How can you implement movement along the walls of the tunnel in a normal way?

Question

Unity

Like now I did this, but it all depends on the dummy on which the character is. I turn it, the character turns. The problem is that if the tunnel turns, the character will fly out of it. And in general, it's somehow very difficult, you need to put the dummy in the middle of the tunnel, and the player on the surface of the tunnel.

Video

Hierarchy:


The code is on the Player object:

The code

void FixedUpdate ()
  {
    transform.position += transform.right * Time.fixedDeltaTime * force;

    Vector3 acceleration = Input.acceleration;

      transform.Rotate(new Vector3(acceleration.x * sidewaysForce * Time.fixedDeltaTime,0,0));

  }