104 | © Danfoss | August 2018 AQ00000211
Anti
-jerk function
Flow Command
Control loop
1 2
Absolute
, in
;
(P
3576
)
3 4
5 6
7
8
Adjusted flow set point
Flow command to PVED
-CLS
Absolute,
out;
(
P3574)
Relative, out; (P3572)
Relative, in; (P3573)
Neutral
Ramps
cancelation
Absolute
, out (
changed from
absolute in,
due to crossing neutral
)
Relative, out (changed from
relative in, due to crossing neutral)
10
ms
10ms
Anti-
jerk function
CalculatedFlowSetpoint_
IR
AdjustedFlowSetpoint_IR Soft-stop Requested flow set-point
Flow to spool pos
conversion
Spool pos.
Set-point
Figure 52
11.6.1 Calculation of flow set-point using anti-jerk functionality
The anti-jerk algorithm uses relative set-point parameters P3699 and P3700 in [%] and absolute set-point parameters
P3701 and P3703 in [IR] and detects the relative or absolute set-point changes in one loop/cycle (10ms). The algorithm
will chose the parameter (absolute or relative) which has the highest change of set-points for each loop (i.e. 10ms) and a
new ‘modified flow set-point’ is calculated. Finally, the low pass filter is applied on the ‘modified flow set-point’ to
calculate the ‘filtered flow set-point’.
The low pass filter in the function is configurable by P3718 (default cut-off frequency is 10Hz, i.e. P3718 set to 100).
If the EH-spool is commanded to go from left- to right-side or opposite, when crossing neutral, the ramps will be
canceled and the parameter set will change from “moving towards neutral position” to “moving away from neutral
position”.
For the relative set-point parameters (P3699 and P3700), the value will change depending on the actual spool position.
For the absolute set-point change parameters (P3701 and P3703), the value will always be a fixed set-point value,
parameters shall be configured accordingly.
Important
An anti-jerk function is normally only used on articulated vehicles, where jerk is very common.
Important
Jerk is a sideways hard movement around the articulated point. This Anti-Jerk functionality will minimize the
unpleasant sideways movement around the articulated point.
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