Open Loop Mini-Wheel Anti-Drift (Efu) - Danfoss PVED-CLS User Manual

ENGINEERING TOMORROW

11.5 OPEN LOOP MINI-WHEEL ANTI-DRIFT (EFU)

The anti-drift function is implemented for eliminating internal leakage errors and for having the steering wheel in the
same position when driving straight ahead. The functions control algorithm will determine the correct output flow
(ccm per revolution) by adding an anti-drift correction portion to the calculated ideal ccm per revolution-output.
The anti-drift correction portion is calculated by looking at the difference, in degrees, measured at the steering wheel
and the actual position of the wheels. The percentage of the full flow, which PVED-
is defined by the following four points, Point A to Point D, where Point B and Point C are configurable.

Point A (0, 0)

Point B (P3706, P3705)

Point C (160, P3705)

Point D (0, 0)
AUX - Open Loop Mini Wheel Anti-drift (EFU)
50
45
40
35
30
25
20
Point B
15
10
5
Point A
0
0 10 20
The range is from 1° to 160° for P3706, in steps of 1°. For P3705 the range goes from 0% to 100% in steps of 1%.
The values recommended by Danfoss are P3706 set to 20 and P3705 set to 15 i.e. anti-drift will be enabled all the
time and 15% of the full flow will be added or deducted depending on direction, to the calculated ideal ccm per
revolution-output, when the difference between the measured steering wheel position and the actual position of
the wheels is 20° -
linear interpolation between Point C and the fixed point D, will determine the anti-drift correction portion.
Furthermore, anti-drift function will also improve consistency in lock-to-lock on steering wheel.
30 40 50 60 70
|Mini-steering wheel angle difference [degrees]|
80 90 100 110 120 130 140 150 160 170 180
Figure 39
s anti-drift algorithm will add
Point C
Point D
eel angle difference is > 160°