4.6 Virtual Point quality

Within the Quality card, information is shown about the VP conditioning and contributions. These can be used in the preparation phase of a project to design a measurement setup that provides a sufficient base for the VP calculations to come.

In the following video, the quality indicators of the Prepare module of DIRAC are explained.

Virtual Point conditioning matrix

Two conditioning matrices are shown on the left side of the Quality card and show how well the DoFs of each VP are conditioned, for respectively the VP response channels (left) and VP force channels (right). It is used as follows:

• Darker colors represent better conditioning. Values of 100% are the theoretically best possible conditioning but are rare. Grey values appear if that particular VP DoF has been deactivated. White values indicate a deficiency in the Virtual Point: it shows that that VP is underdetermined. In that case, either add more measurement channels or deactivate some VP DoF.
• When additional sensors and impacts are mapped to a VP, the refresh button must be pressed to update the conditioning matrix.

Virtual Point contribution matrix

Two contribution matrices are shown on the right side of the quality card and show the contribution of every measurement DoF. Here, the response (sensor) channels are shown on top and the force (excitation) channels below. The contribution matrices apply to the currently selected VP, as chosen in the drop-down box in the top right corner.  It is used as follows:

• The matrix shows how much each sensor channel/excitation is contributing to the VP. The vertical sum of all columns becomes 100%, so a value of, for instance, 25% in the TY column means that the VP Y-translation is determined for 25% from that channel and 75% from other channels.
• The darker colors show high contributions. Hover over a box to review the contribution in percent.

If one channel/excitation dominates the contribution, that box will turn reddish, and additional sensors/impacts should be defined to capture that VP DoF.