SDFusion is an add-on for Fusion 360 that can automatically generate an SDF description of the model as well as export meshes or additional markers. Examples can be found here.
- Clone or download the SDFusion repository
git clone https://github.com/Roboy/SDFusion.git - Open
Scripts and Add-Insdialog in Fusion 360 by pressingShift+S - Click on the
Add-Instab and press the green plus icon on the top - Navigate to the SDFusion folder and select it.
You should be able to run/debug the add-in from the
Scripts and Add-Insdialog now:
- Switch Fusion360 design configuration to Z-axis up (default is Y up).
- Break all links in the design at all hierarchy levels.
- Create rigid groups for all links of the robot and call them
EXPORT_link_name. For example, select all components that belong tobaselink, create a rigid group calledEXPORT_base. - Define all joints between the links and call them
EXPORT_joint_name. Select child asComponent1and parent asComponent2. Child and parent component must belong to two different rigid groups, e.g. links. Supported joint types are: fixed, revolute, prismatic and ball. Other joints that are defined in the design, but are not used for export are known to cause issues, so it's recommended to remove from the design all other joints withoutEXPORT_in their name. - Define joint limits for the joints. Otherwise, min and max joint limit will be exported as 0.
Now the model is ready to be exported.
SDFusion requires all the links to be defined as rigid groups in Fusion 360. The script will automatically:
- create and export an STL mesh of the link
- calculate intertia and center of mass
- generate a
model.sdffile with all rigid groups as links
Rigid group names have to follow the naming convetion: EXPORT_link_name. The rigid group has to contain all components (including children) that consitute the link.
In order to export a joint, it has to be
- defined between components that belong to different rigid groups
- called
EXPORT_joint_name
When creating a joint in Fusion 360, make sure you select the child first and then the parent. Currently, fixed, prismatic, revolute joint types are supported. A ball-and-socket joint can be emulated as a gimbal joint - a series of three 1-DoF revolute joints nested in each other.
SDFusion allows to export cable-driven robot models with multiple attachment points (via-points).
The naming scheme defined for the viapoints is the following: VP_motornumber_EXPORT_linkname_viapointnumber (e.g. VP_motor0_EXPORT_base_0). You can either add them manually as construction points in Fusion 360 or use ViaPoints tab from the plugin.
Here, you have to specify the motor number and the link name. Press Select and the viapont number will increment automatically as you click on circular edges in your design. The newly created attachement points are listed under the Construction in the Fusion 360 browser.
Refer to CARDSflow to learn about possible options to control your cable robot.
| Configuration | Explanation |
|---|---|
| updateRigidGroups | by default the script will cache your rigid groups, as each of them is copied to a new component. This is done to save time for the subsequent exports, since this step is time consuming. If you add or remove components from a rigid group, check this box to update it. |
| exportMeshes | creates a folder with stl meshes for each rigid group |
| sdf | model.sdf is created |
| viapoints | model.sdf will include descriptions of viapoints |
| caspr | only valid when viapoints are defined and checked; generates CASPR files with definitions of bodies and cables, that are required for controlling the robot |
| opensim | generates a separate muscles.osim file with muscle descriptions in OpenSim format |
| darkroom | exports visual markers defined on the robot |
| remove parts smaller 1g | deletes all components in the design with mass less than 1g |
| self_collide | <self_collide>false</self_collide> tag in model.sdf |
| dummy_inertia | ignores real inertia values calculated from your design |