Manage URL routes in own php framework

I'm creating a PHP Framework and I have some doubts...

The framework takes the url in this way: http:/web.com/site/index

It takes the first parameter to load controller (site) and then loads the specific action (index).

If you've installed the framework in a base URL works ok, but if you install it in a subfolder like this: http://web.com/mysubfolder/controller/action

My script parses it as controller = mysubfolder and action = controller.

If you have more subfolders the results will be worst.

This is my Route code:

Class Route
{
    private $_htaccess = TRUE;
    private $_suffix = ".jsp";

    public function params()
    {
        $url='';

        //nombre del directorio actual del script ejecutandose.
        //basename(dirname($_SERVER['SCRIPT_FILENAME']));

        if($this->_htaccess !== FALSE):
            //no está funcionando bien si está en un subdirectorio web, por ej stynat.dyndns.org/subdir/
            // muestra el "subdir" como primer parámetro
            $url = $_SERVER['REQUEST_URI'];
            if(isset($_SERVER['QUERY_STRING']) && !empty($_SERVER['QUERY_STRING'])):
                $url = str_replace("?" . $_SERVER['QUERY_STRING'], '',$url);
            endif;
        else:
            if(isset($_SERVER['PATH_INFO'])):
                $url = $_SERVER['PATH_INFO'];
            endif;
        endif;

        $url = explode('/',preg_replace('/^(\/)/','',$url));
        var_dump($url);

        var_dump($_GET);

    }
}

Thanks for any help you can give.