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© Danfoss | August 2018 AQ00000211 |
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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 ( ) curve.
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 ( ) in Figure 43 and more smoother ramps will be
applied to minimize the jerks in the system.
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 43
S1
S2
Sa1
Sa2
Sa3