La fonction upload de codeigniter

<label class="control-label">Select File</label>
<input  type="file" name="image" class="form-control">

$config = array(
array(
				'field' => 'image',
				'label' => 'image de l"evenement',
				'rules' => 'trim',
				));

$this->form_validation->set_rules($config);
if ($this->form_validation->run()) {

	$vi['upload_path'] = '../../assets/avatars/';
	    $vi['allowed_types'] = 'jpg|png';
	    $vi['max_size'] = '2048';
	    $vi['max_width'] = '35';
	    $vi['max_height'] = '20';
	    $this->load->library('upload', $vi);
	    
	    if (!$this->upload->do_upload('image') == TRUE){
	    	echo "string";
	    	return false;
	    }else{
	    	echo "bon";
	    	$u = $this->upload->data();
	    	print_r($u);
	    	return TRUE;
	    }