From: "James Lerch" 
To: 
Cc: "ATM List" 
Reply-To: "James Lerch" 


Hello Again,

A suggested, I ran a micrometer test against the longitudinal axis of Robo2 today.

Here's a picture of the setup:
http://lerch.no-ip.com/atm/2ndTry/Robo2/Robo_V_Micro/Setup.jpg (56KB)

Here's the results in an Excel File:
http://lerch.no-ip.com/atm/2ndTry/Robo2/Robo_V_Micro/Robo_V_Micro.xls
(41KB)

If interested you can browse the raw images from here: (which show the
micrometer reading and an on-screen display of the commanded amount of
motion) http://lerch.no-ip.com/atm/2ndTry/Robo2/Robo_V_Micro/Raw_JPG/

For those that just want the answer without opening a web-browser, Robo2
shows 0.003" periodic error every 0.050" of longitudinal travel.

Over a the range of positions from 0" to 0.398" Robo2 shows
-0.005" of travel error.  Most likely this is miss-allighnment of the
micrometer axis with the longitudinal axis of Robo2.

In addition Robo2 shows 0.006" of backlash in the longitudinal axis, fortunately
Robo software automatically compensates for up to 0.020" of backlash
during an auto-test (btw, this amount is user selectable.)

When the longitudinal axis is held constant, and the lateral axis is moved
0.05", ~0.001" of change in longitudinal reading was noted
(mostly when reversing the direction of travel)

Here's the procedure for the test, with the goal of simulating the method
used during a normal automated test.

A command button was added to the Robo code.  The command button when
selected did the following:

#1 Saved the current image
#2 Moved 0.002 longitudinally using the same code used in the auto-test
#3 Waited 1 second for image acquisition and stabilization
#4 Repeated for 200 positions (0-0.398")

For those "Really Curious"  Here's the actual code used
to perform the test:

Private Sub Command4_Click()
Dim SfileName As String
Dim dummy As Long
Dim delay As Long
Dim i As Long

For i = 1 To 200

    SfileName = "C:\rtaft\Time" & Format(Time,
"hhmmss") & "Pos" & _
                            Format$(Round(Ypos * StepSize, 4),
"0.000") &
".bmp"

    SavePicture Picture1.Image, SfileName

    For dummy = 1 To TFRoughMove
             Y = Y - 1
             If Y < 0 Then Y = 7
             Ypos = Ypos + 1
         Out &H378, (coil(x, Abs(mnuinvert.Checked), Abs(mnuLRswap.Checked), _
                               Abs(mnuSwapMotors.Checked)) + coil(Y,
Abs(mnuinvert.Checked),_
                               Abs(mnuTFswap.Checked), Abs(Not
(mnuSwapMotors.Checked))))
        delay = 0

        Do While delay < Mindelay.Value * 3
            delay = delay + 1
        Loop
        DoEvents

    Next dummy

    For dummy = 1 To 30
        capGrabFrameNoStop lwndC
        Call Plot_Zones
    Next dummy

Next i
End Sub

Take Care,
James Lerch
http://lerch.no-ip.com/atm (My telescope construction,testing, and coating site)

"Anything that can happen, will happen" -Stephen Pollock from:
"Particle Physics for Non-Physicists: A Tour of the Microcosmos"

--- BBBS/NT v4.01 Flag-5