Fda - Danfoss PVED-CLS User Manual

ENGINEERING TOMORROW

FDA

FDA Fault Detection Algorithm is a safety function which can be applied by the operator. To learn more about the
safety aspect in this functionality, please see the Danfoss document, PVED-CLS Safety Manual.
The FDA evaluation is done in 3 steps:
First step: Sensor validation
The input sensors are evaluated using the thresholds defined by parameters in the FDA sector.
For STW it is determined whether its turning left, not turning or turning right by using parameters P3122 & P3133.
For WAS it is determined whether the vehicle is turning left, not turning or turning right by using parameters P3123
& P3124.
For the spool position sensor (LVDT) it is determined whether it is outside left dead-band, inside both dead-bands or
outside right dead-band by using the closed loop dead-bands + P3128 & P3130.
The results of these evaluations are found in status message 5, byte 1, bits 8 3.
Second step: System evaluation
With the information from the sensors the FDA validates whether the state of the system is OK (Yes) or not OK (No)
by using the following truth table:
Sensor validation
Spool position
Steering wheel direction
WAS direction = Left
WAS direction = Neutral
and cylinder close to left
end-stop (WAS IR < -950)
WAS direction = Neutral
and cylinder not close to
end stop
(|WAS IR| <= 950)
WAS direction = Neutral
and cylinder close to right
end-stop (WAS IR > 950)
WAS direction = Right
Whenever the FDA detects a not OK condition, the error condition flag is set. The error condition flag is found in
status message 5, byte 1, bits 2 1.
Third step: confidence counter
Whenever the FDA detects an error condition, the confidence counter is incremented by 10ms (the validation is
done every 10ms). If the system is in a good condition, the confidence counter is decremented by 10ms*P3125.
If the confidence counter hits the roof specified by P3126, the fault condition flag is set and PVED-CLS enters safe
state (unless disabled by parameter P3132). The fault condition flag is found in status message 5, byte 2, bits 2 1.
Warning
Left Left Left
Left Neutral Right
Yes Yes No
Yes Yes No
No No No
No No No
No No No
Table 52
Condition
Neutral Neutral Neutral
Left Neutral Right
Yes No No
Yes Yes No
No Yes No
No Yes Yes
No No Yes
Right Right Right
Left Neutral Right
No No No
No No No
No No No
No Yes Yes
No Yes Yes