Motion Calibration; Introduction; Calibration Of Absolute Encoders - Philips CARDIOMD Service Manual

Motion Calibration

4.4 Motion Calibration

4.4.1

Introduction

CardioMD has four independent axes of motion. These are:
•
Detector rotate
•
Detector Y (vertical)
•
Detector X (horizontal)
•
Table longitudinal.
The table axis needs no calibration. One micro switch is used to detect center position. The state
of this micro switch is read by the rotate (master) motion controller and used for automatically
centering of the table as part of patient load positioning.
The other three axes are servo loop controlled by the motion controllers. The position feedback for
these servo loops to the motion controllers comes from high-resolution incremental encoders. As
the encoders are incremental, each of the three axes has an additional absolute encoder mounted.
The absolute encoders – which have less resolution than the incremental encoders – are used to
determine the positions of the axes at power up. That is, when power is applied to the system, the
motion controllers read the absolute position of each axis and use it to index the incremental en-
coders.
The three absolute encoders require calibration after having been replaced or dismounted, or fol-
lowing replacement of any of the vital components in the drive (such as the gear). The procedure
below describes how to calibrate all three encoders simultaneously. However, each encoder may
be calibrated separately.
4.4.2

Calibration of Absolute Encoders

Procedure
First, the system must be placed in the correct
position for calibrating the encoders:
1. Ensure that collimators are mounted on
both detectors.
2. Use the hand controller to move the detec-
tors beneath the table and rotate the detec-
tors to + 90° (detector 1 in vertical posi-
tion and detector 2 in horizontal position).
3. Use a level to verify that the rotate angle
of detector 1 is 90° and the rotation angle
of detector 2 is 0°, relative to horizontal.
4. Remove the gantry base cover.
Note. Detailed instructions for removing the
gantry base cover on CardioMD Series III
systems are provided in Chapter 6 Repair Pro-
cedures.
4-34 CardioMD Service Manual
Details
III
1MAN0158-H11 04-2005 CSIP Level 1