Danfoss PVED-CLS, User Manual, Page: 104 / 182

104 | © Danfoss | August 2018 AQ00000211
ENGINEERING TOMORROW
Anti-jerk function
Flow Command
Control loop
1 2
Absolute, in; (P3576)
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)
10ms 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.
S1
S2
Sa1
Sa2
Sa3