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CO2MPAS Changes
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.. _begin-changes:

v1.0.1: 1-Oct 2015, 2nd release
===============================
- Comprehensive modeling with multiple alternative routes depending on
  available data.
- Tested against a sample of 1800 artificially generated vehicles (simulations).
- The model is currently optimized to calculate directly the NEDC CO2 emissions.

Known Limitations
-----------------

#. When data from both WLTP H & L cycles are provided, the model results in
   average NEDC error of ~0.3gCO2/km +- 5.5g/km (stdev) over the 1800 cases
   available to the JRC. Currently no significant systematic errors are observed
   for UDC and EUDC cycles.  No apparent correlations to specific engine or
   vehicle characteristics have been observed in the present release.
   Additional effort is necessary in order to improve the stability of the tool
   and reduce the standard deviation of the error.
#. It has been observed that CO2MPAS tends to underestimate the power requirements
   due to accelerations in WLTP.
   More feedback is needed from real test cases.
#. The current gearbox thermal model overestimates the warm up rate of the gearbox.
   The bug is identified and will be fixed in future versions.
#. Simulation runs may under certain circumstances produce different families
   of solutions for the same inputs
   (i.e. for the CO2 it is in the max range of 0.5 g/km).
   The bug is identified and will be fixed in future versions.
#. The calculations are sensitive to the input data provided, and in particular
   the time-series. Time series should originate from measurements/simulations
   that correspond to specific tests from which the input data were derived.
   Mixing time series from different vehicles, tests or cycles may produce
   results that lay outside the expected error band.
#. Heavily quantized velocity time-series may affect the accuracy of the
   results.
#. Ill-formatted input data may NOT produce warnings.
   Should you find a case where a warning should have been raised, we kindly
   ask you to communicate the finding to the developers.
#. Misspelled input-data which are not compulsory, are SILENTLY ignored, and
   the calculations proceed with alternative routes or default-values.
   Check that all your input-data are also contained in the output data
   (calibration files).
#. The A/T module has NOT been tested by the JRC due to the lack of respective
   test-data.
#. The A/T module should be further optimized with respect to the gear-shifting
   method applied for the simulations. An additional error of 0.5-1.5g/km  in
   the NEDC prediction is expected under the current configuration based
   on previous indications.
#. The model lacks a torque-converter / clutch module. JRC requested additional
   feedback on the necessity of such modules.
#. The electric systems module has not been tested with real test data.
   Cruise time series result in quantized squared-shaped signals which are,
   in general, different from analog currents recorded in real tests.
   More test cases are necessary.
#. Currently the electric system module requires input regarding both
   alternator current and battery current in  order to operate. Battery current
   vector can be set to zero but this may reduce the accuracy of the tool.
#. The preconditioning cycle and the respective functions has not been tested
   due to lack of corresponding data.


v0: Aug 2015, 1st unofficial release
====================================
Bugs reported from v0 with their status up to date:

#. 1s before acceleration "press clutch" not applied in WLTP:
   **not fixed**, lacking clutch module, problem not clear in Cruise time series,
   under investigation
#. Strange engine speed increase before and after standstill:
   **partly corrected**, lack of clutch, need further feedback on issue
#. Upshifting seems to be too early, also observed in WLTP, probably
   gearshift point is not "in the middle" of shifting:
   **not fixed**, will be revisited in future versions after comparing with
   cruise results
#. RPM peaks after stop don't match the real ones:
   **pending**, cannot correct based on Cruise inputs
#. Although temperature profile is simulated quite good, the consumption between
   urban and extra-urban part of NEDC is completely wrong:
   **problem partly fixed**, further optimization in UDC CO2 prediction
   will be attempted for future versions.
#. Delta-RCB is not simulated correctly due to a too high recuperation energy
   and wrong application down to standstill:
   **fixed**, the present release has a completely new module for
   calculating electric systems. Battery currents are necessary.
#. Output of more signals for analysis would be necessary:
   **fixed**, additional signals are added to the output file.
   Additional signals could be made available if necessary (which ones?)
#. Check whether a mechanical load (pumps, alternator and climate offset losses)
   as torque-input at the crankshaft is applied:
   **pending**, mechanical loads to be reviewed in future versions after more
   feedback is received.
#. Missing chassis dyno setting for warm-up delta correction:
   **unclear** how this should be treated (as a correction inside the tool or
   as a correction in the input data)
#. SOC Simulation: the simulation without the SOC input is much too optimistic
   in terms of recuperation / providing the SOC signals does not work as
   intended with the current version:
   **fixed**, please review new module for electrics.
#. The gearshift module 0.5.5 miscalculates gearshifts:
   **partially fixed**, the module is now included in CO2MPAS v1 but due to lack in test cases
   has not been further optimized.
#. Overestimation of engine-power in comparison to measurements:
   **indeterminate**, in fact this problem is vehicle specific. In the test-cases
   provided to the JRC both higher and lower power demands are experienced.
   Small deviations are expected to have a limited effect on the final calculation.
   What remains open is the amount of power demand over WLTP transient phases
   which so far appears to be systematically underestimated in the test cases
   available to the JRC.
#. Overestimation of fuel-consumption during cold start:
   **partially fixed**, cold start over UDC has been improved since V0.
#. CO2MPAS has a pronounced fuel cut-off resulting in zero fuel consumption
   during over-runs:
   **fixed**, indeed there was a bug in the cut-off operation associated to
   the amount of power flowing back to the engine while braking.
   A limiting function is now applied. Residual fuel consumption is foreseen
   for relatively low negative engine power demands (engine power> -2kW)
#. A 5 second start-stop anticipation should not occur in the case of A/T
   vehicles: **fixed**.
