Example; Select Ramps With Ramp Time Related To Vehicle Speed - Danfoss pved-cl Operation Manual

Operation Manual
PVED-CL Controller for Electro-Hydraulic Steering, Version 1.38
Steering by High Priority Steering Device – Open Loop
Symbol Index
Sr 3y17
Lr 3y19
Lf 3y20
Tro 3y21
Tfo 3y23
YsetFr 3y32
Tfr 3y33
YAbortDownRamp 3y34
The discontinuities in the progressive characteristic are located at 50, 120 and 333 ([5.0;T at 25], [12,0;T at 50] and [33.3;T at 75] of max port flow
capacity)

Select Ramps with Ramp Time Related to Vehicle Speed

66 | © Danfoss | May 2016
Use this optimization criterion: Ramp down as fast as possible for flow ranges, where jerks are not
significant. Typical values are 1-50 ms. The fast ramp down time shall always be less than the slow ramp-
down time. Once the value is set, it should not be adjusted anymore during further ramp parameter
optimization.
YAbortDownRamp To come around the problem of slow steering response for large down-ramp times,
especially if a sudden emergency change of direction is needed, a slow down-ramp can be aborted by
requesting a flow in the opposite direction. Once a slow down-ramp is aborted, an abort down-ramp
time, Tra is applied. Obviously Tra shall be significantly smaller than the slow down-ramp to get any
effect.
Tra is the ramp-down time applied when the slow down-ramp is aborted. This rampdown time shall
typically be much lower than the slow ramp-down time, Tfo, in order to gain any increased steering
responsiveness. Typical value is half the value of Tfo or Tfh time if vehicle speed dependency is applied
(Sr=2). Use trail and error.

Example:

A value equal to 500 means that the driver needs to steer out 500/1000 of maximum flow before the slow
down-ramp is aborted. 500 again corresponds to a certain steering wheel RPM.
Typical values are 100-300 to have the abort down ramp possibility and to avoid unintentional abort of
the down ramp due to steering wheel activation due to vibrations. Setting the value to 1000 disables the
abort down ramp functionality.
Default Value range
0 Must be set at 1
0 0 (linear) to 10 (max progressive)
0 0 to 10
1 1 to 1000 (ms)
350 1 to 1000 (ms)
1000 0 to 1000 (1 unit = 0.1% of max. flow)
100 1 to 1000 ms
Tfr shall be smaller than Tfo and less than 150 ms.
0 0 to 500 (1 unit = 0.1% of max. flow).
The default value will force an down-ramp abort at a slight reverse port flow request.
Typically YAbortDownRamp needs be increased to avoid unintentional down-ramp
aborts as this will infer a jerk on the driver.
To optimize the anti-jerk performance to different work cycles, the vehicle speed can be used to derive
ramp times by interpolation between ramp values for 0 km/h.
11025583 | AQ00000216en-US0302