wp_insert_post is not creating revision in database

Hi,
I am creating custom frontend post submission form. I am using wp_insert_post for creating new post. The function is working fine but it is not creating the revision record in database.

Following is my code. I want record of every revision made in the post. Plz Help… Thanks…

<?php

if (isset($_POST['submit_post']) ) {

  $my_post = array(

      'post_title'   => wp_strip_all_tags( $_POST['post_title'] )

  );

  wp_insert_post( $my_post );

}

?>

<form method="POST">

  <div class="form-group">
    <label for="post_title">Post Title</label>
    <input type="text" class="form-control" name="post_title" placeholder="">
  </div>

  <button type="submit" name="submit_post" class="btn btn-default">Submit Post</button>

</form>