3D: how to avoid jerks in a character movement using accelerometer

hi, I have a animated bird flying at constant speed, bird moves with the movement of mobile (left, right). when i slowly move the mobile the bird movement is perfect but when mobile movement on left right is fast the bird movement is in jerks. I also use a float variable filter to avoid jerks but its not working i guess. here is my code.....!

     private float speed = 10.0f;
     private float filter = 5.0f;
 
     private int maxX = 3;
     private int minX = -3;
 
     
     private Vector3 accel;
     
     void Start(){
         accel = Input.acceleration;
     }
     
     void Update(){
         GetComponent<Rigidbody> ().AddForce (new Vector3(1000,0,0), ForceMode.Acceleration);
         // filter the jerky acceleration in the variable accel:
         accel = Vector3.Lerp(accel, Input.acceleration, filter * Time.deltaTime);
         
         Vector3 dir = new Vector3(accel.x, 0, 0);
         // limit dir vector to magnitude 1:
         if (dir.sqrMagnitude > 1) dir.Normalize();
         // move the object at the velocity defined in speed:
         transform.Translate(dir * speed * Time.deltaTime);
         Vector3 pos = transform.position;
         // clamp new position:
         pos.z = Mathf.Clamp(pos.z, minX, maxX);
         //pos.y = Mathf.Clamp(pos.y, minY, maxY);
         // and assign it to the object:
         transform.position = pos;

any help would be appreciated.