Google VR : Camera controller script confused

Hi,

I wrote a code to move the "Main Camera" using the up, down, right, left keys for the new update of Google VR SDK. I used the code Autowalk.cs that worked with the older version of Cardboard Unity Master, but today when I simply orients the camera without touching the keys, the camera starts moving by itself with no way to stop it.

So maybe I didn't write the code well. Do you have any where this problem comes from and how I could solve it ? Do you have any idea ?

Code (CSharp):

1. using UnityEngine;
2. using System.Collections;
3.  
4. public class walking_camera : MonoBehaviour
5. {
6.  
7.     // This variable determinates if the player will move or not
8.     private bool isWalkingup = false;
9.     private bool isWalkingdown = false;
10.     private bool isWalkingright = false;
11.     private bool isWalkingleft = false;
12.  
13.     Camera head = null;
14.  
15.     //La variable permettant de choisir la vitesse de deplacement
16.     [Tooltip("Renseigner la vitesse de deplacement de la camera")]
17.     public float speed;
18.  
19.     [Tooltip("Activer cette case pour bloquer l'axe y de la camera")]
20.     public bool freezeYPosition;
21.  
22.     [Tooltip("Renseigner l'axe y de la camera")]
23.     public float yOffset;
24.  
25.     void Start ()
26.     {
27.         head = Camera.main;
28.     }
29.  
30.     void Update ()
31.     {
32.         // FORWARD
33.  
34.         if (Input.GetKey("up"))
35.         {
36.             isWalkingup = true;
37.         }
38.         else if (!Input.GetKey("up"))
39.         {
40.             isWalkingup = false;
41.         }
42.  
43.         if (isWalkingup)
44.         {
45.             Vector3 direction = new Vector3(head.transform.forward.x, 0, head.transform.forward.z).normalized * speed * Time.deltaTime;
46.             Quaternion rotation = Quaternion.Euler(new Vector3(0, -transform.rotation.eulerAngles.y, 0));
47.             transform.Translate(rotation * direction);
48.         }
49.  
50.         // REARWARD
51.  
52.         if (Input.GetKey("down"))
53.         {
54.             isWalkingdown = true;
55.         }
56.         else if (!Input.GetKey("down"))
57.         {
58.             isWalkingdown = false;
59.         }
60.      
61.         if (isWalkingdown)
62.         {
63.             Vector3 direction = new Vector3(-head.transform.forward.x, 0, -head.transform.forward.z).normalized * speed * Time.deltaTime;
64.             Quaternion rotation = Quaternion.Euler(new Vector3(0, -transform.rotation.eulerAngles.y, 0));
65.             transform.Translate(rotation * direction);
66.         }
67.  
68.         // TO RIGHT
69.      
70.         if (Input.GetKey("right"))
71.         {
72.             isWalkingright = true;
73.         }
74.         else if (!Input.GetKey("right"))
75.         {
76.             isWalkingright = false;
77.         }
78.      
79.         if (isWalkingright)
80.         {
81.             Vector3 direction = new Vector3(head.transform.forward.z, 0, -head.transform.forward.x).normalized * speed * Time.deltaTime;
82.             Quaternion rotation = Quaternion.Euler(new Vector3(0, -transform.rotation.eulerAngles.y, 0));
83.             transform.Translate(rotation * direction);
84.         }
85.  
86.         // TO LEFT
87.      
88.         if (Input.GetKey("left"))
89.         {
90.             isWalkingleft = true;
91.         }
92.         else if (!Input.GetKey("left"))
93.         {
94.             isWalkingleft = false;
95.         }
96.      
97.         if (isWalkingleft)
98.         {
99.             Vector3 direction = new Vector3(-head.transform.forward.z, 0, head.transform.forward.x).normalized * speed * Time.deltaTime;
100.             Quaternion rotation = Quaternion.Euler(new Vector3(0, -transform.rotation.eulerAngles.y, 0));
101.             transform.Translate(rotation * direction);
102.         }
103.  
104.         if(freezeYPosition)
105.         {
106.             transform.position = new Vector3(transform.position.x, yOffset, transform.position.z);
107.         }
108.     }
109. }

In this video when I press the down key then the movement is like laggy.

Thank you in advance for your help !