Verification Of Auto-Calibration Result Stability; Verification Of The Open-Loop Performance; Verification Of The Closed-Loop Performance; Logging And Monitoring - Danfoss pved-cl Operation Manual

Operation Manual
PVED-CL Controller for Electro-Hydraulic Steering, Version 1.38
Installation
30 | © Danfoss | May 2016

Verification of auto-calibration result stability

Check that the calibration results can be reproduced repeatedly (10-20 times) for a specific set of auto-
calibration command values. The resulting parameters Xspr_0 and Xspl_0 should stay within
±XspIncrementSize.
If repeatability is poor, then adjust the auto-calibration command values. Typically, YactDiffThreshold and
XspCalibrationOffset are subject for tuning and needs to be increased.

Verification of the open-loop performance

Check that no unwanted steering actuator movement takes place while operating the PVED-CL in open-
loop mode for e.g. variable steering ratio or joystick applications. Verify that the steering actuator is not
quivering in a steady state and that the steered wheels are not moving aggressively for small steering
wheel or joystick inputs. Both situations indicate no or a too small hydraulic dead-band.
XspCalibrationOffset should be increased and auto-calibration is repeated.
Secondly, verify that the steering performance is symmetric in both directions i.e. that the steering
actuator moves with the same speed in both directions for the same steering input in both directions.
If asymmetry is evident then a new valve auto-calibration shall be performed.

Verification of the closed-loop performance

Check that the desired steering accuracy can be obtained when using the PVED-CL in closed-loop mode
such as auto-steering. The vehicle shall follow the path within the expected precision with small steering
actuator movements.
If the vehicle cannot follow a path within the expected precision or deviates from the desired path, then
it may be due to a hydraulic dead-band. Increase ClosedLoopXspOffset in steps of 5-10 and test until the
performance is satisfactory.
If the steered wheels move aggressively and jerky while following a path in closed-loop mode, then the
valve outputs too much flow for small corrections and ClosedLoopXspOffset shall be decreased and
tested in steps of 5-10.
If there is a tendency that the vehicle deviates in only one direction in closed-loop mode, then one of the
open-loop dead-bands may not be correct and a new valve auto-calibration shall be performed.

Logging and monitoring

In addition to ValveAutoCalibrationStatus, PVED-CL status set 1 can also be enabled for detailed
monitoring and logging of the CAN bus traffic while the auto-calibration runs.
The below chart below shows the auto-calibration progress of an EH valve with a static main spool, fitted
to a 150 HP tractor. Values from
XspStartSearch 50, XspIncrementSize 5, YactDiffThreshold 20 and TimeOutPeriod 500.
Suggested valve auto-calibration command values on page 29 are used;
11025583 | AQ00000216en-US0302