Table of Contents
Multiply_Signals_By_Constant
The Multiply Signals By Constant command can be used to multiply signals by a constant value. This can be useful in cases where a signal is consistently incorrect by a known factor.
Pipeline Command
The Multiply Signals By Constant command can be found in the pipeline workshop within the Signal Math folder as so:
Multiply_Signals_By_Constant ! /SIGNAL_TYPES= ! /SIGNAL_FOLDER=ORIGINAL ! /SIGNAL_NAMES= ! /SIGNAL_COMPONENTS= ! /RESULT_TYPES= ! /RESULT_FOLDERS=PROCESSED ! /RESULT_NAME= ! /APPLY_AS_SUFFIX_TO_SIGNAL_NAME= ! /CONSTANT=0 ;
Command Parameters
The parameters that can be used to control the command are as follows:
| Signal Types | The type of signal to multiply the constant by |
| Signal Folder | The name of the signal folder |
| Signal Names | The name of each signal to be included |
| Signal Components | Which signal components to include in operation |
| Result Types | What type of signal will be produced |
| Result Folders | The name of the resulting folder |
| Result Name | The name of the resulting signal |
| Apply As Suffix To Signal Name | Apply a suffix to the original signal name |
| Constant | The value by which the original signal(s) will be multiplied |
Dialog
The command can be edited as text or using the dialog box:
Example: Multiplying to Account for Known Error
In this hypothetical scenario, force plate data is being recorded by 2 force plates that are known to consistently under report data by 25% percent. In order to correct for this we can use the multiply signals by constant command like so:
Multiply_Signals_By_Constant /SIGNAL_TYPES=FORCE ! /SIGNAL_FOLDER=ORIGINAL /SIGNAL_NAMES=FP1+FP2 /SIGNAL_COMPONENTS=X+Y+Z /RESULT_TYPES=DERIVED ! /RESULT_FOLDERS=PROCESSED /RESULT_NAME=Corrected_Force1+Corrected_Force2 ! /APPLY_AS_SUFFIX_TO_SIGNAL_NAME= /CONSTANT=1.25 ;
Example: Negate Signals
In some cases, like for internal/external rotation of the hip, the signal for the left or right joint must be negated in order to properly compare the magnitude of the angles at the same point in time. This example shows how multiplying the Z component of the right hip angle by -1 can be used to flip the signal for easier comparison with the left side:
Multiply_Signals_By_Constant /SIGNAL_TYPES=LINK_MODEL_BASED ! /SIGNAL_FOLDER=ORIGINAL /SIGNAL_NAMES=RHipAngle /SIGNAL_COMPONENTS=Z /RESULT_TYPES=LINK_MODEL_BASED ! /RESULT_FOLDERS=PROCESSED /RESULT_NAME=RHi[_Negated ! /APPLY_AS_SUFFIX_TO_SIGNAL_NAME= /CONSTANT=-1 ;
The resulting flipped angle signal looks like so:
