Applicability of Driving Index WLTP-06-16e Study on Applicability of Driving Index (defined in SAE J2951) to WLTC

< Background > It is quite reasonable to have tolerance for each set point under the emission/fuel consumption test procedure from the view points of testing practicability. On the other hands, the tolerance have a possibility to create test result variations. These variations may cause inappropriate information to customer and/or unfair competitions. WLTP has been trying to narrow the tolerance and to stringent the test procedure, however, it still has a room for data variations. European commission has been reviewing all possible flexibilities in the WLTP gtr and their studies are under going with support of TNO and TUG. Japan focus on driving tracability as one of the most significant factors since new test cycle profile has changed to micro-transient mode from trapezium mode.

Trace technique ： Normal (keep the target trace as much as possible), < Overall Test Plan > Test vehicles： Trace technique ： Normal (keep the target trace as much as possible), Smoothing, Rough, Rough-2 (see below) # of Tests ： Vehicle A：1.3L, Gasoline, CVT, have few difficulty to follow the trace Vehicle B：0.66L, Gasoline, CVT, have difficulty to follow the trace  study how to treat WOT driving portions Vehicle C：2.0L, Gasoline, 6MT  study how to treat gear shift portions Vehicle condition Normal-1 Smooth Rough-1 Rough-2 (Slightly) Cold 1 - Hot 2 Smoothing Rough higher than target lower than target Smooth acceleration Rough pedal operation

< Conclusion > It was observed that drive trace indexes are able to detect the unexpected driving technique (smooth or rough) and to eliminate the inappropriate cycle trace by applying the appropriate criteria. (ASCR and RMSSE are possible candidate indexes, on the other hands, ER, DR and EER have weakness due to offset of positive and negative side) It was observed that special treatment during wide-open-throttle operation is necessary. More study on how to treat gear shift events is required. It was observed that negative side (smooth driving) drive trace index has slight correlation with FC value, on the other hands, positive side (rough driving) has no correlation with FC value.

< Request to all CPs > Evaluate the drive trace index (provide calculation tool, if necessary). Speed sampling rate : 10Hz (  need to modify gtr description). < Next Actions > Provide specific procedure for WOT operation and gear shift events. Propose driving index criteria for test validity. Collaborate “normalization procedure” with TUG.

Driving Indexes defined in SAE J2951 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 Combined ER and DR Absolute speed change rating (ASCR) ASCR = (ASCD - ASCT) / ASCT * 100 ASC = ⊿t*Σ|ai| Integrate the acceleration (= speed fluctuation) Root mean squared speed error (RMSSE) RMSSE = √(Σ(VDi - VTi)2) / N) Integrate the difference between target speed and actual speed

Test results-1 (Vehicle A) Energy rating [ER] Distance rating [DR] rough smooth smooth rough depends on number of opportunity to acceleration Energy economy rating [EER] Absolute speed change rating [ASCR] obvious difference rough smooth rough smooth

Test results (Vehicle A) Root mean squared speed error [RMSSE] Impact on fuel economy RMSSE becomes higher value when Smoothing/Rough driving worse better ER, DR, EER，ASCR and RMSSE became closer to zero when the vehicle follow the target speed (Normal driving). In case of a smoothing or rough driving, those index values became higher or lower value. This indicates that there is a possibility to detect the inappropriate driving.

Driving indexes and fuel economy impact (vehicle A) ●LOW hot ▲MID hot ■HIGH hot ◆ExHIGH hot ●LMH hot ▲LMHxH hot ○LOW cold △MID cold □HIGH cold ◇ExHIGH cold ●LMH cold ▲LMHxH cold Energy rating [ER] Distance rating [DR] Energy economy rating [EER] Possible criteria Possible criteria worse better worse better worse better linear relationship linear relationship Absolute speed change rating [ASCR] Root mean squared speed error [RMSSE] Possible criteria Possible criteria worse better worse better

Summary (Vehicle A) ER DR Smooth driving: Negative value Rough driving: Positive value Index value varies depend on each phase DR Smooth driving: Positive value Rough driving: Negative value Difficult to detect inappropriate driving technique EER Almost same characteristics as ER a significant difference according to driving techniques linear relationship to fuel economy impact (only smooth driving) ASCR RMSSE

Consideration of special treatment during wide-open-throttle During acceleration events, vehicle B could NOT follow the target speed with wide open throttle (WOT) operation. Need to consider how to treat in case of WOT operation. Special treatment: treat as same speed as target speed during WOT operation. (index value will be over-evaluated when excluding all WOT portions from calculation) unable to follow despite of WOT operation

Test results（Vehicle B） Energy rating [ER] Energy rating [ER] with special treatment Distance rating [DR] Distance rating [DR] with special treatment

Test results （Vehicle B） Energy economy rating [EER] [EER] with special treatment decrease Absolute speed change rating [ASCR] ASCR with special treatment not change so much

Test results (Vehicle B） Root mean squared speed error [RMSSE] RMSSE with special treatment Special treatment is necessary Impact on fuel economy worse better

Driving indexes(with special treatment) and fuel economy impact (vehicle B) ●LOW hot ▲MID hot ■HIGH hot ◆ExHIGH hot ●LMH hot ▲LMHxH hot ○LOW cold △MID cold □HIGH cold ◇ExHIGH cold ●LMH cold ▲LMHxH cold Energy rating [ER] with special treatment Distance rating [DR] with special treatment Energy economy rating [EER] with special treatment worse better worse better worse better linear relationship Absolute speed change rating [ASCR] with special treatment Root mean squared speed error [RMSSE] with special treatment Possible criteria Possible criteria worse better worse better

Driving indexes(without special treatment) and fuel economy impact (vehicle B) ●LOW hot ▲MID hot ■HIGH hot ◆ExHIGH hot ●LMH hot ▲LMHxH hot ○LOW cold △MID cold □HIGH cold ◇ExHIGH cold ●LMH cold ▲LMHxH cold Energy rating [ER] Distance rating [DR] Energy economy rating [EER] worse better worse better worse better Absolute speed change rating [ASCR] Root mean squared speed error [RMSSE] worse better worse better Need special treatment

Summary (Vehicle B) ER, DR, EER with special treatment ER, DR, EER could not detect inappropriate driving technique, due to offset positive and negative side. ASCR ASCR won’t change much when special treatment was applied. ASCR is able to detect the smooth and/or rough driving. RMSSE RMSSE need special treatment to detect the smooth and/or rough driving. with special treatment

Test results (Vehicle C） During gear shift events, no tolerance is required. Treat as same speed as target speed during gear shift events±1sec. gearshifting±1sec

Test results (Vehicle C） Energy rating [ER] Energy rating [ER] with special treatment become worse!! Distance rating [DR] Distance rating [DR] with special treatment

Test results (Vehicle C） Energy economy rating [EER] [EER] with special treatment become worse!! Absolute speed change rating [ASCR] ASCR with special treatment become worse!!

Test results (Vehicle C） Root mean squared speed error [RMSSE] RMSSE with special treatment 変化小さい Impact on fuel consumption To treat as same speed as target speed during gear shift events is not effective. More study for gear shift events is necessary. worse better

Driving indexes(with special treatment) and fuel economy impact (vehicle C) ●LOW hot ▲MID hot ■HIGH hot ◆ExHIGH hot ●LMH hot ▲LMHxH hot ○LOW cold △MID cold □HIGH cold ◇ExHIGH cold ●LMH cold ▲LMHxH cold Energy rating [ER] with special treatment Distance rating [DR] with special treatment Energy economy rating [EER] with special treatment worse better worse better worse better Absolute speed change rating [ASCR] with special treatment Root mean squared speed error [RMSSE] with special treatment worse better worse better

Driving indexes(without special treatment) and fuel economy impact (vehicle C) ●LOW hot ▲MID hot ■HIGH hot ◆ExHIGH hot ●LMH hot ▲LMHxH hot ○LOW cold △MID cold □HIGH cold ◇ExHIGH cold ●LMH cold ▲LMHxH cold Energy rating [ER] Distance rating [DR] Energy economy rating [EER] worse better worse better worse better Absolute speed change rating [ASCR] Root mean squared speed error [RMSSE] Possible criteria worse better worse better Possible criteria

Summary (Vehicle C) with special treatment It was observed that the treatment (same as target speed) doesn’t work for gear shift events. More effective treatment during gear shift events is necessary to adopt driving index requirement. with special treatment