Rigidbody MoveRotation for childs

Hi.

In Unity FixedUpdate() function I call next code:

Code (CSharp):

1.  
2. public void Move(float x, float z)
3. {
4.        Vector3 targetPosition = new Vector3(x, transform.position.y, z);
5.  
6.         foreach (Transform child in transform)
7.         {
8.             if(child.rigidbody != null )
9.             {
10.                 Quaternion targetRotation = Quaternion.LookRotation(targetPosition - child.transform.position);
11.                 child.rigidbody.MoveRotation( Quaternion.Slerp(child.transform.rotation, targetRotation, Time.deltaTime * 10f)  ); // NOT WORK
12.             }
13.         }
14.  
15. rigidbody.MovePosition( Vector3.MoveTowards(transform.position, targetPosition, Time.deltaTime * moveSpeed) );
16. }
17.  

When I change child.rigidbody.MoveRotation to child.transform.rotation:

Code (CSharp):

1. child.transform.rotation =Quaternion.Slerp(child.transform.rotation, targetRotation,Time.deltaTime *10f);

everything works as I espect, but as I know its very bad practice to use "transform.rotation =" for rigidbody.

Parent and all its child has "IsKinematic = true";

Can you help me ? What`s wrong with child.rigidbody.MoveRotation ?

 

Do the child objects really need to have rigidbodies at all? Maybe you could describe what type of object you are simulating here - from the code it looks like you might be pointing wheels or guns or something but it isn't clear exactly what effect you want to create.