View source for ARMD 10.40 (Torque-Based Anti-Jerk Function)

See the ''funktionsrahmen'' for the following diagrams:

armd-armd Main function

armd-kifz Subfunction KIFZ (amplification of vehicle model)

armd-flrar Subfunction FLRAR (amplification factor for modelling of external load)

armd-fdar Subfunction FDAR (amplification factor for anti-jerk intervention)

armd-nmoti Subfunction NMOTI

armd-ndfil Subfunction NDFIL (filtered engine speed difference)

armd-frgar Subfunction FRGAR

armd-iniarv Subfunction INIARV

armd-kup gw Subfunction KUPGW

armd-dmar Subfunction DMAR (delta torque anti-jerk)

armd-varss Subfunction VARSS


<u>ARMD 10.40 Function Description</u>

<u>Function purpose</u>

The anti-jerk function detects oscillations of the power train and damps them out by applying opposing-phase torque interventions. The torque intervention is converted into an ignition angle offset by the torque interface.


<u>Desired phase position of the torque intervention</u>

In order to damp the power train oscillation efficiently, the torque intervention should counteract engine speed oscillations. Thereby the same effect is achieved as if the attenuation coefficient of the drive shaft is increased.


<u>Operation pattern of anti-jerk function</u>

Basic idea: a reference speed without oscillation and corresponding to the driver’s demand is evaluated. The difference between desired and actual engine speed isolates the oscillation. A counteracting delta torque is set which is proportional to this oscillation.

The function is realized by a simple vehicle model consisting of an integrator with the constant kifz_w. The input to this integrator is the difference between the driver’s predetermined clutch torque mkar_w and the load torque mlast_w. The output from the integtrator is the modelled engine speed nmod_w. The engine speed difference ndiff_w between the modelled engine speed nmod_w and the actual engine speed nmot_w now forms the basis for the torque intervention as well as for the calculation of the load torque. The load torque is evaluated proportional to the engine speed difference and the factor flrar is taken from the corresponding characteristic line. The engine speed difference ndiff_w contains another offset besides the oscillation part.
This offset is filtered on a 50 ms scan timescale through a discrete second order low pass filter. (Coefficients of the nominator polynomial are denoted A0, A1 and A2 and of the denominator polynomial 1, B1 and B2.


The filtered offset ndfil_w is substracted from the differential engine speed and gives the engine speed oscillation ndar_w.
Proportionally to this engine speed and using the factor fdar, a delta torque as a torque intervention is calculated. If this intervention lays between the limits KFDMDARU and KFDMDARO, it is set to zero.


<u>Activation Conditions</u>

The model is always active, just the intervention can be switched off.


<u>Application Notes</u>

<u>Conditions for calibration of anti-jerk</u>

The basic calibration of the vehicle must have been done. This includes the transition compensation and all functions for the torque interface.


1. Evaluation of the integrator constant kifz_w and flrar

Coarse application:

Drive on the road (flat surface, no hills) at a constant speed in respective gear with the anti-jerk function deactivated (fdar=0).
Then execute a change in load and register the calculated coupling torque mkar_w and the engine speed nmot_w.

Evaluation of integrator constant as follows: at a load step the torque jump is approximately delta M (in %) and the speed approximately rises with constant gradient gradn (in RPM/s). Kifz_w is then calculated from the expression gradn/(delta M). A typical value for second gear is 4.6 x 100/MDNORM [RPM/(sx%)].


Fine application:

Driving on flat surface. Set the product kifz_w x flrar to a fixed value (recommendation: 15). Realization of load jumps with registration of mkar_w, mlast_w, nmot_w and ndiff_w. Vary the couple kifz_w and flrar (maintaining the product constant!) until ndiff_w remains approximately constant during a load jump.

In principle the following process is valid for the amplification factor flrar: high factors cause a reduction of the offset ndfil_w, but also a big phase advance of ndiff_w.


2. Evaluation of filter parameters

Low pass filter in 50 ms scan rate: transmission function has the form G(z) = Z(z)/N(z) with

Z(z) = A0 + A1z<sup>-1</sup> + A2z<sup>-2</sup>
N(z) = 1 + B1z<sup>-1</sup> + B2z<sup>-2</sup>.

Select one of the low pass filters listed in the table below, according to the appearing jerk frequency:

{| border="1"
|-
| 
TP No.
| 
Limit freq.
| 
A0
| 
A1
| 
A2
| 
B1
| 
B2
|-
| 
1
| 
0.67 Hz
| 
0.0095
| 
0.0191
| 
0.0095
| 
-1.7056
| 
0.7437
|-
| 
2
| 
0.80 Hz
| 
0.0134
| 
0.0267
| 
0.0134
| 
-1.6475
| 
0.7009
|-
| 
3
| 
1.00 Hz
| 
0.0201
| 
0.0402
| 
0.0201
| 
-1.5610
| 
0.6414
|}


Low pass filter No. 3 is recommended. The attenuation of the jerk frequency is determined by the margin between the jerk frequency and the filter cut-off frequency. The bigger the filter cut-off frequency, the smaller the time the filter needs to stabilize. Attenuation: modification of a single coefficient of G(z) is not permitted!


3. Evaluation of fdar

Recommendation is fdar = 0.67 x 100/MDNORM (%/RPM). Increase of attenuation by enlargement of fdar, reduction of fdar decreases the attenuation.


4. Thresholds KFDMDARO and KFDMDARU

In case the delta torque for the intervention is within these thresholds, it is set to zero. This avoids undesired ignition angle instability. Typical values are: KFDMDARU = -5 x 100/MDNORM [%], KFDMDARO = 5 x 100/MDNORM [%].


<u>Abbreviations</u>

{| border="1"
|-
| 
A0
| 
Transmission
coefficient
|-
| 
A1
| 
Transmission
coefficient
|-
| 
A2
| 
Transmission
coefficient
|-
| 
B1
| 
Transmission
coefficient
|-
| 
B2
| 
Transmission
coefficient
|-
| 
CWARMD
| 
Code
word anti jerk function
|-
| 
DMARMX
| 
Maximum
limit of the steady-state torque interventions of the anti-jerk function
|-
| 
DNFILO
| 
Upper
threshold of filter output gradient ndfil
|-
| 
DVFZAR
| 
Hysteresis
for vehicle speed limit during anti-jerk
|-
| 
FLRAWG
| 
Integrator
gain factor of the load controller during AT (throttle plate closed)
|-
| 
FLRHG
| 
Integrator
gain factor of the load controller
|-
| 
FRARAWG
| 
Integrator
gain factor during AT (throttle plate closed)
|-
| 
FRARHG
| 
Integrator
gain factor
|-
| 
KFDMDADP
| 
Upper
threshold for torque-intervention during dashpot
|-
| 
KFDMDARO
| 
Upper
threshold for torque intervention
|-
| 
KFDMDAROS
| 
Upper
threshold for steady-state torque intervention
|-
| 
KIFZGAWG
| 
Integrator
gain factor in the vehicle model with AT (throttle plate closed)
|-
| 
KIFZGHG
| 
Integrator
gain factor in the vehicle model with HG
|-
| 
NARAO
| 
Upper
engine speed threshold for anti-jerk function active
|-
| 
NARASTG
| 
RPM
threshold in higher gear for anti-jerk active
|-
| 
NARLLGA
| 
Speed
threshold for anti-jerk at idle
|-
| 
NDFILOG
| 
Threshold
for filter output ndfil
|-
| 
NDIFFOG
| 
Threshold
engine speed difference for initialization of anti-jerk during braking
|-
| 
NVG
| 
Factor
to calculate engine speed initialization
|-
| 
NVMNG
| 
Minimum
speed / velocity ratio
|-
| 
NVMXG
| 
Maximum
speed / velocity ratio
|-
| 
SMK08MDSW
| 
Anti-jerk
torque dependent basic point (number =8)
|-
| 
TAREIN
| 
Blocking
time for anti-jerk function
|-
| 
TMAR
| 
Lower
engine temperature threshold for anti-jerk release
|-
| 
TMLAST
| 
Blocking
time until the initialization of the anti-jerk is triggered at deceleration
|-
| 
TVARS
| 
Delay
time until anti-jerk is inactive again
|-
| 
TVARSS
| 
Delay
time for anti-jerk becoming inactive again in steady-state conditions
|-
| 
TVKUPAR
| 
Delay
time for clutch for anti-jerk function
|-
| 
TVKUPHS
| 
Delay
time for clutch switch during shifting in higher gear
|-
| 
TVKUPRS
| 
Delay
time for clutch switch during shifting in lower gear
|-
| 
TZSPINI
| 
Blocking
time for filter initialisation
|-
| 
VARAU
| 
Minimum
vehicle speed for anti-jerk active
|-
| 
WPEDU
| 
Pedal
lower threshold value for anti-jerk function
|-
| 
B_AR
| 
Condition:
anti-jerk active
|-
| 
B_ARGF
| 
Condition:
anti-jerk transition window
|-
| 
B_AUTGET
| 
Condition:
automatic gearbox
|-
| 
B_BREMS
| 
Condition:
brake operated
|-
| 
B_DASHV
| 
Condition:
dashpot delayed
|-
| 
B_FGR
| 
Condition:
driver's set engine torque determined by cruise control
|-
| 
B_GFEN
| 
Condition:
transition window
|-
| 
B_GWHS
| 
Condition:
gear change on manual transmission vehicle
|-
| 
B_HPNMOT
| 
Condition:
high-point speed oscillation
|-
| 
B_INIAR
| 
Condition:
initialization of anti-jerk function
|-
| 
B_INIAR1
| 
Condition:
provisional initialization of anti-jerk function
|-
| 
B_INIARV
| 
Condition:
initialization of the filter function is delayed
|-
| 
B_KUPGW
| 
Condition:
clutch applied until shifting of geanti-jerk is detected
|-
| 
B_KUPPL
| 
EGAS
Condition: clutch is disengaged
|-
| 
B_LL
| 
Condition:
idle
|-
| 
B_LSD
| 
Condition:
limitation of positive torque gradient active
|-
| 
B_SA
| 
Condition:
fuel cut-off
|-
| 
B_STEND
| 
Condition:
end of start reached
|-
| 
B_TPNMOT
| 
Condition:
low-point speed oscillation
|-
| 
B_TVARS
| 
Condition:
anti-jerking function dynamically active
|-
| 
B_TVARSS
| 
Condition:
anti-jerking function steady-state active
|-
| 
B_WK
| 
Condition:
converter lockup clutch closed
|-
| 
DMAR_W
| 
Delta
torque anti-jerk
|-
| 
FDAR
| 
Amplification
factor for anti-jerk intervention
|-
| 
FLRAR
| 
Amplification
factor for modelling of external load
|-
| 
GANGI
| 
Engaged
gear
|-
| 
KIFZ_W
| 
Amplification
of vehicle model
|-
| 
MDBES_W
| 
Acceleration
torque
|-
| 
MDVERL_W
| 
Resistant
torque of the engine
|-
| 
MIFA_W
| 
Desired
indicated engine torque
|-
| 
MISOLV_W
| 
Indicated
resultant nominal torque before torque limitation
|-
| 
MKAR_W
| 
Calculated
clutch torque for anti-jerk function
|-
| 
MLAST_W
| 
Estimated
load moment
|-
| 
NDAR_W
| 
RPM
difference for torque control
|-
| 
NDFIL_W
| 
Filtered
engine speed difference
|-
| 
NDIFFOG_W
| 
Threshold
engine speed difference for reset of anti-jerk during braking
|-
| 
NDIFF_W
| 
Engine
speed difference for ISC amplification
|-
| 
NMODIV_W
| 
Engine
speed for initialising ARMD calculated from velocity
|-
| 
NMOD_W
| 
Engine
speed from model
|-
| 
NMOT_W
| 
Actual
engine speed
|-
| 
NVQUOT_W
| 
Quotient
engine speed / vehicle speed
|-
| 
TMOT
| 
Engine
temperature
|-
| 
VFZG
| 
Vehicle
speed (km/h)
|-
| 
VFZG_W
| 
Vehicle
speed (km/h, word)
|-
| 
WPED_W
| 
Normalised
throttle pedal angle (word)
|}