Date: Mon, 7 Jan 2002 08:31:55 -0800
From: Russell E Owen
Subject: RE: 2.5m obslog 20020105 (MJD 52280)
At 6:52 AM -0700 2002-01-07, Pete Newman wrote:
> > During this homing, there were strange problems - it looked
>> to us (using the TPM display of the Galils) that none of the axes got
>> to their commanded positions, yet when the TCC home command returned,
>> it complained only about Mig A.
>
>I think this is normal.  When B and C got home, they stop moving because they
>have hit the home switch. The commanded positions when homing are larger than
>needed.  But only when all commanded axes reach the home switches do the
>commanded and actual values get reset to their nominal values for home
>position.  I think.
Exactly. The first step in homing is to find the reverse limit switch. The Galil is not sure where it is, so it makes a large negative move -- large enough that a working actuator is bound to hit the limit before it finishes the commanded move. Hence if an actuator ever actually GETS to its commanded position while aiming for the reverse limit switch, then that actuator probably is not moving well.
Regards,
-- Russell