Anti-Jerk - Danfoss PVED-CLS User Manual

ENGINEERING TOMORROW
10.6

ANTI-JERK

Jerk is a common unpleasant feeling/phenomenon, which can be experienced on large, articulated vehicles. To minimize
these jerks, the PVED-CLS has a built-in anti-jerk algorithm which can be enabled and parameterized.
Briefly, the Anti-jerk algorithm has two sets of parameters to choose from, one set for when moving away from neutral
position and one set for moving towards neutral position.
In the Figure below, point S1 shows the current spool position and S2 shows the calculated flow command to PVED-
CLS. The point Sa1, Sa2 and Sa3 shows adjusted flow set-points after applying anti-jerk algorithm. When the spool is at
point S1 and when there is jerk in the system, the flow set-point S2 is calculated and is expected to reach S2 in one cycle
which is shown by dotted line (
The anti-jerk algorithm calculates the 'adjusted flow set-points' Sa1, Sa2 and Sa3 based on relative or absolute set-point
changes in one cycle i.e. in 10 ms which is shown by line (
applied to minimize the jerks in the system.
CalculatedFlowSetpoint_IR Anti-jerk function
Anti-jerk function
Flow Command
S1
Sa1
Sa2
S2
Neutral
1 2 3
10ms 10ms
© Danfoss | August 2018
) curve.
AdjustedFlowSetpoint_IR
Sa3
4 5 6 7 8
Figure 43
) in Figure 43 and more smoother ramps will be
Soft-stop Requested flow set-point
Absolute, out (changed from
Absolute, out; (P3574)
absolute in, due to crossing neutral)
Relative, out (changed from
Absolute, in; (P3576)
relative in, due to crossing neutral)
Relative, out; (P3572)
Relative, in; (P3573)
Flow to spool pos
Spool pos. Set-point
conversion
Adjusted flow set point
Flow command to PVED-CLS
Ramps
cancelation
Control loop
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