.Modelica.Mechanics.MultiBody.Joints.SphericalSpherical .Modelica.Mechanics.MultiBody.Joints.SphericalSphericalJoint that has a spherical joint on each of its two ends. The rod connecting the two spherical joints is approximated by a point mass that is located in the middle of the rod. When the mass is set to zero (default), special code for a massless body is generated. In the following default animation figure, the two spherical joints are represented by two red spheres, the connecting rod by a grey cylinder and the point mass in the middle of the rod by a light blue sphere:
This joint introduces one constraint defining that the distance between the origin of frame_a and the origin of frame_b is constant (= rodLength). It is highly recommended to use this joint in loops whenever possible, because this enhances the efficiency considerably due to smaller systems of non-linear algebraic equations.
It is sometimes desirable to compute the rodLength of the connecting rod during initialization. For this, parameter computeLength has to be set to true and instead one other, easier to determine, position variable in the same loop needs to have a fixed attribute of true. For example, if a loop consists of one Revolute joint, one Prismatic joint and a SphericalSpherical joint, one may fix the start values of the revolute joint angle and of the relative distance of the prismatic joint in order to compute the rodLength of the rod.
It is not possible to connect other components, such as a body with mass properties or a special visual shape object to the rod connecting the two spherical joints. If this is needed, use instead joint Joints.UniversalSpherical that has this property.