Smooth Grid Movement

I try the grid system from the wiki link text

but with a 3rd person camera i notice that a hiccup on the contentious movement.

i try iTween for smooth movement but every method i tried to reposition the player on round number. nothing worked out.

one example of my tests. in this i use the same method a Coroutine and a boolean. but that's why i get the same result;

     using UnityEngine;
     using System.Collections;
     
     public class MoveForwardTest : MonoBehaviour {
         
         public int speed = 4;
         public bool isIdle = true;
         
         // Use this for initialization
         void Start () {
         
         }
         
         // Update is called once per frame
         void LateUpdate () {
             if(Input.GetAxisRaw("Vertical") == 1 && isIdle) {
                 StartCoroutine("MoveForward");
             }
             
             
         }
         public IEnumerator MoveForward()
         {
             isIdle = false;
             //iTween.MoveAdd( gameObject, iTween.Hash("z",1,"oncomplete","IsIdle"));
             yield return 0;
         }
         
         void IsIdle()
         {
             isIdle = true;    
         }
     }
 }