URL Redirect – How to Redirect to Form Submission Page from Controller

I implemented a Form with a submission treatment by controller.

At the end of the treatment, I would like to redirect to the form submission page.

I tried several things :

$this->_redirect('*/*/');

and

$this->_redirectReferer();

I also tried to place the form submission url in the form by adding :

<input name="redirect_url" type="hidden" value="<?php echo $this->helper('core/url')->getCurrentUrl() ?>" />

and in the controller :

$post = $this->getRequest()->getPost();
…
$this->_redirect($post['redirect_url']);

But none of these solutions are working…
Any help please?