Physics based recoil - Quiaternion problems

Scripting
1

I am working implementing a recoil model for a FPS gun.

I have looked at
http://forum.unity3d.com/viewtopic.php?t=20059&highlight=recoil

-But not found this approach to work. I cant seem to configure the ConfigurableJoint so ithas the tension I want.

Therefore I have started implementing a small script that manipulates the localPosition and localRotation parts of the right hand of my character.

I use the verlet method to update the position, and this works fine for translation.

BUT!!!

My approach breaks down when I try to do the same with the quaternion based rotations.

Any suggestions on how to do the same with quaternions?

using UnityEngine;
using System.Collections;

public class Sway : MonoBehaviour {
	
	private Vector3 pOrig;
	private Vector3 pNow;
	private Vector3 pLast;
	
	private float inversemass= 0.001f;
	private float LinearStiffness = 1000000.0f;
	private float LinearDamping = 0.35f;
	
	void Awake()
	{
		print("Awake...");	
		pOrig = transform.localPosition;
		pLast = new Vector3(0,0,0);
	}

	void LateUpdate ()
	{
		Vector3 LinearAcceleration;
		Vector3 tmpV;
		LinearAcceleration =  pNow*(LinearStiffness*inversemass);
		tmpV = pNow;
		pNow = (2.0f - LinearDamping)*pNow-(1.0f-LinearDamping)*pLast - LinearAcceleration * Time.deltaTime * Time.deltaTime;
		pLast = tmpV;
		transform.localPosition = pOrig + pNow;
	}
	void kick()
	{
		print("Kick");
		pLast = transform.localRotation * new Vector3(0.02f,0.0f,0.0f);
	}
	
	void Update()
	{
		if(Input.GetKeyDown("k"))
		{
			kick();
		}
	}
}
2

Just tested this on an object in my project. My objects have crazy locals from the 3D models, so adjust the euler kick accordingly

using UnityEngine;
using System.Collections;

public class Sway : MonoBehaviour {
   
   private Vector3 pOrig;
   private Vector3 pNow;
   private Vector3 pLast;
   
   private float inversemass= 0.001f;
   private float LinearStiffness = 1000000.0f;
   private float LinearDamping = 0.35f;
   
   private Quaternion origRot;
   
   void Awake()
   {
      print("Awake...");   
      pOrig = transform.localPosition;
      origRot = transform.localRotation;
      pLast = new Vector3(0,0,0);
   }

   void LateUpdate ()
   {
      Vector3 LinearAcceleration;
      Vector3 tmpV;
      LinearAcceleration =  pNow*(LinearStiffness*inversemass);
      tmpV = pNow;
      pNow = (2.0f - LinearDamping)*pNow-(1.0f-LinearDamping)*pLast - LinearAcceleration * Time.deltaTime * Time.deltaTime;
      pLast = tmpV;
      transform.localPosition = pOrig + pNow;
      transform.localRotation = Quaternion.Lerp(transform.localRotation, origRot, Time.deltaTime * 20);
   }
   void kick()
   {
      print("Kick");
      pLast = transform.localRotation * new Vector3(0.02f,0.0f,0.0f);
      transform.localRotation *= Quaternion.Euler(0, 10, 0);
   }
   
   void Update()
   {
      if(Input.GetKeyDown("k"))
      {
         kick();
      }
   }
}