Sum Columns Using Powershell

I have written the following PowerShell script for getting disk space information for servers in our environment.

$servers =Get-Content E:\POC.txt
$array =@()foreach($server in $servers){
    $sysinfo =Get-WmiObjectWin32_Volume-ComputerName $serverfor($i =0;$i -lt $sysinfo.Count; $i++){
        $sname =  $sysinfo[$i].SystemName
        $servername = $server
        $label = $sysinfo[$i].Labelif(($label)-and(!($label.Contains("FILLER")))){
            write-host "Processing $label from $server"
            $name = $sysinfo[$i].Name
            $capacity =[math]::round(($sysinfo[$i].Capacity/1GB),2)
            $fspace =[math]::round(($sysinfo[$i].FreeSpace/1GB),2)
            $sused =[math]::round((($sysinfo[$i].Capacity- $sysinfo[$i].FreeSpace)/1GB),2)
            $fspacepercent =[math]::Round((($sysinfo[$i].FreeSpace*100)/$sysinfo[$i].Capacity),2)
            $obj =New-ObjectPSObject
            $obj |Add-Member-MemberTypeNoteProperty-Name"SystemName"-Value $sname
            $obj |Add-Member-MemberTypeNoteProperty-Name"ServerName"-Value $server
            $obj |Add-Member-MemberTypeNoteProperty-Name"Label"-Value $label
            $obj |Add-Member-MemberTypeNoteProperty-Name"Name"-Value $name
            $obj |Add-Member-MemberTypeNoteProperty-Name"Capacity(GB)"-Value $capacity
            $obj |Add-Member-MemberTypeNoteProperty-Name"FreeSpace(GB)"-Value $fspace
            $obj |Add-Member-MemberTypeNoteProperty-Name"Used(GB)"-Value $sused
            $obj |Add-Member-MemberTypeNoteProperty-Name"FreeSpace%"-Value $fspacepercent
            $array += $obj}}
    $array += write-output " "
    $totalSize =($array |Measure-Object'Capacity(GB)'-Sum).Sum
    $array += $totalsize
    $array += write-output " "}
$filename ="E:\VolumeReport.csv"
$array |Export-CSV $filename -NoTypeInformation

One additional requirement here is to get the sum of the columns for Capacity, Size and Freespace for each server. I tried using Measure-Object but no success. No values are getting outputted here. Just blank. Please look into this and kindly assist.