MDFAW 12.260 (Driver Requested Torque)

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See the funktionsrahmen for the following diagrams:

mdfaw-mdfaw MDFAW overview

mdfaw-pedchar Sub-function PEDCHAR: throttle pedal characteristic

mdfaw-mrfmx Sub-function MRFMX: maximum relative driver requested torque

mdfaw-dmlwhs Sub-function DMLWHS: indicated driver requested torque for change limitation in the homogenous charge mode

mdfaw-dmfabeg Sub-function DMFABEG: change limitation for the driver's requests

mdfaw-sawe Sub-function SAWE: change limitation during overrun fuel cut-off & reinstatement

mdfaw-filsawe Sub-function FILSAWE: filter for change limitation during overrun fuel cut-off & reinstatement

mdfaw-dashpot Sub-function DASHPOT: change limitation during negative load change (dashpot)

mdfaw-fildash Sub-function FILDASH: filter for dashpot

mdfaw-zdash Sub-function ZDASH: filter time constant for dashpot

mdfaw-ebdash Sub-function EBDASH: switching conditions for dashpot

mdfaw-mismeus Sub-function MISMEUS: change limitation during fast torque intervention for operating mode changeover

mdfaw-lsd Sub-function LSD: Change limitation during positive load changes (load change damping)

mdfaw-fillsd Sub-function FILLSD: filter for load change damping

mdfaw-zlsd Sub-function ZLSD: filter time constant for load change damping

mdfaw-pt2fil Sub-function PT2FIL: PT2-filter

mdfaw-eblsd Sub-function EBLSD: switching conditions for load change damping

mdfaw-mdbg Sub-function MDBG: torque change limitation

mdfaw-mifal Sub-function MIFAL: driver requested torque for the cylinder charge path

mdfaw-fwmifal Sub-function FWMIFAL: excessive increase factor for driver requested torque for the cylinder charge path during positive load changes

mdfaw-bits Sub-function BITS: Saving of the significant bits in the flag byte mdfaw_bits

MDFAW 12.260 Function Description

The duty of this function is to calculate the driver’s requested torque as a function of accelerator pedal position (wped_w) and cruise control output (mrfgr_w). Separate values are provided for cylinder charge and ignition influences (mifal_w, mifa_w).


The throttle pedal characteristic is defined by maps, where through pedal position and engine speed, a factor (relative torque) is stored to help scale indicated torque between the minimum and maximum. The relative driver’s requested torque can have values ​​greater than 100% (pedal crossover). For reverse gear, a separate map is available that can be used on vehicles with automatic transmission. To enhance driving comfort, a change in the driver’s requested torque limit can take place under certain conditions (load changes, overrun fuel cut-off and reinstatement, transition from part load to idle and vice versa. See sub-function DMFABEG).


The idle condition (B_ll) is set when the relative driver’s requested torque drops below the threshold MRFALLU and is reset when the threshold MRFALLO is exceeded. The cruise control condition (B_fgr) is set when the cruise controller output is greater than the output of the pedal characteristic. The integral component of the idle control (dmllri_w) is included in the driver’s request.


The change limitation for the driver’s requested torque (sub-function DMFABEG) is used to improve ride comfort and overrun fuel cut-off and smooth resumption of positive and negative load changes. With that, a DT1-element filtered torque loss (dmverl_w) is added behind the change limitation around jumps in the clutch torque to damp the connection or disconnection of load.

Overrun fuel cut-off/reinstatement


Via a PT1-filter, down-regulation of the target torques starting from the actual torque at zero takes place by overrun fuel cut-off; smooth resumption by up-regulation of the target torques starting from mizwmn_w to mimin_w. The filter time constants for up-regulation and down-regulation can be chosen independently of each other. One more time constant is made available for hard resumption and leaving idle (under light throttle). The initialization of the filters on the overrun fuel cut-off to the actual torque is needed to avoid a jump in torque on enabling of the ignition angle interventions. The filtering is, or is not cancelled:

- During active dashpot,

- For active load shock absorption,

- In the test laboratory

- On a steep negative speed gradient (uncoupling of thrust or throttle),

- When the clutch is actuated (configurable via CWDMFAB)

- mrfa gradient at higher threshold (important during hard resumption and when leaving the idle),

- Upon reaching the basic ignition angles.

Dashpot


The change limitation for negative load changes (dashpot) is implemented using a PT1-filter with gear and speed-dependent time constant. The PT1-filter runs at a negative gradient of the unfiltered driver’s requested torque. The dashpot is triggered when the difference between the filtered and unfiltered output value exceeds a clutch-dependent and torque-dependent threshold, and cruise control is not engaged. The trigger also always occurs at the transition to idle. The PT1-filter triggered by the dashpot is initialized with the actual torque in order to avoid a jump in torque during ignition angle interventions. The dashpot is terminated when the difference between filtered and unfiltered value falls below a gear-dependent threshold. As long as the dashpot is active, there will not be any overrun fuel cut-off (see function %BBSAWE).


The driver’s desired torque for the cylinder charge influence mifal_w is calculated by a dashpot with its own PT1-filter that is initialized when the unfiltered driver’s desired torque drops below the trigger level. In this way, a steep initial drop is reached, which leads to the rapid closing of the throttle. Then a soft change is made to the target value. The dashpot can be active only when:

- The general dashpot-enable is done viaCWDMFAB Bit1,

- There is no commitment to overrun fuel cut-off,

- Load shock absorption is not active,

- There is the speed signal,

- The minimum speed is exceeded for dashpot,

- The clutch is not pressed,

- Start end is reached,

- The response is greater than zero,

- ASR intervention is not active,

- The cylinder charge is greater than the minimum charge.

Load Shock Absorption


The change limitation during positive load changes is realized with the help of a PT2 filter whose damping and time constant are gear- and speed-dependent. The PT2 filter runs with a positive gradient of the unfiltered driver’s requested torque. Load shock damping is triggered when the difference between unfiltered and filtered output value exceeds a gear- and clutch torque-dependent threshold. The PT2 filter is triggered when the load shock absorption is initialized with the actual torque or a speed-and gear-dependent initial value, to avoid a jump in torque upon enabling of the ignition angle interventions and to influence the response behavior. The load shock damping is terminated when the difference between the filtered and unfiltered value drops below a gear-dependent threshold.


The driver’s desired torque for the cylinder charge influence mifal_w with active load shock damping is calculated from a map which depends on the desired torque for the ignition influence (mifa_w) and on the gear, which is a limitation on the unfiltered target. Thus, the cylinder charge can be controlled so that there is no significant ignition angle intervention in order to set the desired torque curve.


The load shock damping can be active only when

- Load shock damping is generally enabled via CWDMFAB Bit 0,

- There is no idle

- For vehicles with CVT transmission, the torque gradient limitation is not active and the torque converter clutch is not open,

- The speed signal is present

- The minimum speed for load shock absorption is exceeded,

- The clutch is not actuated

- Cruise control is not engaged,

- Speed ​​and speed limits are not active,

- End of start conditions is reached,

- The gear is greater than zero,

- No traction control intervention is active.


The PT2 filter is implemented with two integrators and feedback. There is also the possibility that the filter is initialized with a given value (iwflsd_w) if the condition B_iflsd is set.

MDFAW 12.260 Application Notes


CWDMFAB


Bit 0 0: Load shock damping deactivated

1: Load shock damping enabled

Bit 1 0: Dashpot deactivated

1: Dashpot enabled

Bit 2 0: Load shock damping with B_gwhs inactive

1: Load shock damping with B_kupplv inactive

Bit 3 0: Dashpot with B_gwhs inactive

1: Dashpot with B_kupplv inactive

Bit 4 0: Overrun fuel cut-off/reinstatement filter with B_kuppl active

1: Overrun fuel cut-off/reinstatement filter with B_kuppl inactive

Bit 5 0: Dashpot and load shock damping even with traction control intervention enabled

1: Dashpot and load shock damping with traction control intervention inactive

Bit 6 0: Dashpot triggering independently of B_ll

1: Dashpot triggering on positive edge of B_ll

Bit 7 0: Load shock damping and dashpot triggering via threshold inactive, until cruise control intervention

1: Load shock damping and dashpot triggering via threshold also possible during cruise control intervention

CWMDFAW

Bit 0 0: Initialization of migef_w when reinstating with miistoar_w

1: Initialization of migef_w when reinstating with 0 (for sequential reinstatement)

Bit 1 0: Initialization of mifal_w with dashpot with mivbeb_w

1: Initialization of mifal_w with dashpot with mibdp_w - dmdpo_w

Bit 2 0: Load shock damping with B_kupplv or B_gwhs inactive

1: Enable the load and shock damping independent of B_kupplv and B_gwhs

KFPEDL and KFPEDR must contain smaller values than KFPED at the same pedal value and the same speed so that the torque monitoring only depends on KFPED.

Parameter

Description

CWDMFAB

Codeword ECU switch for change limitation

CWMDFAW

Codeword for %MDFAW

DMDPOSCH

Delta torque dashpot triggering in the shift operation

DMDPUG

Delta torque dashpot end

DMIFLSD

Delta torque for initialising filter load shock damping

DMISMEUS

Delta indicated torque for change limitation by B_mismeus

DMLSDUG

Delta torque end load shock damping

DMRFAWEN

Threshold mrfa-gradient for deactivating PT1-filter during reinstatement

DRLMINDP

Offset on rlmin for switching off dashpot

FGMIFAL

Weighting factor for elevation via KFWMIFAL

FGZLSD

Weighting for reduction via KFZLSD

FKFPEDV

Factor for interpolation between the two pedal maps

FKZDPTM

Correction factor time constant dashpot

FLRMIFAL

Factor for driver requested torque cylinder charge path in low range

FLRZDASH

Factor for dashpot time constant im low range

FLRZLSD

Factor for load shock damping-time constant in low range

FZDA1SCH

Dashpot time constant correction factor in shift operation

FZDA2SCH

Dashpot time constant correction factor at small clutch torque in shifting operation

KFDLSD

Damping PT2-filter load shock damping

KFDMDPO

Delta torque dashpot triggering

KFDMLSDO

Delta torque triggering load shock damping

KFDMLSDS

Delta torque triggering load shock damping after shifting operation

KFMIFABG

Delta torque for gradient limitation

KFMIFALS

Indicated driver requested torque for cylinder charge path during load shock damping

KFMILSD

Indicated torque initial value for load shock damping

KFPED

Relative driver requested torque from throttle pedal

KFPEDL

Relative driver requested torque at low speeds

KFPEDR

Relative driver requested torque from throttle pedal for reverse gear

KFWMIFAL

Excessive increase factor for cylinder charge path during load shock damping

KFWZLSD

Reduction factor for time constant load shock damping

KFZDASH

Time constant PT1-filter dashpot

KFZDASH2

Time constant PT1-filter dashpot at small clutch torque

KFZLSD

Time constant PT2-filter load shock damping

MDIMX

Maximum indicated engine torque

MIFABGMX

Maximum value mifa_w for torque change limitation

MIFALMF

Indicated driver requested torque for cylinder charge path with active gradient limitation

MKFADPN

Clutch torque for changeover of dashpot-filter time

MKFADPN1

Clutch torque for changeover of dashpot-filter time for air conditioning

MKMIFABG

Clutch torque for activating the torque change limitation

MRFALLO

Upper idle threshold of the relative driver requested torques

MRFALLU

Lower idle threshold of the relative driver requested torques

MRFAVLN

Full load detection threshold for the relative driver requests

NGFSAWE

Threshold speed gradient for overrun fuel cut-off/reinstatement filter

SNM12MDUW

Sample point distribution for engine speed

SWP16MDUW

Sample point distribution for throttle pedal angle

SY_ASG

System constant: automated manual transmission present

SY_BDE

System constant: petrol direct injection

SY_CVT

System constant: continuously variably transmission present

TDMFBSA

Time constant PT1-filter during overrun fuel cut-off

TDMFBWE

Time constant PT1-filter during smooth reinstatement

TDMFNSG

Filter time constant during target speed increase (continuously variably transmission)

TDMFWEMI

Filter time constant during hard reinstatement

TDMLSDS

Time after clutch actuation with modified load shock damping trigger

TVFSAWE

Delay time for resetting B_fil

VDASH

Minimum speed for dashpot

VLSD

Minimum speed for load shock damping

Variable

Description

B_CVT

Condition: continuously variable transmission

B_DASH

Condition: dashpot change limitation active

B_DASHV

Condition: dashpot delay

B_DP

Condition: dashpot value greater than driver request (= 1)

B_EDP

Condition: dashpot permission

B_ELSD

Condition: load shock damping permission

B_FAAN

Condition: functional requirement: general speed increase

B_FGR

Condition: cruise control (Tempomat) active

B_FIL

Condition: PT1-filter for overrun fuel cut-off/reinstatement active

B_GWHS

Condition: gear change by manual switch

B_IFLSD

Condition: initialising filter load shock damping

B_KO

Condition: compressor enabled

B KUPPL

Condition: clutch actuated

B_KUPPLV

Condition: delayed clutch actuation

B_LL

Condition: idle

B_LLVFGR

Condition: idle forbidden by vehicle speed limiter

B_LOWRA

Condition: Intermediate clutch for low range switch-off

B_LS

Condition: load shock limitation without driver request (=1)

B_LSD

Condition: positive load shock damping active

B_MGBGAKT

Condition: torque gradient limitation active

B_MGBGET

Condition: torque gradient limitation active

B_MIFABG

Condition: mifa limitation

B_MISMEUS

Condition: torque change limitation by B_smeus

B MRPEDASG

Condition: changeover driver requested torque from AMS

B_MRPFA

Condition: zeroing of mrped_w because of general speed increase

B_NMAX

Condition: speed limiter active

B_NMOT

Condition: engine speed: n > NMIN

B_NSGET

Condition: torque requirement for CVT: position the pulley cone

B_SA

Condition: overrun fuel cut-off

B_SAB

Condition: overrun fuel cut-off standby

B_SABFG

Condition: overrun fuel cut-off standby or enable

B_STEND

Condition: end of start conditions reached

B_TDMLSDS

Condition: time after clutch actuation with modified load shock damping trigger

B_TMISMEUS

Condition: trigger for torque filtering B_mismeus

B VL

Condition: full load

B_VMAX

Condition: speed limiter active

B_VNULL

Condition: vehicle stopped

B_WKAUF

Condition: torque converter open

B_ZWSCH

Condition: ignition angle for stratified charge mode active

DLSD_W

Damping PT2-filter in load shock damping

DMBEBL_W

Delta torque for triggering load shock damping

DMDPO_W

Delta torque dashpot triggering

DMDPU_W

Delta torque dashpot end

DMGBEG_W

Delta torque for gradient limitation

DMLLRI_W

Required torque change from idle control (integral component)

DMLSDO_W

Delta torque on triggering load shock damping

DMLSDU_W

Delta torque at end of load shock damping

DMLWHS_W

Delta torque during load alternation between homogeneous and stratified charge modes

DMRFAWE_W

Threshold mrfa-gradient for deactivating PT1-Filter during reinstatement

DMVERL_W

Torque loss after DT1-Filter

FKFPED

Factor for interpolation between the two pedal maps

FWMIFAL

Excessive increase factor in cylinder charge path load shock damping

FWZLSD

Reduction factor time constant load shock damping

FZDASH

Factor time constant dashpot

GANGI

Actual gear

IWFLSD_W

Initialising value for filter load shock damping

MDFAW_BITS

Flag byte for %MDFAW

MDGRAD_W

Torque gradient limiting through the transmission

MDSLWHOM_W

Load alternation torque loss in the homogeneous mode

MDSLW_W

Torque loss: load alternation

MDVERL W

Engine torque loss

MIASRS_W

Indicated target engine torque traction control for fast intervention

MIBAS_W

Indicated basic torque

MIBDP_W

Indicated target engine torque dashpot

MIBLSD_W

Limited indicated torque for load shock damping

MIFA

Indicated driver requested engine torque

MIFABG_W

Gradient-limited driver requested torque

MIFAL_W

Indicated driver requested torque for torque coordination on the charge path

MIFA_W

Indicated driver requested engine torque

MIGEF_W

Gefiltertes indicated driver requested torque

MIISTOAR_W

Actual torque without anti-judder component

MIMAX_W

Maximum permissible indicated torque

MIMINHOM_W

Minimum torque for the homogeneous charge mode

MIMIN_W

Minimum engine torque

MINBEG_W

Indicated driver requested torque after / change limitation

MISMEUS_W

Indicated torque during change limitation B_mismeus

MIVBEB_W

Indicated torque before change limitation, upper limit of mimax_w

MIVBEGVH_W

Indicated driver requested torque before maximum limit for homogeneous charge mode

MIVBEGV_W

Indicated driver requested torque before maximum limit

MIVBEG_W

Indicated driver requested torque before change limitation

MIZWMN_W

Indicateed engine torque at the latest igniton angle

MKFADPN_W

Clutch torque for changeover dashpot-filter time

MKFANB_W

Clutch torque from limited driver’s request

MKFA_W

Driver requested torque (clutch) after change limitation

MRFAMXAS W

Relative driver requested torque maximum value from automated manual transmission

MRFAMX_W

Relative driver requested torque maximum value

MRFA_W

Relative driver requested torque from cruise control and throttle pedal

MRFGR_W

Relative torque requirement from cruise control

MRPEDASG W

Relative driver requested torque from automated manual transmission

MRPEDL_W

Relative driver requested torque from the throttle pedal for less speed

MRPEDS W

Relative driver requested torque from the throttle pedal for greater speed

MRPED_W

Relative driver requested torque

NGFIL_W

Filtered speed gradient

NMOT W

Engine speed

RLMINDP_W

Minimum relative cylinder charge for dashpot switch off

RLMIN_W

Minimum permitted relative load

RL_W

Relative air charge (word)

TMOT

Engine coolant temperature

VFZG

Vehicle speed

WPED_W

Normalised throttle pedal angle

ZDASH1_W

Time constant PT1-filter dashpot

ZDASH2_W

Time constant PT1-filter dashpot at small clutch torque

ZDASH_W

Time constant dashpot

ZLSDV_W

Time constant PT2-filter load shock damping before reduction

ZLSD_W

Time constant PT2-filter load shock damping

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