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Block diagram closed loop steering wheel steering
Transfer
function
Kp
Port flow
limiter
Qm
actuator
position
Port flow
command
Yr,Yl,Lx
10 ms
Anti
windup
Steering
sensitivity
Sse,
Sts0,Sts1,Sts2,Sts3,
Sts4,Sts5, Vesm
Vehicle
speed
100 ms
Feed-
forward
Anti drift
Backlash
Kd,Kc
Ri
10 ms
10 ms
delta
angle
Steering
wheel
angle
Select the Control Principle
Cp selects the closed loop control for steering wheel steering. Parameter index 1y02 must be set equal to
255. Parameter selection values: Y selects the program and ranges from 0 and 9.A fixed value of Y must
be consistently used throughout the entire configuration of a single program.
Acquire the Signals
See
on page 31 on how to map the steering wheel sensor and steering wheel
angle sensor.
Apply Backlash
Ri If elasticity affects the sensor readings when the driver releases the steering wheel and hereby
unintentionally operates the valve, a backlash region (Ri) can be applied to prevent it. The size of the
backlash region is normally set equal to the angle related to elasticity.
However, any set-value greater than zero leads to slower steering responds. Therefore, to minimize these
effects, the steering wheel, sensor shaft and underlying mechanics as shown below must be designed as
stiff as possible.
Sensor
Steering wheel
Since this parameter only effects changes in the set point, stability problems in closed loop are not
related to the set-value of this parameter.
The default value does not remove elasticity effects.
Symbol
Index
Default
Value range
Ri
1y04
0
0 to 200
0 means 0 degrees backlash, 200 means ~17 degrees backlash. Backlash applies in both steering directions; therefore the total backlash region is twice
the threshold.
Steering Sensitivity
Sensitivity is set individually for each program and can be either fixed or variable. Variability can depend
on vehicle speed or change of current device program.
Using variable sensitivity can increase comfort and drivability significantly, and depending on the vehicle
type and use the appropriate way to achieve the change might be different.
The PVED-CL allows several programs for each steering device, which means that 5 to 10 different
programs with different sensitivity settings can be made and applied via the MMI while driving. Each
program can then use either fixed or variable sensitivity – hence we talk ‘second-order-variability’ by
using the PVED-CL.
Operation Manual
PVED-CL Controller for Electro-Hydraulic Steering, Version 1.38
Steering by Steering Wheel – Closed Loop
©
Danfoss | May 2016
11025583 | AQ00000216en-US0302 | 53