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# Tips

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# Tips

When you are working with the 2D-Library for small angles, it is good to keep the following tips in mind:

 • The 2DSmallRotations library is very well suited for frequency domain analysis through linearization.
 • The 2DSmallRotations library is not suited for large rotations. Consider a rotation of 0.05 degrees or 1 mrad as an upper bound for every model part.
 • It is not possible in 20-sim to use vector elements with mixed units. Therefore element number 3 will be displayed with units [m/s] and [N] although it really is [rad/s] and [Nm]!
 • The vector element number (1, 2 or 3) denotes the degree of freedom. Flipping or rotating of a model does not change this degree (e.g. a rotation does not change from x into y). Preferably leave the orientation of the models as they pop up on the screen.
 • To create intuitive models, the positive direction of each degree of freedom is defined as: x from left to right, y from bottom to top, ? counter clockwise.
 • To prevent misinterpretation of a model by other users, stick to the drawing rules that are given.
 • A TwoDBody model can be connected to any other element of the 2D-library except other 2D-bodies.
 • A TwoDBody model can be connected to 1D models using the TwoDPoint models as intermediate.
 • TwoDPoint models can only be connected to TwoDBody models.
 • If a TwoDBody model is connected to TwoDPoint models only, it has to be connected to at least three non-coinciding, unequal (i.e. not having the same offsets) TwoDPoints to prevent it from free motion.