Spool Calibration; Prerequisites - Danfoss PVED-CLS User Manual

ENGINEERING TOMORROW
Automatic adjusted
maximum steering
angles (steering right)
P3838
P3837
P3836
9.2

SPOOL CALIBRATION

As per default, a PVED-CLS will boot up in spool calibration service mode after a successful WAS calibration has been
completed. From here the operator can choose to use the spool auto-calibration routine from the Danfoss PLUS+1
SERVICE TOOL or perform a manual spool calibration, using the direct output control function.
The PVED-CLS shall be calibrated to the OSPE, EHI or EHPS valve in order to achieve optimum and consistent steering
performance in terms of auto-guidance precision and quick steering performance.
A valve can be calibrated in more ways. Common for all the procedure is that the goal is to:

Find the optimum minimum spool position set-points for closed-loop wheel position control

Find the optimum minimum spool position set-points for open-loop flow control
Danfoss recommends using the direct spool control to find the optimal closed-loop dead-bands. When these have
been determined, a constant steady movement of the wheels relationship can be found, hence how many degrees
the wheels turn per second. This relationship is to be used as acceptance criteria, when designing the Auto-
calibration parameter-set.
Example:
Using direct output control, two closed loop dead-band values has been found (P3166 = -90; P3168 = 100), and a
constant steady movement of the wheels relationship has been measured (2° per second).
When designing the Auto-calibration parameter set, use the maximum closed loop dead-band value as your Spool
calib initial spool position (P3802 = 100) and use the constant steady movement of the wheels relationship (2° per
second) for setting the following 3 parameters:

Spool calib +/- turn range sweep (e.g. P3804 = +/- 2,5°, hence P3804 set to 25)

Spool calib max time for acceptable CL DB edge (e.g. P3806 = 3 seconds, hence P3806 set to 30)

Spool calib min time for acceptable CL DB edge (e.g. P3808 = 2 seconds, hence P3808 set to 20)
The acceptance criteria (P3806 and P3808) with a given range (P3804) is up to the OEM to decide. Having a narrower
acceptance criteria, gives a more precise dead-band calibration, but could potentially take longer time to tune.
9.2.1

Prerequisites

Prior to spool calibration, the wheel angle sensors shall be calibrated, the calibration counters and bit inverted copy
for WAS calibration should be updated and a sufficiently large signal to noise ratio shall be ensured (see chapter 9.1).
0.33 0.67
Figure 18
|Captured right most position – Captured neutral position|
1.00
P3839