Ql
(Ff)
saturates
100
200
300
400
500
0
100
200
300
400
500
Off
Ff - Feedforward
700
800
900
600
1000
P005 219E
0
600
700
800
900
1000
M
ax p
or
t flo
w Ql
(Ff
)
Qm
Example
Off=300
Qm=900
defaults
Off=100
Qm=1000
Ql
(Ff)
= |Ff| * 1.33+Off
Off Sets max port flow at zero feed forward. Setting the parameter equal to Qm disables the variable
proportional band.
The default value is set at 10% of max port flow, which is sufficient to counter act disturbances in steady
state and to control the steering actuator at low steering wheel speeds.
Qm Sets max port flow. It cuts-off the function and defines hereby the maximum speed of the steering
actuator to approach the set point position.
Kp This parameter is closely related to valve capacity, stroke volume and 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
•
Low and near max steering pressure when driving at low, high vehicle speed
and reversed gear. The default value fits to steering systems with a lock-to-
lock time of 2 seconds at max port flow.
Symbol
Index
Default
Value range
Kp
108
50
0 to 200 (0.00 to 2.00% of port flow capacity per 0.1 % positional error)
Qm
1y27
1000
0 to 1000 (0.0 - 100.0% of max port flow)
Off
1y28
100
0 to 1000 (0.0 - 100.0% of max port flow)
StrkVol
707
600
10 to 8000 ccm
In order to ensure convergence, check that variable Yact is increasing for positive values of port flow.
Open loop control can be used to check this. To retrieve this data, use StartStopStatus and request status
data set number 2. See PVED-CL Communication Protocol. The PVED-CL will return the status data with ~
40 ms intervals.
This function will continuously minimize the steering wheel drift that is build up and which results in
misalignment of the straight direction indication on the steering wheel and the actual driving direction.
The absolute steering wheel sensor position 0 defines the straight direction. Aligning the steering wheel
sensor with straight driving direction can be achieved by orienting the SASA sensor to output position 0
when the steering wheel and steering actuator are in straight position. Alternatively the SASA sensor
position 0 can be programmed after physical installation. Refer to
CAN message Protocol in OSPE Steering
Valve, SASA Sensor, Technical Information
, 11068682.
Steering Wheel Knob Position Control
This function relates the absolute steering wheel position to the position of the steering actuator
Operation Manual
PVED-CL Controller for Electro-Hydraulic Steering, Version 1.38
Steering by Steering Wheel – Closed Loop
©
Danfoss | May 2016
11025583 | AQ00000216en-US0302 | 57