class SignConventions "Sign Conventions"
extends Modelica.Icons.Information;
annotation (
DocumentationClass = true,
Documentation(info = "<html>\n\n<p>\nThe variables of a component of this library can be accessed in the\nusual way. However, since most of these variables are basically elements\nof <strong>vectors</strong>, i.e., have a direction, the question arises how the\nsigns of variables shall be interpreted. The basic idea is explained\nat hand of the following figure:\n</p>\n\n<p>\n<img src=\"modelica://Modelica/Resources/Images/Mechanics/Translational/drive2.png\" alt=\"drive2\">\n</p>\n\n<p>\nFirst, one has to define\na <strong>positive</strong> direction of this line, called <strong>axis of movement</strong>.\nIn the top part of the figure this is characterized by an arrow\ndefined as <code>axis of movement</code>. The simple rule is now:\nIf a variable of a component is positive and can be interpreted as\nthe element of a vector (e.g., force or velocity vector), the\ncorresponding vector is directed into the positive direction\nof the axis of movement. In the following figure, the right-most\nmass of the figure above is displayed with the positive\nvector direction displayed according to this rule:\n</p>\n\n<p>\n<img src=\"modelica://Modelica/Resources/Images/Mechanics/Translational/drive3.png\" alt=\"drive3\">\n</p>\n<p>\nThe cut-force <code>m2.flange_a.f</code>\nof the right mass is directed into the\ndirection of movement if the values are positive. Similarly,\nthe velocity <code>m2.v</code> of the right mass\nis also directed into the\ndirection of movement if the values are positive\n</p>\n</html>"));
end SignConventions;