrequency-X"
"frequencyBodyGyroscopeMeanFrequency-Y"
"frequencyBodyGyroscopeMeanFrequency-Z"
"frequencyBodyAccelerationMagnitudeMean"
"frequencyBodyAccelerationMagnitudeMeanFrequency"
"frequencyBodyAccelerationJerkMagnitudeMean"
"frequencyBodyAccelerationJerkMagnitudeMeanFrequency"
"frequencyBodyGyroscopeMagnitudeMean"
"frequencyBodyGyroscopeMagnitudeMeanFrequency"
"frequencyBodyGyroscopeJerkMagnitudeMean"
"frequencyBodyGyroscopeJerkMagnitudeMeanFrequency"
"angle(tBodyAccelerationMean,gravity)"
"angle(tBodyAccelerationJerkMean),gravityMean)"
"angle(tBodyGyroscopeMean,gravityMean)"
"angle(tBodyGyroscopeJerkMean,gravityMean)"
"angle(X,gravityMean)"
"angle(Y,gravityMean)"
"angle(Z,gravityMean)"
"timeBodyAccelerationSTD-X"
"timeBodyAccelerationSTD-Y"
"timeBodyAccelerationSTD-Z"
"timeGravityAccelerationSTD-X"
"timeGravityAccelerationSTD-Y"
"timeGravityAccelerationSTD-Z"
"timeBodyAccelerationJerkSTD-X"
"timeBodyAccelerationJerkSTD-Y"
"timeBodyAccelerationJerkSTD-Z"
"timeBodyGyroscopeSTD-X"
"timeBodyGyroscopeSTD-Y"
"timeBodyGyroscopeSTD-Z"
"timeBodyGyroscopeJerkSTD-X"
"timeBodyGyroscopeJerkSTD-Y"
"timeBodyGyroscopeJerkSTD-Z"
"timeBodyAccelerationMagnitudeSTD"
"timeGravityAccelerationMagnitudeSTD"
"timeBodyAccelerationJerkMagnitudeSTD"
"timeBodyGyroscopeMagnitudeSTD"
"timeBodyGyroscopeJerkMagnitudeSTD"
"frequencyBodyAccelerationSTD-X"
"frequencyBodyAccelerationSTD-Y"
"frequencyBodyAccelerationSTD-Z"
"frequencyBodyAccelerationJerkSTD-X"
"frequencyBodyAccelerationJerkSTD-Y"
"frequencyBodyAccelerationJerkSTD-Z"
"frequencyBodyGyroscopeSTD-X"
"frequencyBodyGyroscopeSTD-Y"
"frequencyBodyGyroscopeSTD-Z"
"frequencyBodyAccelerationMagnitudeSTD"
"frequencyBodyAccelerationJerkMagnitudeSTD"
"frequencyBodyGyroscopeMagnitudeSTD"
"frequencyBodyGyroscopeJerkMagnitudeSTD"