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WLTP-DTP-LabProcICE-189. Introduction of SAE J2951 study - possibility of tighter tolerance for WLTP phase -. It is not ‘normalization’. But we would like to introduce it as one of the solution of less flexibility. SAE J2951 Index. Engine force
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WLTP-DTP-LabProcICE-189 Introduction of SAE J2951 study- possibility of tighter tolerance for WLTP phase - It is not ‘normalization’. But we would like to introduce it as one of the solution of less flexibility.
SAE J2951 Index • Engine force • FENG = [F0 + F1*V + F2*V2 + 1.015 * ETW * a]+ • Engine work increment • Wi = FENGi * di • Cycle energy (CE) • CE = ΣWi = Σ[(F0 + F1*Vi + F2*Vi2 + 1.015 * ETW * ai) * di]+ • Energy rating (ER) • ER = (CED - CET) / CET*100 • Distance rating (DR) • DR = (DD - DT) / DT*100 • Energy economy rating (EER) • EER = [1 – (DR / 100 +1) / (ER / 100 +1)] * 100 • Absolute speed change rating (ASCR) • ASCR = (ASCD - ASCT) / ASCT * 100 • ASC = ⊿t*Σ|ai| • Root mean squared speed error (RMSSE) • RMSSE = 2.237 * √(Σ(VDi - VTi)2) / N)
Points of evaluation J2951 Index can; • Detect too smooth driving within tolerance? • Detect it is due to vehicle performance or other intention? Evaluated data, • Data unable to follow the target due to vehicle performance. • Exclude the data with wide open throttle from above. • Data able to follow the target. Index RMSSE may be effective? • Need more data for practicability to achieve tighter tolerance.
Analysis of SAE J2951 Index by Validation data • Points of view • Detect the data unable to follow the target trace? • If exclude the data with WOT, the index become normal. (=similar as the data able to follow the target.) Unable to follow Unable to follow (Ex. WOT) Able to follow (MT) Able to follow (AT) Able to follow (AT) Detected ! DR also detected well, but distance can be adjusted easily. RMSSE works well. But analyzed by only 4 data… (Much) more data is necessary to evaluate practicability.
How to exclude the data with WOT? Black : Speed Red : Throttle Pedal angle These data are excluded from INDEX calculation. WOT Signal of throttle pedal angle or WOT is necessary.
Sensitivity of RMSSE (Ex-H) Exceeding tolerance Integration of (Vtarget -Vactual)2 If the data exceeding the tolerance is excluded, RMSSE≒0.596 RMSSE responds sensitively although the speed gap is within tolerance and short time period. It may be good INDEX for tighter tolerance. But more data analysis is necessary.