1. WLTP-25-07e
Gearshift Issues
Heinz Steven 1

2. Current status
At IWG #24 in Tokyo, proposals of text changes resulting from the analysis of the results of the 2nd round-robin test were presented and discussed.
These proposals were intended to clarify the interpretation of the text of annex 2. They were adopted by the IWG and included in amendment 5 of GTR 15.
With these amendments the gearshift issues task force (GSTF) was closed.
During further checks of the ACCESS calculation tool after IWG #24 the TF leader found an inconsistancy related to paragraph 4(a) of annex 2. 2

3. Further text amendment
The 2nd sub-paragraph of paragraph 4(a) reads as follows:
Gears used during accelerations at vehicle speeds ≥ 1 km/h shall be used for a period of at least 2 seconds.
It is proposed to apply this 2 second rule not only to acceleration phases but also to constant speed sections in order to avoid inconsistencies:
Gears used during accelerations or constant speed sections at vehicle speeds ≥ 1 km/h shall be used for a period of at least 2 seconds.  Proposal from H. Steven.4
This proposal is already implemented in the latest ACCESS calculation tool dated , which was distributed together with the proposal at 3

4. Proposal for adding a program code to annex 2 of GTR 15
One member of the GSTF contacted the TF leader and requested to add a programmatic description for the annex 2 calculations to annex 2.
At the preparatory web-telco for IWG #25 was decided that this request should be discussed.
The GSTF member sent the following text for the motivation and a proposal to the TF leader: 4

5. Motivation
The gear selection and shift point determination for vehicles equipped with manual transmissions as described in Annex 2 of GTR 15 is complex, especially when it comes to paragraph 4 “ Additional requirements for corrections and/or modifications of gear use”.
The 1st RRT showed that none of the tested calculation tools were completely in line with the current Annex 2 requirements and that Annex 2 needed to be further amended in order to close gaps and to better define the requirements as intended by the GSTF.
Despites the numerous amendments made to improve Annex 2 wording, the 2nd RRT showed again that none of the tested calculation tools were completely in line with the current Annex 2 requirements leading to some additional amendments of Annex 2 text.
Keeping a strict textual approach for gear selection and shift point determination for vehicles equipped with manual transmissions will always leave room for different interpretations leading to possible different and wrong implementations in the calculation tools. 5

6. Proposal
A programmatic description of the gear selection and shift point determination for vehicles equipped with manual transmissions would avoid any possible different interpretations.
Therefore, the proposal is to add as an Appendix of GTR 15 Annex 2, a programmatic description in one of the existing/modern reference programming languages e.g. C#, Python or Visual Basic (to be decided).
This programmatic description must be well structured and provide clear references to GTR 15 Annex 2 paragraphs. This will provide a strong reference basis that can be used for implementation inside various calculation tools (potentially using different programming languages) and would also help for the validation of those implementations.
This approach is already adopted in some SAE standards (see next slide for an example). 6

7. Example
The SAE paper J2951, i.e. Drive Quality Evaluation for Chassis Dynamometer Testing, in its Appendix D provides a Matlab based code intended to demonstrate the mathematical implementation. 7

8. Thank you for your attention!
End
Thank you for your attention! 8