Before applying for a new Type Approval, or extension of an existing certificate, the applicable tests must be agreed with the Technical Service. A later blog in this series will cover the subject of approval extensions, so for this post we will consider new approvals.
Where a manufacturer has multiple variants and/or configurations, worst-casing can significantly reduce the amount of testing required to demonstrate conformity with the technical requirements of R10.05. The latest revision of the 1958 Agreement requires the worst-case to be fully documented and included with the approval.
In order to make decisions on which variants/configurations to test, the Technical Service needs to have a good understanding of what the differences are between the variants/configurations and, in the case of vehicles, what systems are to be approved with the vehicle. The information document (Annex 2A/B) should contain a lot of this information, however the Technical Service will normally have additional questions to adequately justify the Worst-Case decisions taken. A manufacturer may know exactly what a B71X-VEU-12887 is, but without any explanatory information the Technical Service will have nothing on which to base a decision, and often will default to an “if in doubt, test it” position.
TEST EXCEPTIONS
Broadband radiated emissions testing is always required, however R10.05 has a number of test exceptions listed in Section 6.10.
If there are no electronic oscillators within the vehicle or ESA operating at a frequency above 9 kHz, then there is little chance of narrowband radiated emissions occurring and so the Type is deemed to meet the requirements of the regulation and applicable Annex (Annex 5 in the case of a vehicle and Annex 8 in the case of an ESA) without the need for a test.
If the vehicle or ESA does not have any “immunity related functions” then it is deemed to meet the requirements of the regulation and applicable Annex (Annex 6 in the case of vehicles, Annex 9 in the case of ESAs) without the need for testing. The next section of this blog explains the concept of “immunity related functions”.
In the case of ESAs, if the Type is not switched, contains no [electro-mechanical] switches e.g. relays, or has no inductive loads then there is no potential source of transient emissions on the power supply lines and so it is deemed to meet the requirements of the regulation.
Although it is not explicitly stated in R10.05, where an exception has been applied, it should be documented either in the Test Report or the worst-case document.
Section 6.10 of R10.05 also contains exceptions for electrostatic discharge testing and for RF receiver and transmitter performance within bands based around the bandwidth requirements thereof. Where a vehicle or ESA incorporates a transmitter, then it must be in transmit mode during testing. This can be challenging to achieve within a screened test chamber and may require the use of a network simulator, or similar, in order to prevent the transmitter timing-out or going into a standby or sleep mode during the test. Care is needed during immunity testing if using a live network link, especially when using a repeater. It is possible to cause network disruption (which the operators really take exception to), unintentionally transmit RF energy on restricted bands, interfere with commercial broadcasting or block essential signals such as aeronautical navigation beacons and bands used by emergency services. In the case of the latter this could lead to prosecution by the spectrum management agency for the country concerned. The laboratory performing the tests should be aware of these issues and take the necessary precautions.
IMMUNITY RELATED FUNCTIONS
R10.05 is primarily a safety based regulation, as opposed to being performance based, and is concerned with minimizing interference with vehicle systems and protecting the driver, passengers and other road users. “Immunity related functions” are defined in Section 2.12 of the regulation and some examples are provided.
Despite a fairly comprehensive definition, there are occasions when a difference of opinion arises on whether a particular ESA has immunity related functions. In such instances, the Approval Authority may make an interpretation. Approval Authorities meet on a regular basis to share experience and to discuss such matters so that [theoretically] there is a common approach.
OPERATING MODES
ESAs that have more than one operating mode may need to be tested multiple times to ensure the maximum radiated emissions are captured. Or, in the case of immunity, that the ESA operates correctly in the presence of an electromagnetic field in each mode. At vehicle level it may also be necessary to perform tests multiple times to cover the various operating modes.
The Technical Service may be able to technically justify only a single mode of operation, or in the case of vehicles, may cover the different operating modes by specifying a different mode for each vehicle tested.
To illustrate this concept, consider the case of adaptive headlights. In normal operation they may be in ‘High Beam’ mode, but switch to a ‘Dipped Beam’ mode when the ambient light is above a set threshold or an approaching vehicle is detected (the system may well be more complex than this simple example!). ‘High Beam’ mode is a potential distraction to other road users and so the ESA has an “immunity related function”. The Technical Service then needs to ensure that the ESA does not switch mode in response to an RF stimulus; switching to ‘High Beam’ in daylight with oncoming vehicles, or switching to ‘Dipped Beam’ in the dark with an empty carriageway. The Technical Service may decide that two tests are necessary, or a single test may be sufficient depending on the implementation.
WORST-CASE SELECTION
In the case of vehicles, it may be necessary to test multiple vehicles to ensure that all electrical systems that can be installed on the vehicle are covered by the base approval. For example, where there are different electrical transmission options, then vehicles with each type installed must be tested in accordance with the applicable Annexes. If however, the individual transmissions have been Type Approved separately as ESAs then there is no need for the base-approval to cover the transmissions.
It may also be the case that not all options are available on all models and so it is not possible to test for every system on a single vehicle.
The engine control unit (ECU), or engine control module (ECM), was introduced in the 1970s. Since then, ECUs have been developed to control almost all aspects of a vehicle and even a basic model contains around 50 modules. Luxury models can contain well over 150 modules, and as additional features such as driver assist and autonomous driving proliferate this number will only increase making the task of worst-casing ever more complex.
Individual ESAs are less complex, but can still have multiple variants. The Technical Service will try to minimize the number of tests required wherever possible. For radiated emissions, they may decide that only the variant that draws the most current from the vehicle battery needs to be tested, or it may be the technically most complex variant that is more appropriate.
If the ESA has different communication bus options (CAN, LIN, FlexRay etc.) then it may be necessary to test each option to capture the worst-case emissions and ensure data bus functionality during immunity testing. If the ESA is not connected to a data bus that has other ESAs with “immunity related functions” connected to it, then only one option may be sufficient.
From the above it should be clear that Worst-Casing can be technically challenging, and requires the participation of both the manufacturer and the Technical Service.
For the next blog in this series we will move on to the EMC tests themselves, beginning with radiated emissions and immunity testing of vehicles.
REFERENCES
UNECE Regulation 10, Revision 5 (9 October 2014): https://www.unece.org/fileadmin/DAM/trans/main/wp29/wp29regs/2015/R010r5e.pdf
UNECE Regulation 10, Revision 5, Amendment 1 (8 October 2016): https://www.unece.org/fileadmin/DAM/trans/main/wp29/wp29regs/2016/R010r5am1e.pdf
E/ECE/TRANS/505/Rev.3 (The 1958 Agreement, Revision 3 (14 September 2017))
https://www.unece.org/fileadmin/DAM/trans/main/wp29/wp29regs/2017/E-ECE-TRANS-505-Rev.3e.pdf
