Canon Omnera 500A Operator's Manual page 50

Safety
Safety functions
Note!
In some situations it is possible to force a false detection of a collision. This can occur if the
column is affected by a pressure at the time the movement starts. This could be for example
the case if the collimator rests on the Table, when the operator moves the column upward, a
collision is detected.
The reason for the collision detection is that, when the movement starts, the zero force level
is calculated based on the actual pressure affecting the column at that moment. As soon as
the movement starts and the collimator is no longer resting on the Table, the guard plate
catch a change in pressure and a collision is detected.
To solve the problem the operator must affect pressure on the column, for example manually
pull the column up or down. The System will take this as a sign that the operator has re-
moved the obstacle and that no collision exists any more. If the problem is yet not solved, the
System must be restarted.
Motor node
Every motor node has a collision detection on their own movements. A collision can be de-
tected in different ways, for instance, if:
• The control error in the motor node's regulator is too large.
• The final position is not reached in time.
• The position transducer has not moved although the drive unit has had an output voltage
for a given time.
A detected collision makes the stand stop all movements and display an error message.
Quick abortion of an auto positioning
When any of the buttons on the stand is pressed while the stand is moving toward its posi-
tion, it has the same effect as when the servo button is released, all movements are stopped.
Opposite buttons pressed
If, at any time, two from each other opposite buttons are pressed, for example movements
up and down, the movement is stopped. Both buttons must be released before any move-
ment is allowed.
2.12.1.2 Malfunctioning Node
If any node stops functioning, all movements are stopped and the power to the motors in the
System is removed.
2.12.1.3 Dead man's grip
All movements require constant activation of the chosen button.
If the operator releases one of the buttons/controls, the system will immediately stop or en-
gage the brakes (manual movements). The exposure operator console has the same
functionality.
2.12.1.4 Watchdog
One important issue for the safety in the system is the node error handling e.g. transmission
error, software error or irregular behaviour of a node. The system is built to prevent an un-
controlled movement.
The design relies on two different constructions to have a safe communication and safe error
handling.
OMNERA® 1000-095-071-EN Rev. 1.1
Page 42
Operator´s Manual
2020-09-14