Steering Device Transition; Threshold Definition; Define The Maximum Steering Motion Speed - Danfoss pved-cl Operation Manual

Operation Manual
PVED-CL Controller for Electro-Hydraulic Steering, Version 1.38

Steering Device Transition

Steering Device Transition

Threshold Definition

Define the Maximum Steering Motion Speed

Example: How the maximum signal change is carried out
Device
Steering by steering wheel
Steering by High priority steering device
Steering by Low priority steering device
Steering by High priority external set-point controller
36 | © Danfoss | May 2016
The PVED-CL allows steering with electric signals from more than one steering device. Every 50 ms, the
PVED sequentially monitors all mapped steering device signals according to their priority.
It selects one of steering devices based on:
•
the amount of signal change detected in the steering signal per time unit and
•
the current in System State
defined threshold, it is considered as a request to steer the vehicle with that particular steering
device.
The system state is used to ensure:
•
Smooth transition from one to another device by requiring the valve spool to be inside or near the
valve dead-band.
•
Reach-ability of the closed-loop control by demanding the steering actuator to be within the control
region of the closed-loop controller (if closed-loop control is applied).
•
Safe transition to a steering device, and hence program by only allowing this change at vehicle
speeds equal to or lower than the threshold value defined in
provided that a vehicle speed signal is present.
When all above criteria are fulfilled, the steering device is selected and the associated steering control
principle is applied. If no steering device fulfils the criteria the previous selected device remains. On
power up, all devices are normally in their rest position, which means that no device is selected. The
magnetic valve is disabled while no device is selected.
To determine if a steering device exceeds its defined threshold, two parameters shall be defined for each
applied steering device namely the maximum steering motion speed and the steering motion threshold.
The threshold is defined as a percentage of the maximum steering motion speed.
The fastest steering input is defined as the time in ms to change the input signal from its minimum to its
maximum value or visa versa, hence the value corresponding to 100%. This means e.g. the minimum time
required to make one full turn for the steering wheel, one full movement left to right on the joystick, etc.
CAN AD Volt
t2
900 4.5
4095
t1
0 100 0.5
Changes to parameters of non-present steering devices have no effect.
on page 19. When the steering signal change per time unit exceeds a user-
time
Index Default
111 500
311 200
411 200
511 200
Program Transition Control on page 19
Value range
500 – 750 (120 to 80 rpm)
150 – 450
150 – 450
10 – 2000
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