致命错误:在joomla2.5中对非对象调用成员函数get()

我正在创建一个joomla2.5模块。我想从模块中检索通过参数的数据，但我得到关于标题错误。下面是我的代码:helper.php

class modFeedGrabber
{
    function feedurl(){
        $url = $params->get('feedUrl');
        return $url;
    }
    function maxCount(){
        $maxcount = $params->get('maxCount');
        return $maxcount;
    }
    function showDesc(){
        return $params->get('showDesc');
    }
    function showPubDate(){
        return $params->get('showPubDate');
    }
    function targetLink(){
        return $params->get('titleLinkTarget');
    }
    function descChar(){
        return $params->get('descCharacterLimit');
    }
    function fx(){
        return $params->get('fx');
    }
    function delay(){
        return $params->get('delay');
    }
    function timeout(){
        return $params->get('timeout');
    }
    function module_sfx(){
        return $params->get('moduleclass_sfx');
    }
}

mod_feedGrabber.php

defined( '_JEXEC' ) or die( 'Restricted access' );
$sitebase = JPATH_BASE;
$doc =& JFactory::getDocument();
// Include the syndicate functions only once
require_once( dirname(__FILE__).DS.'/helper.php' );
$feed = new modFeedGrabber();
$url = $feed->feedurl($url);
$maxcount = $feed->maxcount($maxcount);
require( JModuleHelper::getLayoutPath( 'mod_feedGrabber' ) );

我的新问题是如何从模块获得数据传递?