Object wont return to localposition of moving parent?

So I have an object "Centerax" which moves on its local X-axis, however I need it to be always trying to return to its original position relative to its parent object.

Currently my code below is giving me the errors listed and nothing I've tried seems to fix it.

 public Transform target;
 public float upDistance    = 7.0f;
 public float backDistance  = 10.0f;
 public float trackingSpeed = 3.0f;
 public float rotationSpeed = 9.0f;
 public float returnSpeed = 3.0f;

 public HoverControl hcs;

 private Vector3 vPos;
 private Vector3 oPos;
 private Quaternion rPos;

 void Start ()
 {
     oPos = target.localPosition;
 }

 void FixedUpdate () 
 {
     float mvSlide = -Input.GetAxis("Horizontal") * (hcs.agility * 2);

     vPos = target.position - target.forward * backDistance + target.up * upDistance;
     transform.position = Vector3.Lerp (transform.position, vPos, trackingSpeed * Time.deltaTime * hcs.velocity);

     rPos = Quaternion.LookRotation(target.position - transform.position, target.up);
     transform.rotation = Quaternion.Slerp (transform.rotation, rPos, rotationSpeed * Time.deltaTime * (hcs.agility * 2));


     hcs.centerax.transform.Translate(new Vector3(Mathf.Lerp(-mvSlide, mvSlide, Time.smoothDeltaTime), 0, 0));


     Vector3 tmpPos = hcs.centerax.transform.localPosition;
     tmpPos.x = Mathf.Clamp (tmpPos.x, -1f, 1f);
     hcs.centerax.transform.localPosition = tmpPos;


     hcs.centerax.transform.localPosition = Vector3.Lerp (hcs.centerax.transform.localPosition.x, oPos, Time.deltaTime * returnSpeed);
 }

}

Errors:

The best overloaded method match for `UnityEngine.Vector3.Lerp(UnityEngine.Vector3, UnityEngine.Vector3, float)' has some invalid arguments

Cannot convert 'Float' expression to type 'UnityEngine.Vector3'