Systems, located under the Structures ribbon, can be used as reference frames when using Angle or Length measures in a motion analysis.
In the context of a motion analysis, these measures are referred to as “Persistent Measures”, because they continually update during the motion simulation.
By default, when a measure is created, it uses the Global reference frame as its reference. Global orientation is the same as model “Orientation Indicator” located at the bottom-left corner of the model window. However, any user-defined System can be assigned as a reference to the measure, rather than Global only. Simply change the “System” of the measure to be whichever is preferred.
Measures can be plotted to show quantities like displacement, relative velocity, and acceleration. The results are shown relative to the “System” used for the measure.
By default, the measure visually displays the magnitude (line of sight distance). If you double-click the measure graphic on the screen, it will expand to show x, y and z components as well.
This video shows how to create a System and assigning to a Measure: