Defaulting People Picker in aspx pages to Current User

<script type="text/javascript">
_spBodyOnLoadFunctionNames.push("fillDefaultValues");

function fillDefaultValues()
{
fillPeoplePickerWithCurrentUser('Submitted_x0020_By');
}

function fillPeoplePickerWithCurrentUser(pickerName)
{
//get the current user from the welcome menu
var currentUser = getCurrentUser();

//check to see that we've got it
if(currentUser != null)
{
//get the people pickers input div
var pp = getPickerInputElement(pickerName);
//set it to the current user if we've found it
if(pp != null)
pp.innerHTML = currentUser;
}
}

function getCurrentUser()
{
var tags = document.getElementsByTagName('a');
for (var i=0; i < tags.length; i++)
{
if(tags[i].innerText.substr(0,7) == 'Welcome')
{
return tags[i].innerText.substr(8,tags[i].innerText.length);
}
}
}

function getPickerInputElement(fieldsInternalName)
{
var result = "";
var divs = document.getElementsByTagName("DIV");
for(var i=0; i < divs.length ; i++)
{
if(divs[i].id=="WebPartWPQ2")
{
var tds = divs[i].getElementsByTagName("TD");
for(var j=0; j < tds.length; j++)
{
var cellHTML = tds[j].innerHTML;
if(cellHTML.indexOf('FieldInternalName="' + fieldsInternalName + '"') >= 0)
{
var innerDivs = tds[j].getElementsByTagName("DIV");
for(var k=0; k < innerDivs .length; k++)
{
if(innerDivs[k].id.indexOf("UserField_upLevelDiv") > 0)
{
result = innerDivs[k];
break;
}
}
}
}
}
}
return result;
}
</script>