Determination of System Equivalency – TaskForce Audi, EA-52, V4.0 WLTP-10-33e

2 Background ► In GTR 15 an annex is reserved for determination of system equivalency. Objective is to provide a procedure for comparison and validation of alternative measurement equipment and measurement procedures. ► Similar regulation is found in GTR 4 (WHDC Heavy Duty Testing Procedure) and recently in EPA Regulations 40 CFR (c)(7) and 40 CFR 1066 ► Both procedures are based on a statistical approach in which the candidate system and a reference system are compared. A couple of measurement pairs have to meet specific statistical criteria to show equivalence. Audi, EA-52, March 2015

3 Summary and Recommendation Summary: ► Determination of system equivalence is necessary to adapt the regulation to technical progress regarding alternative measurement equipment and measurement procedure. ► Current GTR 4 and EPA 1066 regulation provide a decision procedure based on a statistical approach. ► GTR 4 uses a definite criterion for decision on equivalency of different systems. EPA follows a more generic approach allowing new described procedures, but with the validation of results in the in use verification programs afterwards. Conclusion of meeting WLTP #8: ► Provision of Determination of system equivalence will be further discussed and developed. ► A taskforce meeting was held on with participation of experts of measurement equipment and measurement procedures in order to review and to amend the existing provisions. EPA sent written feedback and supports approach of gtr 4. ► Proposal is included to be presented in WLTP IWG meeting #10. Audi, EA-52, March 2015

4 Positions and Results of Task Force Audi, EA-52, March 2015

5 Definitions ► Accuracy of a measurement system is the degree of closeness of measurements of a quantity to that quantity's actual (true) value. [1] The precision of a measurement system, related to reproducibility and repeatability, is the degree to which repeated measurements under unchanged conditions show the same results. [1] [ Audi, EA-52, March 2015 [1] Bland, J.M.; Altman, D.G. (1996). "Statistics notes: measurement error.". Bmj, 312(7047), Retrieved 22 November 2013."Statistics notes: measurement error." Accuracy according to ISO 5725 Low accuracy, poor precision, Low accuracy, good precision, good trueness poor trueness

6 Standard Deviation ► Standard deviation (σ) measures the amount of variation or dispersion from the average. [1] A low standard deviation indicates that the data points tend to be very close to the mean (also called expected value); a high standard deviation indicates that the data points are spread out over a large range of values. [1] Audi, EA-52, March 2015 [1]Bland, J.M.; Altman, D.G. (1996). "Statistics notes: measurement error.". Bmj, 312(7047), Retrieved 22 November 2013."Statistics notes: measurement error."

7 Proposal for Inclusion in GTR 15 (I) Upon request of the manufacturer other systems or procedures may be approved by the type approval authority, if it is found that they yield equivalent results in accordance with paragraph xxx. The equivalence of the candidate system or procedure shall be demonstrated to and accepted by the authority. Paragraph xxx ► A candidate measurement equipment or procedure shall be considered equivalent, if the accuracy is same or better than the reference system or procedure and if additionally the reproducibility and repeatability is same or better than the reference system or procedure. Audi, EA-52, March 2015

8 Proposal for Inclusion in GTR 15 (II) ► Determination of Equivalency The determination of system equivalency shall be based on a correlation study between the candidate system and the reference systems. ► "Results" refer to the specific cycle weighted emissions value. The correlation testing is to be performed at the same location, test cell if appropriate, and on the same engine or vehicle and is preferred to be run concurrently. The equivalency of the sample pair averages shall be determined by statistics as described in Paragraph yyy obtained under the laboratory test cell and the engine conditions described above. Outliers shall be determined in accordance with ISO 5725 and excluded from the database. ► The systems to be used for correlation testing shall be subject to the approval by the type approval or certification authority. Audi, EA-52, March 2015

9 Proposal (III) Audi, EA-52, March 2015

10 Proposal (IV) Audi, EA-52, March 2015

11 Proposal (V) Audi, EA-52, March 2015