Control Rig Animation Blueprint Node

Once you have created a Control Rig Blueprint, you can use the Control Rig node inside the AnimGraph of an Animation Blueprint to augment animation data with the content you provide in your Control Rig Blueprint. This enables you accomplish tasks like blending animation data with the contents of a Control Rig Blueprint or layer the content of a Control Rig Blueprint on top of an existing animation data.

The example below illustrates how you can use a Control Rig Blueprint to instruct one Joint to aim at and follow another Joint. With the Control Rig created, you can then use the Control Rig node and incorporate the Control Rig contents into an existing Animation Blueprint that is playing an animation.

Steps

For this example, we are using a new Blueprint Third Person Template project. 

1. In your project after enabling the Control Rig Plugin, click the Add New button and under Animation, select Control Rig. 
   

2. Select the ControlRig as the Parent Rig, then click Create and give it any name.  
   

3. Inside the Control Rig Blueprint, right-click in the Hierarchy tab and under Import, assign the SK_Mannequin. 
   

4. In the Preview Scene Settings tab, assign the SK_Mannequin as the Preview Mesh. 
   

5. Compile the Control Rig Blueprint. 
   

6. Right-click in the graph and create a Rig Hierarchy Ref variable. 
   

7. In the Details panel for the Rig Hierarchy Ref, change the Variable Name to Base_Hierarchy. 
   
   This creates a reference to the hierarchy and is usually a good practice to rename it to something more relatable like Base Hierarchy.

8. Off the out pin, use the Get Joint Transform node with Joint set to hand_r and Type set to Current.
   
   This will be the target Joint to aim at and we will get the current transform value of that Joint.

9. Right-click in the graph and add an Aim Constraint node.
   

10. Compile the Blueprint.

11. Connect the Base_Hierarchy and Get Joint Transform nodes to the Aim Constraint as shown below with the following settings:
    Joint = head
    Aim Vector Y = 1.0
    Aim Target Weight = 1.0
    Here we are instructing the head Joint to aim along the Y axis at the transform of the right hand.

12. In the Content Browser under Content > Mannequin > Character > Mesh, right-click on the UE4_Mannequin_Skeleton and select Create > Anim Blueprint and give it any name.
    

13. On the AnimGraph inside the Animation Blueprint, connect a Control Rig node (with your Control Rig Class assigned) to the Final Animation Pose.
    

14. Add and connect the ThirdPersonIdle animation to Control Rig and compile.
    
    The character will start to idle while looking towards their right hand. As the right hand moves, the character will automatically move its head to aim at (looking at) the right hand. You can further test this by adding a Transform Modify Bone node to the graph so you can manipulate it inside the Viewport.

15. Add a Transform Modify Bone node between the Control Rig and Play ThirdPersonIdle animation (conversion nodes will automatically be created).
    

16. In the Details panel for Transform Modify Bone, set the Bone to Modify to upperarm_r and Rotation Mode to Add to Existing.
    

17. Compile the Animation Blueprint.

End Result

You can now rotate the right arm inside the Viewport and the head will follow the location of the hand. You can also change out different animations or adjust the Rotation Space to achieve different results.