Closing The Loop; Eliminate Noise Due To Frequent Pressure Build-Up - Danfoss pved-cl Operation Manual

Operation Manual
PVED-CL Controller for Electro-Hydraulic Steering, Version 1.38
Steering by Low Priority Steering Device – Closed Loop
Symbol Index
db 4y05
Lx 4y06
YR 4y07
YL 4y08
Yxsat 4y03
Parameter Yxsat, db & Lx have same value in quadrant 2 & 3.
Lx in quadrant 1 or 4 is located at: [(Xysat+db)/2;YR*(20-Lx)/40].
Lx in quadrant 2 or 3 is located at: [-(Xysat+db)/2;YL*(20-Lx)/40].

Closing the Loop

Symbol Index
Kp 408
Qm 4y27

Eliminate Noise due to Frequent Pressure Build-up

Symbol Index
Tclpout 417
Qth 418
© Danfoss | May 2016
end lock. This results in steering to the right direction. In case an opposite steering behavior is required,
YR must be set at the negative equivalent and YL must be set at the positive equivalent (See example).
The default value for YR and YL is set equal to the mechanical locks of the steering actuator resulting in
the vehicle to steer in the right direction.
Yxsat Sets a threshold for the output to be at its maximum or minimum when the input signal exceeds
the threshold value. Yxsat is normally set down when more sensitivity is required than inherently
available with the steering device.
The default value will not effect the inherent sensitivity of the steering device.
Default Value range
0 0.0 to 250 (0.0 to 25.0% of max activation in the right steering direction)
0 -10 to 10 (-10 max regress, 0 linear, 10 max progress)
1000 -1000 to 1000
-1000 -1000 to 1000
1000 251 to 1000
Kp Amplifies the error between set point and current position. The optimum value for Kp is found when a
non-lagging, accurate, non-oscillating steering actuation without overshoot is achieved at extreme low
and high oil viscosities as specified in chapter: (robustness to changes sin dead times) and at low and
near max steering pressure when driving at low, high vehicle speed and reversed gear (robustness to
changes in damping & dead times). Moreover, Kp is closely related to valve capacity, stroke volume. See
section Steady State Error on page 56 for information on accuracy. The default value fits to steering
systems with a lock-to-lock time of 2 seconds at max port flow.
Qm Sets the maximum port flow. It effects the speed of the steering actuator to move towards the set
point position. Negative values of Qm are interpreted as the positive equivalent.
The default value is set equal to the inherent max port flow capacity of the valve and will therefore not
have any effect.
Default
50
1000
Eliminating noise is accomplished by stopping the controller to respond to minor deviations between set
point and current actuator position. The spool inside the valve is set in neutral when the port flow
command has been within a threshold value (Qth) for a given time (Tclpout). The spool is reactivated
again when port flow command exceeds the threshold.
Tclpout Sets the time delay (ms) before the main spool is set in neutral.
Qth Sets the threshold value for port flow command when the controller is in steady state.
Default
3000
50
Value range
0 to 200 (0.00 to 2.00% of port flow capacity of the valve for 0.1% positional
error)
0 to 1000 (0.0 to 100.0 % port flow)
Value range
1 to 30000 (ms)
0 to 100 (0.0 to 10.0% of max port flow)
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