Steering by High Priority Steering Device – Closed Loop
EHPS Type 2 Automatic Steering Diagram
Q
Steering
cylinder
EHPS Valve
Automatic steering
OSP
PVE
Steering angle sensor
Position
sensor
P005 225E
Vehicle speed
Joystick or mini wheel
Steering
cylinder
EHPS valve
OSP
PVE
Q
High
priority
Functionality Tree
The tree below illustrates the functionality available in the PVED for steering by a potentiometer device
or by joystick or by mini wheel with speed output. The manufacturing default functionality is found by
following the red line. It can of course be modified by following the instructions in this chapter. The
switches in the tree are used to select the functionality required. In case different functionalities are
required, the EHPS software provides 5 programs from which the driver can select when the system is
fully operative. For steering by a device without spring return the PVED provides closed loop position
control. The steering signal is monotonic and represents the angle of the physical device. These devices
are normally friction held to prevent unintentionally steering due to machine vibrations. Use this mode
for implementation of proprietary auto-guidance applications i.e. auto-guidance applications that do not
conform to the ISO standardized auto-guidance messages. See
on page 94.
Open loop, fixed sensitivity, with fixed ramp
times
Related to
position of
steering
actuator
Sse = 2
Related to
vehicle speed
Sse=3
Open loop, fixed sensitivity, with no
ramps applied
Open loop, sensitivity related to steering actuator
position, with fixed ramp times
Open loop, sensitivity related to steering actuator
position, with no ramps applied
Open loop, sensitivity related to vehicle speed, with
fixed ramp times
Open loop, sensitivity related to vehicle speed,
with no ramps applied
Closed loop, Fixed sensitivity, no ramps possible
Closed loop
Cp=255
Fixed Sr=1
No Sr=0
Var Sr=2
C
on
tr
ol pr
inciple swit
ch
Sensitivit
y swit
ch
R
amp swit
ch
Open loop, fixed sensitivity, with ramp times
related to vehicle speed
Open loop, sensitivity related to steering actuator
position, with ramp times related to vehicle speed
Open loop, sensitivity related to vehicle speed, with
ramp times related to vehicle speed
Cp
Sse
Sr
Switches
No signal (0)
AD1 (1)
AD2 (2)
CAN (4)
C
hannel mapping swit
ch
Fixed
Sse=1
Open loop
Cp=0
default
P005 089E
Fixed Sr=1
No Sr=0
Var Sr=2
Fixed Sr=1
No Sr=0
Var Sr=2
*
* Sensitivity means: Port flow amplification
Y=0
1
2
3
4
Program number: Y
Tracking
For safety reasons, a tracking function ensures bump-less transition on control loop initialization. It forces
the user initially to operate the potentiometer knob into a position that matches zero deviation between
set point and current steering actuator position or by sweeping through it. While tracking, the
commanded port flow is limited at zero.
Operation Manual
PVED-CL Controller for Electro-Hydraulic Steering, Version 1.38
Steering by High Priority Steering Device – Closed Loop
72 |
©
Danfoss | May 2016
11025583 | AQ00000216en-US0302