Spool Calibration Procedure; Determining The Closed Loop Dead-Bands; Determining The Open Loop Dead-Bands - Danfoss PVED-CLS User Manual

ENGINEERING TOMORROW
Name
Max spool position, left P3162 S16
Max spool position,
P3164 S16
right
Closed loop dead-band
P3166 S16
edge, left
Closed loop dead-band
P3168 S16
edge, right
Open loop dead-band
P3170 S16
edge offset
17.6.5.2

Spool calibration procedure

Determining the closed loop dead-bands

The principle in this calibration procedure is to determine the closed-loop mode dead-bands first. The closed-loop dead-
bands are defined as the slowest possible steered wheel movement speed that is used for controlling the smallest possible
wheel angle position error (proportional control). Once the closed-loop dead-bands are determined (P3166 and P3168),
the open-loop dead-bands are derived by subtracting an off-set (P3170) from the respective closed-loop mode dead-band
positions (P1 and P2 from Figure 68)
The following calibration procedure is based on balancing the time it takes to move between two fixed wheel angles by
adjusting two experimental spool position set-point values.
Important
The criteria which shall be evaluated for valve calibration are:
•
The times to move from left to right and vice versa are equal (symmetry measure)
•
The time to move from left to right and vice versa is sufficiently slow (minimum flow)
These above times depends on e.g. vehicle geometry, steering type, cylinder stroke volume, wheel angle sensor
calibration, valve capacity and requirements on minimum correction flows for closed-loop mode operation.

Determining the open loop dead-bands

When the closed-loop mode dead-bands are found, the open-loop dead-bands values (P1 and P2 from Figure 68) are set
by subtracting an offset (defined by parameter P3170) from the closed-loop dead-band values.
The criteria for having derived good open-loop dead-bands are:
•
The valve shall not steer out any flow and therefore the steered wheel shall not exhibit movement jitter when no
steering activity takes place
© Danfoss | August 2018
Description of parameter
x10u Meter Spool left most position
x10u Meter Spool right most position
x10u Meter Spool closed loop dead-band edge, Left
x10u Meter Spool closed loop dead-band edge, Right
x10u Meter Spool open loop dead-band offset
Table 88
Range
OEM, Dealer -1000 -300
OEM, Dealer 300 1000
OEM, Dealer -300 0
OEM, Dealer 0 300
OEM, Dealer 0 150
AQ00000211 | 177
-420
420
-105
105
25