Character movement with Babylon.js

In the game demo I am placed in a school, I need to move my character using the WASD keys as well as the arrow keys. I set up a function and set a toggle case to listen for any key press. Here is my code snippet:

//Handles the player movement
var PlayerMovement = (function () {
    //Constructor
    function PlayerMovement() {
        this.gameObject = null;
        this.movementSpeed = 0;
        this.rotationSpeed = 0;
    }

    PlayerMovement.prototype.awake = function () {
        console.log("Awake");
    };

    PlayerMovement.prototype.update = function () {
        //console.log(Tools.getFps());
    }

PlayerMovement.prototype.onKeyPressed = function (key) {
        switch(key)
        {
            case KeyType.W:
            case KeyType.UpArrow:
                console.log("Moving up");
                this.gameObject.meshObject.position.z += (BABYLON.Vector3.Up() * this.movementSpeed * Tools.getDeltaTime());
                break;
            case KeyType.A:
            case KeyType.LeftArrow:
                //TODO: Do stuff
                break;
            case KeyType.S:
            case KeyType.DownArrow:
                //TODO: Do stuff
                break;
            case KeyType.D:
            case KeyType.RightArrow:
                //TODO: Do stuff
                break;
        }
    }
 return PlayerMovement;
})();

      

        
        
        
      

    

My problem is my character jumps so far forward that it disappears from the screen. Can anyone help me figure out what is wrong with my calculations?