JointSSR
Spherical - spherical - revolute joint aggregation with mass (no constraints, no potential states)
Library
Modelica/Mechanics/MultiBody/Joints/Assemblies
Description
This component consists of a spherical joint 1 at frame_a, a revolute joint at frame_b and a spherical joint 2 which is connected via rod 1 to the spherical joint 1 and via rod 2 to the revolute joint, see the default animation in the following figure (the axes vectors are not part of the default animation):
Besides an optional point mass in the middle of rod 1, this joint aggregation has no mass and no inertia, and introduces neither constraints nor potential state variables. It should be used in kinematic loops whenever possible since the non-linear system of equations introduced by this joint aggregation is solved analytically (i.e., a solution is always computed, if a unique solution exists).
An additional frame_ib is present. It is fixed in rod 2 connecting the revolute and the spherical joint at the side of the revolute joint that is connected to this rod (= rod2.frame_a = revolute.frame_a).
An additional frame_im is present. It is fixed in rod 2 connecting the revolute and the spherical joint at the side of spherical joint 2 that is connected to this rod (= rod2.frame_b). It is always parallel to frame_ib.
The easiest way to define the parameters of this joint is by moving the MultiBody system in a reference configuration where all frames of all components are parallel to each other (alternatively, at least frame_b and frame_ib of the JointSSR joint should be parallel to each other when defining an instance of this component).
Parameters
| Name | Label | Description | Data Type | Valid Values |
|---|---|---|---|---|
mo_animation | animation | = true, if animation shall be enabled | Scalar | true |
mo_showMass | showMass | = true, if point mass on rod 1 shall be shown (provided animation = true and rod1Mass > 0) | Scalar | true |
mo_rod1Length | rod1Length | Distance between the origins of the two spherical joints | Scalar | |
mo_rod1Mass | rod1Mass | Mass of rod 1 (= point mass located in middle of rod connecting the two spherical joints) | Scalar | |
mo_n_b | n_b | Axis of revolute joint fixed and resolved in frame_b | Vector of size 3 | |
mo_rRod2_ib | rRod2_ib | Vector from origin of frame_ib to spherical joint in the middle, resolved in frame_ib | Vector of size 3 | |
mo_phi_offset | phi_offset | Relative angle offset of revolute joint (angle = phi(t) + from_deg(phi_offset)) | Scalar | |
mo_phi_guess | phi_guess | Select the configuration such that at initial time |phi(t0) - from_deg(phi_guess)| is minimal | Scalar |
| Name | Label | Description | Data Type | Valid Values |
|---|---|---|---|---|
mo_sphereDiameter | sphereDiameter | Diameter of the spheres representing the two spherical joints | Scalar | |
mo_sphereColor | sphereColor | Color of the spheres representing the two spherical joints | Vector of size 3 | |
mo_rod1Diameter | rod1Diameter | Diameter of rod 1 connecting the two spherical joints | Scalar | |
mo_rod1Color | rod1Color | Color of rod 1 connecting the two spherical joint | Vector of size 3 | |
mo_rod2Diameter | rod2Diameter | Diameter of rod 2 connecting the revolute joint and spherical joint 2 | Scalar | |
mo_rod2Color | rod2Color | Color of rod 2 connecting the revolute joint and spherical joint 2 | Vector of size 3 | |
mo_revoluteDiameter | revoluteDiameter | Diameter of cylinder representing the revolute joint | Scalar | |
mo_revoluteLength | revoluteLength | Length of cylinder representing the revolute joint | Scalar | |
mo_revoluteColor | revoluteColor | Color of cylinder representing the revolute joint | Vector of size 3 | |
mo_specularCoefficient | specularCoefficient | Reflection of ambient light (= 0: light is completely absorbed) | Scalar |
| Name | Label | Description | Data Type | Valid Values |
|---|---|---|---|---|
mo_checkTotalPower | checkTotalPower | = true, if total power flowing into this component shall be determined (must be zero) | Scalar | true |
| Name | Label | Description | Data Type | Valid Values |
|---|---|---|---|---|
mo_aux | aux | aux | Structure | |
mo_aux/fixed | fixed | Cell of scalars | true | |
mo_aux/start | start | Cell of scalars | ||
mo_f_rod | f_rod | f_rod | Structure | |
mo_f_rod/fixed | fixed | Cell of scalars | true | |
mo_f_rod/start | start | Cell of scalars | ||
mo_totalPower | totalPower | totalPower | Structure | |
mo_totalPower/fixed | fixed | Cell of scalars | true | |
mo_totalPower/start | start | Cell of scalars |
Ports
| Name | Type | Description | IO Type | Number |
|---|---|---|---|---|
frame_a | implicit | Coordinate system fixed to the component with one cut-force and cut-torque | input | 1 |
frame_b | implicit | Coordinate system fixed to the component with one cut-force and cut-torque | output | 1 |
frame_ib | implicit | Coordinate system at origin of frame_b fixed at connecting rod of spherical and revolute joint | output | 2 |
frame_im | implicit | Coordinate system at origin of spherical joint in the middle fixed at connecting rod of spherical and revolute joint | output | 3 |
axis | implicit | 1-dim. rotational flange that drives the revolute joint | input | 2 |
bearing | implicit | 1-dim. rotational flange of the drive bearing of the revolute joint | output | 4 |