Ramps (Anti-Jerk); Ramps With Fixed Ramp Times - Danfoss pved-cl Operation Manual

Operation Manual
PVED-CL Controller for Electro-Hydraulic Steering, Version 1.38
Steering by Steering Wheel – Open Loop
Symbol
Vcap
StrkVol
Sse
Sts0
Sts1
Sts2
Sts3
Sts4
Sts5
Vesm
Please note the parameter dependency of Sts. Steering sensitivity of 400 equals to 4.00 steering wheel turns to move the steering actuator from YL to
YR (left to right end-lock position) See chapters
speed.

Ramps (Anti-jerk)

Ramps with Fixed Ramp Times

Symbol Index
Sr 1y17
44 | © Danfoss | May 2016
Sts3 sets the steering ratio when the vehicle is driving at 25.00% of Vesm.
Sts4 sets the steering ratio when the vehicle is driving at 50.00% of Vesm.
Sts5 sets the steering ratio when the vehicle is driving at 100.00% of Vesm.
Vesm sets the region where steering sensitivity is variable to vehicle speed. The default value is set at the
maximum speed of most applications.
Index Default
706 25
707 600
1y09 1
1y10 400
1y11 400
1y12 400
1y13 400
1y14 400
1y15 400
1y16 500
Mapping a Steering Device
Ramps are normally used to minimize jerk forces in machines with articulated steered steering systems. In
these steering systems, the articulating masses can be instantly stopped by closing the valve oil flow. An
instant cylinder movement stop starts the articulating masses to oscillate until all kinetic energy is
dispatched into heat by the shock valves or by the friction between wheels and ground. Jerk is an
inherent characteristic of articulated steered vehicles and cannot be completely removed. However, it is
best minimized when the forces are monotonically reduced in magnitude.
To achieve this, the EHPS software provides linear or non-linear ramps which in effect creates an orifice
across the main spool to tank by holding the valve open near its closing position until all kinetic energy is
dispatched into heat for some time. Ramps work on the valve spool set-point.
Sr sets the method. The ramp times can be disabled, fixed or related to vehicle speed. Set Sr to:
•
0 to select no ramps (default),
•
1 to select fixed ramp times, or
•
2 for speed dependent ramp times.
Default Value range
0 0 (default)
The figure below shows the operation of ramps with fixed ramp times and illustrates different ramp
scenarios. Qr is the request port flow commanded with the steering wheel. Qramp the ramp limited port
flow and can be regarded as the result of the ramp function.
Value range
5 to 120 (L/min)
100 to 8000 (ccm)
Must be set at 3
20 to 1200
Sts0 to 1200
Sts1 to 1200
Sts2 to 1200
Sts3 to 1200
Sts4 to 1200
1 to 1000 (0.0 to 100.0 km/h)
on page 31 and J1939 Diagnostic Interface on page 102 to acquire vehicle
11025583 | AQ00000216en-US0302