Main Spool Dead-Band Control Function; Dead-Band Jump Control; Dead-Band Hold And Proportional Control; Responding To Flow Requests After Tolsout - Danfoss pved-cl Operation Manual

Operation Manual
PVED-CL Controller for Electro-Hydraulic Steering, Version 1.38
Steering by Steering Wheel – Open Loop
Symbol Index Default
Yr 10y7 1000
Yl 10y8 -1000
Off 1y28 50
Cf 1y29 333
See chapters Mapping Steering Signals, Steering Actuator Sensor (feedback from vehicle wheels) and Steering Actuator Position to acquire "steering
actuator position".

Main Spool Dead-band Control Function

Symbol Index
Tolsout 116

Magnetic Valve Control

50 | © Danfoss | May 2016
Off This parameter sets the permitted actuation speed when hitting the end lock defined by Yr or Yl.
When the steering actuator passed Yr or Yl, actuation speed will decay to zero.
The default sets a speed that allows building up pressure when the actuator is located at Yr or Yl.
Value range
-1000 – 1000, Values smaller than 0 will be set equal to the positive equivalent
-1000 – 1000, Values greater than 0 will be set equal to the negative equivalent
0 to 1000 (0.0 - 100.0% of max port flow)
1 to 1000
Tolsout maximum time where the main spool is allowed to be operated proportionally within the valve
dead-bands. The main spool control range for this function can be seen on the
on page 50. This function is useful to eliminate frequent spool relocating events from its neutral to its
dead-band position and back (so called jumps) at low steering wheel speeds.
The flow request is 0 while moving the steering wheel within the defined steering wheel backlash range
(see Apply Backlash on page 40).

Dead-band Jump Control

Set Tolsout lower than 21 (ms) to momentarily set the main spool in neutral as soon as the flow request is
0, No proportional main spool movement will take place. The spool will jump from neutral to either of the
valve dead-bands depending on the flow request. The backlash parameter has no impact for these
Tolsout values.

Dead-band Hold and Proportional Control

Setting Tolsout between 21 and 30 000 (ms) defines the maximum time where the main spool is either
set on the valve dead-band or controlled proportionally within the dead-band (granted that the flow
request is 0 during this time).
After a flow request to either left or right port, the main spool will be set on the respective left or right
valve dead-band. Any steering wheel movement within the defined backlash region will result in
proportional main spool movement as a function of the steering wheel movement. Proportional control
will be allowed for Tolsout ms.
If the flow request has been 0 for Tolsout ms, the main spool will be set in neutral and any steering wheel
movements within the backlash range is ignored.
To utilize proportional control, a steering wheel backlash range needs to be created. If the backlash range
is set a low value, the main spool will effectively be operated as dead-band jump control.

Responding to Flow Requests after Tolsout

If the main spool has been set in neutral after Tolsout ms, any flow request will cause the spool to
immediately jump to the relevant spool position with no initial proportional dead-band control.
Default
10 000
Magnetic valves off delay time disables the magnetic valve bridge after a time specified in ms when the
flow request is 0, otherwise it remains enabled. This parameter is used when electrical energy
Value range
1 to 30 000 (ms)
11025583 | AQ00000216en-US0302
Dead-band Jump Control